Background: Relapsed SCLC is a difficult-to-treat disease. A considerable number of SCLC patients are elderly with associated fragility and numerous comorbidities. Accelerated approval from the US FDA of lurbinectedin (Zepzelca) 3.2 mg/m² q3wk as second-line therapy in metastatic small cell lung cancer (SCLC) was based on results from a phase 2 basket trial (NCT02454972) showing overall response rate of 35.2% and duration of response of 5.3 months. The ATLANTIS trial (NCT02566993) assessed the combination of lurbinectedin 2mg/m²/ doxorubicin (DOX) 40 mg/m² as second-line treatment for SCLC vs. a control arm of topotecan/CAV. Methods: This post hoc analysis explores the efficacy and safety of lurbinectedin in relapsed SCLC patients ≥65 years included in both phase 2 basket (26 patients treated with lurbinectedin) and ATLANTIS (121 patients treated with lurbinectedin/DOX and 118 patients treated in the control arm) trials. This analysis did not include patients from the phase 2 basket trial with chemotherapy-free interval (CTFI) < 30 days, as these patients were excluded in the ATLANTIS trial. Results: Median age was similar (72.5 in lurbinectedin basket vs. 69 in ATLANTIS lurbinectedin/DOX vs. 69 in ATLANTIS control arm), most were males (65.4% vs. 57.9% vs. 60.2%), with ECOG PS 1 (65.4% vs. 68.6% vs. 68.6%) and CNS involvement (7.7% vs. 10.7% vs. 15.3%). Median CTFI (days) was also similar (105.5 vs. 123 vs. 120). Median number of cycles was 4 vs. 6 vs. 4. Main efficacy and safety results are shown in the table. Treatment-related adverse events (AEs) were reported in 92.3%, 92.6% and 94.1% of patients, respectively (grade ≥3 in 50.0%, 59.5% and 81.4%). Conclusions: In elderly patients, lurbinectedin seems to be superior to the standard of care in terms of both efficacy (higher response rate and longer duration of response and overall survival) and safety (less associated hematological AEs), which reinforces its role as a treatment option in relapsed SCLC patients ≥65 years. Clinical trial information: NCT02454972, NCT02566993.

* Growth colony-stimulating factors were mandatory for both ATLANTIS treatment arms.** Nominal comparisons in ATLANTIS (small number of patients in basket trial)AEs, adverse events; CI, confidence interval; mo, months; OS, overall survival.