Rapid improvement in spinal pain in patients with axial spondyloarthritis treated with secukinumab: primary results from a randomized controlled phase-IIIb trial.

BACKGROUND: This study aimed to evaluate the efficacy and safety of secukinumab 150 mg compared with placebo in the management of spinal pain and disease activity in patients with axial spondyloarthritis (axSpA) at Week 8 and up to Week 24. METHODS: Patients (n = 380) with active axSpA were randomized (3:1) to secukinumab 150 mg (Group A) or placebo (Group B). At Week 8, patients from Group A with an average spinal pain score <4 were defined as responders and were re-assigned to secukinumab 150 mg (Arm A1); whereas non-responders were re-randomized to secukinumab 150/300 mg (Arm A2/A3). Patients from Group B were re-randomized (1:1) to secukinumab 150/300 mg (Arm B1/B2). RESULTS: At Week 8, the odds of achieving an average spinal pain score of <4 were significantly higher for patients on secukinumab 150 mg than for patients on placebo (odds ratio (OR): 1.89; 95% confidence interval (CI): 1.08-3.33; p = 0.0264). Further reductions in spinal pain were observed across treatment groups up to Week 24. Pronounced improvements were also observed in other disease activity measurements, such as Bath Ankylosing Spondylitis Disease Activity Index and Ankylosing Spondylitis Disease Activity Score. Responders from Group A showed the highest improvements for all measured parameters of spinal pain compared with the other arms. No new or unexpected safety signals were observed. CONCLUSION: Secukinumab provided rapid and significant improvement in spinal pain at Week 8 which was sustained or increased further up to Week 24 in patients with axSpA. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03136861. Registered May 2, 2017.

Secukinumab in patients with psoriatic arthritis and axial manifestations: results from the double-blind, randomised, phase 3 MAXIMISE trial.

OBJECTIVES: MAXIMISE (Managing AXIal Manifestations in psorIatic arthritis with SEcukinumab) trial was designed to evaluate the efficacy of secukinumab in the management of axial manifestations of psoriatic arthritis (PsA). METHODS: This phase 3b, double-blind, placebo-controlled, multi-centre 52-week trial included patients (≥18 years) diagnosed with PsA and classified by ClASsification criteria for Psoriatic Arthritis (CASPAR) criteria, with spinal pain Visual Analogue Score ≥40/100 and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score ≥4 despite use of at least two non-steroidal anti-inflammatory drugs (NSAIDs). Patients were randomised (1:1:1) to secukinumab 300 mg, secukinumab 150 mg or placebo weekly for 4 weeks and every 4 weeks thereafter. At week 12, placebo patients were re-randomised to secukinumab 300/150 mg. Primary endpoint was ASAS20 (Assessment of SpondyloArthritis international Society) response with secukinumab 300 mg at week 12. RESULTS: Patients were randomly assigned; 167 to secukinumab 300 mg, 165 to secukinumab 150 mg and 166 to placebo. Secukinumab 300 mg and 150 mg significantly improved ASAS20 response versus placebo at week 12 (63% and 66% vs 31% placebo). The OR (95% CI) comparing secukinumab 300 mg and 150 mg versus placebo, using a logistic regression model after multiple imputation, was 3.8 (2.4 and 6.1) and 4.4 (2.7 and 7.0; p<0.0001). CONCLUSIONS: Secukinumab 300 mg and 150 mg provided significant improvement in signs and symptoms of axial disease compared with placebo in patients with PsA and axial manifestations with inadequate response to NSAIDs. TRIAL REGISTRATION NUMBER: NCT02721966.

Secukinumab for moderate-to-severe palmoplantar pustular psoriasis: Results of the 2PRECISE study.

BACKGROUND: Palmoplantar pustular psoriasis (PPP) is a debilitating disease of the palms and/or soles that is resistant to treatment. Secukinumab, an anti-interleukin 17A monoclonal antibody, is highly efficacious in the treatment of moderate-to-severe psoriasis. OBJECTIVE: The primary objective was to determine the rate of achievement of a 75% improvement from baseline in Palmoplantar Psoriasis Area and Severity Index (PPPASI75) with secukinumab at week 16 versus with placebo (at a 2.5% significance level). METHODS: 2PRECISE was a phase 3b multicenter, randomized, double-blind, placebo-controlled, parallel-group study comparing treatment with 300 mg of secukinumab (n = 79), 150 mg of secukinumab (n = 80), and placebo (n = 78) in subjects with moderate-to-severe PPP over a period of 52 weeks. RESULTS: The primary end point was not met. At week 16, 26.6% of subjects treated with 300 mg of secukinumab achieved PPPASI75 versus 14.1% of those who received placebo (P = .0411) (odds ratio, 2.62; 95% confidence interval, 1.04-6.60). At week 52, 41.8% of subjects treated with 300 mg of secukinumab had achieved ppPASI75. More Dermatology Life Quality Index responses of 0 or 1 were achieved with 300 mg of secukinumab (13.0%) than with placebo (4.3%) at week 16. At week 52, 43.1% of subjects receiving 300 mg of secukinumab had a Dermatology Life Quality Index response of 0 or 1. No unexpected adverse events were observed. LIMITATIONS: Small sample size and characteristics of the PPP disease course. CONCLUSION: Patients with PPP who were treated with secukinumab, 300 mg, showed benefit in terms of PPPASI75 responses over 52 weeks and improved quality of life.

The need for comparative data in spondyloarthritis.

Spondyloarthritis comprises a group of inflammatory diseases, characterised by inflammation within axial joints and/or peripheral arthritis, enthesitis and dactylitis. An increasing number of biologic treatments, including biosimilars, are available for the treatment of spondyloarthritis. Although there are a growing number of randomised controlled trials assessing treatments in spondyloarthritis, there is a paucity of data from head-to-head studies. Comparative data are required so that clinicians and payers have the level of evidence required to inform clinical decision-making and health economic assessments. In the absence of head-to-head studies, statistical methods such as network meta-analyses and matching-adjusted indirect comparisons (MAICs) are used for assessing comparative effectiveness.Network meta-analysis can be used to compare treatments for trials using a common comparator (e.g. placebo); however, for those without a common comparator or where considerable heterogeneity exists between the study populations, a MAIC that controls for differences in study design and baseline patient characteristics may be used. MAICs, unlike network meta-analyses, are of value for longer-term comparisons beyond the placebo-controlled phase of clinical trials, which is important for chronic diseases requiring long-term treatment, like spondyloarthritis. At present, there are a number of limitations that restrict the effectiveness of MAIC, such as the poor availability of individual patient-level data from trials, which results in patient-level data from one trial being compared with published whole-population data from another. Despite these limitations, drug reimbursement agencies are increasingly accepting MAIC as a means of comparative effectiveness and greater methodological guidance is needed.This report highlights a number of challenges that are specific to conducting comparative studies like MAIC in spondyloarthritis, including disease heterogeneity, the paucity of biomarkers and the duration of studies required for radiographic endpoints in this slow-progressing disease.

Emx3 is required for the differentiation of dorsal telencephalic neurons.

emx3 is first expressed in prospective telencephalic cells at the anterior border of the zebrafish neural plate. Knockdown of Emx3 function by morpholino reduces the expression of markers specific to dorsal telencephalon, and impairs axon tract formation. Rescue of both early and late markers requires low-level expression of emx3 at the one- or two-somite stage. Higher emx3 expression levels cause dorsal telencephalic markers to expand ventrally, which points to a possible role of emx3 in specifying dorsal telencephalon and a potential new function for Wnt/beta-catenin pathway activation. In contrast to mice, where Emx2 plays a major role in dorsal telencephalic development, knockdown of zebrafish Emx2 apparently does not affect telencephalic development. Similarly, Emx1 knockdown has little effect. Previously, emx3 was thought to be fish-specific. However, we found all three emx orthologs in Xenopus tropicalis and opossum (Monodelphis domestica) genomes, indicating that emx3 was present in an ancestral tetrapod genome.

The translocator maintenance protein Tam41 is required for mitochondrial cardiolipin biosynthesis.

The mitochondrial inner membrane contains different translocator systems for the import of presequence-carrying proteins and carrier proteins. The translocator assembly and maintenance protein 41 (Tam41/mitochondrial matrix protein 37) was identified as a new member of the mitochondrial protein translocator systems by its role in maintaining the integrity and activity of the presequence translocase of the inner membrane (TIM23 complex). Here we demonstrate that the assembly of proteins imported by the carrier translocase, TIM22 complex, is even more strongly affected by the lack of Tam41. Moreover, respiratory chain supercomplexes and the inner membrane potential are impaired by lack of Tam41. The phenotype of Tam41-deficient mitochondria thus resembles that of mitochondria lacking cardiolipin. Indeed, we found that Tam41 is required for the biosynthesis of the dimeric phospholipid cardiolipin. The pleiotropic effects of the translocator maintenance protein on preprotein import and respiratory chain can be attributed to its role in biosynthesis of mitochondrial cardiolipin.

The morphology proteins Mdm12/Mmm1 function in the major beta-barrel assembly pathway of mitochondria.

The beta-barrel proteins of mitochondria are synthesized on cytosolic ribosomes. The proteins are imported by the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It has been assumed that the SAM(core) complex with the subunits Sam35, Sam37 and Sam50 represents the last import stage common to all beta-barrel proteins, followed by splitting in a Tom40-specific route and a route for other beta-barrel proteins. We have identified new components of the beta-barrel assembly machinery and show that the major beta-barrel pathway extends beyond SAM(core). Mdm12/Mmm1 function after SAM(core) yet before splitting of the major pathway. Mdm12/Mmm1 have been known for their role in maintenance of mitochondrial morphology but we reveal assembly of beta-barrel proteins as their primary function. Moreover, Mdm10, which functions in the Tom40-specific route, can associate with SAM(core) as well as Mdm12/Mmm1 to form distinct assembly complexes, indicating a dynamic exchange between the machineries governing mitochondrial beta-barrel assembly. We conclude that assembly of mitochondrial beta-barrel proteins represents a major function of the morphology proteins Mdm12/Mmm1.

Mitochondrial preprotein translocases as dynamic molecular machines.

Proteomic studies have demonstrated that yeast mitochondria contain roughly 1000 different proteins. Only eight of these proteins are encoded by the mitochondrial genome and are synthesized on mitochondrial ribosomes. The remaining 99% of mitochondrial precursors are encoded within the nuclear genome and after their synthesis on cytosolic ribosomes must be imported into the organelle. Targeting of these proteins to mitochondria and their import into one of the four mitochondrial subcompartments--outer membrane, intermembrane space (IMS), inner membrane and matrix--requires various membrane-embedded protein translocases, as well as numerous chaperones and cochaperones in the aqueous compartments. During the last years, several novel protein components involved in the import and assembly of mitochondrial proteins have been identified. The picture that emerges from these exciting new findings is that of highly dynamic import machineries, rather than of regulated, but static protein complexes. In this review, we will give an overview on the recent progress in our understanding of mitochondrial protein import. We will focus on the presequence translocase of the inner mitochondrial membrane, the TIM23 complex and the presequence translocase-associated motor, the PAM complex. These two molecular machineries mediate the multistep import of preproteins with cleavable N-terminal signal sequences into the matrix or inner membrane of mitochondria.

Mitochondrial protein sorting: differentiation of beta-barrel assembly by Tom7-mediated segregation of Mdm10.

The mitochondrial outer membrane contains two distinct machineries for protein import and protein sorting that function in a sequential manner: the general translocase of the outer membrane (TOM complex) and the sorting and assembly machinery (SAM complex), which is dedicated to beta-barrel proteins. The SAM(core) complex consists of three subunits, Sam35, Sam37, and Sam50, that can associate with a fourth subunit, the morphology component Mdm10, to form the SAM(holo) complex. Whereas the SAM(core) complex is required for the biogenesis of all beta-barrel proteins, Mdm10 and the SAM(holo) complex play a selective role in beta-barrel biogenesis by promoting assembly of Tom40 but not of porin. We report that Tom7, a conserved subunit of the TOM complex, functions in an antagonistic manner to Mdm10 in biogenesis of Tom40 and porin. We show that Tom7 promotes segregation of Mdm10 from the SAM(holo) complex into a low molecular mass form. Upon deletion of Tom7, the fraction of Mdm10 in the SAM(holo) complex is significantly increased, explaining the opposing functions of Tom7 and Mdm10 in beta-barrel sorting. Thus the role of Tom7 is not limited to the TOM complex. Tom7 functions in mitochondrial protein biogenesis by a new mechanism, segregation of a sorting component, leading to a differentiation of beta-barrel assembly.

Mitochondrial morphology and protein import--a tight connection?

Although the field of mitochondrial protein import and assembly may have initially been viewed as a completely distinct area of investigation to that of mitochondrial morphology and dynamics, recent findings have noted a clear influence on organelle morphology by perturbations in protein import pathways. This review aims to provide an overview of the mitochondrial import machinery in context of the recent link between translocation components and organelle structure, in addition to conferring the questions and challenges that have surfaced due to these observations.

The essential mitochondrial protein Erv1 cooperates with Mia40 in biogenesis of intermembrane space proteins.

The proteins of the mitochondrial intermembrane space (IMS) are encoded by nuclear genes and synthesized on cytosolic ribosomes. While some IMS proteins are imported by the classical presequence pathway that involves the membrane potential deltapsi across the inner mitochondrial membrane and proteolytic processing to release the mature protein to the IMS, the import of numerous small IMS proteins is independent of a deltapsi and does not include proteolytic processing. The biogenesis of small IMS proteins requires an essential mitochondrial IMS import and assembly protein, termed Mia40. Here, we show that Erv1, a further essential IMS protein that has been reported to function as a sulfhydryl oxidase and participate in biogenesis of Fe/S proteins, is also required for the biogenesis of small IMS proteins. We generated a temperature-sensitive yeast mutant of Erv1 and observed a strong reduction of the levels of small IMS proteins upon shift of the cells to non-permissive temperature. Isolated erv1-2 mitochondria were selectively impaired in import of small IMS proteins while protein import pathways to other mitochondrial subcompartments were not affected. Small IMS precursor proteins remained associated with Mia40 in erv1-2 mitochondria and were not assembled into mature oligomeric complexes. Moreover, Erv1 associated with Mia40 in a reductant-sensitive manner. We conclude that two essential proteins, Mia40 and Erv1, cooperate in the assembly pathway of small proteins of the mitochondrial IMS.

Inactivation of the mitochondrial heat shock protein zim17 leads to aggregation of matrix hsp70s followed by pleiotropic effects on morphology and protein biogenesis.

The biogenesis of mitochondrial matrix proteins involves the translocase of the outer membrane, the presequence translocase of the inner membrane and the presequence translocase-associated motor. The mitochondrial heat shock protein 70 (mtHsp70) forms the central core of the motor. Recent studies led to the identification of Zim17, a mitochondrial zinc finger motif protein that interacts with mtHsp70. Different views have been reported on the localization of Zim17 in the mitochondrial inner membrane or matrix. Depletion of Zim17 impairs several critical mitochondrial processes, leading to inhibition of protein import, defects of Fe/S protein biogenesis and aggregation of Hsp70s in the matrix. Additionally, we found that inactivation of Zim17 altered the morphology of mitochondria. These pleiotropic effects raise the question of the specific function of Zim17 in mitochondria. Here, we report that Zim17 is a heat shock protein of the mitochondrial matrix that is loosely associated with the inner membrane. To address the function of Zim17 in organello, we generated a temperature-sensitive mutant allele of the ZIM17 gene in yeast. Upon a short-term shift of the yeast mutant cells to a non-permissive temperature, matrix Hsp70s aggregated while protein import, Fe/S protein activity and mitochondrial morphology were not, or only mildly, affected. Only after a long-term shift to non-permissive temperature, were strong defects in protein import, Fe/S protein activity and mitochondrial morphology observed. These findings suggest that the heat shock protein Zim17 plays a specific role in preventing protein aggregation in the mitochondrial matrix, and that aggregation of Hsp70s causes pleiotropic effects on protein biogenesis and mitochondrial morphology.

The mitochondrial morphology protein Mdm10 functions in assembly of the preprotein translocase of the outer membrane.

The biogenesis of mitochondrial outer membrane proteins involves the general translocase of the outer membrane (TOM complex) and the sorting and assembly machinery (SAM complex). The two known subunits of the SAM complex, Mas37 and Sam50, are required for assembly of the abundant outer membrane proteins porin and Tom40. We have identified an unexpected subunit of the SAM complex, Mdm10, which is involved in maintenance of mitochondrial morphology. Mitochondria lacking Mdm10 are selectively impaired in the final steps of the assembly pathway of Tom40, including the association of Tom40 with the receptor Tom22 and small Tom proteins, while the biogenesis of porin is not affected. Yeast mutants of TOM40, MAS37, and SAM50 also show aberrant mitochondrial morphology. We conclude that Mdm10 plays a specific role in the biogenesis of the TOM complex, indicating a connection between the mitochondrial protein assembly apparatus and the machinery for maintenance of mitochondrial morphology.