Real-World Data From the IMreal Trial (Cohort 4) of First-Line Atezolizumab Plus Carboplatin/Etoposide in Patients With Extensive-Stage SCLC

Atezolizumab plus carboplatin/etoposide is indicated for the first-line treatment of extensive-stage small cell lung cancer (ES-SCLC) based on results of the pivotal phase 3 IMpower133 trial. The noninterventional, multicenter, multicohort, prospective IMreal (NCT03782207) study evaluated the clinical outcomes and safety of atezolizumab plus carboplatin/etoposide in the real-world setting; the third interim analysis of efficacy and safety data from cohort 4 of the study in patients with ES-SCLC are summarized here.

Cohort 4 of the IMreal trial enrolled adult patients with a confirmed diagnosis of ES-SCLC who were previously untreated. Eligible patients received first-line atezolizumab + carboplatin/etoposide. The primary end points were overall survival (OS) and 2-year OS; secondary end points included progression-free survival (PFS), overall response rate (ORR), disease control rate, and duration of response (DOR). Date of data cutoff was June 1, 2022.

A total of 676 patients were enrolled in the study between December 2, 2019, and June 1, 2022. The full analysis study (FAS) population included 501 patients in the current analysis. The median age of the study population was 66 years; the majority (58.5%) of patients were ≥65 years, male (65%), and had Eastern Cooperative Oncology Group performance status ≤1. Median time on study for the FAS population was 6.1 months.

In the 501 patients evaluable for efficacy in the FAS population, an ORR of 68% was achieved, including 3% (n=11) complete responses and 65% (n=255) partial responses; DOR was 5.4 months. Median OS was 9.9 months and median PFS was 6.2 months; 1-year OS rate was 39% and 1-year PFS rate was 16%. Median duration of clinical benefit was 7.3 months.

Of the 496 patients evaluable for safety, 83% experienced ≥1 adverse event (AE). The most common AEs (any grade, ≥5%) included anemia (20%), fatigue (17%), neutropenia (16.5%), and nausea (15%). Grade 3/4 treatment-related AEs (TRAEs) were reported in 29% of patients; the most common all-cause grade ≥3 AEs were neutropenia (13%), anemia (9%), pneumonia (4%), and thrombocytopenia (4%). There were 7 TRAE deaths, and serious AEs occurred in 39% of patients. AEs of special interest (AESIs) were reported in 22% of patients; the most common AESIs (any grade) included hepatitis (diagnosis and lab abnormalities; 7%), immune-mediated rash (6%), and hepatitis (lab abnormalities; 6%).

Based on the current interim analysis of the IMreal trial (cohort 4), the authors concluded that the real-world data with first-line atezolizumab + carboplatin/etoposide therapy were slightly different from those previously reported in the pivotal phase 3 IMpower133 trial in patients with ES-SCLC (median OS was slightly shorter and median PFS was slightly longer); however, the safety profile was consistent with no safety risks identified.


Popat S. IMreal cohort 4: third interim analysis of efficacy and safety in patients (pts) with extensive-stage small cell lung cancer (ES-SCLC) receiving atezolizumab plus carboplatin and etoposide (atezo + CE) as first-line (1L) therapy under real-world conditions (RWCs). Abstract presented at: ESMO Annual Meeting, October 20-24, 2023; Madrid, Spain. Abstract 1999P.

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