UNFAVORABLE GENETICS IMPACT MRD RESPONSE TO VENETOCLAX+RITUXIMAB RETREATMENT IN RELAPSED OR REFRACTORY CHRONIC LYMPHOCYTIC LEUKEMIA (R/R CLL): PHASE 3 MURANO SUBSTUDY

Utility of measurable residual disease for predicting treatment outcomes with BCR- and BCL2-Targeted therapies in patients with CLL

Inhibitors targeting B-cell receptor (BCR) signaling pathway proteins and B-cell lymphoma-2 (BCL2) in chronic lymphocytic leukemia (CLL) are recommended in the first-line and relapsed/refractory disease settings. Measurable residual disease (MRD) is an important prognostic tool in patients treated with the BCL2-targeted agent, venetoclax. We explored the relationship between MRD status and progression-free (PFS)/overall survival (OS) in patients with CLL, following treatment with novel BCR- and BCL2-targeted agents. Compared with chemoimmunotherapy, higher rates of undetectable (u)MRD were achieved with BCL2-targeted therapies; achieving uMRD status was associated with longer PFS and OS than MRD-positivity. Continuous treatment with BCR-targeted agents did not achieve uMRD status in many patients, and outcomes were not correlated with uMRD status. Future clinical trials of targeted treatment combinations could be designed to demonstrate uMRD as a treatment objective, and allow a response-driven, personalized strategy to optimize treatment and improve OS outcomes.

Clinical experiences with venetoclax and other pro-apoptotic agents in lymphoid malignancies: lessons from monotherapy and chemotherapy combination

BH3-mimetics are a novel drug class of small molecule inhibitors of BCL2 family proteins which restore apoptosis in malignant cells. The only currently approved BH3-mimetic, the selective BCL2 inhibitor venetoclax, is highly efficacious in chronic lymphocytic leukemia and has rapidly advanced to an approved standard of care in frontline and relapsed disease in combination with anti-CD20 monoclonal antibodies. In this context, tumour lysis syndrome and myelosuppression are the most commonly encountered toxicities and are readily manageable with established protocols. Venetoclax is active in other lymphoid malignancies including several B cell non-Hodgkin lymphomas, acute lymphoblastic leukemia and multiple myeloma, with the highest intrinsic sensitivity observed in mantle cell lymphoma and Waldenstrom macroglobulinemia. Venetoclax combination with standard regimens in follicular lymphoma, multiple myeloma and aggressive B cell neoplasms has shown some promise, but further studies are required to optimize dose and scheduling to mitigate increased myelosuppression and infection risk, and to find validated biomarkers of venetoclax sensitivity. Future research will focus on overcoming venetoclax resistance, targeting other BCL2 family members and the rational design of synergistic combinations.