A study carried out at the Memorial Sloan Kettering Cancer Center reports on some unprecedented results for an anti-rectal-cancer drug candidate: complete remission in all patients enrolled in the trial.

The study focused on the cancer drug Jemperli, made by GSK, and involved 13 participants with locally advanced rectal cancer. The results are incredibly encouraging, especially when considering that the participants did not have to undergo radiation, chemotherapy, or any type of surgery against cancer.

Stunning results

“What’s really remarkable is this is the first time I know of in solid tumor oncology where we’ve had a 100% complete response, and we’ve completely omitted the normal standard of care,” said Luis Diaz, head of the division of solid tumor oncology at Memorial Sloan Kettering and one of the doctors who designed the study.

All of the participants in the study had a rare genetic signature in their tumors known as mismatch repair deficiency (MRD), according to the authors. This mutation means that their cells were less able to repair DNA errors, which can increase the likelihood of developing cancer. Eight of the participants also had Lynch syndrome, a genetic condition that leads to mismatched DNA repairs and has a much higher chance of leading to cancer.

Some immunotherapy drugs such as Jemperli are believed to have potential effects against cancers developed by such conditions as they change how the immune system interacts with cells whose DNA strands contain errors, allowing the patients’ bodies to see and attack a tumor.

The current study also drew on previous research on the treatment of patients with mismatch repair deficiency with a compound named Keytruda, which has been granted accelerated approval by the Food and Drug Administration in May 2017 as patients with tumors that have spread beyond their original location and have tested positive for MRD. Based on those results, the team wanted to determine if immunotherapy drugs can be used for such patients even before their tumors spread.

The trial shows, although on a limited sample size, that such an approach can be extremely effective after as little as six months of treatment.

“These results are cause for great optimism, but such an approach cannot yet supplant our current curative treatment approach,” Hanna K. Sanoff, an oncologist at the Lineberger Comprehensive Cancer Center at the University of North Carolina, wrote in a New England Journal editorial accompanying the study.

Although the results are very encouraging so far, they are not definitive so far; remission is a common concern with cancer, and although none of the tumors have come back so far, we still need to wait to make sure. Even so, the results seen in this study point to a very promising new way to treat certain kinds of cancer, with much fewer downsides compared to alternative treatment options.

The paper “D-1 Blockade in Mismatch Repair–Deficient, Locally Advanced Rectal Cancer” has been published in The New England Journal of Medicine.