Responsiveness and meaningful thresholds of PROMIS pain interference, fatigue, and physical function forms in adults with idiopathic inflammatory myopathies: Report from the OMERACT Myositis Working Group

BACKGROUND

A series of qualitative studies conducted by the OMERACT Myositis Working Group identified pain interference, fatigue, and physical function as highly important life impact domains for adults with idiopathic inflammatory myositis (IIM). In this study, our goal was to assess the responsiveness and minimal important difference of PROMIS pain interference (6a), fatigue (7a), and physical function (8b).

METHODS

Adults with IIM from USA, Netherlands, Korea, Sweden, and Australia with two "clinical" visits were enrolled in this prospective study. Anchor questions on a Likert scale were collected at baseline, and manual muscle testing (MMT), physician and patient reported global disease activity, and PROMIS instruments were collected at both visits. Responsiveness was assessed with i) ANOVA, ii) paired t-test, effect size and standardized response mean, and iii) Pearson correlation. Minimal important difference (MID), minimal important change (MIC) and minimal detectable change (MDC) values were calculated.

RESULTS

114 patients with IIM (median age 60, 60 % female) completed both visits. Changes in PROMIS instruments were significantly different among anchor categories. Patients who reported improvement had a significant improvement in their PROMIS scores with at least medium effect size, while patients who reported worsening and stability did not show a significant change with weak effect size. PROMIS instruments had weak to moderate correlations with MMT, patient and physician global disease activity. MID was approximately 2-3 points for Pain Interference and 3-4 points for Fatigue and Physical Function forms based on the method used. MIC was approximately 4-5 for improvement of all the instruments, while MDC was 1.7-2 points for Pain Interference and Physical Function and 3.2-3.9 for Fatigue.

CONCLUSION

This study provides evidence towards the responsiveness of the PROMIS instruments in a large international prospective cohort of adults with IIM supporting their use as PROMs in adult myositis.

Abstract 3862: AB474, a potent orally bioavailable inhibitor of arginase, for the treatment of cancer

Introduction: It has been demonstrated that myeloid derived suppressor cells (MDSCs) have a direct role in tumor immune evasion, and increased MDSCs are associated with reduced overall survival in several types of cancer. Elevated levels of circulating MDSCs have been shown to correlate with a blunted response to checkpoint blockade. MDSCs secrete arginase, which depletes arginine, leading to decreased T cell activity and a suppressed anti-tumor response. Here we will present the characterization of AB474, a highly potent small molecule inhibitor of arginase.

Methods: Arginase inhibition was measured using a coupled enzyme assay in the presence and absence of both mouse and human serum. IC50 was determined in buffer, human plasma, and serum by LC-MS/MS quantification of ornithine, while plasma protein binding was determined by equilibrium dialysis. Tumor transcript analysis was performed on homogenized whole murine tumors using Taqman probes. Arginase inhibition by AB474 was tested on human CD4 and CD8 T cells, with proliferation and effector functions being determined in the presence of recombinant and endogenous human ARG1. Assays were performed using standard CD2/CD3/CD28 activation conditions: proliferation was measured by flow cytometry, and IFNγ secretion by ELISA.

Results: AB474 inhibits arginase with low-nanomolar potency. It effectively inhibits both recombinant and endogenous arginase, while displaying low plasma protein binding across species. Pharmacokinetic characterization of AB474 demonstrated oral bioavailability in both mice and rats, displaying qualities compatible with human dosing. Measuring transcript of Arg1 in murine tumor models revealed expression in both tumor and immune compartments. Flow cytometry analysis shows ARG1+ MDSCs exist in both the tumor and periphery, with higher expression levels seen in Ly6c+ mMDSC populations. Consistent with the elevation of arginase in tumor-bearing mice, levels of arginine are decreased when compared to naïve littermates. Addition of arginase to activated CD4 or CD8 T-cells results in a significant suppression of proliferation, CD3 expression, and IFNγ secretion. Addition of AB474 results in a significant restoration of normal T cell effector functions (P < 0.001).

Conclusions: AB474 is a potent orally bioavailable inhibitor of arginase. Inhibition of arginase will block one of the primary immune-suppressive functions of MDSCs resulting in restored T cell activation and anti-tumor responses.

Citation Format: Sterling C. Eckard, Yu Chen, Dana Piovesan, Nell Narasappa, Timothy W. Park, Jarek Kalisiak, Eric T. Newcomb, Manmohan R. Leleti, Divyank Soni, Elaine Ginn, Jie Chen, Dan DiRenzo, Kristen Zhang, Lixia Jin, Stephen W. Young, Matthew J. Walters, Ulrike Schindler, Jay P. Powers. AB474, a potent orally bioavailable inhibitor of arginase, for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3862.

Conservative management of primary non-refluxing megaureter during the first year of life: A longitudinal observational study

INTRODUCTION

There is a lack of prospective studies that include a selected population of patients with primary non-refluxing megaureter (PM). Thus, a longitudinal observational study was designed to follow from birth a selected population of children with PM; all were antenatally diagnosed. In this paper, the outcomes observed in the first year of life are presented.

OBJECTIVE

The primary aim was to follow the natural history of PM. The secondary aim was to monitor the onset of any potential complications such as urinary tract infections (UTIs), need for hospitalization and need for surgical correction.

STUDY DESIGN

All children with antenatally diagnosed PM, born between January 2007 and December 2013, were prospectively followed with observational management: renal ultrasonography and clinical evaluation on a 3-month basis; urinalysis and culture in case of symptoms; and mercaptoacetyltriglycine (MAG3) nuclear scan once older than 1 month. Children presenting at birth with mild urinary tract dilatation were included in Group A; those with moderate-to-severe dilatation were included in Group B. Continuous antibiotic prophylaxis (CAP) was administered to Group B.

RESULTS

Forty-seven children (44 males, three females) with 58 PM were included in the study. The participants and their corresponding outcomes are shown in the summary Table. The presence of obstruction at renogram was a significant predictor of UTIs and hospitalization.

DISCUSSION

The strengths of this study were its prospective nature and its very consistent population. A limitation was the lack of control groups. The results regarding the negligible incidence of complications in Group A and the residual incidence of febrile UTIs (20%) and hospitalization (17%) in Group B, even with CAP, are in line with previous literature. In contrast, there was a higher risk of UTIs observed in children aged older than 6 months.

CONCLUSIONS

Resolution or improvement is expected in all cases of PM with mild postnatal dilatation, and close to 60% of those with moderate or severe dilatation. Surgery is rarely performed on children younger than 1 year of age. It is safe to observe children with mild urinary tract dilatation without CAP, because the incidence of UTIs is negligible. In those presenting with moderate or severe urinary tract dilatation, despite CAP, a residual incidence of UTIs is seen, and symptomatic patients often require hospitalization. However, UTIs are well tolerated and do not seem to modify outcome. Cases showing obstruction on the MAG3 scan seem to be at higher risk of UTIs and hospitalization.

TGF-β/Smad3 inhibit vascular smooth muscle cell apoptosis through an autocrine signaling mechanism involving VEGF-A

We have previously shown that in the presence of elevated Smad3, transforming growth factor-β (TGF-β) transforms from an inhibitor to a stimulant of vascular smooth muscle cell (SMC) proliferation and intimal hyperplasia (IH). Here we identify a novel mechanism through which TGF-β/Smad3 also exacerbates IH by inhibiting SMC apoptosis. We found that TGF-β treatment led to inhibition of apoptosis in rat SMCs following viral expression of Smad3. Conditioned media from these cells when applied to naive SMCs recapitulated this effect, suggesting an autocrine pathway through a secreted factor. Gene array of TGF-β/Smad3-treated cells revealed enhanced expression of vascular endothelial growth factor (VEGF), a known inhibitor of endothelial cell apoptosis. We then evaluated whether VEGF is the secreted mediator responsible for TGF-β/Smad3 inhibition of SMC apoptosis. In TGF-β/Smad3-treated cells, VEGF mRNA and protein as well as VEGF secretion were increased. Moreover, recombinant VEGF-A inhibited SMC apoptosis and a VEGF-A-neutralizing antibody reversed the inhibitory effect of conditioned media on SMC apoptosis. Stimulation of SMCs with TGF-β led to the formation of a complex of Smad3 and hypoxia-inducible factor-1α (HIF-1α) that in turn activated the VEGF-A promoter and transcription. In rat carotid arteries following arterial injury, Smad3 and VEGF-A expression were upregulated. Moreover, Smad3 gene transfer further enhanced VEGF expression as well as inhibited SMC apoptosis. Finally, blocking either the VEGF receptor or Smad3 signaling in injured carotid arteries abrogated the inhibitory effect of Smad3 on vascular SMC apoptosis. Taken together, our study reveals that following angioplasty, elevation of both TGF-β and Smad3 leads to SMC secretion of VEGF-A that functions as an autocrine inhibitor of SMC apoptosis. This novel pathway provides further insights into the role of TGF-β in the development of IH.

Trm9-catalyzed tRNA modifications link translation to the DNA damage response

Transcriptional and posttranslational signals are known mechanisms that promote efficient responses to DNA damage. We have identified Saccharomyces cerevisiae tRNA methyltransferase 9 (Trm9) as an enzyme that prevents cell death via translational enhancement of DNA damage response proteins. Trm9 methylates the uridine wobble base of tRNAARG(UCU) and tRNAGLU(UUC). We used computational and molecular approaches to predict that Trm9 enhances the translation of some transcripts overrepresented with specific arginine and glutamic acid codons. We found that translation elongation factor 3 (YEF3) and the ribonucleotide reductase (RNR1 and RNR3) large subunits are overrepresented with specific arginine and glutamic acid codons, and we demonstrated that Trm9 significantly enhances Yef3, Rnr1, and Rnr3 protein levels. Additionally, we identified 425 genes, which included YEF3, RNR1, and RNR3, with a unique codon usage pattern linked to Trm9. We propose that Trm9-specific tRNA modifications enhance codon-specific translation elongation and promote increased levels of key damage response proteins.