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Biosimilar to Rituxan, PF-05280586, comparable to US, EU versions of drug in trial of patients with RA

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In a phase 1 and following extension trial, PF-05280586, a biosimilar to Rituxan, demonstrated comparable pharmacokinetic activity to Rituxan as marketed in the U.S. and Europe for patients with rheumatoid arthritis, according to researchers from Pfizer.

A cohort of 220 patients with active rheumatoid arthritis (RA) who had an inadequate response to methotrexate and one or more tumor necrosis factor-alpha (TNF-a) inhibitor was studied. Patients were randomized 1:1:1 to one IV, 1,000-mg treatment with PF-05280586, Rituxan sold in the U.S. (rituximab, Genentech/Biogen Idec), rituximab as formulated for sale in Europe (rituximab-EU) followed by a second administration of the dose on day 15. At week 17, patients were given the option to enroll into an extension study with additional treatment.

Disease activity and clinical response were measured using the American College of Rheumatology (ACR) Disease Activity Score in 28 joints and C-reactive protein (DAS28-CRP). Serological samples were collected to detect the presence of CD19+ B cells, anti-drug antibodies (ADAs), neutralizing antibodies and disease activity markers.

Patients randomized to rituximab-US had higher DAS28-CRP with no other demographic differences between groups. Pharmacokinetic similarity, the primary endpoint, was demonstrated, and in all patient groups, the mean DAS28-CRP, number of tender and swollen joints and high-sensitivity CRP decreased. An ACR 20% (ACR20) response, ACR50 and ACR70 response were seen across all treatment groups. A rapid reduction of CD19+ B cells occurred by week 2 and was sustained throughout the study. The incidence, timing or titers of ADAs were similar in all three groups of patients, and neutralizing activity was not detected in the sera of patients who produced ADA-positive samples.

Eleven patients experienced serious adverse events, including five who received PF-05280586 four patients who received rituximab-US and in two patients who received rituximab-EU. – by Shirley Pulawski

Reference:

Jacobs I, et al. Paper #SAT0190. Presented at: European League Against Rheumatism Annual European Congress of Rheumatology. June 10-13, 2015; Rome.

Disclosure: All of the researchers report employment by Pfizer.