Chlorambucil PLUS Rituximab As FRONT-LINE Therapy for Elderly and/or Unfit CLL Patients. LONG-TERM Follow-up and Correlation with Biologic-Based Risk Stratification
Authors: Laurenti Luca , Innocenti Idanna , Autore Francesco , Pasquale Raffaella , Vannata Barbara , Ciolli Stefania , Mauro Francesca Romana , Mannina Donato , Del Poeta Giovanni , D'Arena Giovanni , Massaia Massimo , Coscia Marta , Molica Stefano , Pozzato Gabriele , Efremov Dimitar G , Marasca Roberto , Galieni Piero , Cuneo Antonio , Orlando Sonia , Piciocchi Alfonso , Boncompagni Riccardo , Vincelli Donatella Iolanda , Liberati Anna Marina , Russo Filomena , Foa Robin 
Published: October 2019

Abstract

Introduction. Elderly patients with chronic lymphocytic leukemia (CLL) and younger patients with comorbidities are often treated with chlorambucil (Chl), despite the relatively low response rates. The addition of anti-CD20 monoclonal antibodies to Chl substantially increases the response rates, without negatively affecting tolerability. Overall response rates (ORR) between 66% to 84% have been reported with these combinations, with complete responses (CR)ranging from 8% to 26%.
Methods. We conducted a retrospective analysis on the use of the Chl-rituximab (R) combination as frontline treatment for elderly (≥65 years) and/or unfit (CIRS >6) CLL patients treated at 15 different Italian hematologic centers. The main aim of the study was to further establish the safety and efficacy of the Chl-R protocol and investigate whether certain CLL patients for whom this protocol could be particularly effective could be identified. To this end, we performed a subgroup analysis stratifying patients according to FISH and IGHV results: high risk group (HR) included patients with 17p deletion, intermediate risk group (IR) patients with 11q deletion and/or unmutated IGHV, low risk group (LR) patients without 11q or 17p deletion and/or unmutated IGHV.
Results. One hundred and two patients who underwent treatment between 2009 and 2011 were enrolled in the study. Patients' clinical and biologic characteristics are summarized in Table 1. Three patients discontinued treatment earlier than planned: 1 for an episode of autoimmune hemolytic anemia (AIHA) that developed after the 2nd cycle of Chl and before starting R treatment and 2 patients for disease progression after the 3rd and 5th cycle of Chl-R, respectively. The median number of Chl and R cycles administered in the 102 patients was 8 (range 2-12) and 6 (range 1-9), respectively. The planned treatment schedule was different among centers: the two main schedules used were Chl administered at 1 mg/kg for each cycle every 28 days, given at a fixed daily dose of 10 mg starting from day 1 and repeated for 8 cycles, and Chl administered at 8 mg/m2/day for seven days of each of eight 28-day-cycles. R was added to Chl from the 3rd cycle onwards and was administered on day 1 of each cycle at a dose of 375 mg/m2 during the first administration and 500 mg/m2 for the subsequent 5 cycles.
On an intention to treat basis, the ORR was 87.1%. Thirty-two patients (31.7%) obtained a CR and 56 patients (55.4%) obtained a partial response (PR). Nostatistically significant differences were noted in terms of ORR for age above or below 70 years, fitness status, ECOG, bulky disease, cytogenetic risk abnormalities, IGHV mutational status, ZAP-70 or CD38 expression.Median progression-free survival (PFS) and time to retreatment (TTR) were reached at 43.7 and 72.3 months, respectively. Median overall survival (OS) was not reached; 86.1% and 81.2% of patients were alive at 48 and 60 months, respectively. The most frequent serious adverse event was grade 3-4 neutropenia, occurring in 13.7% of patients. Grade 3-4 extra-hematologic side effects were uncommon (9.8%).
Subgroup analysis of the LR and IR patients (no HR patients were enrolled) showed that LR patients had a significantly better PFS than IR patients (65.8 months vs 35.2 months, p=0.001; Fig. 1),with 54.9% of patients remaining free from progression 60 months after treatment.
Conclusions. Treatment of elderly and/or unfit CLL patients with the Chl-R regimen is associated with low toxicity, a high ORR and durable PFS. Particularly good results are achieved in CLL patients with a mutated IGHV profile and not carrying both 17p and 11q deletion, suggesting that in this low-risk subset of unfit patients Chl-R could represent the optimal therapeutic option, in consideration of safety, efficacy and costs.

Disclosures
D'Arena: Janssen-Cilag: Honoraria. Coscia:Gilead: Honoraria; ROCHE: Honoraria, Other: Advisory board; Janssen: Honoraria; Mundipharma: Honoraria; Karyopharm: Research Funding. Molica:Jansen: Membership on an entity's Board of Directors or advisory committees; Roche Italy: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Speakers Bureau. Efremov:Gilead: Honoraria.