(B) Tumor from index patient with mutations and an additional mutation in (W606*). 15 patients) in the negative regulatory region and Pro-Glu-Ser-ThrCrich domains, the same two hotspots seen in T-cell acute lymphoblastic leukemias, and led to pathway activation in vitro. = .004). mutations define a distinct aggressive ACC subgroup with a significantly higher likelihood of solid subtype ( .001), advanced-stage disease at diagnosis (= .02), higher rate of liver and bone metastasis ( .02), shorter relapse-free survival (median, 13 34 months; 122 months; = .001) when compared with activating mutation. Furthermore, an index patient with mutations define a distinct disease phenotype characterized by solid histology, liver and bone metastasis, poor prognosis, and potential responsiveness to Notch1 inhibitors. Clinical studies targeting Notch1 in a genotype-defined ACC subgroup are warranted. INTRODUCTION Duocarmycin SA Adenoid cystic carcinoma (ACC) is a common malignant salivary gland tumor with a recurrence rate Duocarmycin SA of 40% to 50% after curative intent treatment.1,2 Overall, ACC is chemotherapy refractory, and there is no standard of care treatment for patients with recurrent and/or metastatic disease.3 Whole exome sequencing (WES) of ACC samples has shed light on the genetic landscape of this disease and provides evidence for Notch pathway alterations in 11% to 29% of patients.4-6 The Notch pathway is involved in cancer-relevant functions, including maintenance of stem cells, cell fate specification, proliferation, and angiogenesis.7 There are four genes that encode transmembrane receptors (mutations.11,12 Notch1 can act Mouse monoclonal to Neuropilin and tolloid-like protein 1 as a tumor suppressor in other malignancies such as oral squamous cell carcinoma in which loss-of-function mutations occur in the epidermal growth factorClike domain.13-15 In this article, we describe that mutations in ACC occur predominately in the T-ALL hotspots, are activating, and define a subgroup of patients with solid subtype, advanced-stage disease, distinct pattern of metastasis, and worse prognosis. We also report in an index patient that the acquisition of mutations leading to further Notch1 pathway activation probably occurs as the tumor progresses. Furthermore, Notch1 inhibitor demonstrated antitumor activity in a mutation, demonstrating that Notch1 is a potential therapeutic target in a subgroup of ACC. METHODS Patient Selection The study population consisted of 102 patients with ACC: 70 patients with primary tumor available for WES (46 patients in addition to the 24 previously published4) and 32 patients who had their tumor genotyped by using target-sequencing platforms from January 1, 2013, to March 31, 2015, at the request of the treating oncologist. Patient samples were obtained by either an institutional review boardCapproved waiver of informed consent (for deceased patients) or informed consent (front-door consent). Pathologic and clinical data were retrospectively obtained from electronic medical records according to institutional review boardCapproved protocol PA14-0375. Data acquisition was locked on December 7, 2015. At the date of analysis, 46 patients were alive (33 with disease and 13 without disease), and 56 were deceased (44 as a result of disease, five without disease, and seven with unknown disease status). Genomic Analysis WES was performed by using DNA obtained from fresh-frozen samples, as previously described.4 Target exome sequencing or analysis of hotspot mutations in cancer-related genes was performed by using next-generation sequencing as described in the Data Supplement. Immunohistochemistry Rabbit monoclonal cleaved Notch1 antibody Val1744 (D3B8; #4147; Cell Signaling Technology, Danvers, MA) was used for NICD immunohistochemical (IHC) staining as previously described.16 Details are available in the Data Supplement. Luciferase Reporter Assay Luciferase reporter assay was performed by using 293T cells. mutation or NICD expression and clinicopathologic characteristics. An analysis evaluating the association between mutational status and specific sites of disease Duocarmycin SA recurrence was undertaken among patients with local or distant recurrence. Relapse-free survival (RFS) and overall survival (OS) were estimated by the Kaplan-Meier method. RFS was defined as the time from diagnosis to relapse or death, whichever occurred first. Observation for RFS was censored at the date of last contact for patients last known to be alive without relapse. OS was defined as the time from diagnosis to death as a result of any cause. Survivors or patients who were lost to follow-up were censored at the last contact date. Univariable and multivariable analyses that used Cox proportional hazards models were used to identify important prognostic factors for OS and RFS. All values were two-sided. .05 was considered statistically significant. RESULTS Mutations in ACC Occur in Hotspots and Are Associated With Pathway Activation Expanding on our prior work of genetic sequencing for 24 patients with ACC,4 genomic profiling was conducted in a total of 102 tumors, WES in Duocarmycin SA an additional 46 samples, and targeted sequencing for gene panel that included in 32 samples. Eighteen mutations Duocarmycin SA were identified in 15 tumors, and two patients harbored more than one mutation. Seventeen of these mutations in 14 patients (14 [13.7%].