T cell receptor engineering for the treatment of EGFR-mutant lung cancer
Introduction
A majority of lung cancers are oncogene driven. Among these, mutations in the Epidermal Growth Factor Receptor (EGFR) gene predominate and are associated with poor clinical outcomes. EGFR tyrosine kinase inhibitors (TKIs) such as Osimertinib have been developed to target the highly prevalent L858R (50.7%) and 746_750del (39.3%), but although initially highly effective, most patients develop resistance. Furthermore, novel EGFR resistance mutations develop in resistance to 2nd Generation (T790M, 50%) and 3rd Generation (C797S, 25%) EGFR TKIs, rendering tumors increasingly aggressive. Despite their lack of responsiveness to immune checkpoint blockade, targeting these essential EGFR-derived neoantigens via cellular therapy may present a clear benefit. Here, we assess the immunogenicity of neoantigens derived from prevalent EGFR mutations and explore development of T cell receptor engineering against these targets for the treatment of non-small cell lung cancer.
Methods
HLA-matched healthy donor PBMCs were stimulated using short peptide antigens for 14 days. Antigen-specific T cells were isolated by tetramer sorting and further expanded for functional assessment. T cells were then screened for their ability to kill target cells expressing the full-length antigen of interest by Chromium-51 release. Full length alpha and beta TCR sequences were identified by single cell RNA sequencing for cloning and in vitro functional validation.
Results
Our findings confirm the immunogenicity of several EGFR-derived neoepitopes (L858R, T790M, C797S) on the highly prevalent HLA-A*02:01, HLA-A*03:01, and HLA-A*11:01 alleles, among others. Importantly, each of these epitopes was naturally endogenously processed and presented by target cells and led to antigen-specific T cell killing, confirming the relevance of these targets. TCRs were retrovirally engineered into healthy donor PBMCs and demonstrated a preserved ability to lyse their targets.
Conclusion
Our work highlights the immunogenicity of predominant EGFR mutants when presented on HLA class I and demonstrates the potential of T cell engineering for the treatment of EGFR-mutant non-small cell lung cancer.