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A Multicenter Phase I/II Study of Obatoclax Mesylate Administered as a 3- or 24-Hour Infusion in Older Patients with Previously Untreated Acute Myeloid Leukemia

A Multicenter Phase I/II Study of Obatoclax Mesylate Administered as a 3- or 24-Hour Infusion in... Purpose: An open-label phase I/II study of single-agent obatoclax determined a maximum tolerated dose (MTD) and schedule, safety, and efficacy in older patients ($70 yr) with untreated acute myeloid leukemia (AML). Experimental Design: Phase I evaluated the safety of obatoclax infused for 3 hours on 3 consecutive days (3 h63d) in 2- week cycles. Initial obatoclax dose was 30 mg/day (3 h63 d; n = 3). Obatoclax was increased to 45 mg/day (3 h63d) if #1 patient had a dose-limiting toxicity (DLT) and decreased to 20 mg/day (3 h63 d) if DLT occurred in $2 patients. In the phase II study, 12 patients were randomized to receive obatoclax at the dose identified during phase I (3 h63 d) or 60 mg/ day administered by continuous infusion over 24 hours for 3 days (24 h63 d) to determine the morphologic complete response rate. Results: In phase I, two of three patients receiving obatoclax 30 mg/day (3 h63 d) experienced grade 3 neurologic DLTs (confusion, ataxia, and somnolence). Obatoclax was decreased to 20 mg/day (3 h63 d). In phase II, no clinically relevant safety differences were observed between the 20 mg/day (3 h63 d; n = 7) and 60 mg/day (24 h63 d; n = 5) arms. Neurologic and psychiatric adverse events were most common and were generally transient and reversible. Complete response was not achieved in any patient. Conclusions: Obatoclax 20 mg/day was the MTD (3 h63 d) in older patients with AML. In the schedules tested, single-agent obatoclax was not associated with an objective response. Evaluation in additional subgroups or in combination with other chemotherapy modalities may be considered for future study. Trial Registration: ClinicalTrials.gov NCT00684918 Citation: Schimmer AD, Raza A, Carter TH, Claxton D, Erba H, et al. (2014) A Multicenter Phase I/II Study of Obatoclax Mesylate Administered as a 3- or 24-Hour Infusion in Older Patients with Previously Untreated Acute Myeloid Leukemia. PLoS ONE 9(10): e108694. doi:10.1371/journal.pone.0108694 Editor: Maria R. Baer, University of Maryland, United States of America Received May 16, 2014; Accepted August 19, 2014; Published October 6, 2014 Copyright:  2014 Schimmer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All data are included within the paper. Funding: The study that is the subject of this manuscript was sponsored by Gemin X Pharmaceuticals, Inc., which was acquired by Cephalon, Inc., a wholly- owned subsidiary of Teva Pharmaceutical Industries, Ltd (TEVA). The development and publication of this manuscript has been financially supported by TEVA. Employees of TEVA were actively involved in the development of the manuscript, including providing data as well as review and comment of manuscript drafts. Powered 4 Significance LLC was contracted by TEVA to provide medical writing assistance in preparing an initial draft of the manuscript and editorial assistance. Competing Interests: The authors have read the journal’s policy and have the following competing interests: ADS, GB, and THC report research support from GeminX, during the conduct of the study; HE reports compensation from Celgene, Novartis, Celator, Sunesis, Seattle Genetics, and Incyte, outside the submitted work; AR, DC, DJD, CG, and MST have no competing interests to declare. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials. * Email: aaron.schimmer@utoronto.ca States, a total of 14,590 new AML diagnoses were projected to Introduction occur in 2013, with an estimated 10,370 deaths [2]. AML is Acute myeloid leukemia (AML) is a heterogeneous hematologic predominantly a disease of older adults with a median age at malignancy that results from the clonal expansion of primitive diagnosis of 66 years [3]. Compared with younger patients (,55 myeloid precursor cells [1]. AML is the most common form of years), AML in older patients ($55 years) is more frequently acute leukemia in adults, and has a high mortality. In the United PLOS ONE | www.plosone.org 1 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Figure 1. Study design. CR, complete response; DLT, dose-limiting toxicity. doi:10.1371/journal.pone.0108694.g001 associated with a poor prognosis, in part due to decreased response suggested that a subset of treatment-naive patients with AML might benefit from obatoclax therapy. rates and increased toxicity of standard induction chemotherapy. Consequently, there is an unmet need for therapies that provide Continuous infusion of obatoclax 60 mg/day for 3 days (24 h63 d) in 2-week cycles has previously been evaluated in efficacy and favorable tolerability in older patients with AML. phase II trials in patients with myelofibrosis or Hodgkin’s Development of small-molecule inhibitors specific for anti- lymphoma [13,15]. An accelerated 3-hour infusion, 3-day apoptotic proteins is a novel approach to the treatment of (3 h63 d) regimen has not yet been evaluated in a 2-week cycle hematologic cancers. Anti-apoptotic B cell-chronic lymphocytic in patients with hematologic malignancies, nor have these leukemia/lymphoma 2 (Bcl-2) family members (Bcl-2, Bcl-XL, regimens been formally compared. The objectives of this Bcl-w, Bcl-b, A1/Bfl-1, and Mcl-1) are overexpressed in many multicenter phase I/II study were to expand on previous cancers and inhibit apoptosis by sequestering pro-apoptotic experiences with obatoclax and to evaluate the dose and schedule members of the family (BH3-only proteins, and Bax and Bak) of single-agent obatoclax for safety and efficacy in older patients [4,5]. Importantly, emerging evidence suggests that anti-apoptotic with previously untreated AML. Mcl-1 is critical for sustained survival and expansion of human AML and plays a role in drug resistance in this disease [6]. Since Patients and Methods interactions between anti- and pro-apoptotic family members are mediated by the BH3 domain protein interaction motif [4,5], Study Design small molecules that bind to the BH3 binding groove may induce An open-label, multicenter, phase I/II study was conducted. apoptosis by inhibiting sequestration of pro-apoptotic factors [7]. The protocol for this trial and supporting CONSORT checklist Obatoclax mesylate (obatoclax, also known as GX15-070) is a are available as supporting information; see Checklist S1 and novel anticancer therapeutic for hematologic malignancies and Protocol S1. The phase I portion of the study consisted of a solid tumors. The compound, which acts as a BH3 mimetic, was nonrandomized safety evaluation, followed by a randomized phase developed as a pan-inhibitor of anti-apoptotic members of the Bcl- II evaluation of different treatment schedules (Figure 1). The 2 family, including Mcl-1, to trigger cell death [8,9]. Preclinical phase I safety evaluation assessed obatoclax as a 3-hour infusion investigations demonstrated that obatoclax induces apoptosis and over 3 consecutive days (3 h63 d). Because the optimal schedule reduces proliferation in AML cell lines and primary AML cells, in for obatoclax treatment was unknown, the phase II evaluation part by inhibition of Mcl-1 sequestration of Bax [10]. utilized a randomized open-label design to assess 3-hour or 24- In phase I trials of single-agent obatoclax, antitumor activity was hour infusion schedules, over 3 consecutive days (3 h63d or observed in several hematologic malignancies, including AML, 24 h63 d). The selected dose for the 24-hour infusion was the myelodysplastic syndrome, and Hodgkin’s and non-Hodgkin’s previously defined maximum tolerated dose (MTD) of 60 mg/day lymphoma [11–14]. Although there were a limited number of [16]. objective responses in these early clinical studies, hematologic improvement was observed in a larger proportion of treated Ethics Statement patients. One striking clinical response occurred in a 70-year-old The study was conducted in accordance with the October 2000 woman with previously untreated AML who achieved a complete version of the Declaration of Helsinki, as well as Good Clinical response (CR) after receiving 20 mg/m obatoclax as a 24-hour Practice and International Conference on Harmonisation guide- infusion [14]. Her CR was maintained over 8 months and lines. An accredited institutional review board approved this study PLOS ONE | www.plosone.org 2 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML prior to its initiation and all patients provided informed written antibiotics, IV immunoglobulins, and hematopoietic growth consent. This study was registered at clinicaltrials.gov factors. (NCT00684918). Endpoints and Assessments Patient Eligibility Endpoints. Safety endpoints included number of DLTs, Patients at least 70 years of age with histologically confirmed treatment-emergent AEs, including serious AEs, and clinical AML were eligible to participate. In the phase I portion of the laboratory values. AEs were recorded according to the National study, patients may have received one previous therapy. In the Cancer Institute Common Terminology Criteria for Adverse phase II portion of the study, no prior therapy for AML was Events, version 3.0 [17]. allowed except for hydroxyurea. Additional eligibility require- Clinical response was assessed using standard criteria [18]. The ments included Eastern Cooperative Oncology Group (ECOG) primary efficacy endpoint was rate of morphologic CR, or performance status #2 and normal hepatic and renal function cytogenetic CR in patients with abnormal cytogenetics at baseline. (total bilirubin #2 mg/dL unless resulting from hemolysis; Morphologic CR was defined as neutrophils .1000/mL, platelets aspartate transaminase/alanine transaminase #2.56 institutional .100,000/mL, and bone marrow blasts ,5%. Cytogenetic CR upper limit of normal; creatinine within normal institutional limits was defined as neutrophils .1000/mL, platelets .100,000/mL, or creatinine clearance $50 mL/min/1.73 m for patients with bone marrow blasts ,5%, and normal cytogenetics. Additional creatinine levels above institutional normal). efficacy endpoints included molecular CR, partial remission (PR), Patients were excluded if they had a history of allergy to and morphologic leukemia-free state, and change in bone marrow components of the formulated product. Comorbidities requiring blasts from baseline to post-induction therapy (day 28). patient exclusion included a history of seizure disorder or central Schedule of assessments. AEs were recorded from baseline nervous system leukemia or other symptomatic neurologic illness; screening to 28 days after the last obatoclax dose. Complete blood uncontrolled systemic infection considered opportunistic, life- counts (absolute neutrophil count, lymphocytes, monocytes, threatening, or clinically significant; symptomatic congestive heart eosinophils, and basophils) were obtained on day 1 of each cycle, failure; unstable angina pectoris; cardiac arrhythmia; significant every 2–3 days for the first week of cycle 1, and on day 8 of each pulmonary disease or hypoxia; psychiatric illness/social situation cycle. Physical and neurologic examinations, including vital signs, that would limit compliance with study requirements; or infection body weight, ECOG performance status, and serum chemistries with human immunodeficiency virus. were performed at baseline and on days 1 and 8 of each cycle. Chest radiographs, pulmonary function tests, and urinalysis were conducted at baseline and at the 28-day follow-up visit. An Treatments electrocardiogram was obtained at baseline, 30 minutes before the Obatoclax mesylate (30 mg) was diluted with 5% dextrose, USP end of infusion on day 3 in cycle 1, and at the 28-day follow-up and a final concentration of 11.54% polyethylene glycol 300, visit, and repeated as clinically indicated. 0.46% polysorbate 20 for intravenous (IV) infusion. Treatments Bone marrow aspirates and biopsies were conducted at baseline, were evaluated as depicted in Figure 1. In the phase I portion of on day 28, after obatoclax consolidation therapy, and as clinically the study, the first 3 patients enrolled received obatoclax 30 mg/ indicated. CR was documented by repeat bone marrow exami- day over 3 hours for 3 consecutive days (3 h63 d). Dose-limiting nation on day 28 or earlier. Bone marrow cytogenetics were toxicities (DLTs) were defined as grade $3 infusion-related assessed at baseline, repeated on occurrence of CR, and as neurologic adverse events (AEs) and nonhematologic AEs not clinically indicated. responsive to symptom-directed therapy. If (during cycle 1) #1of the 3 patients experienced a DLT, subsequent enrolled patients would receive 45 mg/day for 3 consecutive days (3 h63 d). If, Statistical Analysis however, $2 of 3 patients experienced a DLT, an additional Safety was assessed in all patients who received any amount of group of 3 patients would be enrolled and would receive 20 mg/ study drug per National Cancer Institute Common Terminology day over 3 hours for 3 consecutive days (3 h63 d). If #1of3 Criteria for Adverse Events, version 3. Efficacy was assessed in all patients experienced a DLT at 20 mg/day, this dose would be patients with at least one post-baseline efficacy assessment. All utilized for the 3 h63 d phase II study. If $2 of the 3 patients outcomes were summarized descriptively. For categorical vari- experienced a DLT at 20 mg/day, the 3 h63 d schedule would be ables, summary tabulations of the number and percentage in each halted, and the phase II study would use only the 24 h63d parameter were provided. For continuous variables, the mean, schedule for obatoclax administration, which has previously been median, standard deviation, minimum, and maximum were shown to be well tolerated and produced a CR in a patient with presented. To determine the rate of morphologic CR, a two-stage AML [14]. design was used, powered to detect a CR rate of $15% against a In the phase II portion of the study, patients were randomized non-interesting rate of 5%, with alpha = 0.05 and a power of (1:1) into two arms. One arm received obatoclax at the dose 90%. Stage 1 was to enroll 37 patients under this design, and if $3 identified from phase I at 3 h63 d; the other arm received 60 mg/ patients achieved CR at the end of Stage 1, an additional 47 day (24 h63 d). In both phases, obatoclax was administered in patients would be enrolled. two 2-week cycles as induction therapy. Any patient achieving a CR could receive four additional treatment cycles as consolidation Results therapy every 2 weeks for a total of six cycles of obatoclax treatment. Patients who did not achieve CR after two cycles of Demographics and Patient Disposition obatoclax were to be removed from study. A total of 19 patients were enrolled in the study from March Prophylaxis with H-1 and H-2 blockers was recommended prior 2008 to March 2009; one patient did not receive obatoclax to each cycle, given the known prevalence of acute hypersensitivity treatment. Demographics and disease characteristics were similar reactions associated with obatoclax exposure [14]. Full supportive across all regimens (Table 1). Overall, the mean age was 81 years care was offered to treat acute nausea, vomiting, or DLTs as (range 72–90 years). The median time from AML diagnosis to appropriate, including anti-emetic prophylaxis, blood products, study entry was 0.6 months (range 0–37 months). Most (56%) PLOS ONE | www.plosone.org 3 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Table 1. Demographics and baseline characteristics of obatoclax-treated patients (N = 18). Phase I Phase II All (N = 18) 30 mg/d (3 h63d) 20 mg/d (3 h63d) 20 mg/d (3 h63d) 60 mg/d (24 h63d) (n = 3) (n = 3) (n = 7) (n = 5) Median (range) age, years 83 (81–85) 74 (72–90) 82 (72–89) 80 (76–86) 81.5 (72–90) Male, n (%) 1 (33) 1 (33) 3 (43) 3 (60) 8 (44) ECOG PS, n (%) 0 1 (33) 0 3 (43) 1 (20) 5 (28) 1 1 (33) 1 (33) 4 (57) 2 (40) 8 (44) 2 1 (33) 2 (67) 0 2 (40) 5 (28) Median time since AML diagnosis, 1 (0.5–7.4) 1.2 (1–16.7) 0.45 (20.2–0.6) 0.2 (0–37.2) 0.6 (20.2–37.2) months (range) AML classification, n (%) M1 1 (33) 0 3 (43) 0 4 (22) M2 2 (67) 1 (33) 3 (43) 4 (80) 10 (56) M3 0 1 (33)* 0 0 1 (6) M4 0 1 (33) 0 1 (20) 2 (11) Missing 0 0 1 (14) 0 1 (6) Cytogenetics, n (%) Abnormal 1 (33) 3 (100) 3 (43) 3 (60) 10 (56) Normal 1 (33) 0 2 (29) 2 (40) 5 (28) Missing 1 (33) 0 2 (29) 0 3 (17) Median leukocyte count (range), 10 /mL 1.3 (0.5–1.4) 29.2 (19.3–64.3) 4.3 (1.1–7.3) 2.8 (1.1–27.2) 4.25 (0.5–64.3) Median platelet count (range), 10 /mL 23 (8–154) 126 (69–227) 63 (19–518) 63 (19–259) 66 (8–518) Median hemoglobin (range), g/L 86 (86–102) 105 (99–110) 101 (86–117) 93 (90–100) 97.5 (86–117) 3 a b c d e Median neutrophil count (range), 10 /mL 0.2 (0.2–0.2) 1.95 (0.6–3.3) 0.39 (0.1–2.6) 6.98 (0.5–13.5) 0.55 (0.1–13.5) *Classified as acute promyelocytic leukemia. Evaluated in 1 patient. Evaluated in 2 patients. Evaluated in 5 patients. Evaluated in 2 patients. Evaluated in 10 patients. AML, acute myeloid leukemia; ECOG PS, Eastern Cooperative Oncology Group performance status. doi:10.1371/journal.pone.0108694.t001 patients had a French-American-British classification of M2; the Safety distribution of AML classification was similar for all regimens. In the phase I safety study, two of three patients treated with Approximately 56% of patients had an abnormal karyotype; 30 mg/day (3 h63 d) experienced grade 3 neurologic events that further details of the cytogenetic abnormalities were not available, led to discontinuation of treatment and were classified as DLTs thus precluding classification of cytogenetics into risk groups. (Table 3). The first patient experienced grade 3 somnolence (day Patient disposition is shown in Figure 2. The most common 1) and grade 3 confusion. This patient also experienced dizziness, reasons for withdrawal from the study were failure to achieve CR mood alteration, and speech disorder during infusion (all grade , following induction therapy (eight patients, 42%), adverse events 3; Table 4). The second patient experienced grade 3 ataxia and (including DLT; four patients, 21%), and disease progression grade 1 confusion, euphoria, and somnolence on day 1 of cycle 1. (three patients, 16%). Two patients were granted waivers for In both patients, neurologic DLTs were assessed as definitely laboratory abnormalities (hyperuricemia) at baseline. related to study drug and resolved within 24 hours. The third The number of treatment cycles administered in the phase I/II patient in this group also experienced euphoria and ataxia (grade studies is shown in Table 2. Overall, the median number of ,3) and discontinued due to leukemic infiltrate. One serious AE cycles administered was two (range 1–11). In both the phase I and (grade 3 neutropenic fever) was reported for this regimen, but was II studies, a total of 15 patients (83%) were treated for at least two judged to be unrelated to study drug (Table 3). cycles. Four patients also received additional treatment cycles as Per protocol, the obatoclax dose in the 3 h63 d regimen was consolidation therapy as they experienced disease stabilization or decreased to 20 mg/day in a subsequent cohort of three patients. decreased blast counts in the marrow, although these continued No additional DLTs were observed in this group and only one cycles were considered protocol deviations. Of these four patients, grade 3 serious AE (pneumonia) was reported and was considered one patient received a total of eight cycles of therapy, two patients unrelated to study drug. In addition, one patient experienced received a total of four cycles, and one patient received a total of grade 2 cytokine release syndrome, which was also considered a serious AE (Table 3). Therefore, the 20 mg/day (3 h63d) 11 cycles. regimen was chosen for the randomized phase II portion of the PLOS ONE | www.plosone.org 4 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Figure 2. Patient disposition. AE, adverse event; CR, complete response. doi:10.1371/journal.pone.0108694.g002 study for comparison with obatoclax 60 mg/day (24 h63 d), as obatoclax. Acute myocardial infarction resulted in treatment previously defined in a small study of 18 patients [16]. discontinuation in one patient. In the phase II study, most patients receiving either obatoclax Combining both the phase I and II components of the study, all 20 mg/day (3 h63 d) or 60 mg/day (24 h63 d) experienced mild 18 (100%) patients who received obatoclax experienced at least 1 to moderate (grade ,3), transient, neurologic AEs such as AE, the most common of which were neurologic (n = 14; 77.8%) euphoria, somnolence, ataxia, dizziness, and confusion (Table 4). or psychiatric (n = 16; 88.9%); most were transient and mild, and AEs of grade $3 that were reported in more than one patient resolved without sequelae. Ten patients experienced serious AEs; included febrile neutropenia (n = 3), dizziness (n = 2), atrial details are provided in Table 3. Evidence for trends between fibrillation (n = 2), and acute myocardial infarction (n = 2). The severity of AEs (grade $3) and dose or schedule was not observed events of dizziness, atrial fibrillation, and acute myocardial (Table 4). AEs (any grade) with the highest reported incidence infarction were considered to be at least possibly related to included euphoria (67%), somnolence (44%), and ataxia (39%). Table 2. Study drug exposure in patients treated with obatoclax (N = 18). Phase I Phase II All (N = 18) 3-h infusion (20 mg/d) 24-h infusion (60 mg/d) 30 mg/d (n = 3) 20 mg/d (n = 3) (n = 7) (n = 5) Median number of cycles (range) 2 (1–2) 4 (4–8) 2 (2–11) 2 (1–2) 2 (1–11) Total cycles, n (%) 1 3 (100) 3 (100) 7 (100) 5 (100) 18 (100) 2 2 (67) 3 (100) 7 (100) 3 (60) 15 (83) 3 0 3 (100) 1 (14) 0 4 (22) 4 0 3 (100) 1 (14) 0 4 (22) 5 0 1 (33) 1 (14) 0 2 (11) 6 0 1 (33) 1 (14) 0 2 (11) 7 0 1 (33) 1 (14) 0 2 (11) 8 0 1 (33) 1 (14) 0 2 (11) .9 0 0 1 (14) 0 1 (6) doi:10.1371/journal.pone.0108694.t002 PLOS ONE | www.plosone.org 5 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Table 3. Summary of dose-limiting toxicities and serious adverse events. Phase I Phase II 3-h infusion (20 mg/d) 24-h infusion (60 mg/d) 30 mg/d (n = 3) 20 mg/d (n = 3) (n = 7) (n = 5) Dose-limiting toxicity Grade 3 somnolence/confusion 00 0 (1); grade 3 ataxia (1) Serious TEAE, n (grade, attribution) Febrile neutropenia 1 (gr 3, NR) 1 (gr 3, NR) Atrial fibrillation 2 (gr 3, NR; gr 3, NR) Acute myocardial infarction 1 (gr 3, NR) 1 (gr 4, PS) Cough 2 (gr 1, NR; gr 2, PS) Catheter site infection 1 (gr 3, NR) 1 (gr 3, NR) Cytokine release syndrome 1 (gr 2, PR) Pneumonia 1 (gr 3, NR) 1 (gr 3, NR) Acute sinusitis 1 (gr 1, NR) Dyspnea 1 (gr 2, NR) Fatigue 1 (gr 5, NR) Dizziness 1 (gr 3, PR) AE, adverse event; DLT, dose-limiting toxicity (DLTs were defined as grade $3 infusion-related neurologic AEs and nonhematologic AEs not responsive to symptom- directed therapy); PR, probably related; PS, possibly related; NR, not related; TEAE, treatment-emergent adverse event. doi:10.1371/journal.pone.0108694.t003 Somnolence was the most commonly reported grade $3AE weeks) by 3-hour or 24-hour infusion was generally mild and (17%). The most common grade $3 toxicities based on laboratory similar to previous reports [11–14]. AEs were typically transient, data were leukocytosis and thrombocytopenia (each n = 9). No neurologic, or psychiatric findings that resolved without sequelae. clinically meaningful differences were observed across regimens for Based on the safety profile, 20 mg/day was determined to be the laboratory reports of grade $3 hematologic findings. MTD of obatoclax when administered over 3 hours/day for 3 Two patients died during the study for reasons unrelated to consecutive days in older AML patients. Two patients treated with obatoclax administration. One patient on the 60 mg/day the 30 mg/day (3 h63 d) regimen experienced DLTs consisting of (24 h63 d) regimen died on day 23 of the study from progressive grade 3 confusion, somnolence, or ataxia, which led to premature disease. The second patient, receiving 20 mg/day (3 h63 d), died discontinuation and selection of the 20 mg/day dose for further on day 41; the cause of death is unknown. An additional six evaluation. In the phase II comparison of obatoclax 20 mg/day patients died more than 30 days after the last obatoclax dose. (3 h63 d) to the previously evaluated 60 mg/day (24 h63d) Causes of death in these patients were progressive disease (n = 2), regimen, both dosing schedules demonstrated similar safety sepsis (n = 1), and unknown (n = 3). profiles. The mechanism(s) underlying the development of neurologic or Efficacy psychiatric symptoms is uncertain. However, it is plausible that CR was not achieved with obatoclax induction. However, three these symptoms represent an on-target effect, since Bcl-2 promotes patients on the 20 mg/day (3 h63 d) regimen demonstrated a 7% neuron survival and Bcl-XL plays a role in synaptic plasticity to 17% decrease in bone marrow blast percentage between the [19,20]. Alternatively, the neurologic and psychiatric effects of baseline assessment and the end of cycle 2 (Table 5). It is obatoclax may reflect binding to targets other than Bcl-2 family noteworthy that two of these patients with decreased marrow members. blasts also demonstrated an increase of 33% to 57% in neutrophil Based on laboratory data, grade $3 leukocytosis and throm- count. Of these three patients, one patient in phase I receiving bocytopenia occurred in 50% of patients in this study. These obatoclax 20 mg/day (3 h63 d arm) had a decrease in marrow hematologic abnormalities are likely related to underlying disease blasts from 27% to 10% with increased neutrophils from rather than obatoclax as they were present at baseline. However, it 3 3 9344610 /mL to 14,700610 /mL. This patient received eight should be noted that inhibition of Bcl-XL by obatoclax may result cycles of study treatment and withdrew from the study on the in thrombocytopenia. Because patients also received platelet advice of the investigator. One additional patient in the phase II transfusions during the study as supportive care, the impact of portion of the study had increased neutrophil (pre-treatment: 3 3 obatoclax on platelet production may have been obscured. 230610 /mL; end of cycle 2: 2500610 /mL) and platelet counts 3 3 Six patients experienced cardiac events during this study, four of (pre-treatment: 73610 /mL; end of cycle 2: 250610 /mL) without which were assessed as at least possibly related to the study drug. a significant change in the marrow blasts. This patient remained The causal relationship with ischemic cardiac events, if any, is stable and received 11 cycles of obatoclax. unclear because patients in this study were older with multiple comorbidities. In other clinical studies evaluating obatoclax, QTc Discussion prolongation has been reported by automated electrocardiogram. The results of the current study demonstrate that the safety In a study of patients with relapsed small cell lung cancer, the profile of obatoclax administered for 3 consecutive days (every 2 interval between obatoclax doses was extended to 3 days in a PLOS ONE | www.plosone.org 6 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML PLOS ONE | www.plosone.org 7 October 2014 | Volume 9 | Issue 10 | e108694 Table 4. Treatment-emergent adverse events occurring in more than one patient. Phase II 3-h infusion (20 mg/d) Phase II 24-h infusion (60 mg/d) Phase I 20 mg/d (n = 3) Phase I 30 mg/d (n = 3) (n = 7) (n = 5) All (N = 18) n All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 Euphoria 3 0 2 0 6 1 1 0 12 1 Somnolence 0 0 2 2 4 1 2 0 8 3 Ataxia 0 0 3 1 3 0 1 1 7 2 Dizziness 1 0 1 0 2 1 1 1 5 2 Confusion 0 0 2 1 1 0 2 0 5 1 Constipation 1 0 1 3 5 Fever 0 0 0 0 3 1 2 0 5 1 Diarrhea 1 1 1 1 4 Peripheral edema 0 0 2 2 4 Febrile neutropenia 0 0 1 1 2 2 1 1 4 4 Disorientation 2 0 1 0 3 Cough 0 1 2 0 3 Unsteady gait 0 1 2 0 3 Insomnia 1 0 2 0 3 Dyspnea 0 0 1 2 3 Hypoxia 00 00 31 0 0 31 Dysarthria 1 0 2 0 3 Fatigue 0 0 0 0 2 0 1 1 3 1 Headache 0 0 2 1 3 Ecchymosis 0 0 3 0 3 Hypotension 0 0 1 1 2 Tachycardia 0 0 2 0 2 Cardiac murmur 0 0 2 0 2 Atrial fibrillation 0 0 0 0 2 2 0 0 2 2 Pneumonia 1 1 0 0 1 1 0 0 2 2 Loose stool 1 0 1 0 2 Gingival pain 0 1 1 0 2 Cytokine release syndrome 1 0 1 0 2 Abnormal breath sounds 0 0 1 1 2 AcuteMI 0 00 0 1 11 12 2 Dry mouth 0 0 1 1 2 Crackles (lung) 0 0 1 1 2 Thrush 0 0 2 0 2 Obatoclax in Older Patients with Untreated AML PLOS ONE | www.plosone.org 8 October 2014 | Volume 9 | Issue 10 | e108694 Table 4. Cont. Phase II 3-h infusion (20 mg/d) Phase II 24-h infusion (60 mg/d) Phase I 20 mg/d (n = 3) Phase I 30 mg/d (n = 3) (n = 7) (n = 5) All (N = 18) n All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 Hypocalcemia 0 1 1 0 2 Hypokalemia 0 1 1 0 2 Slurred speech 0 0 2 0 2 Agitation 0 0 0 0 1 1 1 0 2 1 Muscular weakness 0 0 1 1 2 Anxiety 0 1 1 0 2 doi:10.1371/journal.pone.0108694.t004 Table 5. Improvement in marrow blast count, neutrophil count, and platelet count in patients receiving obatoclax. 3 3 Blast count, % (aspirate) Neutrophils, 610 /mL Platelets, 610 /mL Patient Treatment (phase) AML Classification Base-line End Cycle 2 Baseline End Cycle 2 Baseline End Cycle 2 04.002* 20 mg/d (I) M4 27 10 9344 14,700 227 206 04.003 20 mg/d (I) M3 27 20 3300 4400 126 139 05.002 20 mg/d (II) M1 33 23 390 360 49 47 *Received eight cycles of obatoclax. AML, acute myeloid leukemia. doi:10.1371/journal.pone.0108694.t005 Obatoclax in Older Patients with Untreated AML single patient who experienced QTc prolongation during the first inducers of cell death. For example, obatoclax induced apoptosis cycle [14,21]. In another phase I dose escalation study in advanced in OCI-AML3 leukemic cells when used in combination with hematologic malignancies, grade 3 QTc prolongation was ABT-737 and synergistically induced apoptosis in combination observed in 3 patients, but was confounded by the presence of with cytosine arabinoside in leukemic cell lines and in primary QTc prolongation at baseline [14]. Notably, an imbalance in the AML samples [10]. Preclinical investigations also suggest that ratio of anti-apoptotic to pro-apoptotic Bcl-2 proteins appears obatoclax potentiates the effect of established drugs in AML [30– causal in the development of cardiovascular disease, including 32], and several clinical trials of obatoclax combined with ischemic heart disease [22], so relationship to study drug cannot be conventional chemotherapeutic agents have been completed or excluded. are ongoing in a range of solid tumors and hematologic In the current study, four patients had a clinical response of malignancies (e.g., NCT00612612, NCT00521144 at clinical- stable disease and were treated for up to 11 cycles. We did not trials.gov). observe a CR in this study. This contrasts with our previous report In conclusion, based on the safety profile described in this study, of a CR achieved with single-agent obatoclax (20 mg/m over 20 mg/day is the MTD of obatoclax when administered by 3-hour 24 hours) in one older treatment-naive patient with AML with a infusion over 3 consecutive days in an older AML population, and mixed-lineage leukemia (MLL) t(9;11) translocation [14]. Al- it has similar tolerability to a 60 mg/day (24 h63 d) regimen. though such dramatic single-agent activity in previously untreated Although the current study does not support the efficacy of AML was not confirmed by our data, it is possible that MLL- obatoclax as a single agent in an unselected group of treatment- associated leukemia may be particularly sensitive to Bcl-2 family naive AML patients, additional studies may reveal activity in select inhibitors. Preclinical studies have shown that inhibition of MLL subgroups, particularly in combination with other chemothera- expression using siRNA corresponded with reduced Bcl-XL levels peutics. and leukemic proliferation that may be mediated by HoxA9 [23,24]. Thus, Bcl-2 proteins may play an important role in the Supporting Information proliferation of MLL-associated leukemia. In addition, a limitation of our study is that pharmacodynamic activity or pharmacokinetic Protocol S1 Study protocol for open-label phase I/II parameters were not assessed. Integrating these evaluations in study of single-agent obatoclax in older patients ($70 yr) future clinical trials of obatoclax may provide further insight into with untreated acute myeloid leukemia (AML). the clinical potential of obatoclax as a single agent. (PDF) In addition to obatoclax, several other small-molecule BH3 Checklist S1 CONSORT checklist. mimetics are under investigation. ABT-737 and ABT-263 (DOC) (navitoclax), for example, bind three of six Bcl-2 family members with high affinity [25,26]. Navitoclax has been evaluated in phase Acknowledgments I trials in lymphoid malignancies [27,28]. However, these inhibitors do not bind Mcl-1 with as high affinity, and their ADS is a Leukemia and Lymphoma Society Scholar in Clinical Research. therapeutic potential is constrained by dose-limiting thrombocy- The authors thank Powered 4 Significance LLC for assistance with medical topenia associated with potent Bcl-XL inhibition in platelets [29]. writing in preparing an initial draft of the manuscript and editorial assistance. Obatoclax was developed as a promiscuous Bcl-2 family inhibitor and also inhibits Mcl-1, which is essential for development and sustained growth of AML [6]. Follow-on analysis of the correlation Author Contributions between anti-apoptotic Bcl-2 proteins and obatoclax response was Conceived and designed the experiments: ADS GB. Performed the not conducted in this study, and will be important to include in experiments: ADS AR THC DC HE DJD MST CG GB. Analyzed the future phase II evaluations. data: ADS AR THC DC GB. Contributed reagents/materials/analysis It is conceivable, given their mechanism of action, that Bcl-2 tools: ADS AR THC DC HE DJD MST GB. Wrote the paper: ADS AR family inhibitors might be most active in combination with other THC HE DJD MST CG. References 1. Estey E, Dohner H (2006) Acute myeloid leukaemia. Lancet 368: 1894–1907. 11. Hwang JJ, Kuruvilla J, Mendelson D, Pishvaian MJ, Deeken JF, et al. (2010) 2. Siegel R, Naishadham D, Jemal A (2013) Cancer statistics, 2013. CA Phase I dose finding studies of obatoclax (GX15-070), a small molecule pan- Cancer J Clin 63: 11–30. BCL-2 family antagonist, in patients with advanced solid tumors or lymphoma. Clin Cancer Res 16: 4038–4045. 3. National Cancer Institute. SEER Stat Fact Sheets: Leukemia. Available: http:// seer.cancer.gov/statfacts/html/leuks.html. Accessed: 2014 Apr 17. 12. O’Brien SM, Claxton DF, Crump M, Faderl S, Kipps T, et al. (2009) Phase I 4. Chipuk JE, Moldoveanu T, Llambi F, Parsons MJ, Green DR (2010) The BCL- study of obatoclax mesylate (GX15-070), a small molecule pan-Bcl-2 family 2 family reunion. Mol Cell 37: 299–310. antagonist, in patients with advanced chronic lymphocytic leukemia. Blood 113: 5. Cory S, Adams JM (2002) The Bcl2 family: regulators of the cellular life-or- 299–305. death switch. Nat Rev Cancer 2: 647–656. 13. Oki Y, Copeland A, Hagemeister F, Fayad LE, Fanale M, et al. (2012) 6. Glaser SP, Lee EF, Trounson E, Bouillet P, Wei A, et al. (2012) Anti-apoptotic Experience with obatoclax mesylate (GX15-070), a small molecule pan-Bcl-2 Mcl-1 is essential for the development and sustained growth of acute myeloid family antagonist in patients with relapsed or refractory classical Hodgkin leukemia. Genes Dev 26: 120–125. lymphoma. Blood 119: 2171–2172. 7. Willis SN, Fletcher JI, Kaufmann T, van Delft MF, Chen L, et al. (2007) 14. Schimmer AD, O’Brien S, Kantarjian H, Brandwein J, Cheson BD, et al. (2008) Apoptosis initiated when BH3 ligands engage multiple Bcl-2 homologs, not Bax A phase I study of the pan bcl-2 family inhibitor obatoclax mesylate in patients or Bak. Science 315: 856–859. with advanced hematologic malignancies. Clin Cancer Res 14: 8295–8301. 8. Nguyen M, Marcellus RC, Roulston A, Watson M, Serfass L, et al. (2007) Small 15. Parikh SA, Kantarjian H, Schimmer A, Walsh W, Asatiani E, et al. (2010) Phase molecule obatoclax (GX15-070) antagonizes MCL-1 and overcomes MCL-1- II study of obatoclax mesylate (GX15-070), a small-molecule BCL-2 family mediated resistance to apoptosis. Proc Natl Acad Sci U S A 104: 19512–19517. antagonist, for patients with myelofibrosis. Clin Lymphoma Myeloma Leuk 10: 9. Zhai D, Jin C, Satterthwait AC, Reed JC (2006) Comparison of chemical 285–289. inhibitors of antiapoptotic Bcl-2-family proteins. Cell Death Differ 13: 1419– 16. Raza A, Galili N, Borthakur G, Carter TH, Claxton DF, et al. (2009) A safety and schedule seeking trial of Bcl-2 inhibitor obatoclax in previously untreated 10. Konopleva M, Watt J, Contractor R, Tsao T, Harris D, et al. (2008) older patients with acute myeloid leukemia (AML). J Clin Oncol 27: suppl; abstr Mechanisms of antileukemic activity of the novel Bcl-2 homology domain-3 mimetic GX15-070 (obatoclax). Cancer Res 68: 3413–3420. PLOS ONE | www.plosone.org 9 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML 17. National Cancer Instititute. Common Terminology Criteria for Adverse Events 25. Rooswinkel RW, van de Kooij B, Verheij M, Borst J (2012) Bcl-2 is a better ABT-737 target than Bcl-xL or Bcl-w and only Noxa overcomes resistance v3.0 (CTCAE). Available: http://ctep.cancer.gov/protocolDevelopment/ mediated by Mcl-1, Bfl-1, or Bcl-B. Cell Death Dis 3: e366. electronic_applications/docs/ctcaev3.pdf. Accessed: 2014 Apr 17. 26. Tse C, Shoemaker AR, Adickes J, Anderson MG, Chen J, et al. (2008) ABT-263: 18. Cheson BD, Bennett JM, Kopecky KJ, Buchner T, Willman CL, et al. (2003) a potent and orally bioavailable Bcl-2 family inhibitor. Cancer Res 68: 3421– Revised recommendations of the International Working Group for Diagnosis, Standardization of Response Criteria, Treatment Outcomes, and Reporting 27. Roberts AW, Seymour JF, Brown JR, Wierda WG, Kipps TJ, et al. (2012) Standards for Therapeutic Trials in Acute Myeloid Leukemia. J Clin Oncol 21: Substantial susceptibility of chronic lymphocytic leukemia to BCL2 inhibition: 4642–4649. results of a phase I study of navitoclax in patients with relapsed or refractory 19. Li H, Chen Y, Jones AF, Sanger RH, Collis LP, et al. (2008) Bcl-xL induces disease. J Clin Oncol 30: 488–496. Drp1-dependent synapse formation in cultured hippocampal neurons. Proc Natl 28. Wilson WH, O’Connor OA, Czuczman MS, LaCasce AS, Gerecitano JF, et al. Acad Sci U S A 105: 2169–2174. (2010) Navitoclax, a targeted high-affinity inhibitor of BCL-2, in lymphoid 20. Offen D, Beart PM, Cheung NS, Pascoe CJ, Hochman A, et al. (1998) malignancies: a phase 1 dose-escalation study of safety, pharmacokinetics, Transgenic mice expressing human Bcl-2 in their neurons are resistant to 6- pharmacodynamics, and antitumour activity. Lancet Oncol 11: 1149–1159. hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine neurotox- 29. Vogler M, Hamali HA, Sun XM, Bampton ET, Dinsdale D, et al. (2011) BCL2/ icity. Proc Natl Acad Sci U S A 95: 5789–5794. BCL-X(L) inhibition induces apoptosis, disrupts cellular calcium homeostasis, 21. Paik PK, Rudin CM, Pietanza MC, Brown A, Rizvi NA, et al. (2011) A phase II and prevents platelet activation. Blood 117: 7145–7154. study of obatoclax mesylate, a Bcl-2 antagonist, plus topotecan in relapsed small 30. Brem EA, Thudium K, Khubchandani S, Tsai PC, Olejniczak SH, et al. (2011) cell lung cancer. Lung Cancer 74: 481–485. Distinct cellular and therapeutic effects of obatoclax in rituximab-sensitive and - 22. Dewson G, Kluck RM (2010) Bcl-2 family-regulated apoptosis in health and resistant lymphomas. Br J Haematol 153: 599–611. disease. Cell Health Cytoskel 2: 9–22. 31. Campas C, Cosialls AM, Barragan M, Iglesias-Serret D, Santidrian AF, et al. 23. Thomas M, Gessner A, Vornlocher HP, Hadwiger P, Greil J, et al. (2005) (2006) Bcl-2 inhibitors induce apoptosis in chronic lymphocytic leukemia cells. Targeting MLL-AF4 with short interfering RNAs inhibits clonogenicity and Exp Hematol 34: 1663–1669. engraftment of t(4;11)-positive human leukemic cells. Blood 106: 3559–3566. 32. Rahmani M, Aust MM, Attkisson E, Williams DC, Jr., Ferreira-Gonzalez A, et 24. Izon DJ, Rozenfeld S, Fong ST, Komuves L, Largman C, et al. (1998) Loss of al. (2012) Inhibition of Bcl-2 antiapoptotic members by obatoclax potently function of the homeobox gene Hoxa-9 perturbs early T-cell development and enhances sorafenib-induced apoptosis in human myeloid leukemia cells through induces apoptosis in primitive thymocytes. Blood 92: 383–393. a Bim-dependent process. Blood 119: 6089–6098. PLOS ONE | www.plosone.org 10 October 2014 | Volume 9 | Issue 10 | e108694 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png PLoS ONE Pubmed Central

A Multicenter Phase I/II Study of Obatoclax Mesylate Administered as a 3- or 24-Hour Infusion in Older Patients with Previously Untreated Acute Myeloid Leukemia

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© 2014 Schimmer et al
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1932-6203
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10.1371/journal.pone.0108694
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Abstract

Purpose: An open-label phase I/II study of single-agent obatoclax determined a maximum tolerated dose (MTD) and schedule, safety, and efficacy in older patients ($70 yr) with untreated acute myeloid leukemia (AML). Experimental Design: Phase I evaluated the safety of obatoclax infused for 3 hours on 3 consecutive days (3 h63d) in 2- week cycles. Initial obatoclax dose was 30 mg/day (3 h63 d; n = 3). Obatoclax was increased to 45 mg/day (3 h63d) if #1 patient had a dose-limiting toxicity (DLT) and decreased to 20 mg/day (3 h63 d) if DLT occurred in $2 patients. In the phase II study, 12 patients were randomized to receive obatoclax at the dose identified during phase I (3 h63 d) or 60 mg/ day administered by continuous infusion over 24 hours for 3 days (24 h63 d) to determine the morphologic complete response rate. Results: In phase I, two of three patients receiving obatoclax 30 mg/day (3 h63 d) experienced grade 3 neurologic DLTs (confusion, ataxia, and somnolence). Obatoclax was decreased to 20 mg/day (3 h63 d). In phase II, no clinically relevant safety differences were observed between the 20 mg/day (3 h63 d; n = 7) and 60 mg/day (24 h63 d; n = 5) arms. Neurologic and psychiatric adverse events were most common and were generally transient and reversible. Complete response was not achieved in any patient. Conclusions: Obatoclax 20 mg/day was the MTD (3 h63 d) in older patients with AML. In the schedules tested, single-agent obatoclax was not associated with an objective response. Evaluation in additional subgroups or in combination with other chemotherapy modalities may be considered for future study. Trial Registration: ClinicalTrials.gov NCT00684918 Citation: Schimmer AD, Raza A, Carter TH, Claxton D, Erba H, et al. (2014) A Multicenter Phase I/II Study of Obatoclax Mesylate Administered as a 3- or 24-Hour Infusion in Older Patients with Previously Untreated Acute Myeloid Leukemia. PLoS ONE 9(10): e108694. doi:10.1371/journal.pone.0108694 Editor: Maria R. Baer, University of Maryland, United States of America Received May 16, 2014; Accepted August 19, 2014; Published October 6, 2014 Copyright:  2014 Schimmer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All data are included within the paper. Funding: The study that is the subject of this manuscript was sponsored by Gemin X Pharmaceuticals, Inc., which was acquired by Cephalon, Inc., a wholly- owned subsidiary of Teva Pharmaceutical Industries, Ltd (TEVA). The development and publication of this manuscript has been financially supported by TEVA. Employees of TEVA were actively involved in the development of the manuscript, including providing data as well as review and comment of manuscript drafts. Powered 4 Significance LLC was contracted by TEVA to provide medical writing assistance in preparing an initial draft of the manuscript and editorial assistance. Competing Interests: The authors have read the journal’s policy and have the following competing interests: ADS, GB, and THC report research support from GeminX, during the conduct of the study; HE reports compensation from Celgene, Novartis, Celator, Sunesis, Seattle Genetics, and Incyte, outside the submitted work; AR, DC, DJD, CG, and MST have no competing interests to declare. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials. * Email: aaron.schimmer@utoronto.ca States, a total of 14,590 new AML diagnoses were projected to Introduction occur in 2013, with an estimated 10,370 deaths [2]. AML is Acute myeloid leukemia (AML) is a heterogeneous hematologic predominantly a disease of older adults with a median age at malignancy that results from the clonal expansion of primitive diagnosis of 66 years [3]. Compared with younger patients (,55 myeloid precursor cells [1]. AML is the most common form of years), AML in older patients ($55 years) is more frequently acute leukemia in adults, and has a high mortality. In the United PLOS ONE | www.plosone.org 1 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Figure 1. Study design. CR, complete response; DLT, dose-limiting toxicity. doi:10.1371/journal.pone.0108694.g001 associated with a poor prognosis, in part due to decreased response suggested that a subset of treatment-naive patients with AML might benefit from obatoclax therapy. rates and increased toxicity of standard induction chemotherapy. Consequently, there is an unmet need for therapies that provide Continuous infusion of obatoclax 60 mg/day for 3 days (24 h63 d) in 2-week cycles has previously been evaluated in efficacy and favorable tolerability in older patients with AML. phase II trials in patients with myelofibrosis or Hodgkin’s Development of small-molecule inhibitors specific for anti- lymphoma [13,15]. An accelerated 3-hour infusion, 3-day apoptotic proteins is a novel approach to the treatment of (3 h63 d) regimen has not yet been evaluated in a 2-week cycle hematologic cancers. Anti-apoptotic B cell-chronic lymphocytic in patients with hematologic malignancies, nor have these leukemia/lymphoma 2 (Bcl-2) family members (Bcl-2, Bcl-XL, regimens been formally compared. The objectives of this Bcl-w, Bcl-b, A1/Bfl-1, and Mcl-1) are overexpressed in many multicenter phase I/II study were to expand on previous cancers and inhibit apoptosis by sequestering pro-apoptotic experiences with obatoclax and to evaluate the dose and schedule members of the family (BH3-only proteins, and Bax and Bak) of single-agent obatoclax for safety and efficacy in older patients [4,5]. Importantly, emerging evidence suggests that anti-apoptotic with previously untreated AML. Mcl-1 is critical for sustained survival and expansion of human AML and plays a role in drug resistance in this disease [6]. Since Patients and Methods interactions between anti- and pro-apoptotic family members are mediated by the BH3 domain protein interaction motif [4,5], Study Design small molecules that bind to the BH3 binding groove may induce An open-label, multicenter, phase I/II study was conducted. apoptosis by inhibiting sequestration of pro-apoptotic factors [7]. The protocol for this trial and supporting CONSORT checklist Obatoclax mesylate (obatoclax, also known as GX15-070) is a are available as supporting information; see Checklist S1 and novel anticancer therapeutic for hematologic malignancies and Protocol S1. The phase I portion of the study consisted of a solid tumors. The compound, which acts as a BH3 mimetic, was nonrandomized safety evaluation, followed by a randomized phase developed as a pan-inhibitor of anti-apoptotic members of the Bcl- II evaluation of different treatment schedules (Figure 1). The 2 family, including Mcl-1, to trigger cell death [8,9]. Preclinical phase I safety evaluation assessed obatoclax as a 3-hour infusion investigations demonstrated that obatoclax induces apoptosis and over 3 consecutive days (3 h63 d). Because the optimal schedule reduces proliferation in AML cell lines and primary AML cells, in for obatoclax treatment was unknown, the phase II evaluation part by inhibition of Mcl-1 sequestration of Bax [10]. utilized a randomized open-label design to assess 3-hour or 24- In phase I trials of single-agent obatoclax, antitumor activity was hour infusion schedules, over 3 consecutive days (3 h63d or observed in several hematologic malignancies, including AML, 24 h63 d). The selected dose for the 24-hour infusion was the myelodysplastic syndrome, and Hodgkin’s and non-Hodgkin’s previously defined maximum tolerated dose (MTD) of 60 mg/day lymphoma [11–14]. Although there were a limited number of [16]. objective responses in these early clinical studies, hematologic improvement was observed in a larger proportion of treated Ethics Statement patients. One striking clinical response occurred in a 70-year-old The study was conducted in accordance with the October 2000 woman with previously untreated AML who achieved a complete version of the Declaration of Helsinki, as well as Good Clinical response (CR) after receiving 20 mg/m obatoclax as a 24-hour Practice and International Conference on Harmonisation guide- infusion [14]. Her CR was maintained over 8 months and lines. An accredited institutional review board approved this study PLOS ONE | www.plosone.org 2 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML prior to its initiation and all patients provided informed written antibiotics, IV immunoglobulins, and hematopoietic growth consent. This study was registered at clinicaltrials.gov factors. (NCT00684918). Endpoints and Assessments Patient Eligibility Endpoints. Safety endpoints included number of DLTs, Patients at least 70 years of age with histologically confirmed treatment-emergent AEs, including serious AEs, and clinical AML were eligible to participate. In the phase I portion of the laboratory values. AEs were recorded according to the National study, patients may have received one previous therapy. In the Cancer Institute Common Terminology Criteria for Adverse phase II portion of the study, no prior therapy for AML was Events, version 3.0 [17]. allowed except for hydroxyurea. Additional eligibility require- Clinical response was assessed using standard criteria [18]. The ments included Eastern Cooperative Oncology Group (ECOG) primary efficacy endpoint was rate of morphologic CR, or performance status #2 and normal hepatic and renal function cytogenetic CR in patients with abnormal cytogenetics at baseline. (total bilirubin #2 mg/dL unless resulting from hemolysis; Morphologic CR was defined as neutrophils .1000/mL, platelets aspartate transaminase/alanine transaminase #2.56 institutional .100,000/mL, and bone marrow blasts ,5%. Cytogenetic CR upper limit of normal; creatinine within normal institutional limits was defined as neutrophils .1000/mL, platelets .100,000/mL, or creatinine clearance $50 mL/min/1.73 m for patients with bone marrow blasts ,5%, and normal cytogenetics. Additional creatinine levels above institutional normal). efficacy endpoints included molecular CR, partial remission (PR), Patients were excluded if they had a history of allergy to and morphologic leukemia-free state, and change in bone marrow components of the formulated product. Comorbidities requiring blasts from baseline to post-induction therapy (day 28). patient exclusion included a history of seizure disorder or central Schedule of assessments. AEs were recorded from baseline nervous system leukemia or other symptomatic neurologic illness; screening to 28 days after the last obatoclax dose. Complete blood uncontrolled systemic infection considered opportunistic, life- counts (absolute neutrophil count, lymphocytes, monocytes, threatening, or clinically significant; symptomatic congestive heart eosinophils, and basophils) were obtained on day 1 of each cycle, failure; unstable angina pectoris; cardiac arrhythmia; significant every 2–3 days for the first week of cycle 1, and on day 8 of each pulmonary disease or hypoxia; psychiatric illness/social situation cycle. Physical and neurologic examinations, including vital signs, that would limit compliance with study requirements; or infection body weight, ECOG performance status, and serum chemistries with human immunodeficiency virus. were performed at baseline and on days 1 and 8 of each cycle. Chest radiographs, pulmonary function tests, and urinalysis were conducted at baseline and at the 28-day follow-up visit. An Treatments electrocardiogram was obtained at baseline, 30 minutes before the Obatoclax mesylate (30 mg) was diluted with 5% dextrose, USP end of infusion on day 3 in cycle 1, and at the 28-day follow-up and a final concentration of 11.54% polyethylene glycol 300, visit, and repeated as clinically indicated. 0.46% polysorbate 20 for intravenous (IV) infusion. Treatments Bone marrow aspirates and biopsies were conducted at baseline, were evaluated as depicted in Figure 1. In the phase I portion of on day 28, after obatoclax consolidation therapy, and as clinically the study, the first 3 patients enrolled received obatoclax 30 mg/ indicated. CR was documented by repeat bone marrow exami- day over 3 hours for 3 consecutive days (3 h63 d). Dose-limiting nation on day 28 or earlier. Bone marrow cytogenetics were toxicities (DLTs) were defined as grade $3 infusion-related assessed at baseline, repeated on occurrence of CR, and as neurologic adverse events (AEs) and nonhematologic AEs not clinically indicated. responsive to symptom-directed therapy. If (during cycle 1) #1of the 3 patients experienced a DLT, subsequent enrolled patients would receive 45 mg/day for 3 consecutive days (3 h63 d). If, Statistical Analysis however, $2 of 3 patients experienced a DLT, an additional Safety was assessed in all patients who received any amount of group of 3 patients would be enrolled and would receive 20 mg/ study drug per National Cancer Institute Common Terminology day over 3 hours for 3 consecutive days (3 h63 d). If #1of3 Criteria for Adverse Events, version 3. Efficacy was assessed in all patients experienced a DLT at 20 mg/day, this dose would be patients with at least one post-baseline efficacy assessment. All utilized for the 3 h63 d phase II study. If $2 of the 3 patients outcomes were summarized descriptively. For categorical vari- experienced a DLT at 20 mg/day, the 3 h63 d schedule would be ables, summary tabulations of the number and percentage in each halted, and the phase II study would use only the 24 h63d parameter were provided. For continuous variables, the mean, schedule for obatoclax administration, which has previously been median, standard deviation, minimum, and maximum were shown to be well tolerated and produced a CR in a patient with presented. To determine the rate of morphologic CR, a two-stage AML [14]. design was used, powered to detect a CR rate of $15% against a In the phase II portion of the study, patients were randomized non-interesting rate of 5%, with alpha = 0.05 and a power of (1:1) into two arms. One arm received obatoclax at the dose 90%. Stage 1 was to enroll 37 patients under this design, and if $3 identified from phase I at 3 h63 d; the other arm received 60 mg/ patients achieved CR at the end of Stage 1, an additional 47 day (24 h63 d). In both phases, obatoclax was administered in patients would be enrolled. two 2-week cycles as induction therapy. Any patient achieving a CR could receive four additional treatment cycles as consolidation Results therapy every 2 weeks for a total of six cycles of obatoclax treatment. Patients who did not achieve CR after two cycles of Demographics and Patient Disposition obatoclax were to be removed from study. A total of 19 patients were enrolled in the study from March Prophylaxis with H-1 and H-2 blockers was recommended prior 2008 to March 2009; one patient did not receive obatoclax to each cycle, given the known prevalence of acute hypersensitivity treatment. Demographics and disease characteristics were similar reactions associated with obatoclax exposure [14]. Full supportive across all regimens (Table 1). Overall, the mean age was 81 years care was offered to treat acute nausea, vomiting, or DLTs as (range 72–90 years). The median time from AML diagnosis to appropriate, including anti-emetic prophylaxis, blood products, study entry was 0.6 months (range 0–37 months). Most (56%) PLOS ONE | www.plosone.org 3 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Table 1. Demographics and baseline characteristics of obatoclax-treated patients (N = 18). Phase I Phase II All (N = 18) 30 mg/d (3 h63d) 20 mg/d (3 h63d) 20 mg/d (3 h63d) 60 mg/d (24 h63d) (n = 3) (n = 3) (n = 7) (n = 5) Median (range) age, years 83 (81–85) 74 (72–90) 82 (72–89) 80 (76–86) 81.5 (72–90) Male, n (%) 1 (33) 1 (33) 3 (43) 3 (60) 8 (44) ECOG PS, n (%) 0 1 (33) 0 3 (43) 1 (20) 5 (28) 1 1 (33) 1 (33) 4 (57) 2 (40) 8 (44) 2 1 (33) 2 (67) 0 2 (40) 5 (28) Median time since AML diagnosis, 1 (0.5–7.4) 1.2 (1–16.7) 0.45 (20.2–0.6) 0.2 (0–37.2) 0.6 (20.2–37.2) months (range) AML classification, n (%) M1 1 (33) 0 3 (43) 0 4 (22) M2 2 (67) 1 (33) 3 (43) 4 (80) 10 (56) M3 0 1 (33)* 0 0 1 (6) M4 0 1 (33) 0 1 (20) 2 (11) Missing 0 0 1 (14) 0 1 (6) Cytogenetics, n (%) Abnormal 1 (33) 3 (100) 3 (43) 3 (60) 10 (56) Normal 1 (33) 0 2 (29) 2 (40) 5 (28) Missing 1 (33) 0 2 (29) 0 3 (17) Median leukocyte count (range), 10 /mL 1.3 (0.5–1.4) 29.2 (19.3–64.3) 4.3 (1.1–7.3) 2.8 (1.1–27.2) 4.25 (0.5–64.3) Median platelet count (range), 10 /mL 23 (8–154) 126 (69–227) 63 (19–518) 63 (19–259) 66 (8–518) Median hemoglobin (range), g/L 86 (86–102) 105 (99–110) 101 (86–117) 93 (90–100) 97.5 (86–117) 3 a b c d e Median neutrophil count (range), 10 /mL 0.2 (0.2–0.2) 1.95 (0.6–3.3) 0.39 (0.1–2.6) 6.98 (0.5–13.5) 0.55 (0.1–13.5) *Classified as acute promyelocytic leukemia. Evaluated in 1 patient. Evaluated in 2 patients. Evaluated in 5 patients. Evaluated in 2 patients. Evaluated in 10 patients. AML, acute myeloid leukemia; ECOG PS, Eastern Cooperative Oncology Group performance status. doi:10.1371/journal.pone.0108694.t001 patients had a French-American-British classification of M2; the Safety distribution of AML classification was similar for all regimens. In the phase I safety study, two of three patients treated with Approximately 56% of patients had an abnormal karyotype; 30 mg/day (3 h63 d) experienced grade 3 neurologic events that further details of the cytogenetic abnormalities were not available, led to discontinuation of treatment and were classified as DLTs thus precluding classification of cytogenetics into risk groups. (Table 3). The first patient experienced grade 3 somnolence (day Patient disposition is shown in Figure 2. The most common 1) and grade 3 confusion. This patient also experienced dizziness, reasons for withdrawal from the study were failure to achieve CR mood alteration, and speech disorder during infusion (all grade , following induction therapy (eight patients, 42%), adverse events 3; Table 4). The second patient experienced grade 3 ataxia and (including DLT; four patients, 21%), and disease progression grade 1 confusion, euphoria, and somnolence on day 1 of cycle 1. (three patients, 16%). Two patients were granted waivers for In both patients, neurologic DLTs were assessed as definitely laboratory abnormalities (hyperuricemia) at baseline. related to study drug and resolved within 24 hours. The third The number of treatment cycles administered in the phase I/II patient in this group also experienced euphoria and ataxia (grade studies is shown in Table 2. Overall, the median number of ,3) and discontinued due to leukemic infiltrate. One serious AE cycles administered was two (range 1–11). In both the phase I and (grade 3 neutropenic fever) was reported for this regimen, but was II studies, a total of 15 patients (83%) were treated for at least two judged to be unrelated to study drug (Table 3). cycles. Four patients also received additional treatment cycles as Per protocol, the obatoclax dose in the 3 h63 d regimen was consolidation therapy as they experienced disease stabilization or decreased to 20 mg/day in a subsequent cohort of three patients. decreased blast counts in the marrow, although these continued No additional DLTs were observed in this group and only one cycles were considered protocol deviations. Of these four patients, grade 3 serious AE (pneumonia) was reported and was considered one patient received a total of eight cycles of therapy, two patients unrelated to study drug. In addition, one patient experienced received a total of four cycles, and one patient received a total of grade 2 cytokine release syndrome, which was also considered a serious AE (Table 3). Therefore, the 20 mg/day (3 h63d) 11 cycles. regimen was chosen for the randomized phase II portion of the PLOS ONE | www.plosone.org 4 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Figure 2. Patient disposition. AE, adverse event; CR, complete response. doi:10.1371/journal.pone.0108694.g002 study for comparison with obatoclax 60 mg/day (24 h63 d), as obatoclax. Acute myocardial infarction resulted in treatment previously defined in a small study of 18 patients [16]. discontinuation in one patient. In the phase II study, most patients receiving either obatoclax Combining both the phase I and II components of the study, all 20 mg/day (3 h63 d) or 60 mg/day (24 h63 d) experienced mild 18 (100%) patients who received obatoclax experienced at least 1 to moderate (grade ,3), transient, neurologic AEs such as AE, the most common of which were neurologic (n = 14; 77.8%) euphoria, somnolence, ataxia, dizziness, and confusion (Table 4). or psychiatric (n = 16; 88.9%); most were transient and mild, and AEs of grade $3 that were reported in more than one patient resolved without sequelae. Ten patients experienced serious AEs; included febrile neutropenia (n = 3), dizziness (n = 2), atrial details are provided in Table 3. Evidence for trends between fibrillation (n = 2), and acute myocardial infarction (n = 2). The severity of AEs (grade $3) and dose or schedule was not observed events of dizziness, atrial fibrillation, and acute myocardial (Table 4). AEs (any grade) with the highest reported incidence infarction were considered to be at least possibly related to included euphoria (67%), somnolence (44%), and ataxia (39%). Table 2. Study drug exposure in patients treated with obatoclax (N = 18). Phase I Phase II All (N = 18) 3-h infusion (20 mg/d) 24-h infusion (60 mg/d) 30 mg/d (n = 3) 20 mg/d (n = 3) (n = 7) (n = 5) Median number of cycles (range) 2 (1–2) 4 (4–8) 2 (2–11) 2 (1–2) 2 (1–11) Total cycles, n (%) 1 3 (100) 3 (100) 7 (100) 5 (100) 18 (100) 2 2 (67) 3 (100) 7 (100) 3 (60) 15 (83) 3 0 3 (100) 1 (14) 0 4 (22) 4 0 3 (100) 1 (14) 0 4 (22) 5 0 1 (33) 1 (14) 0 2 (11) 6 0 1 (33) 1 (14) 0 2 (11) 7 0 1 (33) 1 (14) 0 2 (11) 8 0 1 (33) 1 (14) 0 2 (11) .9 0 0 1 (14) 0 1 (6) doi:10.1371/journal.pone.0108694.t002 PLOS ONE | www.plosone.org 5 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML Table 3. Summary of dose-limiting toxicities and serious adverse events. Phase I Phase II 3-h infusion (20 mg/d) 24-h infusion (60 mg/d) 30 mg/d (n = 3) 20 mg/d (n = 3) (n = 7) (n = 5) Dose-limiting toxicity Grade 3 somnolence/confusion 00 0 (1); grade 3 ataxia (1) Serious TEAE, n (grade, attribution) Febrile neutropenia 1 (gr 3, NR) 1 (gr 3, NR) Atrial fibrillation 2 (gr 3, NR; gr 3, NR) Acute myocardial infarction 1 (gr 3, NR) 1 (gr 4, PS) Cough 2 (gr 1, NR; gr 2, PS) Catheter site infection 1 (gr 3, NR) 1 (gr 3, NR) Cytokine release syndrome 1 (gr 2, PR) Pneumonia 1 (gr 3, NR) 1 (gr 3, NR) Acute sinusitis 1 (gr 1, NR) Dyspnea 1 (gr 2, NR) Fatigue 1 (gr 5, NR) Dizziness 1 (gr 3, PR) AE, adverse event; DLT, dose-limiting toxicity (DLTs were defined as grade $3 infusion-related neurologic AEs and nonhematologic AEs not responsive to symptom- directed therapy); PR, probably related; PS, possibly related; NR, not related; TEAE, treatment-emergent adverse event. doi:10.1371/journal.pone.0108694.t003 Somnolence was the most commonly reported grade $3AE weeks) by 3-hour or 24-hour infusion was generally mild and (17%). The most common grade $3 toxicities based on laboratory similar to previous reports [11–14]. AEs were typically transient, data were leukocytosis and thrombocytopenia (each n = 9). No neurologic, or psychiatric findings that resolved without sequelae. clinically meaningful differences were observed across regimens for Based on the safety profile, 20 mg/day was determined to be the laboratory reports of grade $3 hematologic findings. MTD of obatoclax when administered over 3 hours/day for 3 Two patients died during the study for reasons unrelated to consecutive days in older AML patients. Two patients treated with obatoclax administration. One patient on the 60 mg/day the 30 mg/day (3 h63 d) regimen experienced DLTs consisting of (24 h63 d) regimen died on day 23 of the study from progressive grade 3 confusion, somnolence, or ataxia, which led to premature disease. The second patient, receiving 20 mg/day (3 h63 d), died discontinuation and selection of the 20 mg/day dose for further on day 41; the cause of death is unknown. An additional six evaluation. In the phase II comparison of obatoclax 20 mg/day patients died more than 30 days after the last obatoclax dose. (3 h63 d) to the previously evaluated 60 mg/day (24 h63d) Causes of death in these patients were progressive disease (n = 2), regimen, both dosing schedules demonstrated similar safety sepsis (n = 1), and unknown (n = 3). profiles. The mechanism(s) underlying the development of neurologic or Efficacy psychiatric symptoms is uncertain. However, it is plausible that CR was not achieved with obatoclax induction. However, three these symptoms represent an on-target effect, since Bcl-2 promotes patients on the 20 mg/day (3 h63 d) regimen demonstrated a 7% neuron survival and Bcl-XL plays a role in synaptic plasticity to 17% decrease in bone marrow blast percentage between the [19,20]. Alternatively, the neurologic and psychiatric effects of baseline assessment and the end of cycle 2 (Table 5). It is obatoclax may reflect binding to targets other than Bcl-2 family noteworthy that two of these patients with decreased marrow members. blasts also demonstrated an increase of 33% to 57% in neutrophil Based on laboratory data, grade $3 leukocytosis and throm- count. Of these three patients, one patient in phase I receiving bocytopenia occurred in 50% of patients in this study. These obatoclax 20 mg/day (3 h63 d arm) had a decrease in marrow hematologic abnormalities are likely related to underlying disease blasts from 27% to 10% with increased neutrophils from rather than obatoclax as they were present at baseline. However, it 3 3 9344610 /mL to 14,700610 /mL. This patient received eight should be noted that inhibition of Bcl-XL by obatoclax may result cycles of study treatment and withdrew from the study on the in thrombocytopenia. Because patients also received platelet advice of the investigator. One additional patient in the phase II transfusions during the study as supportive care, the impact of portion of the study had increased neutrophil (pre-treatment: 3 3 obatoclax on platelet production may have been obscured. 230610 /mL; end of cycle 2: 2500610 /mL) and platelet counts 3 3 Six patients experienced cardiac events during this study, four of (pre-treatment: 73610 /mL; end of cycle 2: 250610 /mL) without which were assessed as at least possibly related to the study drug. a significant change in the marrow blasts. This patient remained The causal relationship with ischemic cardiac events, if any, is stable and received 11 cycles of obatoclax. unclear because patients in this study were older with multiple comorbidities. In other clinical studies evaluating obatoclax, QTc Discussion prolongation has been reported by automated electrocardiogram. The results of the current study demonstrate that the safety In a study of patients with relapsed small cell lung cancer, the profile of obatoclax administered for 3 consecutive days (every 2 interval between obatoclax doses was extended to 3 days in a PLOS ONE | www.plosone.org 6 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML PLOS ONE | www.plosone.org 7 October 2014 | Volume 9 | Issue 10 | e108694 Table 4. Treatment-emergent adverse events occurring in more than one patient. Phase II 3-h infusion (20 mg/d) Phase II 24-h infusion (60 mg/d) Phase I 20 mg/d (n = 3) Phase I 30 mg/d (n = 3) (n = 7) (n = 5) All (N = 18) n All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 Euphoria 3 0 2 0 6 1 1 0 12 1 Somnolence 0 0 2 2 4 1 2 0 8 3 Ataxia 0 0 3 1 3 0 1 1 7 2 Dizziness 1 0 1 0 2 1 1 1 5 2 Confusion 0 0 2 1 1 0 2 0 5 1 Constipation 1 0 1 3 5 Fever 0 0 0 0 3 1 2 0 5 1 Diarrhea 1 1 1 1 4 Peripheral edema 0 0 2 2 4 Febrile neutropenia 0 0 1 1 2 2 1 1 4 4 Disorientation 2 0 1 0 3 Cough 0 1 2 0 3 Unsteady gait 0 1 2 0 3 Insomnia 1 0 2 0 3 Dyspnea 0 0 1 2 3 Hypoxia 00 00 31 0 0 31 Dysarthria 1 0 2 0 3 Fatigue 0 0 0 0 2 0 1 1 3 1 Headache 0 0 2 1 3 Ecchymosis 0 0 3 0 3 Hypotension 0 0 1 1 2 Tachycardia 0 0 2 0 2 Cardiac murmur 0 0 2 0 2 Atrial fibrillation 0 0 0 0 2 2 0 0 2 2 Pneumonia 1 1 0 0 1 1 0 0 2 2 Loose stool 1 0 1 0 2 Gingival pain 0 1 1 0 2 Cytokine release syndrome 1 0 1 0 2 Abnormal breath sounds 0 0 1 1 2 AcuteMI 0 00 0 1 11 12 2 Dry mouth 0 0 1 1 2 Crackles (lung) 0 0 1 1 2 Thrush 0 0 2 0 2 Obatoclax in Older Patients with Untreated AML PLOS ONE | www.plosone.org 8 October 2014 | Volume 9 | Issue 10 | e108694 Table 4. Cont. Phase II 3-h infusion (20 mg/d) Phase II 24-h infusion (60 mg/d) Phase I 20 mg/d (n = 3) Phase I 30 mg/d (n = 3) (n = 7) (n = 5) All (N = 18) n All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 All grade Grade $3 Hypocalcemia 0 1 1 0 2 Hypokalemia 0 1 1 0 2 Slurred speech 0 0 2 0 2 Agitation 0 0 0 0 1 1 1 0 2 1 Muscular weakness 0 0 1 1 2 Anxiety 0 1 1 0 2 doi:10.1371/journal.pone.0108694.t004 Table 5. Improvement in marrow blast count, neutrophil count, and platelet count in patients receiving obatoclax. 3 3 Blast count, % (aspirate) Neutrophils, 610 /mL Platelets, 610 /mL Patient Treatment (phase) AML Classification Base-line End Cycle 2 Baseline End Cycle 2 Baseline End Cycle 2 04.002* 20 mg/d (I) M4 27 10 9344 14,700 227 206 04.003 20 mg/d (I) M3 27 20 3300 4400 126 139 05.002 20 mg/d (II) M1 33 23 390 360 49 47 *Received eight cycles of obatoclax. AML, acute myeloid leukemia. doi:10.1371/journal.pone.0108694.t005 Obatoclax in Older Patients with Untreated AML single patient who experienced QTc prolongation during the first inducers of cell death. For example, obatoclax induced apoptosis cycle [14,21]. In another phase I dose escalation study in advanced in OCI-AML3 leukemic cells when used in combination with hematologic malignancies, grade 3 QTc prolongation was ABT-737 and synergistically induced apoptosis in combination observed in 3 patients, but was confounded by the presence of with cytosine arabinoside in leukemic cell lines and in primary QTc prolongation at baseline [14]. Notably, an imbalance in the AML samples [10]. Preclinical investigations also suggest that ratio of anti-apoptotic to pro-apoptotic Bcl-2 proteins appears obatoclax potentiates the effect of established drugs in AML [30– causal in the development of cardiovascular disease, including 32], and several clinical trials of obatoclax combined with ischemic heart disease [22], so relationship to study drug cannot be conventional chemotherapeutic agents have been completed or excluded. are ongoing in a range of solid tumors and hematologic In the current study, four patients had a clinical response of malignancies (e.g., NCT00612612, NCT00521144 at clinical- stable disease and were treated for up to 11 cycles. We did not trials.gov). observe a CR in this study. This contrasts with our previous report In conclusion, based on the safety profile described in this study, of a CR achieved with single-agent obatoclax (20 mg/m over 20 mg/day is the MTD of obatoclax when administered by 3-hour 24 hours) in one older treatment-naive patient with AML with a infusion over 3 consecutive days in an older AML population, and mixed-lineage leukemia (MLL) t(9;11) translocation [14]. Al- it has similar tolerability to a 60 mg/day (24 h63 d) regimen. though such dramatic single-agent activity in previously untreated Although the current study does not support the efficacy of AML was not confirmed by our data, it is possible that MLL- obatoclax as a single agent in an unselected group of treatment- associated leukemia may be particularly sensitive to Bcl-2 family naive AML patients, additional studies may reveal activity in select inhibitors. Preclinical studies have shown that inhibition of MLL subgroups, particularly in combination with other chemothera- expression using siRNA corresponded with reduced Bcl-XL levels peutics. and leukemic proliferation that may be mediated by HoxA9 [23,24]. Thus, Bcl-2 proteins may play an important role in the Supporting Information proliferation of MLL-associated leukemia. In addition, a limitation of our study is that pharmacodynamic activity or pharmacokinetic Protocol S1 Study protocol for open-label phase I/II parameters were not assessed. Integrating these evaluations in study of single-agent obatoclax in older patients ($70 yr) future clinical trials of obatoclax may provide further insight into with untreated acute myeloid leukemia (AML). the clinical potential of obatoclax as a single agent. (PDF) In addition to obatoclax, several other small-molecule BH3 Checklist S1 CONSORT checklist. mimetics are under investigation. ABT-737 and ABT-263 (DOC) (navitoclax), for example, bind three of six Bcl-2 family members with high affinity [25,26]. Navitoclax has been evaluated in phase Acknowledgments I trials in lymphoid malignancies [27,28]. However, these inhibitors do not bind Mcl-1 with as high affinity, and their ADS is a Leukemia and Lymphoma Society Scholar in Clinical Research. therapeutic potential is constrained by dose-limiting thrombocy- The authors thank Powered 4 Significance LLC for assistance with medical topenia associated with potent Bcl-XL inhibition in platelets [29]. writing in preparing an initial draft of the manuscript and editorial assistance. Obatoclax was developed as a promiscuous Bcl-2 family inhibitor and also inhibits Mcl-1, which is essential for development and sustained growth of AML [6]. Follow-on analysis of the correlation Author Contributions between anti-apoptotic Bcl-2 proteins and obatoclax response was Conceived and designed the experiments: ADS GB. Performed the not conducted in this study, and will be important to include in experiments: ADS AR THC DC HE DJD MST CG GB. Analyzed the future phase II evaluations. data: ADS AR THC DC GB. Contributed reagents/materials/analysis It is conceivable, given their mechanism of action, that Bcl-2 tools: ADS AR THC DC HE DJD MST GB. Wrote the paper: ADS AR family inhibitors might be most active in combination with other THC HE DJD MST CG. References 1. Estey E, Dohner H (2006) Acute myeloid leukaemia. Lancet 368: 1894–1907. 11. Hwang JJ, Kuruvilla J, Mendelson D, Pishvaian MJ, Deeken JF, et al. (2010) 2. Siegel R, Naishadham D, Jemal A (2013) Cancer statistics, 2013. CA Phase I dose finding studies of obatoclax (GX15-070), a small molecule pan- Cancer J Clin 63: 11–30. BCL-2 family antagonist, in patients with advanced solid tumors or lymphoma. Clin Cancer Res 16: 4038–4045. 3. National Cancer Institute. SEER Stat Fact Sheets: Leukemia. Available: http:// seer.cancer.gov/statfacts/html/leuks.html. Accessed: 2014 Apr 17. 12. O’Brien SM, Claxton DF, Crump M, Faderl S, Kipps T, et al. (2009) Phase I 4. Chipuk JE, Moldoveanu T, Llambi F, Parsons MJ, Green DR (2010) The BCL- study of obatoclax mesylate (GX15-070), a small molecule pan-Bcl-2 family 2 family reunion. Mol Cell 37: 299–310. antagonist, in patients with advanced chronic lymphocytic leukemia. Blood 113: 5. Cory S, Adams JM (2002) The Bcl2 family: regulators of the cellular life-or- 299–305. death switch. Nat Rev Cancer 2: 647–656. 13. Oki Y, Copeland A, Hagemeister F, Fayad LE, Fanale M, et al. (2012) 6. Glaser SP, Lee EF, Trounson E, Bouillet P, Wei A, et al. (2012) Anti-apoptotic Experience with obatoclax mesylate (GX15-070), a small molecule pan-Bcl-2 Mcl-1 is essential for the development and sustained growth of acute myeloid family antagonist in patients with relapsed or refractory classical Hodgkin leukemia. Genes Dev 26: 120–125. lymphoma. Blood 119: 2171–2172. 7. Willis SN, Fletcher JI, Kaufmann T, van Delft MF, Chen L, et al. (2007) 14. Schimmer AD, O’Brien S, Kantarjian H, Brandwein J, Cheson BD, et al. (2008) Apoptosis initiated when BH3 ligands engage multiple Bcl-2 homologs, not Bax A phase I study of the pan bcl-2 family inhibitor obatoclax mesylate in patients or Bak. Science 315: 856–859. with advanced hematologic malignancies. Clin Cancer Res 14: 8295–8301. 8. Nguyen M, Marcellus RC, Roulston A, Watson M, Serfass L, et al. (2007) Small 15. Parikh SA, Kantarjian H, Schimmer A, Walsh W, Asatiani E, et al. (2010) Phase molecule obatoclax (GX15-070) antagonizes MCL-1 and overcomes MCL-1- II study of obatoclax mesylate (GX15-070), a small-molecule BCL-2 family mediated resistance to apoptosis. Proc Natl Acad Sci U S A 104: 19512–19517. antagonist, for patients with myelofibrosis. Clin Lymphoma Myeloma Leuk 10: 9. Zhai D, Jin C, Satterthwait AC, Reed JC (2006) Comparison of chemical 285–289. inhibitors of antiapoptotic Bcl-2-family proteins. Cell Death Differ 13: 1419– 16. Raza A, Galili N, Borthakur G, Carter TH, Claxton DF, et al. (2009) A safety and schedule seeking trial of Bcl-2 inhibitor obatoclax in previously untreated 10. Konopleva M, Watt J, Contractor R, Tsao T, Harris D, et al. (2008) older patients with acute myeloid leukemia (AML). J Clin Oncol 27: suppl; abstr Mechanisms of antileukemic activity of the novel Bcl-2 homology domain-3 mimetic GX15-070 (obatoclax). Cancer Res 68: 3413–3420. PLOS ONE | www.plosone.org 9 October 2014 | Volume 9 | Issue 10 | e108694 Obatoclax in Older Patients with Untreated AML 17. National Cancer Instititute. Common Terminology Criteria for Adverse Events 25. Rooswinkel RW, van de Kooij B, Verheij M, Borst J (2012) Bcl-2 is a better ABT-737 target than Bcl-xL or Bcl-w and only Noxa overcomes resistance v3.0 (CTCAE). Available: http://ctep.cancer.gov/protocolDevelopment/ mediated by Mcl-1, Bfl-1, or Bcl-B. Cell Death Dis 3: e366. electronic_applications/docs/ctcaev3.pdf. Accessed: 2014 Apr 17. 26. Tse C, Shoemaker AR, Adickes J, Anderson MG, Chen J, et al. (2008) ABT-263: 18. Cheson BD, Bennett JM, Kopecky KJ, Buchner T, Willman CL, et al. (2003) a potent and orally bioavailable Bcl-2 family inhibitor. Cancer Res 68: 3421– Revised recommendations of the International Working Group for Diagnosis, Standardization of Response Criteria, Treatment Outcomes, and Reporting 27. Roberts AW, Seymour JF, Brown JR, Wierda WG, Kipps TJ, et al. (2012) Standards for Therapeutic Trials in Acute Myeloid Leukemia. J Clin Oncol 21: Substantial susceptibility of chronic lymphocytic leukemia to BCL2 inhibition: 4642–4649. results of a phase I study of navitoclax in patients with relapsed or refractory 19. Li H, Chen Y, Jones AF, Sanger RH, Collis LP, et al. (2008) Bcl-xL induces disease. J Clin Oncol 30: 488–496. Drp1-dependent synapse formation in cultured hippocampal neurons. Proc Natl 28. Wilson WH, O’Connor OA, Czuczman MS, LaCasce AS, Gerecitano JF, et al. Acad Sci U S A 105: 2169–2174. (2010) Navitoclax, a targeted high-affinity inhibitor of BCL-2, in lymphoid 20. Offen D, Beart PM, Cheung NS, Pascoe CJ, Hochman A, et al. (1998) malignancies: a phase 1 dose-escalation study of safety, pharmacokinetics, Transgenic mice expressing human Bcl-2 in their neurons are resistant to 6- pharmacodynamics, and antitumour activity. Lancet Oncol 11: 1149–1159. hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine neurotox- 29. Vogler M, Hamali HA, Sun XM, Bampton ET, Dinsdale D, et al. (2011) BCL2/ icity. Proc Natl Acad Sci U S A 95: 5789–5794. BCL-X(L) inhibition induces apoptosis, disrupts cellular calcium homeostasis, 21. Paik PK, Rudin CM, Pietanza MC, Brown A, Rizvi NA, et al. (2011) A phase II and prevents platelet activation. Blood 117: 7145–7154. study of obatoclax mesylate, a Bcl-2 antagonist, plus topotecan in relapsed small 30. Brem EA, Thudium K, Khubchandani S, Tsai PC, Olejniczak SH, et al. (2011) cell lung cancer. Lung Cancer 74: 481–485. Distinct cellular and therapeutic effects of obatoclax in rituximab-sensitive and - 22. Dewson G, Kluck RM (2010) Bcl-2 family-regulated apoptosis in health and resistant lymphomas. Br J Haematol 153: 599–611. disease. Cell Health Cytoskel 2: 9–22. 31. Campas C, Cosialls AM, Barragan M, Iglesias-Serret D, Santidrian AF, et al. 23. Thomas M, Gessner A, Vornlocher HP, Hadwiger P, Greil J, et al. (2005) (2006) Bcl-2 inhibitors induce apoptosis in chronic lymphocytic leukemia cells. Targeting MLL-AF4 with short interfering RNAs inhibits clonogenicity and Exp Hematol 34: 1663–1669. engraftment of t(4;11)-positive human leukemic cells. Blood 106: 3559–3566. 32. Rahmani M, Aust MM, Attkisson E, Williams DC, Jr., Ferreira-Gonzalez A, et 24. Izon DJ, Rozenfeld S, Fong ST, Komuves L, Largman C, et al. (1998) Loss of al. (2012) Inhibition of Bcl-2 antiapoptotic members by obatoclax potently function of the homeobox gene Hoxa-9 perturbs early T-cell development and enhances sorafenib-induced apoptosis in human myeloid leukemia cells through induces apoptosis in primitive thymocytes. Blood 92: 383–393. a Bim-dependent process. Blood 119: 6089–6098. PLOS ONE | www.plosone.org 10 October 2014 | Volume 9 | Issue 10 | e108694

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