After a small cancer drug study yielded the unprecedented result of 100 percent of participants entering remission, oncologists — and patients — wonder if the approach from the experimental drug trial can apply to other types of cancer.
The study out of Memorial Sloan Kettering Cancer Center in New York has oncologists excited over the prospect that immunotherapy, the treatment type used in the trial, has increasingly shown effectiveness — without surgery — against tumors with a specific abnormality. All of the trial’s participants had tumors with the abnormality known as mismatch repair (MMR) deficiency, a mutation that occurs in between 5 and 10 percent of rectal cancer cases and is also present in endometrial, bladder, breast and prostate tumors.
The Sloan Kettering trial, which began in late 2019, took 18 early-stage rectal cancer patients with the same tumor mutation who had no prior treatment and gave them the drug dostarlimab every three weeks for six months. Tumors completely disappeared in all 14 patients who had completed the treatment by the time the study published (four more remain on track with similar results), and none have required follow-up treatment.
The results mark the first time immunotherapy alone eliminated the need for chemotherapy, radiation or surgery, which can cure patients but leave them with life-altering effects like infertility, bowel and sexual dysfunction or permanent reliance on a colostomy bag.
The study authors note the earliest patient to complete the trial is more than two years post-treatment, and all patients will be monitored for at least five years to ensure no tumor regrowth or reemergence.
Even cancers in advanced stages have shown sensitivity to drugs like the one used in the trial. Known as “checkpoint inhibitors,” the drugs block a specific cancer cell protein that can cause the immune system to hold back its cancer-fighting response rather than identify and eradicate cancer. Once eradicated for a number of years, the cancers rarely return, Kopetz said.
Data from other research show 70 percent of people with metastatic colorectal tumors treated with immunotherapeutic drugs to be cancer-free five years later, he said, a huge advance in treatment for a terrible disease. Metastatic cancers are even more difficult to treat than tumors that are confined to the rectum or colon.
David Ryan, the director of clinical oncology at Massachusetts General Hospital, previously told The Post that while the treatment used in the trial could become more widely available, not everyone who can receive the treatment will have access to the specialists who will help monitor patients like the trial participants and intervene if tumors come back.
“We do worry that if recurrences happen, that they have to be picked up as soon as possible to give people the best chance,” Ryan said.
Gralow, of ASCO, said the study affirms that the future of cancer treatment is a narrower approach based on cancer type, such as a tailored plan that addresses the specific characteristics of a tumor.
“I’m excited when you see such a dramatic response,” she said of the trial results. “It gives me hope we can find such a dramatic match for other cancers, too.”