Dr. Luis A. Diaz, Jr. on Pembrolizumab For MMR-Deficient Colorectal Cancer

Luis A. Diaz, Jr. MD, associate professor of Oncology, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, discusses the efficacy of PD-1 inhibitor pembrolizumab (Keytruda) in heavily pretreated colorectal cancer patients with mismatch repair (MMR).

Previously, MMR deficiency was primarily seen as a prognosis marker, and in late stage colorectal cancer it was typically linked to worse prognosis, said Diaz.

His team hypothesized that MMR deficient tumors may have immunogenic properties and could response positively to anti-PD1 therapies.

Many of the patients in the study treated with anti-PD1 therapy had advanced stage cancer, had failed several lines of previously therapy, and were in hospice care at the time of the trial, said Diaz.

Patients with advanced disease responded dramatically, said Diaz. Tumor markers came down, tumors shrank, and overall clinical response improved.

Anti-PD1 therapy could be beneficial not only for colon cancer patients, but patients with multiple tumors types that have mismatched repair deficiency, said Diaz.