Suppression of soluble T cell-associated proteins by an anti-interferon-α monoclonal antibody in adult patients with dermatomyositis or polymyositis

Abstract

Objective: The aim of this study was to identify serum markers that are modulated by an investigational anti-IFN-α mAb, sifalimumab, in adult DM or PM patients.

Methods: In a phase 1b clinical trial, sera were collected from a total of 48 DM or PM adult patients receiving either placebo for 3 months or sifalimumab for 6 months. Samples were tested for 128 selected proteins using a multiplex luminex immunoassay. Muscle biopsies from selected patients were stained for T cell infiltration using an anti-CD3 antibody.

Results: A robust overexpression of multiple serum proteins in DM or PM patients was observed, particularly in patients with an elevated baseline type I IFN gene signature in the blood or muscle. Neutralization of the type I IFN gene signature by sifalimumab resulted in coordinated suppression of T cell-related proteins such as soluble IL-2RA, TNF receptor 2 (TNFR2) and IL-18. Muscle biopsies from two patients with the highest serum protein suppression were selected and found to have a pronounced reduction of muscle T cell infiltration. Down-regulation of IL-2RA correlated with favourable manual muscle test 8 (MMT-8) alterations in sifalimumab-dosed patients.

Conclusion: A reduced level of multiple T cell-associated proteins after sifalimumab but not placebo administration suggests a suppressive effect of blocking type I IFN signalling on T cell activation and chemoattraction that may lead to a reduction of T cell infiltration in the muscle of myositis patients. Further, soluble IL-2RA changes from baseline may serve as a responsive and/or predictive marker for type I IFN-targeted therapy in adult DM or PM patients.

Keywords: T cell infiltration; dermatomyositis; polymyositis; soluble interleukin-2 receptor; type I interferon.

Fig. 1

Principal component analysis of HCs and myositis patients by serum protein levels PCA was performed using serum levels of 100 proteins across 25 HCs and 37 DM or PM patients with high (IFN-hi) and 11 patients with low (IFN-lo) type I IFN gene signature scores at baseline.

Fig. 2

Dysregulated ANGPT2, IL-2RA and TNFR2 levels in myositis patients (A) Serum angiopoietin-2 (ANGPT2) levels are higher in myositis patients with an elevated type I IFN signature score (IFN-hi) than in those without an elevated IFN signature (IFN-lo) and HCs. The y-axis represents the log₂-transformed serum level of ANGPT2 (ng/ml). (B) Myositis patients with ANGPT2 levels higher than the median value (>5.4 ng/ml) show significantly lower MMT-8 scores than those patients with ANGPT2 levels less than the median value (≤5.4 ng/ml). (C) IFN-hi patients show significantly higher soluble IL-2 receptor (IL-2RA) levels than IFN-lo patients and HCs. The y-axis represents the log₂-transformed serum levels of IL-2RA (pg/ml). (D) IFN-hi patients with IL-2RA levels higher than the upper limit of the normal range (2970 pg/ml) had significantly lower MMT-8 levels than IFN-lo patients with IL-2RA levels within the normal range. (E) Higher TNFR2 levels in IFN-hi patients than in IFN-lo patients and HCs. The y-axis represents the log₂-transformed serum levels of TNFR2 (ng/ml). (F) IFN-hi patients with TNFR2 levels higher than the upper limit of the normal range (11 ng/ml) had significantly lower MMT-8 levels than IFN-lo patients with TNFR2 levels within the normal range.

Fig. 3

Effects of sifalimumab administration on serum protein levels in myositis patients Eleven proteins had significantly reduced levels at day 98 after administration of sifalimumab in comparison with pre-treatment by paired t-test (BH P < 0.05). Percentage of change at day 98 relative to pre-treatment was scaled to have a mean of 0 and a s.d. of 1 for each protein across sifalimumab-administered patients. The black bar on the top denotes IFN-lo patients. The yellow bar shows four IFN-hi patients with ≤20% IFN target neutralization rate in blood. The blue bar denotes 20 IFN-hi patients with >20% IFN target neutralization rate in blood and two IFN-hi patients with >20% IFN neutralization rate in muscle (missing blood data). The normalized value of protein change at day 98 was used to order 11 proteins by the complete hierarchical clustering method.

Fig. 4

Suppression of muscle-infiltrating T cells by sifalimumab in myositis patients Immunohistochemistry results with anti-CD3 antibody are shown for paired muscle biopsies at baseline and day 98 after administration of sifalimumab from two patients with the highest reduction of T cell-associated proteins. Pronounced decreases in CD3 staining are seen at day 98 in both patients.

Fig. 5

Association between soluble IL-2RA reduction and favourable MMT-8 alterations after sifalimumab administration in myositis patients (A) Paired t-test shows that soluble IL-2 receptor (IL2RA) level at day 98 was significantly different from that at day 0 for patients with ≥15% MMT-8 improvement (n = 13; P < 0.05), but not those with <15% MMT-8 improvement (n = 23) at day 196 after administration of sifalimumab. The absolute change of IL-2RA level (pg/ml) at day 98 was also significantly different between two groups of patients with different MMT-8 improvement rates (P < 0.05). (B) MMT-8 level at day 196 was significantly different from that pre-treatment for patients with >30% reduction of IL-2RA level at day 98 (P < 0.001), but not those with <30% reduction of IL-2RA level at day 98 relative to pre-dose. Direct comparison of MMT-8 change between two groups of patients with different IL-2RA changes also showed a significant difference (P < 0.05).