• Pioneering a new chemo-sparring regimen: The world’s first chemo-free perioperative regimen for gastric cancer, combined with adjuvant mono-immunotherapy, precisely targeting patients with PD-L1 CPS ≥5

• Robust efficacy benefits:   INV-assessed EFS, the primary endpoint, showed a significant improvement. Median EFS by BICR was also significantly prolonged in the serplulimab group (NR vs. 52.0 months; HR=0.67), translating into a 33% reduction in recurrence risk. The pCR rate reached 21.6% vs. 6.4%, more than tripling that of the control group.

• Favorable safety profile: Grade ≥3 TRAEs (46.6% vs. 58.5%) and treatment discontinuation due to TRAEs (6.5% vs. 10.5%) were both lower with serplulimab than with placebo, supporting better tolerability and a favorable efficacy–safety profile.

Shanghai, China, June 2, 2026 — Henlius (2696.HK) announced that data from ASTRUM-006, a Phase 3 clinical study of its self-developed novel anti–PD-1 monoclonal antibody HANSIZHUANG(serplulimab, trade name in Europe: Hetronifly®) as neoadjuvant/adjuvant treatment for gastric cancer, were formally presented for the first time in an oral presentation at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published online in The Lancet (IF: 88.5), gaining recognition from two of the world’s most prestigious academic platforms. The study was led by Professors Jiafu Ji and Lin Shen from Peking University Cancer Hospital. Against the backdrop of persistently high recurrence rates in locally advanced gastric cancer and the substantial toxicities associated with conventional chemotherapy, ASTRUM-006 has established a new perioperative treatment approach for patients with PD-L1–positive resectable gastric cancer, enabling a postoperative chemotherapy-free strategy with immunotherapy alone, supported by compelling efficacy and a more favorable safety and tolerability profile.

Professor Lin Shen from Beijing Cancer Hospital, a leading principal investigator of the ASTRUM-006 study, stated: “ASTRUM-006 is the first study worldwide to validate the chemotherapy-free immunotherapy regimen for postoperative gastric cancer treatment. This regimen accurately identifies patients who can benefit from immunotherapy and optimizes the treatment strategy. It delivers a milestone improvement in survival outcomes with outstanding safety and tolerability. The findings have been published in The Lancet and presented at ASCO. We hope this innovative regimen with superior efficacy and reduced toxicity can be rapidly adopted in clinical settings to improve patients' survival and treatment experience."

Broad Efficacy Benefits with Breakthrough Improvements in EFS and pCR

According to the latest GLOBOCAN data, there were approximately 969,000 new cases of gastric cancer and 660,000 deaths worldwide in 2022, ranking fifth among all cancers in both incidence and mortality.¹ At present, curative surgery remains the mainstay of treatment for gastric cancer, while optimization of perioperative treatment strategies (neoadjuvant/adjuvant therapy) has become critical to improving long-term survival outcomes.² Although chemotherapy remains the current standard perioperative treatment for gastric cancer, the traditional full-course chemotherapy approach is still associated with a relatively high risk of recurrence and considerable toxicity, underscoring the urgent clinical need for more precise and effective treatment options.

ASTRUM-006 is a randomized, double-blind, multicenter Phase 3 study designed to evaluate the efficacy and safety of serplulimab plus chemotherapy versus placebo plus chemotherapy as neoadjuvant/adjuvant treatment for gastric cancer. The study enrolled patients with PD-L1–positive (PD-L1 CPS ≥5), histologically confirmed, previously untreated, and resectable gastric cancer or gastroesophageal junction (GEJ) adenocarcinoma. Patients were randomized in a 1:1 ratio to receive three cycles of neoadjuvant intravenous serplulimab (4.5 mg/kg) or placebo in combination with S-1 plus oxaliplatin (SOX), a standard perioperative chemotherapy regimen for gastric cancer in Asia. After surgery, patients continued with either adjuvant serplulimab monotherapy (for up to 17 cycles) or adjuvant chemotherapy (for up to 5 cycles), administered every 3 weeks (Q3W).

The primary endpoint was investigator-assessed event-free survival (EFS). Secondary endpoints included median EFS as assessed by blinded independent central review (BICR), pathological complete response (pCR) as assessed by investigators, and other key safety measures.

As of the data cutoff date of August 19, 2025, a total of 588 patients were enrolled in the intention-to-treat (ITT) population across 57 clinical centers in China and randomized 1:1 to the serplulimab group (n=292) or the placebo group (n=296). The median follow-up was 35.9 months. Baseline demographic and disease characteristics were well balanced and comparable between the two groups. The overall study population had relatively advanced disease at enrollment, with T4 primary tumors accounting for 60.6% and 60.8% of patients in the serplulimab and placebo groups, respectively. In terms of performance status, patients with an ECOG PS score of 1 comprised 46.6% of the serplulimab group and 47.0% of the placebo group. Overall, the baseline characteristics of the enrolled population were highly consistent with the real-world clinical profile of patients with locally advanced gastric cancer.

The study met its primary endpoint, with investigator-assessed event-free survival (EFS) showing a significant improvement in the serplulimab group. The median EFS was not reached in the serplulimab group, compared with 35.9 months in the control group (HR=0.73; 95% CI, 0.56–0.94; p=0.015), demonstrating a statistically significant difference. The benefit was further reinforced by BICR. Median EFS was also not reached in the serplulimab group versus 52.0 months in the control group (HR=0.67; 95% CI, 0.50–0.89; p=0.0061), corresponding to a 33% reduction in the risk of recurrence, disease progression, or death, further confirming the robustness of the efficacy findings.

In terms of pathological response, the pCR rate in the serplulimab group reached 21.6%, more than tripling that observed in the placebo group (6.4%), with a marked between-group difference (OR=3.95), indicating a substantially greater depth of tumor regression. Consistent benefit was also observed across subgroups defined by age, sex, performance status, tumor stage, Helicobacter pylori infection status, and PD-L1 expression levels. Overall survival (OS) data remain immature and follow-up is ongoing. Longer-term survival outcomes will be further evaluated as additional data become available.

Improved Efficacy with Reduced Toxicity: A Chemo-Free Approach Highlights Safety and Tolerability Advantages

ASTRUM-006 is the first study in the perioperative treatment of gastric cancer to demonstrate that a chemotherapy-free approach—consisting of neoadjuvant immunotherapy plus chemotherapy followed by adjuvant immunotherapy alone—can deliver significantly improved efficacy while substantially reducing the toxicities associated with conventional full-course chemotherapy, thereby achieving dual benefits in both efficacy and safety.

According to the overall safety data, compared with the placebo group, the serplulimab-based regimen not only improved efficacy but also significantly reduced treatment-related toxicity, with broad improvements across key safety endpoints. The incidence of grade ≥3 treatment-related adverse events (TRAEs) was 46.6% in the serplulimab group, markedly lower than 58.5% in the control group. The rate of treatment discontinuation due to TRAEs was also substantially lower in the serplulimab group (6.5% vs. 10.5%), indicating a meaningfully reduced risk of treatment interruption and further supporting the manageable safety profile and long-term treatment potential of serplulimab. In addition, detailed data published in The Lancet showed that during the adjuvant treatment phase, the incidence of grade ≥3 TRAEs was significantly lower in the serplulimab group than in the placebo group (16% vs. 34%), as was the incidence of TRAEs leading to permanent discontinuation of any study treatment (4% vs. 8%).

In the serplulimab group, patients received adjuvant immunotherapy alone after surgery, eliminating the need for conventional adjuvant chemotherapy and fundamentally reducing severe chemotherapy-related toxicities such as myelosuppression (including neutropenia, thrombocytopenia, and decreased white blood cell count), as well as nausea and vomiting. Meanwhile, immune-related adverse events, such as hypothyroidism, were predominantly mild to moderate in severity, contributing to better tolerability and improved quality of life for patients. This streamlined and efficient perioperative strategy addresses the long-standing challenges of substantial chemotherapy-related toxicity and poor treatment adherence, offering patients with PD-L1–positive gastric cancer a more favorable long-term treatment option.

The success of ASTRUM-006 marks a new milestone of high efficiency and low toxicity in the perioperative therapy of gastric cancer, with the potential to redefine global clinical diagnosis and treatment standards. Based on the positive data from the ASTRUM-006 study, in December 2025, the New Drug Application (NDA) for serplulimab combined with platinum-based chemotherapy as neoadjuvant treatment, followed by adjuvant treatment after surgery, for PD-L1 positive, operable gastric cancer patients, was accepted by the National Medical Products Administration (NMPA) and granted Priority Review. Previously, in November 2025, serplulimab was granted Breakthrough Therapy Designation by the CDE, becoming the first drug in the field of perioperative treatment for gastric cancer to receive this recognition. In April 2026, the perioperative gastric cancer regimen of serplulimab was included for the first time in the CSCO Clinical Guidelines for Gastric Cancer (2026 Edition).

Differentiated Mechanism, Accelerating Global Expansion

Serplulimab is the world’s first and by far the only anti-PD-1 mAb to achieve success in a Phase 3 registrational study for perioperative gastric cancer and the first anti-PD-1 mAb approved for the first-line treatment of SCLC*. Preclinical studies have proven that serplulimab not only induces stronger PD-1 internalization—reducing PD-1 receptor presence on T cells for rapid and potent immune activation³—but also minimizes PD-1-mediated recruitment of the co-stimulatory molecule CD28, thereby preserving CD28 signaling,^4-6 enhancing downstream AKT activity,⁷ and promoting sustained T-cell activation. Based on this differentiated mechanism, serplulimab has established a solid therapeutic advantage in the first-line treatment of high-incidence cancers such as lung cancer and gastrointestinal cancers. It has been approved for the treatment of squamous non-small cell lung cancer (sqNSCLC), extensive-stage small cell lung cancer (ES-SCLC), ESCC, and non-squamous non-small cell lung cancer (nsqNSCLC)**. Up to date, it has been approved in 50 countries and regions including China, the United Kingdom, the European Union, Singapore, India, Switzerland, and Peru, covering nearly half of the global population and demonstrating extremely broad global application scenarios. Moreover, to date, serplulimab has been included in reimbursement or public healthcare coverage systems in 10 countries, including Austria, Denmark, Germany, Ireland, Italy, Spain, and Sweden, thereby gaining access to mainstream healthcare systems in these markets and continuously enhancing its clinical value, commercial potential, and long-term accessibility.

The simultaneous presentation of ASTRUM-006 at ASCO and publication in The Lancet not only highlights the growing global leadership of China’s gastric cancer clinical research, but also breaks through the long-standing limitations of conventional perioperative chemotherapy in gastric cancer, establishing a new treatment paradigm characterized by precise patient selection, improved efficacy, lower toxicity, and a more streamlined regimen. With future regulatory approvals and broader clinical adoption, this serplulimab-based perioperative strategy is poised to reshape the treatment landscape for gastric cancer and benefit a broad population of patients with resectable gastric cancer.

*As of June 2, 2026.

**Approved indications may vary by country or region. Please refer to the announcements issued by the relevant local health authorities for approved indications in each market.

References