A novel mismatch repair deficient lung adenocarcinoma model for immunotherapy research

Abstract

Immunotherapy has revolutionised cancer treatment, yet responses vary significantly based on tumour characteristics and microenvironment. Here, we developed and analysed subcutaneous and orthotopic immunocompetent mice models of mismatch repair-deficient (dMMR) lung adenocarcinoma (LUAD) by selectively ablating Mlh1. Subcutaneous tumours demonstrated partial sensitivity to anti-PD-1 therapy, whereas orthotopic tumours exhibited robust responses, with substantial reductions in tumour burden. Although both models displayed to some extent a robust immune microenvironment, they differed in immune cell infiltration patterns following anti-PD-1 treatment, underscoring the critical influence of anatomical site and tumour context in shaping immunotherapy outcomes. Furthermore, the use of clonal cell lines with enriched neoantigen frequency in the orthotopic model highlighted the role of clonal heterogeneity in modulating therapeutic efficacy. Together, our findings emphasise the relevance of orthotopic models for preclinical evaluation and suggest that they more accurately reflect clinical responses to immune checkpoint blockade in dMMR LUAD.

We thank Dr A. Celià-Terrassa, and Dr. K. Sutherland for providing reagents; Dr. Yacine Kharraz and CRG/UPF Flow Cytometry Unit with sample preparation and analysis. This work was supported by grants from the Spanish Ministry of Science and Innovation Grant (PID2021-127710OB-I00, PID2021-128721OB-I00, PID2023-151556OB-I00, CNS2024-154742, CNS2023-144819), “La Caixa” foundation (51110009 and HR22-00402), Worldwide Cancer Research (20–0144), ESF+ (ERDF A way of making Europe), European Union NextGenerationEU/PRTR (ESF Investing in your future). A.J. was supported by Ramon y Cajal Research Fellowship (RYC2018-025244-I), I.Z. is funded by an AECC Postdoctoral Fellowship (POSTD234858ZADR). C.L.-R. is supported by the ICREA Acadèmia program of Generalitat de Catalunya. A.K. was supported by a predoctoral fellowship of the Spanish Ministry of Science and Innovation (PRE2019-088166). L.P. was founded by PID2023-151556OB-I00, CNS2024-154742, “ERDF A way of making Europe” and, as appropriate, by “ESF Investing in your future”, by “ESF+” or by “European Union NextGenerationEU/PRTR”. This work was made possible through the “Unidad de Excelencia María de Maeztu'' funded by the MCIN and AEI (CEX2018-000792-M).