2003P - Consolidative intrathoracic radiotherapy during maintenance first-line immunotherapy in extensive stage small cell lung cancer (ES-SCLC): A retrospective multicenter analysis of safety and efficacy

Background

Despite recent innovations, ES-SCLC has still poor prognosis. First-line chemo-immunotherapy (CT-IT) improved clinical outcomes without increasing toxicities. Conversely, the role of thoracic radiotherapy (TRT) is largely unknown in this setting. The aim of our study was to evaluate clinical outcomes and safety of first-line CT-IT with or without consolidative TRT in ES-SCLC patients.

Methods

One hundred-three patients (pts) treated in five Italian centers from February 2020 to March 2023 were retrospectively evaluated. Median age was 67 years (range 38-84). All pts had ECOG PS 0-1, except 11 with PS=2. At time of treatment, all pts had ES-SCLC. Overall survival (OS) and progression free survival (PFS) were analyzed using the Kaplan Meier method. Univariate and multivariate analysis was performed to investigate patient, tumor or treatment related prognostic factors influencing clinical outcomes. Toxicity was recorded based on CTCAE 4.0 scale.

Results

At a median follow up of 11 months, 103 pts with ES-SCLC were treated using platinum- based CT-IT followed by maintenance IT with atezolizumab. Consolidative TRT was delivered to 33 responding pts and 14 underwent cranioprophylaxis. Median, 1- and 2-year OS was 14.2 months, 52.6%(SE±5,6%) and 31.4%(SE±6,0%), respectively. Median, 12- and 18-months PFS was 7,1 months, 27.5%(SE ±4,8%) and 14.4(SE ±4,8%), respectively. At univariate analysis consolidative TRT, ECOG PS, absence of brain or bone metastases at diagnosis were positive statistically significant prognostic factors for OS. TRT remains significant at multivariate analysis for OS (p < 0,0001). Toxicities >G2 were reported in 23 pts (22.3%) with hematological toxicity as the most common. Only one G5 toxicity was reported (pneumonitis).

Conclusions

CT-IT was confirmed as an effective therapeutic option in ES-SCLC. Consolidative TRT showed interesting results in terms of both OS and PFS being feasible and safe also in a large “real life” setting. Prospective trials with longer follow up are actually needed to further assess the impact of TRT on local disease control and survival.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

A. Bruni: Non-Financial Interests, Personal and Institutional, Local PI: AstraZeneca; Non-Financial Interests, Personal and Institutional, Speaker, Consultant, Advisor: MSD; Non-Financial Interests, Personal and Institutional, Invited Speaker: AIRO. F. Bertolini: Non-Financial Interests, Personal and Institutional, Local PI: MSD; Financial Interests, Personal and Institutional, Speaker, Consultant, Advisor: AstraZeneca, BMS. P. Borghetti: Non-Financial Interests, Personal and Institutional, Local PI: MSD, AstraZeneca, Roche; Non-Financial Interests, Personal and Institutional, Invited Speaker: AIRO. V. Scotti: Financial Interests, Personal and Institutional, Advisory Board: AstraZeneca, MSD; Financial Interests, Personal and Institutional, Speaker, Consultant, Advisor: AstraZeneca, BMS, Lilly, Roche, Takeda. G. Pasello: Financial Interests, Personal, Invited Speaker: Amgen, Lilly, Novartis, MSD; Financial Interests, Personal, Advisory Board: AstraZeneca, Roche, Janssen; Financial Interests, Institutional, Research Grant: Roche; Financial Interests, Institutional, Other, unconditioned support: AstraZeneca; Non-Financial Interests, Principal Investigator: AstraZeneca, Roche, Novartis, Lilly, Janssen, PharmaMar. N. Giaj-Levra: Financial Interests, Personal and Institutional, Advisory Board: AstraZeneca. G. Guaitoli: Financial Interests, Personal and Institutional, Advisory Board: MSD. All other authors have declared no conflicts of interest.