TP53 Mutations as a Driver of Metastasis Signaling in Advanced Cancer Patients

SIMPLE SUMMARY: The DNA sequencing of cancer provides information about specific genetic changes that could help with treatment decisions. Tumors from different tissues change over time and acquire new genetic changes particularly with treatment. Our study analyzed the gene changes of 171 advanced cancer patients. We predicted that tumors gain new mutations but that TP53 mutations (guardian of the human genome) are conserved as the tumor progresses from primary to metastatic sites and across tissue types. We analyzed the primary and metastatic site gene changes in 25 tissue types and conducted in-depth analysis of colon and lung cancer sites for substantial changes. TP53 site specific mutations were different across tissue types and suggest different molecular changes. Other genetic changes that occur together with TP53 as drivers collectively alter how cells respond to signals which are important to tumor treatments. ABSTRACT: Molecular profiling with next generation sequencing (NGS) delivers key information on mutant gene sequences, copy number alterations, gene-fusions, and with immunohistochemistry (IHC), is a valuable tool in clinical decision making for patients entering investigational agent trials. Our objective was to elucidate mutational profiles from primary versus metastatic sites from advanced cancer patients to guide rational therapy. All phase I patients (n = 203) with advanced cancer were profiled by commercially available NGS platforms. The samples were annotated by histology, primary and metastatic site, biopsy site, gene mutations, mutation count/gene, and mutant TP53. A molecular profile of each patient was categorized into common and unique mutations, signaling pathways for each profile and TP53 mutations mapped to 3D-structure of p53 bound to DNA and pre/post therapy molecular response. Of the 171 patients analyzed, 145 had genetic alterations from primary and metastatic sites. The predominant histology was adenocarcinoma followed by squamous cell carcinoma, carcinoma of unknown primary site (CUPS), and melanoma. Of 790 unique mutations, TP53 is the most common followed by APC, KRAS, PIK3CA, ATM, PTEN, NOTCH1, BRCA2, BRAF, KMT2D, LRP1B, and CDKN2A. TP53 was found in most metastatic sites and appears to be a key driver of acquired drug resistance. We highlight examples of acquired mutational profiles pre-/post- targeted therapy in multiple tumor types with a menu of potential targeted agents. Conclusion: The mutational profiling of primary and metastatic lesions in cancer patients provides an opportunity to identify TP53 driver ‘pathways’ that may predict for drug sensitivity/resistance and guide rational drug combinations in clinical trials.