Romiplostim.
*Romiplostim is an Fc-peptide fusion protein (or 'peptibody') that stimulates megakaryopoiesis and thrombopoiesis by binding to, and activating, the thrombopoietin receptor. *Because it has no sequence homology to thrombopoietin, romiplostim theoretically avoids the risk of eliciting cross-reacting, neutralizing antibodies to thrombopoietin. *In well designed, 24-week, phase III trials, subcutaneous romiplostim was significantly more effective than placebo in achieving the primary endpoint of a protocol-defined durable platelet response in nonsplenectomized (61% vs 5%) or splenectomized (38% vs 0%) adults with chronic immune (idiopathic) thrombocytopenic purpura (ITP). *Romiplostim was also significantly more effective than placebo with regard to a number of secondary endpoints, including the proportions of patients with an overall (durable plus transient) platelet response or who required ITP rescue medications. The majority of romiplostim-treated patients receiving concurrent ITP drugs were able to reduce or discontinue these therapies. *Platelet response was maintained by most patients during longer-term treatment with romiplostim for up to 3 or 4 years in an open-label extension study. *Romiplostim was generally well tolerated. Almost all adverse events in the phase III studies were of mild-to-moderate intensity; most were unrelated to treatment. Longer-term treatment with romiplostim had an adverse event profile consistent with that observed in the phase III studies.
Frampton
James E
JE
Wolters Kluwer Health | Adis, Auckland, New Zealand. demail@adis.co.nz
Lyseng-Williamson
Katherine A
KA
D002352:Carrier Proteins / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D002908:Chronic Disease; D017326:Clinical Trials, Phase III as Topic; D006801:Humans; D055104:Infusions, Subcutaneous; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000188:drug therapy*; D011961:Receptors, Fc / Q000627:therapeutic use; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D013926:Thrombopoietin
D002352:Carrier Proteins; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; D013926:Thrombopoietin; C488777:romiplostim