Clinical Trial Details
— Status: Active, not recruiting
Administrative data
NCT number |
NCT03701789 |
Other study ID # |
BAREBONE2018 |
Secondary ID |
|
Status |
Active, not recruiting |
Phase |
Phase 3
|
First received |
|
Last updated |
|
Start date |
September 11, 2018 |
Est. completion date |
October 11, 2021 |
Study information
Verified date |
January 2021 |
Source |
University of Erlangen-Nürnberg Medical School |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
Patients with Rheumatoid Arthritis (RA) suffer systemic and peripheral bone loss. In this
study we aim to test the efficacy of in-label treatment with Baricitinib on the volumetric
bone mineral density in patients with RA over 52 weeks. Inclusion of RA patients comprises
pathologic volumetric bone mineral density measured by (High Resolution peripheral
quantitative Computed Tomomgraphy) HR-pQCT maging of finger joints.
Description:
Systemic and local bone loss is a pathognomonic feature of rheumatoid arthritis and can be
seen in a very early phase of the disease. Understanding the pathogenesis of rheumatoid
arthritis (RA) has advanced substantially in recent years. The mode of action of
immunosuppressive medication on pro-inflammatory cytokines, different cell types or
activation of cells is intensively studied and understood. In contrary, little is known on
how these medications influence bone damage in peripheral joints in terms of bone density,
bone microstructure, bone quality or erosions. This is due to different reasons. One factor
is the lack of suitable, user-independent imaging tools for outcome measurements. For
example, using conventional X-ray of the hand and fingers, no information can be obtained
about the volumetric density, microarchitecture, bone quality or volumetric erosion size.
Applying Dual-energy Xray absorptiometry (DXA) of peripheral joints, does also not provide
information about the volumetric bone density and no accurate difference can be obtained
regarding cortical or trabecular density parameters. Magnetic Resonance Imaging (MRI) as an
outcome measure in RA enables good the detection and partly quantification of erosions,
however no information about bone density can be quantified. HR-pQCT (high resolution
peripheral quantitative computed tomography) imaging allows in detail (82 micrometer
isotropic voxelsize) evaluation of density, microstructure parameters as well as
quantification of erosions in peripheral joints. Furthermore, HR-pQCT data allows the
biomechanical analysis of the bone and therefore statements on the bone quality can be made.
Modulating inhibitors targeting the Janus Kinase (JAK) - Signal Transducer and Activator of
Transcription (STAT) pathway, effect pro-inflammatory cytokines and have been approved for
therapy in RA patients. Analysis of the inhibition of the JAK-STAT pathway in rheumatoid
arthritis synovium showed decreased phosphorylation of STAT1. Also pro-inflammatory
activation of STAT1 and downstream targets were inhibited by JAK inhibition. More
interesting, STAT1-/- mice have higher bone density due to Runx2 activation but are otherwise
are indistinguishable from wildtype mice . Furthermore, inhibition of STAT1 accelerates bone
repair after trauma, a similar process in our observation in rheumatoid arthritis joints. On
the other hand, JAK1 deficient mice showed reduced body mass peri-natal which has been
speculated to indicate bone growth delays. Focusing on bone loss, JAK inhibition
(tofacitinib) suppressed osteoclast mediated bone destruction via reduction of T cell derived
RANKL. In vitro we observed that osteoclast (OC) differentiation was not influenced by JAK
inhibition in regard to OC numbers and transcription factor expression. Interestingly, in
osteoblast cultures, JAK inhibition induced Runx2, Col1a and Osterix. In co-culture assays
with osteoblasts and OC precursors JAK inhibition led to decreased OC differentiation.Thus
JAK inhibition mediated OC function is not only influenced by T cell but also osteoblast
derived RANKL and therefore interferes in the balance of bone turnover by activating
osteoblasts.Using HR-pQCT measurements of fingers of RA patients treated with tofacitinib in
a small sample size we detected an astonishing gain of volumetric bone mineral density (mg
Hydroxylapatite/mm³). Furthermore, we noticed a decrease of the intra-articular cortical
porosity and a positive change of erosion size. In these cases, volumetric bone density in
metacarpal joints improved up to 20 %. In our experience, regarding other immunosuppressive
medication for example anti-TNF Inhibition, no comparable effect was observed.
The longitudinal setup of this mode of action study is used to determine the effect of
baricitinib on the change of the volumetric bone mineral density in RA patients with
pathologic vBMD measured by HR-pQCT technique over 52 weeks.