Poherdy is a biosimilar to pertuzumab (Perjeta) approved by the FDA for the treatment of HER2-positive breast cancer in adult patients.[5] It is used in combination with trastuzumab and docetaxel in patients with HER2-positive metastatic or locally recurrent unresectable breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease.[5][1] In a pivotal trial of 808 previously untreated patients with metastatic disease, the addition of pertuzumab to trastuzumab and docetaxel prolonged progression-free survival to 18.5 months versus 12.4 months in the placebo group (HR 0.62; 95% CI: 0.51–0.75; p < 0.0001).[3][1] 46% of patients with pertuzumab responded to treatment versus 29% without it.[3] The most common adverse events (>25%) included alopecia (60.9%), diarrhea (66.8%), neutropenia (52.8%), nausea, fatigue, and vomiting.[1][3] There was a higher incidence of diarrhea, rash, mucosal inflammation, dry skin, and neutropenia, including febrile neutropenia, in the pertuzumab group; fatal adverse events occurred in 2.0% of patients versus 2.5% in the placebo group.[1] The risk-benefit ratio is positive for the indicated indication.[1] The dose is 840 mg intravenously infused over 60 minutes, then 420 mg every 3 weeks infused over 30–60 minutes.[5]