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 significant genes across the full spectrum of cancers. We established a large-scale, prospective clinical sequencing initiative utilizing a comprehensive assay, MSK-IMPACT, through which we have compiled matched tumor and 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 non-coding alterations, and mutational signatures that were shared among 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.

Although the majority of acute myeloid leukemia (AML) patients initially respond to chemotherapy, many patients subsequently relapse; the mechanistic basis for AML persistence following chemotherapy has not been delineated. Recurrent somatic mutations in DNA methyltransferase 3A (DNMT3A), most frequently at arginine 882 (DNMT3Amut), are observed in AML1–3 and in individuals with clonal hematopoiesis in the absence of leukemic transformation4,5. DNMT3Amut AML patients have an inferior outcome when treated with standard-dose daunorubicin-based induction chemotherapy6,7, suggesting that DNMT3Amut cells persist and drive relapse8. Here we show that Dnmt3amut induces hematopoietic stem cell (HSC) expansion, cooperates with Flt3ITD and Npm1c to induce AML in vivo, and promotes resistance to anthracycline chemotherapy. In AML patients, DNMT3AR882 mutations predict for minimal residual disease (MRD), underscoring their role in AML chemoresistance. DNMT3Amut cells show impaired nucleosome eviction and chromatin remodeling in response to anthracyclines, resulting from attenuated recruitment of histone chaperone SPT-16 following anthracycline exposure. This defect leads to an inability to sense and repair DNA torsional stress, which results in increased mutagenesis. Our studies identify a critical role for DNMT3AR882 mutations in driving AML chemoresistance, and highlight the importance of chromatin remodeling in response to cytotoxic chemotherapy.

Clear cell carcinoma of the endometrium is a rare type of endometrial cancer generally associated with an aggressive clinical behavior. Here we sought to define the repertoire of somatic genetic alterations in endometrial clear cell carcinomas (ECCs) and whether ECCs could be classified into the molecular subtypes described for endometrial endometrioid and serous carcinomas. We performed a rigorous histopathological review, immunohistochemical analysis and massively parallel sequencing targeting 300 cancer-related genes of 32 pure ECCs. Eleven (34%), seven (22%) and six (19%) ECCs displayed abnormal expression patterns of p53, ARID1A and at least one DNA mismatch repair protein, respectively. Targeted sequencing data were obtained from 30 of the 32 ECCs included in this study, which revealed that two ECCs (7%) were ultramutated and harbored mutations affecting the exonuclease domain of POLE. In POLE wild-type ECCs, TP53 (46%), PIK3CA (36%), PPP2R1A (36%), FBXW7 (25%), ARID1A (21%), PIK3R1 (18%) and SPOP (18%) were the genes most commonly affected by mutations, and 18% and 11% harbored CCNE1 and ERBB2 amplifications, respectively, while 11% showed DAXX homozygous deletions. In comparison to non-POLE endometrioid carcinomas from The Cancer Genome Atlas (TCGA), ECCs less frequently harbored mutations affecting CTNNB1 and PTEN but more frequently PPP2R1A and TP53 mutations. Compared to endometrial serous carcinomas (TCGA), ECCs less frequently harbored TP53 mutations. Using a surrogate model for the molecular-based TCGA classification, all molecular subtypes previously identified in endometrial endometrioid and serous carcinomas were present in the ECCs studied, including POLE, MMR-deficient, copy-number high (serous-like)/p53 abnormal and copy-number low (endometrioid)/p53 wild-type, which were significantly associated with disease-free survival in univariate analysis. These findings demonstrate that ECCs are a histologically and genetically heterogeneous group of tumors with varying outcomes. Furthermore, our data suggest that the classification of ECCs as being generally “high-grade” or “type II” tumors may not be warranted.

Minimal residual disease (MRD) in acute myeloid leukemia (AML) is typically measured using multiparameter flow cytometry (MFC). Detection of leukemia mutations using multigene next-generation sequencing (NGS) can potentially be used to measure residual disease. We used a targeted 28-gene NGS panel to detect mutations and different-from-normal 10-color MFC to measure MRD in AML patients before allogeneic hematopoietic stem cell transplantation (HCT). Residual disease was defined when any abnormal blast population was detected using MFC and when any leukemia allele was detected with a variant allele frequency (VAF)  ≥ 5% using NGS. We tracked the clearance of leukemia alleles between AML diagnosis and immediately before HCT and found that mutations in DNMT3A, TET2, and JAK2 were less likely to be cleared than NPM1, IDH 1/2, and FLT3-ITD. Despite varying sensitivities, the concordance rate of residual disease detection before HCT using the 2 assays was 44 of 62 (71%) evaluable cases. Discordance could be explained by residual mutations in DNMT3A and TET2 that were not detected by MFC and presence of residual leukemia mutations with VAF below the established thresholds for mutation calling. Presence of flow MRD and residual mutations immediately before HCT using the 2 assays was associated with relapse risk (MFC: hazard ratio,  4.62; 95% confidence interval [CI], 1.32 to 16.09; P = .016 and NGS: hazard ratio,  4.35; 95% CI, 1.63 to 11.6; P = .003) and survival (MFC: hazard ratio,  2.44; 95% CI, 1 to 5.97; P = .05 and NGS: hazard ratio, 2.1; 95% CI, .97 to 4.55; P = .059) after HCT. Residual disease detected concurrently by MFC and NGS conferred the highest relapse risk compared with patients who were either negative by both assays or had discordant status (overall, P = .008). Although MFC is universally applicable, a multigene NGS approach to measuring residual disease in AML provides additional information on differential clearance of disease alleles and can assess clonal architecture before transplantation.

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