Adalimumab Biosimilar Meets Primary Endpoint in Rheumatoid Arthritis Trial

A biosimilar to adalimumab, at the moment known as PF-06410293, met its primary endpoint in a phase 3 trial, according to early top-line results announced by Pfizer late last week.

The multinational double blind trial includes nearly 600 patients with rheumatoid arthritis (RA), and compares the investigational biosimilar’s efficacy and safety directly alongside adalimumab (Humira/AbbVie), the wildly successful anti-inflammatory.

The endpoint was an equivalent improvement measured by the American College of Rheumatology 20 (ACR20) response rate at Week 12. Such a response would be “greater than or equal to (≥) 20 percent (%) improvement in tender joint count; ≥ 20% improvement in swollen joint count” and ≥ 20% improvement in three or more of five others categories, including C-reactive protein (CRP), patient self-assessment, and physician assessment.

The study, REFLECTIONS B538-02, is ongoing. Secondary endpoints include number of patients achieving an ACR20 response on a 26 week time frame, number achieving an ACR50 or ACR70 response on a 26 week time frame, disease activity score, serum drug concentration, and EULAR response, among others.

In the trial, patients receive a 40mg subcutaneous injection of either Humira or PF-06410293, both in combination with methotrexate, every other week. Patients are 18 years or older and at least four months removed from RA diagnosis, and had at least six swollen and six tender joints at baseline.

Humira is the world’s biggest-selling drug, accounting for a large portion of AbbVie’s revenue and representing north of 10 billion dollars in annual sales. It has received approval for treatment of a range of conditions, including uveitis, Crohn’s disease, psoriasis, and various forms of arthritis. Pfizer is not the first company to try to edge in on the drug’s success: Amgen’s Amjevita, another adalimumab biosimilar, received FDA approval in September.

It remains unknown when the drug, still without a formal name, will fall before the FDA and find its way to market, but the announcement on January 5th coresponded with a boost in Pfizer’s stock prices.