Preliminary results demonstrate patients with chronic idiopathic thrombocytopenic purpura increased and maintained platelet counts at greater than or equal to 50,000/microliters with extended treatment
ATLANTA, Dec. 10 /PRNewswire-USNewswire/ -- GlaxoSmithKline today announced data on the long-term safety and efficacy of its investigational drug PROMACTA(TM) (eltrombopag) for the treatment of chronic idiopathic thrombocytopenic purpura (ITP).(1) These preliminary results from the EXTEND (Eltrombopag eXTENded Dosing) study showed that of the patients with a baseline platelet count of less than 30,000/microliters, 73% achieved a platelet count of greater than or equal to 50,000/microliters. The average treatment period for all patients, from this ongoing treatment study, has lasted almost 22 weeks (five months) so far. These results suggest that PROMACTA sustains increased platelet counts during long-term treatment.(1) This research was presented at the 49th Annual Meeting of the American Society of Hematology, December 8-11 2007 in Atlanta, GA.
PROMACTA is an investigational compound that has not received regulatory approval in any market for any indication at this time.
PROMACTA was generally well tolerated in this study. Of the 94 patients who received at least one dose of PROMACTA, 83% reported at least one adverse event (AE), 32% reported a drug-related AE and 13% reported a serious AE (SAE). Most AEs were mild in severity with the most common being headache (20%).(1)
Chronic ITP is a disorder characterized by low levels of platelets in the blood, with patients suffering from excessive bruising and bleeding and in some cases having serious hemorrhages that can be fatal.(2,3,4) An estimated 200,000 individuals are diagnosed with ITP in the U.S.(5) and a similar number in Europe. PROMACTA is an investigational oral, non-peptide, platelet growth factor that induces the proliferation and differentiation of cells in the bone marrow to produce platelets.(6,7)
"These long-term results on safety and efficacy are encouraging and suggest that PROMACTA, once approved, may provide physicians with a new treatment option to raise and maintain patients' platelet levels and alleviate their ITP symptoms," said James B. Bussel, MD, director of the Platelet Disorders Center, Children's Blood Foundation Division at New York-Presbyterian Hospital/Weill Cornell Medical Center, and principal investigator for this trial.
The EXTEND study
EXTEND is a study designed to assess the long-term safety and efficacy of PROMACTA as an oral treatment for increasing platelets in patients with chronic ITP. EXTEND is an open-label study for patients who had participated in previous PROMACTA trials and were eligible to receive PROMACTA.(8)
Chronic ITP patients were administered a starting dose of 50 mg/day (which can be increased to 75 mg/day at any time after 3 weeks) in order to reach a platelet count of greater than or equal to 50,000/microliters or greater than or equal to 100,000/microliters if patients were receiving concomitant ITP medication (stage 1). Then, concomitant ITP medications, if taken at study entry, were tapered to a minimal dose or discontinued entirely (stage 2), whilst maintaining a platelet count of greater than or equal to 50,000/microliters. PROMACTA was then titrated to a minimal effective dose (25-75 mg/day) required to maintain platelet counts of 50,000/microliters-200,000/microliters (stage 3). PROMACTA is continued for as long as patients continue to benefit and platelets remain greater than or equal to 50,000/microliters (stage 4). Bleeding incidences and severity were assessed using the WHO bleeding scale (Grade 0-4).
At the time of this analysis PROMACTA had been administered to 94 patients. Evaluable subjects (n=89) had a median treatment duration of 151 days, with the longest treatment duration at 333 days. At baseline, 63% of patients had evidence of bleeding (World Health Organization [WHO] Grade 1-4) and 44% had platelet counts less than or equal to 15,000/microliters. Seventeen patients had entered stage two of the study. Median platelet count was 143,500 microliters. Twenty-seven patients proceeded to long-term treatment with PROMACTA (maintenance stage), achieving median platelet counts of 104,000/microliters with only one patient (4%) showing evidence of bleeding (WHO Grade 2-4).
PROMACTA is an oral, non-peptide, thrombopoietin receptor agonist that has been shown in pre-clinical research and clinical trials to stimulate the proliferation and differentiation of megakaryocytes, the bone marrow cells that give rise to blood platelets, and thus can be considered a platelet growth factor.(9) The efficacy and safety profile will be further examined in ongoing clinical trials. PROMACTA was discovered as a result of research collaboration between GlaxoSmithKline and Ligand Pharmaceuticals. It is being developed by GlaxoSmithKline.
GlaxoSmithKline is one of the world's leading research-based pharmaceutical and healthcare companies. GlaxoSmithKline is committed to improving the quality of human life by enabling people to do more, feel better and live longer. For company information visit http://www.gsk.com.
Notes to Editors
PROMACTA(TM) is the registered trade mark of the GlaxoSmithKline group of companies.
PROMACTA(TM) is the proposed registered trademark to be used in the United States.
The study was financially supported by GlaxoSmithKline. Dr. Bussel is an Advisory Board Member for GlaxoSmithKline and has received research grant support, lecture fees, and consulting fees from GlaxoSmithKline and reports equity ownership in GlaxoSmithKline.
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(1) Bussel, JB., Cheng, G., et al. Long-term safety and efficacy of oral eltrombopag for the treatment of subjects with idiopathic thrombocytopenic purpura (ITP): preliminary data from the EXTEND study. Blood. 2007; 110 (11). Published online, Nov 2007.
(2) McMillan, R., Bussel, JB., et al. Self-reported health-related quality of life in adults with chronic immune thrombocytopenic purpura. Am Hematol. Published online, 23 Aug 2007.
(3) Cines, DB., McMillan, R. Management of adult idiopathic thrombocytopenic purpura. Annu Rev Med. 2005;56: 425-442.
(4) Idiopathic Thrombocytopenic Purpura (ITP) factsheet. Great Ormond Street Hospital for Children NHS Trust. August 2004.
(5) About ITP. Platelet Disorder Support Association (PDSA). Available at http://www.pdsa.org/itp-information/index.html . Accessed 23 November 2007.
(6) Jenkins J, Williams D, Deng Y, et al. Phase I clinical study of eltrombopag, an oral, nonpeptide thrombopoietin receptor agonist. Blood. 2007: 109:4739-4741.
(7) Erickson-Miller, C., Delorme, E., et al Biological Activity and Selectivity for TPO Receptor of the Orally Bioavailable, Small Molecule TPO receptor Agonist, SB-497115. Blood. 2004; 104:796a.
(8) Study TRA105325 protocol.
(9) Bussel, J., Cheng, G., et al. Analysis of Bleeding in Patients with Immune Thrombocytopenic Purpura (ITP): A Randomized, Double-Blind, Placebo-Controlled Trial of Eltrombopag, an Oral Platelet Growth Factor. Blood. 2006; 108: 475.
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