Randomized Trial in Unfit, Elderly Chronic Lymphocytic Leukemia (CLL) Patients with Comorbidities of Dose-Reduced Oral Fludarabine and Cyclophosphamide Plus Obinutuzumab (FC+G) Versus Chlorambucil Plus Obinutuzumab (Cbl+G) As Front-Line Therapy

Abstract

BACKGROUNDThe prior Australasian Leukaemia and Lymphoma Group (ALLG) CLL5 Study showed dose-reduced oral fludarabine and cyclophosphamide plus rituximab (FCR3) was safe, tolerable and effective in fit elderly patients for front-line therapy for CLL. The German CLL11 Study showed chlorambucil plus obinutuzumab (Cbl+G) was superior to chlorambucil alone or with rituximab in unfit patients requiring initial therapy. We conducted a randomized study to assess the safety, tolerability, and efficacy of dose-reduced FC + obinutuzumab (G) (FC+G) versus Cbl+G in unfit (i.e. with comorbidity), elderly patients with CLL.METHODSPatients aged ≥65 years and considered “unfit” defined by co-morbidities using the Cumulative Illness Rating Scale [CIRS] ≥6 were eligible for the ALLG CLL7 study. Patients with any single organ system score ≥4 were excluded. Previously untreated patients with progressive CLL aged ≥65 and CIRS ≥6 were randomised to one of 2 therapy arms: (i) Chlorambucil 0.5mg/kg D1+15 p.o. + obinutuzumab (“G”) (i.v. 1000mg/m2 cycle 1, Day 1, 8, 15, and 1000mg/m2 D1 cycles 2-6), or (ii) FC(rd)+G: F-24mg/m2 p.o. and C-150mg/m2 p.o. D1-3 + G (same schedule above) at 4 weekly intervals for planned 6 cycles. Early stopping for toxicity was mandated: treatment could be delayed for 2 weeks for grade 3+ toxicity, but if unresolved by 2 weeks, patients were taken off study. The primary end-point was grade 3+ non-hematological, and grade 4 hematological adverse events. Secondary objectives were overall response rate (ORR), complete remission (CR), partial remission (PR), progression-free survival (PFS) and overall survival (OS) and minimal residual disease (MRD) negativity. Final staging was performed between 2-3 months following final treatment cycle.RESULTSPatient characteristics Patient recruitment was terminated early due to poor recruitment. At the time of study closure, there were 32 patients, with 15 on Cbl+G and 17 on FC(rd)+G. The mean age was 74.2 years (range 66-85 years) with 23 females (71.9%) and 9 males (28.1%). The CIRS score was 6 in 4 patients (12.5%), 6-8 in 14 (43.8%), 8-10 in 11 (34.4%) and >10 in 3 (9.4%). Binet stage at registration was stage A 18.2%, B 27.3% and C 54.5%.Tolerability Both therapies were tolerable with 15/17 (88.2%) completing all 6 cycles of FC(rd)+G and 12/15 (92.3%) completing six cycles of Cbl+G.Toxicity Most toxicity was hematological and manageable. Grade 3/4 hematological toxicity was more common with FC(rd)+G than Cbl+G occurring in 60% with FC(rd)+G and 38.5% with Cbl+G (Table 1). There was one death due to progressive CLL on the FC(rd)+G arm.Response rate A complete remission (CR), confirmed by bone marrow (BM) trephine, was achieved in 86.6% of patients on FC(rd)+G versus (vs) 53.9% on Cbl+G, partial response (PR/nPR) in 1 (6.7%) on FC(rd)+G, and 6 (46.2%) on Cbl+G, and either stable or progressive disease (SD or PD) on 1 on FC(rd)+G, and nil on Cbl+G. BM MRD-negativity rates were 3/17 (20.0%) FC(rd)+G vs 1/15 (7.7%) Cbl+G (Table 2).CONCLUSIONThis randomized trial of dose-reduced FC(rd)+G vs Cbl+G in elderly patients aged ≥65 and with co-morbidities (CIRS ≥6) was terminated early due to poor recruitment. Due to the dose-reduced FC, and early stopping rule, treatment was safe and tolerable and most patients completed all 6 cycles of planned therapy. Grade 3/4 toxicity was mainly hematological and manageable, with higher rates of neutropenia with the FC (60%) vs Cbl (35.7%) backbone. FC(rd)+G compared to Cbl+G resulted a higher CR rate of 86.6%% versus 53.9%, and higher MRD-negativity (20% vs 7.7%). Progression-free and overall survival are being evaluated. [Display omitted] DisclosuresBadoux:Roche: Research Funding. Cull:Takeda Australia: Other: Travel Expenses; Amgen Australia: Other: Travel Expenses; AbbVie (Australia): Membership on an entity's Board of Directors or advisory committees. Tam:Janssen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BeiGene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.