• Arnon P Kater, John F Seymour, Peter Hillmen, Barbara Eichhorst, Anton W Langerak, Carolyn Owen, Maria Verdugo, Jenny Wu, Elizabeth A Punnoose, Yanwen Jiang, Jue Wang, Michelle Boyer, Kathryn Humphrey, Mehrdad Mobasher, and Thomas J Kipps.
• 1 Amsterdam Universitair Medische Centra, University of Amsterdam, Amsterdam, the Netherlands.
• J. Clin. Oncol. 2019 Feb 1; 37 (4): 269-277.

PurposeThe MURANO study demonstrated significant progression-free survival (PFS) benefit for fixed-duration venetoclax-rituximab compared with bendamustine-rituximab in relapsed/refractory chronic lymphocytic leukemia. With all patients off treatment, we report minimal residual disease (MRD) kinetics and updated outcomes.MethodsPatients were randomly assigned to 2 years of venetoclax plus rituximab during the first six cycles, or six cycles of bendamustine-rituximab. Primary end point was PFS. Safety and peripheral blood (PB) MRD status-at cycle 4, 2 to 3 months after end of combination therapy (EOCT), and every 3 to 6 months thereafter-were secondary end points.ResultsOf 194 patients, 174 (90%) completed the venetoclax-rituximab phase and 130 (67%) completed 2 years of venetoclax. With a median follow-up of 36 months, PFS and overall survival remain superior to bendamustine-rituximab (hazard ratio, 0.16 [95% CI, 0.12 to 0.23]; and hazard ratio, 0.50 [95% CI, 0.30 to 0.85], respectively). Patients who received venetoclax-rituximab achieved a higher rate of PB undetectable MRD (uMRD; less than 10-4) at EOCT (62% v 13%) with superiority sustained through month 24 (end of therapy). Overall, uMRD status at EOCT predicted longer PFS. Among those with detectable MRD, low-level MRD (10-4 to less than 10-2) predicted improved PFS compared with high-level MRD (10-2 or greater). At a median of 9.9 months (range, 1.4 to 22.5 months) after completing fixed-duration venetoclax-rituximab, overall only 12% (16 of 130) of patients developed disease progression (11 high-level MRD, three low-level MRD). At the end of therapy, 70% and 98% of patients with uMRD remained in uMRD and without disease progression, respectively.ConclusionWith all patients having finished treatment, continued benefit was observed for venetoclax-rituximab compared with bendamustine-rituximab. uMRD rates were durable and predicted longer PFS, which establishes the impact of PB MRD on the benefit of fixed-duration, venetoclax-containing treatment. Low conversion to detectable MRD and sustained PFS after completion of 2 years of venetoclax-rituximab demonstrate the feasibility of this regimen.

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