Inhibition of the checkpoint protein programmed cell death protein 1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1), have been an increased focus of immunotherapy strategies across all of oncology. In few other disease types have we made advances as quickly as we have in bladder cancer.
PD-1 and PD-L1 work primarily to suppress an overresponse of the immune system, protecting the body from itself. In healthy individuals, PD-1 is expressed in immune cells, including T cells. PD-L1 meanwhile, is expressed on cells throughout the body, hematopoietic and nonhematopoietic alike. When an inflammation event occurs, PD-1 will bind its ligand to inhibit T-cell induced apoptosis.
Cancer cells have been able to utilize this checkpoint system by expressing PD-L1, disguising cancer cells with the rest of our tissue. As high levels of PD-L1 expression have been linked worsened prognosis in bladder cancer, checkpoint inhibition has been an area of intensive research.
By inhibiting PD-1 or PD-L1, we’re able to turn the checkpoint off, taking away the cancer’s defense. Now, in 2018 we’re able to fight back.