SATISFY-JP, a phase II multicenter open-label study on Satralizumab, an anti-IL-6 receptor antibody, use for the treatment of pulmonary arterial hypertension in patients with an immune-responsive-phenotype: Study protocol.

Pulmonary arterial hypertension (PAH), an intractable disease with a poor prognosis, is commonly treated using pulmonary vasodilators modulating the endothelin, cGMP, and prostacyclin pathway. Since the 2010s, drugs for treating pulmonary hypertension based on mechanisms other than pulmonary vasodilation have been actively developed. However, precision medicine is based on tailoring disease treatment to particular phenotypes by molecular-targeted drugs. Since interleukin-6 (IL-6) is involved in the development of PAH in animal models, and some patients with PAH have elevated IL-6 levels, the cytokine is expected to obtain potentials for therapeutic targeting. Accordingly, we identified a phenotype with elevated cytokine activity of the IL-6 family in the PAH population by combining case data extracted from the Japan Pulmonary Hypertension Registry with a comprehensive analysis of 48 cytokines using artificial intelligence clustering techniques. Including an IL-6 threshold ≥2.73 pg/mL as inclusion criteria for reducing the risk of insufficient efficacy, an investigator-initiated clinical study using satralizumab, a recycling anti-IL6 receptor monoclonal antibody, for patients with an immune-responsive phenotype is underway. This study is intended to test whether use of patient biomarker profile can identify a phenotype responsive to anti-IL6 therapy.