Citations

Background: Recurrent Clostridioides difficile infection (rCDI) occurs in up to 35% of patients with CDI, and further recurrence is common. Fecal microbiota, live-jslm (RBL) is safe and effective for preventing rCDI in adults following antibiotic treatment for rCDI when administered rectally. There is clinical interest in alternative routes of administration. Objectives: CDI-SCOPE assessed the safety and clinical effectiveness of RBL when administered via colonoscopy to adults with rCDI. Design: Single-arm, exploratory phase IIIb trial conducted at 12 sites in the United States. Methods: Eligible adults with rCDI received one administration of RBL consisting of one 150-mL dose of RBL, delivered via colonoscopy to the right side of the colon. The primary endpoint assessed RBL-related treatment-emergent adverse events (TEAEs) within 8 weeks of RBL administration or until confirmed treatment failure. Secondary endpoints included treatment success (absence of CDI recurrence for 8 weeks following RBL administration), physician experience administering RBL via colonoscopy, and physician perception of participant benefit. Results: Of 54 participants screened, 41 were enrolled and received RBL via colonoscopy; 39 participants completed the 8-week visit. Five TEAEs in four participants (9.8%) were assessed as related to RBL, all of which were gastrointestinal and mild in severity. Overall, 18 participants (43.9%) experienced 33 TEAEs within 8 weeks, most of which were of mild (25/33; 75.8%) or moderate (5/33; 15.2%) severity. No TEAEs led to intensive care unit admission or death. Overall, 39 participants (95.1%) experienced treatment success; 2 participants (4.9%) withdrew consent and had an indeterminate outcome. Among physicians, 90.2% of investigators indicated a “positive” or “very positive” experience administering RBL by colonoscopy. All physicians assessed participant benefit as “much” or “very much” improved. Conclusion: This single-arm study suggests RBL administered via colonoscopy is practical, safe, and effective for preventing CDI recurrence following antibiotic treatment in adults. Trial registration: ClinicalTrials.gov: NCT05831189.

Abstract Most disease-associated single-nucleotide polymorphisms (SNPs) identified by genome-wide association studies (GWASs) reside in noncoding regions. There is increasing evidence that they play regulatory roles through epigenetic mechanisms by altering local chromatin state, 3D chromatin structure, and looping interactions. We and others have identified 42 CLL risk loci from GWASs. At 12 risk loci located outside of gene promoters, we previously demonstrated that functional SNPs are highly enriched in enhancers and super-enhancers that mostly target BCL2 family genes and transcriptional regulators. However, the study was limited by using only public epigenomic data generated in lymphoblastoid cell lines (LCL) and normal immune related cell types. To gain a better understanding of how the functional SNPs alter local chromatin state and modulate target gene expression in CLL, we generated RNA-seq data (n=588) and transposase-accessible chromatin with sequencing (ATAC-seq) data (n=69) in CLL tumor B cells. We performed molecular quantitative trait loci (QTL) analysis with index and correlated SNPs (R2 0.5) at 41 risk loci (excluding the HLA locus). The analyses identified cis expression QTLs (eQTLs), within 1Mb of genes’ transcription start site, at 25 risk loci and chromatin accessibility QTLs (caQTLs, within peak) at 11 risk loci, with both eQTLs and caQTLs at 8 risk loci. We identified a total of 54 eGenes, for which the expression is affected by nearby SNPs within 1Mb, including 40 novel eGenes at 16 CLL risk loci not previously reported. Notably, based on publicly available chromosome interaction data from CLL, LCL, and normal B cells, for over 70% of the novel eGenes, their promoters showed looping interactions with the regions carrying the eQTLs. Further, 13 SNPs were identified as both caQTL and eQTL, with the associated novel eGenes including CD81 at 11p15.5, IPCEF1 at 6q25.2, as well as CXXC1 and MBD1 at 18q21.1. The result suggests that these SNPs play a role in altering chromatin accessibility contributed to gene expression variation. At 11p15.5 risk locus, SNP rs2651823 (A/G) represents a novel caQTL and eQTL. The alternative G allele is associated with increased chromatin accessibility and CD81 expression. Hi-C data from GM12878 and CD20+ B cells supported interaction between the open chromatin region carrying rs2651823 and CD81 promoter. CD81 facilitates the trafficking of CD19 to the surface of activated B cells, and CD81-null mice showed impaired immune response. In a mouse model, CD81 contributes to tumor progression and metastasis in Lewis lung carcinoma. In summary, our molecular QTL analysis revealed that functional SNPs, located in CLL risk loci, modulate chromatin accessibility and expression of downstream target genes that could impact CLL risk. Citation Format: Huihuang Yan, Zhiquan Wang, Mingma Hoel, Cristine Allmer, Chantal McCabe, Daniel O’Brien, Dennis Robinson, James Cerhan, Sameer Parikh, Esteban Braggio, Susan Slager. Molecular QTL analyses identify functional variants at inherited risk loci in chronic lymphocytic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2763.

Abstract Background: Chromosomal instability (CIN) is frequent in patients with metastatic castration-resistant prostate cancer (mCRPC) and determines taxane resistance. A circulating tumor cell (CTC) assay which morphologically identifies CTCs with CIN (CTC-CIN) from a single tube of whole blood could predict clinical outcomes in this population. We tested this hypothesis as a pre-planned, secondary outcome of the CARD trial, where patients with mCRPC progressing within a year of treatment with an androgen receptor pathway inhibitor (ARPI; enzalutamide or abiraterone acetate + prednisolone/prednisone) were randomized to treatment with cabazitaxel or the alternative ARPI. Methods: CTCs were isolated from blood samples obtained at baseline; cycle two, and end of treatment. The associations of baseline CTC and counts with imaging-based progression free survival (ibPFS), overall survival (OS), time to prostate-specific antigen (PSA) progression, RECIST 1.1 objective response rate (ORR), and PSA50 response rate (PRR) were assessed. Results: Of 255 patients randomized, CTC counts were acquired from 237 patients at screening, 213 patients at C2D1, and 166 patients at EOT. High baseline CTC counts were significantly associated with worse OS (median OS, 14.9 vs 9.8 months; univariate HR, 1.81; 95% CI, 1.30 - 2.51; p < 0.001). High baseline CTC-CIN counts were significantly associated with worse OS after adjustment for confounding variables (median OS, 15.3 vs 8.9 months; univariate HR, 2.16; 95% CI, 1.52 - 3.06; p < 0.001; multivariate HR, 1.56; 95% CI, 1.01 - 2.43; p = 0.047). Low CTC-CIN at baseline predicted ibPFS, ORR, and PRR benefit with cabazitaxel; conversely, high at baseline predicted no different ibPFS or OS outcomes with cabazitaxel or a second ARPI. Conclusions: This preplanned biomarker analysis of CARD confirmed that CTC-CIN counts are prognostic for OS and may be predictive of cabazitaxel benefit. (Funded by Sanofi and Epic Sciences; CARD ClinicalTrials.gov number, NCT02485691.) Citation Format: Ossian Longoria, Jan Rekowski, Santosh Gupta, Nick Beije, Klaus Pantel, Eleni Efstathiou, Cora Sternberg, Daniel Castellano, Karim Fizazi, Bertrand Tombal, Adam Sharp, Oliver Sartor, Sandrine Mace, Christine Geffriaud-Ricouard, Richard Wenstrup, Ronald de Wit, Johann de Bono. Morphological evaluation of chromosomal instability in circulating tumor cells and prediction of taxane resistance in metastatic prostate cancer: a prespecified sub-analysis of the CARD trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1145

Abstract Poly ADP ribose polymerase inhibitors (PARPi) are being investigated in combination with photon and proton radiotherapy in clinical trials of pediatric and adult malignancies. The precise mechanisms of PARPi radiosensitization, and whether differences in photon and proton-mediated relative efficacy exist, have not been fully elucidated. To study mechanisms of PARPi radiosensitization we investigated the effects of PARPi in combination with photons and two different ionizing densities of protons delivered at the entrance (ENT) or the Bragg peak (BP) of the profile (dose-averaged LET [LETd] 2.2 and 7.0 keV/µm, respectively) of a 76.8 MeV proton beam after observing an extreme tumor and normal tissue response in an 18-year-old female patient with high grade glioma treated veliparib and proton therapy in a Children’s Oncology Group clinical trial. BRCA1/2 wild-type hTERT RPE-1, U2OS, and MDA-MB-231 cells were hypersensitive to the combination of veliparib and proton BP, with enhanced relative biological effectiveness (RBE) at 2 Gy values of 1.7, 1.4, and 1.3, respectively. Similar findings were observed with talazoparib and olaparib, suggesting that PARP trapping efficiency was not a major influence on the proton BP RBE. Further, we did not observe differences in transcription replication conflict between the different proton ionizing densities. Unexpectedly, DNA fiber assays revealed more elongated replication fork tracks in PARPi treated cells 60 minutes after proton BP compared with proton ENT, indicative of accelerated replication fork progression. To assess gap formation in the vicinity of nascent DNA we treated cells with the ssDNA-specific S1 nuclease and found that the lengths of CldU-labeled tracks were significantly reduced in cells treated with the PARPi/proton BP combination, suggestive of greater gap formation at replication forks. We postulated that more ssDNA gaps were being converted to DSBs during replication as we further observed that PARPi/proton BP resulted in increased γH2AX foci at 4- and 24-hours after treatment. Consistent with increased DSB formation, a higher proportion of cells arrested in the G2/M phase of the cell cycle at 24 hours following PARPi/proton BP. Despite being arrested in G2/M when homologous recombination is active, there was a significant increase in 53BP1 and a decrease in RAD51 recruitment, indicative of upregulated repair by more error-prone non-homologous end-joining (NHEJ) repair pathway. The enhanced proton BP RBE in PARPi treated cells was abrogated upon knockdown of XRCC4, a critical component of NHEJ repair pathway, suggesting that toxic NHEJ may be contributing to the enhanced proton BP RBE. In conclusion, PARPi renders cells hypersensitive to high LET BP proton irradiation. Enhancing the LET in combination with PARPi warrants further investigation to overcome therapeutic resistance. Citation Format: Yiqun Han, Qin Zhou, Anna Olson, Cameron M. Callaghan, Bin Chen, Nicholas B. Remmes, Meng Xu Welliver, Zheming Wu, Daniel K. Ebner, Jake A. Kloeber, Zhenkun Lou, Robert W. Mutter. Poly ADP ribose polymerase inhibitors potentiate proton therapy end-of-range relative biological effective dose by increasing replication stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4689.

Abstract Background: Epidemiology studies have linked frequent consumption of well-done cooked red meat with aggressive prostate cancer (CaP) risk, whereas rare intake or consuming medium-cooked meat is not. Providing public information about the impact of well-done cooking and its potential role in CaP risk may foster the adoption of evidence-based lifestyle modification of meat consumption to lower CaP risk. This pilot study aimed to provide preliminary data on the occurrence of CaP and the pattern of consumption of cooked red beef among ethnically diverse males in the US. Methods: The proposed project is an exploratory study focused on the assessment of the consumption of various beef dishes among ethnically diverse males in the United States. The study included 408 ethnically diverse males from Florida, Georgia, and Texas. Participants were recruited primarily from partnering restaurants, pharmacies, barbershops and collaborating community businesses using QR codes on the study flyer. Participants completed the self-administered survey that captured demographics, as well as information on beef consumption patterns, including cooking methods, frequency and degree of cooking, and the occurrence of CaP. The data were analyzed using descriptive statistics (frequency and percentages) to summarize demographics and variables on beef dishes. Chi-square was employed to determine the relationship between beef consumption patterns, demographic variables, and CaP occurrence. Results: The study showed that about half (49.8%) of the participants were between ages 44-63 years and 34.2% were 30-43 years old. The participants were quite diverse, as 51.7%, 16.3%, 13.1%, 11.%, and 2.7% were African American, African immigrants, White, Caribbean immigrants, and Hispanics, respectively. Rural dwellers comprised 34.2%, 26.8% were suburban, and 35.7% lived in urban areas. Educational status showed that 22.7%, 27.8%, and 22.7% were completed high school, college graduates, and associate degrees. The beef consumption pattern shows that 23.6%, 33.3%, 40.1%, and 30.3% regularly had boiled, fried, grilled, and barbequed beef, respectively, but 63, 2% reported never eating boiled beef. Doneness preferences differed among participants; 26%, 43.9%, 49.3, and 45.1% preferred well-done, while 1.7%, 1.5%, 2..9%, and 2.7% preferred rare, and 9%, 14.5%, 17.4%, and 15.7% preferred medium boiled, fried, grilled, and barbeques beef, respectively. Only 4.4% of the participants reported being diagnosed with CaP in the past. The pattern of beef consumption, such as the degree of doneness, was found for boiled (p=0.045), fried (p<0.001), grilled (p<0.001), and barbequed (p<0.001) beef, as well as frequency of consumption of (p<0.001), fried (p<0.001), grilled (p=0.001), and barbequed (p<0.001) to be associated with CaP. Conclusion: Beef consumption pattern was found to be associated with the risk of CaP among participants. Citation Format: Opeyemi Oreoluwa Bolajoko, Daniel W. Lee, Catherine Adebukola Oladoyinbo, Ernie Kaninjing, Samuel O. Antwi, Dee M. Glaser-Boivin, Robert J. Turesky, Folakemi T. Odedina. Pattern of beef consumption and prostate cancer risk among males in the United States [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7112.

Abstract Introduction: Most people who die from prostate cancer are older than 75 years. However, prostate cancer diagnosed at younger ages is often more aggressive. While epidemiologic studies have examined the association between age and survival in patients with prostate cancer overall, the clinical drivers of this relationship in patients with advanced disease remain unclear. We leveraged the International Registry of Men with Advanced Prostate Cancer (IRONMAN, NCT03151629) to (1) quantify the association between age and overall survival and (2) explore whether this association is explained by treatments. Methods: We included 3, 734 patients enrolled from 15 countries with new diagnoses of metastatic hormone sensitive (mHSPC, N=2, 642) or castration resistant prostate cancer (CRPC, N=1, 092). Age at enrollment was categorized as <55, 55-59, 60-64 (reference), 65-69, 70-74, 75-79, 80-84, 85+ years. We computed age-specific death rates (95% confidence intervals [CIs]) by disease state (mHSPC, CRPC) at enrollment. To explore whether this relationship was explained by treatment, we fitted disease state-stratified Cox models and sequentially adjusted for (1) de novo metastatic status and country, and (2) baseline treatment (androgen deprivation therapy [ADT] alone, ADT + androgen receptor pathway inhibitors [ARPI], ADT + chemotherapy, ADT + ARPI + chemotherapy, other). Results: Over 5.5 years of follow-up (median: 3.2 years, IQR: 1.7, 4.8), 995 patients died from any cause. Younger patients were more likely to have de novo metastatic disease. Among those with mHSPC at enrollment, the age-specific death rates per 1, 000 person-years followed a J-shaped pattern: 80 (95% CI: 54, 117) in patients under 55 years, 58 (46, 74) in patients aged 60-64, 102 (78, 133) in patients aged 80-84, and 172 (125, 236) in patients aged 85 and older. The death rates among those with CRPC followed a similar pattern, albeit rates were higher in magnitude: 212 (95% CI: 140, 323) in patients under 55 years, 153 (115, 202) in patients aged 60-64, 200 (155, 258) in patients aged 80-84, and 204 (142, 291) in patients aged 85 and older. After adjusting for disease state, country, and the timing of diagnosis of metastases, death rates were substantially higher for ages 75-79 (HR 1.4; 95% CI 1.1, 1.7), 80-84 years (HR 1.6; 95% CI 1.2, 2.1), and 85 years and older (HR 2.0; 95% CI: 1.5, 2.7) compared to ages 60-64 years. Patients aged under 55 years had 1.4-fold higher death rates (95% CI: 1.0, 1.9) compared to those 60-64 years. After additionally adjusting for baseline treatment, overall survival remained worse for the older patients and the youngest age group with hazard ratios remaining meaningfully unchanged. Conclusion: Age at enrollment is associated with overall survival in people with advanced prostate cancer enrolled in IRONMAN in a J-shaped pattern. This relationship is not explained by differences in baseline treatment. Citation Format: Hannah E. Guard, Michelle O. Sodipo, Colleen B. McGrath, Anna Siefkas, Lauren E. Howard, Konrad H. Stopsack, Christopher M. Sauer, Robert Dreicer, Emilio Esteban, Hassan M. Dogo, Ademola Popoola, Charles Waihenya, Anders Bjartell, Kim N. Chi, Sebastien Hotte, Richard Cathomas, Deborah Enting, Scott Tagawa, Michael Ong, Michael Kolinsky, Vincent Khoo, Joaquin Mateo, Chidiebere N. Ogo, Rana R. McKay, Stefanie Fischer, Heather H. Cheng, Russell Szmulewitz, Young E. Whang, Anand Sharma, Frédéric Pouliot, Simon Crabb, Monica S. Chatwal, Miguel A. Climent, Raymond McDermott, Ian D. Davis, Camille Ragin, Folakemi T. Odedina, Simon Anderson, Simone Badal, Natalie Greaves, Karen A. Autio, Laurel Cannon, Alyssa Chan-Cuzydlo, Marie Grant, Travis Gerke, Hannah D. McManus, Philip W. Kantoff, Daniel J. George, Lorelei A. Mucci, IRONMAN investigator team. Disentangling the association between age and overall survival in an international cohort of patients with advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4935.

Abstract Despite the advent of novel targeted therapies with high overall response rates, chronic lymphocytic leukemia (CLL) is still largely incurable due to the development of resistance. The bone marrow microenvironment (BMME) plays an important role in the survival and drug resistance in CLL. BM stromal cells (BMSCs) are considered a key component of BMME. Our long-term goal is to gain further insights of BMSCs-CLL crosstalk influencing both survival and drug resistance in CLL. To understand the global biologic changes that occur in leukemic CLL cells when in contact with BMSCs, we assessed RNA-seq in paired CLL cells isolated from untreated blood and BM and in untreated patients’ CLL cells cultured alone or with BMSCs. CLL cells from blood/BM and cultured alone/with BMSCs were also examined by Immunoprecipitation (IP), Western blot (WB), untargeted metabolomics (LCMS+GCMS), and preclinical drug sensitivity assays. We detected only 13 upregulated genes that overlap between CLL cells from BM and cocultured with BMSCs (p&lt0.05, fold change &gt1.5). When we analyzed the expression of these 13 genes in CLL cells from a cohort of 162 untreated patients by RNA-seq, we found associations between 4 genes (PNP, C16orf54, MOB3A, CDK2AP2) and clinical outcomes including overall survival (OS), progression free survival (PFS), and time to first treatment (TTFT) [multivariable Cox proportional hazards models, p&lt0.05]. Of the 4 genes, purine nucleoside phosphorylase (PNP), an enzyme in the purine pathway, had the most significant association with OS, PFS, and TTFT. Metabolomic profiling indicated an increased level of purine pathway metabolites adenosine, adenine, inosine, and hypoxanthine in cocultured CLL cells. WB analysis showed variable baseline PNP protein expression with 2 cohorts: low /no (L) and high (H) PNP using CLL blood cells. An induction in PNP protein levels were noticed in CLL cells expressing only LPNP when cocultured. Given the association of HPNP with adverse clinical outcomes, we tested for L vs. HPNP cohorts drug sensitivity to known BTK inhibitors(is) or Bcl2is. Treatment of CLL cells from untreated patients with Bcl2is venetoclax, S55746, and LP-118 (Bcl2-Bclxli, Newave) showed increased sensitivity to the Bcl2/Bclxlis in HPNP but not in LPNP cells. In addition, BTKis showed no difference in drug sensitivity associated with CLL PNP levels. To explain this discrepancy, WB and IP analyses were conducted in L vs. HPNP leukemic cells for apoptotic profiles, where we found increased phosphorylated-Bcl2(S70) and an increased association of Bcl2 with Bax in LPNP-expressing CLL cells compared to HPNP. These findings support increased resistance to apoptosis afforded by inhibiting Bcl2 for LPNP vs. HPNP-expressing CLL cells. Our future goals are to continue to understand the prognostic significance of the 4 genes with adverse clinical outcomes and to investigate how best to exploit the peculiar, enhanced sensitivity to Bcl2/Bclxlis found in the HPNP CLL cells. Citation Format: Sutapa Sinha, Weiguo Han, Zhiquan Wang, Brianna M. Finke, Heather C. Darby, Kari G. Rabe, Susan L. Slager, Chantal E. McCabe, Daniel R. O'Brien, Sameer A. Parikh, Esteban Braggio, Yi Chen, Fenlai Tan, Stephen P. Anthony, Yu Chen, Bing Dai, Yue Shen, Neil E. Kay. CLL drug resistance- A multifaceted mechanism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4423.

Abstract Introduction: The standard of care for metastatic hormone-sensitive prostate cancer (mHSPC) has evolved with the expanded approval of androgen receptor pathway inhibitors (ARPIs) alongside androgen deprivation therapy (ADT). ADT alone has been shown to affect cognitive function. However, the cognitive impact of distinct treatment combinations remains unclear. We investigated the association between first-line systemic treatments and the trajectory of subjective cognitive function among mHSPC survivors in the International Registry for Men with Advanced Prostate Cancer (IRONMAN). Methods: This analysis included 2435 newly diagnosed mHSPC patients enrolled across 15 countries between July 2017 and August 2024. Treatments were reported by site personnel and physicians. For this analysis, we focused on first-line systemic treatment and classified treatment groups at enrollment as ADT monotherapy (referent), ADT + ARPIs, or ADT + chemotherapy. Subjective cognitive function was assessed via the EORTC QLQ-C30 Cognitive Function subscale, with patient-reported scores (range 0-100) collected at enrollment and every 3 months for up to 5 years; higher scores reflect better cognitive function. Associations were estimated using linear mixed effects models with clustering by study site and country to examine differences at enrollment and across trajectories of subjective cognitive function by first-line treatment, adjusting for demographic and clinical factors. Results: Median age at enrollment was 70 years, with a median follow-up of 1.7 years. 724 (30%) participants were treated with ADT monotherapy, 1317 (54%) with ADT + ARPIs, and 394 (16%) with ADT + chemotherapy. Mean cognitive function scores at enrollment were 85.4 (Standard Deviation [SD] 19.5) for participants treated with ADT monotherapy, 86.7 (SD 17.3) for ADT + ARPIs, and 86.7 (SD 18.0) for ADT + chemotherapy. Cognitive function scores decreased by -0.60 points (95% Confidence Interval [CI] -0.72, -0.48) per year among those treated with ADT monotherapy, with similar rates observed for those treated with ADT + chemotherapy. Participants treated with ADT + ARPIs had a slower decline in cognitive function, with scores decreasing by -0.36 points (95% CI -0.60, -0.08) per year. Conclusion: In this international cohort of mHSPC survivors, subjective cognitive function scores were generally high at enrollment but declined over time. There was no evidence of worse cognitive function in those treated with ADT + ARPIs nor ADT + chemotherapy over time compared to ADT monotherapy. Cognitive functioning is a key component of survivorship, and defining cognitive trajectories associated with first-line treatment can inform supportive interventions, patient treatment decision-making, and clinical guidelines. Citation Format: Michelle O. Sodipo, Alicia K. Morgans, Erica T. Warner, Emily M. Rencsok, Lauren E. Howard, Colleen B. McGrath, Anna Siefkas, Konrad H. Stopsack, Christopher Sauer, Robert Drecier, Emilio Esteban, Hassan M. Dogo, Ademola Popoola, Charles Waihenya, Anders Bjartell, Kim Chi, Sebastien Hotte, Richard Cathomas, Deborah Enting, Scott Tagawa, Michael Ong, David Lorente, Elisabeth Heath, Rana McKay, Stefanie Fischer, Heather H. Cheng, Young E. Whang, Frederic Pouliot, Simon Crabb, Monica Chatwal, Miguel A. Climent, Raymond McDermott, Ian D. Davis, Camille Ragin, Folakemi Odedina, Natalie Greaves, Simone Badal, Simon Anderson, Sharon Harrison, Karen Autio, Laurel Cannon, Marie Grant, Alyssa Chan-Cuzydlo, Travis Gerke, Hannah D. McManus, Philip W. Kantoff, Daniel George, Sebastien Haneuse, Lorelei A. Mucci, on behalf of the IRONMAN Registry. First-line therapies and subjective cognitive function trajectories among international metastatic hormone-sensitive prostate cancer survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3630.

Abstract Recent evidence has highlighted the critical requirement for “immune triads” of CD8+ T cells, CD4+ T cells and dendritic cells (DC) for tumor elimination in response to checkpoint inhibition (CPI) immunotherapy. However, the mechanistic underpinnings of this cross-talk are poorly understood. Immune triads are often located in peripherally-distributed DC-rich niches within the tumor stroma. We have hypothesized that stromal remodeling in response to tumor expansion generates homeostatic signals that trigger an adaptive immune response that may ultimately fail through effector exhaustion or apoptosis. In particular, stromal proteolysis of the large matrix proteoglycan versican (VCAN) has been associated with T-cell infiltration across multiple tumor types. The objective of this study was to interrogate a mechanistic link between stromal remodeling, immune triad formation and response to CPI. We used HALO image analysis to determine the spatial relationship of CD4+ and CD8+ T cells in a panel of 95 human non-small cell lung cancers. Each tumor was VCAN proteolysis-scored based on a binning system measuring staining intensity for a neoepitope exposed through site-specific VCAN proteolysis. Tumors displaying VCAN proteolysis intensity of zero (0) had an average of 0.122 CD8+ T cells located with 10um of a CD4+ T cell vs. 0.216 in tumors with any VCAN proteolysis (intensity 1, 2, 3 combined); p=0.04. Similar results were obtained when measuring proximity of CD4+ to CD8+ T cells (0.124 vs 0.223, p=0.02). These data demonstrate that remodeling stroma promotes CD4+:CD8+ crosstalk. Site-specific VCAN proteolysis releases a 441 N-terminal bioactive fragment, versikine. Versikine constitutes a classical “matrikine”, i.e., a bioactive matrix fragment possessing novel functions compared to its parent macromolecule. To determine the mechanisms by which versikine may promote immune triad niches, we generated several transplantable syngeneic tumor cell lines engineered to stably secrete versikine into the TME. One CPI-refractory tumor cell line (Lewis Lung Carcinoma, LLC) and two partially CPI-responsive transplantable tumor lines (CT26 and MC38 colorectal carcinoma) were extensively characterized through flow cytometry, spatial immunofluorescence and scRNAseq. Our results demonstrate that in all contexts, versikine results in expansion of Tfh-like CD4+ T cells expressing Cd40lg and Icos. This expansion is associated with specific patterns of CD8+ T cell exhaustion that will be discussed. Therapeutically, versikine reversed anti-PD-1 pathway refractoriness in the poorly-immunogenic LLC model and demonstrated superior synergy with CPI in the more immunogenic CT26 and MC38 models, leading to tumor eradication with resistance to tumor rechallenge. Our data bolster the mechanistic rationale for exploitation of stromal remodeling signals to promote CD4+T:CD8+T:DC cross-talk for enhanced CPI efficacy. Citation Format: Daniel Lagal, Duncan Hong, Athanasios Papadas, Alicia Gibbons, Yun Huang, Yaling Dou, Alexander Cicala, Elsa Molina, Kristina Matkowskyj, Dustin Deming, Fotis Asimakopoulos. Stromal remodeling promotes immune triad formation in the tumor microenvironment (TME) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2588.