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Summary The authors of a recent study identified noncanonical peptides (NCP) presented by cancer cells’ HLA and observed lack of reactivity to these antigens by endogenous tumor-reactive T cells. In vitro sensitization generated NCP-reactive T cells that recognized epitopes shared by a majority of cancers tested, providing opportunities for novel therapies to shared antigens. See related article by Lozano-Rabella et al., p. xxx

Background: Glucocorticoid-Induced Tumor Necrosis Factor Receptor-related protein (GITR) is a co-stimulatory pathway that when triggered has potent effects on T-cell memory, proliferation and anti-tumor activity. Preclinical models identified significant synergy between anti-GITR agonist therapy and cancer vaccines to generate stronger tumor specific CD8 T cell responses. DPV-001 is an “off-the-shelf” multivalent autophagosome vaccine generated by in vitro manipulation of the autophagy pathway in human cancer cell lines. The vaccine delivers short-lived proteins (SLiPs) and defective ribosomal products (DRiPs) which are likely the dominant epitopes directly presented by MHC class I of tumor cells; but because of proteosomal degradation, are normally unavailable for cross-presentation, hence the delivery via vaccine. We hypothesize that addition of aGITR to DPV-001 vaccine will augment expansion of reactive CD4 and CD8 T cells, attenuate contraction of this response, and improve the therapeutic effect of treatment, and will result in the development of a coordinated T and B cell response to some of the same proteins, detectable using a cutting-edge seromics approach, as a window to TCR target identification for immunodynamic tracking of induced anti-cancer responses at an advanced level. Methods: Patient recruitment began in August 2022, for this first-in-human immunotherapy-trio study of DPV-001, with sequenced checkpoint inhibition (aPD-1 mAb; retifanlimab), with or without aGITR agonist mAb (INCAGN-1949), in recurrent or metastatic HNSCC (NCT04470024). Patient population to include HPV-positive or HPV-negative, ECOG 0-2, with therapy continued until confirmed progression (RECIST 1.1), up to 2 years. Primary objective is safety, DLT ≤ 33%, with secondary efficacy objectives of ORR (PR+CR) and 2 year OS. Initial safety lead-in (n = 3+3 per arm), will be followed by phase Ib expansion of one/both arms if immunologically promising, 28 patients per arm, futility if Study Drugs Cyclophosphamide 300mg/m2 IV, priming Day (-2) onlyVaccine (DPV-001)- Day 1 intranodal US bilateral inguinal- Days 8,15 intradermal, then q2wks to week 22- Thereafter q4wks until progression, up to 2 yearsaPD-1 (retifanlimab) 500mg IV q4wks, start Day 15 (Arms 1 & 2)aGITR (INCAGN01876) 300mg IV q2wks, start Day 1 (Arm 2 only) Response (RECIST 1.1) CT weeks 8 and 12, then q3mos Immunologic Monitoring PBL and sera are collected regularly and PBL are evaluated by flow cytometry. Biopsies obtained at baseline, Day 15 and Day 57, analyzed by mIF and 10x scRNA-Seq. Sera analyzed by phage immunoprecipitation (PhIP) sequencing for reactivity against the human proteome. Immune monitoring modifications that allow for improved characterization of immune cell subsets will be presented. Citation Format: Marcus A. Couey, Matthew Taylor, Tarsem Moudgil, Yoshinobu Koguchi, Anne Stadum, Tanisha Christie, William L. Redmond, Christopher Paustian, Ryan Meng, Venkatesh Rajamanickam, Lessli Rushforth, Abigail Peterson, Brady Bernard, Richard B. Bell, Carlo B. Bifulco, Traci L. Hilton, Shawn M. Jensen, Hong-Ming Hu, Brian Piening, Walter J. Urba, Bernard A. Fox, Rom S. Leidner. Trial in progress: First-in-human immunotherapy-trio for advanced head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT123.

Single cell RNA-seq (scRNA-seq) performed on cell suspensions isolated from tumor biopsies provides substantial insights into the transcriptional state of the cells in the tumor microenvironment (TME). Complementing this work with multi-omic Cellular Indexing of Transcriptomes and Epitopes (CITE-seq), which adds barcoded antibodies to label the surface of isolated cells, allows us to additionally characterize surface proteins. While information gleaned from these studies is dramatically expanding our understanding of the evolving immune response and tumor-immune interactions, it lacks an appreciation of the many spatial relationships that are present within the TME. Spatial phenotyping with the power of single cell resolution and whole slide imaging provides a valuable tool for identifying the cellular architecture and organization of spatial neighborhoods that perform critical roles in tumor progression, resistance, and clinical responses. Here, we explore bioinformatic strategies aimed at combining scRNA-seq and CITE-seq data with single-cell spatial protein data obtained with the PhenoCycler-Fusion (PCF) imaging platform. To this end, we performed whole-slide spatial phenotyping with an ultrahigh-plex PCF panel on FFPE human head and neck tumors. The same biopsies were also enzymatically digested and subjected to CITE-seq and scRNA-seq analysis. The combined multi-omic, single cell dataset provides a uniquely comprehensive account of the cellular states, functional significance and spatial neighborhoods that govern the TME. This study represents a novel approach to integrate high dimensional data from bulk tissue and single-cell spatial technologies to provide deeper insights into tumor biology and, in turn, to develop more informed strategies for combination immunotherapy trials and improved patient outcomes. Citation Format: Aditya Pratapa, Shawn M. Jensen, Niyati Jhaveri, Yoshinobu Koguchi, Venkatesh Rajamanickam, Brady Bernard, Tanisha Christie, Brian Piening, Rom S. Leidner, Oliver Braubach, Bernard A. Fox. Multi-parametric comparison of scRNA-seq with CITE-seq and ultrahigh-plex spatial phenotyping of proteins in FFPE head and neck tumor biopsies: An opportunity to generate uniquely comprehensive multi-omic single cell datasets to investigate the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6764.

Background: Preclinical studies document that complex cancer vaccines, combined with T cell agonists and anti-PD-1, can augment therapeutic efficacy. Here we report preliminary immunological analyses of patients enrolled in a first-in-human immunotherapy-trio study of multivalent autophagosome vaccine (DPV-001), with sequenced checkpoint inhibition (anti-PD-1; retifanlimab), with/without anti-GITR agonist (INCAGN-1949), in recurrent or metastatic HNSCC (NCT04470024). Methods: Peripheral blood (PB) and sera are collected regularly and PB are evaluated by flow cytometry. Biopsies obtained at baseline, D15 and D45 are analyzed by multiplex IF and 10x Genomics scRNA-Seq. Sera are being analyzed by phage immunoprecipitation (PhIP) sequencing for reactivity against the human proteome. Results: Preliminary results document increases in activated CD4 and CD8 effector memory T cells (TEM) with vaccine alone. Changes in tumor microenvironment (TEM) were also observed with increased infiltration of immune cells. Evaluation of changes to humoral immunity, T cell function and TCR analyses are ongoing. Conclusions: We previously reported immunological monitoring of a phase I/II trial of an autophagosome cancer vaccine (DPV-001) containing more than 300 shared cancer antigens, as adjuvant therapy for NSCLC. Vaccination induced or augmented immune responses to more than 50 cancer antigens shared with head and neck squamous cell carcinoma (HNSCC). Preclinical studies combining this cancer vaccine with αGITR agonist and αPD-1 augmented therapeutic efficacy [PMID: 31747946], and provided the rationale for the current study. This is the first clinical trial to perform such a study with αGITR agonist (INCAGN-1949), in humans. Support: Incyte, Providence Medical Foundation, The Harder Family, Nancy Lematta. Citation Format: Rom S. Leidner, Matthew H. Taylor, Tarsem L. Moudgil, Tanisha L. Christie, Yoshinobu Koguchi, Alexa Dowdell, William L. Redmond, Shawn M. Jensen, Carmen Ballesteros-Merino, Jake A. Vancampen, Venkatesh Rajamanickam, Brady M. Bernard, Christopher Paustian, Traci L. Hilton, Hong-Ming Hu, Richard B. Bell, Walter J. Urba, Carlo B. Bifulco, Brian Piening, Bernard A. Fox. Preliminary immunological monitoring of first-in-human immunotherapy-trio for advanced head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT502.

6043 Background: TAPUR is a phase II basket study evaluating anti-tumor activity of commercially available targeted agents in pts with advanced cancers with genomic alterations. Results in a cohort of HNC pts with CDKN2A loss or mutation treated with P are reported. Methods: Eligible pts had advanced HNC, no standard treatment options, measurable disease, ECOG PS 0-2, and adequate organ function. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Pts received P at 125 mg orally once daily for 21 days, followed by 7 days off until disease progression. Pts matched to P had CDKN2A loss or mutation and no RB mutations. Simon 2-stage design tested the null disease control (DC) - defined as partial (PR), complete response (CR) or stable disease at 16+ weeks (SD 16+) - rate of 15% vs. 35% (power = 0.85; α = 0.10). If ≥2 of 10 pts in stage 1 have DC, 18 more pts are enrolled. If ≥7 of 28 pts have DC, the null DC rate is rejected. Secondary endpoints are progression-free survival (PFS), overall survival (OS) and safety. Results: 28 pts (64% male) with HNC with CDKN2A loss (20 pts) or mutation (8 pts) were enrolled from June 2016 to Sept 2019. All were eligible for efficacy and toxicity. Demographics and outcomes are summarized in Table. No objective response (OR) and 10 pts with SD16+ (9 with CDKN2A loss, 1 with mutation) were observed for a DC rate of 37% (95% CI: 21%, 50%); the null DC rate of 15% was rejected (p=0.005). 14 pts had at least one grade 3-5 adverse or serious adverse event (AE/SAE) at least possibly related to P with the most common being low WBC/platelets. Other grade 3-4 AEs included anemia, fatigue, hypocalcemia, and syncope. There was one pt with grade 5 respiratory failure likely due to extensive lung metastases and aspiration but P-related pneumonitis could not be ruled out. Conclusions: Monotherapy P demonstrated modest anti-tumor activity and clinically significant AEs in heavily pre-treated pts with HNC with CDKN2A loss or mutation. Additional study is warranted to confirm the efficacy of P in pts with HNC with CDKN2A loss or mutation. Clinical trial information: NCT02693535. [Table: see text]