Abstract CT253: Phase 1/2 study of the safety, pharmacokinetics, and preliminary clinical activity of BT7480 in patients with nectin-4 associated advanced malignancies

Abstract

Abstract Background: Bicycles are a novel class of synthetic molecules formed by using a central scaffold to constrain short linear peptides into a stabilized bi-cyclic structure, which can then be readily conjugated to other molecules. BT7480 is a trimeric first-in-class Bicycle tumor-targeted immune cell agonist (Bicycle TICA) comprised of two unique bicyclic peptides: one that binds to Nectin-4 and two identical Bicycles that bind and agonize CD137. The resulting multi-specific molecule stimulates an immune response in the presence of both Nectin-4-expressing tumor cells as well as CD137-expressing immune cells. Nectin-4, a cell adhesion molecule overexpressed on the surface of tumor cells and CD137, a costimulatory receptor expressed on immune cells, are co-expressed in a variety of solid tumors including lung, head and neck, breast, ovarian, and bladder. Co-ligation of Nectin-4 and CD137 by BT7480 is hypothesized to induce oligomerization and activation of CD137, resulting in a tumor-localized costimulatory signal. A favorable preclinical profile supported the initiation of this first-in-human study to investigate the safety and efficacy of BT7480 in patients with solid tumors associated with Nectin-4 expression (NCT05163041). Methods: This is a phase 1/2, open-label, multicenter study to assess safety, clinical activity, and pharmacokinetics (PK) and pharmacodynamics (PD) of BT7480. Patients must have an advanced malignancy associated with Nectin-4 expression that is not eligible for standard therapy. Additional key criteria include ≥18 years of age, ECOG of 0 or 1, adequate organ function, and no prior therapy with a CD137-targeted agent. Patients are treated at one of the escalating doses (3+3 design) by weekly IV infusion in a 4-week cycle. Primary objectives are to assess safety (phase 1) and clinical activity per RECIST v1.1 (phase 2). Secondary objectives include assessment of PK parameters, measurement of anti-drug antibodies, and evaluation of CD137 target engagement in blood. Key exploratory objectives include evaluating pharmacogenomics, ctDNA, and biomarkers in blood and tumors associated with pharmacological activity, including signals of immune activations and target expression. PK and PD analyses will be performed to support dose escalation decisions and to further the understanding of safety and clinical activity signals as a result of treatment with BT7480. This study is actively recruiting. Citation Format: Thomas R. Evans, Afshin Dowlati, Juanita S. Lopez, Mohammed M. Milhem, Jordi Rodón Ahnert, Alexander Spira, Richard D. Carvajal, Matthew Zibelman, Sebastien J. Hazard, Amy Dickson, Lei Xu, Heather Cohen, Justin Bader, Kristen Hurov, Rajiv Sharma, Dominic Smethurst, Kyriakos P. Papadopoulos. Phase 1/2 study of the safety, pharmacokinetics, and preliminary clinical activity of BT7480 in patients with nectin-4 associated advanced malignancies [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 CT253.