ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (IMMUNEONCO-B, 01541) has reported two key advances for its independently developed activin receptor type IIA-Fc fusion protein, IMC-003/IMM72.

The company has dosed the first patient in a Phase Ib/IIa study evaluating IMC-003 in pulmonary arterial hypertension (PAH), officially moving the asset into the patient-validation stage.

Concurrently, ImmuneOnco has finalised enrolment for all cohorts in its Phase I single-ascending-dose (SAD) and multiple-ascending-dose (MAD) trials in postmenopausal healthy women: • SAD study: Seven dose cohorts, with IMC-003 tolerated up to 8 mg/kg. No dose-limiting toxicities (DLTs) observed; most treatment-related adverse events (AEs) were Grade 1 and no Grade 3 or higher AEs were reported. • MAD study: Four dose cohorts fully enrolled; the fourth cohort (2 mg/kg) completed enrolment on 17 August 2026. Early safety read-outs showed only Grade 1–2 AEs, no Grade 2 or higher haemoglobin-increase events, and no DLTs in the first three cohorts.

IMC-003 targets PAH via an ActRIIA-Fc mechanism similar to the approved drug sotatercept (Winrevair™). Preclinical studies demonstrated IMC-003’s binding and signalling-blockade activities at five times those of sotatercept and superior efficacy in established animal PAH models, including improvements in right ventricular systolic pressure and pulmonary arteriole wall area. Enhanced selectivity for Activin A may allow therapeutic benefit at lower exposure and potentially reduce bleeding risk.

The company reiterates that there is no assurance IMC-003 will ultimately achieve regulatory approval or commercial success.