BETA PRIME: Phase I study of AdAPT-001 as monotherapy and combined with a checkpoint inhibitor in superficially accessible, treatment-refractory solid tumors

AdAPT-001 is an investigational therapy consisting of a replicative type 5 adenovirus armed with a TGF-β receptor-immunoglobulin Fc fusion trap, designed to neutralize isoforms 1 and 3 of the profibrotic and immunosuppressive cytokine, TGF-β. In preclinical studies with an immunocompetent mouse model, AdAPT-001 eradicated directly treated 'cold' tumors as well as distant untreated tumors, and, from its induction of systemic CD8+ T cell-mediated antitumor immunity, protected the mice from rechallenge with tumor cells. AdAPT-001 also sensitized resistant tumors to checkpoint blockade. This manuscript describes the rationale and design of the first-in-human phase I, dose-escalation and dose-expansion study of AdAPT-001 alone and in combination with a checkpoint inhibitor in adults with treatment-refractory superficially accessible solid tumors. Plain language summary The purpose of this study is to find out more about the experimental oncolytic virus called AdAPT-001 that has been designed to selectively eliminate cancer cells. The virus is also designed to make a particular protein called a TGF-β trap, which neutralizes TGF-β, an overproduced chemical in cancer cells that puts the immune system into a comatose state. This article discusses a clinical trial called BETA PRIME for patients with no other standard treatment options. The trial will explore different doses of AdAPT-001 both alone and in combination with an approved checkpoint inhibitor or another immunotherapy, which blocks the 'off' signal on immune cells, to determine the safest and best dose. Clinical Trial Registration: NCT04673942 (ClinicalTrials.gov. Twitter abstract BETA PRIME, a phase I clinical trial, will study AdAPT-001, an oncolytic adenovirus that carries a TGF-β 'trap' +/- a checkpoint inhibitor with the ultimate objective to turn 'cold' tumors 'hot' and increase response rates.