On October 28, 2025, ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (referred to as "ImmuneOnco," with the stock code 01541.HK on the Hong Kong Stock Exchange) presented the latest results of the Phase Ib/II clinical study of Amulirafusp Alfa (IMM0306) for the treatment of Systemic Lupus Erythematosus (SLE) in the form of a poster at the 2025 Annual Meeting of the American College of Rheumatology (ACR) held in Chicago, Illinois, USA, offering new hope for the treatment of SLE patients.

Highlights of the Poster Abstract of Amulirafusp Alfa (IMM0306) at ACR Convergence 2025:

IMC-002 (Amulirafusp Alfa), a first-in-class bispecific fusion protein, demonstrated significant improvements in disease activity measures and biomarkers in an open-label Phase Ib/II study targeting patients with moderate to severe active SLE.

• Presentation Format: Poster Presentation

• Session: Systemic Lupus Erythematosus --- Treatment Poster III Session

Key Points:

Efficacy Results:

• Significant Increase in SRI-4 Response Rate: At week 24, 71.4% (5/7) of patients receiving the      0.8mg/kg dose and 80.0% (4/5) of patients receiving the 1.2mg/kg dose achieved an SRI-4 response, indicating good therapeutic effects.

• Significant Improvement in Clinical Symptoms: Arthritis, vasculitis, and alopecia all resolved.

• Significant Improvement in Biomarkers: Key biomarkers, including anti-dsDNA antibodies, 24-hour urine protein, and complement C3/C4, all showed significant improvement trends. This suggests      that Amulirafusp Alfa can effectively modulate the immune system of patients and reduce disease activity.

• Deep  B Cell Depletion and Reconstitution: Both groups of patients achieved deep B cell depletion, demonstrating the potential for treating B cell-driven autoimmune diseases. Additionally, B cell immune reconstitution was observed in five patients between weeks 12 and 24, which may contribute to long-term immune balance in patients.

Safety Summary:

• Overall TRAEs:  Among the 19 subjects, 14 (73.7%) reported at least one treatment-related adverse      event (TRAE), most of which were mild to moderate.

• Grade 3 or Higher TRAEs:  Only 2 (10.5%) of the 19 subjects reported Grade 3 or higher TRAEs, both      of which were transient thrombocytopenia that resolved spontaneously within 4-5 days without intervention, indicating good safety of the drug at higher doses.

• No Serious TRAEs: No dose-limiting toxicity (DLT) events, cytokine release syndrome (CRS), or      significant infectious events occurred. Immunoglobulin levels remained within the normal range. No subjects experienced dose adjustment or death due to TRAEs, indicating that the drug did not cause significant safety issues during the treatment process.

• These results indicate that Amulirafusp Alfa has good safety and tolerability in patients with moderate to severe active SLE and no serious treatment-related adverse events occurred.

Study Summary:

In this study, Amulirafusp Alfa demonstrated good safety and tolerability at both the 0.8 mg/kg and 1.2 mg/kg dose levels and achieved positive results in reducing disease activity measures and improving biomarkers. The trial for the 1.6 mg/kg dose group is also being actively promoted, with the expectation of achieving better efficacy. As a potential new therapeutic option, Amulirafusp Alfa has the potential to provide a new treatment regimen for B cell-mediated autoimmune diseases.

Data Cut-off Date: September 10, 2025

About Systemic Lupus Erythematosus (SLE):

SLE is a complex autoimmune disease characterized by recurrent flare-ups, causing long-term suffering and a decline in quality of life for patients. Current treatments, while providing some symptom relief, still leave many patients facing issues such as poor treatment response, disease relapse, and severe side effects from corticosteroid therapy.

About Amulirafusp Alfa (IMM0306):

Amulirafusp Alfa is a fusion protein composed of a CD20 monoclonal antibody and an engineered SIRPα domain on both heavy chains. It has a unique mechanism: compared to rituximab, it has stronger antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) activities; it does not bind to human red blood cells in vitro; CD47 is highly expressed in all B cell subsets, while CD20 is barely expressed in plasmablasts. These characteristics give it a potential advantage in treating B cell-mediated autoimmune diseases.

Statement from Dr. Wen Zhi Tian, Founder, Chairman, CEO, and CSO of ImmuneOnco:

"We are honored to share the latest progress of our research in the treatment of moderate to severe SLE at the 2025 ACR Annual Meeting. We are well aware of the pain suffered by SLE patients and the limitations of existing treatments. As a first-in-class bispecific fusion protein, Amulirafusp Alfa has shown promising results in the Phase Ib/II clinical study, with rapid and sustained B cell depletion without affecting immune reconstitution and ensuring no secondary infectious events, and overall good safety. These achievements have encouraged us and filled us with confidence for the future of Amulirafusp Alfa. We will continue to accelerate the development and strive to bring new treatment options to SLE patients as soon as possible to improve their quality of life."