Chlorambucil plus rituximab with or without maintenance rituximab as first-line treatment for elderly chronic lymphocytic leukemia patients

In a phase II trial, we evaluated chlorambucil and rituximab (CLB-R) as first-line induction treatment with or without R as maintenance for elderly chronic lymphocytic leukemia (CLL) patients. Treatment consisted of eight 28-day cycles of CLB (8 mg/m²/day, days 1-7) and R (day 1 of cycle 3, 375 mg/m²; cycles 4-8, 500 mg/m²). Responders were randomized to 12 8-week doses of R (375 mg/m²) or observation. As per intention-to-treat analysis, 82.4% (95% CI, 74.25-90.46%) of 85 patients achieved an overall response (OR), 16.5% a complete response (CR), 2.4% a CR with incomplete bone marrow recovery. The OR was similar across Binet stages (A 86.4%, B 81.6%, and C 78.6%) and age categories (60-64 years, 92.3%; 65-69, 85.2%; 70-74, 75.0%; ≥75, 81.0%). CLB-R was well tolerated. After a median follow-up of 34.2 months, the median progression-free survival (PFS) was 34.7 months (95% CI, 33.1-39.5). TP53 abnormalities, complex karyotype, and low CD20 gene expression predicted lack of response; SF3B1 mutation and BIRC3 disruption low CR rates. IGHV mutations significantly predicted PFS. R maintenance tended towards a better PFS than observation and was safe and most beneficial for patients in partial response and for unmutated IGHV cases. CLB-R represents a promising option for elderly CLL patients.