Advanced colorectal cancer: New immunotherapy combo may be effective

Evan Walker
Evan Walker TheMediTary.Com |
A close up of an injector extracting a dose out of a vialShare on Pinterest
Immunotherapy could help treat advanced forms of colorectal cancer. Amornrat Phuchom/Getty Images
  • Colorectal, or bowel, cancer is the third most common cancer worldwide, and the second leading cause of cancer deaths.
  • Treatments include surgery, radiotherapy, chemotherapy, or immunotherapy, but the efficacy of treatment depends on the type of bowel cancer the person has.
  • A phase 1 trial has found that two monoclonal antibodies could be effective against a common form of colorectal cancer that has, historically, not responded to immunotherapy.
  • These findings could be a first step towards more effective treatment for people with this form of colorectal cancer.

According to the World Health Organization, around 10% of cancers worldwide are colorectal (bowel) cancer. In the United States, the American Cancer Society estimates that more than 150,000 people will be diagnosed with cancer of the colon or rectum in 2024.

The risk of colorectal cancer increases with age, and most cases are diagnosed in people over the age of 50. The cause is not clear, but is thought to be a combination of genetic and environmental risk factors, including:

  • Male sex
  • A diet low in fiber, and high in animal protein, particularly red and processed meats, and saturated fats
  • Overweight or obesity
  • Smoking and alcohol consumption
  • Low levels of physical activity
  • Inflammatory bowel disease.

Treatment is more effective if the cancer is detected early, and may include surgery to remove the tumor, radiation therapy or chemotherapy to destroy cancer cells and shrink the tumor, and immunotherapy.

However, immunotherapy is effective against only some types of colorectal cancer. Now, a phase 1 trial has found that a combination of two monoclonal antibodies — botensilimab and balstilimab — was effective in 61% of people with advanced MSS colorectal cancer.

The study is published in Nature Medicine.

Justin Stebbing, professor of biomedical sciences at Anglia Ruskin University (ARU), U.K., and communicating author of the study, told Medical News Today:

“It’s the first time we’ve consistently seen durable responses in the heavily pre-treated patients with colon cancer, so I think it’s hugely exciting, especially as this affects so many people.”

All the patients in the study had microsatellite stable metastatic colorectal cancer (MSS mCRC). This common form is sometimes referred to as ‘immune cold’ as, unlike other forms of colorectal cancer, it has previously proved resistant to immunotherapy.

“It opens the door for immunotherapy to work in ‘cold tumors’, either those cancers that typically don’t respond to immunotherapy, or even those who have previously responded and done well, but then it’s stopped working. So it potentially has very broad applicability across tumor types,” Prof. Stebbing told Medical News Today.

In this study, the researchers recruited 148 patients with solid bowel tumors that had metastasized (spread to other parts of the body). All had undergone several previous treatments for their cancer.

They treated them initially with escalating doses of botensilimab, then with a combination of botensilimab and balstilimab.

Of the total cohort, 101 patients completed the six-months follow-up required for the evaluation of the treatments.

Share this Article