The researches find that the Colorectal cancer is the second leading cause of cancer death in the U.S., expected to cause about 51,000 deaths in 2019. But until now; it was unclear which drugs were most effective for which patients. Cancer Center found that identifying a metastatic colorectal cancer patient’s Consensus Molecular Sub type (CMS); could help oncologists determine the most effective course of treatment.

The Colorectal cancer

CMS also had prognostic value, meaning each subgroup was indicative of a patient’s overall survival; regardless of therapy. The results are from the multi-center Phase III CALGB/SWOG 80405 trial and published in the Journal of Clinical Oncology. CMS categorizes colorectal cancer into four distinct; biologically characterized subgroups based on how mutations in the tumor behave.

The subgroups are create using data from several research teams around the world that had previously analyze tumors of colorectal cancer patients who are treat with surgery and adjuvant chemotherapy. Although CMS classification is not based on clinical outcomes; there seemed to be patterns in how different subtypes respond to treatment.

“We wanted to understand the importance of CMS for patients with metastatic disease who are treated with the two most important first-line therapies;” says Heinz-Josef Lenz, MD, Professor of Medicine in the Division of Oncology at the Keck School of Medicine of USC and J. Terrence Lanni Chair in Gastrointestinal Cancer Research at USC Norris.

Surgery and adjuvant chemotherapy

Lenz was the lead author on the study. “We anticipated that CMS had prognostic value; but we were impressed at how strongly CMS was associated with outcomes.” The study compared the efficacy of two different therapies (chemotherapy and cetuximab versus bevacizumab) on 581 metastatic colorectal cancer patients categorized by CMS.

The data showed a strong association between a patient’s CMS subtype and both overall survival and progression-free survival. For example, patients in CMS2 had a median overall survival of 40 months compared to 15 months for patients in CMS1. CMS also was predictive of overall survival among patients on either treatment; with patients in certain subtypes faring better on one therapy over the other.

Survival for CMS1 patients on bevacizumab was twice that of those on cetuximab; whereas survival for CMS2 patients on cetuximab was six months longer than for bevacizumab. “This study establishes the clinical utility of CMS in treating colorectal cancer;” Lenz says.

Progression-free survival

“It also provides the basis for more research to uncover additional clinically significant predictive signatures within these subtypes that might better personalize patient care.”Currently; it is not possible to order patient subtyping; though multiple efforts are underway to develop an assay approved for clinical use. Lenz estimates that this could happen in a matter of months.