Shanghai, China – August 27, 2026 – ImmuneOnco Biopharmaceuticals (Shanghai) Inc. ("ImmuneOnco" or the "Company"; HKEX Stock Code: 01541.HK) today announced that the first patient has been enrolled and dosed in the IMM2510-HCC-201 study, a Phase II clinical trial evaluating palverafusp alfa (IMM2510) in combination with tazlestobart (IMM27M) for the treatment of first-line advanced hepatocellular carcinoma (HCC). The study is designed to assess the preliminary anti-tumor efficacy and safety of the combination in this patient population.

Differentiated yet Complementary Mechanisms of Action

Palverafusp alfa (IMM2510) is a VEGF×PD-L1 dual-targeting bispecific molecule built on ImmuneOnco's proprietary mAb-Trap technology platform. By simultaneously blocking the PD-L1 immunosuppressive pathway and the VEGF angiogenesis pathway, IMM2510 activates T-cell tumor-killing activity while inhibiting tumor angiogenesis and tumor growth. Its Fc region further mediates antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) effects, activating natural killer (NK) cells and macrophages to engage the body's innate immunity.

Tazlestobart (IMM27M) is a next-generation CTLA-4 antibody with ADCC activity enhanced through genetic engineering. CTLA-4 is a protein receptor expressed on activated T cells that downregulates immune responses by binding to its natural ligands CD80 and CD86 on antigen-presenting cells, delivering inhibitory signals that suppress T-cell function. By blocking the interaction between CTLA-4 and CD80/CD86, IMM27M enhances T cell-mediated anti-tumor immune responses.

Since the initial IND submission for the combination in 2023, clinical development has progressed steadily. The Phase Ib trial in advanced solid tumors has established a recommended Phase II dose (RP2D), with dose-expansion cohorts currently underway in esophageal squamous cell carcinoma (ESCC) and squamous non-small cell lung cancer (sq-NSCLC) following progression on prior immunotherapy. Preliminary data from the dose-escalation phase showed that among six efficacy-evaluable patients with ESCC, three achieved partial response (PR), two had stable disease (SD), and one had immune unconfirmed progressive disease (iUPD), yielding an overall response rate (ORR) of 50% and a disease control rate (DCR) of 83%. These early results demonstrate that the combination is well tolerated and possesses promising anti-tumor activity.

Addressing Unmet Needs in First-Line HCC

Hepatocellular carcinoma is one of the most prevalent malignancies worldwide. The disease is often asymptomatic in early stages, leaving most patients diagnosed at intermediate or advanced stages with limited therapeutic options. The liver's unique immune-tolerant environment creates a tumor microenvironment characterized by profound immunosuppression and active angiogenesis, posing substantial challenges to treatment.

Currently, PD-(L)1 inhibitor plus anti-angiogenic agent combinations represent the global first-line standard of care for advanced HCC, while PD-L1 inhibitor plus CTLA-4 inhibitor regimens such as the STRIDE regimen have also emerged as first-line options. However, existing dual-drug combinations still leave unmet needs in depth of response and resistance.

The IMM2510-HCC-201 study was initiated to address these gaps. This Phase II trial evaluates the safety, tolerability, and anti-tumor activity of the combination in patients with HCC.

Leveraging its unique dual-targeting mechanism against PD-L1 and VEGF, IMM2510 directly addresses the two core drivers of HCC: immunosuppression and aberrant vascular proliferation. Combined with the next-generation CTLA-4 inhibitor IMM27M, the regimen achieves synergistic coverage of three targets—PD-L1, VEGF, and CTLA-4. This strategy aims to achieve more comprehensive immune reactivation and microenvironment modulation, potentially enhancing anti-tumor efficacy beyond current first-line standards and extending patient survival.

Dr. Wenzhi Tian, Founder, Chairman, CEO and Chief Scientific Officer of ImmuneOnco, commented:

"The dosing of the first patient in the IMM2510-HCC study marks an important step in ImmuneOnco's strategic expansion in solid tumors. This milestone validates our efficient clinical execution and underscores our commitment to improving outcomes for patients with liver cancer. We will continue to advance this program with urgency, working to bring meaningful clinical benefits to patients as early as possible."

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

"From early dose exploration to the initiation of this Phase II study, the IMM2510 data have been consistently encouraging. The first patient dosed represents a promising start. Going forward, we will closely monitor safety signals and early efficacy responses, advancing development with scientific rigor. We look forward to the IMM2510 plus IMM27M combination becoming a valuable addition to the treatment landscape for liver cancer."