공시 • Jun 12
Cstone Presents Clinical Data for Cs2009 Trispecific Antibody At Asco 2026
CStone presented clinical datasets at ASCO 2026 that further validate the trispecific synergistic mechanism of CS2009 and support its potential to become a next-generation immuno-oncology (I/O) backbone therapy. CS2009 was designed to restore T-cell effector function, remodel the tumor microenvironment (TME), and enhance T-cell priming via simultaneous targeting of PD-1, VEGF, and CTLA-4, aiming to generate deeper and more durable anti-tumor immune responses. The CTLA-4 component is engineered to avoid excessive activation of peripheral CTLA-4 single-positive T cells, thereby reducing systemic immune toxicity. Combined with VEGF-mediated tumor enrichment, this design preserves the immune-stimulatory benefit of CTLA-4 blockade while substantially improving tolerability. Clinical data has demonstrated that CTLA-4-related toxicities with CS2009 are notably lower than that of conventional CTLA-4 antibody regimens, with immune-related adverse events (irAEs) approaching incidence typically seen with PD-1 monotherapy or PD-1-based bispecific antibodies. Unlike conventional CTLA-4 antibodies, which are often limited to two or three doses due to tolerability concerns, CS2009 can be administered continuously, therefore fully leveraging the CTLA-4 mechanism—not only initiating and enhancing existing anti-tumor T-cell responses but also continuously priming new T-cell clones against newly released tumor antigens throughout treatment. Dose-dependent upregulation in ICOS, a recognized pharmacodynamic marker of CTLA-4 pathway activation and T-cell activation, were observed. The ICOS elevation suggests that CS2009 continuously promotes T-cell priming and clonal expansion, validating the biological activity of its CTLA-4 module and providing biological basis for long-term anti-tumor activity. Pharmacodynamic data demonstrated that circulating VEGF levels have declined continuously following dosing, and no clear rebound has been observed after up to 147 days of follow-up. This pattern differs from results reported with traditional anti-VEGF antibodies or PD-1/VEGF bispecifics, potentially due to CS2009's enrichment in the tumor microenvironment and CTLA-4-mediated internalization and clearance of VEGF-antibody complexes. This may reduce reflux of VEGF and its antibody-bound complexes into the peripheral circulation, thereby lowering VEGF-related systemic toxicities such as hypertension and proteinuria. Clinical data demonstrated that the incidence of Grade =3 VEGF-related treatment-related adverse events (TRAEs) is only 5.1%, notably lower than reported rates for certain VEGF-based bispecifics. Promising anti-tumor activity has been observed in several traditionally immunotherapy-insensitive tumor types, including: Immunotherapy-resistant non-small cell lung cancer (NSCLC), pMMR/MSS metastatic colorectal cancer (mCRC), Soft tissue sarcoma (STS), Non-clear cell renal cell carcinoma (nccRCC). The consistent efficacy signals across multiple cold tumors support the ability of CS2009's PD-1, CTLA-4 and VEGF synergism to reshape the immunosuppressive TME, expand the I/O-benefiting population, and demonstrate the potential to transcend the efficacy boundaries of traditional PD-1 inhibitors and PD-1/VEGF bispecifics. Across multiple NSCLC treatment settings, comparable response rates were observed in both squamous and non-squamous patients. CS2009 is showing a trend of consistent benefit across histological subtypes, indicating that its mechanism may not depend on a particular pathologic type and may cover a broader population of NSCLC patients. Safety data from the ongoing Phase I study in a mixed tumor population (N=118): Grade =3 TRAE incidence: 24.6%; Grade =3 irAE incidence: 12.7%; Grade =3 VEGF-related TRAE incidence: 5.1%. Focusing on the later-line NSCLC cohort (n=57): Grade =3 TRAE rate: 19.3%; Grade =3 irAE rate: 12.3%; VEGF-related Grade =3 TRAE rate: 5.3%; Consistent with the safety profile of the overall heavily pretreated mixed-tumor population. CTLA-4-related toxicity appears very well controlled. No new or unexpected safety signals have been identified. The overall safety profile is comparable to that of PD-1/VEGF bispecific antibodies, while VEGF-related toxicity appears substantially lower. CS2009 has demonstrated meaningful clinical activity across multiple "cold" tumors. Monotherapy in Later-Line pMMR/MSS mCRC: All enrolled patients had heavily pretreated, refractory CRC, including cases with BRAF mutations and right-sided tumors. CS2009 monotherapy achieved an ORR of 25% and a DCR of 87.5%. Combination with XELOX in First-Line pMMR/MSS mCRC: The study did not select patients by tumor sidedness, molecular subtype, or liver metastasis; the enrolled population better reflects real-world clinical practice. To date, all six patients have experienced tumor shrinkage, and three patients achieved a partial response (PR) at their first efficacy assessment. ORR was 66.7%, and DCR was 100%. The Company plans to expand the cohort to approximately 40 patients to generate a more comprehensive proof-of-concept (POC) dataset for upcoming discussions with the global regulatory authorities including the U.S. Food and Drug Administration (FDA) and China's National Medical Products Administration (NMPA) on a Phase III global registrational clinical trial. Monotherapy in Later-line Soft Tissue Sarcoma (STS): ORR 33.3%, DCR 66.7%; Monotherapy in Later-line non-clear cell renal cell carcinoma (nccRCC): ORR 33.3%, DCR 100%; Durable responses have also been observed. Notably, the first patient enrolled in Phase I (an Australian female) has experienced sustained tumor shrinkage of more than 40% over 12 months. Later-Line NSCLC Monotherapy (Pretreated with IO, Chemotherapy, ADCs, or Bispecifics): Overall ORR in the 30 mg/kg cohort: 24% (squamous 25%, non-squamous 23.1%, consistent benefit); DCR 60%; In second-line NSCLC (30 mg/kg, post IO + chemotherapy): ORR improved to 30.8%, DCR 84.6%. 6-month duration-of-response (DOR) rate exceeded 80% (i.e., more than 80% of responders remained in response at 6 months); Depth of response has continued to deepen over time; DOR data are still maturing. Later-Line NSCLC in Combination with Docetaxel: All six evaluable patients experienced tumor shrinkage, resulting in an ORR of 66.7% and a DCR of 100%.