Dostarlimab

In a medical trial that has shown unprecedented results, twelve rectal cancer patients were completely cured of the disease without any surgery or chemotherapy, according to a study published in the New England Journal of Medicine.

The study, done by doctors from the Memorial Sloan Kettering Cancer Centre in New York, used a monoclonal antibody called dostarlimab every three weeks for a period of six months for the treatment of a particular kind of stage two or three rectal cancer.

What does the study say?

• The study shows that the immunotherapy alone – without any chemotherapy, radiotherapy, or surgery that have been staples of cancer treatment – can completely cure the patients with a particular kind of rectal cancer called ‘mismatch repair deficient’ cancer”.
• All 12 patients had completed the treatment and were followed for six to 25 months after. No cases of progression or recurrence had been reported during the follow-up. The response was also rapid with symptoms resolving in 81% of the patients within nine weeks of starting the therapy.

What is ‘mismatch repair deficient’ cancer?

• ‘Mismatch repair deficient’ cancer is most common among colorectal, gastrointestinal, and endometrial cancers. In it, the patient lacks 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 instead of chemotherapy or radiotherapy.
• 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 breaks for the T-cells of the immune system. By giving the PD1 blockades, we release the breaks and allow the T-cells destroy the cancerous growth.
• Earlier, this therapy was used post-surgery, but the study has shown that a surgery may not be required.
• India already has a couple of PD1 blockades available, although not the one used for this particular study.

What are the hurdles in making such a treatment accessible in India?

Cost is believed to be a major hurdle in accessing the treatment in India. An immunotherapy treatment can cost around Rs 4 lakh per month, with patients needing the treatment for six months to a year.