Safety and efficacy of secukinumab in patients with giant cell arteritis (TitAIN): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

The treatment of giant cell arteritis with glucocorticoid-sparing agents is an unmet medical need. We evaluated the efficacy and safety of secukinumab, an anti-interleukin-17A monoclonal antibody, in patients with giant cell arteritis.

METHODS

We conducted a Bayesian randomised, parallel-group, double-blind, placebo-controlled, multicentre, phase 2 study at 11 clinics or hospitals in Germany. Patients aged 50 years or older with new-onset or relapsing giant cell arteritis who were naive to biological therapy and already receiving glucocorticoids with a prednisolone equivalent dose of 25-60 mg/day were eligible for inclusion. Participants were assigned (1:1) to receive 300 mg secukinumab or placebo subcutaneously once a week up to week 4 and every 4 weeks thereafter. In both treatment groups, prednisolone dose was tapered down to 0 mg over a 26-week period. Patients, investigator staff, and clinical trial team were masked to the treatment assignment. The primary endpoint was the median proportion (Bayesian analysis) of patients with sustained remission until week 28 in the full analysis set (ie, all patients who received at least one dose of assigned treatment, analysed according to treatment assigned at randomisation). Sustained remission rate of the placebo group from a previous trial of tocilizumab in patients with giant cell arteritis was used to derive the prior distribution of placebo sustained remission rate for the primary endpoint. The safety of secukinumab was assessed in the safety set (ie, all patients who received at least one dose of study treatment, analysed according to study treatment received). This trial is completed and is registered with ClinicalTrials.gov, NCT03765788.

FINDINGS

Of the 65 patients who were assessed for eligibility, 52 patients (median age 75 years [IQR 69-79]; 35 [67%] female and 17 [33%] male, 52 [100%] White) were enrolled between Jan 30, 2019 and March 30, 2020 and were randomly assigned to receive secukinumab (n=27) or placebo (n=25). Four of 27 patients in the secukinumab group and eight of 25 patients in the placebo group discontinued treatment by week 28 of the study. On the basis of the Bayesian analysis, the median proportion of patients in sustained remission until week 28 was 70% (95% credibility interval 52-85) in the secukinumab group versus 20% (12-30) in the placebo group. The incidence of adverse events was similar in the secukinumab (27 [100%] of 27 patients had any adverse event) and placebo groups (24 [96%] of 25 patients had any adverse event); the most common adverse events were hypertension (six [22%] of 27 patients in the secukinumab group and eight [32%] of 25 patients in the placebo group) and nasopharyngitis (five [19%] of 27 patients in the secukinumab group and five [20%] of 25 patients in the placebo group). Two patients (one in each group) died during the study, neither of which was considered to be related to study treatment.

INTERPRETATION

Patients with active giant cell arteritis had a higher sustained remission rate in the secukinumab group than in the placebo group at week 28, in combination with glucocorticoid taper regimen. Secukinumab was tolerated well with no new safety concerns. This proof-of-concept phase 2 study further supports the development of secukinumab as a treatment option for people with giant cell arteritis.

FUNDING

Novartis Pharma.

Efficacy and safety of secukinumab in patients with giant cell arteritis: study protocol for a randomized, parallel group, double-blind, placebo-controlled phase II trial

Background

One key pathological finding in giant cell arteritis (GCA) is the presence of interferon-gamma and interleukin (IL)-17 producing T helper (Th) 1 and Th17 cells in affected arteries. There is anecdotal evidence of successful induction and maintenance of remission with the monoclonal anti-IL-17A antibody secukinumab. Inhibition of IL-17A could therefore represent a potential new therapeutic option for the treatment of GCA.

Methods

This is a randomized, parallel-group, double-blind, placebo-controlled, multi-center, phase II study in which patients, treating physicians, and the associated clinical staff as well as the sponsor clinical team are blinded. It is designed to evaluate efficacy and safety of secukinumab compared to placebo in combination with an open-label prednisolone taper regimen. Patients included are naïve to biological therapy and have newly diagnosed or relapsing GCA. Fifty patients are randomly assigned in a 1:1 ratio to receive either 300 mg secukinumab or placebo subcutaneously at baseline, weeks 1, 2 and 3, and every 4 weeks from week 4. Patients in both treatment arms receive a 26-week prednisolone taper regimen. The study consists of a maximum 6-week screening period, a 52-week treatment period (including the 26-week tapering), and an 8-week safety follow-up, with primary and secondary endpoint assessments at week 28. Patients who do not achieve remission by week 12 experience a flare after remission or cannot adhere to the prednisolone tapering will enter the escape arm and receive prednisolone at a dose determined by the investigator’s clinical judgment. The blinded treatment is continued. Two optional imaging sub-studies are included (ultrasound and contrast-media enhanced magnetic resonance angiography [MRA]) to assess vessel wall inflammation and occlusion before and after treatment. The primary endpoint is the proportion of patients in sustained remission until week 28 in the secukinumab group compared to the proportion of patients in the placebo group. A Bayesian approach is applied.

Discussion

The trial design allows the first placebo-controlled data collection on the efficacy and safety of secukinumab in patients with GCA.

Trial registration

ClinicalTrials.gov NCT03765788. Registration on 5 December 2018, prospective registration, EudraCT number 2018-002610-12; clinical trial protocol number CAIN457ADE11C.

Identification of PDGF-BB binding to thymosin β4 by chemical cross-linking

INTRODUCTION

The purpose of our work was to identify unknown interaction partners of thymosin β4 (Tβ4). It was suggested that Tβ4 could be an antifibrotic drug for treatment of liver fibrogenesis, because Tβ4 prevents the platelet-derived growth factor-BB (PDGF-BB)-induced activation of hepatic stellate cells (HSCs). Very little information is available how Tβ4 counteracts the PDGF-BB-induced activation of HSCs. We propose the hypothesis that Tβ4 could bind directly to PDGF-BB and thereby reduce the concentration of free PDGF-BB available for binding to the PDGF-β receptor.

METHODS

To prove our suggestion of a direct interaction between Tβ4 and PDGF-BB, we carried out chemical as well as photochemical cross-linking experiments between the two pure proteins in vitro.

RESULTS

We identified an interaction between Tβ4 and PDGF-BB by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) cross-linking as well as through biotin label transfer using a bifunctional photoactivatable derivative of Tβ4. In an in vitro system, PDGF-BB was identified as the first extracellular partner interacting with Tβ4. This interaction could influence PDGF-BB binding to its receptor and abolish PDGF-BB-related effects.

CONCLUSION

Direct interaction of Tβ4 with extracellular factors should be considered as a potential mechanism to explain the pleiotropic effects of β-thymosins.

In vivo imaging using fluorescent antibodies to tumor necrosis factor predicts therapeutic response in Crohn's disease

As antibodies to tumor necrosis factor (TNF) suppress immune responses in Crohn's disease by binding to membrane-bound TNF (mTNF), we created a fluorescent antibody for molecular mTNF imaging in this disease. Topical antibody administration in 25 patients with Crohn's disease led to detection of intestinal mTNF(+) immune cells during confocal laser endomicroscopy. Patients with high numbers of mTNF(+) cells showed significantly higher short-term response rates (92%) at week 12 upon subsequent anti-TNF therapy as compared to patients with low amounts of mTNF(+) cells (15%). This clinical response in the former patients was sustained over a follow-up period of 1 year and was associated with mucosal healing observed in follow-up endoscopy. These data indicate that molecular imaging with fluorescent antibodies has the potential to predict therapeutic responses to biological treatment and can be used for personalized medicine in Crohn's disease and autoimmune or inflammatory disorders.

High-resolution HPLC-ESI-MS characterization of the contact sites of the actin-thymosin β(4) complex by chemical and enzymatic cross-linking

Thymosin β4 sequesters actin by formation of a 1:1 complex. This transient binding in the complex was stabilized by formation of covalent bonds using the cross-linking agents 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and a microbial transglutaminase. The localization of cross-linking sites was determined after separating the products using SDS-PAGE by tryptic in-gel digestion and high-resolution HPLC-ESI-MS. Three cross-linked fragments were identified after chemical cross-linking, indicating three contact sites. Because the cross-linked fragments were detected simultaneously with the corresponding non-cross-linked fragments, the three contact sites were not formed in parallel. K3 of thymosin β4 was cross-linked to E167 of actin, K18 or K19 of thymosin β4 to one of the first three amino acids of actin (DDE), and S43 of thymosin β4 to H40 of actin. The imidazole ring of histidine was proven to be an acyl acceptor for carbodiimide-mediated cross-linking. Molecular modeling proved an extended conformation of thymosin β4 along the subdomains 1 to 3 of actin. The enzymatic cross-linking using a microbial transglutaminase led to the formation of three cross-linking sites. Q41 of actin was cross-linked to K19 of thymosin β4, and K61 of actin to Q39 of thymosin β4. The third cross-linking site was identified between Q41 of actin and Q39 of thymosin β4, which are simultaneously cross-linked to K16, K18, or K19 of thymosin β4. When both cross-linking reactions are taken together, the complex formation of actin by thymosin β4 is more likely to be flexible than rigid and is localized along the subdomains 1 to 3 of actin.

Antibodies in research of thymosin β4: investigation of cross-reactivity and influence of fixatives

Antibodies against thymosin β4 are available from various sources and have been used in immunohistochemistry, ELISA, and Western blot analyses. None of these antibodies have been fully characterized for specificity and influence of fixation techniques. This presents a difficulty because many tissues express more than one member of the β-thymosin family; in addition, highly homologous sequences are typical elements of β-thymosins. It is also important to scrutinize the influence of fixatives on the antibody-binding capability. Fixatives such as formaldehyde are well known as cross-linking reagents. Chemical modifications within the thymosin β4 molecule might change the putative epitope recognized by the antibody. These considerations suggest that investigations on thymosin β4 antibodies available to the scientific community are important and necessary before any experiment can be performed to exclude cross-reactivity with other β-thymosins that are coexistent in the examined tissue and to prove antibody binding after fixation steps.

Identification of interaction partners of β-thymosins: application of thymosin β4 labeled by transglutaminase

In this review, we identify potential interaction partners of the β-thymosin family. The proteins of this family are highly conserved peptides in mammals and yet only one intracellular (G-actin) and one cell-surface protein (β subunit of F(1) -F(0) ATP synthase) were identified as interaction partners of thymosin β4. Cross-linking experiments may be a possible approach to discover additional proteins that interact with the β-thymosin family. It has previously been shown that thymosin β4 can be labeled at its glutaminyl residues with various cadaverines using tissue transglutaminase. Here, we illuminate recent results and give an outlook on upcoming work in the field.