Immunotherapy May Be Effective In Certain Patients With Metastatic Colorectal Cancer

Patients with microsatellite stable (MSS) colorectal cancer, which represents 95% of all metastatic colorectal cancer cases, are more responsive to checkpoint blockade immunotherapy if the patient’s tumors have not spread to the liver, according to a study published in JAMA Network Open. Checkpoint blockade immunotherapy is an innovative treatment that helps the immune system recognize and attack cancerous cells.

The study analyzed data from 95 patients with MSS metastatic colorectal cancer who received immune checkpoint inhibitor programmed cell-death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) targeted therapy when their disease became resistant to chemotherapy. The median disease progression time for patients without liver metastases was 4 months compared to 1.5 months for those whose cancer had spread to the liver.

“When we stratified the patients by the presence or absence of liver metastases, we noted that about 20% of patients without liver metastases had a major response to anti-PD-1 or anti-PD-L1 therapy, while none of the patients with liver metastases experienced a positive response,” said Marwan Fakih, MD, co-director of the Gastrointestinal Cancer Program and the Judy & Bernard Briskin Distinguished Director of Clinical Research at City of Hope, in a press release. “Colorectal cancer patients without liver metastases could benefit from immunotherapy considerably more than patients with liver metastases.”

Colorectal cancer is the third most common cancer and the leading cause of cancer-related deaths in the United States, according to the CDC. When colorectal cancer spreads to the liver, some patients can have all tumors surgically removed; however, this is not always the case, which leads to the use of chemotherapy.

“Chemotherapy is destined to stop working, and we have to look into additional treatment options,” Fakih said in the release. “To our knowledge, this is the largest study to evaluate the impact of PD-1/PD-L1 targeting on patient response as stratified by site of metastatic disease.”

Immunotherapy in patients with MSS colorectal cancer has traditionally been seen as ineffective, according to the investigators, which leaves these patients with few treatment options.

“For patients without liver metastatic disease, PD-1/PD-L1-based therapies, particularly those combining these agents with tyrosine kinase inhibitors (TKI), hold significant promise,” Fakih said.

REFERENCE

Immunotherapy may be effective for a subgroup of metastatic colorectal cancer patients, City of Hope study finds [news release]. EurekAlert; August 9, 2021. Accessed August 10, 2021. https://www.eurekalert.org/news-releases/924641