MSK-IMPACT is a clinical sequencing platform able to detect genomic mutations, copy number alterations and structural variants in a panel of cancer-related genes. This assay is implemented prospectively to inform patient enrollment in genomically matched clinical trials at Memorial Sloan Kettering Cancer Center (MSKCC). Sequencing results of tumor and matched normal tissue from a cohort of >10,000 patients with detailed clinical annotation provide an overview of the genomic landscape of advanced solid cancers and bring new insights into molecularly guided cancer therapy. Tumor molecular profiling is a fundamental component of precision oncology, enabling the identification of genomic alterations in genes and pathways that can be targeted therapeutically. The existence of recurrent targetable alterations across distinct histologically defined tumor types, coupled with an expanding portfolio of molecularly targeted therapies, demands flexible and comprehensive approaches to profile clinically relevant genes across the full spectrum of cancers. We established a large-scale, prospective clinical sequencing initiative using a comprehensive assay, MSK-IMPACT, through which we have compiled tumor and matched normal sequence data from a unique cohort of more than 10,000 patients with advanced cancer and available pathological and clinical annotations. Using these data, we identified clinically relevant somatic mutations, novel noncoding alterations, and mutational signatures that were shared by common and rare tumor types. Patients were enrolled on genomically matched clinical trials at a rate of 11%. To enable discovery of novel biomarkers and deeper investigation into rare alterations and tumor types, all results are publicly accessible.

BACKGROUND. Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) are rare and frequently lethal tumors that so far have not been subjected to comprehensive genetic characterization. METHODS. We performed next-generation sequencing of 341 cancer genes from 117 patient-derived PDTCs and ATCs and analyzed the transcriptome of a representative subset of 37 tumors. Results were analyzed in the context of The Cancer Genome Atlas study (TCGA study) of papillary thyroid cancers (PTC). RESULTS. Compared to PDTCs, ATCs had a greater mutation burden, including a higher frequency of mutations in TP53, TERT promoter, PI3K/AKT/mTOR pathway effectors, SWI/SNF subunits, and histone methyltransferases. BRAF and RAS were the predominant drivers and dictated distinct tropism for nodal versus distant metastases in PDTC. RAS and BRAF sharply distinguished between PDTCs defined by the Turin (PDTC-Turin) versus MSKCC (PDTC-MSK) criteria, respectively. Mutations of EIF1AX, a component of the translational preinitiation complex, were markedly enriched in PDTCs and ATCs and had a striking pattern of co-occurrence with RAS mutations. While TERT promoter mutations were rare and subclonal in PTCs, they were clonal and highly prevalent in advanced cancers. Application of the TCGA-derived BRAF-RAS score (a measure of MAPK transcriptional output) revealed a preserved relationship with BRAF/RAS mutation in PDTCs, whereas ATCs were BRAF-like irrespective of driver mutation. CONCLUSIONS. These data support a model of tumorigenesis whereby PDTCs and ATCs arise from well-differentiated tumors through the accumulation of key additional genetic abnormalities, many of which have prognostic and possible therapeutic relevance. The widespread genomic disruptions in ATC compared with PDTC underscore their greater virulence and higher mortality. FUNDING. This work was supported in part by NIH grants CA50706, CA72597, P50-CA72012, P30-CA008748, and 5T32-CA160001; the Lefkovsky Family Foundation; the Society of Memorial Sloan Kettering; the Byrne fund; and Cycle for Survival.

A study of genome evolution in a metastatic breast cancer bearing an activating PIK3CA mutation, following treatment with the PI(3)Kα inhibitor BYL719, shows that all metastatic lesions, when compared to the pre-treatment tumour, had lost a copy of PTEN; parallel genetic evolution of separate sites with different PTEN genomic alterations had led to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition. The emergence and expansion of resistant clonal subpopulations is a major challenge facing the field of targeted therapeutics. Here, the authors study genome evolution in a metastatic breast cancer bearing an activating PIK3CA mutation, following treatment with the phosphatidylinositol-4,5-bisphosphate 3-kinase alpha subunit (PI(3)Kα) selective-inhibitor BYL719. Fourteen metastatic sites were sequenced to reveal that all metastatic lesions, when compared to the pre-treatment tumour, had lost a copy of the gene for the tumour suppressor phosphatase PTEN. Resistance to BYL719 was associated with additional and different PTEN genetic alterations, resulting in loss of PTEN expression. Based on these observations and additional functional characterization, the authors conclude that parallel genetic evolution of separate sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition. Broad and deep tumour genome sequencing has shed new light on tumour heterogeneity and provided important insights into the evolution of metastases arising from different clones1,2. There is an additional layer of complexity, in that tumour evolution may be influenced by selective pressure provided by therapy, in a similar fashion to that occurring in infectious diseases. Here we studied tumour genomic evolution in a patient (index patient) with metastatic breast cancer bearing an activating PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, PI(3)Kα) mutation. The patient was treated with the PI(3)Kα inhibitor BYL719, which achieved a lasting clinical response, but the patient eventually became resistant to this drug (emergence of lung metastases) and died shortly thereafter. A rapid autopsy was performed and material from a total of 14 metastatic sites was collected and sequenced. All metastatic lesions, when compared to the pre-treatment tumour, had a copy loss of PTEN (phosphatase and tensin homolog) and those lesions that became refractory to BYL719 had additional and different PTEN genetic alterations, resulting in the loss of PTEN expression. To put these results in context, we examined six other patients also treated with BYL719. Acquired bi-allelic loss of PTEN was found in one of these patients, whereas in two others PIK3CA mutations present in the primary tumour were no longer detected at the time of progression. To characterize our findings functionally, we examined the effects of PTEN knockdown in several preclinical models (both in cell lines intrinsically sensitive to BYL719 and in PTEN-null xenografts derived from our index patient), which we found resulted in resistance to BYL719, whereas simultaneous PI(3)K p110β blockade reverted this resistance phenotype. We conclude that parallel genetic evolution of separate metastatic sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition.

In addition to guiding therapy, simultaneous DNA sequence analysis of tumor-normal pairs (“tumor-normal sequencing”) reveals inherited cancer predisposition mutations in 3% to 12.6% of pediatric and adult patients with cancer.^1-7 It remains unknown, however, how many inherited mutations would be detected by multigene tumor-normal analysis compared with a traditional family history–based approach to genetic counseling and testing, and what the clinical implications of these findings would be. Selection for genetic testing is traditionally based on pathologic features of the tumor, age at diagnosis, family history of cancer, and other factors represented in clinical practice guidelines.^8-10 Studies have not determined whether inherited mutations found by tumor-normal sequencing would have been detected by traditional approaches to selection for genetic testing.^1-5