Immune checkpoint inhibitors are designed to restore a patient’s antitumor immune response. Thus they work by stimulating the patient's immune system to attack cancer cells.
Initial hopes that checkpoint inhibitors may be a panacea for cancer were until now disappointed. In clinical trials it could be demonstrated that they can improve clinically meaningful treatment response and survival rates. The results are encouraging but the immune checkpoint inhibitors are by far not a breathtaking leap forward!
PD-1 is a checkpoint protein on T cells. PD-1 stops the T cells from attacking other cells in the body. It does this when it attaches to PD-L1, a protein found on body cells. Some cancer cells develop immunity to T cells by producing and exposing large amounts of PD-L1 on their surfaces.
Severe autoreactive reactions can be triggered by the immune system of patients treated with checkpoint inhibitors. In these cases, the immune system attacks healthy vital organs with a potentially fatal outcome for the treated patients. Also reports by physicians were made that checkpoint inhibitors may be linked with new cases of diabetes. Investigations are ongoing.
Nivolumab has received FDA approval for the treatment of a certain lung cancer type (NSCLC) and metastatic renal cell carcinoma with progression on or after chemotherapy. In NSCLC patients nivolumab could improve survival just for 3.3 months. This shows that checkpoint inhibitors are a promising improvement in cancer therapy but they are not a disruptive new cure for cancer.