429P Real-world (RW) effectiveness and safety of lurbinectedin for previously treated small cell lung cancer (SCLC): Jazz EMERGE 402

Background: Extensive-stage small cell lung cancer (ES-SCLC) has limited therapeutic choices.Chemotherapy-induced myelosuppression (CIM) and immunosuppression remain clinical challenges.Envafolimab, a subcutaneous anti-PD-L1 mAb approved in MSI-H/dMMR advanced solid tumors, works in lung cancer.Trilaciclib, a CDK4/6 inhibitor, may cut CIM and boost anti-tumor effects with chemo-IO.Methods: This phase II trial (NCT06698965) enrolled 52 newly diagnosed ES-SCLC patients, randomized 1:1 to the experimental group (trilaciclib 240 mg/m 2 + envafolimab + EC) or control group (envafolimab + EC).Envafolimab (300 mg D1, Q3W) and EC (etoposide 80-100 mg/m 2 D1-3, carboplatin AUC=5 D1, Q3W) were administered for 6 cycles, followed by maintenance therapy with envafolimab for up to 2 years.Results: As of Dec 1, 2025, all 52 patients (26 per group) completed treatment with balanced baseline characteristics.After a median follow-up of 157.5 days, the control group achieved a median PFS of 5.86 months, consistent with the PFS data of approved chemo-immunotherapy regimens for first-line ES-SCLC, while the experimental group demonstrated significantly longer median PFS (8.40 months; HR=0.39, 95% CI: 0.17-0.91,p=0.012).The experimental group had significantly lower incidences of grade 3 neutropenia (26.9% vs 61.5%), grade 4 hematologic toxicity (3.8% vs 30.8%), and grade 3 leukopenia, thrombocytopenia, and anemia compared with the control group (all p<0.05).Lower myelosuppression incidence was also observed in the experimental group across age and brain metastasis subgroups.Exploratory analysis showed that only the experimental group had significant decreases in serum IL-6 (cycle 4 vs baseline, p<0.05) and IFN (cycle 5 vs baseline, p<0.05). Conclusions:Trilaciclib combined with envafolimab plus EC significantly reduces severe CIM and improves PFS in first-line ES-SCLC.The regimen has a manageable safety profile with consistent benefits across patient subgroups.The reduction in proinflammatory cytokines may support its immune-modulatory role.Ongoing follow-up will confirm long-term OS benefits.