This breakthrough drug trial saw cancer vanish in every patient

More than a dozen rectal cancer patients in the United States have seen their cancer disappear after undergoing experimental immunotherapy, in what doctors are calling an astonishing result.

The patients, who were part of a small clinical trial led by researchers from New York’s Memorial Sloan Kettering (MSK) Cancer Center, saw their tumours vanish after being treated with an experimental drug called dostarlimab.

Details of the trial were published on Sunday in the New England Journal of Medicine.

The paper described the results of 12 patients with rectal cancer, all of whom saw their cancer vanish after treatment with dostarlimab.

Participants received a dose of dostarlimab every three weeks for six months, with the idea being that they would need to undergo standard treatments of chemotherapy, radiation therapy and surgery following treatment.

However, researchers found that in every case, the cancer was cleared through the experimental treatment alone.

The trial has been hailed as a first in cancer treatment, with one of the paper’s authors, Dr Luis Diaz Jr of Memorial Sloan Kettering, telling the New York Times that 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,” he said.

Immunotherapy harnesses the body’s own immune system to identify and destroy cancer cells.

The trial focussed on a subset of rectal cancer patients whose cancer had a specific mutation, MSK said in a statement.

This sort of rectal cancer, known as "mismatch repair-deficient" (MMRd) rectal cancer, tends to respond poorly to standard chemotherapy regimens. In the trial, researchers wanted to investigate if immunotherapy alone could