Toripalimab added to etoposide plus cisplatin or carboplatin improved survival in extensive-stage small cell lung cancer.

The 5-year survival rate of patients with ES-SCLC is less than 8%; therefore, more effective treatments are urgently needed. Combinations of immunotherapy with chemotherapy as a first-line treatment for ES-SCLC have generated mixed results [1]. The EXTENTORCH trial (NCT04012606) assessed the clinical efficacy and safety of toripalimab, an anti-PD-1 monoclonal antibody, combined with chemotherapy as a first-line treatment for participants with ES-SCLC. Dr. Ying Liu (Jilin Cancer Hospital, China) presented the initial results [2].

A total of 424 treatment-naive participants with confirmed ES-SCLC were randomly assigned 1:1 to 4–6 cycles of toripalimab plus chemotherapy (etoposide/cisplatin or carboplatin) or placebo plus chemotherapy, followed by maintenance therapy with toripalimab or placebo. The primary endpoint was PFS.

After a median follow-up of 11.8 months, the median PFS for participants in the toripalimab arm was 5.8 months (95% CI, 5.6-6.8) versus 5.6 months (95% CI, 5.5-5.7) for participants in the placebo arm (HR, 0.667; 95% CI, 0.539-0.824; P=0.0002). The PFS rate at 1 year was 18.1% versus 4.9% for the toripalimab and placebo arm, respectively. Median OS in the toripalimab arm was 14.6 months versus 13.3 months in the placebo arm (HR, 0.798; 95% CI, 0.648-0.982; P=0.327). “Whole exome sequencing results showed that the observed improvements in progression-free survival (PFS) and overall survival (OS) were similar irrespective of tumor mutation burden,” said Dr. Liu.

The combination of toripalimab and chemotherapy was generally well tolerated; no difference was observed in the rates of grade 3–5 adverse events (89% in both arms) or discontinuation of treatment (3.2% in both arms).

Overall, the addition of toripalimab to chemotherapy provided significant improvements in PFS and OS for patients with ES-SCLC with an acceptable safety profile.

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