SHANGHAI – October 27, 2026 -- Henlius' serplulimab combined with chemotherapy delivered a median overall survival (OS) of 12.4 months versus 10.2 months for atezolizumab plus chemotherapy in the U.S. ASTRIDE study of first-line extensive-stage small cell lung cancer (ES-SCLC). The company presented the data at the European Society for Medical Oncology (ESMO) Congress 2026.
ASTRIDE shows a numerical OS edge but no formal superiority test
The hazard ratio was 0.82 (95% CI, 0.56-1.20), at a median follow-up of 14.1 months and a data cutoff of February 18, 2026. The trial was descriptive, with no formal hypothesis testing for superiority or noninferiority planned.
One-year OS rates were 52.4% for serplulimab and 41.4% for atezolizumab. Two-year OS rates were 32.2% and 17.6%, respectively. The serplulimab arm had more patients with liver metastasis (49.5% vs 40.0%).
Patients without prior chemotherapy gained 13.4 months median OS on serplulimab
In the 158 intent-to-treat patients with no prior chemotherapy (82 on serplulimab, 76 on atezolizumab), median OS was 13.4 months versus 10.8 months. The hazard ratio in this subgroup was 0.77 (95% CI, 0.50-1.17).
Median progression-free survival by blinded independent central review was 5.4 months with serplulimab and 4.9 months with atezolizumab. Objective response rates were 65.7% and 67.0%, and median duration of response was 4.2 and 4.0 months.
Grade 3 or higher adverse events hit 73.7% of serplulimab patients versus 73.0% on atezolizumab
Treatment-related grade 3 or higher events occurred in 20.2% of serplulimab patients and 25.0% of atezolizumab patients. Immune-related adverse events affected 21.2% and 23.0%.
Trial randomized 201 U.S. patients across 63 sites against the most-used comparator
ASTRIDE ran from 2022 to 2025 and randomized patients 1:1 to serplulimab 300 mg or atezolizumab 1,200 mg, each every three weeks with carboplatin and etoposide. Atezolizumab was chosen because it is the most widely used regimen in U.S. practice. A June 2024 protocol amendment let newly diagnosed patients receive one chemotherapy cycle before randomization, which helped increase accrual.
Black or African American patients made up 5% of enrollment, and Hispanic or Latino patients 4.5%.
Principal investigator links 32% two-year survival to the ASTRUM-005 Phase 3 result
Lead investigator David R. Gandara of the University of California Davis Comprehensive Cancer Center called the results "remarkably consistent" with ASTRUM-005. He noted that the 32% two-year survival rate is identical in both studies.
ASTRUM-005 was a randomized, double-blind Phase 3 trial that enrolled 585 subjects and compared serplulimab with placebo, both combined with chemotherapy, at a 2:1 ratio. It met its primary OS endpoint at interim analysis in December 2021. Only 31.5% of its participants were White, and its sites included Türkiye, Poland, Georgia and China.
Serplulimab is approved in more than 50 countries but holds only U.S. orphan designation
The anti-PD-1 antibody is approved in more than 50 countries and regions across ES-SCLC and other indications. It is reimbursed or publicly covered in more than 10 countries, including the U.K., Germany, Italy and Spain. The U.S. FDA granted it orphan-drug designation for small cell lung cancer in March 2022. The source does not mention a U.S. approval.