A small clinical trial conducted at Memorial Sloan Kettering Cancer Center in New York, USA, found that all 14 rectal cancer patients who received experimental immunotherapy recovered. All of these subjects had locally advanced rectal cancer with a rare mutation (defective mismatch repair, dMMR). This is the first time in the history of cancer treatment that this has happened, according to the researchers. The study results were published in the New England Journal of Medicine.
The patients were treated with dostarlimab, an immunotherapy drug developed by GlaxoSmithKline. Each patient’s cancer magically disappeared and could not be detected on physical exams, endoscopies, PET scans or MRI scans, the researchers said.
The drug costs about $11,000 per dose, according to The Times (UK). It is given to patients every three weeks for six months.
Researchers say the body’s immune cells contain a protection called a “checkpoint” to prevent them from attacking normal cells. But cancer cells can affect this protection and shut down the immune cells, allowing tumors to grow in hiding. This new approach is an immunotherapy that allows the immune system to eliminate cancer cells by blocking their “don’t eat me” signals. The treatment targets a subtype of rectal cancer in which the DNA repair system does not work. When the repair system doesn’t work, more errors are made in the protein, which the immune system recognizes and kills the cancer cells.
After a follow-up period of 6 months to 25 months after the end of the trial, all patients involved in the study showed no signs of cancer recurrence and did not need to undergo standard treatments such as surgery, radiation and chemotherapy. Another surprise of the study was that none of the patients experienced serious side effects.
The researchers said the results were surprising, with all patients in the clinical trial responding to the drug, which is almost unheard of. They coined the term “immunoablation” for this method of targeting specific tumors with immunotherapy alone, which means using “immunotherapy instead of surgery, chemotherapy and radiation to eliminate cancer.
According to the researchers, surgery and radiation for rectal cancer have permanent effects on fertility, sexual health, bowel and bladder function, and a significant impact on quality of life. With the incidence of rectal cancer rising in young people, the new approach could have a significant impact.
The researchers agreed that the trial now needs to be repeated in a larger study, noting that the small study focused only on patients with rare genetic characteristics in their tumors. But seeing complete remission in 100 percent of patients tested is a very promising early sign, they said.
