Low-Dose FCR Is a Safe and Effective Treatment Option for Elderly/Comorbid Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma. Updated Results of Project Q-Lite By Czech CLL Study Group

Background: Combination of fludarabine, cyclophosphamide and rituximab (FCR) is the current gold standard for physically fit patients (pts) with chronic lymphocytic leukemia (CLL). Nevertheless, many CLL patients cannot tolerate this intensive regimen owing to advanced age and/or serious comorbidities. Combination protocols based on dose-reduced fludarabine demonstrated promising results in pilot studies. Therefore, the Czech CLL Study Group initiated Project Q-lite, an observational study to assess efficacy and safety of low-dose FCR regimen used in elderly/comorbid patients with CLL/SLL. Updated results including progression-free survival (PFS), overall survival (OS) and multivariate analysis are presented. Patients and Methods: Between March 2009 and July 2012, a total of 207 pts with active disease (CLL, n=196, SLL, n=11) were treated by low-dose FCR at 16 centers cooperating within Czech CLL Study Group. Dose reductions of chemotherapy compared to full-dose FCR were: 50% of fludarabine (12 mg/m² i.v. or 20 mg/m² orally on days 1-3) and 60% of cyclophosphamide (150 mg/m² i.v./p.o. on days 1-3). Rituximab was administered in standard schedule (375mg/m² i.v. day 1 in 1st cycle, 500mg/m² i.v. day 1 from 2nd cycle). Treatment was repeated every 4 weeks; antimicrobial prophylaxis with sulfamethoxazol/trimethoprim and aciclovir or equivalents was recommended. The basic characteristics are summarized in Table 1. Results: Based on intention-to-treat principle, the overall response rate / complete responses including clinical CR (without bone marrow biopsy) and CRi were 81/37% in 1st line and 63/30% in relapsed/refractory (R/R) disease. Serious (CTCAE grade III/IV) neutropenia was frequent (56 and 50%) but grade III/IV infections were only 15 and 18%. The most common causes of death were CLL progression and infections. At the median follow-up of 25 months, median progression-free survival (PFS) for previously untreated and R/R patients was 28 and 15 months; median overall survival (OS) has not been reached in previously untreated pts (75 % at 30 months) and was 30 months in R/R pts. Multivariate analysis identified del 11q, del 17p, bulky lymphadenopathy (1st line) and del 17p (R/R) as independent predictors of shorter PFS; absence of therapeutic response was the only factor associated with shorter OS (both in 1st line and R/R pts). Conclusions: Low-dose FCR appears to be an effective treatment for elderly/comorbid patients with CLL/SLL in first-line as well as R/R setting. Toxicity was acceptable and manageable. In historical comparison, efficacy of low-dose FCR compares favourably with chlorambucil monotherapy and is similar to obinutuzumab-chlorambucil combination from German CLL11 study. Interestingly, neither CIRS score nor creatinine clearance were predictive of PFS/OS. The study is registered at www.clinicaltrials.gov (NCT02156726).

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