A recent study reported encouraging findings that the immunotherapy drug dostarlimab was especially effective in a phase II clinical trial of 12 patients with a subtype of rectal cancer. Writing in the New England Journal of Medicine, author Hanna K. Sanoff, MD, MPH, from the UNC Lineberger Comprehensive Cancer Center, outlined prospects for future treatment of the disease.
About 5–10% of rectal cancers are molecularly characterised as being deficient in mismatch repair enzymes (dMMR). These cancers tend to be less responsive to chemotherapy and radiation, increasing the need for surgical treatments. Unfortunately, surgery can result in notable health consequences, including nerve damage, infertility, and bowel and sexual dysfunction.
“Historical treatment of the disease has included radiation, surgery and chemotherapy, which can be debilitating despite its curative potential, pointing to the need for better and more effective treatments that can prolong longevity while maintaining quality of life,” said Prof Sanoff. “These initial findings of the remarkable benefit with the use of dostarlimab are very encouraging but also need to be viewed with caution until the results can be replicated in a larger and more diverse population.”
Still awaiting long-term findings
Prof Sanoff also cautioned that little is known about how long the benefit of the drug will last or whether it will be curative in the long-term. So far, the trial participants have only been observed for six months to two years.
“The responses in these first 12 of a planned-for 30 patients in the trial were remarkable and exceed what we would expect with the standard chemotherapy plus radiation,” Prof Sanoff said. “Although quality of life measures have not been reported yet, it’s encouraging that some of the most difficult symptoms, such as pain and bleeding, all resolved with the use of dostarlimab.”
Prof Sanoff noted there are other immunotherapy drugs that potentially could be tested against this form of rectal cancer. “As a gastrointestinal medical oncologist, I can think of nothing better for my patients than being able to offer them a drug that is more effective, less toxic and avoids surgery, chemotherapy, and radiation; that day can’t come soon enough,” she said.
