Sustained Interferon Signature Suppression With Anifrolumab in a Patient With STING-Associated Vasculopathy with Onset in Infancy Refractory to JAK Inhibitor and Dazukibart Therapy

Objective: The objective was to report the safety and efficacy of an anti-IFNAR1 antibody (anifrolumab) in a patient with STING-associated vasculopathy with onset in infancy (SAVI) who presented with vasculitic ulcers and systemic inflammation refractory to JAK inhibition (JAKi) and to the interferon-β–neutralizing monoclonal antibody dazukibart. Methods: A patient with SAVI and a de novo STING1 p.(Asn154Ser) mutation, a known pathogenic variant, and uncontrolled disease received 21 doses of dazukibart under a compassionate use investigational new drug protocol, which was followed by treatment with the anti-IFNAR1 antibody anifrolumab. Clinical and laboratory parameters, including wound healing, whole-blood type I interferon (IFN I) signature, and safety markers were closely monitored throughout both treatment periods. Results: Despite initial reductions in C-reactive protein levels and IFN I scores following dazukibart administration, the patient experienced rebound inflammation and recurrent vasculitic lesions. Dazukibart dose adjustments failed to sustainably control IFN I signaling. Subsequent combination therapy of baricitinib and tocilizumab proved partially effective. Treatment with anifrolumab, an IFNAR1 blocker, in conjunction with tocilizumab led to sustained suppression of IFN I scores, allowed discontinuation of JAKi, and resulted in significant improvement in vasculitic wounds. Conclusion: This case underscores the challenges in treating patients with SAVI and highlights the utility of IFN I scores as a theragnostic biomarker. Although high-dose JAKi and dazukibart failed to achieve sustained control of IFN I signaling, treatment with anifrolumab durably suppressed IFN scores and demonstrated promising efficacy, which allows for the investigation of the role of IFN I signaling in the disease pathogenesis of SAVI and other interferonopathies in future clinical trials.