FDA approves pembrolizumab as first-line treatment for colorectal cancer

Reviewed by Emily Henderson, B.Sc.Dec 18 2020

The FDA recently approved the immunotherapy drug pembrolizumab as a first-line treatment for patients with certain types of advanced colorectal cancer. This is the 9th FDA approval supported by Stand Up To Cancer® (SU2C) research.

Patients newly diagnosed with advanced or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) colorectal cancer previously would have been prescribed pembrolizumab only after exhausting standard chemotherapy treatments.

The FDA approved pembrolizumab, also known under the brand name Keytruda, as first-line treatment for metastatic MSI-H--dMMR colorectal cancer based on early results from a phase III clinical trial, which was partially funded by an SU2C grant.

When compared to traditional treatment, pembrolizumab was superior with fewer side effects for MSI-H--dMMR colorectal patients. There are other solid tumor cancers in adults and children that have these same MSI-H--dMMR defects, so our research may also have ramifications for other cancer types."

Luis A. Diaz, MD, Head of the Division of Solid Tumor Oncology, Memorial Sloan Kettering Cancer Center, Leader of the SU2C Colorectal Cancer Dream Team

Around 4-5% of metastatic cancer tumors have MSI-H--dMMR biomarkers, which result from the inability of cells to repair mistakes made during the cellular division process and can lead to more tumor development.

The study involved 307 MSI-H--dMMR colorectal cancer patients in 23 countries who were treated either with pembrolizumab or standard chemotherapy. Pembrolizumab targets and blocks a protein called PD-1 that can prevent immune cells called T cells from eliminating cancer cells effectively.

Dr. Diaz and his team found that MSI-H--dMMR colorectal cancer patients treated with pembrolizumab didn't see their cancer spread for a median 16.5 months, compared to patients treated with standard chemotherapy who saw their tumors grow after a median 8.2 months.

Patients receiving standard chemotherapy also had more severe side effects than patients receiving pembrolizumab. The complete study results were published in the New England Journal of Medicine on December 2, 2020.

"The Stand Up To Cancer Colorectal Cancer Dream Team has made a significant contribution to an improved treatment option for MSI-H--dMMR colorectal patients," said Nobel laureate Phillip A. Sharp, PhD, chair of Stand Up To Cancer's Scientific Advisory Committee and an Institute professor at the David H. Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology. "This is a great example of how Stand Up To Cancer's collaborative research model has a direct impact on cancer patients' lives."

Colorectal cancer is the second most common cause of cancer death among American men and women combined and nearly 148,000 Americans will receive a new diagnosis of colon or rectal cancer in 2020.

While colorectal cancer death rates have declined significantly due to increased screening and improvements in treatment, about 1 in 3 adults age 50 or older do not get the recommended screening.

New cases of colorectal cancer are occurring at a growing rate among young and middle-aged adults in the US, with the number of cases of colorectal cancer in people under 50 expected to almost double by 2030.

As colorectal cancer continues to disproportionately impact people of color (Black people have the highest rates of colorectal cancer of any racial or ethnic group in the US), improvements in screening and new precision and targeted treatments must reach all patients. SU2C announced a Health Equity Initiative in January 2020.

The initiative requires all future teams seeking Stand Up To Cancer funding to address recruitment and retention of patients from different ethnic and racial groups and underserved communities to improve diverse participation in cancer clinical trials.

The initiative also includes collaborations with advocacy groups and industry and corporate supporters to move research and public awareness efforts forward.