FDA Approves Trastuzumab-Anns, a Herceptin Biosimilar

The FDA approved trastuzumab-anns (Kajinti), a biosimilar of trastuzumab (Herceptin) for the treatment of HER2-overexpressing breast cancer, metastatic gastric or gastroesophageal junction adenocarcinoma, according to the agency.

For patients with breast cancer, trastuzumab-anns, an intravenous agent is approved for use in 2 ways. First, it can be given at an initial dose of 4mg/kg over 90 minutes, then 2 mg/kg over 30 minutes weekly for 12 weeks with paclitaxel or docetaxel or for 18 weeks with docetaxel or carboplatin. A week after the last weekly dose, 6 mg/kg of trastuzumab-anns should be administered over 30 to 90 minutes every 3 weeks for a total of 52 weeks. The second option for this patient population is for the biosimilar to be administered at 8 mg/kg over 90 minutes, then 6 mg/kg over 30 to 90 minutes every 3 weeks for 52 weeks.

For metastatic HER2-overexpressing breast cancer, the recommended regimen is at an initial dose of 4 mg/kg as a 90-minute IV infusion, then subsequent weekly doses of 2 mg/kg for 30 minutes.

For patients with metastatic HER2-overexpressing gastric cancer, it is recommended that trastuzumab-anns is administered at an initial dose of 8 mg/kg over 90 minutes then 6 mg/kg over 30-90 minutes for every 3 weeks.

The FDA approves biosimilars when it is proved that they are highly similar to an already-approved biologic product — in this case, trastuzumab – called a reference product. In order to be granted FDA approval, biosimilars must not have clinically meaningful differences in terms of safety and effectiveness from the refence product.

In the breast cancer population, most common adverse events (AEs) included fever, nausea, vomiting, infusion reactions, diarrhea, infections, increased cough, headache, fatigue, dyspnea, rash, neutropenia, anemia, and myalgia. Adverse reactions requiring interruption or discontinuation of trastuzumab product treatment include CHF, significant decline in left ventricular cardiac function, severe infusion reactions, and pulmonary toxicity.

For patients with metastatic gastric cancer, common AEs that were increased (≥ 5% difference) in patients receiving trastuzumab as compared to patients receiving chemotherapy alone were neutropenia, diarrhea, fatigue, anemia, stomatitis, weight loss, upper respiratory tract infections, fever, thrombocytopenia, mucosal inflammation, nasopharyngitis, and dysgeusia. The most common adverse reactions which resulted in discontinuation of trastuzumab treatment in the absence of disease progression were infection, diarrhea, and febrile neutropenia.

Severe AEs from the drug can include cardiomyopathy, pulmonary toxicity, and embryo-fetal toxicity.