An immunogenic model of KRAS-mutant lung cancer for study of targeted therapy and immunotherapy combinations

Abstract

Mutations in oncogenes such as KRAS and EGFR cause a high proportion of lung cancers. Drugs targeting these proteins cause tumour regression but ultimately fail to cure these cancers, leading to intense interest in how best to combine them with other treatments, such as immunotherapies. However, preclinical systems for studying the interaction of lung tumours with the host immune system are inadequate, in part due to the low tumour mutational burden in genetically engineered mouse models. Here we set out to develop mouse models of mutant Kras-driven lung cancer with an elevated tumour mutational burden by expressing the human DNA cytosine deaminase, APOBEC3B, to mimic the mutational signature seen in human lung cancer. This causes an increase in mutational burden in Kras mutant and p53 deleted (KP) tumours and in carcinogen-induced tumours, but these mutations are sub-clonal and do not lead to sensitivity of the autochthonous tumours to immune interventions. However, when clonal cell lines are derived from these tumours they provide an immunogenic syngeneic transplantation lung cancer model that is sensitive to immunotherapy. The ability of a KRAS-G12C inhibitor to cause regression of these tumours is markedly potentiated by the adaptive immune system, providing an opportunity for the study of combinations of targeted and immunotherapies in immune-hot lung cancer.

Targeted cancer therapy induces APOBEC fuelling the evolution of drug resistance

“…In this study, the impact of A3B on epidermal growth factor receptor (EGFR)-driven lung cancer evolution was assessed. EGFR mutant NSCLC mouse models containing a human A3B transgene 7 were generated, and the effect of enforced A3B expression was evaluated at multiple timepoints. Enforced A3B expression was detrimental to tumour initiation and progression in the absence of targeted therapy due to elevated chromosomal instability (CIN) and p53 activation, which increased significantly in tumours with A3B expression.…”

Therapeutic KRASG12C inhibition drives effective interferon-mediated anti-tumour immunity in immunogenic lung cancers

“…An increased presence of exhausted T cells and augmented IFN responses suggest that MRTX treatment has the potential to sensitize these tumours to ICB. Nevertheless, in this immune-resistant model ( 28 To extend our findings, we made use of the KPB6 G12C cell line, which has been established from the KRAS LSL_G12D/+ ;Trp53 fl/fl mice (KP) and genetically engineered to express a KRAS G12C mutation (25). Due to the low number of clonal somatic SNVs, this model develops immune cold lung tumours (25).…”

“…Nevertheless, in this immune-resistant model ( 28 To extend our findings, we made use of the KPB6 G12C cell line, which has been established from the KRAS LSL_G12D/+ ;Trp53 fl/fl mice (KP) and genetically engineered to express a KRAS G12C mutation (25). Due to the low number of clonal somatic SNVs, this model develops immune cold lung tumours (25). Orthotopic KPB6 G12C lung tumours were highly sensitive to KRAS G12C inhibition (Fig S6E).…”

“…We therefore investigated the effects of KRAS G12C inhibition in a new immunogenic model of KRAS-mutant lung cancer. The KPAR G12C cell line has been shown to be immunogenic as its growth is impaired by the adaptive immune system (25). Treatment of subcutaneous KPAR G12C -tumour bearing mice with a KRAS G12C inhibitor resulted in outstanding tumour control, with two out of seven mice achieving complete responses (Fig 7A were also resistant to tumour re-challenge, suggesting the development of immune memory.…”

“…KRAS G12V -ER pneumocytes were generated as previously described (14). KPAR-KRAS G12C and KPB6-KRAS G12C were generated as previously described (25). CT26-KRAS G12C were obtained from Mirati Therapeutics (Briere).…”