Henlius reports median overall survival of 12.4 months with serplulimab versus 10.2 months with atezolizumab in the descriptive ASTRIDE study in ES-SCLC.
Written By: Anamika Koshti, PharmD
Reviewed By: Pharmacally Editorial Team
Shanghai Henlius Biotech reported results from ASTRIDE (NCT05468489), a US bridging study evaluating serplulimab, an anti-PD-1 antibody marketed in Europe as Hetronifly, plus carboplatin and etoposide against atezolizumab plus the same chemotherapy in first-line extensive-stage small cell lung cancer (ES-SCLC). Presented at the European Society for Medical Oncology (ESMO) Congress 2026 on October 26, the results showed numerically longer overall survival (OS) with serplulimab. However, the study was descriptive and was not designed to establish superiority or noninferiority between the regimens.
A US Study to Complement Phase 3 Evidence
Serplulimab’s principal evidence in ES-SCLC comes from ASTRUM-005 (NCT04063163), an international, randomized, double-blind Phase 3 trial involving 585 patients. The study demonstrated a statistically significant OS benefit when serplulimab was added to carboplatin and etoposide, compared with placebo plus chemotherapy. In an extended follow-up analysis, median OS was 15.8 versus 11.1 months.
Because ASTRUM-005 was conducted outside the United States, Henlius initiated ASTRIDE to assess serplulimab in a US patient population against atezolizumab, an established first-line immunotherapy option in US practice. ASTRIDE complements the global Phase 3 evidence rather than independently confirming a survival advantage over the US comparator.
Randomized Design with a Descriptive Analysis
ASTRIDE randomized 201 US patients across 63 sites in a 1:1 ratio to serplulimab plus carboplatin and etoposide or atezolizumab plus the same chemotherapy. Patients continued maintenance immunotherapy after induction treatment until disease progression or another protocol-defined reason for discontinuation.
The protocol was amended in June 2024 to allow eligible patients to receive one chemotherapy cycle before randomization, accommodating the need to begin treatment promptly in this rapidly progressive disease. The primary endpoint was OS. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR) and duration of response (DOR), with response outcomes assessed by blinded independent central review.
At the February 18, 2026 data cutoff, median follow-up was 14.1 months. No formal hypothesis testing for superiority or noninferiority was planned.
Overall Survival Favored Serplulimab Numerically
Median OS was 12.4 months with serplulimab versus 10.2 months with atezolizumab (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.56–1.20). Estimated 12-month OS was 52.4% versus 41.4%, while 24-month OS was 32.2% versus 17.6%, respectively.
The serplulimab group also had a higher proportion of patients with liver metastases at baseline (49.5% versus 40.0%). Although this imbalance provides clinical context, it does not establish why the survival estimates differed.
The two-year OS rate of 32.2% was consistent with the figure reported in ASTRUM-005. This supports the applicability of the earlier trial’s findings to the US study population, but the cross-trial comparison should be interpreted cautiously because the studies differed in design and comparator.
The ASTRIDE OS confidence interval included 1.0. The numerical differences therefore do not establish statistically significant superiority over atezolizumab.
Progression and Response Outcomes Were Similar
Median PFS by blinded independent central review was 5.4 months with serplulimab and 4.9 months with atezolizumab (HR, 0.95; 95% CI, 0.67–1.35). ORR was 65.7% versus 67.0%, and median DOR was 4.2 versus 4.0 months.
These findings indicate broadly similar measured disease-control outcomes. The numerical separation in OS occurred without a corresponding substantial difference in PFS, response rate or response duration. The available results do not establish whether subsequent treatment, patient characteristics, chance or other factors contributed to the OS pattern.
Safety Profiles Were Broadly Comparable
Grade 3 or higher treatment-emergent adverse events occurred in 73.7% of patients receiving serplulimab and 73.0% receiving atezolizumab. Grade 3 or higher events attributed to the study immunotherapy occurred in 20.2% and 25.0%, respectively. Immune-related adverse events were reported in 21.2% versus 23.0%. Henlius reported no new safety signals.
These findings suggest broadly comparable safety profiles, although differences in individual adverse events and treatment discontinuations should be considered alongside the overall rates.
Clinical Implications
ASTRIDE provides additional evidence on serplulimab in US patients with first-line ES-SCLC and complements the survival benefit demonstrated in ASTRUM-005. The numerical OS advantage over atezolizumab is clinically noteworthy, but the descriptive design, confidence interval crossing 1.0 and broadly similar PFS and response outcomes limit conclusions about comparative efficacy.
The findings support further assessment of serplulimab in the US setting. They do not establish superiority over atezolizumab or demonstrate that PD-1 blockade is more effective than PD-L1 blockade in ES-SCLC. The results alone also do not establish the sufficiency or outcome of a US regulatory submission.
Reference
Henlius reports positive results from ASTRIDE U.S. bridging study for serplulimab in combination with chemotherapy for first-line treatment of patients with extensive-stage small cell lung cancer (ES-SCLC), Henlius, 27 October 2026
To Evaluate Efficacy and Safety of Serplulimab + Chemotherapy (Carboplatin- Etoposide) in US Patients With ES-SCLC, ClinicalTrials.gov ID NCT05468489
A Phase III Study to Investigate Efficacy and Safety of HLX10 + Chemotherapy in Patients With ES-SCLC, ClinicalTrials.gov ID NCT04063163
About the Writer
Anamika Koshti (LinkedIn) is a PharmD professional and healthcare writer with interests in clinical research, pharmacovigilance, and evidence-based medicine. She has authored peer-reviewed publications on Alzheimer’s disease and PCOS, presented research at national conferences, and gained hands-on experience in medical content development and clinical data interpretation. She is committed to translating complex medical research into accurate, accessible content for healthcare professionals and patients.