Breakthrough in cancer cure
GS Paper - 3 (Health and Disease)
In a medical trial, results of which were published in The Indian Express on 8 June 2022, 12 patients in the United States were completely cured of rectal cancer without requiring any surgery or chemotherapy. The trial used a monoclonal antibody called dostarlimab every three weeks for six months for the treatment of a particular kind of stage two or three rectal cancer. The study was done by doctors from the Memorial Sloan Kettering Cancer Centre in New York, and its results have been published in the New England Journal of Medicine.
What are the findings?
- The trial showed that immunotherapy alone – without any chemotherapy, radiotherapy, or surgery that have been staples of cancer treatment – could completely cure the patients with a particular kind of rectal cancer called ‘mismatch repair deficient’ cancer”.
- No cases of progression or recurrence had been reported during the follow-up, the study said.
- The response too was rapid, with symptoms resolving in 81% of the patients within nine weeks of starting the therapy.
- ‘Mismatch repair deficient’ cancer is most common among colorectal, gastrointestinal, and endometrial cancers.
- Patients suffering from this condition lack the genes to correct typos in the DNA that occur naturally while cells make copies.
- The immunotherapy belongs to a category called PD1 blockades that are now recommended for the treatment of such cancers rather than chemotherapy or radiotherapy.
- PD1 is a type of protein that regulates certain functions of the immune system, including by suppressing T cell activity, and PD1 blockade therapy looks to release the T cells from this suppression.
- The anomalies in the DNA result in cancerous growths in patients with mismatch repair deficient cancers. If you imagine the immune system to be a car, PD1 acts as the brakes for the T cells of the immune system.