{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T19:58:58Z","timestamp":1785441538473,"version":"3.56.0"},"reference-count":20,"publisher":"Springer Science and Business Media LLC","license":[{"start":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T00:00:00Z","timestamp":1785369600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T00:00:00Z","timestamp":1785369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/100016288","name":"Kissei Pharmaceutical Co., Ltd.","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100016288","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Int J Hematol"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Fostamatinib was approved in Japan in December 2022 for primary immune thrombocytopenia (ITP). Given the limited clinical trial data, post-marketing surveillance (PMS) was conducted in Japan to collect safety and effectiveness data for fostamatinib. This interim analysis of PMS collected data between April 2023 and April 2025. Most of the 489 patients in the safety analysis set had received\u2009\u2265\u20093 treatment lines. Approximately 70% used fostamatinib with glucocorticoids and\/or a thrombopoietin receptor agonist. Adverse drug reactions (ADRs) were reported in 49.5% (serious ADRs in 8.6%). The most common ADRs were diarrhoea (20.0%), hypertension (15.7%), hepatic function abnormal (9.6%), liver disorders (4.9%), and neutrophil count decreased (4.1%). Safety analysis revealed no major differences in the frequency of ADRs, including those of special interest, by combination treatment(s). Median platelet count increased at 2 weeks of treatment and remained above 50,000\/\u03bcL thereafter, regardless of the ITP treatment combination. Further, complete response (platelet count\u2009\u2265\u2009100,000\/\u03bcL) was observed in 135 of 309 patients at 3 months and 128 of 241 patients at 6 months under continuous fostamatinib use. The results of this real-world PMS revealed no new safety concerns and support the effectiveness of fostamatinib in patients with primary ITP.<\/jats:p>","DOI":"10.1007\/s12185-026-04259-2","type":"journal-article","created":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T06:27:24Z","timestamp":1785392844000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Post-marketing surveillance of fostamatinib for primary immune thrombocytopenia in Japan: interim analysis"],"prefix":"10.1007","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8352-6136","authenticated-orcid":false,"given":"Masataka","family":"Kuwana","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shoichi","family":"Yoshioka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maki","family":"Wakabayashi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masaya","family":"Marumo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masanari","family":"Furuya","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mari","family":"Yato","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"So","family":"Saotome","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kazunori","family":"Abe","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,7,30]]},"reference":[{"issue":"2","key":"4259_CR1","doi-asserted-by":"publisher","DOI":"10.3390\/jcm6020016","volume":"6","author":"A Zufferey","year":"2017","unstructured":"Zufferey A, Kapur R, Semple JW. Pathogenesis and therapeutic mechanisms in immune thrombocytopenia (ITP). J Clin Med. 2017;6(2):16.","journal-title":"J Clin Med"},{"key":"4259_CR2","doi-asserted-by":"publisher","first-page":"S27","DOI":"10.1053\/j.seminhematol.2016.04.009","volume":"53","author":"M Kuwana","year":"2016","unstructured":"Kuwana M. What do we learn from immunomodulation in patients with immune thrombocytopenia? Semin Hematol. 2016;53:S27\u201330.","journal-title":"Semin Hematol"},{"issue":"12","key":"4259_CR3","doi-asserted-by":"publisher","DOI":"10.3390\/cells10123386","volume":"10","author":"S Sun","year":"2021","unstructured":"Sun S, Urbanus RT, Ten Cate H, de Groot PG, de Laat B, Heemskerk JWM, et al. Platelet activation mechanisms and consequences of immune thrombocytopenia. Cells. 2021;10(12):3386.","journal-title":"Cells"},{"issue":"3","key":"4259_CR4","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1007\/s12185-011-0791-1","volume":"93","author":"Y Kurata","year":"2011","unstructured":"Kurata Y, Fujimura K, Kuwana M, Tomiyama Y, Murata M. Epidemiology of primary immune thrombocytopenia in children and adults in Japan: a population-based study and literature review. Int J Hematol. 2011;93(3):329\u201335.","journal-title":"Int J Hematol"},{"key":"4259_CR5","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1111\/j.1600-0609.2008.01206.x","volume":"71","author":"M Michel","year":"2009","unstructured":"Michel M. Immune thrombocytopenic purpura: epidemiology and implications for patients. Eur J Haematol Suppl. 2009;71:3\u20137.","journal-title":"Eur J Haematol Suppl"},{"issue":"3","key":"4259_CR6","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1007\/s12185-019-02790-z","volume":"111","author":"H Kashiwagi","year":"2019","unstructured":"Kashiwagi H, Kuwana M, Hato T, Takafuta T, Fujimura K, Kurata Y, et al. Reference guide for management of adult immune thrombocytopenia in Japan: 2019 revision. Int J Hematol. 2019;111(3):329\u201351.","journal-title":"Int J Hematol"},{"issue":"23","key":"4259_CR7","doi-asserted-by":"publisher","first-page":"3829","DOI":"10.1182\/bloodadvances.2019000966","volume":"3","author":"C Neunert","year":"2019","unstructured":"Neunert C, Terrell DR, Arnold DM, Buchanan G, Cines DB, Cooper N, et al. American society of hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019;3(23):3829\u201366.","journal-title":"Blood Adv"},{"issue":"6","key":"4259_CR8","doi-asserted-by":"publisher","first-page":"1112","DOI":"10.3324\/haematol.2018.212845","volume":"104","author":"G Waleed","year":"2019","unstructured":"Waleed G, Nichola C, Francesco R, Bertrand G, James BB. Thrombopoietin receptor agonists: ten years later. Haematologica. 2019;104(6):1112\u201323.","journal-title":"Haematologica"},{"key":"4259_CR9","unstructured":"Kissei Pharmaceutical Co., Ltd. Marketing Authorization Approval in Japan for TAVALISSE\u00ae Tab. 100mg and 150mg, an Oral Spleen Tyrosine Kinase Inhibitor. Available at: https:\/\/www.kissei.co.jp\/e_contents\/news\/2022\/20221223-4582.html. Accessed 23 July 2025."},{"issue":"2","key":"4259_CR10","doi-asserted-by":"publisher","first-page":"E55","DOI":"10.1002\/ajh.27176","volume":"99","author":"M Kuwana","year":"2024","unstructured":"Kuwana M, Ito T, Kowata S, Hatta Y, Fujimaki K, Naito K, et al. Long-term treatment with fostamatinib in Japanese patients with primary immune thrombocytopenia: an open-label extension study following a phase 3 placebo-controlled, double-blind, parallel-group study. Am J Hematol. 2024;99(2):E55\u20139.","journal-title":"Am J Hematol"},{"issue":"6","key":"4259_CR11","doi-asserted-by":"publisher","first-page":"802","DOI":"10.1111\/bjh.18582","volume":"200","author":"M Kuwana","year":"2023","unstructured":"Kuwana M, Ito T, Kowata S, Hatta Y, Fujimaki K, Naito K, et al. Fostamatinib for the treatment of Japanese patients with primary immune thrombocytopenia: a phase 3, placebo-controlled, double-blind, parallel-group study. Br J Haematol. 2023;200(6):802\u201311.","journal-title":"Br J Haematol"},{"issue":"4","key":"4259_CR12","doi-asserted-by":"publisher","first-page":"1551","DOI":"10.1111\/bjh.19602","volume":"205","author":"ME Mingot-Castellano","year":"2024","unstructured":"Mingot-Castellano ME, Bastida JM, Ghanima W, Ruiz Sainz E, Nu\u00f1ez Vazquez R, Pedrote Amador B, et al. Avatrombopag plus fostamatinib combination as treatment in patients with multirefractory immune thrombocytopenia. Br J Haematol. 2024;205(4):1551\u20135.","journal-title":"Br J Haematol"},{"issue":"5","key":"4259_CR13","doi-asserted-by":"publisher","first-page":"2129","DOI":"10.1111\/bjh.19450","volume":"204","author":"M Passucci","year":"2024","unstructured":"Passucci M, Lagan\u00e0 A, Donzelli L, Masucci C, Genoese A, Chistolini A, et al. Fostamatinib combined with TPO-RAs or steroids as a bridge to monotherapy or as time-limited continuous treatment in relapsed chronic ITP: a single-centre case series. Br J Haematol. 2024;204(5):2129\u201332.","journal-title":"Br J Haematol"},{"issue":"3","key":"4259_CR14","doi-asserted-by":"publisher","first-page":"356","DOI":"10.1007\/s12185-025-03924-2","volume":"121","author":"M Kuwana","year":"2025","unstructured":"Kuwana M, Tomiyama Y. Long-term safety and efficacy of fostamatinib in Japanese patients with primary immune thrombocytopenia. Int J Hematol. 2025;121(3):356\u201362.","journal-title":"Int J Hematol"},{"issue":"5","key":"4259_CR15","doi-asserted-by":"publisher","first-page":"546","DOI":"10.1002\/ajh.25444","volume":"94","author":"JB Bussel","year":"2019","unstructured":"Bussel JB, Arnold DM, Boxer MA, Cooper N, Mayer J, Zayed H, et al. Long-term fostamatinib treatment of adults with immune thrombocytopenia during the phase 3 clinical trial program. Am J Hematol. 2019;94(5):546\u201353.","journal-title":"Am J Hematol"},{"issue":"6","key":"4259_CR16","doi-asserted-by":"publisher","first-page":"665","DOI":"10.1007\/s12185-024-03847-4","volume":"120","author":"N Obara","year":"2024","unstructured":"Obara N, Hatanaka S, Tsuji Y, Higashi K. Long-term safety and effectiveness of romiplostim for chronic idiopathic thrombocytopenic purpura in real-world settings. Int J Hematol. 2024;120(6):665\u201374.","journal-title":"Int J Hematol"},{"key":"4259_CR17","unstructured":"Akatsu S, Kawaguchi M, Zhang F, Wong T-F. Real world safety and effectiveness of eltrombopag olamine (Revolade\u24c7 tablet) in patients with chronic idiopathic thrombocytopenic purpura: the final report of drug use-results survey. Shinryo to Shinyaku (Med Cons New-Remed). 2021;58(7):505\u201320."},{"issue":"7","key":"4259_CR18","doi-asserted-by":"publisher","first-page":"921","DOI":"10.1002\/ajh.25125","volume":"93","author":"J Bussel","year":"2018","unstructured":"Bussel J, Arnold DM, Grossbard E, Mayer J, Treli\u0144ski J, Homenda W, et al. Fostamatinib for the treatment of adult persistent and chronic immune thrombocytopenia: results of two phase 3, randomized, placebo-controlled trials. Am J Hematol. 2018;93(7):921\u201330.","journal-title":"Am J Hematol"},{"issue":"4","key":"4259_CR19","doi-asserted-by":"publisher","first-page":"736","DOI":"10.1002\/ajh.70194","volume":"101","author":"G Moulis","year":"2026","unstructured":"Moulis G, Mah\u00e9vas M, Viallard J-F, Ch\u00e8ze S, Terriou L, Audia S, et al. Real-world effectiveness and safety of fostamatinib in difficult-to-treat immune thrombocytopenia patients. A prospective, multicenter registry in France. Am J Hematol. 2026;101(4):736\u201345.","journal-title":"Am J Hematol"},{"issue":"6","key":"4259_CR20","doi-asserted-by":"publisher","first-page":"646","DOI":"10.1182\/blood.2024024250","volume":"144","author":"TJ Gonz\u00e1lez-L\u00f3pez","year":"2024","unstructured":"Gonz\u00e1lez-L\u00f3pez TJ, Bermejo-Vega N, Cardesa-Cabrera R, Mart\u00ednez-Robles V, Aguilar-Monserrate G, P\u00e9rez-Segura G, et al. Fostamatinib effectiveness and safety for immune thrombocytopenia in clinical practice. Blood. 2024;144(6):646\u201356.","journal-title":"Blood"}],"container-title":["International Journal of Hematology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s12185-026-04259-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1007\/s12185-026-04259-2","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s12185-026-04259-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T19:05:27Z","timestamp":1785438327000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1007\/s12185-026-04259-2"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,30]]},"references-count":20,"alternative-id":["4259"],"URL":"https:\/\/doi.org\/10.1007\/s12185-026-04259-2","relation":{},"ISSN":["0925-5710","1865-3774"],"issn-type":[{"value":"0925-5710","type":"print"},{"value":"1865-3774","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,30]]},"assertion":[{"value":"5 March 2026","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"17 July 2026","order":2,"name":"revised","label":"Revised","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"20 July 2026","order":3,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"30 July 2026","order":4,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"Masataka Kuwana receives honoraria from Kissei Pharmaceutical Co., Ltd. Shoichi Yoshioka, Maki Wakabayashi, Masaya Marumo, Masanari Furuya, Mari Yato, So Saotome and Kazunori Abe are employees of Kissei Pharmaceutical Co., Ltd.","order":1,"name":"Ethics","label":"Conflict of interest","group":{"name":"EthicsHeading","label":"Declarations"}}]}}