The Lancet Publishes Landmark Phase III Results of Serplulimab for Perioperative Gastric Cancer Treatment

Background

Gastric cancer is among the most common malignancies globally, with elevated incidence rates in East Asia. For individuals with locally advanced resectable gastric or gastro-oesophageal junction adenocarcinoma, perioperative chemotherapy has served as a standard of care, though recurrence rates indicate scope for therapeutic advancement.

The phase 3 ASTRUM-006 trial, led by Prof. Jiafu Ji and Prof. Lin Shen from Peking University Cancer Hospital, assessed the addition of the PD-1 inhibitor serplulimab to perioperative treatment in patients with PD-L1 combined positive score of 5 or higher. The primary results were published online in The Lancet on 1 June 2026, with simultaneous presentation at the 2026 ASCO Annual Meeting. The randomised, double-blind, multicentre study was conducted across centres in China and Thailand.

What was achieved

A total of 588 patients were enrolled. Participants received three cycles of neoadjuvant serplulimab (4.5 mg/kg intravenously) or placebo plus SOX chemotherapy (oxaliplatin 130 mg/m² on day 1 and S-1 orally days 1-14 of a 21-day cycle), followed by surgery. In the experimental arm, adjuvant therapy consisted of serplulimab monotherapy for up to 17 cycles; the control arm received five cycles of adjuvant SOX.

The trial met its primary endpoint of investigator-assessed event-free survival. In the PD-L1 CPS ≥10 population, median event-free survival was not reached in the serplulimab group versus 42.0 months in the placebo group (hazard ratio 0.65, 95% CI 0.47-0.90; p=0.0082) at a median follow-up of 42.7 months. In the intention-to-treat population, median event-free survival was not reached versus 35.9 months (hazard ratio 0.73, 95% CI 0.56-0.94; p=0.015) at 35.9 months follow-up. Pathological complete response rate was 21.6% in the serplulimab arm versus 6.4% in the control arm. Grade ≥3 treatment-related adverse events occurred in 47% versus 59% of patients, with treatment discontinuation due to adverse events in 7% versus 11%. Overall survival data remained immature at the time of reporting.

How it works

Serplulimab is a monoclonal antibody targeting PD-1, a checkpoint protein on T cells of the immune system. Many cancer cells express PD-L1, which binds PD-1 and suppresses immune attack. By blocking this interaction, serplulimab helps restore the ability of T cells to recognise and eliminate tumour cells.

In the ASTRUM-006 regimen, serplulimab is combined with SOX chemotherapy before surgery (neoadjuvant phase) to reduce tumour burden and improve the chances of complete resection with a strong pathological response. Following surgical removal of the tumour, patients in the experimental group transition to serplulimab monotherapy as adjuvant treatment. This approach limits additional postoperative chemotherapy exposure compared with the standard arm, aiming to sustain anti-tumour immune activity while reducing cumulative chemotherapy-related side effects.

What it means for international patients

The ASTRUM-006 results represent the first phase 3 demonstration of event-free survival benefit with a PD-1 inhibitor in the perioperative setting for PD-L1-positive resectable gastric or gastro-oesophageal junction adenocarcinoma, including a chemotherapy-sparing adjuvant component. Conducted with leadership from Peking University Cancer Hospital, the findings add to the global evidence base on immuno-oncology strategies for gastric cancer.

International patients with matching tumour characteristics may consider these data when evaluating treatment pathways. The hospital provides VIP services supporting specialised oncology care. Patients should contact the hospital directly to confirm individual eligibility for therapies, trial-related protocols if ongoing, current clinical availability, and specifics of international or VIP patient support.

About the hospital

Peking University Cancer Hospital, also known as Beijing Cancer Hospital, is located at 52 Fucheng Road, Haidian District, Beijing. Founded in 1976, it is a Grade 3A tertiary specialised oncology hospital affiliated with Peking University. It incorporates the Beijing Institute for Cancer Research and Peking University School of Oncology, integrating clinical service, scientific research, education and cancer prevention.

The hospital maintains 36 clinical departments, research laboratories and serves as Beijing’s designated centre for cancer registration and statistics. It has particular recognised expertise in gastrointestinal cancers including gastric cancer, employing multidisciplinary teams and participating in high-impact clinical trials. It recorded high annual volumes of patient care, with approximately 848 beds in recent reporting. VIP wards provide dedicated perioperative and specialised care environments.