Park, Sean S.

Introduction Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase involved in immune signaling and has been implicated in tumor-intrinsic resistance to DNA-damaging therapies. Although SYK activity has been associated with poor outcomes in triple-negative breast cancer (TNBC), its role in resistance to combined radiotherapy and immune checkpoint blockade remains unclear. Methods SYK expression and clinical relevance were assessed across multiple breast cancer cohorts, including radiotherapy-treated datasets. Integrated transcriptomic analyses were used to characterize SYK-associated immune states. The functional effects of pharmacologic SYK inhibition were evaluated using in vitro assays and an immunocompetent bilateral 4T1 tumor model in female BALB/c mice treated with radiotherapy and PD-1 blockade. Treatment-associated immune remodeling was assessed by flow cytometry and transcriptomic profiling. Results Across multiple cohorts, elevated SYK expression, particularly in TNBC, was associated with inferior clinical outcomes and immune dysregulation. Pharmacologic SYK inhibition enhanced tumor responses to radiotherapy and PD-1 blockade at both irradiated and distant tumor sites. These effects were accompanied by coordinated remodeling of the tumor immune microenvironment, including suppression of neutrophil-associated signatures and reductions in immunosuppressive myeloid populations, including M2-like macrophages and myeloid-derived suppressor cells. Discussion Pharmacologic SYK inhibition enhances responses to radiotherapy and PD-1 blockade in preclinical TNBC models and is accompanied by remodeling of the immunosuppressive myeloid compartment. These findings support further investigation of SYK-targeted strategies to improve responses to combined radiotherapy and immune checkpoint blockade.

Abstract Cellular senescence has been implicated in the pathophysiology of radiotherapy-associated bone loss. Based on our previous work, clearance of senescent cells using genetic and pharmacological tools alleviates the anomalies associated with radiation-associated bone deterioration. The pro-inflammatory senescence associated secretome referred to as senescence associated secretory phenotype (SASP), is a hallmark of cellular senescence. The modulation of SASP by senomorphic drugs, potentially can suppress the pro-inflammatory secretome of senescent cells, irrespective of the underlying senescence mechanism. In this study we tested a senomorphic drug, ruxolitinib, a Janus kinase inhibitor (JAKi), during acute and chronic radiotherapy related effects on the bone. Our clinical data indicate an early increase in several pro-inflammatory SASP proteins following radiotherapy of spinal metastasis in prostate cancer patients. Longitudinal assessment of SASP-related genes confirmed this acute elevation in several SASP markers in systemic circulation following irradiation of male mouse femurs. In studies done in male mice, following three preclinical radiotherapy regimens of 30Gy (5 x 6Gy), 60Gy (5 x 12Gy) and a single dose of 24Gy, suppression of SASP by JAKi was efficacious in suppressing radiation-induced bone damage. In comparison and as shown before, the senolytic combination of D+Q was also able to alleviate radiation-associated bone loss. Early and intermittent suppression of SASP using JAK inhibitors in male mice alleviated chronic bone deterioration, diminished telomere dysfunction, lowered senescence and SASP marker expression and reduced bone-marrow adiposity. Overall, our study shows that early targeting of SASP proteins could be a potential therapeutic to prevent radiotherapy-related chronic bone loss and risk of fractures.

Abstract Understanding how immune checkpoint inhibitors (ICIs) reshape human T-cell responses requires models that move beyond static transcriptomic snapshots and discrete cell-state classifications. Here, we present an integrative AI-enabled virtual cell framework that represents human CD8⁺ T-cell responses as dynamic and computable systems during ICI therapy. By integrating single-cell RNA sequencing with paired T-cell receptor sequencing within the C2S-scale foundation model, we construct a virtual representation of individual T cells, in which each cell is encoded by a unique functional identity that captures its transcriptional, signaling, and clonal characteristics. Using this framework, we identify a previously unrecognized dynamic latent effector state of CD8⁺ T cells characterized by intermediate expression of effector genes, distinct signaling activity, and ongoing clonal expansion. Across independent patient cohorts, the virtual cell model consistently indicates that ICI therapy mainly acts by unmasking pre-existing effector potential rather than inducing de novo effector differentiation. Notably, this latent effector population remains transcriptionally restrained despite active signaling and clonal expansion, revealing a hidden reservoir of antitumor immune capacity. More broadly, our study demonstrates how AI-enabled virtual cell modeling can reconstruct latent cellular states and their dynamic transitions from multidimensional single-cell data. By incorporating functional identity into virtual cell model, this framework uncovers biologically meaningful yet non-obvious T-cell effector program during cancer immunotherapy and provides a generalizable approach for studying immune dynamics in human disease.

Background The optimal management of biochemical recurrence (BCR) after radical prostatectomy (RP) remains controversial, particularly in the absence of clinical or radiographic evidence of disease. Salvage radiotherapy (SRT) remains standard of care, but it is unclear whether SRT benefits patients when modern imaging with a multiparametric magnetic resonance imaging (mpMRI) and prostate‐specific membrane antigen‐positron emission tomography/computed tomography (PSMA‐PET/CT) are negative for local recurrence. Retrospective data comparing SRT to observation for such patients is fraught with selection bias, underscoring the need for a prospective randomised controlled trial. Study Design and Methods The Biochemical Recurrence Irradiation or Observation (BRIO) is a randomised study under the DIVINE trial framework (NCT06378866) enrolling men with BCR (prostate‐specific antigen [PSA] level ≥0.2, up to 1.5 ng/mL) after RP with no radiographic evidence of recurrence on mpMRI and PSMA‐PET/CT. Major inclusion criteria include age ≥18 years, biochemically recurrent prostate cancer after RP with a PSA level between 0.2 and 1.5 ng/mL, and no local or metastatic recurrence on imaging. A total of 312 patients will be enrolled. Participants are randomised 1:1 to standard‐of‐care SRT followed by surveillance (Group A), or initial observation with subsequent image‐guided therapy at radiographic progression (Group B). Based on historical analysis, a total of 30 metastasis events provides 80% power to detect a significant improvement (hazard ratio 0.5 corresponding to a 5‐year metastasis‐free proportion of 80.7% in the control group and 89.8% in the experimental group with one‐sided type I error rate of 0.15). All participants undergo baseline blood collection to measure prostate cancer‐extracellular vesicles and cell‐free DNA for biomarker development. Participants are followed in a 16‐week cycle with serial PSA measurements, repeat imaging if PSA doubles, safety assessment, and patient‐reported outcomes. Endpoints The primary endpoint is distant recurrence‐free survival at 5‐years using a 12‐month landmark to mitigate bias arising from differing assessment schedules for patients receiving optional 6 months of androgen deprivation therapy. Key secondary outcomes include time to hormone therapy, quality of life measures, adverse effects, and novel blood and urine biomarkers. Conclusion The BRIO study will clarify the clinical benefit of immediate SRT vs observation with image‐guided intervention in mpMRI and PET‐negative BCR after RP.

Abstract Introduction: Liver cancer remains a leading cause of cancer mortality globally with limited treatment options for patients (pts) with unresectable hepatocellular carcinoma [HCC] and intrahepatic cholangiocarcinoma [iCCA][1,2,3,4]. We hypothesize that combining the intratumoral dendritic cell (DC) vaccination after external beam radiotherapy (EBRT) without (phase I) and with (phase II) systemic atezolizumab and bevacizumab (atezo/bev for HCC) would enhance tumor-specific immunity and improve clinical outcomes, and present preliminary results from our phase I/II trial (NCT03942328). Methods: Peripheral blood mononuclear cells (PBMCs) were collected at baseline (PRE), after radiation (EBRT), and after completion of DC without or with atezo/bev (POST). Single-cell RNA sequencing with TCR sequencing were analyzed using CellRanger v7.0.1, Immunopipe, Seurat v5.3.0, & Gene-set enrichment analysis (GSEA). Long EFS (EFS-L) is defined as >=12 months (mo) for phase I and >=18mo for phase II, and short EFS (EFS-S) below that. Results: Seventeen patients have been analyzed to date (Phase I: n=8 [4 HCC, 4 iCCA]; Phase II: n=9 HCC). 674,106 cells were sequenced (146,843 PRE; 168,838 EBRT; 114,437 POST). GSEA for EFS-L vs EFS-S were comparable at PRE, EBRT and POST between phase I and phase II. EFS-S was associated with enrichment of interferon alpha (IFNα; B naïve, monocytes, pDC, cDC2, NK, Treg, CD8 Tcm and Tem at PRE and POST; B intermediate, CD4 Tem and NK at EBRT) and reactive oxygen species (ROS; PRE: pDC, CD8 Tcm, Tem. EBRT: CD4 Tem. POST: CD8 T naïve Tem, CD4 Tcm & Tem, cDC2) pathways. In contrast, EFS-L was associated with enrichment of WNT-β-catenin (WNT; CD14 mono at EBRT & POST, B intermediate at EBRT), TGFb (PRE: NK; EBRT: B intermed, CD4 Tem; POST: monocytes, CD4 naïve & Tem, pDC, cDC2), and angiogenesis (EBRT: NK; POST: monocytes, cDC2) pathways. Interestingly, enrichment of protein secretion pathway in NK cells was associated with EFS-L, but among other cells were associated with EFS-S (PRE: CD16 mono, Treg; POST: CD16 mono, CD4 & D8 Tem). Compared to phase I, addition of atezo/bev in phase II pts was associated with a significant increase in Gini coefficient (p<0.0001), suggesting expansion of certain TCR clones, along with a trend for increased Gini coefficient from Pre to Post in both phase I and II. Conclusions: Preliminary analysis of this study combining EBRT with intratumoral DC vaccination +/- PD-L1/VEGF blockade identified distinct treatment-related changes in systemic cellular immune profiles. Enhanced TCR clonal diversity in phase II suggests added immunologic benefit from PD-L1/VEGF blockade. As accrual continues, integrated analyses will identify systemic immune correlates of clinical benefit and resistance to this multimodal immunotherapy approach. Citation Format: Melody Wu, Panwen Wang, Chen Wu, Ying Li, Christopher L. Hallemeier, Thomas D. Atwell, Nguyen H. Tran, Andre de Menezes Silva Corraes, Kevin Regan, Zuoyi Shao, Rayaan Kamal, Haidong Dong, Lewis R. Roberts, Sean Park, Yi Lin, Lionel Aurelien Kankeu Fonkoua. Radiation-dendritic cell combination therapy drives systemic cellular immune shifts in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3741.

Abstract Cellular senescence has been implicated in the pathophysiology of radiotherapy-related bone loss. Based on our previous work, clearance of senescent cells using genetic and pharmacological tools alleviates the anomalies associated with radiation-associated bone deterioration. The pro-inflammatory senescence associated secretome referred to as senescence associated secretory phenotype (SASP), is a hallmark of cellular senescence. The modulation of SASP by senomorphic drugs, potentially can suppress the pro-inflammatory secretome of senescent cells, irrespective of the underlying senescence mechanism. In this study we tested a senomorphic drug, ruxolitinib, a Janus kinase inhibitor (JAKi), during acute and chronic radiotherapy related effects on the bone. Our clinical data indicate an early increase in several pro-inflammatory SASP proteins following radiotherapy of spinal metastasis in prostate cancer patients. Longitudinal assessment of SASP-related genes confirmed this acute elevation in several SASP markers in systemic circulation following irradiation of mouse femurs. In a proof-of-concept study, following two preclinical radiotherapy regimens of cumulative doses of 30Gy (5 x 6Gy) and 60Gy (5 x 12Gy), a senomorphic approach of JAKi treatment was more effective in alleviating radiation-related bone loss compared to the senolytic cocktail of D+Q. Early and intermittent suppression of SASP using JAK inhibitors alleviated chronic bone deterioration, diminished telomere dysfunction, lowered senescence and SASP marker expression, reduced bone-marrow adiposity, and mitigated radiation related lymphatic impairment. Overall, our study shows that early targeting of SASP proteins could be a potential therapeutic to prevent radiotherapy-related chronic bone loss and risk of fractures. Lay Summary Radiotherapy as part of cancer treatment is correlated with an acute increase in senescent cells. Here we show that the pro-inflammatory senescence associated secretory phenotype (SASP) becomes much more prominent soon after radiotherapy in both patients and mice. Suppression of the SASP using a Janus kinase inhibitor, ruxolitinib, reduced the overall senescent cell burden, improved bone architecture by promoting bone formation, reduced bone marrow adiposity, and mitigated radiation-induced lymphatic impairment. Overall, these findings suggest that early inhibition of the SASP may help mitigate several bone anomalies and prevent long-term bone loss and fractures after radiotherapy. Graphical Abstract

Immunotherapy has been effective in many cancer types but has failed in multiple clinical trials in prostate cancers, with the underlying mechanisms remaining largely unclear. Here, we demonstrate that androgen receptor pathway inhibitor (ARPI) plus irradiation (IR) triggered robust anticancer immunity in prostate cancers in both patients and mice. We show that androgen-activated AR suppressed innate immune signaling by inducing inhibitor of nuclear factor kappa-B kinase subunit epsilon ( IKBKE ) gene repression through HDAC2 interaction with an IKBKE enhancer RNA ( IKBKE eRNA, or IKBKE-e ). ARPI treatment caused IKBKE derepression and enhanced an IR-induced innate immune response via action of RIG-I and MDA5 dsRNA sensors. IKBKE-e ablation largely enhanced innate immunity in prostate cancer cells in culture and anticancer immunity in mice. Our results revealed AR, HDAC2, and IKBKE eRNA as critical intrinsic immune suppressors in prostate cancer cells, suggesting that rejuvenating inhibitor of nuclear factor kappa-B kinase subunit epsilon (IKKε) signaling by targeting IKBKE-e is an actionable strategy to elicit synthetic anticancer immunity in immunologically “cold” cancers such as prostate cancer.

Abstract Background Partial breast irradiation (PBI) is an effective treatment for early-stage breast cancer. However, evidence comparing different PBI modalities is limited. Methods This trial emulation uses electronic health records from a multi-state large tertiary health system. Three PBI modalities were compared: proton radiation therapy, photon radiation therapy, and applicator-based brachytherapy. Inverse probability weighting (IPW) was used to balance confounders. The primary outcome was ipsilateral breast recurrence (IBR). Results Between 2013 and 2023, 1041 women with early-stage breast cancer were treated with PBI. Of these, 1026 patients were included in the analyses. The median age was 66 years; 22.51% had ductal carcinoma in situ (DCIS), and 97.56% were estrogen receptor positive. With median follow-up of 38.2 months, the rate of IBR in the overall group was 3.05% (95% confidence interval [CI] = 1.99% to 4.65%) at 3 years. After IPW, compared with photon PBI, the hazard ratio for IBR for proton PBI was 2.11 (95% CI = 0.70 to 6.33) and for brachytherapy, 3.86 (95% CI = 1.39 to 10.69). Compared with proton PBI, the hazard ratio for IBR for brachytherapy was 1.83 (95% CI = 0.88 to 3.81). IBR risk was similar across PBI modalities for patients with tumor size ≤ 10 mm and in patients treated for DCIS. Among patients with tumor size >10 mm, the hazard ratio for IBR for brachytherapy was 7.64 (95% CI = 1.64 to 35.58) and 3.59 (95% CI = 1.22 to 10.56) relative to photons and protons, respectively. Conclusion PBI with applicator-based brachytherapy was associated with higher IBR than photon or proton PBI in patients with tumor size > 10 mm, suggesting the need for more careful PBI patient selection for this modality.

Abstract Description Background Castration-resistant prostate cancers (CRPC) do not respond to immunotherapy.1,2 Prostate cancer-derived immune factors (IF) like sPD-L1 drive immunosuppression and resistance.3 Circulating tumor-reactive T cells (TTR; CD8+CD11ahigh) and other immune subsets predict progression-free survival in oligometastatic CRPC after radiotherapy.4 A better understanding of the levels and changes in IF in CRPC—a tumor immune “circulome”—may lead to better immunotherapeutic approaches. Methods 79 men with oligometastatic castration-resistant prostate cancer were treated with radiation and blood was collected before and after treatment (NCT02816983). Peripheral blood mononuclear cells (PBMC) were subjected to immunophenotyping, and plasma was subjected to the Olink Explore panel assay measuring levels of 5,416 IFs using a proximity extension assay technology. Results High baseline soluble levels of PD-L1, PD-L2, TIM-3, and other selected immunotherapy-related IFs predicted inferior outcomes, including overall survival. Conversely, high soluble CTLA-4 levels strongly predicted superior outcomes (p < 0.0001). These results additionally correlated with changes in circulating tumor-reactive (TTR) T cells in these patients. Discussion IF influence systemic immunity in CRPC. These results suggest a multifactorial mechanism by which prostate cancers drive systemic immunosuppression and resistance to immunotherapy. Ongoing efforts to address IFs may help overcome CRPC immunotherapy resistance.5 Funding Sources Department of Defense HT9425-24-1-0622, An Atlas of the Tumor Immune Circulome (PI: Orme) Prostate Cancer Foundation Young Investigator Award (PI: Orme) National Cancer Institute K12 CA90628-23 (PI: Orme) Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)