A fixed-duration, measurable residual disease–guided approach in CLL: follow-up data from the phase 2 ICLL-07 FILO trial

Abstract

Trials assessing first-line, fixed-duration approaches in chronic lymphocytic leukemia (CLL) are yielding promising activity, but few long-term data are available. We report follow-up data from a phase 2 trial (ICLL-07 FILO; NCT02666898) in previously untreated, medically-fit patients (N=135). Patients underwent obinutuzumab-ibrutinib induction for 9 months; then, following evaluation (N=130 evaluable), those in complete remission and with bone marrow measurable residual disease (BM MRD) <0.01% (n=10) received ibrutinib for 6 additional months, while those in partial remission and/or with BM MRD ≥0.01% - the majority (n=120) - also received 4 cycles of immunochemotherapy (fludarabine/cyclophosphamide-obinutuzumab). Beyond end of treatment, responses were assessed 3 monthly and peripheral blood MRD 6 monthly. At median follow-up 36.7 months from treatment start, progression-free and overall survival rates (95% confidence interval) at 3 years were 95.7% (92.0 to 99.5) and 98% (95.1 to 100), respectively. Peripheral blood MRD <0.01% rates were 97%, 96%, 90%, 84%, and 89% at months 16, 22, 28, 34, and 40, respectively. No new treatment-related or serious adverse event occurred beyond end of treatment. Thus, in previously untreated, medically-fit patients with CLL, a fixed-duration (15 months), MRD-guided approach achieved high survival rates, a persistent MRD benefit beyond the end of treatment, and low long-term toxicity.