201P Efficacy of carboplatin-etoposide rechallenge after first-line chemo-immunotherapy in ES-SCLC: An international multicentric analysis

Extensive Stage Small cell Lung Cancer (ES-SCLC) is an aggressive disease with poor outcomes. Although most patients (pts) initially respond to first-line (1L) treatment, eventually all will relapse. Second-line (2L) therapeutic options have limited efficacy. For pts with platinum-free interval (PFI) ≥90 days, rechallenge with carboplatin-etoposide (CE) is a standard option. A phase 3, randomized trial comparing rechallenge CE vs topotecan in pts with PFI ≥90 days, demonstrated longer progression-free survival (PFS) in the rechallenge group (4.7 m vs 2.7 m; HR=0.57; p=.0041) but similar (7.5 v 7.4 m) overall survival (OS). However, this study pre-dates the use of 1st line chemo-immunotherapy (CT-IO) therefore the efficacy of platinum rechallenge after CT-IO is still unclear. Real-world data could offer valuable insights for this strategy. We retrospectively reviewed pts with ES-SCLC who received second-line rechallenge CE after first-line CT-IO between September 2020 and August 2023 in 9 European centres. Demographic and clinical data were collected and analysed. A total of 93 pts were included. Sixty-six pts (71%) had PFI between 3 and 6 m. Clinical and demographic characteristics stratified by PFI are shown in the table. Consolidation thoracic radiotherapy and prophylactic cranial irradiation had been administered in 31 pts (33.3%) and 20 pts (21.5%), respectively. ORR was 59.1%. Median PFS was 5 m (95% CI, 4.3 – 5.7) and median OS was 7 m (95% CI, 5.7 – 8.3). Notably, PFS and OS were not different according to PFI (3-6 m v > 6 m). Table: 201PDemographic and clinical characteristicsPFI 3-6 months (N = 66)PFI > 6 months (N = 27)Sex – no. (%)Male31 (47.0)15 (55.6)Female35 (53.0)12 (44.4)Median age – years (range)65 (43 – 84)67 (45 – 81)ECOG – no. (%)03 (4.5)3 (11.1)152 (78.8)20 (74.1)211 (16.7)4 (14.8)Smoking status – no. (%)Never smoker0 (0.0)1 (3.7)Former smoker34 (51.5)10 (37.0)Current smoker32 (48.5)16 (59.3)Liver metastases – no. (%)No39 (59.1)22 (81.5)Yes27 (40.9)5 (18.5)Brain metastases – no. (%)No61 (92.4)22 (81.5)Yes5 (7.6)5 (18.5) Open table in a new tab Rechallenge with CE is a valid 2L option in pts diagnosed with ES-SCLC who progress after 1L CT-IO. Our analysis shows similar results compared to previous studies. Furthermore, outcomes were consistent across pts with different PFIs, confirming its efficacy in pts with PFI > 3 months.