Elliott, Andrew

Abstract Endocytosis regulates receptor trafficking and signaling, yet its role in colorectal cancer (CRC) remains unclear. We analyzed transcriptomic data from 15,025 CRC tumors to evaluate gene expression in clathrin-mediated endocytosis (CME) and the endosomal sorting complexes required for transport (ESCRT) pathway. Pathway-level signatures were compared across consensus molecular subtypes (CMS) and examined in relation to oncogenic signaling programs, while individual endocytosis-related genes were evaluated for associations with clinical outcomes in an independent randomized trial cohort. Expression of CME and ESCRT pathways varied by CMS, with the highest expression in CMS4 and the lowest in CMS3. Endocytosis signatures correlated with multiple oncogenic signaling pathways, including MAPK, TGF-β, WNT, PI3K, NOTCH, and angiogenesis, suggesting broad links between endocytic activity and tumor biology. In the randomized phase III CALGB/SWOG 80405 trial, low expression of AP2M1 —a core adaptor in the CME complex—was significantly associated with longer overall survival and progression-free survival in patients treated with anti-EGFR agents, but not in those receiving anti-VEGF agents. These findings suggest that endocytic trafficking may be associated with oncogenic signaling and differential therapeutic benefit in patients with metastatic CRC. The endocytosis pathway reflects biologically relevant heterogeneity in CRC and may help guide therapeutic stratification.

Abstract 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

Abstract Natural killer (NK) cells represent key effectors of antitumor immunity, yet emerging evidence highlights populations with distinct roles in cancer. Despite such expanded diversity within the NK cell repertoire, we lack an understanding of how this heterogeneity affects immune responses and downstream clinical outcomes. Using single-cell RNA sequencing, we systematically profiled NK cells across cancer and uncovered a dichotomous phenotypic and functional landscape of tumor-infiltrating NK cells shaped by opposing intrinsic signaling programs that drive the expression of IFNG or TGFB1. These divergent programs are associated with distinct transcription factor circuits that integrate cues within the tumor microenvironment and skew NK cells toward proinflammatory or suppressive functions. We found that the capacity for NK cells to engage in either functional direction is intrinsically linked to their phenotypic identity. Canonical NK cells recruited from circulation predominantly directed suppressive TGFB1 signals toward effector CD8+ T cells in tumors. Of note, these subsets exhibited higher TGFB1 expression than intratumoral myeloid cells across tumor types. In contrast, a tissue-resident (TR) adaptive subset exhibited exclusively proinflammatory IFNG-driven profiles and was associated with prolonged survival in both primary and metastatic tumor settings. Moreover, these TR adaptive NK cells, but not other subsets, were linked to response to immune checkpoint blockade. Collectively, our study reveals a previously unrecognized regulatory axis in NK cells that shapes NK cell diversity and augments broader antitumor immune responses.

e14555 Background: Natural killer (NK) cells are innate lymphocytes that engage in direct cytotoxic responses against malignant cells and promote pro-inflammatory tumor microenvironments. While studies have predominantly focused on conventional NK cell subsets, recent findings uncovered adaptive and tissue-resident (TR) subsets with unique functional properties. The influence of distinct NK cell subsets on tumor immunobiology and clinical outcomes remains unknown. Methods: Single-cell RNA-sequencing (scRNA-seq) of primary, therapy-naïve tumors from 276 patients across 14 cancer types, as well as 39 patients treated with immune checkpoint blockade (ICB), was accessed through publicly available datasets. We employed systematic computational analyses to phenotype and examine intra-tumoral NK cells. Gene signatures for NK cell subsets were applied to bulk RNA-sequencing from 212,105 tumor samples to delineate their associations with clinical outcomes using the Caris CODEai database. Results: Six main subsets of NK cells were identified in solid tumors, including conventional CD56 dim and CD56 bright NK cells, alongside adaptive, TR adaptive, TR CD56 bright , and TR CD56 bright /adaptive subsets. Across cancer, TR adaptive NK cells emerged as the most prognostic subset, with high infiltration conferring significantly longer overall survival (HR[95% CI] = 0.68[0.66-0.69], p < 0.001) than conventional CD56 dim and CD56 bright subsets. This was also observed in cohorts of head and neck, non-small cell lung, and esophageal cancers, particularly those treated with ICB. Notably, elevated TR adaptive NK cell infiltration was more prognostic than high tumor mutational burden in these settings. This was most apparent in ICB-treated head and neck cancers (HR = 0.48[0.41-0.57], p < 0.001 vs HR = 0.90[0.76-1.04], p = 0.16). Additionally, TR adaptive NK cells were strongly correlated to the infiltration of CD8 + T cells and B cells in tumors. Underlying these observations, our scRNA-seq analyses demonstrated that TR adaptive NK cells exhibit the highest immunomodulatory activity of all subsets, expressing high levels of pro-inflammatory cytokines ( CCL3 , CXCL13 , and IFNG ) and low levels of immunosuppressive cytokines ( TGFB1 ). Mechanistically, this activity was linked to the upregulation of transcription factors associated with NK cell activation, function, and persistence and downregulation of genes related to stress response and exhaustion. Interestingly, scRNA-seq from paired pre- and post-ICB-treated tumors revealed a unique expansion of cytotoxic GZMB + TR adaptive NK cells after treatment. Conclusions: TR adaptive NK cells represent a novel subset of NK cells that may drive anti-tumor immune responses, particularly in the context of ICB treatment. Features of this unique population may be harnessed to design more effective NK cell-based therapies against solid tumors.

5022 Background: Racial disparities are evident in PCa, with Black men experiencing a higher incidence and worse survival compared to NHW patients (pts). The molecular alterations that distinguish these groups remain incompletely characterized. Herein, we investigate the clinical-genomic features that potentially contribute to the differences in outcomes between Black and NHW pts with PCa. Methods: Comprehensive next-generation sequencing of DNA (592-gene panel/whole exome) and RNA (whole transcriptome) was performed at Caris Life Sciences on PCa tissue samples (n = 5,412), collected from 2015 to 2023. Transcriptomic signatures – Androgen Receptor (AR), Neuroendocrine PCa (NEPC) scores – were calculated. Real-world overall survival (OS) data was obtained from insurance claims and was analyzed using Kaplan-Meier estimation. Results: Overall, 1,078 pts with PCa identified as Black, while 4,334 were NHW. Black pts were younger at biopsy collection than NHW pts (median age 66 vs 71 years, P < 0.001). The proportion of metastatic samples was higher in Black pts compared to NHW pts (43% vs 38%, P < 0.01). The prevalence of castrated PCa specimens was similar between Black and NHW pts (26.0% vs 25.4%, P = 0.72). Among non-castrated PCa tumors, tumors from NHW pts had more frequent alterations in TP53 , PTEN , PIK3CA , and CHEK2 , while tumors from Black pts had more SPOP and CTNNB1 mutations. In the castrate setting, TP53 and PTEN alterations were more frequent in tissue samples from NHW pts, while CDK12 and SPOP mutations were more frequent in tumors from Black pts. TMPRSS2 fusions were more prevalent in the NHW cohort across both castrated and non-castrated tumors. Tumors from Black pts had higher FOLH1 / PSMA and STEAP1 expression, elevated AR scores, but lower CD276 / B7H3 expression and NEPC scores. In the overall cohort, Black pts demonstrated a shorter median OS from diagnosis compared to NHW pts (86 vs 94 mos, P = 0.03). Black pts had a significantly longer time on treatment with enzalutamide in both the non-castrate (HR 0.82, P= 0.04) and castrate subgroups (HR 0.77, P= 0.03). Among pts with homologous recombination repair (HRR) deficiency-harboring tumors, PARP inhibitors provided a numerically longer survival benefit in Black pts than in NHW pts (21 vs 13 mos, P = 0.09). Conclusions: This multi-institutional study reveals distinct molecular profiles between Black and NHW pts with PCa. Despite having molecular features associated with better prognosis, Black men demonstrated worse survival outcomes, pointing to multifaceted determinants of disease outcomes. Notably, Black pts had improved outcomes on enzalutamide and showed potential benefit from PARP inhibitors in the presence of HRR mutations. These findings highlight genomic differences in diverse PCa populations and suggest therapeutic opportunities to address outcome disparities.

5073 Background: B7-H3 ( CD276 ) is an immunomodulatory protein overexpressed in prostate cancer (PC), representing a promising therapeutic target. However, expression of B7-H3 across PC disease states (hormone sensitive [HSPC], castration resistant [CRPC], neuroendocrine [NEPC]) and across races is poorly understood. We analyzed PC samples from a large clinico-genomic database to comprehensively characterize B7-H3 expression and elucidate its therapeutic potential in PC patients. Methods: We analyzed 7,682 PC samples with paired DNA/RNA profiling from Caris Life Sciences. Using CD276 mRNA expression measured by transcripts per million (TPM), samples were stratified into B7-H3-high (>75% centile) or low (<25% centile) groups. Annotations of HSPCs and CRPCs were based on time of biopsy collection relative to first use of androgen deprivation therapies. NEPC was defined histologically (Epstein, AJSP 2014). Transcriptomic alterations were compared using Mann-Whitney U tests. Overall survival (OS) was obtained from insurance claims data and assessed by Kaplan-Meier and Cox proportional hazards analyses. Results: B7-H3 was expressed at similar levels across specimen sites (prostate, lymph node, bone, liver, lung). HSPCs and CRPCs had similar levels of B7-H3 expression, but was reduced in NEPCs (TPM = 5.07, 4.96, 4.48; q<0.0001). While B7-H3-high was associated with worse OS in HSPCs (HR 1.32, 95CI 1.14-1.53, p=0.0002), it was associated with better OS in CRPC (HR 0.82, 95CI 0.69-0.97, p=0.018). B7-H3 expression was comparable in white, African American (AA), and Asian patients. However, Asian patients with high B7-H3 had worse outcomes (HR 4.08, 95CI 2.10-7.93, p<0.0001) while AA patients had improved outcomes (HR 0.74, 95CI 0.57-0.97, p=0.027). In co-expression analyses, B7-H3 was positively correlated with AR transcriptional co-factors ( HOXB13 , FOXA1 ) (R=0.59, 0.47; q<0.0001) but had weaker correlations with lineage plastic factors ( EZH2 , SOX2 , ASCL1 ) (R=0.26, 0.11, -0.02). Further, B7-H3-high correlated with high AR-score and low-NEPC. Given emergent bi-specific therapeutics in PC, we examined co-expression of B7-H3 with other cell surface targets. TROP2 ( TACSTD2 ) and NECTIN-4 ( PVRL4 ) exhibited the greatest correlation with B7-H3 (R=0.42, 0.40; q<0.0001); whereas PD-L1 ( CD274 ), CTLA4 , DLL3 , and CEACAM5 had weaker correlations (R=0.18, 0.08, 0.14, 0.09). Conclusions: High B7-H3 expression worsens prognosis in HSPC but improved prognosis in CRPC. Outcomes differed by race, with B7-H3-high Asian patients exhibiting worse OS while AA patients had better OS. The positive correlation between B7-H3 and AR co-factors suggests that B7-H3 is AR-regulated, at least in CRPC. Lastly, bi-specific approaches may be valuable against B7-H3-high tumors, with co-targeting of TROP2 and/or NECTIN-4.

4568 Background: The 2IR immune response score was initially developed using bulk RNA sequencing of pre-treatment tissue from ImVigor 210 and CheckMate 275 trials, however these trials enrolled patients (pts) with pure urothelial carcinoma (pUC) histology. Patients with hsUC often exhibit worse response to immune checkpoint inibitors (ICI) than patients with pUC. Here, we evaluated the 2IR score as a prognostic or predictive biomarker in real-world pts with hsUC. Methods: Specimens from pts with pUC (n = 1677) and hsUC (n = 417) were profiled at Caris Life Sciences (Phoenix, AZ) using next generation sequencing (NGS) of DNA and RNA. HsUC histologies included majority ( > 50%) squamous (n = 340), sarcomatoid (n = 51), neuroendocrine (n = 20), and micropapillary (n = 6) component. 2IR was calculated by comparative RNA expression of 10 adaptive immune genes and 39 pro-tumorigenic genes. Tumors were classified as 2IR-Low (2IR ≤ -0.5), -Mid (-0.5 < 2IR < 0), and -High (2IR ≥ 0), as previously described (Wang et al., 2022). Spearman correlation analysis was utilized to compare 2IR with tumor mutation burden (TMB), interferon score (IFN) and the tumor microenvironment (TME) cell fractions estimated using quanTIseq. Clinical outcomes included real-world overall survival (rwOS) from ICI start to last contact and time on treatment (ToT) with pembrolizumab, obtained via matched insurance claims data and calculated using Kaplan-Meier methods, while Hazard ratio (HR) was calculated by Cox proportional model. Results: For patients with hsUC, distribution of 2IR score was High 5.76%, Mid 33.3%, and Low 60.9%. Median 2IR score was significantly lower in squamous (-0.60, p < 0.0001) and sarcomatoid UC (-0.82, p < 0.0001) compared to pUC (-0.41) and significantly higher in neuroendocrine UC (-0.15, p = 0.003). Among patients with hsUC, median rwOS was significantly longer for patients with high/mid 2IR score compared to low 2IR score (25.3 [10.9-39.3] months vs. 8.7 [6.2-11.3] months; HR 0.52, 95% CI 0.34 – 0.78, p = 0.0017). ToT with pembrolizumab was also significantly longer for high/mid 2IR score compared to low 2IR score (3.0 [1.4-5.5] months vs. 2.1 [1.4-3.3] months; HR 0.68, 95% CI 0.46-1.00, p = 0.0471). Similar to pUC, 2IR score in patients with squamous UC was positively associated with CD8 T cell infiltration (r = 0.39; p < 0.0001), IFN score (r = 0.41, p < 0.0001), and TMB (r = 0.20, p < 0.001) and negatively associated with M1 macrophage infiltration (r = -0.25, p < 0.0001). 2IR scores in hsUC correlated positively but not significantly with mutations in TP53 (Median: -0.59 vs -0.62, p = 0.067) and PIK3CA (Median: -0.56 vs -0.61, p = 0.172) and negatively with mutations in CDKN2A (Median: -0.67 vs -0.59, p = 0.052). Conclusions: In a real-world cohort of patients with hsUC, we show the 2IR score may be prognostic for rwOS and predictive for pembrolizumab ToT. Prospective studies are needed to further validate this biomarker for use in this population.

Abstract Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare, aggressive lung tumor marked by significant molecular heterogeneity. In a study of 590 patients across two independent cohorts, we observed comparable overall survival across treatment regimens (chemotherapy, chemoimmunotherapy, immunotherapy) without unexpected adverse events. Genomic analysis identified distinct NSCLC-like (KEAP1, KRAS, STK11 mutations) and SCLC-like (RB1, TP53 mutations) LCNEC subtypes, with 80% aligning with SCLC transcriptional profiles. Serial sampling revealed stable mutational but shifting transcriptomic landscapes over time. NSCLC-like LCNECs showed elevated FGL-1 (a LAG-3 ligand) and SPINK1 expression, while SCLC-like subtypes expressed higher levels of DLL3. Immunofluorescence confirmed FGL-1 in NSCLC-like LCNECs, and H&E slide analyses indicated fewer tumor-infiltrating lymphocytes in LCNECs versus other lung cancers. These findings highlight LCNEC’s distinct immunogenomic profile, supporting future investigations into LAG-3, SPINK1, and DLL3-targeted therapies.

Abstract Purpose: Around 10% to 15% of prostate cancers harbor recurrent aberrations in the Forkhead Box A1 gene, FOXA1, whereby the alteration type and the effect on the forkhead (FKH) domain affect protein function. We developed a FOXA1 classification system to inform clinical management. Experimental Design: A total of 5,014 prostate cancer samples were examined using whole-exome and -transcriptome sequencing from the Caris Life Sciences database. We denoted class 1 FOXA1 alterations as missense and in-frame insertions/deletions with subclasses oriented with respect to the FKH domain. These were in the first part of the FKH domain [class 1A: amino acids (AA) 168–246], within the Wing2 region of FKH (class 1B: AA 247–269), or outside FKH (class 1C: AA 1–167, 270+). Two hotspot missense mutations at R219 were denoted class 2. Class 3 included predicted truncating mutations with subclasses partitioned based on the FKH domain (class 3A: AA 1–269 and class 3B: AA 270+). Class 4 represented FOXA1 amplifications. Real-world overall survival and therapy outcomes were determined from insurance claims. Results: FOXA1 alterations did not influence survival when considered in aggregate but had distinct prognostic effects when stratified by class. In primary prostate samples, class 1A alterations were associated with overall improved survival (HR, 0.57; P = 0.03); a similar trend was seen in metastatic biopsies with class 1B (HR, 0.84; P = 0.09). Conversely, in primary specimens, class 1C exhibited worse survival upon second-generation androgen receptor signaling inhibitor treatment (HR, 1.93; P &lt; 0.001). Class 2 mutations (R219C/S) were enriched in neuroendocrine prostate cancers and were associated with overall poor survival (HR, 2.05; P &lt; 0.001) and worse outcomes to first-line androgen-deprivation therapies (HR, 2.5; P &lt; 0.001). Class 3A alterations indicated improved survival (HR, 0.70; P = 0.01), whereas class 3B alterations portended poor outcomes (HR, 1.50; P &lt; 0.001). Amplifications (class 4) indicated poor outcomes in metastatic samples (HR, 1.48; P = 0.02). Molecularly, different FOXA1 alteration classes harbored distinct mutational and immunologic features as well as unique transcriptional programs. Finally, relative to European Americans, African Americans had increased class 1C alterations, whereas Asian/Pacific Islander patients had increased class 1B alterations. Conclusions: FOXA1 alterations should not be interpreted in aggregate, as different classes are associated with divergent molecular features and clinical outcomes. Our revised classification schema facilitates clinical decision-making for patients with prostate cancer and uncovers important racial differences.

Abstract B7-H3 (CD276) is a transmembrane glycoprotein of the B7 immune checkpoint superfamily that has emerged as a promising therapeutic target. To better understand the applicability of B7-H3–directed therapies, we analyzed 156,791 samples comprising 50 cancer types to interrogate the clinical, genomic, transcriptomic, and immunologic correlates of B7-H3 mRNA expression. DNA (592-gene/whole-exome) and RNA (whole-transcriptome) sequencing was performed from samples submitted to Caris Life Sciences. B7-H3 high versus low expression was based on top and bottom quartiles for each cancer type. Patients’ overall survival was determined from insurance claims data. Pathway analysis was performed using gene set enrichment analyses. Immune cell fractions were inferred using quanTIseq. B7-H3 is expressed across several human malignancies including prostate, pancreatic, ovarian, and lung cancers. High B7-H3 expression is associated with differences in overall survival, possibly indicating a prognostic role of B7-H3 for some cancers. When examining molecular features across all cancer types, we did not identify recurrent associations between B7-H3 expression and genetic alterations in TP53, RB1, and KRAS. However, we find consistent enrichment of epithelial-to-mesenchymal transition, Wnt, TGFβ, and Notch signaling pathways. In addition, tumors with high B7-H3 expression are associated with greater proportions of M1 macrophages, but lower fractions of CD8+ T cells. We have begun to define the genomic, transcriptomic, clinical, and immunologic features associated with B7-H3 expression in 50 cancer types. We report novel clinical and molecular features of B7-H3–high tumors which may inform how current B7-H3 therapeutics should be deployed and prioritized. Significance: B7-H3–targeting therapeutics have shown promising results in initial clinical trials. In this pan-cancer analysis of B7-H3 mRNA expression, we found that B7-H3 exhibits robust expression in many common cancer types. These results may inform further development of B7-H3–targeting therapeutics and may guide clinical decisions for patients with limited treatment options.