Proposed biosimilar ABP 980 appears comparable to Herceptin for HER-2–positive breast cancer

Top-line data from a randomized phase 3 study suggest the drug ABP 980 could be an effective biosimilar to trastuzumab for the treatment of patients with HER-2–positive early breast cancer, according to a press release from the agent’s manufacturers.

The multicenter, double blind, active-controlled study included 725 women with HER-2–positive early breast cancer. Researchers randomly assigned 364 of them to ABP 980 (Amgen/Allergan), and the other 361 received trastuzumab (Herceptin, Genentech).

In the neoadjuvant setting, patients received chemotherapy with epirubicin and cyclophosphamide every 3 weeks for four cycles.

They subsequently received ABP 980 or trastuzumab plus paclitaxel every 3 weeks for four cycles. Surgery was performed 3 to 7 weeks after the last dose.

In the adjuvant setting, women received ABP 980 or trastuzumab every 3 weeks for up to 1 year from the start of their assigned treatment regimen in the neoadjuvant setting.

Women assigned ABP 980 in the neoadjuvant setting continued to receive the agent in the adjuvant setting. Women assigned trastuzumab in the neoadjuvant setting received either ABP 980 or trastuzumab in the adjuvant setting based on an allocation determined at the time of randomization.

Results showed ABP 980 was not inferior to trastuzumab, according to the press release. However, researchers could not make an assessment of superiority based on pathologic complete response, the study’s primary efficacy endpoint.

“We believe this study confirms no clinically meaningful differences between ABP 980 and trastuzumab, and we look forward to continued discussions with regulatory authorities,” Sean E. Harper, MD, Amgen’s executive vice president of research and development, said in the press release. “Biosimilars are approved based on the analytical, nonclinical and clinical data, and we believe that the totality of the evidence we’ve generated supports ABP 980 as highly similar to the reference product.”

In the neoadjuvant setting, more patients treated with ABP 980 experienced adverse events. Most likely were unrelated to ABP 980, according to investigators.

Serious adverse events were comparable between treatment groups in the adjuvant setting, which did not include chemotherapy.

Researchers reported comparable immunogenicity between the two agents.

“These results provide significant clinical evidence that ABP 980 could be an important biosimilar treatment option for patients with HER-2–positive early breast cancer,” David Nicholson, chief research and development officer at Allergan, said in the release.

Trastuzumab, a monoclonal antibody, is approved for adjuvant treatment of HER-2–positive early-stage breast cancer; first-line treatment with paclitaxel for HER-2–positive metastatic breast cancer; single-agent treatment of patients with HER-2–positive metastatic breast cancer who already received chemotherapy; and in combination with chemotherapy for HER-2–positive metastatic cancer of the stomach or gastroesophageal junction who have not received prior therapy for metastatic disease.