{"entity":{"id":"pt-1","kind":"trial","name":"PT-1 (Primary Thrombocythaemia 1)","aka":[],"tldr":"PT-1 is the trial that made hydroxyurea the first-line drug in high-risk ET: anagrelide gave more arterial clots, more serious bleeding and more progression to myelofibrosis.","summary":"PT-1 randomised 809 patients with high-risk essential thrombocythaemia to hydroxyurea or anagrelide, both with low-dose aspirin. After a median of 39 months the composite primary endpoint of arterial or venous thrombosis, serious haemorrhage or death from a thrombotic or haemorrhagic cause was more frequent on anagrelide (odds ratio 1.57); anagrelide gave more arterial clots, serious bleeding and transformation to myelofibrosis, and fewer venous clots (Harrison and colleagues, New England Journal of Medicine 2005). Registered as ISRCTN72251782.","status":"positive","asOf":"2026-09-16","links":[{"label":"ISRCTN72251782","url":"https://www.isrctn.com/ISRCTN72251782"},{"label":"NEJM 2005","url":"https://www.nejm.org/doi/full/10.1056/NEJMoa043800"}],"tags":["essential-thrombocythaemia","mpn"],"related":[],"cancers":["essential-thrombocythaemia","myeloproliferative-neoplasms"],"sections":[],"technologies":[],"targets":[],"drugs":["hydroxyurea","anagrelide"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"notes":[],"phase":"3","setting":"High-risk essential thrombocythaemia: hydroxyurea plus aspirin versus anagrelide plus aspirin","sponsor":"Medical Research Council (UK)","result":"Composite of thrombosis, serious haemorrhage or vascular death more frequent with anagrelide (odds ratio 1.57); more arterial clots, bleeding and myelofibrosis on anagrelide.","yearReported":2005,"enrolled":809,"outcomes":[]},"route":"/trials/pt-1/","neighbours":{"cancer":[{"id":"essential-thrombocythaemia","kind":"cancer","name":"Essential thrombocythaemia (ET)","route":"/cancers/essential-thrombocythaemia/"},{"id":"myeloproliferative-neoplasms","kind":"cancer","name":"Myeloproliferative neoplasms (PV, ET, myelofibrosis)","route":"/cancers/myeloproliferative-neoplasms/"}],"drug":[{"id":"anagrelide","kind":"drug","name":"Anagrelide","route":"/drugs/anagrelide/"},{"id":"hydroxyurea","kind":"drug","name":"Hydroxyurea (hydroxycarbamide)","route":"/drugs/hydroxyurea/"}]}}