21 Jan 2023 • "On January 19, 2023, the Food and Drug Administration (FDA) granted accelerated approval to tucatinib (Tukysa, Seagen Inc.) in combination with trastuzumab for RAS wild-type HER2-positive unresectable or metastatic colorectal cancer that has progressed following fluoropyrimidine-, oxaliplatin-, and irinotecan-based chemotherapy. Efficacy was evaluated in 84 patients in MOUNTAINEER (NCT03043313), an open-label, multicenter trial. Patients were required to have HER2-positive, RAS wild-type, unresectable or metastatic colorectal cancer and prior treatment with fluoropyrimidine, oxaliplatin, irinotecan, and an anti-vascular endothelial growth factor (VEGF) monoclonal antibody (mAb). Patients whose tumors were deficient in mismatch repair (dMMR) proteins or were microsatellite instability-high (MSI-H) must also have received an anti-programmed cell death protein-1 mAb. Patients who received prior anti-HER2 targeting therapy were excluded. Patients received tucatinib 300 mg orally twice daily with trastuzumab (or a non-U.S. approved trastuzumab product) administered at a loading dose of 8 mg/kg intravenously on Day 1 of Cycle 1 followed by a maintenance dose of trastuzumab 6 mg/kg on Day 1 of each subsequent 21-day cycle. Patients were treated until disease progression or unacceptable toxicity. The major efficacy measures were overall response rate (ORR) and duration of response (DOR) as assessed by blinded independent central review (RECIST version 1.1.). ORR was 38% (95% CI: 28, 49) and median DOR was 12.4 months (95% CI: 8.5, 20.5). The most common adverse events (≥20%) were diarrhea, fatigue, rash, nausea, abdominal pain, infusion related reactions, and pyrexia. The most common laboratory abnormalities (≥20%) were increased creatinine, increased glucose, increased ALT, decreased hemoglobin, increased AST, increased bilirubin, increased alkaline phosphatase, decreased lymphocytes, decreased albumin, decreased leukocytes, and decreased sodium. The recommended tucatinib dose is 300 mg taken orally twice daily in combination with trastuzumab until disease progression or unacceptable toxicity Source: FDA | Read full story"