SHANGHAI, China, June 4, 2026 — ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (ImmuneOnco; HKEX Stock Code: 01541.HK) announced today that the latest preliminary results from its Phase Ib/II clinical trial evaluating amourofavfop alfa (IMM0306) in patients with moderate-to-severe active systemic lupus erythematosus (SLE) were presented as a poster at the 2026 European Alliance of Associations for Rheumatology (EULAR) Annual Congress. The data demonstrated that amourofavfop alfa achieved profound B-cell depletion while exhibiting an excellent safety and tolerability profile, alongside robust and durable clinical efficacy.

Poster Presentation
IMC-002 (IMM0306), a First-in-Class CD20/CD47 Bispecific Fusion Protein, Demonstrates Encouraging Efficacy in Patients with Moderate to Severe Active Systemic Lupus Erythematosus (SLE) in the Open-label Phase Ib/2 Study

Drug Background: Dual-Target Mechanism for Synergistic Efficacy
Amourofavfop alfa is a bispecific fusion protein targeting both CD20 and CD47. Its unique molecular design is engineered to function through a dual mechanism: it leverages the CD20 target to mediate antibody-dependent cellular cytotoxicity (ADCC), while simultaneously blocking the CD47 "don't eat me" signal to enhance antibody-dependent cellular phagocytosis (ADCP), thereby achieving more efficient clearance of pathogenic B cells.

Unlike conventional CD47 antibodies, amourofavfop alfa does not bind to human red blood cells. This fundamentally mitigates the risk of hemolytic anemia and prevents antigen sink, allowing greater drug enrichment in target tissues to exert therapeutic effects.

Key Data: Potent, Durable, and Safe
This open-label, multi-center Phase Ib dose-escalation study enrolled 32 patients with moderate-to-severe active SLE who met the 2019 EULAR/ACR classification criteria. The study evaluated the safety, pharmacokinetics, and preliminary efficacy across four dose cohorts ranging from 0.8 mg/kg to 2.0 mg/kg.

As of the data cutoff date of March 5, 2026, key findings include:

● Excellent Safety Profile with Zero CRS as a Highlight
• Favorable Tolerability: No dose-limiting toxicities (DLTs) were observed at any dose level.
• Manageable Adverse Events: Most treatment-emergent adverse events (TEAEs) were mild. The most common Grade 3 adverse event was thrombocytopenia (4/32, 12.5%), which resolved spontaneously without clinical sequelae.
• Key Safety Advantages: No cytokine release syndrome (CRS) of any grade occurred. No clinically significant Grade 3 infections were observed, and no treatment-related serious adverse events (SAEs) were reported. Immunoglobulin levels remained stable, demonstrating an exceptional safety profile.

● Robust Efficacy with Complete B-cell Depletion and Durable Responses
• Profound and Rapid Depletion: Following the first dose, peripheral blood CD19+ B cells in all patients were depleted to undetectable levels (<5 cells/μL).
• B-cell Reconstitution Characteristics: B-cell reconstitution began approximately 8 weeks post-first dose; however, plasmablasts and memory B cells remained persistently suppressed, which may correlate with the durable response to treatment.
• Positive Clinical Responses: SRI-4 response rates at Week 24 were outstanding across all three dose cohorts, with efficacy sustained through Week 52:

• 0.8 mg/kg cohort: 71.4%

• 1.2 mg/kg cohort: 72.7%

• 1.6 mg/kg cohort: 80.0%
  • Significant Improvement in Disease Activity: SLEDAI-2K scores decreased significantly. Clinical manifestations at baseline, including arthritis, rash, alopecia, and vasculitis, largely resolved. Hematuria, proteinuria, and serological markers (dsDNA, C3/C4) showed marked improvement.

Future Outlook: Recommended Phase 2 Doses (RP2Ds) Established
Based on the highly favorable benefit-risk profile, the research team officially announced at the EULAR congress that 1.2 mg/kg and 1.6 mg/kg have been established as the recommended Phase 2 doses (RP2Ds).

Dr. Wenzhi Tian, Chairman, CEO, and CSO of ImmuneOnco, stated:
"The preliminary data presented at EULAR 2026 for amourofavfop alfa are highly encouraging. It successfully breaks the dilemma in autoimmune disease treatment where 'potency' and 'safety' are often mutually exclusive. Notably, amourofavfop alfa did not induce CRS of any grade in clinical trials. This not only validates the elegance of our molecular design but also proves that dual-target synergy can achieve precise 'clearance' of pathogenic B cells while maintaining an excellent safety profile. This marks a solid step forward in our journey to conquer refractory autoimmune diseases such as moderate-to-severe SLE."

Dr. Zhuli Wu, Chief Medical Officer of ImmuneOnco, stated:

"In the Phase Ib study, we were delighted to observe an outstanding benefit-risk profile for amourofavfop alfa. Based on comprehensive data evaluation, the research team has officially established 1.2 mg/kg and 1.6 mg/kg as the recommended Phase 2 doses (RP2Ds). Currently, a larger-scale, randomized, double-blind, placebo-controlled Phase II clinical study was fully initiated in April 2026. We look forward to further validating the clinical value of amourofavfop alfa through subsequent confirmatory studies, aiming to provide a more effective and safer novel therapeutic option for patients with moderate-to-severe SLE worldwide as soon as possible."