Canada-based clinical-stage biotechnology company Zymeworks Inc. (NASDAQ:ZYME) announced on Monday that the US Food and Drug Administration has cleared its investigational new drug application for ZW251, a novel antibody-drug conjugate targeting glypican-3 for the treatment of hepatocellular carcinoma.

ZW251 is the second antibody-drug conjugate from Zymeworks' pipeline to enter clinical development using its proprietary topoisomerase 1 inhibitor payload, ZD06519. The molecule consists of a humanised IgG1 antibody conjugated via a peptide cleavable linker to a camptothecin-based payload, with a drug-antibody ratio of four.

The design of ZW251 aims to optimise dosing flexibility, which may benefit patients with hepatocellular carcinoma who often have impaired liver function.

Preclinical data showed that ZW251 demonstrated strong anti-tumour activity across multiple patient-derived xenograft models with varied glypican-3 expression. The compound also exhibited favourable tolerability in non-human primate studies at doses up to 120 mg/kg.

A Phase 1 clinical trial for ZW251 is expected to begin later this year.