A trial involving 18 rectal cancer patients taking the same drug, called dostarlimab, resulted in the cancer disappearing for all of them, the New York Times reported Monday.

The article continued:

Dr. Luis A. Diaz Jr. of Memorial Sloan Kettering Cancer Center, an author of a paper published Sunday in the New England Journal of Medicine describing the results, which were sponsored by drug company GlaxoSmithKline, said he knew of no other study in which a treatment completely obliterated a cancer in every patient.

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

Long-term survival used to be uncommon for individuals diagnosed with rectal cancer, even after they underwent treatment. But with treatment advances in previous years, the survival rates have improved, according to the Mayo Clinic.

“Rectal cancer begins when healthy cells in the rectum develop changes (mutations) in their DNA. A cell’s DNA contains the instructions that tell a cell what to do,” the clinic’s website said.

Per the Times report, the patients were facing difficult treatments and thought they would eventually have to move forward with the procedures because their tumors were not expected to go away.

However, no more treatment was needed. In addition, none of them experienced clinically significant complications, the article said:

On average, 1 in 5 patients have some sort of adverse reaction to drugs like the one the patients took, dostarlimab, known as checkpoint inhibitors. The medication was given every three weeks for six months and cost about $11,000 per dose. It unmasks cancer cells, allowing the immune system to identify and destroy them.

Meanwhile, Dr. Hanna K. Sanoff of the University of North Carolina’s Lineberger Comprehensive Cancer Center, who was not part of the recent study, said it remained unclear if the patients were totally cured.

When asked about the next step, Sanoff told NPR, “What I’d really like us to do is get a bigger trial where this drug is used in a much more diverse setting to understand what the real, true response rate’s going to be.”

“It’s not going to end up being 100%. I hope I bite my tongue on that in the future, but I can’t imagine it will be 100%. And so when we see what the true response rate is, that’s when I think we can really do this all the time,” she added.