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Addition of PD-1 Inhibitor Serplulimab to Chemotherapy in the First-Line Treatment of Extensive-Stage SCLC


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As reported in JAMA by Cheng et al, an interim analysis of the phase III ASTRUM-005 trial has shown that the addition of the PD-1 inhibitor serplulimab to chemotherapy improved overall survival in the first-line treatment of patients with extensive-stage small cell lung cancer (SCLC).

Study Details

The double-blind trial included 585 patients from sites in China, Georgia, Poland, Russia, Turkey, and Ukraine. They were randomly assigned 2:1 between September 2019 and April 2021 to receive serplulimab at 4.5 mg/kg (n = 389) or placebo (n = 196) every 3 weeks plus etoposide at 100 mg/m2 on days 1 to 3 and carboplatin area under the curve = 5 (up to 750 mg) on day 1 every 3 weeks for up to 12 weeks. The primary endpoint was overall survival; the prespecified significance threshold at the interim analysis was a two-sided P < .012. In total, 67% of patients in the serplulimab group and 71% in the control group were Asian.

Overall Survival

At data cutoff in October 2021 for the interim analysis, median follow-up was 12.3 months (range = 0.2–24.8 months). Median overall survival was 15.4 months (95% confidence interval [CI] = 13.3 months–not evaluable) in the serplulimab group vs 10.9 months (95% CI = 10.0–14.3 months) in the control group (hazard ratio [HR] = 0.63, 95% CI = 0.49–0.82, P < .001).

KEY POINTS

  • The addition of the PD-1 inhibitor serplulimab to chemotherapy significantly improved overall survival at interim analysis.
  • Median overall survival was 15.4 vs 10.9 months.

Median progression-free survival on independent radiology review committee assessment was 5.7 months (95% CI = 5.5–6.9 months) in the serplulimab group vs 4.3 months (95% CI = 4.2–4.5 months) in the placebo group (HR = 0.48, 95% CI = 0.38–0.59). Objective response was observed in 80.2% vs 70.4% of patients, with complete response seen in 0.8% vs 0%. Median response durations were 5.6 vs 3.2 months.

Adverse Events

Treatment-related grade ≥ 3 adverse events occurred in 33.2% of patients in the serplulimab group and in 27.6% of those in the control group; the most common in both groups were decreased neutrophils (14.1% vs 13.8%), decreased white blood cells (8.5% vs 8.7%), and decreased platelets (6.2% vs 8.2%). Treatment was discontinued due to treatment-related adverse events in 4.9% vs 4.1% of patients. Immune-related adverse events of any grade were reported in 37.0% vs 18.4% of patients (grade ≥ 3 in 9.5% vs 5.6%); those more common in the serplulimab group included hypothyroidism (11.6% vs 1.5%) and hyperthyroidism (9.0% vs 3.1%). Death due to adverse events attributed to serplulimab occurred in three patients (0.8%), with causes consisting of acute coronary syndrome, pyrexia, and decreased platelet count. Treatment-related death occurred in one patient in the control group (0.5%) due to thrombocytopenia.

The investigators concluded, “Among patients with previously untreated extensive-stage SCLC, serplulimab plus chemotherapy significantly improved overall survival compared with chemotherapy alone, supporting the use of serplulimab plus chemotherapy as the first-line treatment for this patient population.”

Ying Cheng, MD, of the Department of Oncology, Jilin Cancer Hospital, Changchun, China, is the corresponding author for the JAMA article.

Disclosure: This study was funded by Shanghai Henlius Biotech, Inc. For full disclosures of the study authors, visit jamanetwork.com.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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