The beginning of End of Cancer

Around 12 lakh Cancer cases are diagnoses in India each year out of these around 7- 8 lakhs die each year. The reasons for this in most of the cases is that most of our patients present in advance stage. Cancer is curable till stage 3 but in stage 4 we prolong the life span of cancer patients and decrease their suffering by chemotherapy, Radiotherapy, pain and palliative medicines. But now the with the advent of Immunotherapy Drugs we can think of Curing this emperor of all maladies even in stage 4 and there are many cancer hospitals in India that specialize in the same.

Unlike Chemotherapy which kills the cancer cell directly by damaging the DNA or stopping the formation of further DNA material, Immunotherapy drugs restores the lost function of T cells.

Now lets discuss in very simple way how cancer develops and why our body is not able to control it. Daily numerous mutation occurs in us that can lead to cancer formation but we have a set of very tightly regulated Genes like MMR (Mis Match Repair Genes) which repair our damaged cells by editing it like a super computer. This is called proof reading. But rarely when any mutation escapes this proof reading mechanism then the affected mutation can lead to cancer. As second stage of defence T Lymphocytes migrate near Cancerous cells to kill it but are not able to eliminate it because Canceous cells makes the T cell ineffective though T cells are still in the Cancer cell micro environment. Now why this happens is very interesting and it depicts how clever a cancer cell is. lets start understanding it this way. we all have T lymphocytes and its major function is to eliminate any foriegn pathogens and these are the integral part of our natural defence. T Lymphocytes kills the micro organisms by MHC mediated pathway but have you imagined why these T cells don't attack our own cells or organs of body. Our cells have PD 1 receptor called Programmed Death receptor which interacts with the PDL 1 ligand on surface of T cells. This interaction of PD with PDL1 inhibits the T cells from attacking the body own cells and Organs. Now this Cancer cells are very clever and they have acquired the PDL 1 on their surface and when the T Lymphocytes approaches the Cancer Cells to kill it the PDL1 on Cancer Cells interacts with the PD 1 on T Lymphocytes and this PD1 - PDL1 binding inhibits the T Lymphocyte from killing the cancer cell. Just like example suppose the policeman is just standing near thief but not able to catch him because he cant recognise the thief who is just standing next to him. The same way the cancer cells and the T Lymphocytes are standing side to side but the T Lymphocyte is not able to kill it.

Scientists were working to abolish this interaction in tumor microenviornment and it was Dr James P Allison who finally discovered this pathway and the blocking antibody against PD 1 and PDL1 like Nivolumab, Pembrolizumab, Atezolizumab and many more.

For this pioneer revolutionary work Dr James P Allison had been awarded Nobel prize in Medicine and Physiology in 2018.

The beauty of this treatment modality is that now we are we are able to cure few percentage of patients even in stage 4 which was a dream till a decade back. These are relatively safer molecules and can be given in elderly, frail or very sick patients. These drugs are not like chemotherapy that kills the Tumor cells and other normal cells but they enhances our inherent immune systems and activate the T Lymphocytes to kill the the Cancer Cells. Hope this is the beginning of End of cancer