1533P Atezolizumab (ATZ) plus carboplatin (Cb) and etoposide (eto) in patients with untreated extensive-stage small cell lung cancer (ES-SCLC): Results from the interim analysis of MAURIS trial

Abstract

MAURIS is a multicenter, open label, single arm, phase IIIb trial conducted in 25 Italian centers, that evaluates the safety and efficacy of ATZ + Cb-Eto in patients with newly diagnosed ES-SCLC, according to the new standard of care from the pivotal trial IMpower133. Patients (pts) with ECOG PS2, untreated asymptomatic brain metastases (BM) were eligible for this study and consolidative and palliative radiotherapy was also allowed. An interim analysis (IA) has been conducted roughly one year from the end of enrolment with a median follow-up of 10.5 months. Patients enrolled in the study received ATZ 1200 mg + Cb-Eto every 3 weeks for 4–6 cycles in the induction phase, followed by ATZ maintenance every 3 weeks up to disease progression, unacceptable toxicity or clinical deterioration. The primary endpoints were the incidence of serious adverse events (SAE) and immune-mediated AEs (imAE). The secondary endpoints were 1 year survival, overall survival (OS), progression-free survival (PFS) and overall response rate (ORR). 154 patients (95 males, mean age 65.1 years, 6 pts with PS2, 19 pts with BM) were treated. At data cut-off 28 oct 2021, 139 pts (90.3%) discontinued the treatment: 97 pts (63.0%) due to progressive disease, 17 pts (11.0%) due to AE. Safety data related to the induction phase and efficacy data at data cut-off were analysed overall and by the number of induction cycles.Table: 1533PInduction PhaseTotal n=154≤3 cycles n=224 cycles n=43≥5 cycles n=89Safety n (%)SAEs46 (29.9)14 (63.6)15 (34.9)17 (19.1)Treatment related SAE28 (18.2)6 (27.3)12 (27.9)10 (11.2)imAE23 (14.9)4 (18.2)5 (11.6)14 (15.7)Treatment related AE117 (76.0)13 (59.1)35 (81.4)69 (77.5)Treatment AE leading to death7 (4.5)6 (27.3)0 (0.0)1(1.1)Efficacy1 year survival, n (%)65 (41.9)0 (0.0)18 (41.9)47 (52.8)OS (mo), median (95% CI)10.7 (9.9-13.7)2.7 (1.0-7.6)10.4 (8.6-14.2)13.8 (10.7-18.2)PFS (mo), median (95% CI)5.5 (5.3-5.8)1.8 (1.0-3.9)4.5 (4.1-5.5)5.8 (5.5-6.5)ORR, n (%)111 (71.6)5 (21.7)31 (72.1)75 (84.3) Open table in a new tab In this interim analysis, safety data observed in the induction phase seem consistent with IMpower133 results considering a patient population closer to clinical practice both for baseline patient characteristics and co-treatments allowed. In terms of efficacy data, we found that PFS and ORR were also aligned. Survival data in relation to the number of cycles in the induction phase, according to the investigator’s choice, might reflect a biased population and they should be confirmed.