Citations

Immunosuppression within the tumor microenvironment (TME) poses a significant challenge to the efficacy of Chimeric Antigen Receptor (CAR) T-cell therapy in solid tumors, including glioblastoma (GBM), the most common and deadly primary brain tumor. Tumor and TME-residing immunosuppressive cells can hijack program death 1(PD1) pathway to evade antitumor T-cell immunity by upregulating its ligand, PD-L1. Thus, targeting PD-L1 emerges as a promising therapeutic strategy to simultaneously eliminate tumor cells and immunosuppressive components within the TME. We developed a novel PD-L1-targeting CAR T-cell therapy, MC9999, and investigated its therapeutic effects against GBM. The antigen-specific cytotoxicity of MC9999 CAR T-cells was firmly validated using a LN229 GBM cell line and its PD-L1-deficient variant, as well as patient-derived brain tumor-initiating cells (BTICs). Furthermore, in vivo therapeutic antitumor effects were confirmed in orthotopic GBM models through intracranial administration of MC9999 CAR T-cells. To pave the way to the translation of MC9999 CAR T-cell therapy to patient bedside, we established a unique experimental system using patient-specific CAR T-cells against their own tumor and immunosuppressive cells. High-quality, patient-specific MC9999 CAR T-cells were manufactured using T cells isolated from peripheral blood, while paired autologous BTICs were generated to serve as target cells. Autologous immunosuppressive cells include monocyte-derived M2 macrophages from patient’s peripheral blood and tumor-associated macrophages (TAMs) isolated from patient’s tumor. Data from multiple patients’ samples consistently demonstrated that these patient-specific MC9999 CAR T-cells elicited robust cytotoxicity against autologous GBM tumor and TME-residing immunosuppressive cells, supporting our hypothesis that targeting PD-L1 effectively address both tumor and its TME. Immunohistochemistry (IHC) staining of our GBM patients’ tissues showed that PD-L1 expression was restricted to tumor cells and macrophages /microglia within the tumor, with no expression detected in neurons, astrocytes, oligodendrocytes, or blood vessels. These findings suggest that MC9999 CAR T-cells can be safely delivered to the brain without compromising normal cell populations. Ongoing studies are underway to further validate the safety profile of MC9999 CAR T-cell therapy. Collectively, the data obtained from this preclinical study support the effectiveness, feasibility and safety of local administration of MC9999 CAR T-cells as a promising new approach for GBM treatment. These encouraging results have motivated us to prepare an Investigational New Drug application to initiate a phase I clinical trial. Citation Format: Yan Luo, Yaqing Qie, Maria J. Ulloa-Navas, Jesus E. Sanchez-Garavito, Vanessa K. Jones, Martha E. Gadd, Mieu M. Brooks, Tanya Hundal, Andrew D. Brim, Isas K. Vazquez-Rosario, Haidong Dong, Alfredo Quinones-Hinojosa, Hong Qin. Intracranial delivery of MC9999 CAR T-cell therapy: a novel strategy to simultaneously eliminate GBM tumors and immunosuppressive components in the tumor microenvironment [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 4812.

ABSTRACT The insulin‐like growth factor‐1 (IGF‐1) signaling pathway is known as a potent aging modifier, disruption of which consistently associates with lifespan extension across diverse species. Despite this established association, the mechanisms by which IGF‐1 signaling modulates organ aging remain poorly understood. In this study, we assessed age‐related changes in IGF‐1 expression across multiple organs in mice and identified a more prominent increase in skin IGF‐1 levels with aging—a phenomenon also observed in human skin. To explore the consequences of elevated IGF‐1, we developed transgenic mice ectopically expressing human IGF‐1 in the epidermis, driven by the bovine keratin 5 promoter (IGF‐1 Tg). These mice exhibited premature aging of hair follicles, as evidenced by accelerated hair graying and loss. Single‐cell RNA sequencing analyses of dorsal skin highlighted an upsurge in cellular senescence markers and the senescence‐associated secretory phenotype (SASP) in hair follicle stem cells (HFSCs), alongside a decline in hair growth and HFSC exhaustion. Our findings indicate that excessive IGF‐1 triggers HFSC senescence, thereby disrupting hair follicle homeostasis. Remarkably, interventions in IGF‐1 signaling via downstream mechanisms—specifically blocking Ac‐p53 activation via SIRT1 overexpression or senolytic treatment for senescent cell clearance, or reducing IGF‐1 through dietary restriction—significantly reduced senescence markers, mitigated premature hair follicle aging phenotypes, and restored the stem cell pool. Our findings provide fundamental insights into the biological processes of hair aging and highlight the therapeutic promise of targeted interventions to rejuvenate aged HFSCs and promote hair follicle health.

Extramedullary multiple myeloma (EMM), defined in this review as soft tissue plasmacytomas resulting from hematogenous spread, is characterized by the ability of MM cells to proliferate outside of the bone marrow microenvironment. It is aggressive, often associated with high-risk cytogenetics and early relapse, and independently portends significantly shorter progression-free and overall survival, even in the era of highly effective immunotherapies. The molecular and microenvironmental factors underlying extramedullary MM dissemination continue to be studied to inform the development of better treatments. In this review, we discuss our current understanding of the biology of EMM, focusing on its distinct molecular and microenvironmental characteristics vis-à-vis MM. We also review the current treatment strategies, acknowledging the paucity of large, randomized studies specific to this population.

Abstract Purpose: Germline alterations in homologous recombination repair (gHRR) genes affect the pathogenesis, treatment options, and survival of patients with cancer. However, distinct gHRR gene alterations may differentially affect treatment response and oncogenic signaling. In this study, we interrogated genomic and transcriptomic data and assessed clinical outcomes of patients with gHRR mutations across four BRCA-associated cancers (breast, ovarian, pancreatic, and prostate cancers) to identify therapeutic vulnerabilities. Experimental Design: We assessed 24,309 patients undergoing matched tumor/normal next-generation DNA and RNA sequencing. Annotated gHRR gene variants [germline BRCA1, germline BRCA2, germline PALB2, germline ATM (gATM), and germline CHEK2] were analyzed. HRs were used to assess survival outcomes comparing germline versus sporadic groups. Somatic alterations and their frequencies were compared across gHRR-altered groups. Differential gene expression and gene set enrichment analysis were used to compare transcriptomic profiles. Results: Somatic TP53 mutations were depleted in gATM carriers (P < 0.05) across all four BRCA-associated cancers by up to 2.5-fold. Tumors with germline BRCA1/2 mutations were associated with improved survival in patients with ovarian cancer and had consistent enrichment of TP53 mutations in all four cancers. gATM mutations displayed elevated p53 transcriptional activity in all four cancers, with significance reached in breast and prostate cancers (P < 0.01). In breast, ovarian, and prostate cancers, gATM tumors demonstrated significantly increased inflammatory pathways (P < 0.001). Finally, using gene dependency data, we found that cell lines that were highly dependent on ATM were co-dependent on canonical p53 function. Conclusions: gATM-associated cancers seem to require intact p53 activity and this synthetic essentiality may be used to guide targeted therapies that perturb canonical TP53 function.

428 Background: Prostate cancer management presents a significant healthcare burden, with the need to efficiently triage patients for treatment. Our objective is to leverage large language models to predict physician-recommended treatment plans from unstructured clinical notes. By accurately predicting treatment plans, we aim to risk stratify and triage patients effectively, thereby optimizing the allocation of physician resources. Methods: 448 unstructured initial urology consultation patient notes following first positive prostate cancer biopsy were identified. The recommended and final treatments received were manually annotated to establish ground truth labels (Table 1). The dataset was split 80:20 for training and testing, preprocessed to remove plan sections and formatted into question-answer (QA) format. A domain-specific large language model (LLM) inspired by GPT and a specialized tokenizer (PCa- LLM) for prostate cancer terminology were developed. QA models were built using the PCa-LLM and compared with those using GPT-2 as the backbone to predict recommended and final treatments. Results: For the physician-recommended treatment plans, our LLM (PCa-LLM) showed superior performance with higher AUROC scores for curative vs. non-curative treatments (0.78 vs. 0.65), chemo-hormonal vs. other non-curative treatments (0.89 vs. 0.65), and surveillance vs. all other treatments (0.72 vs. 0.70), while both models achieved the same high AUROC of 0.99 for chemo-hormonal vs. all other treatments. For final treatments, PCa-LLM demonstrated better AUROC for curative vs. non-curative treatments (0.77 vs. 0.74) and chemo-hormonal vs. other non-curative treatments (0.71 vs. 0.66), while GPT2 outperformed PCa-LLM for surveillance vs. all other treatments (0.78 vs. 0.70). Both models achieved an AUROC of 0.99 for chemo-hormonal vs. all other treatments. Conclusions: PCa-LLM accurately predicted most treatment categories better than GPT2, with higher AUROC scores, and can be utilized to triage prostate cancer patients using initial consultation notes. Task Physician -Recommended Treatment Plan Final Treatment Received Curative Prostatectomy/Radiation 228 230 Non-Curative Focal Therapy 22 15 Active Surveillance 40 45 Chemo-hormonal 30 30 Model Predictions (AUROC) GPT2 PCa-LLM GPT2 PCa-LLM Curative vs. non-curative 0.65 0.78 0.74 0.77 Chemohormonal vs. other non-curative 0.65 0.89 0.66 0.71 Chemohormonal vs. all other 0.99 0.99 0.99 0.99 Surveillance vs. other non-curative 0.64 0.60 0.67 0.59 Surveillance vs. all other 0.70 0.72 0.78 0.70

Abstract Background Histologic inflammation persists in up to 1/4 of patients with Crohn’s disease (CD) despite endoscopic mucosal healing. Histologic and combined endoscopic-histologic endpoints are evolving measures of treatment efficacy in CD; however, the impact of histologic healing on long-term outcomes and disease progression is unknown. Week (W) 52 data comparing mirikizumab (Miri) vs placebo (PBO) in the randomized, double-blind, placebo- and active-controlled, treat-through Phase 3 VIVID-1 trial in patients with moderately-to-severely active CD (NCT03926130) were reported previously.1 Methods The main objective was to evaluate the association of W12 histologic response and W12 histologic remission with W52 clinical and endoscopic outcomes in VIVID-1. Two biopsy specimens from each of 5 intestinal segments (1 ileal and 4 colonic) were obtained from the edge of the ulcers, or the most inflamed mucosa from randomized patients at screening, W12, and W52. All analyses were post hoc and among patients with active histologic disease (defined as a Robarts Histopathology Index >0 and a Global Histologic Disease Activity Score >0) at baseline. Results At W12, treatment with Miri resulted in statistically significantly higher rates of achieving histologic response and histologic remission vs. PBO (Figure). At W12, 62.1% of patients had agreement (k=0.27 [fair]) between histologic response and endoscopic response, with a greater percentage achieving histologic over endoscopic response (59.0% vs. 38.8%)*. Significantly greater proportions of patients who achieved histologic response at W12 also achieved histologic response, histologic remission, endoscopic response, endoscopic remission, combined CDAI (Crohn’s Disease Activity Index) remission and endoscopic response, and normalisation of faecal calprotectin levels ≤250 µg/g and ≤150 µg/g at W52 (Table). Similar associations were observed between W12 histologic remission and W52 outcomes. Conclusion Histologic response seems to be an early objective sign of anti-inflammatory response and was significantly associated with one-year endoscopic and histologic outcomes, as well as biomarker normalisation. *Observed data References 1.Jairath V, et al. Presented at: UEGW 2024. OP131.