What the trial was testing
The MOUNTAINEER enrolled 117 patients with colorectal cancer. The study was sponsored by Seagen and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was initial testing (phase 2). Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.
What the results showed
38% tumor response rate in chemo-refractory HER2+ colon cancer.
The Lancet Oncology · 2023 · NCT03043313
These findings — that in chemotherapy-refractory HER2-positive metastatic colorectal cancer — were published in the The Lancet Oncology and represent the headline result of the study.
Researchers tracked outcomes across 117 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.
What this means for patients
For patients with colorectal cancer, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.
What you can do now
Tucatinib (Tukysa) plus trastuzumab is FDA-approved and available now for chemotherapy-refractory HER2-positive metastatic colorectal cancer — the first targeted regimen specifically approved for this group. Ask an oncologist about HER2 testing on your tumor.
Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.
Open colorectal cancer trials
Study of RMC-9805 in Participants With KRAS G12D-Mutant Solid Tumors
This study is to evaluate the safety and tolerability of RMC-9805 as monotherapy and in combination with RMC-6236 in adults with KRAS G12D-mutant solid tumors.
A Study to Evaluate ARV-6723 Alone and With Pembrolizumab in Participants With Advanced Solid Tumors
This is a study to evaluate the safety and potential anti-tumor activity of an investigational drug called ARV-6723, in participants with advanced solid tumors. This is an open-label study which means that participants and study staff will know that all participants will receive ARV-6723. The investigational drug ARV-6723 will be given as an oral tablet on its own and also in combination with other drugs. Researchers think that ARV-6723 can help the body's immune system to better recognize, attack, and destroy cancer cells in adults with advanced solid tumors. ARV-6723 is an investigational drug, and this is the first time ARV-6723 will be used in humans. Depending on the treatment assignment, the investigational drug, ARV-6723, will be given as an oral tablet either on its own (monotherapy) or in combination with pembrolizumab, either through a vein (intravenously or IV) or through an injection beneath the skin (subcutaneously or SQ). This study will include multiple parts: In Part A1 (Phase 1a), different small groups of participants will receive lower to higher doses of ARV-6723 as monotherapy or in combination with standard-dose of pembrolizumab. In Part A2 (Phase 1b), two groups of participants with specific tumor indication(s) (TBD) will receive one of two doses selected based on information from Part A1. Details of Part B will be determined based on information generated from Part A.