Fedratinib, sold under the brand name Inrebic, is an anti-cancer medication used to treat myeloproliferative diseases including myelofibrosis. It is used in the form of fedratinib hydrochloride capsules that are taken by mouth. It is a semi-selective inhibitor of Janus kinase 2 (JAK-2). It was approved by the FDA on 16 August 2019.Myelofibrosis is a myeloid cancer associated with anemia, splenomegaly, and constitutional symptoms. Patients with myelofibrosis frequently harbor mutations which activate the JAK-STAT signaling pathway and which are sensitive to fedratinib. Phase I trial results focused on safety and efficacy of fedratinib in patients with high- or intermediate-risk primary or post–polycythemia vera/essential thrombocythemia myelofibrosis have been published in 2011. Medical uses
In the United States, fedratinib is indicated for the treatment of adults with intermediate-2 or high-risk primary or secondary (following polycythemia vera or essential thrombocythemia) myelofibrosis.In the European Union, fedratinib is indicated for the treatment of disease-related splenomegaly or symptoms in adults with primary myelofibrosis, following polycythaemia vera or essential thrombocythaemia, who are Janus kinase (JAK) inhibitor naïve or have been treated with ruxolitinib. Pharmacology
Mechanism of action
Fedratinib acts as a competitive inhibitor of protein kinase JAK-2 with IC50=6 nM; related kinases FLT3 and RET are also sensitive, with IC50=25 nM and IC50=17 nM, respectively. Significantly less activity was observed against other tyrosine kinases including JAK3 (IC50=169 nM). In treated cells the inhibitor blocks downstream cellular signalling (JAK-STAT) leading to suppression of proliferation and induction of apoptosis. History
Fedratinib was originally discovered at TargeGen. In 2010, Sanofi-Aventis acquired TargeGen and continued development of fedratinib until 2013.
Tioguanine, also known as thioguanine or 6-thioguanine (6-TG) is a medication used to treat acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), and chronic myeloid leukemia (CML). Long-term use is not recommended. It is given by mouth.Common side effects include bone marrow suppression, liver problems and inflammation of the mouth. It is recommended that liver enzymes be checked weekly when on the medication. People with a genetic deficiency in thiopurine S-methyltransferase are at higher risk of side effects. Avoiding pregnancy when on the medication is recommended for both males and females. Tioguanine is in the antimetabolite family of medications. It is a purine analogue of guanine and works by disrupting DNA and RNA.Tioguanine was developed between 1949 and 1951. It is on the World Health Organizations List of Essential Medicines. Medical uses
Acute leukemias in both adults and children
Chronic myelogenous leukemia
Inflammatory bowel disease, especially ulcerative colitis
Psoriasis

Side effects
Leukopenia and neutropenia
Thrombocytopenia
Anemia
Anorexia
Nausea and vomiting
Hepatotoxicity: this manifests as:

Hepatic veno-occlusive disease
The major concern that has inhibited the use of thioguanine has been veno-occlusive disease (VOD) and its histological precursor nodular regenerative hyperplasia (NRH). The incidence of NRH with thioguanine was reported  as between 33 and 76%. The risk of ensuing VOD is serious and frequently irreversible so this side effect has been a major concern. However, recent evidence using an animal model for thioguanine-induced NRH/VOD has shown that, contrary to previous assumptions, NRH/VOD is dose dependent and the mechanism for this has been demonstrated.