In a "small but compelling" study published Sunday in the New England Journal of Medicine, 18 patients with rectal cancer achieved complete remission, marking "the first time this has happened in the history of cancer," Gina Kolata reports for the New York Times.

Key takeaways: Defining and assessing value for next-generation therapies

Study details and key findings

For the trial, which was sponsored by GlaxoSmithKline, 18 patients with rectal cancer took a checkpoint inhibitor called dostarlimab. During the six-month study period, the medication was administered every three weeks. Dostarlimab works by exposing cancer cells, allowing the immune system to detect and destroy them.

Before the trial, "[t]hese rectal cancer patients had faced grueling treatments — chemotherapy, radiation and, most likely, life-altering surgery that could result in bowel, urinary and sexual dysfunction," Kolata writes. "Some would need colostomy bags."

When the trial began, many of the patients still believed they would have to undergo these procedures when it was over. Ultimately, no one really believed their tumors would disappear.

However, they were met with "astonishing" results, Kolata writes. "The cancer vanished in every single patient, undetectable by physical exam, endoscopy, PET scans or M.R.I. scans."

"There were a lot of happy tears," said Andrea Cercek, an oncologist at Memorial Sloan Kettering Cancer Center (MSKCC) and a co-author of the paper, which was presented Sunday at the annual meeting of the American Society of Clinical Oncology.

On average, one in five patients have some type of adverse reaction to checkpoint inhibitors like dostarlimab. But, notably, none of the patients in the trial experienced clinically significant complications.

Commentary

According to Alan Venook, a colorectal cancer specialist at the University of California, San Francisco, who was not involved with the study, the absence of significant side effects means "either they did not treat enough patients or, somehow, these cancers are just plain different."

In an editorial accompanying the paper, Hanna Sanoff of the University of North Carolina's Lineberger Comprehensive Cancer Center, who was not involved in the study, said the study was "small but compelling." However, she noted that it is still unclear whether the patients are cured.

"Very little is known about the duration of time needed to find out whether a clinical complete response to dostarlimab equates to cure," Sanoff said.

And while the results were "remarkable" and "unprecedented," Kimmie Ng, a colorectal cancer expert at Harvard Medical School, said they would need to be replicated.

Still, Luis Diaz Jr., an author of the paper from MSKCC, said he did not know of any other study in which a treatment completely eradicated a cancer in every patient.

"I believe this is the first time this has happened in the history of cancer," Diaz said.

Separately, Venook agreed, noting that a complete remission in every single patient in a trial is "unheard-of." (Kolata, New York Times, 6/5)