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Despite the importance of the vasculature during tumorigenesis and during antiangiogenesis treatment, there are few methods available to visualize conveniently the three‐dimensional microvascular structure of tumors. Micro‐computed tomography provides a means to visualize conveniently and quantitatively the three‐dimensional tumor microvascular architecture during tumorigenesis and treatment. In the present study, micro‐computed tomography was utilized to visualize the vasculature of hepatic tumors in SV‐40 transgenic rats. The rats were anesthetized and the vasculature of the livers was infused via an aortic cannula, first with heparinized 0.9% saline, then with 10% buffered formalin and finally with radiopaque silicone rubber (Microfil 122). The livers were first scanned by micro‐CT to visualize the microvasculature and then prepared for histology to visualize the parenchyma. At 10 months of age, all transgenic rats developed gross tumors in their livers. Histological examination revealed that the malignant hepatic lesions in the livers displayed mixed structures resembling hepatoblastoma, cholangiocellular or hepatocellular differentiation in human. Various sized vessels were visible extending to the tumors. Three‐dimensional micro‐computed tomography showed that those vessels were disorganized and tortuous with atypical branching patterns. Often vascular “lakes” were found in the mass of the large tumors. These results show the utility of micro‐computed tomography for studying tumor vasculogenesis. Supported in part by NIH grant EB 000305.

Transforming growth factor beta (TGF‐β) plays a significant role in diverse biologic processes, including the regulation of cell growth, survival, differentiation, development, inflammation, immunity, hematopoiesis, and tissue remodeling. TGF‐β is essential for wound healing, stimulates matrix molecule deposition, and has been implicated in the pathogenesis of a variety of fibrotic disorders, including idiopathic pulmonary fibrosis, scleroderma, radiation‐induced pulmonary fibrosis, and asthma. Furthermore, activation of profibrotic TGF‐β signaling has a central role in glucose‐induced cell hypertrophy, induces glucose transporter 1, and regulates mitochondrial energetics. However, the mechanisms by which TGF‐β induces specific metabolic alterations in the fibrogenic process have not been fully defined. In this study, we demonstrate that TGF‐β stimulates type I TGF β receptor (TβRI) translocation to the mitochondria and induction of hexokinase 2 (HK2) via both Smad‐dependent and –independent pathways. Also, we showed that TbRI association with HK2 and the mitochondrial voltage‐dependent ion channel (VDAC). These findings suggest that TβRI plays a novel role in controlling mitochondrial function and regulation of glucose metabolism. Support or Funding Information This work was supported by Public Health Service grants GM‐055816 and GM‐054200 from the National Institutes of General Medical Sciences. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

INTRODUCTION: Gastroenterologists at all levels of practice benefit from formal mentoring. Much of the current literature on mentoring in gastroenterology is based on expert opinion rather than data. In this study, we aimed to identify gender-related barriers to successful mentoring relationships from the mentor and mentee perspectives. METHODS: A voluntary, web-based survey was distributed to physicians at 20 academic institutions across the United States. Overall, 796 gastroenterology fellows and faculty received the survey link, with 334 physicians responding to the survey (42% response rate), of whom 299 (90%; 129 women and 170 men) completed mentorship questions and were included in analysis. RESULTS: Responses of women and men were compared. Compared with men, more women preferred a mentor of the same gender (38.6% women vs 4.2% men, P < 0.0001) but less often had one (45.5% vs 70.2%, P < 0.0001). Women also reported having more difficulty finding a mentor (44.4% vs 16.0%, P < 0.0001) and more often cited inability to identify a mentor of the same gender as a contributing factor (12.8% vs 0.9%, P = 0.0004). More women mentors felt comfortable advising women mentees about work-life balance (88.3% vs 63.8%, P = 0.0005). Nonetheless, fewer women considered themselves effective mentors (33.3% vs 52.6%, P = 0.03). More women reported feeling pressured to mentor because of their gender (39.5% vs 0.9% of men, P < 0.0001). Despite no gender differences, one-third of respondents reported negative impact of the COVID-19 pandemic on their ability to mentor and be mentored. DISCUSSION: Inequities exist in the experiences of women mentees and mentors in gastroenterology, which may affect career advancement and job satisfaction.

Niclosamide is a salicylanilide derivative used as antihelminthic agent. Recently, Nic has been screened out as an autophagy modulator by us and other groups and was identified to be a structurally distinct mTORC1 signaling inhibitor. In this work, we measured the long‐lived protein degradation activity and found Niclosamide could inhibit the autophagic process. To elucidate the inhibition of Niclosamide on autophagy, we further tested the lysosomal activity using DQ‐BSA assay and measured protease activity such as Cathepsin B and Cathepsin D with fluorescent substrates. The lower degradation of DQ‐BSA and decreased protease activity after Niclosamide treatments indicated the impaired lysosome function. In addition, both LC‐II and P62 proteins accumulated significantly when treated by Niclosamide suggesting the late stage of autophagy was blocked. The increased pH of lysosome and release of Cathepsins from lysosome to cytosol demonstrated that Niclosamide might affect lysosome resulted from lysosomal membrane permeabilization. Collectively, we firstly disclosed Niclosamide not only inhibited mTORC1 activity but also, as other well‐known lysosome inhibitors, strongly blocked autophagy via lysosomal dysfunction. Grant Funding Source : Supported by Guandong Provincial Natural Science Foundation, China (S2013010015876)

Abstract Purpose: Mutations in KRAS/NRAS (RAS) predict lack of anti-EGFR efficacy in metastatic colorectal cancer (mCRC). However, it is unclear if all RAS mutations have similar impact, and atypical mutations beyond those in standard guidelines exist. Experimental Design: We reviewed 7 tissue and 1 cell-free DNA cohorts of 9,485 patients to characterize atypical RAS variants. Using an in vitro cell-based assay (functional annotation for cancer treatment), Ba/F3 transformation, and in vivo xenograft models of transduced isogenic clones, we assessed signaling changes across mutations. Results: KRAS exon 2, extended RAS, and atypical RAS mutations were noted in 37.8%, 9.5%, and 1.2% of patients, respectively. Among atypical variants, KRAS L19F, Q22K, and D33E occurred at prevalence ≥0.1%, whereas no NRAS codon 117/146 and only one NRAS codon 59 mutation was noted. Atypical RAS mutations had worse overall survival than RAS/BRAF wild-type mCRC (HR, 2.90; 95% confidence interval, 1.24–6.80; P = 0.014). We functionally characterized 114 variants with the FACT assay. All KRAS exon 2 and extended RAS mutations appeared activating. Of 57 atypical RAS variants characterized, 18 (31.6%) had signaling below wild-type, 23 (40.4%) had signaling between wild-type and activating control, and 16 (28.1%) were hyperactive beyond the activating control. Ba/F3 transformation (17/18 variants) and xenograft model (7/8 variants) validation was highly concordant with FACT results, and activating atypical variants were those that occurred at highest prevalence in clinical cohorts. Conclusions: We provide best available evidence to guide treatment when atypical RAS variants are identified. KRAS L19F, Q22K, D33E, and T50I are more prevalent than many guideline-included RAS variants and functionally relevant.

Recent studies indicated that activated transcription of serum‐inducible genes in humans requires topoisomerase IIβ (TOP2B)‐mediated DNA strand break (DSB) and DNA damage response (DDR) signaling. However, the mechanisms by which TOP2B is regulated in this process are unknown. Here, we identified a novel role of BRCA1‐BARD1 complex in transcription of these genes by regulating TOP2B binding to the transcription start site (TSS). Our genomic and in vitro biochemical analyses demonstrated that BRCA1‐BARD1 complex and TOP2B colocalize in a large number of genes and physically interact for TOP2B ubiquitination. Upon transcriptional activation, BRCA1 is phosphorylated at S1524 by ataxia telangiectasia‐mutated (ATM) and ataxia telangiectasia and Rad3‐related protein (ATR). Intriguingly, unphosphorylatable BRCA1 (S1524A)‐BARD1 complex ubiquitinates TOP2B, but not WT or S1524D BRCA1. Using the TSS of a representative serum‐inducible gene, EGR1 , we found that ubiquitinated TOP2B binds to the DNA with much more stability than deubiquitinated one does. Together, our findings suggest that BRCA1‐BARD1 complex stabilizes TOP2B association with serum‐inducible genes through its E3 ligase function in transcription. Transcriptional activation induces TOP2B‐mediated DSB and DDR signaling to activate ATM/ATR that phosphorylates BRCA1 S1524. Phosphorylated BRCA1 is ineffective in ubiquitinating TOP2B, which loosens it from the DNA. We propose that this loosening may contribute to either mobility or removal of TOP2B.

8030 Background: CARTITUDE-1 is a single arm study of Ciltacabtagene autoleucel (cilta-cel; JNJ-68284528) anti-BCMA CAR-T cell therapy in US patients (pts) with relapsed multiple myeloma (RRMM) refractory to both IMiD and proteasome inhibitor (PI) or with at least 3 prior lines of therapy and previously exposed to anti-CD38 monoclonal antibody (MoAb). While recently reported efficacy results of cilta-cel were encouraging, it is unknown how they compare with similar pts receiving conventional (non CAR-T) treatment. Methods: We utilized a contemporary US-based dataset of pts with MM refractory to anti-CD38 MoAb (MAMMOTH) to identify pts who would meet eligibility for CARTITUDE-1 and who received conventional therapy. We analyzed the intent-to-treat population (ITT) in CARTITUDE-1, defined as pts who underwent apheresis (N=113) and a modified ITT population (mITT) defined as subset of pts who received cilta-cel at the RP2D (N=97). From the MAMMOTH dataset, we identified a population corresponding to CARTITUDE-1 ITT (N=190) and a mITT population, pts without death or progression within 47 days (median time between apheresis and cilta-cel infusion) from onset of therapy (N=122). We calculated propensity scores (PS) with demographics, N of prior therapies, cytogenetics and refractoriness to MM agents as covariates. An analyst blinded to outcomes performed nearest neighbor 1:1 PS matching. We analyzed overall response rate (ORR), progression-free (PFS) and overall survival (OS) for ITT and mITT in CARTITUDE-1 vs matching MAMMOTH cohorts. Results: Ninety-five ITT (75 received bridging therapy, 82 received cilta-cel) and 69 mITT (54 received bridging) CARTITUDE-1 pts matched MAMMOTH pts (Table). Among the pts in the MAMMOTH ITT cohort 34% received pomalidomide, 24% anti-CD38 MoAb, 19% carfilzomib and 35% cytotoxic chemotherapy in next therapy. ORR in the ITT cohorts was higher in CARTITUDE-1 (84% vs. 28%). Compared to their MAMMOTH counterparts, pts in CARTITUDE-1 ITT cohort had improved PFS (12 mo. 73% vs. 12%) and OS (12 mo. 83% vs 39%). Between the mITT cohorts, CARTITUDE-1 pts had superior ORR (96% vs. 30%), PFS (12 mo 79% vs. 15%) and OS (12 mo. 88% vs. 41%). Conclusions: In pts with RRMM beyond therapy with IMID, PI, and anti-CD38 MoAb, treatment with cilta-cel is associated with higher response rate and superior PFS and OS when compared to conventional treatment.[Table: see text]

TPS3151 Background: Tucatinib (TUC) is a highly selective HER2-directed TKI approved in combination with trastuzumab (Tras) and capecitabine (Cape) for HER2 overexpressed/amplified (HER2+) metastatic breast cancer (BC), based on a statistically significant and clinically meaningful PFS, OS, and ORR benefit over Tras and Cape. In xenograft models of HER2+ and HER2-mutated (HER2-mut) tumors, dual targeting of HER2 with TUC and Tras showed superior activity to either agent alone. While various HER2-directed agents have been evaluated in HER2+ and HER2-mut tumors, there are no approved HER2 therapies outside of breast and gastric cancers. The SGNTUC-019 basket study is evaluating TUC combined with Tras in patients (pts) with HER2+ or HER2-mut locally-advanced unresectable or metastatic solid tumors. Methods: SGNTUC-019 (NCT04579380) is a multi-cohort, open-label, international phase 2 study. Eligible pts must have progressed on or after the last systemic therapy for advanced disease. Metastatic cervical cancer: must have received platinum-based chemotherapy ± bevacizumab; hormone receptor positive (HR+) HER2-mut BC: must have received a prior CDK4/6 inhibitor. Pts must be ≥18 years old, with ECOG PS ≤1, adequate hepatic, hematological, renal, coagulation, and cardiac function, and no prior HER2-directed therapy (except Tras for uterine serous carcinoma). For eligibility, HER2 alterations can be demonstrated by HER2+ in tumor tissue by prior IHC/ISH (IHC 3+/signal ratio ≥2.0 or gene copy number >6), or by HER2 amplification/mutation in a prior or on-study NGS assay of ctDNA or prior tissue NGS assay. Pts with HER2+ disease will be enrolled in cohorts for cervical, uterine, biliary tract, and urothelial cancers, non-squamous NSCLC, and other solid tumors (except GEC, BC, and CRC). Pts with HER2-mut disease will be enrolled in cohorts for non-squamous NSCLC, BC, and other solid tumors. Except for solid tumor and BC cohorts, 12 RECIST 1.1 evaluable pts will be enrolled in each cohort. If ≥2 responses are observed, the cohort will be expanded to a total of 30 pts. Other solid tumor and BC cohorts will enroll 30 pts in a single stage. If justified, additional HER2+ or HER2-mut disease-specific cohorts may be opened. Approximately 162-270 pts are planned. The primary objective is antitumor activity in each cohort, with confirmed ORR per investigator as primary endpoint, and disease control rate, duration of response, PFS, and OS as secondary endpoints. Pts will receive TUC 300 mg orally twice daily and Tras 8 mg/kg IV on Cycle 1 Day 1 and 6 mg/kg q21 days from Cycle 2 Day 1. HR+ BC pts will also receive fulvestrant 500 mg IM every 4 weeks and C1 D15. Disease assessments per RECIST 1.1 will occur q6 weeks for 24 weeks, then q12 weeks. TUC PK will be evaluated in all pts in Cycles 2-6. QoL is evaluated q2 cycle using EQ-5D-5L. Sites are open in the US; EU and Asia will be opened. Enrollment began in Dec 2020. Clinical trial information: NCT04579380.

In this study we aim to examine gene–environment interactions (GxEs) between genes involved with estrogen metabolism and environmental factors related to estrogen exposure. GxE analyses were conducted with 1970 Korean breast cancer cases and 2052 controls in the case-control study, the Seoul Breast Cancer Study (SEBCS). A total of 11,555 SNPs from the 137 candidate genes were included in the GxE analyses with eight established environmental factors. A replication test was conducted by using an independent population from the Breast Cancer Association Consortium (BCAC), with 62,485 Europeans and 9047 Asians. The GxE tests were performed by using two-step methods in GxEScan software. Two interactions were found in the SEBCS. The first interaction was shown between rs13035764 of NCOA1 and age at menarche in the GE|2df model (p-2df = 1.2 × 10−3). The age at menarche before 14 years old was associated with the high risk of breast cancer, and the risk was higher when subjects had homozygous minor allele G. The second GxE was shown between rs851998 near ESR1 and height in the GE|2df model (p-2df = 1.1 × 10−4). Height taller than 160 cm was associated with a high risk of breast cancer, and the risk increased when the minor allele was added. The findings were not replicated in the BCAC. These results would suggest specificity in Koreans for breast cancer risk.