Obradović, Aleksandar

Abstract Background: Despite efficacy in metastatic clear cell renal cell carcinoma (ccRCC), immunotherapy currently has no role in the neoadjuvant setting. Suppressive tumor-associated macrophages (TAMs) are known to mediate resistance to immune checkpoint blockade (ICB) in ccRCC. In preclinical studies, IL-1β blockade reprograms TAMs toward an anti-tumor phenotype and promotes T cell activation, creating a tumor microenvironment (TME) more sensitive to ICB. To test this in patients, we conducted a correlative-rich neoadjuvant trial of IL-1β + PD-1 inhibition in localized ccRCC. Methods: SPARC-1 is a single-center, phase 1b study assessing the safety and feasibility of neoadjuvant canakinumab (αIL-1β) and spartalizumab (αPD-1) in patients with localized ccRCC (T1b-T4NanyM0 or TanyN1M0). All patients received 2 doses of canakinumab (300mg IV, Q4w) and spartalizumab (400mg IV, Q4w), 6 weeks (±7 days) prior to nephrectomy. The primary endpoint was safety and feasibility. Key secondary and exploratory endpoints included 12-month metastasis-free survival rate, pathologic response rate, and quantification of immune cell infiltration. To characterize immunologic reprogramming, fresh tumor specimens were collected at nephrectomy for single-cell RNA sequencing (scRNAseq) and multiparametric flow cytometry. Tissue from a treatment naïve cohort was collected for comparative analysis (n=16). Results: From August 15th, 2018, to January 30th, 2025, 14 patients were enrolled. There were no severe treatment-related adverse events (Grade ≥ 3) attributed to canakinumab or spartalizumab. At a median follow-up of 12.0 months (range, 6.3-12.0 months), the 12-month metastasis-free survival was 100%. Based on the ASSURE nomogram, the mean predicted 12-month recurrence risk was 16.7% (range, 4.7-46.5%). ScRNAseq revealed that treatment with αIL-1β + αPD-1 increased the frequency of TREM2+APOE+ TAMs (p=0.035), a population typically associated with immune suppression. However, these TAMs exhibited a phenotypic shift toward a less immunosuppressive state, with reduced IL-1β expression and increased CXCL9:SPP1 ratio, consistent with anti-tumor TAM polarization. Immune profiling revealed an increased CD8/CD4 T cell ratio (p=0.042) with modest enrichment of activated CD8+ T cells after treatment, supporting a more pro-inflammatory TME. Conclusions: The neoadjuvant combination of canakinumab (αIL-1β) and spartalizumab (αPD-1) is well-tolerated, feasible, and demonstrated promising clinical activity with no progression of disease observed in a localized ccRCC population at high risk of recurrence. Correlative analyses demonstrated that combined IL-1β and PD-1 blockade reprograms immunosuppressive TAMs, providing evidence that dual IL-1β and PD-1 inhibition can overcome myeloid-driven resistance in ccRCC. Clinical Trial Information: NCT04028245 Citation Format: Patrick J. McCann, Aleksandar Obradovic, Casey R. Ager, David H. Aggen, Catherine S. Spina, Chelsea L. Rahiman, Kaitlyn R. Campbell, Caroline Laplaca, Peyton C. Johnston, Amanda Kim, Katherine Gomez, Kriti Bagri Manjrekar, Mark N. Stein, Charles G. Drake, Karie Runcie, Matthew Dallos. Neoadjuvant IL-1β and PD-1 inhibition in localized clear-cell renal cell carcinoma: Clinical and correlative analyses of the phase 1b SPARC-1 trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr CT017.

Abstract Prostate cancer requires continual escape from immune surveillance, but mechanisms underlying this escape in the transition from androgen sensitivity to resistance and metastasis remain incompletely understood. Androgen-deprivation therapy (ADT)—the treatment backbone—induces tumor cell apoptosis but also remodels the tumor microenvironment (TME). We have assembled a single-cell RNA-seq atlas from >800,000 cells across 68 patients treated at Columbia University and Memorial Sloan Kettering. The resource includes 33 primary tumors (16 treatment-naïve, 17 post-ADT) annotated with time to PSA recurrence, and 31 metastases, including longitudinal pre- and post-ADT data in 14 castration-sensitive tumors (CSPC), 17 castration-resistant tumors (CRPC), and 4 neuroendocrine tumors (NEPC). This dataset spans the spectrum of prostate cancer disease progression.Using ARACNe and VIPER to infer activity of transcriptional regulatory and signaling proteins, we detect conserved cell state programs while minimizing batch effects. Several significant features emerged. Immune infiltration—both lymphoid and myeloid—is significantly higher in CSPC metastases than in primary or CRPC tumors and increases further after ADT. T cells constitute ∼15% of cells in primary tumors versus 30% in treatment-naive CSPC (40% post-ADT), falling to 13% in CRPC and <1% in NEPC (p<1e-32), consistent with an initially "hot" CSPC TME that progressively excludes T cells with disease progression.Among ∼350,000 epithelial/tumor cells, trajectory analysis reveals two differentiation pathways from normal epithelium. Pathway 1—dominant in primary tumors—shows androgen receptor (AR) activity with three sub-phenotypes (T1-T3): T1 exclusive to primary tumors; T2 shared by primary and CSPC; and T3 restricted to CRPC, with high ERG expression, and very strong AR activity. Pathway 2 (clusters T4-T6), present in NEPC and a subset of CRPC, lacks AR activity and displays SOX2, FOXA2, PRKD1. These aggressive states uniformly overexpress AURKA, RET, and TOP2A, suggesting druggable targets for combination therapy.We further define five cancer-associated fibroblast (CAF) subtypes. CAF1-3 track with advanced, treatment-resistant disease—enriched in NEPC versus CRPC (25% vs 18% of CAFs) and in CRPC versus CSPC (18% vs 11%)—while CAF4-5 predominate in primary tumors. We identify druggable proteins and receptor-ligand interactions linking CAF1-3 with T4-T6 tumor states; in vivo perturbations are underway.This atlas provides a resource profiling tumor and immune ecosystems across prostate cancer progression. It highlights MR programs and stromal-tumor-immune interactions that underlie immune evasion and ADT resistance, yielding actionable targets and combination-therapy hypotheses for aggressive disease. Citation Format: Aleksandar Obradovic, Kwangmin Yoo, Chang Liu, Patrick McCann, Casey R. Ager, Matthew C. Dallos, Samir Zaidi. Comprehensive profiling of primary and metastatic prostate tumors reveals distinct tumor and fibroblast cell states associated with androgen resistance [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 7419.

Abstract Background: Men with high-risk localized prostate cancer are at significant risk for disease recurrence and there is currently no role for neoadjuvant therapy. Although androgen deprivation therapy (ADT) is immunomodulatory and can increase CD8 T cell infiltration, these effects are counterbalanced by the expansion of suppressive regulatory T cells (Tregs). We therefore designed a correlative-rich clinical trial for men with high-risk localized prostate cancer to test whether BMS-986218 - a novel afucosylated anti-CTLA-4 antibody optimized for antibody-dependent cell-mediated cytotoxicity (ADCC) - depletes Tregs and augments response to ADT. Methods: Neo-Red-P is a single-center, two-arm, open-label pilot study assessing degarelix (ADT) versus ADT + anti-CTLA-4-NF (BMS-986218) in patients with treatment naïve high-risk localized prostate cancer. Key eligibility criteria included histologically confirmed adenocarcinoma with Gleason sum of ≥4+3 and clinical stage T1c-T3bN0M0. All patients received degarelix (ADT; 240mg SQ) 2 weeks before radical prostatectomy (RP). Patients were randomized to Arm A (ADT only), or Arm B (ADT + BMS-986218 [20mg IV] 2 doses Q2w starting 3 weeks before RP). The primary endpoint was the safety and feasibility of neoadjuvant BMS-986218 in prostate cancer. Secondary endpoints included the pathologic complete response rate, rate of undetectable PSA at 12 months, PSA response rate (>50% decrease pre-RP), and time-to-PSA recurrence. Fresh tumor specimens were collected at RP for single-cell RNA-sequencing, cytometry by time-of-flight, next-generation sequencing, and multiplex immunofluorescence. A treatment naïve cohort of matching demographic and pathological characteristics was collected for comparative analysis (n=14). Results: Between February 26, 2020, and November 15, 2022, 24 patients were enrolled. Severe treatment-related adverse events (TRAE; Grade ≥ 3) were rare in both arms; 0% in the ADT alone arm and 4% in the combination arm, suggesting a tolerable safety profile with the addition of BMS-986218. In the combination arm, 54% of subjects achieved a 50% reduction in PSA versus 33% in the ADT alone arm. In the ADT alone arm, 80% of patients had an undetectable PSA at 12 months, with a median recurrence-free survival of 1.61 years (IQR: 1.50-1.99 years). In the combination group, 75% had an undetectable PSA at 12 months, with a median recurrence-free survival of 1.82 years (IQR: 0.89-2.07 years). The overall recurrence rate in patients treated with combination therapy was 25% (3 of 12 patients) versus 20% (2 of 10 patients) in the ADT alone arm. Correlative studies suggest that aCTLA4-NF mitigates ADT-induced Treg accumulation through enhanced Fc receptor activity and augmented CTL activation, indicating an enhanced anti-tumor response with combination therapy. Conclusions: The neoadjuvant combination of ADT + aCTLA-4-NF (BMS-986218) is feasible, well tolerated, and induces significant remodeling of the immune TME through enhanced Fc receptor and CTL activity. Rates of disease recurrence following surgery were low in this high-risk population, warranting further investigation of combination immuno-hormonal therapy in the neoadjuvant setting for high-risk prostate cancer. Clinical Trial Information: NCT04301414 Citation Format: Patrick J. McCann, Casey R. Ager, Aleksandar Z. Obradovic, Matthew G. Chaimowitz, Samuel Pan, Caroline J. Laplaca, Parin Shah, Renu K. Virk, Christopher B. Anderson, Catherine S. Spina, Karie D. Runcie, Mark N. Stein, Charles G. Drake, Matthew C. Dallos. Efficacy and immunological outcomes of non-fucosylated anti-CTLA-4 (BMS-986218) + degarelix acetate vs. degarelix acetate alone in men with high-risk localized prostate cancer (Neo-Red-P) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT137.

Current methods for biomarker discovery and target identification in immuno-oncology rely on static snapshots of tumor immunity. To thoroughly characterize the temporal nature of antitumor immune responses, we developed a 34-parameter spectral flow cytometry panel and performed high-throughput analyses in critical contexts. We leveraged two distinct preclinical models that recapitulate cancer immunoediting (NPK-C1) and immune checkpoint blockade (ICB) response (MC38), respectively, and profiled multiple relevant tissues at and around key inflection points of immune surveillance and escape and/or ICB response. Machine learning-driven data analysis revealed a pattern of KLRG1 expression that uniquely identified intratumoral effector CD4 T cell populations that constitutively associate with tumor burden across tumor models, and are lost in tumors undergoing regression in response to ICB. Similarly, a Helios-KLRG1+ subset of tumor-infiltrating regulatory T cells was associated with tumor progression from immune equilibrium to escape and was also lost in tumors responding to ICB. Validation studies confirmed KLRG1 signatures in human tumor-infiltrating CD4 T cells associate with disease progression in renal cancer. These findings nominate KLRG1+ CD4 T cell populations as subsets for further investigation in cancer immunity and demonstrate the utility of longitudinal spectral flow profiling as an engine of dynamic biomarker discovery.

Abstract Purpose: Intratumoral immunosuppression mediated by myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM) represents a potential mechanism of immune checkpoint inhibitor (ICI) resistance in solid tumors. By promoting TAM and MDSC infiltration, IL1β may drive adaptive and innate immune resistance in renal cell carcinoma (RCC) and in other tumor types. Experimental Design: Using the RENCA model of RCC, we evaluated clinically relevant combinations of anti-IL1β plus either anti-PD-1 or the multitargeted tyrosine kinase inhibitor (TKI), cabozantinib. We performed comprehensive immune profiling of established RENCA tumors via multiparameter flow cytometry, tumor cytokine profiling, and single-cell RNA sequencing (RNA-seq). Similar analyses were extended to the MC38 tumor model. Results: Analyses via multiparameter flow cytometry, tumor cytokine profiling, and single-cell RNA-seq showed that anti-IL1β reduces infiltration of polymorphonuclear MDSCs and TAMs. Combination treatment with anti-IL1β plus anti-PD-1 or cabozantinib showed increased antitumor activity that was associated with decreases in immunosuppressive MDSCs and increases in M1-like TAMs. Conclusions: Single-cell RNA-seq analyses show that IL1β blockade and ICI or TKI remodel the myeloid compartment through nonredundant, relatively T-cell–independent mechanisms. IL1β is an upstream mediator of adaptive myeloid resistance and represents a potential target for kidney cancer immunotherapy.