Effectiveness and safety of neridronate in chronic nonbacterial osteomyelitis: insight from the CAMELOT registry

Background: Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory noninfectious disease of the bone that predominantly affects children and adolescents. Bisphosphonates (BPs) are used to treat of CNO with most clinical experience involving pamidronate. Neridronate (NER) is an amino BP with a chemical structure and potency close to pamidronate. Objectives: This study aims to evaluate the effectiveness and safety of NER in patients with CNO. Design: Monocentric retrospective cohort study. Methods: This is a retrospective cohort study conducted on patients included in the monocentric CAMELOT (Chronic non-bActerial osteoMyELitis: A mOnocentric regisTry) registry. Response to treatment was evaluated semiquantitatively based on clinical, laboratory, and radiological domains. Results: The cohort consisted of 27 subjects. Thirteen (48%) received NER alone. At baseline, patients receiving NER alone tended to have a higher rate of vertebral fractures than those treated with combination therapy (46% vs 29%; p = 0.4). The median number of peripheral lesions at magnetic resonance imaging was clearly lower in patients treated with NER alone (0 (interquartile range (IQR) 0–2) vs 2 (IQR 1–5); p = 0.01). An overall response (complete or partial) to NER was documented in all but one patient (96%). Six patients (22%) achieved a complete response in all the three domains, 83% of whom ( n = 5) received NER without any other concomitant treatments. Interestingly, using a Receiver Operating Characteristic-derived cutoff of 2 years from CNO diagnosis, all patients who achieved a complete response (100%) had received NER within the first 2 years from diagnosis, compared with 57% ( n = 12) of those who did not ( p = 0.07). No long-term NER complications were observed. Conclusion: Neridronate appears to be a safe and effective option for CNO, particularly in patients with recent-onset disease, spinal involvement, and fewer peripheral lesions. Early initiation may be associated with higher rates of complete response, though further studies are needed to confirm these findings.