BENGALURU: The role of vaccines to stimulate the immune system to fight the Covid-19 infection has become a hot topic of debate these days. But did you know, the immune system is also fighting against cancer and this knowledge is being utilised for cancer treatment. Immunotherapy is the most recent advancement in cancer management. The understanding of our body’s immune system and its role in fighting cancer has led to discoveries. It is now understood how cancer cells increase expression of inhibitory proteins called the PDL1 proteins, which in turn suppress the ‘T’ lymphocytes.
This enables cancer cells to grow out of control without being killed by our immune system. The recent development of medicines, called checkpoint inhibitors, block the PDL1 protein and release the inhibition (in other words release the brakes) on the ‘T’ lymphocytes; thus making them active to kill the cancer cells. These medicines are called immunotherapy as they are killing cancer cells by utilising the body’s immune system. The use of immunotherapy drugs has now become an important modality in the management of many cancers.
They are being used in the treatment of melanoma, renal cell cancer (kidney cancer), lung cancer, urinary bladder cancer, head and neck cancers, liver cancers, Hodgkin’s lymphoma, cervical cancer, endometrial cancer and some colon and stomach cancers. Their use is expanding not only in Stage IV disease but in early stages too. Lung cancer, stage IV disease has always been a difficult disease to treat. A few years ago, chemotherapy was the only option of treatment, and survival was very dismal.
But in the last few years, there have been multiple advances in the form of targeted therapies, biological therapies and personalised therapies in lung cancer management. Immunotherapy has rapidly bec ome a v e r y important treatment in lung cancer. It is making a positive impact in all types of advanced lung cancers, either alone or in combination with chemotherapy. For instance, B M, a gentleman aged 87 years, came to us in March 2018 with complaints o f chronic cough. After a PET-CT scan, he was diagnosed with squamous cell carcinoma lung, stage IV disease.
In the previous era, we would have kept him on palliative care. But his son hoped to improve his father’s survival while continuing to maintain good quality of life. The tumour was found to be strongly positive for a biomarker called PDL1. He started immunotherapy in March 2018. His cough reduced after treatment, and his general condition improved. A CT scan after two months showed a good reduction in the lung mass. He continued this treatment for one year. He did not have any significant side effects. After one year, a PET-CT scan showed no evidence of the disease.
So in April 2019, his treatment was stopped completely. He continues to have no evidence of disease as on Dec. 2020. The advantage of immunotherapy drugs is the prolonged duration of response. Previous treatments like chemotherapy worked only for a limited duration. The other significant advantage is that they do not have the side effects of chemotherapy, and can even be used safely in the elderly population in whom chemotherapy would not be safe to give.
The limitation of immunotherapy is that it works well in selected patients, but unfortunately, there are no good biomarkers to help select this group of patients. The other limitation is that a few patients can have side effects if the immune system becomes overactive. These side effects are different from chemotherapy side-effects and need to be identified and treated differently. The author is consultant, Medical Oncology, Manipal Hospitals Old Airport Road