Abstract CT213: NEON-1: a first-in-human phase I open-label study of ALPN-202, a conditional CD28 costimulator and dual checkpoint inhibitor, in advanced malignancies

BACKGROUND: Checkpoint inhibitors (CPI) targeting the PD-1 and CTLA-4 pathways have demonstrated significant clinical benefit in multiple tumors, but the majority of patients exhibit or develop resistance, at least in part due to insufficient activation and/or excessive exhaustion of tumor-specific T cells. Strong preclinical rationale exists to combine CPIs with T cell costimulatory agonists, but such approaches have not yet translated into significantly improved clinical benefit. The majority of these approaches, though, have not targeted CD28, a critical T cell costimulator recently recognized as a key target of checkpoint inhibition. ALPN-202 is a variant CD80 vIgD-Fc fusion that mediates PD-L1-dependent CD28 costimulation and inhibits the PD-L1 and CTLA-4 checkpoints. As monotherapy, ALPN-202 has demonstrated superiority to CPI-only therapies in tumor models, while demonstrating a favorable safety profile in preclinical toxicology studies. METHODS: This is a cohort-based, open-label dose escalation and expansion study in adults with advanced solid tumors or lymphoma (NCT04186637). The objectives of this study are to evaluate the safety, efficacy, pharmacokinetics, anti-drug antibodies, and pharmacodynamics of ALPN-202. Subjects who are refractory or resistant to standard therapy (including approved CPIs), or without available standard or curative therapy are eligible. ALPN-202 is administered by IV infusion. After two single-subject cohorts (0.001 mg/kg, 0.01 mg/kg), a standard 3+3 dose escalation (0.1-20 mg/kg) has been implemented with two dose schedules in parallel, Q1W and Q3W. Thereafter, expansion cohorts are planned to enroll subjects at a selected dose regimen(s) in selected indications. Biomarkers include tumor measurements of PD-L1, CD28, CD80 and CD86 to explore the possible relationship between baseline expression and outcomes. Other pharmacodynamic analyses include target saturation, inflammatory cytokines and immunophenotyping of circulating leukocytes. As of January 2021, the trial is continuing as planned; no DLTs have been observed through the 0.3 mg/kg cohorts (dose level 4). Citation Format: Mark Voskoboynik, Justin C. Moser, Nehal Lakhani, Michael Millward, Diwakar Davar, Wael A. Harb, Jing Yang, Gary Means, Kristi Manjarrez, Almudena Tercero, Hany Zayed, Jan Hillson, Christine Dela Cruz, Graciela Perez, Stanford L. Peng. NEON-1: a first-in-human phase I open-label study of ALPN-202, a conditional CD28 costimulator and dual checkpoint inhibitor, in advanced malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT213.