ACAAI 2025 | CS2015 (OX40L/TSLP Bispecific Antibody) Makes International Debut

SUZHOU, China, Nov. 6, 2025 /PRNewswire/ -- CStone Pharmaceuticals ("CStone," HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, autoimmune/inflammation, and other key disease areas, today announced that the Company will present one of its autoimmune and inflammation pipeline assets, CS2015 (OX40L/TSLP bispecific antibody), in the format of an ePoster plus an on-site oral presentation at the 2025 Annual Scientific Meeting of the American College of Allergy, Asthma & Immunology (ACAAI). ACAAI is one of the most influential academic conferences in the fields of allergies, asthma, and immunology, attracting experts and scholars around the world to discuss the latest scientific advancements. This marks the first presentation of CS2015 at an international academic conference. The full content of the abstract and eposter is now officially available on the ACAAI website.

Key highlights of the presentation:

CS2015 features an asymmetric molecular design that simultaneously targets OX40L andTSLP, two clinically validated critical regulators of type 2 inflammation. The molecule incorporates an engineered Fc region with reduced binding affinity for FcγR, which extends its in vivo half-life and optimizes its pharmacokinetic (PK) profile to support long-term dosing intervals. CS2015 also exhibits excellent molecular stability, facilitating the development of high-concentration subcutaneous formulations. Its strong developability profile further supports high-yield and scalable manufacturing.

1.      Dual Blockade:

CS2015 lead molecule demonstrated potent inhibition of OX40L/OX40 and TSLP/TSLPR downstream signaling:

• CS2015 potently interrupted the engagement of hOX40L on hOX40 reporter cells and hTSLP on hTSLPR/IL-7Rα reporter cells, respectively;
• The blocking activities of CS2015 were comparable to those of benchmark (parental) antibodies, with single or sub nanomolar IC50s.

2.      Robust Inhibition of Inflammatory Responses:

CS2015 lead molecule inhibited the release of inflammatory cytokines from primary CD4+ T cells stimulated by TSLP/OX40L and suppressed TSLP-induced release of TARC (CCL17) in human monocytes and peripheral blood mononuclear cells (PBMC).

3.      Early Signs of Efficacy:

CS2015 demonstrated potent disease control activities in Atopic Dermatitis (AD) model with OX40 and TSLP humanized mice. In MC903-induced AD models, CS2015 lead molecule:

• Rapidly reduced skin lesion severity including ear and epidermal thickening;
• Decreased immune cells, especially mast cells infiltration;
• Reduced itch events.

4.      Durability Advantage:

CS2015 demonstrated superb PK profiles in Non-Human Primate (NHP), supporting long-term dosing intervals:

• CS2015 lead molecule K19LS exhibited a mean half-life of 21 days (504.6 hours, Subcutaneous [SC]) and 25.7 days (617.6 hours, Intravenous [IV]);
• K19LS had a clearance rate of 2.4 (SC) and 2.7 (IV) ml/day/kg, and was well-absorbed, with outstanding bioavailability.

5.      Outstanding drug-like properties:

Beyond the data shown in the poster, CS2015 further demonstrated:

• Outstanding accelerated stability under high-temperature stress (40°C);
• Low viscosity (scored at only 3.7 for a 100 mg/ml solution), promising for subcutaneous injection at high-concentration;
• Potent efficacy in the intranasal OVA/TSLP-induced asthma model by decreasing the secretion of IL-4, CCL17, IgE, etc., and alleviating pulmonary pathological changes.

CStone will further advance the development of CS2015 to treat Th2 cell-mediated inflammation diseases, including AD, asthma, hidradenitis suppurativa (HS), chronic obstructive pulmonary disease (COPD), Chronic Rhinosinusitis with Nasal Polyps (CRSwNP), etc.

The presentation schedule is as follows:
Title: CS2015 a TSLP/OX40L Bispecific Antibody as a Potential Novel Therapeutic Agent for Type 2 Inflammation Diseases
Presentation Type: ePoster display & 15-min on-site oral presentation (ePoster ID: R377)
Abstract ID: 8079
Date & Time: Friday, November 7, 3:05 PM ET
Location: ePoster Area of the West Exhibit Hall, Monitor 22
*The abstract and ePoster have been officially available on ACAAI website: https://epostersonline.com/acaai2025/.

About CStone

CStone (HKEX: 2616), established in late 2015, is an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, autoimmune/inflammation, and other key disease areas. Dedicated to addressing patients' unmet medical needs in China and globally, the Company has made significant strides since its inception. To date, the Company has successfully launched 4 innovative drugs and secured approvals for 16 new drug applications covering 9 indications. The company's pipeline is balanced by 16 promising candidates, featuring potentially first-in-class or best-in-class antibody-drug conjugates (ADCs), multispecific antibodies, immunotherapies and precision medicines. CStone also prides itself on a management team with comprehensive experiences and capabilities that span the entire drug development spectrum, from preclinical and translational research to clinical development, drug manufacturing, business development, and commercialization. For more information about CStone, please visit: www.cstonepharma.com. 

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SOURCE CStone Pharmaceuticals