ASCO 2026 | CStone Presents Updated Clinical Data for CS2009 (PD-1/VEGF/CTLA-4 Trispecific Antibody), Reinforcing Triple-Target Synergy and Delivering Strong Proof-of-Concept
PR Newswire
SUZHOU, China, May 31, 2026
First-line NSCLC – Compelling Activity Across All PD-L1 SubgroupsIn first-line non-small cell lung cancer (NSCLC) patients with high PD-L1 expression (TPS ≥50%), CS2009 monotherapy achieved an objective response rate (ORR) of 81.3% and a disease control rate (DCR) of 100.0%, with consistent benefit across squamous (ORR: 87.5%) and non‑squamous (ORR: 75.0%) histologies. In the PD-L1-negative/low population (TPS ≤5%) squamous NSCLC cohort, CS2009 in combination with chemotherapy achieved an ORR of 75.0% and a DCR of 100.0%; notably, PD-L1-negative patients within this cohort achieved an ORR of 100.0%; the current efficacy readout remains immature due to the short follow‑up for most patients in this cohort.Later-line NSCLC – Potential to Overcome Immunotherapy ResistanceIn heavily pretreated later-line NSCLC, CS2009 demonstrated encouraging antitumor activity, with most patients experiencing sustained tumor shrinkage. Across all dose levels, the 6-month duration of response (DOR) rate reached 85.7%. In the second-/third-line combination cohort, CS2009 achieved an ORR of 66.7% and a DCR of 100.0%. In the 30 mg/kg monotherapy cohort, patients whose disease had progressed following prior immunotherapy (IO) plus platinum-based chemotherapy —— a setting with significant unmet medical need—achieved an ORR of 30.8% and a DCR of 84.6%."Cold Tumors" – Meaningful Activity in Immunotherapy-Refractory Settings In "cold tumors" with limited immunotherapy responsiveness, CS2009 monotherapy produced a 25.0% ORR and 87.5% DCR in heavily pretreated proficient mismatch repair/microsatellite stable metastatic colorectal cancer (pMMR/MSS mCRC). A 66.7% ORR and 100.0% DCR were observed when CS2009 was combined with XELOX in first-line mCRC. The current efficacy readout remains immature due to the short follow‑up for most patients in these two CRC cohorts. Additional monotherapy activity was seen in soft tissue sarcoma (STS) and non‑clear cell renal cell carcinoma (nccRCC) (ORR 33.3% each), reinforcing CS2009's potential to remodel the tumor microenvironment.Updated Safety Data – Favorable Profile Confirmed with Longer Follow-upWith extended follow-up since initial presentation at European Society for Medical Oncology (ESMO) Congress 2025, updated Phase I safety data further confirmed the well-tolerated profile of CS2009. Importantly, no excessive toxicities typically associated with CTLA-4/PD‑(L)1 combinations observed. Among heavily pretreated patients with advanced solid tumors, Grade ≥3 treatment‑related adverse events (TRAE) occurred in 24.6% of patients, immune‑related adverse events (irAE) in 12.7% , and TRAE possibly related to anti-VEGF in 5.1%. This favorable safety profile was consistently maintained across both monotherapy and chemotherapy combination cohorts in first-line NSCLC.Next Step – Phase III Registrational MRCT Planned by Year-EndThe ongoing global Phase I/II trial has enrolled nearly 300 patients across China and Australia, with U.S. Investigational New Drug (IND) clearance now obtained. CStone plans to initiate the first Phase III global multi‑regional registrational trial (MRCT) for CS2009 by the end of 2026.SUZHOU, China, May 31, 2026 /PRNewswire/ -- CStone Pharmaceuticals ("CStone," HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, immunology, inflammation, and other key disease areas, today announced that multiple key clinical updates for its core asset CS2009 (a PD-1/VEGF/CTLA-4 trispecific antibody) were presented in two posters at the American Society of Clinical Oncology (ASCO) Annual Meeting, covering Phase I/II clinical data in first-line and later-line NSCLC and CRC patients, as well as mature Phase I data from longer follow-up in patients with advanced solid tumors.
