Abstract 193P
Background
The Effective Dose to Immune Cells (EDIRC) is a dosimetry-based metric that estimates radiation exposure to circulating immune cells during radiotherapy. Elevated EDIRC is linked to lymphopenia, immune dysfunction, and poor tumor control in unresectable non-small cell lung cancer (NSCLC) after chemoradiation (CRT). However, it is unclear if EDIRC directly correlates with clinical outcomes and particularly with durvalumab consolidation, or if confounding factors drive this association. This study examined whether EDIRC independently correlates with progression free survival (PFS).
Methods
Data from unresectable NSCLC patients treated with CRT and durvalumab between 2017–2023 at three tertiary centers were analyzed. Maximally selected rank statistic determined the optimal EDIRC cutoff, and multivariable analysis evaluated its correlation with PFS.
Results
A total of 239 NSCLC patients were categorized into low and high EDIRC groups. For the entire cohort, the median PFS was 22.4 months. The EDIRC cutoffs was 8.5. Patients in the low EDIRC group demonstrated significantly longer PFS compared to those in the high EDIRC group (27.8 months vs. 10.6 months, HR=0.48, p < 0.0001). Subgroup analysis by PD-L1 status showed this difference remained statistically significant in the PD-L1 positive cohort (HR=0.41, p=0.005) but not in the PD-L1 negative cohort (HR=0.57, p=0.2). In a multivariable analysis accounting for EDIRC, stage, GTV and PDL-1 status, only EDIRC (HR=0.49, p=0.043) and stage (HR=0.5, p=0.04) remained an independent prognostic factor for PFS.
Conclusions
Lower EDIRC level independently correlates with longer PFS after CRT and durvalumab.
Legal entity responsible for the study
Rabin Medical Center.
Funding
Has not received any funding.
Disclosure
S. Appel: Financial Interests, Personal, Invited Speaker: MSD. M.T. Moskovitz: Financial Interests, Institutional, Research Grant, and Honoria: AstraZeneca; Financial Interests, Personal, Other, Consulting fees: Amgen, Bayer; Financial Interests, Personal, Invited Speaker, Also: Consulting fees and participation on safety monitoring or advisory bords: MSD; Financial Interests, Personal, Invited Speaker, Also: Consulting fees,: Takeda; Financial Interests, Personal, Invited Speaker, and support of travel: Roche, Pfizer. D.J. Reinhorn: Financial Interests, Personal, Invited Speaker: MSD, Bristol Myers Squibb, AstraZeneca. All other authors have declared no conflicts of interest.