Citations

Abstract Purpose: Receptor tyrosine kinases (RTKs) are frequently deregulated in leukemia, yet the biological consequences of this deregulation remain elusive. The mechanisms underlying aberrant methylation, a hallmark of leukemia, are not fully understood. Here we investigated the role of RTKs in methylation abnormalities and characterized the hypomethylating activities of RTK inhibitors. Experimental Design: Whether and how RTKs regulate expression of DNA methyltransferases (DNMTs), tumor suppressor genes (TSGs) as well as global and gene-specific DNA methylation were examined. The pharmacologic activities and mechanisms of actions of RTK inhibitors in vitro, ex vivo, in mice, and in nilotinib-treated leukemia patients were determined. Results: Upregulation of RTKs paralleled DNMT overexpression in leukemia cell lines and patient blasts. Knockdown of RTKs disrupted, whereas enforced expression increased DNMT expression and DNA methylation. Treatment with the RTK inhibitor, nilotinib, resulted in a reduction of Sp1-dependent DNMT1 expression, the diminution of global DNA methylation, and the upregulation of the p15INK4B gene through promoter hypomethylation in AML cell lines and patient blasts. This led to disruption of AML cell clonogenicity and promotion of cellular apoptosis without obvious changes in cell cycle. Importantly, nilotinib administration in mice and human patients with AML impaired expression of DNMTs followed by DNA hypomethylation, TSG re-expression, and leukemia regression. Conclusions: Our findings demonstrate RTKs as novel regulators of DNMT-dependent DNA methylation and define DNA methylation status in AML cells as a pharmacodynamic marker for their response to RTK-based therapy, providing new therapeutic avenues for RTK inhibitors in overcoming epigenetic abnormalities in leukemia. Clin Cancer Res; 23(20); 6254–66. ©2017 AACR.

685 Background: RAS/BRAF mutations constitutively activate the MAPK pathway in colorectal cancer, and may promote resistance to CRT. We propose that trametinib, a MEK1/2 inhibitor, in combination with 5FU CRT for patients with LARC will improve outcome. Methods: Phase I study with standard 3+3 design in patients with Stage II/III rectal cancer with 3 dose levels of trametinib: 0.5, 1, and 2mg daily with 5FU 225mg/m2/day and 50.4 Gy. Trametinib was given over a 5-day lead-in and continued through the course of CRT. Patients undergo surgery 6-10 weeks after the completion of CRT. An expansion cohort at the maximum tolerated dose (MTD) with 12 patients is ongoing. Tumor tissue is collected prior to therapy, at day 4/5 of trametinib, and at surgery. The primary endpoint is to determine the MTD of trametinib with CRT. Results: 15 patients (10 males, 5 females) have been enrolled and 14 patients are evaluable for toxicities to date. Median age is 53 years (range 35-74). Patients have completed enrollment to all dose levels, with 1 dose-limiting toxicity of diarrhea attributed to 5FU CRT. No grade 4/5 toxicities, and toxicities are shown in the table. Generalized skin rash led to trametinib discontinuation after 2 weeks of therapy for 1 patient, and was held 3 days for 2 patients. At the trametinib dose level of 2mg, 3 out of 7 (43%) patients had a pathological complete response and the average neoadjuvant rectal (NAR) score is 8.1. Tumor RAS/BRAF mutation status is determined. Analysis of tumor tissue shows dose-dependent decrease in phosphorylated-ERK1/2 with increasing doses of trametinib. Conclusions: Initial evaluation shows that the combination of trametinib with 5FU CRT is tolerable and effective, and warrants further investigation in LARC. Clinical trial information: NCT01740648. [Table: see text]

Abstract Breast cancer risks conferred by many germline missense variants in the BRCA1 and BRCA2 genes, often referred to as variants of uncertain significance (VUS), have not been established. In this study, associations between 19 BRCA1 and 33 BRCA2 missense substitution variants and breast cancer risk were investigated through a breast cancer case–control study using genotyping data from 38 studies of predominantly European ancestry (41,890 cases and 41,607 controls) and nine studies of Asian ancestry (6,269 cases and 6,624 controls). The BRCA2 c.9104A>C, p.Tyr3035Ser (OR = 2.52; P = 0.04), and BRCA1 c.5096G>A, p.Arg1699Gln (OR = 4.29; P = 0.009) variant were associated with moderately increased risks of breast cancer among Europeans, whereas BRCA2 c.7522G>A, p.Gly2508Ser (OR = 2.68; P = 0.004), and c.8187G>T, p.Lys2729Asn (OR = 1.4; P = 0.004) were associated with moderate and low risks of breast cancer among Asians. Functional characterization of the BRCA2 variants using four quantitative assays showed reduced BRCA2 activity for p.Tyr3035Ser compared with wild-type. Overall, our results show how BRCA2 missense variants that influence protein function can confer clinically relevant, moderately increased risks of breast cancer, with potential implications for risk management guidelines in women with these specific variants. Cancer Res; 77(11); 2789–99. ©2017 AACR.

Abstract Background. We previously reported an alternative ESR1 somatic gain-of-function chromosomal translocation event in a patient presenting with aggressive, endocrine therapy resistant estrogen receptor (ER) positive disease, producing an in-frame fusion gene consisting of N-terminal ESR1 and the C-terminus of the Hippo pathway coactivator YAP1 (ESR1-YAP1). We recently identified another ESR1 fusion through RNA sequencing (RNA-seq) in advanced stage ER+ disease from a chest wall recurrence in a male patient that was refractory to multiple lines of treatment. Two examples of fusions discovered in primary breast cancer samples include ESR1 fused in-frame to C-terminal sequences from NOP2 (ESR1-NOP2), identified in a resistant cohort from a RNA-seq screen focused on 81 primary breast cancers from aromatase inhibitor clinical trials, and a second ESR1 fusion, fused in-frame to the entire coding sequence of POLH (ESR1-POLH), that was identified from RNA-seq analysis of 728 Cancer Genome Atlas breast samples. This current study extends our previous characterization of ESR1-YAP1 by comparing functional and pharmacological properties of these three additional ESR1 gene fusion events of both early stage and advanced breast cancers. Methods. In vitro and in vivo experiments were conducted to test ESR1 fusions to induce therapeutic resistance, and metastasis. The transcriptional and binding properties of each fusion was also examined. Pharmacological inhibition with Palbociclib, a cyclin-dependent kinase 4/6 inhibitor, was utilized to assess drug sensitivity in ESR1 fusion containing breast cancer cells and in a patient derived xenograft (PDX) model expressing ESR1-YAP1 (WHIM18). Results. The YAP1 and PCDH11x fusions conferred estrogen-independent and fulvestrant-resistant growth. Immunohistochemistry revealed significantly higher numbers of ER+ cells in lungs of mice xenografted with T47D cells expressing the YAP1 and PCDH11x fusions compared to YFP control, NOP2 and POLH fusions. Results from ChIP-seq and microarray studies suggest that these two fusions promote proliferation and metastasis through genomic action by binding estrogen response elements (ERE) and subsequent gene activation. We thereby define these fusions as “canonical” fusions compared to “non-canonical” NOP2 and POLH fusions, which demonstrated dramatically decreased genomic binding ability. The non-canonical fusions induced genes associated with basal-like breast cancer and promoted HER2, EGFR, and MAPK gene expression signatures in contrast to genes associated with cell cycle/proliferation induced by canonical fusions. The proliferative ability of canonical fusion-containing ER+ cells was inhibited by Palbociclib in a dose-dependent manner. In vivo WHIM18 tumors in mice fed with Palbociclib-containing chow demonstrated significantly reduced tumor volume, growth rate, and weight compared to tumors in mice on control chow. Conclusions. In-frame ERE activating canonical fusions occur in end-stage drug resistant advanced breast cancer and can be added to ESR1 point mutations as a class of recurrent somatic mutation that may cause acquired resistance. Growth induced by these fusions can be antagonized by Palbociclib and is potentially clinically helpful. Citation Format: Lei JT, Shao J, Zhang J, Iglesia M, Cao J, Chan DW, He X, Kosaka Y, Schmidt C, Matsunuma R, Haricharan S, Crowder R, Hoog J, Phommaly C, Goncalves R, Ramalho S, Lai W-C, Hampton O, Rogers A, Tobias E, Parikh P, Davies S, Ma C, Suman V, Hunt K, Watson M, Hoadley KA, Thompson A, Chen X, Perou CM, Creighton CJ, Maher C, Ellis MJ. Recurrent functionally diverse in-frame ESR1 gene fusions drive endocrine resistance in breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD2-03.

Sarcopenia is associated with increased wait‐list mortality, but a standard definition is lacking. In this retrospective study, we sought to determine the optimal definition of sarcopenia in end‐stage liver disease (ESLD) patients awaiting liver transplantation (LT). Included were 396 patients newly listed for LT in 2012 at 5 North American transplant centers. All computed tomography scans were read by 2 individuals with interobserver correlation of 98%. Using image analysis software, the total cross‐sectional area (cm 2 ) of abdominal skeletal muscle at the third lumbar vertebra was measured. The skeletal muscle index (SMI), which normalizes muscle area to patient height, was then calculated. The primary outcome was wait‐list mortality, defined as death on the waiting list or removal from the waiting list for reasons of clinical deterioration. Sex‐specific potential cutoff values to define sarcopenia were determined with a grid search guided by log‐rank test statistics. Optimal search methods identified potential cutoffs to detect survival differences between groups. The overall median SMI was 47.6 cm 2 /m 2 : 50.0 in men and 42.0 in women. At a median of 8.8 months follow‐up, mortality was 25% in men and 36% in women. Patients who died had lower SMI than those who survived (45.6 versus 48.5 cm 2 /m 2 ; P < 0.001), and SMI was associated with wait‐list mortality (hazard ratio, 0.95; P < 0.001). Optimal search method yielded SMI cutoffs of 50 cm 2 /m 2 for men and 39 cm 2 /m 2 for women; these cutoff values best combined statistical significance with a sufficient number of events to detect survival differences between groups. In conclusion, we recommend that an SMI < 50 cm 2 /m 2 for men and < 39 cm 2 /m 2 for women be used to define sarcopenia in patients with ESLD awaiting LT. Liver Transplantation 23 625–633 2017 AASLD .

166 Background: T-DM1 is an antibody-drug conjugate composed of trastuzumab, a stable linker, and the cytotoxic agent DM1. Few T-DM1 data are available in settings approximating clinical practice. We present safety and efficacy data from T-PAS, an expanded access study of T-DM1 in patients (pts) with previously treated HER2-positive MBC. Methods: T-PAS is a US multicenter study of T-DM1 (3.6 mg/kg q3w) in HER2-positive (IHC 3+ or FISH/CISH+) locally advanced or MBC. Key eligibility criteria: prior anthracycline and taxane; prior capecitabine or 5-FU and ≥2 HER2-directed agents (including trastuzumab and lapatinib) for MBC; LVEF ≥50%. Primary endpoint: safety; secondary endpoint: investigator-assessed objective response rate (ORR) in pts with measurable disease. Safety was assessed on day 1 of each cycle; ECHO/MUGA scans were every 12 weeks. Results: This analysis includes 215 pts enrolled in May 2010–Sep 2011 (data cutoff 7/31/2012). Pts received a median of 7 prior systemic MBC therapies (range 1–23) with a median cumulative anthracycline dose of 240 mg/m2(range 6–2645). At baseline, median LVEF was 60% and 50% of pts had investigator-reported cardiovascular disease. Median follow-up was 5.9 months (range 0.1–25.3); median T-DM1 duration was 5.0 months (range 0–23) with 15.8% receiving >18 cycles. ORR was 25.6% (42/164). Rate of grade ≥3 AEs was 43.7% and of SAEs of any grade was 18.1%. Most common all-grade AEs were fatigue (50.7%), nausea (36.3%), and headache (24.2%). Most common grade ≥3 AEs were thrombocytopenia (7.9%), fatigue (4.7%), and increased aspartate aminotransferase and anemia (each 3.7%). There were no grade ≥3 bleeding events. Cardiac dysfunction (primarily asymptomatic decreases in LVEF) was reported in 8 pts (3.7%); 4 were grade ≥3, 3 resulting in T-DM1 discontinuation. Conclusions: In this study that more closely reflects the real-world setting, the safety profile of T-DM1 was similar to that previously reported in conventional clinical trials, with no new safety signals. In this pretreated population (median of 7 prior therapies for HER2-positive MBC), significant activity was observed. Clinical trial information: NCT01120561.

BackgroundSyncope is a common reason for outpatient transthoracic echocardiography (TTE). We studied the applicability of pediatric appropriate use criteria (AUC) on initial outpatient evaluation of children (≤18 years) with syncope.MethodsData were obtained before (Phase I, April–September 2014) and after (Phase II, January‐April 2015) the release of the AUC document from six participating pediatric cardiology centers. Site investigators determined the indication for TTE and assigned appropriateness rating based on the AUC document: Appropriate (A), May Be Appropriate (M), Rarely Appropriate (R), or “unclassifiable” (U) if it did not fit any scenario in the AUC document.ResultsOf the total 4562 TTEs, 310 (6.8%) were performed for syncope: 174/2655 (6.6%) Phase I and 136/1907 (7.1%) Phase II, P=.44. Overall, 168 (50.5%) were for indications rated A, 63 (18.9%) for M, 79 (23.7%) for R, and 23 (6.9%) for U. Release of AUC did not change the appropriateness of TTEs [A=51.6% vs 49.0%, P=.63, R=20.2% vs 28.3%, P=.09]. Overall syncope‐related R indications formed 15.7% of R indications for all the echocardiograms performed in the entire Pediatric Appropriate Use (PAUSE) study (11.9% Phase I and 22.4% Phase II, P=.002). TTEs were normal in majority of the patients except 7 that had incidental findings.ConclusionsIn conclusion, syncope is a common reason for indications rated R and release of the AUC document did not improve appropriate utilization of TTE in syncope. Targeted educational interventions are needed to reduce unnecessary TTEs in children with syncope.