The US Food and Drug Administration (FDA) announced on January 18, 2019 the approval of a new biosimilar version of trastuzumab. Produced by Samsung Bioepis, this agent was dubbed Ontruzant (trastuzumab-dttb).
This is the third trastuzumab biosimilar approved by the FDA, following those by Mylan and Biocon in December 2017 (Ogivri®) and Teva and Celltrion last month (Herzuma®). As with biosimilars other than Herzuma and the reference biologic Herceptin®, this agent is approved for use in the treatment of HER2-overexpressing breast cancer and the treatment of HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma. Herzuma is not approved for the latter indication.

As with Renflexis®, Samsung Bioepis’ first FDA-approved biosimilar, Merck will market the product in the US when launched. No launch date has yet been revealed.
Mylan and Biocon had signed a licensing agreement with Roche, the manufacturer of Herceptin, which ended their patent fight, but which delayed launch. Teva and Celltrion have not yet disclosed whether a similar deal has been reached with Roche. Pfizer has an investigational trastuzumab biosimilar, and they too have signed a licensing agreement with Roche.