FDA Approves Third Trastuzumab Biosimilar, Ontruzant

Kelly Davio contributed to this article.

The FDA has approved Samsung Bioepis’ Ontruzant (trastuzumab-dttb), a biosimilar trastuzumab referencing Herceptin, for the treatment of HER2-positive breast cancer and HER2 overexpressing gastric cancer.

The drug was first approved by the European Medicines Agency in November 2017, making it the first biosimilar trastuzumab to be approved in the European Union. Since the approval, Europe has also seen the entry of 3 additional versions of biosimilar trastuzumab, Herzuma, Kanjinti, and Ogivri.

Ontruzant will now compete in the United States with the reference product, Herceptin, which in the third quarter of 2018 had earned developer Roche an estimated $5,332,998 globally. The newly approved biosimilar will also eventually compete with 2 prior FDA approved biosimilars: Ogivri, developed by Mylan and Biocon, and Herzuma, developed by Celltrion and Teva. To date, no trastuzumab biosimilars have launched in the United States, and Roche has reportedly reached an undisclosed agreement with Mylan concerning the launch of Ogivri in the United States.

Under a prior agreement, Ontruzant will be commercialized in the United States by Merck.

Samsung Bioepis recently revealed safety and efficacy results for the biosimilar at 1 year. The results, presented in an abstract at the 2018 San Antonio Breast Cancer Symposium, held in San Antonio, Texas, from December 4 to 8, 2018, reported on a study of patients with HER2-positive early breast cancer or locally advanced breast cancer who were randomized to receive either the biosimilar or its reference concurrently with chemotherapy.

Patients underwent surgery, then received treatment with either SB3 or its reference. Afterward, 367 patients—181 of whom had been treated with the reference trastuzumab and 186 of whom had been treated with the biosimilar—were enrolled.

Within the group of patients treated with the reference, 126 patients had been exposed to lots of trastuzumab, with expiry dates from August 2018 to December 2019, that had a lower antibody-dependent cell-mediated cytotoxicity (ADCC) than other lots of the reference product. The remaining 55 patients given the reference therapy were unexposed to these lots. After 30.1 months of treatment with the biosimilar and 30.2 months of treatment with the reference, there was no statistically significant difference in event-free survival between the biosimilar arm (96.7%) and the patients who were unexposed to the lower-ADCC activity lots of the reference (98.2%) (hazard ratio [HR], 1.19; 95% CI, 0.23-6.18; P = .8376).

Reference

Pegram MD, Pivot X, Cortes J, et al. Event-free survival by ADCC status from a follow-up study comparing SB3 (trastuzumab biosimilar) with reference trastuzumab for HER2 positive breast cancer in neoadjuvant setting. Presented at the 2018 San Antonio Breast Cancer Symposium, December 408, 2018; San Antonio, Texas. Abstract P6-17-09. https://www.sabcs.org/Program/Poster-Sessions/Poster-Session-6?rel=0" .