The United States Food and Drug Administration (FDA) has approved United States-based Celgene's Inrebic (fedratinib) intended to treat adult patients with intermediate-two or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis, it was reported yesterday.

The product is an oral kinase inhibitor with activity against wild type and mutationally activated Janus Associated Kinase 2 (JAK2) and FMS-like tyrosine kinase 3 (FLT3). It is a JAK2-selective inhibitor with higher potency for JAK2 over family members JAK1, JAK3 and TYK2. It decreased phosphorylation of signal transducer and activator of transcription (STAT3/5) proteins, inhibited cell proliferation and induced apoptotic cell death in cell models expressing mutationally active JAK2 or FLT3.

The product's development programme covers multiple studies, including Jakarta and Jakarta 2. The trials hired 608 patients, receiving more than one dose ranging from 30mg to 800mg, of whom 459 had myelofibrosis and around 97% treated with ruxolitinib. The phase three multicentre, randomised, double-blind and placebo-controlled trial evaluated the efficacy of once-daily oral doses of Inrebic compared with placebo in patients with intermediate-two or high-risk primary or secondary myelofibrosis and a platelet count of up to 50 x 10/9/L who were earlier untreated with a JAK inhibitor. The company said that the primary endpoint was spleen response rate.