Feb 2023: Tucatinib (Tukysa, Seagen Inc.) and trastuzumab received accelerated approval from the Food and Drug Administration (FDA) for the treatment of RAS wild-type HER2-positive metastatic or unresectable colorectal cancer that has progressed after receiving fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy.
An open-label, multicenter experiment called MOUNTAINEER (NCT03043313) examined effectiveness in 84 patients. Patients needed to have previously received treatment with fluoropyrimidine, oxaliplatin, irinotecan, and an anti-vascular endothelial growth factor (VEGF) monoclonal antibody in addition to having HER2-positive, RAS wild-type, unresectable or metastatic colorectal cancer (mAb). Patients that needed to get an anti-programmed cell death protein-1 mAb also had malignancies that lacked mismatch repair (dMMR) proteins or had high microsatellite instability (MSI-H). Patients who had previously received anti-HER2 targeted therapy were not eligible.
Patients received tucatinib 300 mg orally twice daily along with trastuzumab (or a trastuzumab product not licenced for use in the United States) given at a loading dosage of 8 mg/kg intravenously on Day 1 of Cycle 1 and a maintenance dose of 6 mg/kg on Day 1 of each subsequent 21-day cycle. Patients received treatment up until the onset of unacceptable side effects.
Overall response rate (ORR) and duration of response (DOR), as determined by a blinded independent central review, were the key efficacy measures (RECIST version 1.1.). The median DOR was 12.4 months (95% CI: 8.5, 20.5), and the ORR was 38% (95% CI: 28, 49).
Diarrhea, lethargy, rash, nausea, abdominal discomfort, infusion-related responses, and pyrexia were the most frequent side effects (20%). Increased creatinine, hyperglycemia, ALT, decreased haemoglobin, AST, bilirubin, increased alkaline phosphatase, decreased lymphocytes, decreased albumin, decreased leukocytes, and decreased sodium were the most prevalent laboratory abnormalities (20%).
In conjunction with trastuzumab, a dose of 300 mg of tucatinib orally twice daily is advised until the disease progresses or there is unacceptable toxicity.
Project Orbis, an initiative of the FDA Oncology Center of Excellence, was used to carry out this review. International partners can simultaneously submit and review oncology medications using the infrastructure provided by Project Orbis. FDA and the Australian Therapeutic Goods Administration worked together on this review (TGA). At the other regulatory organisation, the application review is still proceeding.