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.

Efficacy and safety of immune checkpoint inhibitors for patients with prostate cancer: a systematic review and meta-analysis

Immunotherapy has revolutionized the treatment paradigm of many cancers, however, its effectiveness in prostate cancer patients is still under question. In the present systematic review and meta-analysis, we sought for assessing the efficacy and safety of Immune checkpoint inhibitors (ICIs) in patients with prostate cancer. PubMed, Scopus, Web of Science, and EMBASE databases were searched on Aguste 19, 2022. Thirty five studies met the eligibility criteria. The median overall survival (mOS) of all treatments was 14.1 months, with the longest and shortest mOS was seen among patients who received anti-CTLA-4 monotherapy and anti-PD-1/PD-L1+anti-CTLA-4 regimen at 24.9 and 9.2 months, respectively. Noteworthy, all types of adverse events had the lowest incidence in the anti-PD-1/PD-L1 monotherapy group. Considering the ICI monotherapy regimens, we found that fatigue, diarrhea, and infusion reaction had the highest incidence rates. Future studies evaluating the efficacy and safety of novel combination therapies with ICIs are warranted.

Safety and efficacy of avelumab plus carboplatin in patients with metastatic castration-resistant prostate cancer in an open-label Phase Ib study

BACKGROUND

Single-agent PD-1/PD-L1 inhibitors have shown limited efficacy in unselected mCRPC. The evidence of a survival benefit with sipuleucel-T and ipilimumab, provides a rationale to study further increasing immunogenicity in mCRPC through combinations.

METHODS

Safety and efficacy avelumab plus carboplatin was investigated in a single-arm Phase Ib study in mCRPC, progressing to at least one taxane and one androgen-receptor inhibitor. The primary endpoint was safety. Secondary endpoints included PSA/radiographic responses, progression-free survival (PFS) and overall survival (OS). Germline/somatic mutation analysis was performed.

RESULTS

In total, 26 patients were included. Patients were heavily pretreated: 76.9% received ≥3 and 42.3% ≥4 prior lines. A DNA damage repair (DDR) alteration was found in three patients (11.5%). The safety profile was acceptable with 73% Grade 3-4 treatment-related adverse events. PSA response rate ≥50% was seen in 7.7% of patients. The objective response rate was 17.6%, including one complete response (5.9%). Two of these responders had a known DDR alteration (one BRCA2, one ATM). The median response duration was 6 months. Median radiographic PFS was 6.6 months (95% CI 4.28-9.01), and median OS 10.6 months (95% CI 6.68-NR).

CONCLUSIONS

Avelumab plus carboplatin has an acceptable safety profile and was associated with a prolonged OS given the heavily pretreated population.

Influence of Androgen Deprivation Therapy on the PD-L1 Expression and Immune Activity in Prostate Cancer Tissue

Immune checkpoint inhibitors have become a promising new therapy for cancer treatment. However, due to prostate cancer’s high heterogeneity and immune-suppressive tumour microenvironment, clinical trials with immune checkpoint inhibitors for prostate cancer resulted in low or no response. This descriptive and retrospective study investigates the influence of androgen deprivation therapy (ADT) on PD-L1 expression and CD8+ T-cell tumour infiltration and activity in primary prostate cancer tissue. Therefore, immunohistochemistry was used to assess PD-L1, CD8+ T-cell, and the immune activation marker Granzyme B (GrB) in PCa tissue before and under ADT. In line with previous studies, few prostate cancer tissues showed PD-L1 expression and CD8+ T-cell infiltration. However, PD-L1 expression levels on tumour cells or infiltrating immune cells above 5% generated an immune-suppressive tumour microenvironment harbouring hypofunctional CD8+ T-cells. Moreover, analysis of a longitudinal patient cohort before and under ADT revealed that ADT increased hypofunctional CD8+ T cells in the tumour area suggesting a tumour immune milieu optimal for targeting with immunotherapy.

Immunotherapy in Advanced Prostate Cancer-Light at the End of the Tunnel?

Immunotherapeutic treatment approaches are now an integral part of the treatment of many solid tumors. However, attempts to integrate immunotherapy into the treatment of prostate cancer have been disappointing so far. This is due to a highly immunosuppressive, “cold” tumor microenvironment, which is characterized, for example, by the absence of cytotoxic T cells, an increased number of myeloid-derived suppressor cells or regulatory T cells, a decreased number of tumor antigens, or a defect in antigen presentation. The consequence is a reduced efficacy of many established immunotherapeutic treatments such as checkpoint inhibitors. However, a growing understanding of the underlying mechanisms of tumor–immune system interactions raises hopes that immunotherapeutic strategies can be optimized in the future. The aim of this review is to provide an overview of the current status and future directions of immunotherapy development in prostate cancer. Background information on immune response and tumor microenvironment will help to better understand current therapeutic strategies under preclinical and clinical development.

An Insight on Novel Molecular Pathways in Metastatic Prostate Cancer: A Focus on DDR, MSI and AKT

Prostate cancer is still one of the main causes of cancer-related death in the male population, regardless of the advancements in the treatment scenario. The genetic knowledge on prostate cancer is widely increasing, allowing researchers to identify novel promising molecular targets and treatment approaches. Genomic profiling has evidenced that DNA damage repair genes’ alterations are quite frequent in metastatic, castration resistant prostate cancer and specific therapies can interfere with this pathway, showing promising activity in this setting. Microsatellite instability is gaining attention as it seems to represent a predictive factor of the response to immunotherapy. Furthermore, the PTEN-PI3K-AKT pathway is another possible treatment target being investigated. In this review, we explore the current knowledge on these frequent genomic alterations of metastatic prostate cancer, their possible therapeutic repercussions and the promising future treatments under evaluation.

Biomarker-driven immunotherapy for precision medicine in prostate cancer

Although immunotherapy has recently revolutionized standard of care in different cancer types, prostate cancer has generally failed to show dramatic responses to immune checkpoint inhibitors. As in other tumors, the goal in prostate cancer is now to target treatments more precisely on patient's individual characteristics through precision medicine. Defects in mismatch repair, mutations in the exonuclease domain of the DNA polymerase epsilon (POLE), high tumor mutational burden and the presence of biallelic loss of CDK12 among others, are predictive biomarkers of response to immunotherapy. In the present review, we summarize the evolving landscape of immunotherapy in prostate cancer, including precision approaches and strategies to define classes of responsive patients and scale up resistance to immune checkpoint inhibitors.

Inside prostate cancer news from the 2021 ASCO Genitourinary Cancers Symposium

BACKGROUND

Prostate cancer (PC) is a heterogeneous disease that requires a personalized treatment approach for proper patient management.

AIM

We analyzed a selected overview of the most important news recently presented at the 2021 ASCO genitourinary cancer symposium.

RESULTS

In particular, we focused on the identification of predictive biomarkers as potential targets for therapy. Molecular signatures of increased T cell activity, proliferation, and hormone dependence were associated with greater probability of response to apalutamide in non-metastatic CRPC. Pathogenic variants of DDR genes mutations detected with circulating tumor DNA (ctDNA) analysis, which had a high concordance with tumor tissue analysis, might represent a useful way for selecting mutated patients for poly (adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors therapy. Loss of PTEN could be a target for ipatasertib (a pan-AKT inhibitor) associated with abiraterone in mCRPC patients.

CONCLUSIONS

The 2021 ASCO Genitourinary Cancers Symposium significantly contributed to the complex research goal of intimately understanding PC carcinogenesis with the ultimate aim of improving patient outcomes.