CS2009 Achieved Key Clinical Validations for Efficacy and Safety
As of August 2026, updated data further confirmed the favorable safety profile of CS2009 and demonstrated strengthened efficacy across multiple key cohorts compared with the data presented at ASCO in May 2026. With expanded patient enrollment and longer follow-up, improvements were observed in both the objective response rate (ORR) and duration of response (DOR):
Compelling monotherapy efficacy in first-line non-small cell lung cancer (NSCLC)
- At the 30 mg/kg dose level, CS2009 achieved an ORR of 100% and a disease control rate (DCR) of 100% in patients with PD-L1 TPS ≥50%. In the broader PD‑L1 TPS ≥1% population, the ORR was 70.8% and DCR was 91.7%.
Monotherapy efficacy in Immunotherapy (IO)-pretreated NSCLC and IO-nonresponsive "cold tumors" further validates CTLA-4 activity and efficacy
- In second-line NSCLC patients (all previously treated with IO plus chemotherapy), CS2009 monotherapy (30 mg/kg dose level) yielded an ORR of 38.5% and a DCR of 84.6%;
- In patients with heavily pretreated metastatic colorectal cancer (mCRC), CS2009 monotherapy (30 mg/kg dose level) achieved an ORR of 20% and a DCR of 93.3%;
- In patients with heavily pretreated soft tissue sarcoma (STS) and non-clear cell renal cell carcinoma (nccRCC), CS2009 monotherapy delivered ORR of 38.5% and 42.9%, respectively.
CStone will present additional more mature Phase I/II clinical data for CS2009 in patients with advanced NSCLC and mCRC via two rapid oral presentations at ESMO 2026 in October. The Company also expects to reach consensus with global regulatory authorities including the U.S. Food and Drug Administration (FDA) and the Center for Drug Evaluation (CDE) of China National Medical Products Administration (NMPA), on the global Phase III registrational trial protocol in the fourth quarter of 2026.
Pralsetinib Delivers Strong Sales Growth
Following its effective inclusion in the National Reimbursement Drug List (NRDL) on January 1, 2026, pralsetinib’s in-market sales volume increased by almost 500% year-over-year in the seven‑month period ending July 2026.
Solid Cash Position
As of June 30, 2026, cash and cash equivalents and time deposits totaled RMB1,560.2 million.
SUZHOU, China, Aug. 27, 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 its 2026 interim results and recent business highlights.
Dr. Jason Yang, CEO, President of R&D, and Executive Director at CStone, commented, "In the first half of 2026, CStone entered a pivotal stage of transition from innovation-driven accumulation to global value realization.
Our lead asset, CS2009, continues to advance rapidly through global clinical development. To date, we have accumulated clinical data from more than 300 patients, consistently demonstrating three key clinical validations: first, proof of safety; second, multidimensional confirmation of CTLA‑4 target activity and efficacy, evidenced by pharmacodynamic biomarkers and clinical activity in "cold tumors" and IO‑pretreated NSCLC; and third, broad‑spectrum and highly competitive antitumor efficacy across multiple tumor types. The most recent data show that CS2009’s antitumor activity continues to deepen and strengthen with longer follow-up, exhibiting particularly competitive efficacy and a well-tolerated safety profile in key patient populations, including NSCLC and mCRC. These robust data provide strong support for the upcoming global Phase III registrational trials. We look forward to presenting additional more mature clinical data on CS2009 in oral presentations at the ESMO Congress this October.
Beyond CS2009, other Pipeline 2.0 candidates are also progressing steadily toward clinical stage. CS5007, built on our proprietary ADC platform, has initiated a global Phase I clinical trial in both China and Australia. In addition, more than ten early-stage programs spanning next-generation ADCs, immunology & inflammation and other areas are advancing smoothly. The successive entry of these differentiated innovative assets into clinical development will serve as a critical driver for the Company’s sustained growth and global expansion.
On the commercial front, our three key products, sugemalimab, pralsetinib, and avapritinib, continued to achieve breakthroughs across domestic and international markets, contributing significant momentum to revenue growth. Notably, following pralsetinib’s first-time inclusion in the NRDL earlier this year, its in-market sales volume increased by almost 500% year-over-year during the first seven months of 2026, making it the primary driver of the Company’s revenue growth in the first half of 2026.
Looking ahead, CStone will focus on advancing the clinical value of its Pipeline 2.0 assets and actively pursue global partnerships to accelerate their development. Concurrently, the Company will continue to maximize the commercial potential of its marketed products through strategic partnerships and resource integration. Our goal is to foster a sustainable growth model where R&D and commercialization reinforce each other, creating a virtuous cycle between innovation and business operations."
Business Highlights
For the six months ended June 30, 2026 and up to the date of this results announcement, CStone made significant progress across both its proprietary Pipeline 2.0 portfolio and its commercial franchise, advancing the Company’s strategy to build a fully integrated, globally competitive biopharmaceutical company.
Clinical Stage Core Asset
CS2009, PD-1/VEGF/CTLA-4 trispecific antibody
- Accelerating global clinical development toward Phase III registrational trials by year end
The ongoing global Phase I/II trial has enrolled more than 300 patients across China and Australia, with U.S. Investigational New Drug (IND) clearance obtained in February 2026.
CStone plans to initiate the first wave of global Phase III multi-regional clinical trials (MRCTs) for CS2009 by the end of 2026. Planned registrational studies include first-line non-small cell lung cancer (NSCLC) in combination with chemotherapy (versus pembrolizumab plus chemotherapy), and first-line mCRC in combination with chemotherapy (versus bevacizumab plus chemotherapy), with additional registrational studies planned for 2027 and following years.
- CS2009 validates its potential as a next-generation I/O backbone
At the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, CStone presented comprehensive Phase I/II data from the ongoing global multicenter trial. As of the data cutoff date of August 2026, updated monotherapy efficacy data from the ongoing global Phase I/II trial of CS2009, reflecting a longer follow-up and larger sample size than the ASCO 2026 presentation continued to demonstrate robust and deepening antitumor activity across multiple tumor types. Three important key clinical validations are achieved from over 300 patient data:
- Proof of safety
Across all dose levels, no dose-limiting toxicities (DLTs) were observed, and the maximum tolerated dose (MTD) was not reached. In the ASCO 2026, the incidence of Grade 3 treatment-related adverse events (TRAEs) and immune-related adverse events (irAEs) were 24.6% and 12.7%, respectively. Notably, the incidence of Grade 3 VEGF-related TRAEs was only 5.1%. No excessive toxicities typically associated with CTLA-4/PD-(L)1 combinations were observed. As of August 2026, the safety profile of CS2009 remained consistent with that presented at the 2026 ASCO Annual Meeting, with no new safety signals identified.
- Proof of CTLA-4 activities and efficacy
Dose-dependent upregulation of ICOS on CD4+ T cells was observed as a pharmacodynamic biomarker of CTLA-4 blockade. Activity was also seen in "cold tumor" not sensitive to PD-(L)1 mAb:
- Later-line monotherapy for mCRC (30 mg/kg): the objective response rate (ORR) was 20.0% (3/15) and the disease control rate (DCR) was 93.3% (14/15).
- Later-line monotherapy for soft-tissue sarcoma (STS): the ORR was 38.5% (5/13) and the DCR was 69.2% (9/13). Later-line monotherapy for non-clear cell renal cell carcinoma (nccRCC): the ORR was 42.9% (3/7) and the DCR was 100.0% (7/7).
- Promising anti-tumor activity in later-line post immuno-oncology (IO) NSCLC monotherapy: ORR was 23.8% (5/21), DCR was 61.9% (13/21). Among patients who had previously received immunotherapy plus platinum-based chemotherapy (n=13), ORR was 38.5% (5/13) and DCR was 84.6% (11/13).
- Proof of broad efficacy
Monotherapy and chemo-combination activity in first-line and later-line NSCLC:
- First-line NSCLC monotherapy (PD-L1 tumor proportion score [TPS] ≥1%; enrollment completed): ORR of 61.7% (29/47) and DCR of 93.6% (44/47), including ORR of 70.8% (17/24), DCR 91.7% (22/24) in patients treated at 30 mg/kg; in the PD-L1 TPS ≥50% group (n=24), ORR was 83.3% (20/24) and DCR was 95.8% (23/24) (versus ORR of 81.3% [13/16] at the 2026 ASCO cutoff), including ORR of 100.0% (11/11) and DCR of 100.0% (11/11) in patients treated at 30 mg/kg. After median follow up of 6 months, median progression-free survival (PFS) and DOR have not been reached.
- Second-line or later NSCLC monotherapy (30 mg/kg): ORR of 28.0% (7/25) and DCR of 60.0% (15/25), with a 6-month DOR rate of 83.3% (versus ORR of 24.0% and a 6-month DOR rate of 80.0% at the 2026 ASCO cutoff). Across all evaluated dose levels (n=54), ORR was 16.7% (9/54) and DCR was 68.5% (37/54), with a 6-month DOR rate of 87.5% (versus 85.7% at the 2026 ASCO cutoff).
- Later-line NSCLC (second/third-line combination therapy, n=6): ORR of 66.7% (4/6), DCR of 100.0% (6/6). Data are as of the 2026 ASCO data cutoff and will be updated at ESMO 2026.
- First-line squamous NSCLC combination therapy (PD-L1-low/negative, TPS ≤5%, n=8): ORR of 75.0% (6/8), DCR of 100.0% (8/8); notably, the ORR reached 100.0% (4/4) in the PD-L1-negative subgroup. Data are as of the ASCO 2026 data cutoff and will be updated at ESMO 2026.
Robust Chemo-combo efficacy in the first-line mCRC, mostly proficient mismatch repair or microsatellite stable (pMMR/MSS):
- First-line mCRC (with XELOX, n=6): ORR of 66.7% (4/6), DCR of 100.0% (6/6). Data as of 2026 ASCO cutoff, will be updated at ESMO 2026.
Promising monotherapy activity observed in metastatic castration-resistant prostate cancer (mCRPC), ovarian cancer, triple-negative breast cancer, gastric cancer, esophageal cancer, as well as STS and nccRCC.
- Upcoming two oral presentations of CS2009 at ESMO 2026
The clinical research results of CS2009 have been accepted for two Rapid Oral presentations at the 2026 European Society for Medical Oncology (ESMO) Congress. The presentations will feature Phase I/II clinical data of CS2009 in patients with advanced NSCLC and mCRC.
Other Clinical Stage Asset
CS5007, EGFR/HER3 ADC
- Global Phase I trial initiated in China and Australia
The Company initiated the Phase I first-in-human study in June 2026. This trial consists of dose-escalation and dose-expansion cohorts evaluating CS5007 as a monotherapy in patients with advanced solid tumors, and will be conducted concurrently in Australia and China. CStone presented preclinical data for CS5007 at the 2026 American Association for Cancer Research (AACR) Annual Meeting, further supporting its broad-spectrum anti-tumor potential.
Commercial Products
CEJEMLY® (sugemalimab), anti-PD-L1 antibody
- Global regulatory and scientific recognition
Following the initial marketing authorizations of sugemalimab in the European Union (EU) and the United Kingdom (U.K.) for Stage IV NSCLC, sugemalimab received additional approvals in the EU in November 2025 and subsequently in the U.K. in February 2026 as monotherapy for adults with unresectable Stage III NSCLC whose disease has not progressed following platinum-based chemoradiotherapy (CRT). Meanwhile, marketing authorization applications for sugemalimab have either been approved or are under active review in nearly 30 countries worldwide.
In March 2026, CEJEMLY® (sugemalimab) was included in the ESMO Early and Locally Advanced NSCLC Living Guideline. Sugemalimab received a Level [I, A] recommendation for consolidation therapy in patients with unresectable Stage III NSCLC who have not progressed after concurrent or sequential chemoradiotherapy.
- Secured fifth international commercial partnership
In June 2026, CStone entered into an exclusive commercialization agreement with Arrotex Pharmaceuticals Pty Ltd (Arrotex), Australia’s largest privately owned pharmaceutical company with established oncology commercialization capabilities and distribution infrastructure across Australia and New Zealand. This milestone expands sugemalimab’s global commercialization network to five strategic partnerships, covering more than 60 countries and regions across Europe, the Middle East and Africa, Latin America, and Oceania.
Pralsetinib capsules, RET inhibitor
- NRDL inclusion and accelerated commercial growth
Following the inclusion of pralsetinib capsules (100 mg) in China’s NRDL in late 2025, effective January 1, 2026, patient access has improved significantly. In the seven‑month period ending July 2026, pralsetinib’s in-market sales volume increased by almost 500% year-over-year.
- Localized manufacturing approval supporting commercial scalability
Following the approval by China’s NMPA of the manufacturing localization application for pralsetinib capsules (100 mg), the first batch of locally-manufactured pralsetinib was released in China in 2026.
Preclinical/IND-enabling Stage Programs
A balanced, differentiated early-stage portfolio spanning oncology and immunology/inflammation
CStone’s preclinical Pipeline 2.0 comprises innovative candidates across multispecific antibodies, ADCs and other next-generation modalities, with potential first-in-class (FIC) or best-in-class (BIC) opportunities spanning oncology, immunology, inflammation and other high-value therapeutic areas.
The Company’s proprietary ADC platform incorporates optimized linker technologies designed to enable tumor-selective payload release and supports multiple Pipeline 2.0 ADC candidates, including CS5007 (EGFR and HER3 bispecific ADC), CS5006 (ITGB4 ADC), CS5008 (DLL3 and SSTR2 bispecific ADC), etc. The Company is also exploring next-generation ADC technologies, including dual-payload ADCs (e.g., CS5009, a B7H3/PD-L1 bispecific dual-payload ADC, and CS5010, a HER2-targeting dual-payload ADC) and novel-payload ADCs (e.g., CS5012, a HER2-targeting novel-payload ADC). In April 2026, CStone presented preclinical data for CS5007, CS5006 and CS5008 at the 2026 AACR Annual Meeting, highlighting the breadth and differentiation of its next-generation ADC pipeline.
Beyond oncology, CStone has expanded Pipeline 2.0 into immunology and inflammation by leveraging its proprietary multispecific antibody platform. The Company has developed CS2015 (OX40L/TSLP bispecific antibody) targeting Type 2 inflammatory diseases, CS2013 (BAFF/APRIL bispecific antibody) targeting B cell-mediated autoimmune diseases, CS2016 (TL1A/α4β7 bispecific antibody), and CS1016 (PD-1 agonist antibody).
Future and Outlook
Our mission is to deliver transformative therapies through scientific excellence and technological innovation, making high-quality treatments accessible worldwide to benefit patients and their families.
We reaffirm our commitment to advancing a robust and differentiated pipeline by prioritizing internal discovery capabilities and sustained R&D investments, while executing strategic partnerships to unlock the global value of our in-market products. Key catalysts for the second half of 2026 include:
Clinical milestones
- Accelerate global development of CS2009 by advancing interactions with global regulatory authorities, including the U.S. FDA and the CDE of NMPA, on Phase III registrational trial design, with the first wave of global Phase III MRCTs planned to be initiated by the end of 2026, while continuing to pursue global partnerships.
- Advance clinical development of CS5007 (EGFR/HER3 bispecific ADC), CS5006 (ITGB4 ADC), CS5008 (SSTR2/DLL3 ADC) and other early-stage candidates.
Innovation and technology
- Further strengthen proprietary technology platforms, including multi-specific antibody and next-generation ADC technologies, to support sustained expansion of the preclinical pipeline.
- Present key clinical data, including updated CS2009 data, at major international scientific conferences, including two Rapid Oral presentations of CS2009 Phase I/II data at the 2026 ESMO Congress.
Financial Highlights
International Financial Reporting Standards (IFRS) Measures:
Revenue was RMB205.1 million for the six months ended June 30, 2026. The revenue is composed of RMB183.2 million from sales of pharmaceutical products (avapritinib, pralsetinib and sugemalimab), RMB6.9 million from license fee income and RMB15.0 million from royalty income of sugemalimab. The substantial revenue growth was primarily driven by a significant increase in sales of pharmaceutical products, particularly pralsetinib, following its successful inclusion in the NRDL effective from January 2026, which led to a marked sales ramp-up.
Cost of revenue was RMB110.9 million for the six months ended June 30, 2026.
Research and development expenses were RMB205.5 million for the six months ended June 30, 2026, primarily due to increased costs for clinical trials.
Administrative expenses were RMB51.3 million for the six months ended June 30, 2026.
Selling and marketing expenses were RMB73.1 million for the six months ended June 30,2026.
Loss for the period was RMB252.3 million for the six months ended June 30, 2026.
Cash and cash equivalents and time deposits were RMB1,560.2 million as of June 30, 2026.
Non-International Financial Reporting Standards (Non-IFRS) Measures:
Research and development expenses excluding the share-based payment expenses were RMB193.4 million for the six months ended June 30, 2026, primarily due to increased costs for clinical trials.
Administrative and selling and marketing expenses excluding the share-based payment expenses were RMB115.2 million for the six months ended June 30, 2026.
Loss for the period excluding the share-based payment expenses was RMB230.9 million for the six months ended June 30, 2026.
2026 Interim Results Conference Call
The Company will host its 2026 Interim results earnings call at 9:00 a.m. (Beijing Time) on Friday August 28, 2026. Please register for the conference in advance through the link: https://s.comein.cn/nv9vt1dz .
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, immunology, 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 21 new drug applications covering 9 indications. The company’s pipeline is balanced by 13 promising innovative candidates, featuring antibody-drug conjugates (ADCs), mono-/multi-specific 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.
Forward-looking statements
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