Session: 631. Chronic Myeloid Leukemia: Biology and Pathophysiology, excluding Therapy: Poster I
Hematology Disease Topics & Pathways:
Diseases, CML, Myeloid Malignancies
Methods: Bone marrow samples were obtained from the patients with CML in chronic phase who were treated solely with TKIs at Keio University Hospital (Tokyo, Japan). This study was approved by the institutional ethical committee and informed consent was obtained from each patient. Both quantitative and qualitative PCR of BCR-ABL1 was performed using bone marrow mononuclear cells (BMMNCs). The proportion of CD25-positive cells in bone marrow hematopoietic stem/progenitor cell (HSPC; CD34+CD38-) fraction (%CD25+) was evaluated by flow cytometry. The response to TKIs at the time of analysis was determined according to as follows: complete cytogenetic remission (CCyR) defined as Philadelphia chromosome undetectable and quantitative PCR copy numbers >731 among BMMNCs; major molecular remission (MMR) as quantitative PCR copy numbers ≤731, and complete molecular remission (CMR) as undetectable BCR-ABL1 by quantitative and qualitative PCR.
Results: Bone marrow samples obtained from 109 patients were evaluated (median age, 52 years; male/female, 76/33). Analysis was performed prior to TKI exposure in 26 patients and under TKI therapy in 64 patients (imatinib, 22; dasatinib, 33; nilotinib, 9). Remaining 19 patients were treatment free because they were enrolled into a clinical trial of TKI discontinuation. At diagnosis (n=26), %CD25+ were significantly correlated with hemoglobin level and platelet count (Table). The %CD25+ was significantly lower in patients with post TKI exposure than those at diagnosis without TKIs (p<0.00001). In nine patients with available samples before and after TKI therapy, the %CD25+ at diagnosis was significantly higher than after TKI therapy (Mean 34.7%, SD 24.8% vs. Mean 4.96%, SD 4.17%, p<0.01, Fig.a). In addition, %CD25+ was significantly correlated with copy number of BCR/ABL1 (P<0.001, Fig.b).
Disclosures: Kasahara: Chugai: Research Funding. Sakurai: Bristol-Myers Squibb K.K.: Speakers Bureau. Kikuchi: Celgene: Speakers Bureau; Takeda: Speakers Bureau; Ono: Speakers Bureau. Shimizu: Bristol-Myers Squibb K.K: Honoraria. Mori: Astella Pharma: Honoraria; Kyowa Hakko Kirin: Honoraria; Novartis Pharma: Research Funding; MSD: Research Funding; MSD: Honoraria; Janssen: Honoraria; SHIONOGI: Honoraria; Taisho Toyama Pharmaceutical Co: Honoraria; Celgene: Honoraria; Ono: Honoraria; Eisai: Honoraria; Novartis Pharma: Honoraria; Shire Japan: Honoraria; CHUGAI: Honoraria; Asahi Kasei: Research Funding; Japan Blood Products Organization: Honoraria; Pfizer: Honoraria. Okamoto: Pfizer Inc.: Honoraria, Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Eisai Co.,Ltd.: Research Funding; Kyowa Hakko Kirin Co.: Research Funding; Bristol-Myers Squibb K.K.: Honoraria, Research Funding; Teijin Pharma Limited: Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Toyama Chemical Co., Ltd.: Research Funding; Alexion Pharmaceuticals, Inc.:: Research Funding; Nippon Shinyaku Co., Ltd: Research Funding; Shionogi & Co., Ltd.: Research Funding; Astellas Pharma Inc.: Research Funding; Asahi Kasei Pharma Corp.:: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; JCR Pharmaceuticals Co., Ltd.: Research Funding.
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