A Multicenter Analysis of the Outcomes with Venetoclax in Patients with Relapsed Mantle Cell Lymphoma.

To report the activity of venetoclax in patients with relapsed mantle cell lymphoma (MCL), we identified 81 patients treated with venetoclax monotherapy (n=50, 62%) or in combination with a BTK inhibitor (n=16, 20%), an anti-CD20 monoclonal antibody (n=11, 14%), or others at 12 US academic medical centers. Patients had high-risk disease features including Ki67 >30% (61%), blastoid/pleomorphic histology (29%), complex karyotype (34%), and TP53 alterations (49%), and received a median of 3 prior treatments including BTK inhibitors in 91%. Venetoclax alone or in combination resulted in an overall response rate (ORR) of 40% and median progression-free (PFS) and overall survival (OS) of 3.7 and 12.5 months, respectively. The receipt of ≤ 3 prior treatments was associated with higher odds of response to venetoclax in a univariable analysis. In a multivariable analysis, having a high-risk MIPI score prior to venetoclax and disease relapse or progression within 24 months of diagnosis were associated with inferior OS whereas the use of venetoclax in combination was associated with superior OS. Although most patients (61%) had low risk for tumor lysis syndrome (TLS), 12.3% of patients developed TLS despite the implementation of several mitigation strategies. In conclusion, venetoclax resulted in good ORR but short PFS in high-risk patients with MCL and may have a better role in earlier lines of treatment and/or in combination with other active agents. TLS remains an important risk in patients with MCL who initiate treatment with venetoclax.