Providing culturally responsive care in a pediatric setting: are our trainees ready?

BACKGROUND

Extensive data consistently demonstrates inequities in access and delivery of healthcare for patients from historically marginalized populations, resulting in poorer health outcomes. To address this systemic oppression in healthcare, it is necessary to embed principles of equity, diversity, and inclusion (EDI) at an early stage within medical education. This study aimed to assess pediatric trainees' perceived interest in EDI curricula as well as their confidence in applying this knowledge to provide culturally responsive care.

METHODS

An anonymous online survey was distributed to pediatric trainees at the University of Toronto. Closed-ended questions used a Likert scale to assess respondents' confidence and interest in providing culturally responsive care to patients. Open-ended questions explored trainees' perceptions of effective EDI learning modalities. A mixed methods approach was utilized, where quantitative data was summarized using descriptive statistics and descriptive content analysis was used to highlight themes within qualitative data.

RESULTS

116 pediatric trainees completed the survey, of which 72/116 (62%) were subspecialty residents/fellows and 44/116 (38%) were core residents. 97% of all responses agreed or strongly agreed that it was important to learn about providing culturally responsive care to patients from historically marginalized communities; however, many trainees lacked confidence in their knowledge of providing culturally responsive care (42%) and applying their knowledge in clinical practice (47%). Respondents identified direct clinical exposure through rotations, immersive experiences, and continuity clinics as effective EDI teaching modalities. Identified barriers included time constraints in the clinical environment, burnout, and lack of exposure to diverse patient populations.

CONCLUSION

Most pediatric trainees want to provide culturally responsive care to patients from historically marginalized communities, but do not feel confident in their knowledge to do so. Trainees value learning about EDI through direct clinical exposure and immersive experiences, rather than didactic lectures or modules. These study findings will be utilized to develop and implement an enhanced EDI education curriculum for pediatric trainees at the University of Toronto and other postgraduate residency programs.

A genome-wide CRISPR/Cas9 screen in acute myeloid leukemia cells identifies regulators of TAK-243 sensitivity

TAK-243 is a first-in-class inhibitor of ubiquitin-like modifier activating enzyme 1 that catalyzes ubiquitin activation, the first step in the ubiquitylation cascade. Based on its preclinical efficacy and tolerability, TAK-243 has been advanced to phase I clinical trials in advanced malignancies. Nonetheless, the determinants of TAK-243 sensitivity remain largely unknown. Here, we conducted a genome-wide CRISPR/Cas9 knockout screen in acute myeloid leukemia (AML) cells in the presence of TAK-243 to identify genes essential for TAK-243 action. We identified BEN domain-containing protein 3 (BEND3), a transcriptional repressor and a regulator of chromatin organization, as the top gene whose knockout confers resistance to TAK-243 in vitro and in vivo. Knockout of BEND3 dampened TAK-243 effects on ubiquitylation, proteotoxic stress, and DNA damage response. BEND3 knockout upregulated the ATP-binding cassette efflux transporter breast cancer resistance protein (BCRP; ABCG2) and reduced the intracellular levelsof TAK-243. TAK-243 sensitivity correlated with BCRP expression in cancer cell lines of different origins. Moreover, chemical inhibition and genetic knockdown of BCRP sensitized intrinsically resistant high-BCRP cells to TAK-243. Thus, our data demonstrate that BEND3 regulates the expression of BCRP for which TAK-243 is a substrate. Moreover, BCRP expression could serve as a predictor of TAK-243 sensitivity.

Abstract 6321: BEND3 modulates sensitivity to the UBA1 inhibitor TAK-243 by regulating expression of the multidrug transporter BCRP

TAK-243 (MLN7243) is a first-in-class inhibitor of the ubiquitin-activating enzyme (UBA1) that catalyzes the first step in the ubiquitylation cascade whereby proteins are tagged with mono- or poly-ubiquitin to induce their degradation or modify their functions. Based on its preclinical efficacy and tolerability, TAK-243 has entered phase 1 clinical trials in advanced malignancies. However, the determinants of sensitivity to TAK-243 remain largely unknown. Therefore, we conducted a positive-selection, genome-wide CRISPR/Cas9 knockout screen in OCI-AML2 cells followed by selection with lethal TAK-243 concentrations to identify genes essential for TAK-243 action. We identified BEN domain-containing protein 3 (BEND3), a transcriptional repressor and a regulator of chromatin organization, as the top gene whose knockout conferred resistance to TAK-243 (FDR = 0.0012). BEND3-targeting gRNAs were enriched up to 10,000-fold after selection with the drug. To validate the screen results, we independently knocked out BEND3 in OCI-AML2 cells and confirmed the resistance phenotype. In vivo, tumors of BEND3-knockout cells were resistant to TAK243 (20 mg/kg twice weekly) as opposed to control tumors that showed dramatic reductions in tumor growth rate. As assessed by immunoblotting, BEND3 knockout dampened TAK-243 effects on ubiquitylation, proteotoxic stress and DNA damage response. Mechanistically, BEND3 knockout upregulated the ABC efflux transporter breast cancer resistance protein (BCRP; ABCG2), and decreased intracellular levels of TAK-243. It also conferred partial cross-resistance to pevonedistat and TAK-981–related selective inhibitors of the NEDD8-activating enzyme (NAE) and the SUMO-activating enzyme (SAE), respectively, as well as known substrates of BCRP (mitoxantrone and doxorubicin). Finally, TAK-243 sensitivity strongly correlated with BCRP expression in a panel of 30 cancer cell lines of different origin, and chemical inhibition of BCRP but not P-gp sensitized intrinsically resistant high-BCRP cells to TAK-243. Thus, our data demonstrate that BEND3 regulates the expression of BCRP for which TAK-243 is a substrate. Moreover, BCRP expression could serve as a predictor of TAK-243 sensitivity.

Citation Format: Samir H. Barghout, Ahmed Aman, Zachary Blatman, Karen Arevalo, Geethu Thomas, Neil MacLean, Xiaoming Wang, Rose Hurren, Troy Ketela, Moustafa Abohawya, Taira Kiyota, Rima Al-Awar, Aaron D. Schimmer. BEND3 modulates sensitivity to the UBA1 inhibitor TAK-243 by regulating expression of the multidrug transporter BCRP [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6321.

1161 Baseline echocardiographic parameters associated with reintervention in children with aortic valve stenosis following balloon aortic valvuloplasty

Introduction

Aortic valve (AV) stenosis is the most common type of congenital left ventricular outflow tract obstruction. Short-term outcomes following balloon aortic valvuloplasty (BAV) including residual aortic stenosis, aortic insufficiency, and procedural complications have been established. The impact of pre-intervention AV characteristics on long-term outcomes has not been well studied.

Purpose

The aim of this study was to determine the relationship between the initial parameters on baseline echocardiogram and the time to reintervention in children with AV stenosis following BAV.

Methods

Children from the newborn period to 18 years of age with AV stenosis who underwent BAV from 2004-2012 were included. Patients with aortic insufficiency prior to BAV, complex congenital heart lesions, or less than two accessible follow-up echocardiograms were excluded. Baseline and serial echocardiographic data pertaining to aortic valve and LV size and function was retrospectively collected until December 2017 or until the first reintervention. Time to reintervention or death was evaluated.

Results

Among the 98 enrolled patients, the median [IQR] age at BAV was 2.8 months [0.2-75]. The median [IQR] duration of follow-up was 6.8 [1.9-9.0] years. Eighty-nine (83%) patients had bicuspid valve morphology and the median [IQR] peak-to-peak catheterization gradient prior to BAV was 49 [34-65] mmHg. The cumulative proportion [95% CI] of reintervention at 5 years following BAV was 33.7% [23.6%, 42.4%]. Primary indications for reintervention were aortic stenosis (57%), aortic insufficiency (14%), or mixed valve disease (30%). Reinterventions included repeat BAV (49%), AV repair (15%), and AV replacement (36%). Increased LVEF at baseline as well as increased mean LV circumferential strain at baseline were associated with decreased risk of reintervention (HR [95% CI] (1 unit increments): 0.974 [0.959-0.989], p < 0.001; 0.939 [0.884-0.997], p = 0.041 respectively). Increased AV annulus z-score was also associated with decreased risk of reintervention (HR [95% CI] (1 unit increments): 0.806 [0.698-0.93], p = 0.003).

Conclusions

Our results demonstrate that better left ventricular function at baseline, measured by LVEF and mean LV circumferential strain, is associated with a decreased risk of reintervention in neonates and children following BAV. We have also shown that a bigger AV annulus prior to BAV is associated with a decreased risk of reintervention.