Investigational Rituximab Biosimilar Matches Response Rate in Follicular Lymphoma

Pfizer’s rituximab investigational biosimilar PF-05280586 met the primary endpoint of overall response rate equivalence to rituximab-EU (MabThera) as a frontline treatment for patients diagnosed with CD20-positive follicular lymphoma with low tumor burden, the company announced. 

PF-05280586 is a monoclonal antibody intended to serve as a biosimilar to rituximab-EU to treat patients with CD20-positive non-Hodgkin lymphomas, CD20-positive chronic lymphocytic leukemia, rheumatoid arthritis, and other diseases. It has not yet been determined to be biosimilar by the US Food and Drug Administration (FDA).

“We are pleased to report on our fifth proposed biosimilar monoclonal antibody with positive study results,” said Amrit Ray, MD, Global President of Pfizer Essential Health Research and Development, in the press release. “These results reinforce the potential of our proposed rituximab biosimilar in providing a safe and effective treatment option for patients.”

The phase III REFLECTIONS B3281006 trial was a double-blind phase III study that compared the safety and efficacy, pharmacokinetics, and immunogenicity of first-line PF-05280586 with those of rituximab-EU among patients with CD20-positive, low-tumor burden follicular lymphoma. Overall response rate was assessed using revised response criteria for malignant lymphoma at week 26.

Pfizer did not disclose the number of patients in each study arm but the ClinicalTrials.gov website states that the study has enrolled 394 patients overall. The company will present its study findings at a future medical meeting or publication, according to the announcement. PF-05280586 is one of seven investigational biosimilars in “mid- to late-stage” development, three of which are intended to treat cancers.

The FDA has approved rituximab in combination with hyaluronidase human (Rituxan Hycela, Genentech) for treating adults diagnosed with follicular lymphoma, diffuse large B-cell lymphoma and chronic lymphocytic leukemia. For patients with previously untreated follicular lymphoma, it may be used in combination with first-line cyclophosphamide, vincristine, and prednisolone chemotherapy, and thereafter as a single-agent maintenance therapy.