Abstract: 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 & lt;4/15 responses. 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.

Abstract: 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.

Abstract: Background: Acute myeloid leukemia (AML) blast and leukemic stem cells highly express CD123, which is associated with high-risk disease and disease progression. CD123 expression on normal hematopoietic stem cells is minimal, enabling a strategy of preferential ablation of AML with a CD123-targeted approach. Flotetuzumab (MGD006/S80880) is a novel T-cell redirecting (CD123 x CD3) bispecific DART® protein being tested in a phase 1 study in patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Methods: This phase 1 dose-escalation study is designed to define the safety profile, maximum tolerated dose and schedule (MTDS), and preliminary anti-leukemic activity of flotetuzumab. Relapsed/refractory (R/R) AML or intermediate-2/high-risk MDS patients (pts) are treated on 28-day cycles at doses from 3-1000ng/kg/day on one of 2 dosing schedules (4-day on/3-day off or a continuous 7-day on schedule). To mitigate cytokine-release syndrome (CRS), a one-step lead-in dose (LID) (100ng/kg/day for 4 days) or two-step LID (30 ng/kg/day for 3 days followed by 100ng/kg/day for 4 days) was instituted during Cycle 1/Week 1 (C1W1), followed by the cohort target dose (300-1000ng/kg/day) on either of the dosing schedules on W2-4. Cycle 2 and beyond, all pts were treated on a 4-day on/3-day off schedule at the cohort target dose for a maximum of 12 cycles, with 2 cycles after a complete response or complete remission with incomplete blood count recovery. Steroid-sparing, anti-cytokine therapy was used, if clinically indicated, to manage CRS symptoms. Disease status was assessed by International Working Group (IWG) criteria. Samples were collected for pharmacokinetics, anti-drug antibodies (ADA) and cytokine analysis, including IL-2, IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma and GM-CSF. Results: 45 pts with R/R AML/MDS (89% AML and 11% MDS) have been treated with flotetuzumab, median age of 64 (29-84), and 44% female. The MTDS has been reached at 500ng/kg/day. Overall flotetuzumab has demonstrated manageable toxicity; drug-related adverse events ≥G3 were observed in 20/45 (44%) pts; infusion-related reaction/CRS (IRR/CRS), the most common toxicity, was observed in 34/45 (76%) pts (G3 in 6/45, 13%). The most frequent CRS symptoms were pyrexia (15), chills (10), tachycardia (10), and hypotension (4). Cytokine levels were higher in pts with CRS than in pts without (median IL-6, 116.2 vs. 67.9 pg/mL; IL-8, 191.1 vs. 144.6 pg/mL; IL-10, 867.6 vs. 348.7 pg/mL) and were generally higher with increasing CRS grade. A two-step LID during week 1 appeared to decrease the severity of CRS grade (mean grade reduction 0.54) compared to pts that received a one-step LID during cycle 1. In addition, lower median peak cytokine levels are observed with two-step LID during W1 and after achieving W2 target dose. Fourteen pts treated at the threshold 500 ng/kg/day dose cohort and beyond (700ng/kg/day dose cohort) have completed at least one cycle of treatment and had a post-treatment bone marrow (BM) biopsy. Anti-leukemic activity was documented in 57% (8/14) pts, 6/14 reached IWG criteria (3 CR, 1 CRi, 1 MLF, 1 PR) for an overall response rate (ORR) of 43%, and 2 pts had stable disease and bone marrow (BM) blast reduction of 20 and 25% from baseline, respectively. Blast reduction occurred rapidly, often within one cycle of therapy, and extended beyond flotetuzumab discontinuation. Multispectral immunohistochemistry analysis of BM samples showed flotetuzumab in situ with a significant increase (in CD-8 T cells (1.58-fold increase, p=0.0013). Consistent with T-cell activation, CD-25, CD-69 and PD-1 upregulation on both CD-4 and CD-8 T-cells was also observed in peripheral blood samples. Conclusions: Flotetuzumab in R/R AML and MDS demonstrated evidence of anti-leukemic activity (ORR 43%) with a manageable safety profile. This program advances an immune-activating agent in treating AML and continues to enroll patients in cohort expansion (24 AML and 24 MDS patients at the MTDS) in the US and Europe. clinicaltrials.gov NCT02152956. Disclosures Uy: Boehringer Ingelheim: Consultancy; GlycoMimetics: Consultancy; Novartis: Consultancy, Other: Travel Suppport. Foster: Macrogenics: Research Funding; Shire: Honoraria; Pfizer: Research Funding; Amgen: Honoraria; Incyte: Honoraria; Celgene: Research Funding; Celator: Research Funding. Arellano: Cephalon Oncology: Research Funding. Rizzieri: Shire: Research Funding; Erytech: Research Funding. Topp: Roche: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Research Funding; Macrogenics: Consultancy, Research Funding; Celgene: Other: Travel; Regeneron: Consultancy, Honoraria, Research Funding. Martinelli: Incyte, Pfizer, MSD, Abbvie, J & J, Seattle Genetics, Jazz Pharmaceuticals, Astellas: Consultancy, Other: Advisory Board, Speakers Bureau. Ciceri: GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding. Lelièvre: Institut de recherches international Servier: Employment. La Motte-Mohs: Sunnybrook Health Sciences Centre: Patents & Royalties; MacroGenics: Employment, Equity Ownership, Patents & Royalties. Sun: Macrogenics Inc: Employment, Equity Ownership. Baughman: MacroGenics, Inc.: Employment. Shannon: MacroGenics, Inc.: Employment. Fox: Bristol Myers-Squibb: Consultancy, Research Funding; AstraZeneca/MedImmune: Consultancy, Research Funding; PerkinElmer: Consultancy, Research Funding; Janssen/Johnson and Johnson: Consultancy, Research Funding; Argos: Consultancy; Bayer: Consultancy; Definiens: Consultancy; OncoSec: Consultancy, Research Funding; PrimeVax: Consultancy, Equity Ownership; Peregrine: Consultancy; UbiVac: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Co-Founder and managing Member of LLC; Ventana/Roche: Consultancy; Viralytics: Consultancy, Research Funding. Bonvini: MacroGenics, Inc.: Employment, Equity Ownership, Research Funding. Wigginton: MacroGenics: Employment, Equity Ownership. Davidson-Moncada: MacroGenics: Employment, Equity Ownership.

Abstract: The COVID-19 pandemic has created a high demand on personal protective equipment, including disposable N95 masks. Given the need for mask reuse, we tested the feasibility of vaporized hydrogen peroxide (VHP), ultraviolet light (UV), and ethanol decontamination strategies on N95 mask integrity and the ability to remove the infectious potential of SARS-CoV-2. Methods: Disposable N95 masks, including medical grade (1860, 1870+) and industrial grade (8511) masks, were treated by VHP, UV, and ethanol decontamination. Mask degradation was tested using a quantitative respirator fit testing. Pooled clinical samples of SARS-CoV-2 were applied to mask samples, treated, and then either sent immediately for real-time reverse transcriptase–polymerase chain reaction (RT-PCR) or incubated with Vero E6 cells to assess for virucidal effect. Results: Both ethanol and UV decontamination showed functional degradation to different degrees while VHP treatment showed no significant change after two treatments. We also report a single SARS-CoV-2 virucidal experiment using Vero E6 cell infection in which only ethanol treatment eliminated detectable SARS-CoV-2 RNA. Conclusions: We hope our data will guide further research for evidenced-based decisions for disposable N95 mask reuse and help protect caregivers from SARS-CoV-2 and other pathogens.