LBA89 - PD-L1 expression, patterns of progression and patient-reported outcomes (PROs) with durvalumab plus platinum-etoposide in ES-SCLC: Results from CASPIAN

In the phase III CASPIAN trial, durvalumab (D) in combination with etoposide plus either cisplatin or carboplatin (EP) significantly improved the primary endpoint of OS vs EP alone in pts with extensive-stage small-cell lung cancer (ES-SCLC). Here we describe clinically relevant analyses for D + EP vs EP based on PD-L1 expression, progression patterns and PROs. Tx-naive ES-SCLC (WHO PS 0/1) pts received 4 cycles of EP plus D q3w followed by maintenance D q4w or up to 6 cycles of EP q3w + prophylactic cranial irradiation (PCI; investigator’s discretion). PD-L1 expression in optional archival tissue was tested by VENTANA PD-L1 (SP263) immunohistochemistry assay. PROs were assessed using EORTC QLQ-C30/LC13 with changes from baseline analysed by time to deterioration (TTD) per Cox proportional hazards. As of 11 March 2019, 265 and 266 pts had received D + EP and EP, respectively. Of 277 with evaluable samples (D + EP, 151; EP, 126), PD-L1 expression was low (5% and 22% of pts with expression ≥1% in tumour (TC) and immune cells (IC), respectively). Evaluating PD-L1 expression as a continuous variable in either TC or IC indicated no significant impact of PD-L1 on Tx effect between arms for OS (P=0.54 and 0.23, respectively); nor for PFS and ORR. Progression patterns were similar, although fewer pts developed new lesions at first progression with D + EP vs EP (41.4% vs 47.2%), including lung lesions (8.6% vs 15.2%). The incidence of new brain/CNS metastases was similar between arms (11.6% vs 11.5%), despite PCI allowance in the control arm only. Baseline PRO scores were comparable across all symptoms and functional domains. TTD was longer across all PROs for D + EP (favourable HRs, many with upper 95% CIs