Highlights of Dual-Energy Computed Tomography Findings from MIRROR RCT

A recent study published in Joint Bone Spine looked at the use of dual-energy CT (DECT) imaging to visualize and quantify monosodium-urate (MSU) crystal deposits in patients undergoing treatment for uncontrolled gout. Dual-energy CT imaging allows clinicians to see and quantify monosodium urate crystal deposits. The patients in this study specifically had urate-lowering therapy with pegloticase. Often, this patient population is recommended to undergo concomitant methotrexate therapy to enhance the urate-lowering results and reduce infusion reaction risks.
 
A previous, small, open-label trial demonstrated rapid depletion of monosodium urate deposits and subsequent bone-erosion remodeling in 2 cases when using this treatment combination. This study then aimed to confirm these findings in a larger cohort of patients from a randomized controlled trial (RCT) and investigate the impact of treatment duration.
 
In the trial, patients received either pegloticase plus methotrexate or pegloticase plus placebo. DECT imaging performed at various intervals assessed monosodium urate crystal volume (V_MSU) and bone erosion remodeling. Patients with paired baseline and Week 52 images were included in the analysis, excluding regions with minimal monosodium urate crystal volume to reduce artifacts.
 
Results showed that patients receiving pegloticase with or without methotrexate experienced a significant decrease in V_MSU over the treatment period, with faster depletion observed during pegloticase therapy. Bone-erosion remodeling was evident in a majority of evaluated erosions, including size decrease, recortication, and new bone formation.
 
Notably, patients who discontinued pegloticase therapy but maintained low (less than 6 mg/dL) serum urate levels with oral urate-lowering therapy (ULT) showed a slowdown or halt in V_MSU reduction, highlighting the importance of continued treatment for monosodium urate crystal depletion.
 
In conclusion, the study demonstrates rapid monosodium urate depletion with pegloticase therapy, accompanied by bone remodeling within one year of treatment. The findings emphasize the importance of sustained treatment to maintain therapeutic benefits in patients with uncontrolled gout.
 
Clinical trial registration: NCT03994731
 
Reference
1.     Dalbeth N, Botson J, Saag K, Kumar A, Padnick-Silver L, LaMoreaux B, Becce F. Examination of monosodium urate crystal depletion and bone erosion remodeling during pegloticase treatment in patients with uncontrolled gout: exploratory dual-energy computed tomography findings from MIRROR RCT. Joint Bone Spine. 2024 Mar 4:105715. doi: 10.1016/j.jbspin.2024.105715. Epub ahead of print. PMID: 38447697.