Immunotherapy cancer trial: Will results last long term compared to traditional therapies?

The news of an under-trial immunotherapy, resulting in complete disappearance of rectal cancer in all 12 participants, has been making waves among cancer specials. The doctors, however, have said it is just an exciting scientific development that will likely take years to become the standard in healthcare.
The study Memorial Sloan Kettering Cancer Centre-New York used a monoclonal antibody marketed GlaxoSmithKline, called Dostarlimab, for the treatment of people with a specific type of stage 2 and stage 3 rectal cancers. The drug is currently approved for treatment of endometrial cancer in the United States (US) and the European Union.
The study shows that the immunotherapy alone – without any chemotherapy, radiotherapy or surgery that have been staples of cancer treatment – completely cured patients with a particular kind of rectal cancer called a mismatch repair-deficient cancer.
All 12 patients had completed the treatment and were followed for six to 25 months. “No cases of progression or recurrence had been reported during the follow-up,” the study said. The response was also rapid with symptoms resolving in 81 per cent of the patients within nine weeks of starting the therapy.Best of Express PremiumPremiumPremiumPremiumPremium

“The study shows remarkable results. But it includes not just a small number of patients but also a very small sub-set of all colorectal cancers. The mismatch repair-deficient rectal cancer that the study addresses accounts for about five per cent of all rectal cancer cases. So, is it an advancement of science? Absolutely. Is it a miracle cure for rectal cancer? No. Even among the small sub-set of patients that the study addresses, there needs to be a study on cost-effectiveness. Monoclonal antibodies are typically very expensive therapies and are not always provided the Government even in developed countries like the UK,” said Dr VP Bhalla, surgical gastroenterolog at PSRI hospital and the current president of Indian Association of Surgical Gastroenterology.
PD1 blockades, the category of drug this monoclonal antibody falls under, are currently used in several types of mismatch repair-deficient cancers even in India, including cancers that have metastasized (or spread to other parts of the body). The therapy, however, is used along with surgery, chemotherapy and radiotherapy and not in isolation as seen in the current study.

Eliminating other treatments for rectal cancers can improve a patient’s quality of life preserving fertility, sexual health and bladder and bowel functions.
Mismatch repair deficiency is most common among colorectal, gastrointestinal and endometrial cancers. The patient lacks the genes to correct typos in the DNA that occur naturally while cells make copies.
“If you imagine the immune system to be a car, PD1 acts as the brakes for the T cells of the immune system. giving the PD1 blockades, we release the brakes and allow the T-cells to destroy cancerous growth,” explained Dr PK Julka, former professor of radiotherapy at the All India Institute of Medical Sciences-New Delhi and the current chairman of Max Oncology Daycare Centre. He did the first immunotherapy treatment in India at AIIMS in 2015.

His former colleague, Dr MD Ray, professor of surgical oncology at AIIMS, said, “The study is extremely small. The results have to be proven in a larger population… Besides, we have to look at the cost factor. The treatments cost around Rs 3-4 lakh per month. How many patients in India do you think can afford it? Chemotherapy and radiotherapy, which are much cheaper in comparison, can be used to manage these patients as well.”
He said, in addition to larger trials, there was a need to conduct a randomised control trial – the gold standard of clinical trials – to determine whether the results were better in the long-term as compared to traditional therapies.