Pharmacovigilance Data Show Similar Safety Profiles for Reference and Biosimilar Rituximab

Biosimilar rituximab, marketed by Laboratorio Elea in Argentina as Novex, is subject to an active pharmacovigilance program that, according to Argentine law, must periodically report its status and results to regulatory authorities. In a study published in the June 7, 2017 issue of Hematological Oncology, researchers examined these pharmacovigilance reports in an effort to compare the safety profile of biosimilar rituximab with that of its reference.

A prospective treatment registry has been in place since the launch of the rituximab biosimilar. Prescribers are directed to report the age, gender, treatment start date, related pathology, dosing, and dose frequency for each patient receiving the biosimilar treatment. After a pre-determined period of time, physicians report treatment outcomes and occurrences of adverse events. For each adverse event, treating physicians file Individual Case Safety Reports (ICSRs).

Between November 26, 2014, to February 28, 2017, physicians registered a total of 584 patients who had been prescribed the biosimilar rituximab for non-Hodgkin’s Lymphoma. Among this group, 378 patients had at least 1 follow-up and were included in the analysis.

The median treatment duration was 214 days (interquartile range: 155 to 306). A mean of 5.7 cycles of rituximab were administered (range: 1 to 12). The total number of ICSRs filed was 15, and the occurrence rate was 1 ICSR filed per 100 cycles administered. Among adverse events reported on ICSRs, 10 were reported as being serious.

The adverse events reported are as follows (1 ICSR reported 2 events):

• Infusion-related reactions (n = 8)
• Pneumonia (n = 2)
• Arrhythmia (n = 1)
• Ischemic stroke (n = 1)
• Restless leg syndrome (n = 1)
• Progressive multifocal leukoencephalopathy (n = 1)
• Cytopenia (n = 1)
• Bullous dermatitis (n = 1)

The researchers concluded that the biosimilar rituximab product demonstrated a safety profile similar to that of the reference product, and that the 2 products had comparable tolerability. The researchers further noted that the pharmacovigilance program showed great value in allowing for continuous monitoring of biosimilar product safety.