title: Age and Bone Marrow Cellularity are Associated with Response to Eltrombopag in Japanese Adult Immune Thrombocytopenia Patients: A Retrospective Single-Center Study.
abstract: In the present retrospective single-center study, we examined the efficacy and safety of eltrombopag, a thrombopoietin (TPO) -receptor agonist (TPO-RA), and found clinical factors associated with its efficacy in Japanese patients with chronic immune thrombocytopenia (ITP). According to the definition of a response, which is to attain a platelet count of more than 50,000/μL at least once during eltrombopag treatment, 42 enrolled patients were divided into two groups: responders (29 patients, 69%) and non-responders (13 patients, 31%). In analyses of the clinical and laboratory data of these two groups, we extracted two factors that are significantly associated with a better response to eltrombopag, which have not been recognized previously, namely, (1) an older age of patients at eltrombopag initiation (≥ 70 years old) and (2) normal or decreased cellularity of iliac bone marrow (BM) biopsy at diagnosis. The significance of patient age contradicts previous findings from studies in which the Caucasian population was the major focus. However, factors such as changes of pharmacokinetics might modulate the effects of eltrombopag in older patients in Japan because East Asians show higher bioavailability of eltrombopag by as-yet-unknown mechanisms. BM cellularity in ITP may represent an impairment and/or lower responsiveness of pluripotent hematopoietic stem cells, not limited to the megakaryocyte (MgK) -platelet axis, to endogenous TPO, because recent evidence shows that TPO-RA can successfully restore hematopoiesis in aplastic anemia. These results should be useful for the therapeutic use of TPO-RA for ITP and also related thrombocytopenia in Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Uto
authors.forename: Shun
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Nana
authors.initials: N
authors.lastname: Arai
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kabasawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsukamoto
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ariizumi
authors.forename: Norimichi
authors.initials: N
authors.lastname: Hattori
authors.forename: Bungo
authors.initials: B
authors.lastname: Saito
authors.forename: Kouji
authors.initials: K
authors.lastname: Yanagisawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Harada
authors.forename: Hiraku
authors.initials: H
authors.lastname: Mori
authors.forename: Eisuke
authors.initials: E
authors.lastname: Shiozawa
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nakamaki
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001565:Benzoates / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001854:Bone Marrow Cells; D005260:Female; D006412:Hematopoietic Stem Cells; D006801:Humans; D006834:Hydrazines / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D039904:Pluripotent Stem Cells; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000188:drug therapy*; D011720:Pyrazoles / Q000008:administration & dosage* / Q000493:pharmacokinetics; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001565:Benzoates; D006834:Hydrazines; D011720:Pyrazoles; C520809:eltrombopag