WCLC 2025 - Posters & ePosters-P1.11.18 Real-World Characterization of Response Kinetics in Patients With Metastatic NSCLC Receiving First-Line Immunotherapy

P1.11.18 Real-World Characterization of Response Kinetics in Patients With Metastatic NSCLC Receiving First-Line Immunotherapy

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This retrospective study analyzed tumor response kinetics and survival outcomes in 414 metastatic non-small cell lung cancer (mNSCLC) patients treated with first-line (1L) anti-PD-(L)1 immunotherapy across 10 US and European centers. Response was assessed via RECIST v1.1 on routine CT scans, focusing on change in the sum of longest diameters (SLD) at approximately 3 months post-treatment initiation, defined as depth of response (DepOR). Patients had a median age of 69 years and mostly presented adenocarcinoma histology; about half had high PD-L1 expression and received anti-PD-(L)1 combined with chemotherapy.<br /><br />The study found that early tumor shrinkage at 3 months is strongly associated with longer real-world progression-free survival (rwPFS) and overall survival (OS). Specifically, SLD reductions (SLD-R) of 36.5% and 34.8% optimally predicted improved rwPFS and OS, consistent with the standard 30% RECIST threshold for response. Patients were stratified by SLD-R subgroups: those with 50-100% shrinkage had significantly better rwPFS and a trend toward improved OS compared to those with modest (0-50%) reduction; patients showing no shrinkage or progression had the poorest outcomes. Deepening of response beyond 3 months was rare (~8%), indicating early response is predictive of eventual maximal benefit.<br /><br />Approximately 28% of patients had tumor growth or progressive disease at 3 months, while 55% had up to 50% tumor reduction. Patients treated with anti-PD-(L)1 monotherapy or chemo-immunotherapy had similar response distributions. The results suggest that 3-month tumor response assessment can identify patients unlikely to achieve substantial further shrinkage, thus informing early treatment intensification strategies to improve outcomes.<br /><br />In conclusion, measuring DepOR at 3 months post-1L anti-PD-(L)1 therapy effectively predicts survival in mNSCLC and may guide personalized treatment escalation. This real-world evidence supports existing RECIST response criteria for immunotherapy and highlights the clinical value of early radiologic evaluation in optimizing patient management.

Asset Subtitle

Melina Marmarelis

Meta Tag

Speaker Melina Marmarelis

Topic Metastatic Non-small Cell Lung Cancer – Immunotherapy

Keywords

metastatic non-small cell lung cancer

mNSCLC

anti-PD-(L)1 immunotherapy

depth of response

tumor shrinkage

RECIST v1.1

progression-free survival

overall survival

early tumor response

chemo-immunotherapy