Chronic recurrent multifocal osteomyelitis (CRMO) is a rare auto-inflammatory bone disease that primarily affects children and/or adolescents at a median age of 10 years. Until now, there is no consensus regarding the treatment of CRMO. Non-steroidal anti-inflammatory drugs (NSAIDs) are considered the first line of therapy with remission in approximately 30% of cases. If unsuccessful, several treatments are tried in addition to NSAIDs, including bisphosphonates and anti-TNFs.
The effectiveness of bisphosphonates (including zoledronate) has been reported in clinical cases and/or retrospective series. They are said to be particularly effective in multifocal forms, mandibular and/or vertebral involvement, but no controlled trials have been conducted. Bisphosphonates have even been proposed as first-line therapy in spinal involvement. The only prospective study, is a phase II trial currently underway in Denmark to study the efficacy of zoledronate (NCT02594878) versus placebo in SAPHO (acronym, standing for Synovitis - Acne - Pustulosis - Hyperostosis - Osteitis) patients considered to be a very similar form of CRMO occurring in adults.
In this context, this study proposes evaluate the efficacy of zoledronate compared to placebo in reducing pain at week 12 in children aged ≥4 and \<17 years with NSAID-resistant CRMO. Zoledronate will be administered in three escalating doses: 0.025 mg/kg at baseline (W0), 0.05 mg/kg at week 12 (W12), and 0.05 mg/kg at week 24 (W24). In addition to pain reduction, improvements in MRI findings will be observed, biological markers of inflammation, and quality of life in the zoledronate group. Although subjective, pain reduction remains the most widely used criterion in clinical practice to assess therapeutic efficacy. Zoledronate efficacy will therefore be assessed by the change in standardized pain score (0-10 scale) from baseline to week 12 as the primary endpoint, with additional pain assessments at weeks 4, 24, and 36 as secondary endpoints.