Plaque Psoriasis Drug Candidate Shows Positive Top-Line Results in First of Two Phase III Studies

Amgen has released positive top-line results from the first of two Phase III studies of ABP 501, its candidate for the treatment of moderate-to-severe plaque psoriasis that is being developed as a biosimilar to adalimumab (Humira).

The primary endpoint for the current phase III study was percent improvement in Psoriasis Area and Severity Index (PASI) scores from baseline to Week 16 of treatment. At Week 16, PASI percent improvement from baseline was within the pre-specified equivalence margin for ABP 501 compared to adalimumab, according to a press release from Amgen. Safety and immunogenicity of ABP 501 were found to be comparable to adalimumab.

This randomized, double blind, active-controlled study evaluated safety and efficacy of ABP 501 compared to adalimumab in adults with moderate-to-severe plaque psoriasis. In all, 350 patients were enrolled and initially randomized. Of these patients, 174 patients in the ABP 501 group and 173 patients in the adalimumab group were treated. One patient in the ABP 501 group and two patients in the adalimumab group were randomized but did not receive any investigational product. The primary endpoint, PASI percent improvement, was evaluated at Week 16. Whenever possible, all assessments for a given patient were made by the same observer, the release from Amgen notes.

At Week 16, patients with a PASI 50 response or greater will remain on study for up to 52 weeks. Patients continuing with the study after Week 16 were re-randomized in a blinded fashion so that all patients initially randomized to ABP 501 continued to receive ABP 501, while those on adalimumab either continued on adalimumab or switched to ABP 501 in a 1:1 fashion. Patients will continue on treatment until Week 48, when patients will receive the final dose of ABP 501. The final efficacy assessments will be conducted at Week 50; the study will end at Week 52.

The active ingredient of ABP 501 is an anti-TNF-α monoclonal antibody, which has the same amino acid sequence as adalimumab. ABP 501 also has the same pharmaceutical dosage form and strength as adalimumab in both the United States and the European Union.

"Results from Amgen's biosimilar Phase 3 plaque psoriasis study met the primary endpoint for efficacy and showed comparable safety and immunogenicity to adalimumab, which further demonstrates the company's commitment to provide patients with access to high-quality medicines," said Sean E. Harper, MD, executive vice president of Research and Development at Amgen. "We look forward to continuing to leverage our experience and expertise in biotechnology to bring biosimilars to patients."

This is the first of two Phase III studies intended to form the basis for global regulatory submissions for ABP 501, Amgen reports.