Liposomal irinotecan plus cisplatin/carboplatin as second-line therapy for platinum-sensitive relapsed extensive-stage small cell lung cancer: Interim results of a phase II trial.

e20128 Background: Platinum-sensitive relapsed extensive-stage SCLC represents an unmet medical need, with limited second-line options offering modest efficacy and significant toxicity. Liposomal irinotecan, a topoisomerase I inhibitor with enhanced tumor targeting, may improve outcomes in this setting. This phase II study evaluated the efficacy and safety of liposomal irinotecan combined with cisplatin or carboplatin in patients with platinum-sensitive relapsed extensive-stage SCLC. Methods: This prospective, multicenter, single-arm, exploratory phase II trial enrolled patients with pathologically confirmed extensive-stage SCLC who had progressed ≥6 months after first-line platinum-based chemoradiotherapy (with or without immunotherapy). The study was planned to enroll a total of 24 patients, with an interim analysis scheduled to be conducted following efficacy evaluation of 12 patients. Patients received liposomal irinotecan (70 mg/m 2 IV on days 1 and 15) plus cisplatin (60 mg/m 2 IV on day 1) or carboplatin (AUC=5 IV on day 1) every 4 weeks until disease progression, intolerable toxicity, withdrawal, or investigator decision. The primary endpoint was objective response rate (ORR). Secondary endpoints included disease control rate (DCR), progression-free survival (PFS), overall survival (OS), duration of response (DoR), and safety (incidence and severity of treatment-related adverse events [TRAEs]). Results: Enrollment began in June 2024, and as of December 30, 2025, 15 patients had been enrolled (median age 58 years, 86.7% male, 73.3% with stage IV disease). Most patients (80.0%) had received prior platinum-based therapy combined with immunotherapy or targeted agents. Among 12 efficacy-evaluable patients, the ORR was 41.7% (95% CI: 19.3–68.0%), with 5 partial responses; DCR was 75.0% (95% CI: 46.8–91.1%). Median treatment cycles were 2 months(range: 1–9), and median follow-up was 3.45 months. PFS, OS, and DoR data are immature due to short follow-up. Safety analysis (n=15) showed any-grade TRAEs in 66.7% of patients, with grade 3–4 TRAEs in 46.7%. Common TRAEs included neutropenia (46.7%), diarrhea (26.7%), thrombocytopenia (26.7%), and leukopenia (46.7%). Most TRAEs were manageable with supportive care or dose adjustments (only one dose adjustment due to AE). No treatment-related deaths occurred. Conclusions: Liposomal irinotecan combined with cisplatin/carboplatin demonstrates promising antitumor activity (ORR 41.7%) and a manageable safety profile in platinum-sensitive relapsed extensive-stage SCLC. These interim results support further investigation of this regimen as a potential second-line option. Longer follow-up is needed to assess survival endpoints and durability of response. Clinical trial information: NCT06467786 .