Rodrigo Dienstmann, MD

“This is one of the most beautiful stories we have in translational precision oncology research in colorectal cancer. We have robust preclinical data, rigorous molecular diagnosis, and successful clinical results,” said formal discussant of this trial, Rodrigo Dienstmann, MD, of Vall D’Hebron Institute of Oncology in Barcelona.

“The reasons these investigators had success include careful population selection of HER2-­addicted tumors,” he continued. “The investigators needed almost 1,300 patients to identify 5.4% of patients with colorectal cancer refractory to anti-EGFR therapy who were HER2-positive according to standardized IHC/FISH criteria. They were able to validate preclinical studies suggesting that in HER2-amplified colorectal cancer, double targeting of HER2 is needed for significant antitumor activity,” he noted.

Dr. Dienstmann believes the optimal timing for HER2 testing remains to be defined, but given the lack of response to EGFR-directed therapy, upfront testing is an appealing option. “HER2 testing is readily available in molecular pathology labs. All HER2-positive colorectal cancer patients should be referred to clinical trials with matched targeted agents,” he added.

“In conclusion, HER2 is a validated therapeutic target in metastatic colorectal cancer. Trastuzumab plus lapatinib is active in the absence of a chemotherapy backbone,” he stated. ■

Disclosure: Dr. Dienstmann reported no potential conflicts of interest.