A Multicenter, Phase IV Observational Study Of Ofatumumab In Chronic Lymphocytic Leukemia (CLL): A European Research Initiative On CLL (ERIC) Study

Ofatumumab was given a conditional approval in the EU on April 2010 for the treatment of CLL refractory to fludarabine (F-ref) and alemtuzumab (A-ref), encouraging the retrieval of further data in patients treated in a “daily life” setting and to investigate treatment safety.

The main objective of this study was to obtain information on the safety profile of ofatumumab given outside clinical trials in patients with previously treated CLL. The secondary endpoints were efficacy, progression-free-survival (PFS), and overall survival (OS).

This was an observational, retrospective study. Patients were eligible regardless of prior treatments or disease status and provided they had not been included in ofatumumab clinical trials. Data on patients’ characteristics at diagnosis, prior treatment, adverse events response rate, PFS and OS were recorded.

One-hundred and twenty patients were screened of which 103 from 25 centers in 10 European countries were eventually eligible for the study. There were 71 males; median age at initiation of ofatumumab was 64 years (range, 38-84); 66% patients were in advanced clinical stage (Rai III-IV/Binet C) and 33 patients presented bulky lymphadenopathy. Number of prior lines of therapy was 4 (range, 1-13). 94% had received prior F-based therapy, 54% received A-based therapy and 51% received both. Eighty-one percent had been previously exposed to rituximab-combination regimens. Fifty-four percent were F-ref, 70% A-ref and 41% were both F- and A-refractory. Cytogenetics within 3 months prior therapy was available in 52 patients of which 34 presented abnormalities (11 patients: 17p-; 9 patients: 11q-; 2 patients: 13q-; 1 patient: trisomy 12; 11 patients: two or more abnormalities including 17p- or 11q-). Forty-two of 50 patients showed unmutated IGHV genes. The median number of cycles of ofatumumab given was 9 (range, 0-16) and the median percentage of given/planned cycles was 83.3% (range, 0-133). In most patients the treatment dose and schedule were as follows: 300 mg 1^st infusion followed by 2000 mg for subsequent infusions (8 weekly followed by 4 doses monthly). One hundred and sixty-one adverse events were reported in 68 patients, with 28 (17%) of them being considered as ofatumumab-related. Infusion related-reactions occurred in 19 (28%) patients (III-IV: 6%). Neutropenia was reported in 26% (III-IV: 19%), thrombocytopenia in 15% (III-IV: 12%) and anemia in 15% (III-IV: 7%). The non-hematological adverse events, included infection 44% (III-IV: 36%), fatigue 10% (III-IV: 4%), fever 10% (III-IV: 6%), rash 10% (III-IV: 3%), cough 7% (III-IV: 1%), diarrhea 6% (grade III-IV: 0%) and nausea 1% (III-IV: 0%). Hematologic toxicity correlated with the number of prior lines of therapy. Autoimmune hemolytic anemia and Richter syndrome were reported in one patient each. Two heavily pre-treated patients (5 and 6 prior lines of therapy, respectively) developed progressive multifocal leukoencephalopathy. The overall response rate (ORR) was 23% and the median PFS and OS were 5 and 12 months, respectively. The main causes of death were disease progression (61%) and infection (28%).

The safety profile of ofatumumab given outside clinical trials to patients with poor-prognosis and heavily pre-treated CLL was consistent with that observed in clinical trials. Although not unexpectedly the ORR was lower in this study, PFS and OS were in line with those reported in phase II trials.

Montillo:Roche: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; GSK: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Bloor:GSK: Consultancy, Honoraria, Paid speaker Other. Schuh:GSK: Honoraria; Celgene: Honoraria; Mundipharma: Honoraria. Geisler:Roche: Consultancy; GSK: Consultancy. Hillmen:GlaxoSmithKline: Honoraria, Research Funding. Stilgenbauer:GSK: Honoraria, support Other. Smolej:GSK: Consultancy, Honoraria, travel grants Other. Jaeger:GSK: Honoraria, Research Funding. Leblond:Roche : Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Mundipharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau. Kimby:Roche: Consultancy, Honoraria, Research Funding; celgene: Consultancy, Honoraria, Research Funding; Teva: Consultancy, Honoraria, Research Funding; Emergent BioSolutions: Consultancy, Honoraria, Research Funding; Gilead Sciences: Consultancy, Honoraria, Research Funding; Jansen: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding.