Citations

Abstract Background Observational studies have shown higher folate consumption to be associated with lower risk of colorectal cancer (CRC). Understanding whether and how genetic risk factors interact with folate could further elucidate the underlying mechanism. Aggregating functionally relevant genetic variants in set-based variant testing has higher power to detect gene-environment (GxE) interactions and may provide information on the underlying biological pathway. Objective We investigated interactions between folate consumption and predicted gene expression on colorectal cancer risk across the genome. Methods We used variant weights from the PrediXcan models of colon tissue-specific gene expression as a priori variant information for a set-based GxE approach. We harmonized total folate intake (mcg/day) based on dietary intake and supplemental use across cohort and case-control studies and calculated sex and study specific quantiles. Analyses were performed using a mixed effects score tests for interactions between folate and genetically predicted expression of 4,839 genes with available genetically predicted expression. We meta-analyzed results across 23 studies for a total of 13,498 cases with colorectal tumors and 13,918 controls of European ancestry. Results We found suggestive evidence of interaction with folate intake for genes including glutathione S-Transferase Alpha 1 (GSTA1; p=4.3E-4), Tonsuko Like, DNA Repair Protein (TONSL; p=4.3E-4), and Aspartylglucosaminidase (AGA: p=4.5E-4). Glutathione is an antioxidant, preventing cellular damage and is a downstream metabolite of homocysteine and metabolized by GSTA1. TONSL is part of a complex that functions in the recovery of double strand breaks and AGA plays a role in lysosomal breakdown of glycoprotein. Conclusion We identified three genes involved in preventing or repairing DNA damage that may interact with folate consumption to alter CRC risk.

Abstract Background Treating COVID-19 infection in SOT is challenging due to long-term use of immunosuppressive agents. REM is the only FDA-approved anti-viral for SARS-COV-2 infection. DEX showed decrease in mortality in the Recovery Trial. COVID-19 treatment guidelines for SOT patients are the same as NTP despite limited literature on those outcomes. Our primary objective was to determine if 30-day mortality was different between SOT and NTP matched cohorts using these 2 drugs. The secondary objectives included comparisons of length of stay (LOS), days on mechanical ventilation (DMV), and the use of other treatment modalities. Methods We retrospectively collected data for hospitalized SOT and NTP, 18 years and older, with pcr-confirmed SARS-CoV-2 infection receiving REM and DEX from May 1, 2020, to October 10, 2020, at Mayo Clinic Florida. IRB approval was obtained. Descriptive statistics were used to analyze the data. Continuous variables were summarized as mean (standard deviation) or median (range) where appropriate, while categorical variables were reported as frequency (percentage). Results Of 80 patients who met the inclusion criteria, 28 were SOT, and 52 were NTP. The SOT cohort was subcategorized below: SOT patients were significantly younger than NTP (p < .001). Further, SOT patients had significantly longer LOS (p = 0.043) and more COVID-19 modalities (75% vs. 36.5%, p = 0.002) compared to NTP. Among the 28 SOT patients, 2 of them died within 30 days of admission, and among the 52 NTP patients, 7 of them died within 30 days. The 30-d survival estimate for SOT group is 92.9% (95% CI: 83.8% - 100.0%) and for NTP group is 86.5% (95% CI: 77.7% - 96.3%). The log-rank test was not significant between the groups (p=0.37), but the NTP has a worse survival curve from the figure below. SOT-NTP Survival Curve Conclusion SOT group was younger, had longer LOS, and more COVID-related modalities. The 30-d survival estimate for SOT group is 92.9% and for NTP group is 86.5%, but the survival curve for NTP was worse likely secondary to age. Use of REM & DEX in SOT recipients is a valid recommendation. Disclosures Claudia R. Libertin, MD, Gilead (Grant/Research Support)

Abstract Clinical significance of somatic gene variants needs to be comprehensively characterized for their diagnostic, prognostic and/or therapeutic actionability in patient management. However, challenges remain due to discrepancies in interpretation and reporting of these somatic variants among different testing labs. Therefore, standardized curation, clinical interpretation and reporting of somatic variants in hematologic cancers is critical. To address this issue, the Hematologic Cancer Taskforce (HCT), composed of 52 multi-disciplinary experts including oncologists, molecular pathologists, lab directors, genomic scientists and biocurators, was formed in January 2020 within the ClinGen Somatic Cancer Clinical Domain Working Group (CDWG) with a goal to undertake systematic curation and evidence-based clinical interpretation of genes/somatic variants associated with hematologic malignancies. In collaboration with the Clinical Interpretation of Variants in Cancer (CIViC) (civicdb.org) knowledgebase, HCT members curate, edit, and verify Evidence Items for each variant extracted from peer-reviewed publications. Monthly discussions based on these Evidence Items lead to the preparation of variant Assertions, which summarize the state of the field consensus variant interpretation and include tiering based on the AMP/ASCO/CAP guidelines (PMID: 27993330). FMS-like tyrosine kinase 3 (FLT3) encodes a class III receptor tyrosine kinase expressed in hematopoietic cells. FLT3 mutations, including both internal tandem duplication (ITD) and mutations in the tyrosine kinase domain (TKD), are the most common mutations in acute myeloid leukemia (AML), occurring in approximately 30% of all AML cases. Implementing FLT3 tyrosine kinase inhibitors (TKIs) in different treatment regimens for FLT3 mutated AML patients has led to significantly improved overall survival. Type I FLT3 inhibitors, including midostaurin, gilteritinib, sunitinib, lestaurtinib, and crenolanib, bind to the ATP-binding site when the receptor is in active conformation. Type II FLT3 inhibitors, including sorafenib, ponatinib, and quizartinib, interact with a hydrophobic region directly adjacent to the ATP-binding domain that is only accessible when the receptor is inactive, which prevents receptor activation. Generally in AML cells, type I FLT3 inhibitors prevent activity for both ITD and TKD mutations, while Type II inhibitors target ITD but lack efficiency against TKD mutations. The development of TKD mutations in AML cells with ITD have proved to be a mechanism of acquired, or secondary resistance to Type II FLT3 inhibitors. The HCT is piloting curation assessments of FLT3 alterations, including ITD, TKD and non-TKD variants, in AML. So far, the HCT has curated 75 evidence items for FLT3 somatic variants. FLT3-ITD, as well as D835 and I836 were asserted as tier 1 level A variants based on the prediction of response to gilteritinib in relapsed/refractory AML (PMIDs: 27993330, 31665578, 28645776, 28516360, 27908881). Recent curation activities are focused on FLT3 D839G and N676K, as clinical trials using large AML patient cohorts are lacking in their ability to validate drug response/resistance associations of these two TKD variants due to their low frequency. Functional studies showed both variants result in increased proliferation and protection from apoptosis, supporting the oncogenic potential of these two variants (PMIDs: 26891877, 2468088). FLT3 D839G combined with ITD confers resistance to pexidartinib and ponatinib, both Type II FLT3 inhibitors (PMIDs: 25847190, 23430109). FLT3 N676K predicts response to the Type I FLT3 inhibitor, gilteritinib, when N676K is present alone or in combination with ITD. Interestingly, FLT3 N676K in the absence of ITD predicts response to sorafenib, a Type II FLT3 inhibitor (PMIDs: 32040554, 32984009). However, these results are mostly derived from in vitro studies. Two separate Tier II, Level D Assertions have been submitted for FLT3-ITD&D839G for its response to pexidartinib and ponatinib, and more evidence is being collected to form an Assertion for FLT3 N676K. The complexity of the prediction of response/resistance associated with FLT3 D839G and N676K supports the importance of evidence-based curation and collection for these variants in the context of the overall mutation profile, disease context and specific FLT3 TKIs to clearly define their clinical impact. Disclosures Pullarkat: Stemline Therapeutics: Honoraria.

ABSTRACT Background Nephrolithiasis in allograft kidneys is rare, but this diagnosis may lead to allograft complications and patient morbidity. Previous studies that have evaluated nephrolithiasis posttransplant have focused on surgical stone management, with limited data on urine metabolic risk factors and the presence of stones after follow-up. Methods We retrospectively evaluated kidney transplant recipients who were diagnosed with transplant nephrolithiasis between 2009 and 2019. Computed tomography and ultrasound imaging were used to confirm stone presence. Results The incidence of allograft kidney stone formation was 0.86% of 6548 kidney transplant recipients. Of the 56 cases identified, 17 (30%) had a pretransplant history of nephrolithiasis. Only four (7%) patients received a known kidney stone at the time of allograft implantation. Of the 56 cases, 34 had a 24-h supersaturation study. The urine supersaturation study showed 32 patients (94%) had a urine citrate of <450 mg excreted in 24 h (median 124.5 mg/24 h, reference range >500 mg/24 h), along with 22 patients (61%) having a urine oxalate excretion of ≥30 mg in 24 h (median 34.4 mg/24 h, reference range <30 mg/24 h). Calcium oxalate composition was most common (91% with >1 supersaturation for calcium oxalate crystals), with normal median urine calcium levels (median urine calcium 103.5 mg/24 h, reference range <200 mg/24 h). After a 4-year follow-up, 50% (n = 28) required surgical intervention and 43 (77%) patients continued to have evidence of transplant nephrolithiasis on imaging. Conclusions This is the largest study of transplant nephrolithiasis confirming that hypocitraturia and hyperoxaluria were the most significant urine metabolic risk factors associated with allograft nephrolithiasis and that hyperoxaluria was the most prevalent driver for calcium oxalate stone composition. Our study is first to show low stone-free rates at the last follow-up and a significant proportion requiring surgical intervention.

Abstract Proximity labeling catalyzed by promiscuous enzymes, such as APEX2, has emerged as a powerful approach to characterize multiprotein complexes and protein–protein interactions. However, current methods depend on the expression of exogenous fusion proteins and cannot be applied to identify proteins surrounding post-translationally modified proteins. To address this limitation, we developed a new method to label proximal proteins of interest by antibody-mediated protein A-ascorbate peroxidase 2 (pA-APEX2) labeling (AMAPEX). In this method, a modified protein is bound in situ by a specific antibody, which then tethers a pA-APEX2 fusion protein. Activation of APEX2 labels the nearby proteins with biotin; the biotinylated proteins are then purified using streptavidin beads and identified by mass spectrometry. We demonstrated the utility of this approach by profiling the proximal proteins of histone modifications including H3K27me3, H3K9me3, H3K4me3, H4K5ac, and H4K12ac, as well as verifying the co-localization of these identified proteins with bait proteins by published ChIP-seq analysis and nucleosome immunoprecipitation. Overall, AMAPEX is an efficient method to identify proteins that are proximal to modified histones.

Abstract Although chimeric antigen receptor T (CART)–cell therapy has been successful in treating certain hematologic malignancies, wider adoption of CART-cell therapy is limited because of minimal activity in solid tumors and development of life-threatening toxicities, including cytokine release syndrome (CRS). There is a lack of a robust, clinically relevant imaging platform to monitor in vivo expansion and trafficking to tumor sites. To address this, we utilized the sodium iodide symporter (NIS) as a platform to image and track CART cells. We engineered CD19-directed and B-cell maturation antigen (BCMA)–directed CART cells to express NIS (NIS+CART19 and NIS+BCMA-CART, respectively) and tested the sensitivity of 18F-TFB-PET to detect trafficking and expansion in systemic and localized tumor models and in a CART-cell toxicity model. NIS+CART19 and NIS+BCMA-CART cells were generated through dual transduction with two vectors and demonstrated exclusive 125I uptake in vitro. 18F-TFB-PET detected NIS+CART cells in vivo to a sensitivity level of 40,000 cells. 18F-TFB-PET confirmed NIS+BCMA-CART-cell trafficking to the tumor sites in localized and systemic tumor models. In a xenograft model for CART-cell toxicity, 18F-TFB-PET revealed significant systemic uptake, correlating with CART-cell in vivo expansion, cytokine production, and development of CRS-associated clinical symptoms. NIS provides a sensitive, clinically applicable platform for CART-cell imaging with PET scan. 18F-TFB-PET detected CART-cell trafficking to tumor sites and in vivo expansion, correlating with the development of clinical and laboratory markers of CRS. These studies demonstrate a noninvasive, clinically relevant method to assess CART-cell functions in vivo.

Background: Among patients (pts) with coronary artery disease (CAD) who are candidates for coronary artery bypass graft surgery (CABG), a reduced ejection fraction (EF) identifies a high-risk group. The profile of pre-operative, intra-operative and post-operative factors contributing to 30 day (d) mortality in pts with low EF undergoing CABG has not been well characterized. Methods: The STICH trial enrolled 2136 pts with CAD amenable to CABG with an LVEF < 35% who were treated with medical therapy (MED) alone, MED with CABG, or with MED plus CABG and surgical ventricular resconstruction (SVR). Multivariable logistic regression models utilizing extensive baseline, intra-operative and post-operative care variables were developed to determine factors associated with mortality at 30d in a landmark analysis among pts surviving the first 36 hours (h). Results: Among those enrolled, 1460 pts received CABG; 673 (46.1%) on pump, 160 (11.0%) off pump, 132 (9.0%) with a mitral valve procedure (MVR), 393 (26.9%) with SVR, and 102 (7.0%) received CABG with SVR and MVR. Mortality in the operating room (OR) was 0.3 %, within the first 36h was 1.0%, and at 30d was 5.1%. The rate of in-hospital acute myocardial infarction was 0.8%, stroke 1.6%, mediastinitis 1.7%, worsening renal insufficiency 8.4%, and return to OR was 6.9%. Inotropes were used in 43.6% and intra-aortic balloon pump in 18.6%. At 36h, 148 pts (10.2%) remained intubated. Among pts who survived to 36h, a robust multivariable model (Table, c-statistic 0.89) was developed to predict 30d mortality. A prolonged intubation time (>36h) was the strongest marker of 30d mortality (odds ratio 7.4, 95% CI 3.8, 14.5, p<0.0001). Conclusions: Among pts with ischemic heart failure, CABG can be performed with a low rate of complications and intra-operative mortality. Prolonged intubation time (>36h) after CABG is an integrated clincal marker that may serve to identify those pts with the least likelihood of survival to 30d.