MOUNTAINEER

NCT03043313 📎

Regimen

Experimental
Tucatinib 300 mg BID (oral) + trastuzumab Q3W
Control
single-arm

Population

HER2-positive, RAS wild-type metastatic CRC, 3L+, chemotherapy-refractory; HER2 by colorectal-specific IHC/FISH criteria.

Key finding

Cohorts A+B combined (n=84): confirmed ORR by BICR 38.1% (95% CI 27.7–49.3), 3 CR + 29 PR; grade ≥3 AEs: hypertension 7%; tucatinib monotherapy (cohort C, n=30): ORR per protocol not primary but lower; no treatment-related deaths; most common AE diarrhoea 64%. First FDA-approved anti-HER2 regimen for mCRC (2023).

Source: PMID 37142372

Timeline

    Guideline citations

    • NCCN Colon (p.32)
    • NCCN Rectal (p.42)