Combo therapy boosts survival for advanced colon cancer

People battling advanced colon cancers might have a new treatment option that could extend their survival, a new trial finds. The findings were present the at the annual meeting of the American Society of Clinical Oncology in Chicago, and should be considered preliminary until published in a peer-reviewed journal.

A combination of two experimental immunotherapy drugs plus standard chemotherapy led to a median 19.7 month survival for patients, compared to the median 9.5 months observed among folks who only got a targeted therapy called regorafenib.

“These results pave the way for further exploration of this promising treatment approach,” said study first author Dr. Zev Wainberg. He co-directs the UCLA Health GI Oncology Program, and is a researcher at the UCLA Health Jonsson Comprehensive Cancer Center.

The two experimental immunotherapy drugs were etrumadenant and zimberelimab, which activate the immune system to target cancer cells. Both are under development by Arcus Biosciences.

According to the American Cancer Society, an estimated 106,590 new cases of colon cancer will be diagnosed among Americans in 2024, and around 53,010 people will die of the illness. It’s the third-leading cause of cancer-related deaths in men and the fourth leading cause in women.

Catching any cancer early is key to controlling it, because cancers that have spread are much tougher to treat.

The new trial involved 112 patients with metastatic colorectal cancers who’d already undergone chemotherapy (oxaliplatin and irinotecan-containing regimens).

These patients were randomly placed into two groups. Seventy-five received EZFB: “etrumadenant/zimberelimab plus a standard chemotherapy (what doctors call mFOLFOX-6 plus bevacizumab), while the other 37 received the targeted cancer therapy regorafenib alone.

According to Cancer Research UK, regorafenib is a type of targeted cancer drug called a cancer growth blocker. It works by interrupting signals cancer cells need to grow and also prevents those cells from forming new blood vessels.

In the study, the combo therapy nearly doubled overall patient survival times, compared to regorafenib alone, and it also greatly improved what’s known as “progression-free survival,” meaning time elapsing without any further cancer growth.

Progression-free survival with the combo treatment was 6.2 months compared to 2.1 months for those in the targeted therapy only group, the researchers reported.

Finally, “treatment with the novel combination therapy either partially or completely shrank tumors in 17.3% of patients,” according to a UCLA news release. “For patients on regorafenib only, 2.7% had tumor shrinkage.”

“The improvement in both progression-free survival and overall survival observed with the EZFB combination represents a significant advancement in the management of refractory metastatic colorectal cancer,” Wahlberg said in a UCLA news release.

The combo regimen had “an acceptable safety profile,” with side effects roughly equivalent to those experienced by patients who got standard chemotherapy, Wainberg and colleagues noted.

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