1536P Synthetic control arm (SCA) analysis of lurbinectedin compared to the standard of care (SoC) among patients with small cell lung cancer (SCLC) previously treated with platinum-based chemotherapy

Abstract

Lurbinectedin recently received approval from Health Canada based on a single-arm Phase II trial (B-005) demonstrating a positive response to lurbinectedin in patients with relapsed SCLC who were previously treated with platinum-based chemotherapy. We assessed the efficacy of lurbinectedin in the trial population compared to the current SoC in a real-world Canadian SCA. Patients diagnosed with SCLC between 2004-2019 in Alberta, Canada were identified using cancer registry data. Relevant eligibility criteria from the lurbinectedin trial were applied to patients who received platinum-based chemotherapy and initiated a subsequent line of systemic therapy. Overall survival (OS) was examined from initiation of post-platinum therapy. KM estimates were generated for the SCA and standardized to the chemotherapy-free interval (CTFI) and stage distribution of the trial. The CTFI-adjusted hazard ratio (HR) comparing lurbinectedin to the SoC was estimated using a Cox proportional hazards model. 577 patients with SCLC were diagnosed and initiated post-platinum therapy, of which 174 (30%) were included in the SCA (Table). In the SCA, the unadjusted median OS was 6.7 months (95% CI: 6.0 - 7.7) and the CTFI and stage-standardized median OS was 6.1 months (5.4 - 7.7) compared to 9.3 months (6.3 - 11.8) in the lurbinectedin trial. The CTFI-adjusted HR comparing lurbinectedin to the SoC was 0.61 (0.45 - 0.82; p = 0.001; unadjusted HR: 0.72, 0.54 - 0.97; p = 0.028). In a quantitative bias analysis, the estimated HR was similar when adjusting for both CTFI and stage (HR: 0.59, 0.44 - 0.79). For patients with CTFI ≥90 days, the HR was 0.49 (0.33 - 0.73; p<0.001).Table: 1536PBaseline characteristics of SCLC patients in the SCA compared to the trialVariableSCATrialASDn174105-Male (%)85 (48.9)63 (60.0)0.22Age at start of Post-Platinum Tx (mean (SD))65.1 (8.8)60.0 (2.3)0.77ECOG 0-1 (vs 2) (%)146 (85.4)97 (92.4)0.22Extensive Stage at Diagnosis (%)100 (57.5)73 (69.5)0.253+ Metastatic Sites at Baseline (%)41 (23.7)79 (75.2)1.20Bulky Disease (%)51 (30.0)34 (32.4)0.05PCI (%)106 (60.9)61 (58.1)0.06CTFI ≥90 Days (%)145 (83.3)60 (57.1)0.60Post-Platinum Regimen (%)Carbo/Cis + Etoposide126 (72.4)--Other18 (10.3)--CAV17 (9.8)--Etoposide13 (7.5)-- Open table in a new tab These findings suggest potential benefit with initiation of lurbinectedin compared to the SoC in the post-platinum SCLC setting.