Immunobiology and immunotherapy in genitourinary malignancies.

Immunotherapy has traditionally been a critical component of the cancer treatment armamentarium in genitourinary (GU) cancers. It has an established role in the management of carefully selected patients with metastatic renal cell carcinoma (RCC) [e.g., high dose interleukin-2 (IL-2)] and non-muscle invasive bladder cancer (NMIBC) [e.g., intravesical Bacillus Calmette-Guérin (BCG)]. In 2010, the sipuleucel-T vaccine was approved by the FDA for the management of metastatic castration-resistant prostate cancer (mCRPC), based on a phase III trial showing overall survival (OS) benefit compared to placebo. The immune checkpoint inhibitor nivolumab (anti-PD-1) recently received FDA approval for the management of patients with advanced RCC patients previously treated with anti-angiogenic therapy, based on OS benefit compared to everolimus. Recently, large clinical trials demonstrated meaningful clinical benefit, including durable responses, as well as a good tolerability/safety profile with the use of immune checkpoint inhibitors in advanced RCC and chemotherapy-resistant advanced urothelial carcinoma (UC), while FDA just approved atezolizumab for platinum-treated advanced UC. Numerous interesting trials in different cancers are ongoing. Several combinations of immune checkpoint blockade with chemotherapeutics, vaccines, targeted tyrosine kinase inhibitors & monoclonal antibodies, epigenetic modifiers, anti-angiogenic agents, tumor microenvironment & myeloid cell targeting therapies, metabolic modification strategies, radiation, and others, are being tested in clinical trials. Comprehensive understanding of the factors underlying antitumor immune responses in physiologically relevant animal models and humans will refine further the clinical benefit of immunotherapy. Discovery and validation of appropriate molecular biomarkers via coordinated translational research efforts, rational clinical trial designs with suitable endpoints and well-defined eligibility criteria, prospective registries/databases, careful evaluation of cost-effectiveness and safety/tolerability, adequate funding and open continuous discussions among all stakeholders will support the revolutionary nature of immunotherapy in GU cancers.