On October 30, 2025 REGiMMUNE Limited ("REGiMMUNE" or "the Company"), a clinical stage biopharma company developing novel immune therapeutics targeting regulatory T cells (Treg), reported preclinical data of its antibody program at the meeting of Antibody Engineering & Therapeutics Asia 2025 in Kyoto, Japan from Oct. 20 – 22.

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REGiMMUNE, while pursuing RGI-2001 in advanced clinical development for (Graft vs Host Disease (GvHD), armed with our long-time expertise in human immunology and Treg cells, has been actively developing its therapeutic antibody program. This pipeline currently includes RGI-6004 and AB01, both targeting tumor infiltrating Treg cells, reflecting the two strategies of therapeutic modulation of Treg cells, namely, depleting vs silencing, and AB08-H1 targeting a surface marker shared by blood-borne and solid malignancies.

The presentation in Kyoto included RGI-6004 and AB08-H1. RGI-6004 was developed to highly selectively target tumor infiltrating Treg cells while maintaining all other immune effector cells intact to alleviate the immune suppression in the tumor microenvironment, and consequently enhance anti-cancer immunity. AB08-H1 is an antibody developed to kill malignant cells of Hodgkin & Non-Hodgkin diseases and solid cancer cells via a unique target.

RGI-6004, an Afucosylated Antibody to Target GARP/LAP-TGFβ1 for Selective Depletion of Activated Tregs. RGI-6004, a fully human IgG1 against GARP/Latent-TGFb1 complex, designed to deplete tumor infiltrating activated Treg cells. The antibody specifically binds to activated human Treg cells with high affinity, but none to non-activated Treg cells, and CD4+ and CD8+ T effector cells. The antibody recognizes tumor infiltrating Treg cells in clinical solid tumor tissues. Its afucosylated version highly selectively depletes activated Treg cells with a significantly enhanced efficacy of ~10 pM, but none of CD4+ and CD8+ effector T cells, while granzyme B induction & proliferation of CD4+ and CD8+ effector T cells are not affected. RGI-6004 has minimal impact on platelets (counts and degranulation), minimal binding to major immune cells, nor observable impact on hematological profile of normal human blood. In cynomolgus monkey, its t1/2 is shown to be ~10 days, while its clinical hematology, coagulation, blood chemistry, immunophenotyping in peripheral blood, serum cytokine analysis, and pathology, does not demonstrate safety alarms. In sum, the behavior of RGI-6004 highlights the potential as a next-generation Treg-depleting agent in cancer immunotherapy.

AB08-H1, A humanized antibody that directly kills cancer target cells without ADCC and CDC. AB08-H1 is a humanized IgG that specifically targets pan MHC II (synonym for HLA II, human leukocyte antigen). Upon binding to the cell surface MHC class II molecule, the antibody induces homotypic aggregation, lysosomal membrane permeabilization, and ultimately cell lysis of the target malignant cells directly without the involvement of ADCC and CDC. REGiMMUNE overcame the original bottleneck of protein production of the humanized IgG, developed a high yield method to manufacture it in mammalian cells. As MHC Class II molecules are found highly expressed on lymphoid malignant cells, and have been increasingly recognized to express highly in major solid cancer cells, AB08-H1 is expected to treat various types of lymphoid malignancies (Hodgkin and Non-Hodgkin lymphomas), and solid cancers.

REGiMMUNE is encouraged by the recent news of Nobel Prize in Physiology granted to Dr. Shimon Sakaguchi and others, for their works on Treg cells. We are pleased to see that the fundamental roles of Treg cells in autoimmune disease, GvHD, cancer, and infectious disease are recognized in highest profile. REGiMMUNE is committed to developing therapeutics with, as Dr. Shimon Sakaguchi well put it, Treg-up strategies vs Treg-down strategies.

(Press release, REGimmune, OCT 30, 2025, View Source [SID1234657165])