Selective targeting of BCL2 with venetoclax had a manageable safety profile and induced substantial responses in patients with relapsed CLL or SLL, including those with poor prognostic features. (Funded by AbbVie and Genentech; ClinicalTrials.gov number, NCT01328626.).

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Purpose B-cell leukemia/lymphoma-2 (BCL-2) overexpression is common in many non-Hodgkin lymphoma (NHL) subtypes. A phase I trial in patients with NHL was conducted to determine safety, pharmacokinetics, and efficacy of venetoclax, a selective, potent, orally bioavailable BCL-2 inhibitor. Patients and Methods A total of 106 patients with relapsed or refractory NHL received venetoclax once daily until progressive disease or unacceptable toxicity at target doses from 200 to 1,200 mg in dose-escalation and safety expansion cohorts. Treatment commenced with a 3-week dose ramp-up period for most patients in dose-escalation cohorts and for all patients in safety expansion. Results NHL subtypes included mantle cell lymphoma (MCL; n = 28), follicular lymphoma (FL; n = 29), diffuse large B-cell lymphoma (DLBCL; n = 34), DLBCL arising from chronic lymphocytic leukemia (Richter transformation; n = 7), Waldenström macroglobulinemia (n = 4), and marginal zone lymphoma (n = 3). Venetoclax was generally well tolerated. Clinical tumor lysis syndrome was not observed, whereas laboratory tumor lysis syndrome was documented in three patients. Treatment-emergent adverse events were reported in 103 patients (97%), a majority of which were grade 1 to 2 in severity. Grade 3 to 4 events were reported in 59 patients (56%), and the most common were hematologic, including anemia (15%), neutropenia (11%), and thrombocytopenia (9%). Overall response rate was 44% (MCL, 75%; FL, 38%; DLBCL, 18%). Estimated median progression-free survival was 6 months (MCL, 14 months; FL, 11 months; DLBCL, 1 month). Conclusion Selective targeting of BCL-2 with venetoclax was well tolerated, and single-agent activity varied among NHL subtypes. We determined 1,200 mg to be the recommended single-agent dose for future studies in FL and DLBCL, with 800 mg being sufficient to consistently achieve durable response in MCL. Additional investigations including combination therapy to augment response rates and durability are ongoing.

Summary Background Selective BCL2 inhibition with venetoclax has substantial activity in patients with relapsed or refractory chronic lymphocytic leukaemia. Combination therapy with rituximab enhanced activity in preclinical models. The aim of this study was to assess the safety, pharmacokinetics, and activity of venetoclax in combination with rituximab. Methods Adult patients with relapsed or refractory chronic lymphocytic leukaemia (according to the 2008 Modified International Workshop on CLL guidelines) or small lymphocytic lymphoma were eligible for this phase 1b, dose-escalation trial. The primary outcomes were to assess the safety profile, to determine the maximum tolerated dose, and to establish the recommended phase 2 dose of venetoclax when given in combination with rituximab. Secondary outcomes were to assess the pharmacokinetic profile and analyse efficacy, including overall response, duration of response, and time to tumour progression. Minimal residual disease was a protocol-specified exploratory objective. Central review of the endpoints was not done. Venetoclax was dosed daily using a stepwise escalation to target doses (200–600 mg) and then monthly rituximab commenced (375 mg/m2 in month 1 and 500 mg/m2 in months 2–6). Adverse events were graded according to the National Cancer Institute Common Terminology Criteria for adverse events version 4.0. Protocol-guided drug cessation was allowed for patients who achieved complete response (including complete response with incomplete marrow recovery) or negative bone marrow minimal residual disease. Analyses were done per protocol for all patients who commenced drug and included all patients who received at least one dose of venetoclax. Data were pooled across dose cohorts. Patients are still receiving therapy and follow-up is ongoing. The trial is registered at ClinicalTrials.gov, number NCT01682616. Findings Between Aug 6, 2012, and May 28, 2014, we enrolled 49 patients. Common grade 1–2 toxicities included upper respiratory tract infections (in 28 [57%] of 49 patients), diarrhoea (27 [55%]), and nausea (25 [51%]). Grade 3–4 adverse events occurred in 37 (76%) of 49 patients; most common were neutropenia (26 [53%]), thrombocytopenia (eight [16%]), anaemia (seven [14%]), febrile neutropenia (six [12%]), and leucopenia (six [12%]). The most common serious adverse events were pyrexia (six [12%]), febrile neutropenia (five [10%]), lower respiratory tract infection, and pneumonia (each three [6%]). Clinical tumour lysis syndrome occurred in two patients (resulting in one death) who initiated venetoclax at 50 mg. After enhancing tumour lysis syndrome prophylaxis measures and commencing venetoclax at 20 mg, clinical tumour lysis syndrome did not occur. The maximum tolerated dose was not identified; the recommended phase 2 dose of venetoclax in combination with rituximab was 400 mg. Overall, 42 (86%) of 49 patients achieved a response, including a complete response in 25 (51%) of 49 patients. 2 year estimates for progression-free survival and ongoing resp...

Purpose Venetoclax is an orally bioavailable B-cell lymphoma 2 inhibitor. US Food and Drug Administration and European Medicines Agency approval for patients with 17p deleted relapsed/refractory chronic lymphocytic leukemia [del(17p) CLL] was based on results from 107 patients. An additional 51 patients were enrolled in a safety expansion cohort. Extended analysis of all enrolled patients, including the effect of minimal residual disease (MRD) negativity on outcome, is now reported. Patients and Methods Overall, 158 patients with relapsed/refractory or previously untreated (n = 5) del(17p) CLL received venetoclax 400 mg per day after an initial dose ramp up. Responses were based on 2008 International Workshop on Chronic Lymphocytic Leukemia criteria, with monthly physical exams and blood counts. Computed tomography scan was mandatory at week 36, after which assessment made was by clinical evaluation. Marrow biopsy was performed when complete remission was suspected. MRD was assessed by flow cytometry. Results Patients had a median of two prior therapies (range, zero to 10 therapies), 71% had TP53 mutation, and 48% had nodes that were ≥ 5 cm. Median time on venetoclax was 23.1 months (range, 0 to 44.2 months) and median time on study was 26.6 months (range, 0 to 44.2 months). For all patients, investigator-assessed objective response rate was 77% (122 of 158 patients; 20% complete remission) and estimated progression-free survival at 24 months was 54% (95% CI, 45% to 62%). For 16 patients who received prior kinase inhibitors, objective response rate was 63% (10 of 16 patients) and 24-month progression-free survival estimate was 50% (95% CI, 25% to 71%). By intent-to-treat analysis, 48 (30%) of 158 patients achieved MRD below the cutoff of 10 in blood. Common grade 3 and 4 adverse events were hematologic and managed with supportive care and/or dose adjustments. Conclusion Venetoclax achieves durable responses and was well tolerated in patients with del(17p) CLL. A high rate of blood MRD < 10 was achieved in this high-risk population.