Addition of serplulimab to chemotherapy extends OS in small cell lung cancer
The addition of serplulimab to chemotherapy extended OS among patients with previously untreated extensive-stage small cell lung cancer, according to randomized phase 3 study results.
The findings support this combination as first-line treatment for this subgroup, investigators concluded.
Small cell lung cancer, the most aggressive subtype of the malignancy, accounts for approximately 15% of lung cancer cases. Most patients present with extensive-stage disease, and only about 7% of patients survive 5 years after diagnosis.
The long-time standard first-line treatment — platinum chemotherapy plus etoposide — conferred median OS of about 10 months.
The combination of PD-1 inhibitors and chemotherapy has altered the approach to first-line treatment of extensive-stage small cell lung cancer.
However, the potential benefit of adding serplulimab (Hansizhuang, Shanghai Henlius Biotech) — a novel anti-PD-1 antibody — to chemotherapy for this population had not been established.
Ying Cheng, MD, of the department of oncology at Jilin Cancer Hospital in China, and colleagues conducted the international, double-blind ASTRUM-005 trial to determine whether adding serplulimab to first-line therapy improved outcomes for patients with extensive-stage small cell lung cancer.
The analysis included 585 patients (median age, 61.1 years; 82.2% men) treated at 114 hospital sites in six countries. No study participants had received systemic therapy.
Researchers randomly assigned 389 patients to 4.5 mg/kg serplulimab via IV every 3 weeks, plus IV carboplatin and etoposide every 3 weeks for up to 12 weeks. The other 196 received placebo plus chemotherapy.
OS served as the primary endpoint. Secondary outcomes included PFS and adverse events.
Less than half (42.1%) of study participants completed the trial; the majority (79.5%) discontinued study treatment.
After median follow-up of 12.3 months (range, 0.2-24.8), results showed a statistically significant improvement in OS in the serplulimab group (median, 15.4 months vs. 10.9 months; HR = 0.63; 95% CI, 0.49-0.82).
A higher percentage of serplulimab-treated patients remained alive at 1 year (60.7% vs. 47.8%) and 2 years (43.1% vs. 7.9%).
Researchers also reported longer median PFS in the serplulimab group (5.7 months vs. 4.3 months; HR = 0.48; 95% CI, 0.38-0.59).
A comparable percentage of patients in the serplulimab-chemotherapy and chemotherapy alone groups experienced treatment-related adverse events (any grade, 69.9% vs. 56.1%; grade 3 or higher, 33.2% vs. 27.6%). The most common grade 3 or higher events included decreased neutrophil account (14.1% for serplulimab vs. 13.8% for placebo), decreased white blood cell count (8.5% vs. 8.7%), decreased platelet count (6.2% vs. 8.2%) and anemia (5.4% vs. 5.6%).
Treatment-related adverse events led to treatment discontinuation for 4.9% of patients assigned serplulimab and 4.1% of those assigned placebo.
Three patients (0.8%) died of adverse events attributed to serplulimab. These included one case each of acute coronary syndrome, pyrexia and decreased platelet count.
A higher percentage of serplulimab-treated patients experienced immune-related adverse events (any grade, 37% vs. 18.4%; grade 3 or higher, 9.5% vs. 5.6%).
Researchers acknowledged study limitations, including lack of a head-to-head comparison between serplulimab and other PD-L1 inhibitors, the limited number of study participants with brain metastases and the short follow-up duration.
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