AOZORA: long-term safety and joint health in paediatric persons with haemophilia A without factor VIII inhibitors receiving emicizumab - protocol for a multicentre, open-label, phase IV clinical study

INTRODUCTION

Persons with haemophilia A (PwHA) commonly experience regular bleeding into joints, which may result in joint damage and complications such as degenerative arthritis. Emicizumab has previously demonstrated efficacy in reducing the occurrence of joint bleeds and target joints, along with having a favourable safety profile; however, data on the long-term effects on joint health are lacking. The AOZORA study will evaluate the long-term safety and joint health of paediatric PwHA without factor (F)VIII inhibitors taking emicizumab; here, we report the details of the study protocol and baseline data.

METHODS AND ANALYSIS

AOZORA is a multicentre, open-label, phase IV clinical study in Japan that aims to enrol approximately 30 PwHA aged <12 years without FVIII inhibitors. The primary endpoints include a long-term safety evaluation of adverse events, laboratory test abnormalities and FVIII inhibitor development; and a long-term joint health assessment using MRI and the Hemophilia Joint Health Score. Exploratory endpoints include characterising participants' physical activities and the number of activity-related bleeds requiring coagulation factor treatment. Currently, 30 participants have been enrolled, including 20 emicizumab-naïve participants and 10 who transferred from HOHOEMI, a previous study in paediatric PwHA.

ETHICS AND DISSEMINATION

The AOZORA study was approved by the Institutional Review Boards of Nara Medical University and the St Marianna University Group. The study will be conducted in compliance with the Declaration of Helsinki, the standards stipulated in paragraph 3 of Article 14 and Article 80-2 of the Pharmaceuticals, Medical Devices and Other Therapeutic Products Act, the Ministerial Ordinance on Good Clinical Practice and the Ministerial Ordinance on Good Post-marketing Study Practice. Data will be published in peer-reviewed journals and presented at Global congresses.

TRIAL REGISTRATION NUMBER

JapicCTI-194701.

On-demand treatment with the iron chelator deferasirox is ineffective in preventing blood-induced joint damage in haemophilic mice

INTRODUCTION

Early intervention in the devastating process of haemophilic arthropathy (HA) is highly desirable, but no disease-modifying therapy is currently available. Considering the pivotal role of iron in the development of HA, iron chelation is considered a promising therapeutic approach. A previous study in haemophilic mice demonstrated that treatment with the iron chelator deferasirox (DFX) 8 weeks before joint bleed induction, attenuated cartilage damage upon blood exposure. However, in haemophilia patients this approach is not opportune given the unpredictable occurrence of hemarthroses.

AIM

To evaluate the effectiveness of on-demand DFX treatment, initiated immediately after joint bleed induction.

METHODS

A joint bleed was induced in 66 factor VIII-deficient mice by infra-patellar needle puncture. Mice were randomly assigned to treatment with either placebo (drinking water) or DFX (dissolved in drinking water) throughout the study. Five weeks after joint bleed induction, inflammation and cartilage damage were assessed histologically. Joints of ten bleed naive haemophilic mice served as controls.

RESULTS

A joint bleed resulted in significant inflammation and cartilage damage in the blood-exposed joint compared with those of control animals, in both the placebo and DFX group (all p = <.05). No differences in tibiofemoral or patellar inflammation (p = .305 and p = .787, respectively) nor cartilage damage (p = .265 and p = .802, respectively) were found between the blood-exposed joints of both treatment groups.

CONCLUSION

On-demand treatment with DFX does not prevent joint damage following blood exposure in haemophilic mice. DFX seems unable to reach the joint in time to exert its effect before the irreversible harmful process is initiated.

Proteoglycan synthesis rate as a novel method to measure blood-induced cartilage degeneration in non-haemophilic and haemophilic rats

INTRODUCTION

Haemophilic animal models are used to study blood-induced cartilage damage, but quantitative and sensitive outcome measures are needed.

AIM

To develop a novel quantitative method for detecting early cartilage degeneration in a haemophilic rat model of blood-induced joint damage.

METHODS

The ³⁵ Sulphate incorporation (³⁵ SO₄ ^2- assay) was applied to tibial and patellar cartilage of wild-type rats to quantify baseline proteoglycan synthesis and to evaluate the effect of 4-day blood exposure in vitro. Next, haemarthrosis was induced in 39 FVIII-deficient rats and characterized by changes in knee joint diameter and development of bone pathology (using micro-CT). Four- and 16-day posthaemarthrosis proteoglycan synthesis rate (PSR) was assessed using the ³⁵ SO₄ ^2- assay, with the contralateral knee as control.

RESULTS

In vitro, a decrease in PSR in tibial and patellar cartilage was demonstrated following blood exposure. In vivo, joint diameter and development of bone pathology confirmed successful induction of haemarthrosis. In the blood-exposed knee, tibial and patellar PSR was inhibited 4 and 16 days after induced haemarthrosis. Interestingly, at day 16 the proteoglycan synthesis in the contralateral knee was also inhibited to an extent correlating with that of the blood-exposed knee.

CONCLUSION

For the first time, early changes in cartilage matrix synthesis upon blood exposure were quantified with the ³⁵ SO₄ ^2- assay in a haemophilic rat model, establishing this assay as a novel method to study blood-induced cartilage damage.

Application of Cellular Technologies to the Experimental Treatment of Destructive Inflammatory Arthropathies

Introduction

The treatment of destructive inflammatory joint diseases (arthropathies) is one of the issues of current interest in modern medicine. In destructive inflammatory diseases, the regenerative ability of cartilaginous tissue proves to be inadequate for neogenesis of joints. The goal of this study is to determine the efficacy of bone marrow-derived mononuclear cell fraction (MNC) and multipotent mesenchymal stromal cells (MMSC) in the treatment of destructive inflammatory joint diseases.

Materials and methods

The study subjects consisted of 15 male rabbits weighing 3-4 kg with experimental destructive inflammatory knee joint disease. The test animals were divided into 3 groups: reference group without treatment, first test group - introduction of autologous MNC from rabbit bone marrow into the affected joint, and second test group - introduction of cultured MMSC from rabbit bone marrow into the joint.

Results

A morphological examination of the synovial membranes in the reference group on the 40th day of the experiment revealed chronic synovitis with destruction of synoviocytes, thickening and inflammatory infiltration of the underlying connective tissue (subintima). During examination of synovial membranes in the first test group the patches of thickened regenerating inner layer (intima) made up by large proliferating synoviocytes were observed. The layer of loose connective tissue (subintima) contained a large number of small blood vessels and was only slightly infiltrated by inflammatory cells. The morphological examination of synovial membranes in the second test group discovered thickened regenerating intimal layer sitting on hypertrophied subintima with dense vascular network. Elastic collagenous layers of synovial membrane adjoined proliferating elements in cartilage plates.

Conclusion

Both autologous MNC fraction and MMSC from bone marrow proved effectiveness in the treatment of destructive inflammatory joint diseases which stimulate neoangiogenesis. At the same time, it must be noted that the introduction of MMSC diminished destructive changes and accelerated proliferative process.