Former US President Jimmy Carter doesn’t need further treatment for the metastatic melanoma that spread across his liver and brain. Former President Carter has been able to recover miraculously because of a drug Keytruda, which is among the new drugs that focus on treatment called immunotherapy.

Immunotherapy-based drugs take help from a person’s own immune system for fighting the cancer, in the case of Carter it was melanoma, which takes nearly 10,000 lives in America every year. Some refer to the treatment Keytruda as the ‘golden age of chemotherapy drugs’ and a ‘miracle cure’.

The scientific name of the treatment Keytruda is pembrolizumab. It was introduced at the American Society of Clinical Oncology conference in Chicago in 2014 when a team of Israeli and American scientists described the secret to the drug’s success: the PD-1 pathway.

Usually when an infection occurs in the body, the immune system is alerted by some cells. On getting alerted, the immune system activates what are known as T-cells. T-cells are the soldiers of the immune system, which find out the intruder and kill it off. But, cancer disturbs this model with the help of a PD-1 pathway.

PD-1, which is ‘programmed cell death protein 1’, is a protein that works as an immune checkpoint. To avoid being attacked and destroyed, cancer cells invade the PD-1 pathway, which in turn prevents T-cells activation.

Keytruda and other immunotherapy drugs obstruct the PD-1 pathway. In its absence, the cancer can be seen by the T-cells, and it fails to multiply undetectably. Dr. Jacob Schachter, one of the Israeli researchers, said, “This medicine is a miracle cure—it’s a real breakthrough”.

After the presentation, the FDA granted the maker of Keytruda, Merck, a ‘breakthrough therapy’ designation, a move to fast-track drugs for grave conditions.