Natural Killer Cell Infiltration in Prostate Cancers Predict Improved Patient Outcomes.

BACKGROUND: Natural killer (NK) cells are non-antigen specific innate immune cells that can be redirected to targets of interest using multiple strategies, although none are currently FDA-approved. We sought to evaluate NK cell infiltration into tumors to develop an improved understanding of which histologies may be most amenable to NK cell-based therapies currently in the developmental pipeline. METHODS: DNA (targeted/whole-exome) and RNA (whole-transcriptome) sequencing was performed from tumors from 45 cancer types (N = 90,916 for all cancers and N = 3365 for prostate cancer) submitted to Caris Life Sciences. NK cell fractions and immune deconvolution were inferred from RNA-seq data using quanTIseq. Real-world overall survival (OS) and treatment status was determined and Kaplan-Meier estimates were calculated. Statistical significance was determined using X2 and Mann-Whitney U tests, with corrections for multiple comparisons where appropriate. RESULTS: In both a pan-tumor and prostate cancer (PCa) -specific setting, we demonstrated that NK cells represent a substantial proportion of the total cellular infiltrate (median range 2-9% for all tumors). Higher NK cell infiltration was associated with improved OS in 28 of 45 cancer types, including (PCa). NK cell infiltration was negatively correlated with common driver mutations and androgen receptor variants (AR-V7) in primary prostate biopsies, while positively correlated with negative immune regulators. Higher levels of NK cell infiltration were associated with patterns consistent with a compensatory anti-inflammatory response. CONCLUSIONS: Using the largest available dataset to date, we demonstrated that NK cells infiltrate a broad range of tumors, including both primary and metastatic PCa. NK cell infiltration is associated with improved PCa patient outcomes. This study demonstrates that NK cells are capable of trafficking to both primary and metastatic PCa and are a viable option for immunotherapy approaches moving forward. Future development of strategies to enhance tumor-infiltrating NK cell-mediated cytolytic activity and activation while limiting inhibitory pathways will be key.

Clinical outcomes in patients with metastatic castrate-resistant prostate cancer treated with abiraterone with or without ongoing androgen deprivation therapy: A retrospective case-control study.

INTRODUCTION: Abiraterone and concurrent androgen deprivation therapy (ADT) are used in the treatment of patients with metastatic castration-resistant prostate cancer. Recently, it has been suggested that the use of abiraterone alone (without ADT) may have comparable efficacy to abiraterone with ongoing ADT. Here, we sought to assess the impact of ADT cessation in patients beginning abiraterone for castration-resistant prostate cancer. METHODS: We identified 39 patients at our institution who received abiraterone alone (with discontinuation of ADT) between 2011 and 2022. We then procured a comparable group of 39 patients (matched by age, Gleason score, and prostate-specific antigen [PSA] level) who received abiraterone with ongoing ADT during the same period. We assessed and compared clinical outcomes in the two groups (abiraterone-alone vs. abiraterone-ADT) with respect to PSA response rates, PSA progression-free survival, and overall survival. Results were adjusted using Cox proportional-hazards multivariable models. RESULTS: The median PSA before treatment initiation was 12.7 (range: 0.2-199) ng/mL in the abiraterone-alone group and 15.5 (range: 0.6-212) ng/mL in the abiraterone-ADT group. Use of abiraterone alone adequately suppressed testosterone levels in 35/37 (94.6%) patients. Patients receiving abiraterone alone had a median PSA reduction of 80.2% versus 79.5% in patients receiving abiraterone plus ADT. The median PSA progression-free survival in patients receiving abiraterone alone was 27.4 versus 25.8 months in patients receiving abiraterone plus ADT (hazard ratio [HR] 1.10; 95% confidence interval [CI] 0.65-1.71; p = 0.82). In addition, abiraterone alone was associated with an overall survival of 3.6 versus 3.1 years in patients receiving abiraterone plus ADT (HR 0.90; 95% CI 0.50-1.62; p = 0.72). There were no differences in PFS or OS between groups after performing Cox multivariable regression analyses. CONCLUSION: Use of abiraterone alone was associated with comparable clinical outcomes to patients who received abiraterone together with ADT. Further prospective studies are warranted to evaluate the impact of abiraterone alone on treatment outcomes and cost savings.

Impact of piflufolastat F-18 PSMA PET imaging on clinical decision-making in prostate cancer across disease states: A retrospective review.

INTRODUCTION: Piflufolastat F-18 (18F-DCFPyL) prostate-specific membrane antigen (PSMA) positron emission tomography (PET) imaging is approved by the US food and drug administration for initial staging of high-risk prostate cancer, biochemical recurrence (BCR), and restaging of metastatic prostate cancer. Here, we sought to assess how its integration into clinical care may have impacted the management of patients. METHODS: We identified 235 consecutive patients who underwent an 18F-DCFPyL PET scan from August 2021 to June 2022. The median prostate-specific antigen at the time of imaging was 1.8 ng/mL (Range: 0-3740 ng/mL). Descriptive statistics were used to analyze its impact on clinical care for a subset of 157 patients with available treatment information: 22 for initial staging, 109 with BCR, and 26 patients with known metastatic disease. RESULTS: PSMA-avid lesions were detected in 154/235 (65.5% of) patients. In patients undergoing initial staging, 18/39 (46.2% of) patients had extra-prostatic metastatic lesions; 15/39 (38.5% of) scans were negative and 6/39 (15.4%) had equivocal results. 12/22 (54.5% of) patients had a change in their treatment plan post-PSMA PET scan while 10/22 (45.5%) had no change in their treatment plan. In the BCR cohort, 93/150 (62.0%) had a local recurrence or metastatic lesions. Equivocal and negative scans accounted for 11/150 (7.3%) and 46/150 (30.7%) of scans, respectively. 37/109 (33.9% of) patients had a change in their treatment plan, while treatment was not altered in 72/109 (66.1% of) cases. In patients with metastatic disease, 43/46 (93.5%) had PSMA-avid lesions identified; equivocal and negative scans accounted for 2/46 (4.3%) and 1/46 (2.2%) of scan results, respectively. 6/26 (23.1%) had their tentative treatment plan adjusted after the PSMA PET scan. No change in the treatment plan was observed in 20/26 (76.9% of) cases. CONCLUSION: Integration of F-18 PSMA PET imaging impacted clinical decision-making and subsequent management across all stages of prostate cancer. It remains to be seen whether this translates into superior survival outcomes.