Shanghai, China, April 22, 2026 — ImmuneOnco Biopharmaceuticals (Shanghai) Inc. ("ImmuneOnco", HKEX Stock Code: 01541.HK) announced today that its subsidiary, ImmuneCare Biopharmaceuticals (Shanghai) Co., Ltd. ("ImmuneCare"), has successfully completed the enrollment of all subjects in the Multiple Ascending Dose (MAD) study of its self-developed IMC-003/IMM72 (ActRIIA-Fc fusion protein) for Pulmonary Arterial Hypertension (PAH) in healthy volunteers. This milestone represents a solid step forward in the clinical development of IMC-003, laying a crucial foundation for evaluating its safety, tolerability, pharmacokinetics, and pharmacodynamics under multiple dosing regimens, and holding promise to bring new hope to patients suffering from PAH.

Pulmonary Arterial Hypertension (PAH) is a progressive and life-threatening pulmonary vascular disease characterized by persistently elevated pulmonary artery pressure and pulmonary vascular resistance (PVR). Patients initially experience symptoms such as dyspnea, decreased exercise tolerance, chest tightness, and fatigue, which ultimately progress to right heart failure and death. With a historically low 5-year survival rate for untreated patients, PAH is often referred to as the "cancer of cardiovascular diseases." The approval of Merck's new drug, Winrevair™, in the U.S. in March 2024 has propelled PAH treatment from an era of "symptomatic relief" into a new era of etiological therapy aimed at "reversing pulmonary vascular remodeling." The drug quickly grew into a blockbuster, achieving sales of $1.443 billion in 2025 following its launch (based on Merck's 2025 financial report).

IMC-003 is an Activin Receptor Type IIA (ActRIIA)-Fc fusion protein independently developed by ImmuneCare. It shares a similar mechanism of action with Winrevair™, fundamentally improving the homeostasis of vascular smooth muscle cells and pulmonary vascular remodeling by targeting the underlying disease mechanism. Compared to existing comparable drugs, IMC-003 possesses unique, differentiated characteristics. Its ActRIIA extracellular functional domain has been genetically engineered to enhance binding and blocking activity against the ligand Activin A, while also improving the homogeneity of the drug product. In Sugen5416-hypoxia and MCT-induced PAH animal models, IMC-003 demonstrated superior efficacy compared to existing drugs in the same class. Its high selectivity for Activin A suggests that IMC-003 may achieve robust efficacy at lower exposure levels in clinical applications, potentially reducing the risk of bleeding and demonstrating a better safety profile.

Executive Commentary

Dr. Tian Wenzhi

Founder, Chairman, CEO, and CSO of ImmuneOnco; Founder of ImmuneCare

"The completion of subject enrollment for the IMC-003 MAD study is a significant achievement resulting from our team's collective efforts and confirms the positive momentum of the drug's clinical development. Patients with pulmonary arterial hypertension have long faced a dilemma of limited treatment options. Through the development of IMC-003, we aim to provide an innovative treatment regimen with superior efficacy and safety. Moving forward, we will continue to accelerate the clinical development process, looking forward to advancing this differentiated innovative therapy to Phase II clinical trials and commercialization as soon as possible to bring benefits to more patients."