Bolt Biotherapeutics, Inc. announced that the first patient has been dosed in a new combination arm of the ongoing multi-center, multi-dose Phase 1/2 clinical trial of BDC-1001. This arm is evaluating BDC-1001 in combination with Bristol Myers Squibb's PD-1 checkpoint inhibitor OPDIVO® (nivolumab). In parallel, Bolt continues to advance the single-agent portion of the study, following the presentation of interim dose-escalation data at the European Society of Medical Oncology Immuno-Oncology (ESMO I-O) Congress 2021.

BDC-1001 is a HER2-targeting Boltbody™ immune-stimulating antibody conjugate (ISAC) (trastuzumab biosimilar conjugated to a toll-like receptor 7 and 8 agonist) in development for the treatment of patients with HER2-expressing solid tumors. Bristol Myers Squibb will provide Opdivo for the combination dose escalation and combination dose expansion portions of the trial. Bolt Biotherapeutics is the study sponsor and will be responsible for costs associated with the trial execution.

BDC-1001 is a human epidermal growth factor receptor 2 (HER2) ISAC comprising a HER2-targeting biosimilar of trastuzumab conjugated with a non-cleavable linker to an innovative TLR7/8 agonist. It is currently being investigated in a Phase 1/2 clinical trial (NCT04278144) in patients with HER2-expressing solid tumors, including breast, gastroesophageal and colorectal. The trial is being conducted in four parts, and the dose-escalation monotherapy part will continue in parallel with the combination therapy study.

Interim monotherapy data presented by Bolt at the European Society of Medical Oncology Immuno-Oncology (ESMO I-O) Congress 2021 demonstrated a safe and well-tolerated profile with early clinical activity, supporting continued dose escalation and evaluation of a weekly dosing regimen.