PF-05280586 is Similar to Reference Rituximab in Follicular Lymphoma

In a study to be presented at the American Society of Hematology’s annual meeting held in San Diego, California from December 1-4, 2018, researchers evaluated PF-05280586, a proposed rituximab biosimilar, versus the EU-licensed reference product, MabThera, in patients with previously untreated CD20-positive, low tumor burden follicular lymphoma.

"If approved this may help provide a more cost-effective treatment option and expand access for patients and physicians," said Jeff Sharman, MD, medical director, US Oncology Hematology Research.

The 52-week comparative study investigated the efficacy, safety, immunogenicity, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-05280586 compared with the reference. In total, 394 patients enrolled in the study and were randomized to receive either PF-05280586 (n = 196) or the reference (n = 198).

The primary end point of the study was overall response rate (ORR) at week 26, defined as the percentage of patients achieving complete response (CR) or partial response (PR) based on central review. Secondary end points included progression free survival, safety, immunogenicity, PK and PD.

Overall, the study found that ORR at week 26 was 75.5% in the PF-05280586 arm, compared with 70.7% in the reference arm, for a difference of 4.66%. The corresponding 95% CI, —4.16 to 13.47, was within the prespecified equivalence margin of ±16%.

At week 26, 11.5% of patients in the potential biosimilar arm had stable disease, compared with 19.6% in the reference. Additionally, 3.4% versus 4.3% had progressive disease in the PF-05280586 group versus the reference group, respectively.

The researchers found that the incidence of treatment-emergent adverse events (TEAEs) was similar, with 78.6% for PF-05280586 versus 72.1% for the reference. The most frequently reported TEAEs were infusion-related reactions (25.5% versus 29.9%), pruritus (6.6% versus 11.2%), and headache (8.2% versus 9.6%) in the PF-05280586 and the reference groups, respectively.

The most frequently reported grade 3 TEAEs were infusion-related reactions and hypertension, seen in 2.6% versus 0.5% and 1.0% versus 2.0% in the PF-05280586 group versus the reference group.

The researchers concluded that the efficacy, safety, immunogenicity, pharmacokinetics, and pharmacodynamics of PF-05280586 and the reference were similar at the conclusion of the study at week 26.

"With a patient centered approach and over a decade of experience globally. Pfizer remains dedicated to developing and delivering high quality biosimilars with similar efficacy and safety profiles to originator medicines that help have a meaningful impact on people living with various conditions including cancer," said Joe McClellan, vice president of biosimilars development at Pfizer, in announcing the results.

Reference

Sharman J, Liberati A, Silva R, et al. A randomized, double-blind efficacy and safety study of PF-05280586 (a potential rituximab biosimilar) compared with rituximab reference product (MabThera^®) in subjects with previously untreated CD20-positive, low tumor burden follicular lymphoma (LTB-FL). Presented at the American Society of Hematology Annual Meeting, December 1-4, 2018; San Diego, California. Abstract 394. ash.confex.com/ash/2018/webprogram/Paper111248.html.