A Single-Center Retrospective Cohort Analysis of Venetoclax in Relapsed/Refractory Multiple Myeloma

Background

Despite recent advances, treatment of relapsed refractory multiple myeloma (RRMM) remains a challenge. Venetoclax, a BH3 mimetic, is an oral, specific, and potent small molecule inhibitor of BCL-2 that has been approved for treatment of 17p-deleted CLL and in combination with azacitidine or decitabine in AML patients >/= 75 years of age.Pre-clinical and clinical studies suggest that bcl-2 inhibition can induce MM cell death and may synergize with bortezomib and dexamethasone. Based on this, several prospective clinical trials of venetoclax in RRMM have been performed. However, clinical use of this targeted therapeutic for salvage therapy in RRMM has not been well described.

Methods

We performed a single-center, retrospective chart review of all patients with RRMM diagnosed after January 1, 2009 who were treated with off-label use of venetoclax. The goal of this study was to describe the clinical characteristics of these patients, assess the response to salvage treatment with venetoclax as determined by the International Myeloma Working Group (IMWG) criteria, and assess the toxicities during salvage treatment with venetoclax in an academic practice setting.

Results

43 patients were identified. Median number of lines of prior therapy was 7 (range 2-13). 12 patients had documented high risk cytogenetics, defined as the presence of a 17p deletion, t(14;16), t(14;20), t(4,14), gain (1q), or nonhyperdiploidy. Of the 36 patients with cytogenetics/FISH available, 8 had t(11;14). 34 patients were refractory to bortezomib. 40 patients had progressed after carfilzomib, 36 after pomalidomide, and 41 after anti-CD38 antibody therapy. 39 patients were treated with venetoclax in combination with a proteasome inhibitor (bortezomib (n=36); carfilzomib (n=3)). 23 patients were treated with venetoclax, proteasome inhibitor, and dexamethasone. Patients were started at 400 mg daily for 7 days then increased to the median dose of 800mg daily (11 received < 800mg/daily as a final dose and one received >800 mg/daily as final dose). Overall patients were on treatment for a median of 67 days (range 2-855). 2 patients received intermittent venetoclax therapy, defined as being off venetoclax for at least 3 months before restarting. Best response by IMWG criteria include; CR 5%( 2/43), VGPR 12% (5/43) and PR 16% (7/43) for an overall response rate of 33% (14/43). In addition, MR was seen in 5% (2/43) and stable disease in 9% (4/43). Fifty-one percent (22/43) had progressive disease (PD). Out of the 8 patients who had t(11;14), best responses were: 2 VGPR, 2 PR, 1 SD, and 3 PD for a response rate of 50% (4/8) in this subgroup. Median time to best response for all responding patients was 90 days (range 15-305) and median duration of response was 206 days (range 28-820). At time of data collection, median follow-up time from venetoclax treatment initiation was 192 days (range 8-1058). Four patients have not progressed and remain on therapy, 23 patients remain alive, and 4 patients have been lost to follow-up for over 6 months. The most common treatment related AEs were cytopenias including leukopenia in 26 /43 (60%) patients, neutropenia in 19/43 (44%) patients, and thrombocytopenia in 22/43 (51%) patients. Non-hematologic toxicities included diarrhea in 12/43 (30%) patients, nausea/vomiting in 15/43 (35%) patients, infections in 11/43 (26%) patients, and fatigue in 23/43 (53%) patients. 8/43 (19%) patients required dose reduction, 7/43 (16%) patients required temporary discontinuation of treatment, and 4/43 (9%) patients required permanent discontinuation due to treatment related AEs. 38/43 (88%) patients had any grade treatment related AEs, 27/43 (63%) patients had grade >/= 3 AEs and 2/43 (5%) patients had treatment related SAEs. One patient had a treatment related death from an infectious complication (CMV pneumonitis).

Conclusions

Venetoclax is an active and well-tolerated agent in relapsed multiple myeloma. Furthermore, it is easily administered in the outpatient setting. Additional areas of research with this therapy include understanding the importance of t(11:14) for response and selecting the best anti-MM partner for combination therapy.