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Clinical trial to test immunotherapy for rectal cancer

Aug. 5, 2021, 9:15 AM


by Tom Wilemon

A new clinical trial seeks to determine whether immunotherapy in combination with short-course radiation followed by surgical resection could be a curative treatment for locally advanced rectal cancer.

If successful, this trial could lead to approaches that improve the rate of sphincter preservation by avoiding colostomy-requiring surgery.

Kristen Ciombor, MD, MSCI

The trial is open to patients with locally advanced microsatellite unstable rectal cancer who meet criteria for participation. Kristen Ciombor, MD, MSCI, of Vanderbilt-Ingram Cancer Center, is the principal investigator of the national trial.

“We have talked to patients and patient advocates about this as we designed the trial. Everyone was very enthusiastic about the fact that patients on this study may not even need any chemotherapy to potentially cure their disease. If this study is positive, it will lead the way to future studies potentially even considering nonoperative management of patents with rectal cancer, which could be a paradigm shift,” said Ciombor, associate professor of Medicine in the Division of Hematology and Oncology.

Sponsored by the National Cancer Institute, the phase 2 clinical trial is being administered through the ECOG-ACRIN Cancer Research Group. It will investigate the effect of nivolumab and ipilimumab when given with short-course radiation therapy, followed by surgical resection. After completion of the treatment, participating patients will be followed for at least five years.

The trial will investigate whether immunotherapies with short-course radiation followed by surgery could be an alternative to the standard treatment.

“The standard treatment approach for this kind of cancer would be upfront chemotherapy for about four months, followed by radiation with or without chemotherapy and ultimately surgery,” Ciombor said. “That surgery would require, on the basis of where the cancer is, the patient to use a temporary or permanent colostomy bag.”

However, she stressed that the primary objective of the clinical trial is to investigate whether nivolumab and ipilimumab in combination with short-course radiation can improve the pathologic complete response (lack of all signs of cancer in tissue samples at surgery) rate among patients. Secondary objectives include improving sphincter preservation, five-year survival and overall survival while also monitoring for acceptable toxicity.

“Our endpoint that we are measuring is actually the percentage of people who do not have any cancer in their surgical specimen because we think this may lead to better outcomes and lower risk of recurrence,” Ciombor said. “Then if we see a high enough percentage of patients who don’t have residual cancer in their surgical specimens, down the line, it may lead us to trials testing the ability to omit surgery, so that patients may be cured without surgery or chemotherapy. That’s the hope.”

For more information about this and other clinical trials at Vanderbilt-Ingram Cancer Center, call 1-800-811-8480.

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