A clinically validated treatment for many cancers is cancer immunotherapy. Cancer vaccines, oncolytic viruses and adoptive transfer of ex vivo activated T and natural killer cells are some of the immunotherapeutic strategies. Monoclonal antibody blocking of cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD1) and such other immunotherapeutic regimes are highly successful and this has given a boost to the development of immunotherapy in India.

The background story of Cancer

It is an age-old idea to exploit the host’s immune system to treat cancer and it is based on the insight that the immune system can eliminate malignant cells during the transformation in a process termed as immune surveillance. A combination of genetic and epigenetic changes plays an important role in the birth of individual human tumours and their long life. At the same time, these changes create foreign antigens, which are also called as the neo-antigens. They should render neoplastic cells detectable by the immune system and target them for destruction. However, cancer cells manage to escape immune recognition and subsequent destruction, although the immune system is capable of noticing differences in protein structure at the atomic level. There is the development of multiple resistant mechanisms by tumours, including local immune evasion, induction of tolerance and systemic disruption of T cell signalling.

The fact that cancer cells are particularly efficient at suppressing the natural immune response is known to the scientists for long. This has made most treatments exploit other means including surgery, radiation therapy and chemotherapy to exploit other means.

The present scenario

In the present days, cancer immunotherapy is becoming more and more successful. Stimulating effector mechanisms and counteracting inhibitory and suppressive mechanisms are various approaches, which the oncology doctors in Kolkata use in immunotherapies against existing cancers. Vaccination with tumour antigens or augmentation of antigen presentations is one of the strategies used to activate effector immune cells. This leads to an increased ability of the patient’s own immune system to mount an immune response against neoplastic cells. Adoptive cellular therapy (ACT) is included in additional stimulatory strategies, which are applied in an attempt to administer immune cells directly to patients, the administration of oncolytic viruses (OVs) for the initiation of systemic antitumour immunity and the use of antibodies that target the members of the tumour necrosis factor receptor superfamily so as to supply co-stimulatory signals to enhance T cell activity. The use of antibodies as a means to diminish regulatory T-cells (CD25-targeted antibodies), the use of antibodies against immune-checkpoint molecules such as CTLA-4 and PD-1 and chemotherapy (cyclophosphamide) are some strategies to neutralize immunosuppressor mechanisms.