NextPoint Therapeutics has announced the dosing of the first subject with NPX267 in a trial to treat patients with solid tumours.

The Phase Ia/Ib open-label, multi-centre, first-in-human clinical trial will evaluate NPX267 in solid tumours known to express HHLA2, a tumour antigen upregulated in several human tumours independently of PD-L1.

It comprises a dose escalation and an expansion stage for assessing NPX267’s pharmacokinetics, and immunogenicity in patients with metastatic solid tumours, including epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC), as well as other indications.

The trial will also evaluate the tolerability and biomarker strategy of NPX267 in these patients.

NextPoint Therapeutics CEO Detlev Biniszkiewicz said: “Many cancers hijack the HHLA2 pathway to evade the immune system, whose signalling mechanisms were independently co-discovered by NextPoint’s scientific co-founders, Dr XingXing Zang and Dr Gordon Freeman.

“Because HHLA2 is expressed independently of PD-L1 and is often highly expressed in PD-L1-negative cancers, targeting the HHLA2-KIR3DL3 interaction is a promising new approach for patients with cancer.”

The first-in-class monoclonal antibody NPX267 acts on killer cell immunoglobulin-like receptor 3DL3 (KIR3DL3) and helps prevent immune escape in solid tumours.

It blocks the KIR3DL3 binding on exhausted T and NK cells to HHLA2 expressed on tumour cells and can reactivate tumour antigen-primed immune cells in tumours.

NextPoint Therapeutics chief medical officer Leena Gandhi said: “This study will provide important data on the therapeutic activity of NPX267, as well as the mechanism of HHLA2-mediated immunosuppression via KIR3DL3 and inform our clinical strategy for developing precision immunotherapeutic treatments for patients.”