Ali T. Arafa

Background: ¹⁷⁷Lu-PSMA-617 radioligand treatment represents a major advancement in the management of metastatic castration-resistant prostate cancer (mCRPC), but key questions remain about tumor cell dynamics and evolution in patients who have received this drug. Here, we used a circulating tumor cell (CTC) capture assay to assess the prognostic value of CTC subsets defined by PSMA and EpCAM, and their dynamics, during ¹⁷⁷Lu-PSMA-617 treatment in a cohort of mCRPC patients. Methods: Using a deep learning-based holographic imaging platform combined with in-flow protein marker analysis, we prospectively analyzed serial CTC samples from patients receiving ¹⁷⁷Lu-PSMA-617 therapy at pre-treatment and on-treatment time points (n = 39 of 100 enrolled patients). PSMA and EpCAM expression on CTCs was determined by immunofluorescence staining. Proportions and absolute counts of CTC subsets delineated by PSMA and EpCAM expression were assessed in PSA50 responders (n = 19) and non-responders (n = 20). Within-patient changes in CTC subsets were compared using Wilcoxon signed-rank tests with Benjamini–Hochberg correction. Associations of CTC subset abundance and dynamics with overall survival were assessed using landmark Kaplan–Meier estimates (time zero at on-treatment sample collection) with log-rank tests and univariable Cox proportional hazards models. Results: PSMA and EpCAM expression defined three CTC subsets: PSMA+/EpCAM+, PSMA+/EpCAM−, and PSMA−/EpCAM+. The mean proportion of PSMA−/EpCAM+ CTCs increased following ¹⁷⁷Lu-PSMA-617 in both PSA50 responders (6.2% to 18.7%; p = 0.041) and non-responders (7.9% to 15.4%; p = 0.023). This corresponded to a decrease in the proportion of PSMA+/EpCAM− CTCs, whereas the proportion of PSMA+/EpCAM+ CTCs did not decline. PSMA+ CTCs remained detectable in on-treatment samples from 37/39 patients, including 17/19 PSA50 responders. Pre-treatment counts of >5 CTCs, relative to ≤5 CTCs, were associated with shorter overall survival in the PSMA+/EpCAM+ subset (HR 3.66, 95%CI 1.35–9.94, p = 0.011), with a similar but nonsignificant trend in the PSMA+/EpCAM− subset (HR 7.00, 95%CI 0.94–51.9, p = 0.057), whereas on-treatment counts were not significantly associated with survival. Finally, on-treatment declines in PSMA+/EpCAM+ (HR 0.852, p = 0.731) and PSMA+/EpCAM− (HR 0.66, p = 0.305) CTC subsets were not significantly associated with overall survival relative to sustained high levels of these cells. Conclusions: In mCRPC patients receiving ¹⁷⁷Lu-PSMA-617, PSMA+ CTCs frequently persist during treatment, and the pre-treatment abundance of PSMA+ CTC subsets may have prognostic value. These exploratory findings warrant validation in larger cohorts.

Background: ¹⁷⁷ Lu-PSMA-617 radioligand treatment represents a major advancement in the management of metastatic castration-resistant prostate cancer (mCRPC), but key questions remain about tumor-cell dynamics and evolution in patients who have received this drug. Here, we used a circulating tumor cell (CTC) capture assay to assess the prognostic capacity of CTC subset dynamics following ¹⁷⁷ Lu-PSMA-617 treatment in a cohort of mCRPC patients. Methods: Using an AI-empowered holographic imaging platform combined with in-flow protein marker analysis, we prospectively analyzed serial CTC samples from patients receiving ¹⁷⁷ Lu-PSMA-617 therapy at pre-treatment and on-treatment time points (n=39 of 100 enrolled patients). PSMA and EpCAM proteins in CTCs were determined by immunofluorescence staining. Proportions and absolute counts of CTC subsets delineated by PSMA and EpCAM proteins were assessed in PSA50 responders (n=19) and non-responders (n=20). Within-patient changes in CTC subsets were compared using Wilcoxon signed-rank tests with Benjamini-Hochberg correction. Associations of CTC subset abundance and dynamics with overall survival were assessed using Kaplan-Meier estimates with log-rank tests and univariable Cox proportional hazards models. Results: PSMA and EpCAM stratified CTCs into subsets, some of which were associated with survival outcomes following ¹⁷⁷ Lu-PSMA-617. We observed an increase in the proportion of PSMA−/EpCAM+ CTCs following ¹⁷⁷ Lu-PSMA-617, with a larger increase occurring in PSA50 responders (6.2% to 18.7%; p=0.041) than non-responders (7.9% to 15.4%; p=0.023). This corresponded to a decrease in the proportion of PSMA+/EpCAM-CTCs, whereas the proportion of PSMA+/EpCAM+ CTCs did not decline. On-treatment counts of >5 CTCs, relative to ≤5 CTCs, were associated with shorter overall survival in the PSMA+/EpCAM+ (HR 3.56, 95%CI 1.32-9.60, p=0.012) and PSMA+/EpCAM-(HR 7.50, 95%CI 0.96-52.99, p=0.054) subsets. Finally, on-treatment declines in PSMA+/EpCAM+ (HR 0.74, p=0.49) and PSMA+/EpCAM-(HR 0.61, p=0.215) CTC subsets were not significantly associated with overall survival relative to sustained high levels of these cells. Conclusions: In mCRPC patients receiving ¹⁷⁷ Lu-PSMA-617, dynamic changes in CTC subsets delineated by PSMA and EpCAM expression may have prognostic value, justifying additional evaluation.

B7-H3 Supplemental Tables 2-10.

Representativeness of our study.

Purpose:B7-H3 (CD276) represents a promising therapeutic target tested in high-risk localized and treatment-refractory metastatic prostate cancer. To guide therapeutic development and treatment strategies, we examined prostate tumors and evaluated expression, molecular features, and overall survival (OS), accounting for tissue site, hormone sensitivity status, and race. Experimental Design:A total of 8,157 prostate cancer samples with paired DNA/RNA were analyzed based on annotations by tissue site, self-reported race, and disease state: hormone-sensitive prostate cancer (HSPC), castration-resistant prostate cancer (CRPC), or neuroendocrine prostate cancer (NEPC). Expression quartiles were B7-H3–high (>75th percentile) or B7-H3–low (<25th percentile). The OS was evaluated using Kaplan–Meier and Cox proportional hazards models. Results:B7-H3 expression was broadly maintained but varied by tumor site, hormone sensitivity status, and race. High expression aligned with AR-associated transcription factors (HOXB13 and FOXA1), AR-associated pathogenic dysregulations (AR-V7, SPOP, FOXA1, and TMPRSS2:ERG fusions), and actionable surface antigens (TROP2 and NECTIN-4). Weak correlations were found for lineage-plastic program regulators (EZH2, SOX2, and ASCL1) and NEPC-associated surface antigens (DLL3 and CEACAM5). High B7-H3 expression in primary tumors and HSPCs portended adverse OS [hazard ratio (HR), 1.342 and 1.30; confidence interval (CI), 1.19–1.512 and 1.15–1.46; q < 0.0001] although it was favorable in metastatic tumors (HR, 0.823; CI, 0.719–0.942; q = 0.0048). No significant differences in OS were observed among CRPCs and NEPCs, although OS varied by race, with the poorest survival in Asian/Pacific Islander patients with metastatic prostate cancer (HR, 3.72; CI, 1.49–9.29; q = 0.012). Conclusions:Maintained B7-H3 expression in various prostate cancer settings supports its viability as a target. The associations with AR-related molecular factors, surface antigens, and investigative targets for cell therapy or antibody–drug conjugates suggest potential dual-targeting strategies.See related article by Sharma et al., p. 3365

Assessing the prevalence of TP53 mutations based on histological subtypes

Summarized broad trends observed across cancer types

Assessing the Prevalence of TP53 Mutations Based on the Site of Tumor Sequenced

Fischer Exact T-test comparison between racial subgroups