Clinical implications of Wnt pathway genetic alterations in men with advanced prostate cancer.

BACKGROUND: Aberrant Wnt signaling has been implicated in prostate cancer tumorigenesis and metastasis in preclinical models but the impact of genetic alterations in Wnt signaling genes in men with advanced prostate cancer is unknown. METHODS: We utilized the Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort (PROMISE) clinical-genomic database for this retrospective analysis. Patients with activating mutations in CTNNB1 or RSPO2 or inactivating mutations in APC, RNF43, or ZNRF3 were defined as Wnt-altered, while those lacking such alterations were defined as Wnt non-altered. We compared patient characteristics and clinical outcomes as well as co-occurring genetic alterations according to Wnt alteration status. RESULTS: Of the 1498 patients included, 193 (12.9%) were Wnt-altered. These men had a statistically significant 2-fold increased prevalence of liver and lung metastases as compared with Wnt non-altered patients at the time of initial diagnosis, (4.66% v 2.15% ; 6.22% v 3.07%), first metastatic disease diagnosis (10.88% v 5.29%; 13.99% v 6.21%), and CRPC development (11.40% v 6.36%; 12.95% v 5.29%). Wnt alterations were associated with more co-occurring alterations in RB1 (10.4% v 6.2%), AR (38.9% vs 25.7%), SPOP (13.5% vs 4.1%), FOXA1 (6.7% vs 2.8%), and PIK3CA (10.9% vs 5.1%). We found no significant differences in overall survival or other clinical outcomes from initial diagnosis, first metastatic disease, diagnosis of CRPC, or with AR inhibition for mCRPC between the Wnt groups. CONCLUSIONS: Wnt-altered patients with prostate cancer have a higher prevalence of visceral metastases and are enriched in RB1, AR, SPOP, FOXA1, and PIK3CA alterations. Despite these associations, Wnt alterations were not associated with worse survival or treatment outcomes in men with advanced prostate cancer.

Repeat Next-Generation Sequencing Testing on Progression in Men With Metastatic Prostate Cancer Can Identify New Actionable Alterations.

PURPOSE: There are limited data available on the real-world patterns of molecular testing in men with advanced prostate cancer. We thus sought to evaluate next-generation sequencing (NGS) testing in the United States, focused on single versus serial NGS testing, the different disease states of testing (hormone-sensitive v castration-resistant, metastatic vs nonmetastatic), tissue versus plasma circulating tumor DNA (ctDNA) assays, and how often actionable data were found on each NGS test. METHODS: The Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort clinical-genomic database was used for this retrospective analysis, including 1,597 patients across 15 institutions. Actionable NGS data were defined as including somatic alterations in homologous recombination repair genes, mismatch repair deficiency, microsatellite instability (MSI-high), or a high tumor mutational burden ≥10 mut/MB. RESULTS: Serial NGS testing (two or more NGS tests with specimens collected more than 60 days apart) was performed in 9% (n = 144) of patients with a median of 182 days in between test results. For the second NGS test and beyond, 82.1% (225 of 274) of tests were from ctDNA assays and 76.1% (217 of 285) were collected in the metastatic castration-resistant setting. New actionable data were found on 11.1% (16 of 144) of second NGS tests, with 3.5% (5 of 144) of tests detecting a new BRCA2 alteration or MSI-high. A targeted therapy (poly (ADP-ribose) polymerase inhibitor or immunotherapy) was given after an actionable result on the second NGS test in 31.3% (5 of 16) of patients. CONCLUSION: Repeat somatic NGS testing in men with prostate cancer is infrequently performed in practice and can identify new actionable alterations not present with initial testing, suggesting the utility of repeat molecular profiling with tissue or blood of men with metastatic castration-resistant prostate cancer to guide therapy choices.

Argonaute 2 modulates EGFR-RAS signaling to promote mutant HRAS and NRAS-driven malignancies.

Activating mutations in RAS GTPases drive nearly 30% of all human cancers. Our prior work described an essential role for Argonaute 2 (AGO2), of the RNA-induced silencing complex, in mutant KRAS-driven cancers. Here, we identified a novel endogenous interaction between AGO2 and RAS in both wild-type (WT) and mutant HRAS/NRAS cells. This interaction was regulated through EGFR-mediated phosphorylation of Y393-AGO2, and utilizing molecular dynamic simulation, we identified a conformational change in pY393-AGO2 protein structure leading to disruption of the RAS binding site. Knockdown of AGO2 led to a profound decrease in proliferation of mutant HRAS/NRAS-driven cell lines but not WT RAS cells. These cells demonstrated oncogene-induced senescence (OIS) as evidenced by ß-galactosidase staining and induction of multiple downstream senescence effectors. Mechanistically, we discovered that the senescent phenotype was mediated via induction of reactive oxygen species. Intriguingly, we further identified that loss of AGO2 promoted a novel feed forward pathway leading to inhibition of the PTP1B phosphatase and activation of EGFR-MAPK signaling, consequently resulting in OIS. Taken together, our study demonstrates that the EGFR-AGO2-RAS signaling axis is essential for maintaining mutant HRAS and NRAS-driven malignancies.