Intra-alveolar haemorrhage (IAH) is a rare and often severe disease in children. In IAH related to COPA syndrome, use of ruxolitinib results in an improvement of the disease. Ruxolitinib was proposed in 4 children referred to 2 tertiary centres in France for severe IAH and autoinflammatory features despite negative screening for COPA mutations. Two of them had ANCA auto antibodies. We retrospectively analysed the efficacy of ruxolitinib on the number of flares, steroids weaning, haemoglobin rate and growth. The number of flares could be reduced by 60 to 100% depending on the patient. Steroid therapy was reduced in 2 and discontinued in 2 patients. General course was favourable with a resumption of growth. The treatment was well tolerated and no significant adverse events occurred.

Figure 1 : IAH flares according to time. Number of flares before and after the introduction of ruxolitinib. X is the duration of follow-up for each patient since the introduction of ruxolitinib .

This first paediatric study investigated the efficacy of Jak inhibitors in the treatment of HIA without COPA mutations. Although the number of patients is small, our results are encouraging. Patients with IAH should be screening for interferon signature even when screening for mutations in COPA is negative. In patients with a patent autoinflammation, Ruxolitinib should be consider in case of failure of other treatments.