Henlius Advances First-in-Class B7-H3 Sialidase Fusion Protein HLX316/E-688 into First-in-Human Phase 1 Trial in China

Henlius announces that its first‑in‑class B7‑H3–targeted sialidase fusion protein HLX316 (also known as E‑688) has been administered to the first patient in a Phase 1 clinical trial in China.

The study (HLX316‑FIH101, NCT07541534) is an open‑label, first‑in‑human Phase 1 trial in patients with advanced or metastatic solid tumors, designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti‑tumor activity of HLX316.

HLX316 is an engineered human sialidase Fc fusion protein that targets B7‑H3 (CD276) and is designed to desialylate tumor‑associated glycans, thereby modulating glyco‑immune checkpoints and enhancing both innate and adaptive anti‑tumor immunity.

Development of HLX316 is based on Henlius’s proprietary VHH‑targeting platform and Palleon Pharmaceuticals’ EAGLE (Enzyme‑Antibody Glycan‑Editing) platform, under a collaboration agreement between Henlius and Palleon.

Preclinical data show that HLX316 selectively accumulates in tumor tissue, improves tumor desialylation and durability, and demonstrates stronger efficacy than non‑targeted sialidase, B7‑H3 antibodies, and anti‑PD‑1 antibodies in relevant models, with a favorable tolerability profile in non‑human primate toxicology studies.

The Phase 1 trial consists of two parts:
dose escalation (Phase 1a) with five dose levels (1–30 mg/kg administered once weekly) and dose expansion (Phase 1b); the primary endpoints include incidence of dose‑limiting toxicities, determination of maximum tolerated dose and recommended Phase 2 dose, and objective response rate (ORR).

The IND for this Phase 1 study was approved by China’s National Medical Products Administration (NMPA) in March 2026, enabling the initiation of first‑in‑human evaluation of this novel glyco‑immune checkpoint modulator in China.