The U.S. FDA approved ofatumumab, an anti-CD20 monoclonal antibody, as maintenance therapy for patients with chronic lymphocytic leukemia (CLL) who have achieved complete or partial response after receiving at least two lines of therapy for recurrent or progressive disease.
The drug’s approval was based on results from the randomized, open-label, phase III PROLONG trial that compared progression-free survival (PFS) in 474 patients treated with ofatumumab (n=238) versus observation (n=236).
Patients had a median age of 64.5 years (range = 33-87 years) and were treated with a median of two prior therapies (range = 2-5). Patients treated with ofatumumab had a median PFS of 29.4 months (95% CI 26.2-34.2), compared with 15.2 months for those in the observation cohort (95% CI 0.38-0.66; p<0.0001), translating to a 50 percent reduction in the risk of disease progression (hazard ratio [HR] = 0.50; p<0.0001). Additionally, the time to next therapy was 6.9 months longer with ofatumumab compared with observation.
The most common treatment-related adverse events (AEs) included infusion reactions, neutropenia, and upper respiratory tract infection. The most common grade 3/4 AEs for ofatumumab versus observation were neutropenia (22% vs. 8%) and pneumonia (5% vs. 3%). One-third of patients reported serious AEs, including pneumonia, pyrexia, and neutropenia. Eight percent of patients in the ofatumumab arm experienced an AE that resulted in treatment discontinuation.
Ofatumumab was approved by the FDA in October 2009 to treat previously untreated patients with CLL for who are refractory to fludarabine and alemtuzumab; in April 2014, this indication was expanded to include previously untreated patients with CLL who were ineligible for fludarabine-based therapy.
Source: U.S. FDA press release, January 19, 2016.