- An experimental drug cleared rectal cancer for every patient in a 12-person study.
- The scientists based in the United States said that complete recovery in every patient is “unheard of”.
- An outside expert said the results were “convincing” but we couldn’t be sure if it had been treated.
An experimental drug has emerged to rid every patient of rectal cancer with minimal side effects in an unprecedented study, but oncologists say it’s too soon to be sure they’re cured.
The drug, called dostarlimab, was given to 12 people with a certain type of rectal cancer every three weeks for six months in a small study at Memorial Sloan Kettering Cancer Center in New York.
After treatment ended, the cancer was undetectable on physical examination, endoscopy, positron emission tomography (PET) scan and magnetic resonance imaging (MRI), MSKCC researchers said in a presentation at the annual meeting of the American Society of Clinical Oncology Sunday.
The researchers said that the participants did not need any other treatment for up to a year on average, and there were no side effects bad enough to affect daily activities.
Dr. Alan B. Finock, a colorectal cancer specialist at the University of California, San Francisco, who was not involved in the study, told the New York Times that the complete calm in each patient was “unheard of.”
Dr. Andrea Krecek, an oncologist at MSKCC and co-author of the study, said there were “lots of happy tears” from trial participants when they found no further treatment was needed, according to the Times.
Standard treatment includes a grueling combination of surgery, multiple chemotherapy drugs, and radiation to destroy cancer cells, often with nasty and lasting side effects such as nerve problems, infertility, bowel and impotence.
In a press release, Cercek said the effects of standard cancer treatment on people’s quality of life are “substantial, especially in those where standard treatment will affect reproductive potential.”
“Given the high incidence of rectal cancer among young adults, this approach could have a significant impact,” Sircik said of dostarlimb’s potential.
MSKCC said cases of colorectal cancer among young adults are expected to double by 2030.
Dostarlimab works by helping the immune system identify and destroy cancer cells. The drug, which carries the brand name Jemperli, is already in use in patients with endometrial cancer, but it was not clear if it would work on malignant tumors in the rectum. The trial participants had a type of rectal cancer called mismatch repair deficiency. About 5 to 10% of people with rectal cancer have this type of cancer, in which the genes responsible for correcting any errors during cell proliferation are defective. The study cannot tell whether dostarlimb will work in patients with other types of rectal cancer.
We don’t know if it’s a cure
Hannah K. Sanoff, an oncologist at the University of North Carolina Leinberger Comprehensive Cancer Center, wrote in an editorial in the New England Journal that the study was “compelling.”
Sanoff cautioned that the outcome was incomplete for long-term cancer control. “Cancer growth occurs in 20 to 30 percent of these patients when the cancer is managed without surgery,” she said.
Sanoff added that it was not clear if the drug was safe to roll out widely because it requires specific imaging techniques, such as PET scans, which are not readily available and may mean tumor re-growth is not possible.
Sanoff said the study was also too small to show rare side effects.
Possible side effects of this drug include immune reactions in any organ such as inflammation of the lungs. The most common side effects in patients who have taken the drug for endometriosis include fatigue, nausea, diarrhea, anemia, and constipation.
“These results are very encouraging, but such an approach cannot replace the current curative treatment approach,” Sanoff said.