Dr. Strickler on the Results of Tucatinib Monotherapy in HER2+ CRC

John H. Strickler, MD, associate professor of medicine, Duke University School of Medicine, medical oncologist, Duke Cancer Institute, discusses the results of tucatinib (Tukysa) monotherapy in HER2-positive colorectal cancer (CRC).

The phase 2 MOUNTAINEER trial (NCT03043313) examines the efficacy of tucatinib as a monotherapy vs tucatinib plus trastuzumab (Herceptin) in patients with previously treated metastatic HER2-positive CRC.

Investigators have previously presented the data on tucatinib plus trastuzumab combination in cohorts A and B, showing a robust response rate of 38% by blinded independent central review, Strickler says. At the ESMO 2022 Annual Congress, investigators report findings from cohort C, evaluating tucatinib as monotherapy in the same patient population, which shows a low response rate of 3%, Strickler explains.

The study allowed for patients in cohort C to crossover to tucatinib combination therapy if they had not responded by 12 weeks of treatment, Strickler continues. The post crossover response rate was 18% with a disease control rate of 82%, Strickler concludes.