Navitoclax (ABT-263) Plus Fludarabine/Cyclophosphamide/Rituximab (FCR) or Bendamustine/Rituximab (BR): A Phase 1 Study in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia (CLL),
2011; Elsevier BV; Volume: 118; Issue: 21 Linguagem: Inglês
10.1182/blood.v118.21.3904.3904
ISSN1528-0020
AutoresThomas J. Kipps, Lode J. Swinnen, William G. Wierda, Jeffrey A. Jones, Steven Coutré, Mitchell R. Smith, Jianning Yang, Yue Cui, Todd Busman, Sari H. Enschede, Rod Humerickhouse,
Tópico(s)Advanced Breast Cancer Therapies
ResumoAbstract Abstract 3904 Background: Navitoclax (ABT-263), a novel, orally bioavailable, small molecule, binds with high affinity (Ki ≤1nM) to Bcl-2, Bcl-xL, and Bcl-w, promoting apoptosis. In vitro, navitoclax shows potent targeted cytotoxicity (EC50≤1 μM) against T and B lymphoid malignancies that overexpress Bcl-2. In preclinical models of B-cell lymphoma, navitoclax enhanced efficacy of rituximab (R) when used alone or in combination with chemotherapy. Based on phase 1 trial data, oral navitoclax monotherapy was well-tolerated and had anti-tumor activity in patients (pts) with chronic lymphocytic leukemia (CLL). Thrombocytopenia was the dose-limiting toxicity (DLT). We examined whether navitoclax could be used safely in combination with fludarabine/cyclophosphamide/rituximab (FCR) or bendamustine/rituximab (BR) for treatment of pts with CLL. Methods: This ongoing, phase 1 dose-escalation study is evaluating the safety and pharmacokinetics (PK) of oral navitoclax used in combination with FCR (Arm A) or BR (Arm B) for treatment of pts with relapsed/refractory CLL. Secondary objectives are efficacy endpoints (PFS, ORR, TTP, OS, duration of response). Eligible pts had measurable disease, ECOG performance score ≤1, ANC ≥1000/μL, platelets ≥100,000/mm3, and hemoglobin ≥9.0 g/dL. Preliminary results are reported. Enrolled pts (6 pts/cohort) were assigned to Arm A or Arm B based on physician preference. In both arms, R was 375 mg/m2 on Day 1 of Cycle 1; and 500 mg/m2 on Day 2 of Cycle 2 and on Day 1 of subsequent 28-day cycles. In Arm A, F 25 mg/m2 and C 175 mg/m2 were dosed on Days 2–4 in Cycles 1 and 2, and on Days 1–3 in subsequent cycles. In Arm B, B was dosed at 70 mg/m2 on Days 2 and 3 of Cycles 1 and 2, and on Days 1 and 2 in subsequent cycles. Oral navitoclax was administered once daily (starting dose of 110 mg) pre-chemotherapy on Days 3–5 of Cycle 1 and Days 1–3 of subsequent cycles. Dose escalation decisions were made independently in each arm via a continuous reassessment method, and the objective was to identify a dose of navitoclax in combination with chemotherapy in which <33% of subjects experienced DLTs. Tumor responses were evaluated using NCI-WG 1996 criteria. Adverse events (AE) were graded by NCI CTCAE V3. Pts continued on navitoclax monotherapy up to the recommended phase 2 dose of 250 mg daily for 1 year or until progressive disease or intolerable toxicity. Results: As of July 2011, 28 pts (median age 59 yr [39–80]) have enrolled; 5 in Arm A (FCR+navitoclax; 110 mg) and 23 in Arm B (BR+navitoclax; 110–250 mg). The median number of prior therapies was 2 (range 1–13). In Arm A, 1 pt had a DLT of febrile neutropenia (110 mg). In Arm B, 5 pts had DLT; 1 had elevated ALT and AST (110 mg), 1 had grade 4 febrile neutropenia (200 mg), and 3 had grade 4 thrombocytopenia (250 mg). Overall, the most common (>20%) navitoclax-related AEs of any grade were nausea (73%), fatigue (50%), neutropenia (50%), cough (39%), vomiting (35%), chills (31%), diarrhea (31%), constipation (27%), headache (27%), anemia (23%), and thrombocytopenia (23%). The most common (>19%) grade 3/4 navitoclax-related AE was neutropenia (35%) and thrombocytopenia (19%); but only 2 of the latter pts had hemorrhagic events (Grade 1 epistaxis) unlikely related to navitoclax. Of the 28 pts evaluated for safety, 6 remain active and 22 discontinued (DC); 1 due to AE, 1 due to AE and progressive disease (PD), 3 due to PD, 6 withdrew consent, 3 due to physician discretion, 4 completed therapy, 2 proceeded to transplant, and 2 due to toxicity. Preliminary best anti-tumor responses were assessed in 20 pts. Of the 16 pts assessed in Arm B (BR), 6 achieved complete responses (CR), 7 partial responses (PR), 2 stable disease (SD) and 1 with PD. The ORR was 81% (13/16). In this arm, 3/5 pts with 17p deletion achieved PR. Of the 4 pts assessed in Arm A (FCR), 2 achieved PR, 1 SD and 1 with PD. Preliminary PK results suggest that there is no apparent PK interaction between navitoclax and bendamustine. Conclusions: The combination of navitoclax with BR appears well-tolerated and to have anti-tumor activity. The maximum tolerated dose of navitoclax has been reached at 250 mg for Arm B, but not for Arm A where escalation continues. To date, we have not observed unacceptable myelotoxicity when this bcl-2 antagonist was used in combination with standard cytotoxic chemo-immunotherapy regimens for treatment of pts with CLL. Disclosures: Kipps: Igenica: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Abbott Industries: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; GSK: Research Funding; Gilead Sciences: Consultancy, Research Funding; Amgen: Research Funding. Off Label Use: R05429083 is a novel humanized antibody direct against the standard region of CD44. R05429083 is currently intensive pre-clinical studies and fist dosing of cancer patients has started in Europe in 2011. Swinnen:Abbott Laboratories: Research Funding. Yang:Abbott Laboratories: Employment. Cui:Abbott Laboratories: Employment, Stock Holder at Abbott Laboratories. Busman:Abbott Laboratories: Employment, Owns Abbott Laboratories Stock. Enschede:Abbott Laboratories: Employment, Owns Abbott Laboratories Stock. Humerickhouse:Abbott Laboratories: Employment, Owns Abbott Laboratories Stock.
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