Immunotherapy in the Treatment of Localized Genitourinary Cancers

Importance

A true revolution in the management of advanced genitourinary cancers has occurred with the discovery and adoption of immunotherapy (IO). The therapeutic benefits of IO were recently observed not to be solely confined to patients with disseminated disease but also in select patients with localized and locally advanced genitourinary neoplasms.

Observations

KEYNOTE-057 demonstrated the benefit of pembrolizumab monotherapy for treating high-risk nonmuscle invasive bladder cancer unresponsive to bacillus Calmette-Guérin (BCG), resulting in recent US Food and Drug Administration approval. Furthermore, a current phase 3 trial (Checkmate274) demonstrated a disease-free survival benefit with the administration of adjuvant nivolumab vs placebo in muscle-invasive urothelial carcinoma after radical cystectomy. In addition, the recent highly publicized phase 3 KEYNOTE 564 trial demonstrated a recurrence-free survival benefit of adjuvant pembrolizumab in patients with high-risk localized/locally advanced kidney cancer.

Conclusions and Relevance

The adoption and integration of IO in the management of localized genitourinary cancers exhibiting aggressive phenotypes are becoming an emerging therapeutic paradigm. Clinical oncologists and scientists should become familiar with these trials and indications because they are likely to dramatically change our treatment strategies in the months and years to come.

Immune Checkpoint Inhibitors for Genitourinary Cancers: Treatment Indications, Investigational Approaches and Biomarkers

Cancers of the genitourinary (GU) tract are common malignancies in both men and women and are a major source of morbidity and mortality. Immune checkpoint inhibitors (ICI) targeting CTLA-4, PD-1 or PD-L1 have provided clinical benefit, particularly in renal cell and urothelial carcinoma, and have been incorporated into standard of care treatment in both localized and metastatic settings. However, a large fraction of patients do not derive benefit. Identification of patient and tumor-derived factors which associate with response have led to insights into mechanisms of response and resistance to ICI. Herein, we review current approvals and clinical development of ICI in GU malignancies and discuss exploratory biomarkers which aid in personalized treatment selection.

Genetic Aberrations of DNA Repair Pathways in Prostate Cancer: Translation to the Clinic

Prostate cancer (PC) is the second most common cancer in men worldwide. Due to the large-scale sequencing efforts, there is currently a better understanding of the genomic landscape of PC. The identification of defects in DNA repair genes has led to clinical studies that provide a strong rationale for developing poly (ADP-ribose) polymerase (PARP) inhibitors and DNA-damaging agents in this molecularly defined subset of patients. The identification of molecularly defined subgroups of patients has also other clinical implications; for example, we now know that carriers of breast cancer 2 (BRCA2) pathogenic sequence variants (PSVs) have increased levels of serum prostate specific antigen (PSA) at diagnosis, increased proportion of high Gleason tumors, elevated rates of nodal and distant metastases, and high recurrence rate; BRCA2 PSVs confer lower overall survival (OS). Distinct tumor PSV, methylation, and expression patterns have been identified in BRCA2 compared with non-BRCA2 mutant prostate tumors. Several DNA damage response and repair (DDR)-targeting agents are currently being evaluated either as single agents or in combination in patients with PC. In this review article, we highlight the biology and clinical implications of deleterious inherited or acquired DNA repair pathway aberrations in PC and offer an overview of new agents being developed for the treatment of PC.

Landscape of Immunotherapy in Genitourinary Malignancies

The past decade has witnessed a revolution in the development of immune checkpoint inhibitors for the treatment of multiple tumor types, including genitourinary cancers. Immune checkpoint inhibitors have notably improved the treatment outcomes of patients with metastatic renal cell carcinoma and metastatic urothelial carcinoma. In prostate cancer, the role of immunotherapy with checkpoint inhibitors is not yet established except for microsatellite instability high (MSI-H) tumors. Other immunotherapeutic approaches that have been explored in these malignancies include cytokines, vaccines, and cellular therapy. Ongoing studies are exploring the use of immunotherapy combinations as well as combination with chemotherapy and targeted therapy in these types of tumors. The use of immunotherapy beyond the metastatic setting is an active area of research. Moreover, there is great interest in biomarker development to predict response to immunotherapy and risk of toxicity. This book chapter is a comprehensive review of immunotherapeutic approaches, both approved and investigational, for the treatment of renal cell carcinoma, urothelial carcinoma, and prostate cancer.

Immunotherapy for Localized Prostate Cancer: The Next Frontier?

Cancer vaccines, cytokines, and checkpoint inhibitors are immunotherapeutic agents that act within the cancer immunity cycle. Prostate cancer has provided unique opportunities for, and challenges to, immunotherapy drug development, including low tumor mutational burdens, limited expression of PD-L1, and minimal T-cell intratumoral infiltrates. Nevertheless, efforts are ongoing to help prime prostate tumors by turning a "cold" prostate cancer "hot" and thus rendering them more susceptible to immunotherapy. Combination treatments, use of molecular biomarkers, and use of new immunotherapeutic agents provide opportunities to enhance the immune response to prostate tumors.