Oops, you're using an old version of your browser so some of the features on this page may not be displaying properly.

MINIMAL Requirements: Google Chrome 24+Mozilla Firefox 20+Internet Explorer 11Opera 15–18Apple Safari 7SeaMonkey 2.15-2.23

IMpower133: Gene expression analysis in long-term survivors with ES-SCLC treated with first-line carboplatin and etoposide ± atezolizumab

ESMO Virtual Plenary

Session date: 17-18 June 2021


VP5-2021: IMpower133: Gene expression (GE) analysis in long-term survivors (LTS) with ES-SCLC treated with first-line carboplatin and etoposide (CE) ± atezolizumab (atezo)

Authors: S.V. Liu, T.S.K. Mok, A.S. Mansfield, L. Adler, D. Shames, M. Reck, Show all authors

Published:June 17, 2021DOI:https://doi.org/10.1016/j.annonc.2021.05.799

Download the abstract


Exploratory analyses to characterise LTS (patients [pts] who survived ≥18 mo post randomisation) in IMpower133 showed that more LTS were treated with atezo (anti–PD-L1) + CE than placebo (PBO) + CE (Liu et al. ESMO 2020). Here, we report the association of differential GE (single genes, T-effector [Teff] and B-cell signatures) and published SCLC subtypes (Gay et al. Cancer Cell 2021) in IMpower133 LTS.


Treatment-naive pts with ES-SCLC were randomised 1:1 to four 21-day cycles of C (AUC 5 mg/mL/min IV, day 1) + E (100 mg/m2 IV, days 1-3) combined with atezo (1200 mg IV, day 1) or PBO, followed by maintenance atezo or PBO until disease progression or toxicity. Co-primary endpoints were PFS and OS. Differential GE was analysed using RNA-sequencing (RNA-seq) data in LTS and non-LTS. OS was assessed by Teff and B-cell gene signature expression in both arms. Distribution of recently identified neuroendocrine, non-neuroendocrine and immune-infiltrated subtypes were also assessed in LTS and non-LTS.


271 pts were in the RNA-seq biomarker-evaluable population, 253 of whom had sufficient follow-up for LTS classification (LTS RNA-seq BEP; LTS, n=64; non-LTS, n=189). Within the LTS RNA-seq BEP, significantly more LTS were in the atezo (n=39, 32%) vs PBO arm (n=25, 19%; P=0.027). In both arms within the LTS RNA-seq BEP, distributions of Teff- and B-cell−related genes and gene signatures (≥ median vs < median) were similar in LTS. Exploratory OS efficacy analyses in the LTS RNA-seq BEP suggest that benefit was observed in favour of atezo vs PBO across all Teff and B-cell expression subgroups (high [≥ median]: Teff, HR, 0.65 [95% CI, 0.43, 0.97]; B-cell, HR, 0.75 [95% CI, 0.51, 1.11], and low [< median]: Teff, HR, 0.75 [95% CI. 0.52, 1.11]; B-cell, HR, 0.66 [95% CI: 0.45, 0.97]). Among the LTS RNA-seq BEP in both arms, GE subtype distribution was broadly similar for LTS.


In IMpower133, more LTS were treated with atezo + CE vs PBO + CE. Enhanced immune-related signaling was seen in LTS in both arms. Atezo and PBO had similar GE-defined subtype distribution, suggesting that subtype associations with outcome may be prognostic.

This site uses cookies. Some of these cookies are essential, while others help us improve your experience by providing insights into how the site is being used.

For more detailed information on the cookies we use, please check our Privacy Policy.

Customise settings
  • Necessary cookies enable core functionality. The website cannot function properly without these cookies, and you can only disable them by changing your browser preferences.