Donor lymphocyte infusion following allogeneic hematopoietic stem cell transplantation

Introduction: Allogeneic hematopoietic stem cell transplantation (SCT) is the treatment of choice for many malignant hematological disorders. Following recent improvements in non-relapse-related mortality rates, relapse has become the commonest cause of treatment failure. Infusion of donor lymphocytes can potentially enhance immune-mediated antitumor activity and offers a salvage option for some patients. This paper reviews the current literature on the efficacy of this therapeutic strategy.

Areas covered: The biology of adoptive cellular therapy with allogeneic immune cells to treat relapse across a spectrum of diseases in both the full intensity and reduced intensity hematopoietic SCT settings is explored. The review discusses the current limitations of the approach and reviews several new experimental strategies which aim to segregate the desired graft-versus-tumor effect from the deleterious effects of more widespread graft-versus-host reactivity.

Expert opinion: Durable responses to DLI have been noted in chronic myeloid leukemia and responses have also been described in acute leukemia, multiple myeloma and chronic lymphoproliferative disorders. The new challenge in transplantation is to optimize DLI therapy in order to further improve patient outcomes.     

Donor lymphocyte infusion in myeloid disorders

A number of modalities including both pharmaceutical and cell-based treatments have long been tested and developed to prevent and treat relapses after allogeneic stem cell transplantation (allo-HSCT). The ability of donor T cells to recognize antigenic structures on leukemic cell surfaces and destroy them is a well-known fact. Based on this fact, the idea of using donor T cells to contribute to the development of adoptive immunotherapy has emerged. Donor lymphocytes are easy to obtain and donor lymphocyte infusions (DLI) have a simple rational while this treatment modality is an effective example of cellular therapy. The group of chronic myeloid leukemia patients who are more likely to benefit from DLI include: a) patients in the chronic phase of hematologic relapse and b) patients with molecular/cytogenetic relapse. DLI appear to be an appropriate treatment option to be used in combination with conventional chemotherapy or hypomethylating agents in the treatment of post-allo-HSCT relapse for acute myeloid leukemia and myelodysplastic syndrome, if:) the burden of tumor is low b) the relapse is at a molecular level rather than an overt hematologic relapse c) the patient has favorable cytogenetic characteristics d) time interval between transplantation and relapse is relatively longer (>5 months) e) response could be obtained after salvage therapies. In the event that minimal residual disease (MRD) or increasing mixed chimerism is detected, prompt administration of DLI for prophylactic purposes without waiting for a manifest relapse, was found to be effective in inducing a full donor chimerism and overcoming MRD and eventually preventing a manifest relapse.     

供者淋巴细胞输注治疗HLA不合造血干细胞移植后白血病复发

目的 观察HLA不合造血干细胞移植(HSCT)后白血病复发患者中进行供者淋巴细胞输注(DLI)的有效性及安全性.方法 对HLA不合HSCT后复发患者进行G-CSF动员的DLI联合移植物抗宿主病(GVHD)预防、部分联合化疗,并观察GVHD发生、白血病缓解以及长期生存情况.结果 24例HSCT后白血病复发患者DLI后8例发生Ⅲ～Ⅳ度GVHD.短期GVHD预防可显著减少重度GVHD发生(P=0.020).8例发生慢性GVHD.3例出现骨髓抑制.16例白血病患者获完全缓解.9例无病存活,随访时间1310(961～1914)d.移植后1年和2年无病存活率分别为60%和40%.复发时骨髓幼稚细胞数量影响DLI后的缓解率和生存率,DLI后发生慢性广泛型GVHD与白血病完全缓解呈正相关(P=0.046).3例Ph阳性急性淋巴细胞白血病全部死于复发.结论 经G-CSF动员的DLI联合GVHD预防、部分联合化疗可以作为HLA不合HSCT后白血病复发的治疗手段.     

Hematopoietic stem cell transplantation for hematologic disorders

There have been a great progress in hematopoietic stem cell transplantation (SCT) for hematologic malignancies in various aspects including stem cell sources, supportive care, infrastructure, stem cell mobilization, etc., which has lead SCT from experimental therapy to standard medical practice. The most prominent is the advent of SCT with reduced-intensity conditioning (RIC) regimen. It has not only expanded the eligibility for SCT to patients of older age or with co-morbidities, but also highlighted the impact of graft-versus-tumor (GVT) effects in some malignant disorders such as follicular lymphoma, peripheral T-cell lymphoma, and chronic myeloid or lymphocytic leukemia. RIC will provide a possibility for myriads of newly developed molecular-targeted or antibody-based agents to be incorporated in SCT as pre- or post-SCT therapies.     

Clinical study on the relapsd leukemia patients with graft versus host disease after allogeneic hematopoietic stem cell transplantation

OBJECTIVE: To explore the dissociation of graft-versus-leukemia (GVL) effects from graft-versus-host disease (GVHD) in the patients who experienced GVHD during leukemia relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: The primary disease, disease status, GVHD, response to donor lymphocyte infusion (DLI) and prognosis were analysed in 11 leukemia patients who relapsed with GVHD after allo-HSCT. RESULTS: Of the 11 relapsed, 5 were acute lymphoblastic leukemia and 6 acute myeloid leukemia. Five received DLI before relapse and all developed post-DLI GVHD, including 2 grade II acute GVHD (aGVHD), 1 limited chronic GVHD (cGVHD) plus grade II aGVHD, and 2 extensive cGVHD. After relapse of the 5 patients, 2 received Chemo-DLI, one achieved CR with extensive cGVHD and then relapsed again, the other didn't achieved CR. The other 6 patients didn't received DLI before relapse and also developed post-HSCT GVHD while relapsing, including 3 extensive cGVHD, 1 grade I aGVHD and 2 grade II-IV aGVHD. After relapse, these 6 patients received Chemo-DLI, 2 achieved CR and then relapsed again, 4 didn't achieved CR. CONCLUSION: The elicited GVHD after allo-HSCT may not accompany effective GVL effects inhibiting leukemic relapse.     

异基因造血干细胞移植后白血病复发伴活动性移植物抗宿主病患者的临床研究

目的 探讨异基因造血干细胞移植(allo-HSCT)后白血病复发伴活动性移植物抗宿主病(GVHD)患者GVHD与GVL效应的分离.方法 分析11例接受allo-HSCT后在白血病复发时存在活动性GVHD的患者其原发病、疾病状态、复发时GVHD类型、供者淋巴细胞输注(DLI)疗效及转归等对GVL效应的影响.结果 11例患者包括急性淋巴细胞白血病5例,急性髓系白血病6例,其中5例曾行预防性DLI,复发时伴有活动性DLI后GVHD,包括2例Ⅱ度急性GVHD(aGVHD),1例原局限型慢性GVHD(cGVHD)加重+新发Ⅱ度aGVHD,2例广泛型cGVHD;这5例患者复发后,2例行化疗+治疗性DLI,DLI后在广泛型cGVHD反复加重情况下,1例达完全缓解(CR)后再次复发,1例未达CR.另6例患者复发前未行预防性DLI,白血病复发时亦均存在活动性GVHD,包括3例广泛型cGVHD、1例Ⅰ度aGVHD及2例Ⅲ～Ⅳ度aGVHD,复发后行化疗+治疗性DLI,之后2例达CR后再次复发,4例未达CR.结论 allo-HSCT后活动性GVHD不一定伴随可抑制白血病复发的有效GVL效应.     

Donor lymphocyte infusion therapy

Donor lymphocyte infusion (DLI), which is therapy typically used after stem cell transplant, is a relatively new therapeutic intervention. It has been used in a number of hematopoietic malignancies, for some solid tumor malignancies, for its viral modulation effects, and as a prophylactic approach in the prevention of recurrent disease. The efficacy of this therapy is most evident in patients who have chronic myelogenous leukemia. However, studies of other diseases have been less forthcoming in showing clear benefit. Even in patient groups in which disease remission has been attributed to DLI, the risks of the treatment, namely graft-versus-host disease, may invalidate its use. This article summarizes a number of key studies addressing its usefulness in a number of disease states, risks of therapy, and strategies to ameliorate those risks while preserving benefit. It also examines tools that have been developed to more accurately describe survival benefits attributable to DLI.     

Infusion of allogeneic natural killer cells in a patient with acute myeloid leukemia in relapse after haploidentical hematopoietic stem cell transplantation

BACKGROUND: Allogeneic donor natural killer (NK)‐cell infusion (NK‐DLI) is a promising immunotherapy for patients with hematologic disorders. CASE REPORT: This report describes the case of a patient who received a single haploidentical NK‐DLI for a relapse of acute myeloid leukemia (AML) after haploidentical hematopoietic stem cell transplantation. He underwent a cytoreductive, immunosuppressive regimen before NK‐DLI and received high‐dose interleukin‐2 in vivo for 8 weeks afterward. RESULTS: No major adverse effect was observed. Prospective phenotypic and functional studies of the NK cells showed major expansion of infused NK cells and, more importantly, of the alloreactive KIR2DL1+KIR2DL2/DL3–NKG2A– subset, which reached 117 × 10⁶ cells/L on Day +14 after NK‐DLI, the greatest expansion of infused alloreactive NK cells reported so far. Infused NK cells conserved their lytic capacities against K562 target cells and primary AML‐mismatched blasts. CONCLUSION: We review the literature to clarify these data and to detail the indications for allogeneic NK‐DLI, the criteria for determining the most suitable donor, the types of conditioning regimens, and the procedures for selecting and activating NK cells.     

Imatinib mesylate in conjunction with allogeneic hematopoietic stem cell transplantation in patients with Philadelphia chromosome positive leukemias: report of 4 cases

We described here four patients diagnosed with Philadelphia chromosome positive (Ph+) leukemia, consisting of chronic myeloid leukemia (CML) (n=2) and Ph+ acute lymphoblastic leukemia (ALL) (n=2). All patients were treated with imatinib mesylate (300-400 mg/day) for the treatment of relapsed CML after allogeneic hematopoietic stem cell transplantation (SCT) (n=2), relapsed Ph+ ALL after SCT (n=1), and Ph+ ALL preceding SCT (n=1). Significant clinical and molecular responses were observed in all patients and three of them achieved sustained molecular remission. Imatinib was well tolerated and did not induce noticeable graft versus host disease although one patient presented severe skin rash (Grade III). Notably, serum cyclosporine A concentration increased after the initiation of imatinib treatment, probably through competitive inhibition of P450 3A4 isoenzyme. Our data suggest that imatinib in conjunction with SCT for the Ph+ leukemia may be a promising treatment strategy.     

混合骨髓移植后过继免疫治疗小鼠白血病

背景：急性白血病自体造血干细胞移植后复发率高,异基因造血干细胞移植后移植相关病死率高,混合造血干细胞移植及移植后过继免疫治疗有可能取长补短,提高疗效。目的：观察自体骨髓混合H-2半相合异体骨髓移植后供体淋巴细胞输注＋白细胞介素2治疗对小鼠白血病的疗效。方法：将Balb/c小鼠经直线加速器照射3Gy后分为白血病模型组、白血病模型照射组、混合移植组、自体骨髓移植组,均尾静脉注射5×10^5K562（GFP＋/NeoR＋）或K562（GFP-/NeoR-）细胞。7d后6Gy照射,自体骨髓移植组移植自体骨髓细胞或联合白细胞介素2治疗;混合移植组移植小鼠自体骨髓细胞混合1/10的H-2半相合异体骨髓细胞后应用白细胞介素2或联合供体淋巴细胞输注治疗。4周后行小鼠外周血及骨髓细胞形态检查,外周血细胞亚群、GFP及NeoR基因测定,肝、脾匀浆细胞GFP和NeoR基因测定。结果与结论：白血病模型组小鼠因骨髓造血功能衰竭于20d内全部死亡,白血病模型照射组小鼠因造血功能衰竭于14d内全部死亡;自体骨髓移植组、混合移植组均有多少不等小鼠无白血病存活超过28d,且混合骨髓移植后及自体骨髓移植后应用白细胞介素2治疗可提高白血病小鼠长期无病生存率,在此基础上联合供体淋巴细胞输注可更进一步提高白血病小鼠长期无病生存率。     

异基因造血干细胞移植治疗复发难治性急性淋巴细胞白血病的临床研究

目的 探讨异基因造血干细胞移植(allo-HSCT)对复发难治性急性淋巴细胞白血病(ALL)患者的疗效及治疗相关毒性.方法 观察并分析47例复发难治性ALL患者对allo-HSCT治疗的耐受情况、移植相关并发症、总生存率以及无病存活率.其中HLA相合同胞间移植(sib-HSCT)19例,HLA相合的无血缘关系移植(URD-HSCT)18例,单倍型移植(Hi-HSCT)10例.预处理方案:42例采用改良TBI+CY方案,5例采用改良BU/CY方案.移植物抗宿主病(GVHD)的预防:环孢素(CsA)联合短程甲氨蝶呤(MTX)、Hi-HSCT和URD-HSCT加用霉酚酸酯(MMF)及抗胸腺细胞免疫球蛋白(ATG).定期监测微量残留病变(MRD),明确有分子生物学或细胞遗传学复发趋势的患者接受供者淋巴细胞输注(DLI).结果 所有患者均完成移植治疗,出现了不同程度黏膜炎;2例患者在应用CsA过程中有肾功能损害;1例患者发生药物性癫痢.移植后出现Ⅲ～Ⅳ度急性GVHD 7例;慢性GVHD22例;致命性肺部感染9例(包括间质性肺炎3例);出血性膀胱炎4例.有13例患者移植后再次复发.移植后造血重建的中位时间为移植后第17天.术后有19例接受DLI,6例疾病未再进展.中位随访期43(10～77)个月,预期5年总生存率为49.65%,无病存活率为46.55%.结论 统 allo-HSCT能有效治疗复发难治性ALL,改善其预后,治疗失败的主要原因是移植后复发,其次为致命性肺部感染和重度急性GVHD.DLI可能有助于减少移植后复发.     

自体造血干细胞移植治疗急性白血病的研究进展

经过近40年的发展,自体造血干细胞移植(AHSCT)在急性白血病治疗中的地位和作用不断变化.AHSCT的主要优势为移植相关死亡率低和移植后患者生活质量高,其主要问题为移植后复发率高.预后良好及不适合异基因造血干细胞移植(allo-HSCT)的急性髓细胞白血病(AML)患者可受益于AHSCT;在酪氨酸激酶抑制剂(TKI)靶向治疗时代,对TKI反应良好的ph+-急性淋巴细胞白血病(ALL)患者进行AHSCT治疗后,可提高其远期生存质量.为了提高AHSCT治疗急性白血病的疗效,AML患者应在化疗缓解后强化治疗2～3个疗程进行AHSCT治疗,ALL患者则应在化疗缓解后强化治疗3～5个疗程进行为宜.ALL患者在接受AHSCT治疗后,还应进行移植后维持治疗.     

Hemopoietic chimerism following stem cell transplantation.

Hematopoietic chimerism is a measure of the number of donor and recipient cells in the host following stem cell transplantation (SCT). The type of conditioning therapy prior to SCT has a major impact on the chimeric status in the recipient. Different techniques of measurement have varying sensitivities. The use of polymerase chain reaction (PCR) of short tandem repeats (STR) using fluorescent amplification permits quantification using Genescan analysis. When SCT is used for malignant haematological disorders, measurement of chimeric status may indicate early relapse and in aplastic anemia graft rejection. Reduced intensity or T-cell depletion is associated with mixed haemopoietic chimerism. SCT for benign haematological disorders does not require complete donor chimerism for a successful outcome.     

第二次移植治疗异基因造血干细胞移植后复发白血病的临床研究

目的　评价第二次异基因造血干细胞移植 (allo HSCT)治疗allo HSCT后复发白血病的疗效。方法　回顾分析因allo HSCT后复发而进行第二次allo HSCT的 1 0例白血病患者临床资料。其中急性髓系白血病 5例 ,急性淋巴细胞白血病 4例 ,慢性髓系白血病 1例。第一次HSCT后中位复发时间 1 4 1d(34～ 5 4 5d)。第二次HSCT时预处理方案包括 :以中剂量阿糖胞苷 (Ara C)为主的联合化疗 5例 ;以白消安为主的联合化疗 3例 ;含常规剂量Ara C的联合化疗 1例 ;氟达拉宾 /马法兰 1例。移植物抗宿主病 (GVHD)预防方案 :单用环孢菌素 (CsA) 2例 ,CsA 短疗程甲氨蝶呤 1例 ,短疗程他克莫司 1例 ,6例未预防。输注外周血单个核细胞中位数 6 .1× 1 0 8/kg[(1 .9～ 1 1 .8)× 1 0 8/kg]。 结果　可评价的 8例患者均造血重建 ,达中性粒细胞绝对值 >0 .5× 1 0 9/L、血小板 >2 0× 1 0 9/L中位时间分别为移植后 1 1d(3～ 1 7d)、1 2d(9～ 2 3d)。发生Ⅰ度急性GVHD 4例 ,Ⅱ度急性GVHD 3例。可评价的 6例中 5例发生局限型慢性GVHD。 2例无病生存 986d和 1 91 3d。移植相关死亡 5例。复发 3例 ,均死亡。 2年实际无病生存率、移植相关死亡率、复发率分别为 2 0 %、5 0 %和 30 %。结论　第二次allo HSCT是治疗allo HSCT后复发白血病的有效     

The use of monoclonal antibodies for the treatment of graft-versus-host disease following allogeneic stem cell transplantation

INTRODUCTION: Graft-versus-host disease (GVHD) remains the leading cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Steroids along with calcineurin inhibitors remain the standard initial therapy, however, less than half of the patients completely respond and there is no uniformly accepted therapy for patients with steroid-resistant GVHD. AREAS COVERED: This paper reviews the current role and ongoing development of mAbs in the treatment of GVHD. Various mAbs to cell surface antigens on GVHD effector cells have been investigated for the treatment of acute GVHD: these include anti-TNF-α antibodies, IL-2 receptor antagonists, anti-CD3 and anti-CD52 mAbs, while anti-CD20 mAb has been extensively investigated in the setting of chronic GVHD. Overall, response rates have been reported to be greater than 60%, although it should be emphasized that the long-term survival still remains suboptimal, mainly due to the detrimental side effects of infectious complications, progressive GVHD and relapse of underlying malignancy. EXPERT OPINION: Future challenges will include more appropriate definition of these agents in the therapeutic scenario of GVHD. Combinations of mAbs or mAb combined with newer immunosuppressive drugs might potentially achieve greater success, especially if used early in the disease process.     

Non-myeloablative/reduced-intensity hematopoietic stem cell transplantation for chronic myelogenous leukemia]

Allogeneic hematopoietic stem cell transplantation(HSCT) is a curative therapy against a variety of hematological disorders. However, its application has been limited to younger patients without organ dysfunctions due to transplant-related toxicities. Recently, non-myeloablative stem cell transplantation(NST) or reduced-intensity stem cell transplantation(RIST) has been developed as a less toxic HSCT, which enables the application of HSCT to patients of advanced age or with organ dysfunction. The anti-leukemia effect mainly depends on the graft-versus-leukemia(GVL) effect. Chronic myelogenous leukemia(CML) has been known to be one of the best targets for GVL effect, supported by the observation of durable molecular remission after donor lymphocyte infusion for relapse after HSCT. RIST could be a promising treatment modality for patients with CML.     

Novel approaches to allogeneic stem cell therapy

Traditionally, allogeneic haematopoietic stem cell transplantation (SCT) has involved administration of myeloablative doses of chemotherapy and/or radiation that may cure many patients with haematologic diseases. The high morbidity and mortality associated with the intensive conditioning regimen limits allogeneic SCT to younger and healthier patients. However, it is now known that successful allogeneic SCT is dependent, at least in part, on the antitumour properties of the donor graft independent of the conditioning regimen. This potent ‘graft versus tumour’ (GVT) effect can now be exploited for clinical benefit. The best evidence of a direct GVT reaction comes from the use of donor leukocyte infusions (DLI). For many patients with relapsed leukaemia after allogeneic SCT, DLI re-establishes complete and durable remissions. This has suggested a novel approach to allogeneic cell therapy (ACT) using non-myeloablative, but immunosuppressive conditioning regimens to permit engraftment of allogeneic stem cells and lymphocytes. Engrafted donor cells would then provide GVT activity in the setting of reduced conditioning regimen toxicity. The ability to minimise toxicity and maximise the immunologic GVT effect will make allogeneic transplantation applicable to patients typically ineligible for conventional allogeneic SCT. Response rates with this strategy have been impressive, although toxicity related to graft versus host disease (GVHD) and other complications remains a concern. Current trials have involved heterogeneous groups of patients using various conditioning regimens. Many issues remain unsettled, including identification of the most appropriate tumour targets and definition of the most effective, least toxic conditioning regimen. In addition, the durability of response is unknown. Nevertheless, the use of non-myeloablative conditioning and ACT may provide a new paradigm for allogeneic cell transplantation and the immunotherapy of cancer.     

异基因反应性NK细胞在供者淋巴细胞输注治疗单倍体相合造血干细胞移植后肺癌复发中的作用研究

本研究旨在探讨预处理中并基因反应性NK细胞（allo—reactive NK cells,Allo—NK）在供者淋巴细胞输注（DLI）治疗单倍体相合造血干细胞移植后肺癌复发中的作用。采用免疫磁珠富集F1供鼠（H-2^d/b）脾脏allo—NK,流式细胞术和LDH法检测其异体反应性。建立小鼠单倍体相合造血干细胞移植后肺癌复发模型,采用放射性核素标记法追踪DLI的体内分布。比较不同处理组小鼠的肿瘤大小、淋巴细胞浸润程度,采用RayBio小鼠细胞因子抗体芯片检测血清中22种细胞因子的变化。结果表明：在移植后24—48小时,allo—NK组的回输供者淋巴细胞在受者肺脏、脾脏、肾脏中明显蓄积,浓度最高,时间最长。化疗＋DLI组与化疗＋PBS组的肿瘤体积相比无明显区别,但allo．NK＋DLI组的肿瘤体积显著小于化疗＋DLI组（P〈0．05）和allo—NK＋PBS组（P〈0．01）组,且镜下可观察到肿瘤局部较多的淋巴细胞浸润。allo—NK＋DLI组中MCP-1、IL-17、IL—12和MCP-5较对照组分别升高1．56、1．36、1.20、1．17倍;而IL-10降低42．8％。结论：allo-NK可以延长DLI在宿主体内停留时间,促进炎性因子和Th1类细胞因子分泌,抑制肿瘤生长,提高DLI治疗移植后肺癌复发的疗效。     

Adoptive allogeneic immunotherapy--history and future perspectives

For more than 30 yrs allogeneic hematopoietic stem cell transplantations have been successfully performed in patients with hematologic malignancies and bone marrow aplasia. Over the years the field of transplantation has changed dramatically. More and more unrelated donors became available, regimens for haploidentical transplantations were introduced and G-CSF mobilized peripheral blood stem cells and fetal cells from umbilical cord became available as alternate sources of hematopoietic stem cells. However, especially the introduction of donor lymphocyte infusions (DLI) for the successful treatment of leukemic relapses after allogeneic stem cell transplantations improved our understanding of transplantation immunology and opened amazing perspectives in allogeneic transplantation. It was long believed, that myeloablative therapy with high-dose chemotherapy and total body irradiation (TBI) are the sole antileukemic principles in allogeneic transplantations. But by now it became clear, that donor lymphocytes exert a very potent antileukemic effect, now referred as the graft-versus-leukemia (GVL) or graft-versus-malignancy (GVM) reaction. The efficacy of DLI in controlling leukemic relapses suggests that myeloablative therapy is not essential for long-term disease control. By exploiting the GVL or GVM reaction more intensively the role of chemotherapy and TBI is changing to immunosuppression. Sufficient immunosuppression to allow grafting, however, can be achieved with much lower doses as those which have been used in conventional transplants. Therefore allogeneic transplants have become also available for the elderly or for patients with concurrent medical conditions, which would have excluded them from conventional transplants. Moreover, this allogeneic transplantation strategy with reduced intensity conditioning is now also under investigation in patients with susceptible solid tumors and autoimmune diseases. However, one major obstacle in allogeneic transplantations, namely the graft-versus-host disease (GVHD), remains to be solved.     

Treatment plan and informed consent]

Since STI571, a BCR-ABL tyrosine kinase inhibitor, has made a great therapeutic advance in the management of CML, we have to reconsider the treatment protocol for chronic phase CML. Interferon-alpha (IFN-alpha) will be replaced with STI571 therapy. However, some patients are reported to become refractory to STI571, and it is unclear whether STI571 therapy alone may be sufficient to induce long-term survival in CML. There are also important progress in the field of allogeneic hematopoietic stem cell transplantation (SCT); i.e. minitransplant(non-myeloablative SCT) and cord blood stem cell transplantation. Currently, newly-diagnosed CML patients in chronic phase should be initially treated with STI571. If the patients are appropriate candidates for allogeneic SCT and have HLA-indentical sibling donors, allogeneic SCT should be conducted within one year. The other patients should also receive related or unrelated allogeneic SCT if Ph suppression is insufficient with STI571 therapy for several months. The patients who are not candidates for allogeneic SCT may be treated with IFN-alpha and/or Hydrea(or cytosine arabinoside) in addition to STI571 if they become refractory to STI571. Since each therapeutic modality has different risk and benefits, informed consent is very important to determine the treatment plan for individual patients.