T-Cell redirecting bispecific antibodies: a review of a novel class of immuno-oncology for advanced prostate cancer.

Novel T-cell immunotherapies such as bispecific T-cell engagers (BiTEs) are emerging as promising therapeutic strategies for prostate cancer. BiTEs are engineered bispecific antibodies containing two distinct binding domains that allow for concurrent binding to tumor-associated antigens (TAAs) as well as immune effector cells, thus promoting an immune response against cancer cells. Prostate cancer is rich in tumor associated antigens such as, but not limited to, PSMA, PSCA, hK2, and STEAP1 and there is strong biologic rationale for employment of T-cell redirecting BiTEs within the prostate cancer disease space. Early generation BiTE constructs employed in clinical study have demonstrated meaningful antitumor activity, but challenges related to drug delivery, immunogenicity, and treatment-associated adverse effects limited their success. The ongoing development of novel BiTE constructs continues to address these barriers and to yield promising results in terms of efficacy and safety. This review will highlight some of most recent developments of BiTE therapies for patients with advanced prostate cancer and the evolving data surrounding BiTE constructs undergoing clinical evaluation.

Bispecific PSMA antibodies and CAR-T in metastatic castration-resistant prostate cancer.

Prostate cancer is the most common cancer among men and the second leading cause of cancer-related deaths in men in the United States. The treatment paradigm for prostate cancer has evolved with the emergence of a variety of novel therapies which have improved survival; however, treatment-related toxicities are abundant and durable responses remain rare. Immune checkpoint inhibitors have shown modest activity in a small subset of patients with prostate cancer and have not had an impact on most men with advanced disease. The discovery of prostate-specific membrane antigen (PSMA) and the understanding of its specificity to prostate cancer has identified it as an ideal tumor-associated antigen and has revived the enthusiasm for immunotherapeutics in prostate cancer. T-cell immunotherapy in the form of bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR) T-cell therapy have shown exceptional success in treating various hematologic malignancies, and are now being tested in patients with prostate cancer with drug design centered on various target ligands including not just PSMA, but others as well including six-transmembrane epithelial antigen of the prostate 1 (STEAP1) and prostate stem cell antigen (PSCA). This summative review will focus on the data surrounding PSMA-targeting T-cell therapies. Early clinical studies with both classes of T-cell redirecting therapies have demonstrated antitumor activity; however, there are multiple challenges with this class of agents, including dose-limiting toxicity, 'on-target, off-tumor' immune-related toxicity, and difficulty in maintaining sustained immune responses within a complex and overtly immunosuppressive tumor microenvironment. Reflecting on experiences from recent trials has been key toward understanding mechanisms of immune escape and limitations in developing these drugs in prostate cancer. Newer generation BiTE and CAR T-cell constructs, either alone or as part of combination therapy, are currently under investigation with modifications in drug design to overcome these barriers. Ongoing innovation in drug development will likely foster successful implementation of T-cell immunotherapy bringing transformational change to the treatment of prostate cancer.

New therapies utilizing T-cell immunotherapy for patients with metastatic prostate cancer There are ongoing developments in therapeutic strategies for the treatment of patients with metastatic castrate-resistant prostate cancer. Many of these developments involve the activation of the immune system to target neoplastic prostate cells and tumors. Conventional immunotherapy modalities such as checkpoint inhibitors did not provide robust response in clinical study to warrant a change to the prostate cancer treatment paradigm. However, we are now seeing various agents in the form of bispecific antibodies and chimeric antigen receptor's which influence T-cell activity and are leading to interesting and promising pre-clinical and clinical results. This review article highlights the biologic rationale for employment of T-cell redirecting therapies for the treatment of prostate cancer, and reviews much of the exciting data emerging within the field.

Pretest Genetic Education Video Versus Genetic Counseling for Men Considering Prostate Cancer Germline Testing: A Patient-Choice Study to Address Urgent Practice Needs.

PURPOSE: Germline testing (GT) for prostate cancer (PCA) is now central to treatment and hereditary cancer assessment. With rising demand for and shortage of genetic counseling (GC), tools to deliver pretest informed consent across practice settings are needed to improve access to GT and precision care. Here, we report on Evaluation and Management for Prostate Oncology, Wellness, and Risk (EMPOWER), a patient-choice study for pretest video-based genetic education (VBGE) versus GC to inform urgent practice needs. PATIENTS AND METHODS: Men with PCA or at risk for PCA (family history of PCA) were eligible and could choose pretest VBGE or GC. Outcomes included decisional conflict for GT, change in genetics knowledge, satisfaction, and intention to share results with family and/or providers. Descriptive statistics summarized results with counts and percentages for categorical variables and mean ± standard deviation for continuous variables. Data were compared with Fisher's exact, chi-squared, or Wilcoxon two-sample tests. Mean change in genetics knowledge was compared with t tests. The significance level was set a priori at .05. RESULTS: Data on the first 127 participants were analyzed. Characteristics were White (85.8%), bachelor's degree (66.9%), and PCA diagnosis (90.6%). The majority chose VBGE (71%) versus GC (29%; P < .001). No differences were observed in decisional conflict for GT or satisfaction. Cancer genetics knowledge improved in both groups without significant difference (+0.9 VBGE, +1.8 GC, P = .056). Men who chose VBGE had higher intention to share GT results (96.4% VBGE v 86.4% GC, P = .02). Both groups had high rates of GT uptake (VBGE 94.4%, GC 92%). CONCLUSION: A substantial proportion of men opted for pretest VBGE, with comparable patient-reported outcomes and uptake of GT. The results support the use of pretest video to address the critical GC shortage in the precision era.