ASCO GI 2021 | MOUNTAINEER-02: tucatinib in previously treated HER2+ gastric cancer

HER2 amplified gastric cancer is a subset of gastric cancer that actually had the very first targeted therapy for this disease in this space. The ToGA trial established the addition of trastuzumab to the backbone of chemotherapy improves the outcomes of this population in the first-line setting. That’s almost a decade ago and multiple trials, probably seven or eight trials trying to evaluate the effectiveness of other HER2 directed agents in this space all failed to show an improvement.

And MOUNTAINEER is built to look at the effectiveness or benefit of tucatinib added to the backbone of their standard second-line therapy, which is paclitaxel ramicurumab in the HER2 positive population. MOUNTAINEER is built on the knowledge of basically changes in HER2 amplification throughout the course of therapy. And the fact that patients may actually lose their HER2 status during the first line therapy. So all patients are required to basically confirm, and that they still have HER2 amplification before going on this study. And this is a Phase II/III study. If pre-specified, efficacy is met for Phase II, then patients will move on to the Phase III. I think MOUNTAINEER’s advantage in terms of treatment is that tucatinib is an oral agent that can be easily administered and it provides a unique opportunity to look at this treatment for this population.