Arzerra

Drug Overview
Arzerra (ofatumumab; Genmab/Novartis) is a fully human immunoglobulin G1 and high-affinity antibody that targets a novel epitope on cluster of differentiation 20 (CD20) on the B-cell membrane. Arzerra binds effectively to both the small and large extracellular loops on CD20 and releases very slowly over time. Preclinical and clinical data have demonstrated Arzerra’s ability to deplete B cells effectively.
Arzerra is approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of chronic lymphocytic leukemia (CLL) patients who have relapsed or are refractory to fludarabine and Campath (alemtuzumab; Genzyme) therapy, as well as for previously untreated patients for whom fludarabine-based therapy is considered inappropriate due to advanced age and co-morbidities. Arzerra’s modest uptake has been due to its direct competition with Rituxan (rituximab; Biogen/Roche) in the first-line setting, an inability to identify Arzerra non-responders, and the drug’s high cost. The decision to not compare the first-line Arzerra plus chlorambucil combination to Rituxan in the Phase III COMPLEMENT trial reduced the drug’s ability to be competitive in the market. In addition, Genmab did not compare Arzerra to Rituxan in the Phase III COMPLEMENT 2 trial for relapsed CLL. Arzerra’s modest market share will likely begin to erode as newer monoclonal antibodies and small molecule inhibitors gain uptake in both treatment-naïve and relapsed/refractory CLL.

Analyst Outlook
Novartis is positioning Arzerra (ofatumumab) primarily for the second-line treatment of patients refractory to Rituxan (rituximab; Roche/Biogen/Chugai/Zenyaku Kogyo) therapy. However, top-line Phase III results indicated that the overall response rate to Arzerra in cases refractory to Rituxan was below expectations (ClinicalTrials.gov identifier: NCT00394836). In addition, the Phase III HOMER study comparing Arzerra to Rituxan in patients with Rituxan-refractory disease was suspended after an interim analysis showed it was unlikely that Arzerra would demonstrate superiority if the trial was completed (ClinicalTrials.gov identifier: NCT01200589). Arzerra is currently in an ongoing Phase III COMPLEMENT A+B trial that is assessing the efficacy of Arzerra combined with Treanda (bendamustine; Teva) as a second-line therapy in patients who did not respond to a Rituxan-based regimen (ClinicalTrials.gov identifier: NCT01077518). While it is unlikely that Arzerra’s development as a monotherapy will continue for follicular lymphoma (FL), positive results indicating that the drug is efficacious as a combination therapy will be welcome news for Novartis.