自体外周血造血干细胞移植联合Mylotarg治疗急性髓系白血病一例并文献复习

 目的　探讨减少急性髓系白血病（AML）自体外周血造血干细胞移植（auto-PBSCT）后复发的新方法。方法　报道1例auto-PBSCT联合抗CD33单抗（Mylotarg）治疗的AML患者，并通过长期随访了解治疗效果。结果　该患者无瘤生存3年。结论　auto-PBSCT联合Mylotarg可能为auto-PBSCT后减少白血病复发提供新的治疗方案，同时为Mylotarg的临床应用提供新途径。     

博纳吐单抗治疗急性淋巴细胞白血病的研究进展

近年来,随着免疫治疗和造血干细胞移植技术（hematopoietic stem cell transplantation,HSCT）的发展,急性淋巴细胞白血病（acute lymphoblastic leukemia,ALL）的缓解率逐渐升高,但复发难治性ALL的预后仍旧很差。博纳吐单抗（blinatumomab）作为一个新型的CD3和CD19双特异性抗体在复发难治性ALL中均获得较好的疗效,并于2014年12月被美国食品药品监督管理局（FDA）批准用于复发难治性急性B淋巴细胞白血病（B-cell acute lymphoblastic leukemia,B-ALL）的治疗。博纳吐单抗单药治疗初治ALL及联合化疗药物、酪氨酸激酶抑制剂治疗ALL均可改善患者生存期。本文主要围绕博纳吐单抗的临床试验、不良反应等方面的最新研究进行阐述。      

成人急性髓系白血病的免疫学特点及预后

目的：探讨急性髓细胞白血病（AML）的免疫表型特点。方法：使用淋系和髓系单抗,用间接免疫荧光法对70例原发性AML进行免疫表型分析。结果：所有AML患者的细胞至少被1种髓系单抗标记,各髓系抗原的表达率依次为CD33＞CD13＞CD15。所有M3患者CD9为阳性。16／70例（30％）表达CD34抗原、CD34^ AML组在年龄、外周血象及骨髓原始、幼稚细胞比例等方面与CD34^-组相比较无显著差别,但表达CD34抗原的AML常伴有HLA－DR、CD38、CD7等不成熟细胞表面标记的表达,而较成熟的髓系细胞表面标记CD15则不表达。70例AML中有16例表达淋系抗原,CD4^ 例（13．8％,M2为8．8％,M460％）;CD7^ 9例（16．9％,M1为50％,M218％,M5b16．7％）。CD4^ 的AML患者CD34为低表达,CD33表达。结论：CD9^ 、CD34^-、HLA－DR^-及CD13^ 、CD15^ 是典型M3的免疫表型特点。CD34^ AMLgn AML-M1有着密切的关系,且对化疗反应较差,证明CD34^ 的AML是一组分化程度较差的类型;提示CD7^ 和CD4^ 的AML预后差,CD7^ 的AML的一种独特类型。     

博纳吐单抗治疗急性B淋巴细胞白血病的疗效和安全性

博纳吐单抗作为靶向CD19和CD3的新型双特异性抗体, 可诱导T淋巴细胞精准靶向CD19阳性B淋巴细胞使其凋亡, 是目前国内唯一被批准用于治疗血液恶性肿瘤的双特异性抗体, 对初诊断、复发/难治性、微小残留病阳性的急性B淋巴细胞白血病(B-ALL)患者有较好的疗效, 可改善患者生存期, 且耐受性良好。对其深入研究可为博纳吐单抗用于B-ALL患者的诱导治疗、挽救治疗和序贯造血干细胞移植提供理论依据和新的思路。     

白血病干细胞研究进展

白血病干细胞(leukemia stem cells,LSC)是白血病患者耐药和复发的根源.有关白血病干细胞起源的假说存在三种不同的观点.目前可以通过白血病干细胞特异性抗体将其与正常造血干细胞(HSC)区分开来.CD123是存在于AML LSC表面的重要抗原,CD33仅在部分AML LSC上表达,CD96、CD44和c-型凝集素分子1(c-type lectin-like molecule-1,CLL-1)是新发现的LSC表面标记.白血病干细胞存在着独特的自我保护机制,靶向杀灭白血病干细胞是彻底治愈白血病的重要途径.     

抗CD123抗体靶向治疗急性髓系白血病

白血病干细胞（leukemic stem cells,LSCs）被认为是白血病发生、发展、耐药、复发的根源,如何彻底根除LSCs已成为白血病治疗研究的一个重要方向。CD123是LSCs表面相对特异的抗原,针对其研发的靶向抗体治疗药物可有效杀伤急性髓系白血病（acute myeloid leukemia,AML）的LSCs,本文对抗CD123抗体靶向治疗AML的最新进展做一综述。     

t(8;21)急性髓系白血病患者MICM分型及预后的回顾性分析

 目的　分析t(8;21)急性髓系白血病（AML）患者的细胞形态学、免疫表型、遗传学、分子生物学（MICM）分型及临床治疗疗效。方法　运用瑞特染色法、FAB细胞形态分类标准、流式细胞术（FCM）直接免疫荧光标记技术、遗传学染色体吉姆萨显带技术及RT-PCR技术对70例确认有t(8;21)与AML1-ETO融合基因双阳性的AML患者及70例正常染色体核型的AML患者进行分析和比较。结果　70例t(8;21)AML患者中M1 1例,M2 64例,M4 3例,无法分型的急性白血病（AL）2例;免疫表型分析发现CD13、CD33、CD34、CD117高表达,40 %表达CD19,11 %表达CD15,10 %表达CD11b,7 %表达CD7;遗传学显示50 %的t(8;21) AML患者有附加染色体异常,主要为性染色体丢失、9q-及超二倍体;RT-PCR检测AML1-ETO融合基因100 %阳性。CD+19 t(8;21) AML患者完全缓解（CR）率72 %,CD+19伴CD+7 t(8;21)AML患者CR率为0,正常核型CR率31 %。结论　t(8;21) AML患者主要在M2中集中出现,附加染色体异常较多见。CD19表达较高,而CD7表达极低,CD34、CD117高表达,这些抗原的表达可能与核型密切相关。CD+19 是预后良好的指标,但同时出现CD+7,则预后不良。     

139例急性髓系白血病免疫分型特点分析

目的探讨急性髓性白血病（AML）的免疫分型特点及意义。方法采用单克隆抗体和流式细胞仪检测AML的免疫表型。结果（1）139例AML病例中各种抗原的阳性表达率依次为为MPO（92.1%）,CD33（92.1%）,CD13(89.2%),其中53例AML伴淋巴系抗原表达,分别为CD19(20.9%),CD7(16.2%),CD2(7.2%),CD10(0.72%)。(2)CD14在M4、M5型AML中高表达。(3)干祖细胞分化抗原表达率依次为CD117（83.8%）〉HLA DR(80.3%)>CD34(67.6%),CD34阳性的完全缓解率（CR）分别明显低于CD34阴性组（P=0.034）。（4）CD7阳性患者CR明显低于其抗原表达阴性者（P=0.041）。结论白血病免疫分型能确诊某些特殊类型的白血病,对免疫分型的研究将有助于指导临床诊断、治疗及判断预后。     

混合谱系白血病-AF6融合基因阳性急性髓系白血病八例临床特点与预后

目的 探讨混合谱系白血病（MLL）-AF6融合基因[t（6;11） （q27;q23）]阳性急性髓系白血病（AML）患者的临床特点与预后.方法 收集安徽省立医院血液内科住院初治MLL-AF6融合基因阳性的AML患者8例,利用多重巢式反转录-聚合酶链反应（RT-PCR）检测治疗前后MLL-AF6融合基因动态变化,分析患者临床特征、免疫表型、细胞遗传学、患者首次诱导治疗后完全缓解（CR）率、总体生存率、造血干细胞移植效果与患者预后的关系.结果 2009年2月至2013年8月住院患者确诊为急性白血病（AL）患者472例,其中AML患者285例,包括MLL-AF6融合基因阳性AML患者8例,占AL的1.69％（8/472）,占AML的2.80％（8/285）.MLL-AF6融合基因阳性AML患者按WHO分型：M11例,M22例,M42例,M53例,以M4/M5为主（5例）.8例AML患者首次化疗后CR 5例,总体生存4例.4例单纯化疗患者中,有2例在第1个疗程结束后MLL-AF6融合基因转阴,且1例获得了血液学CR并已生存26个月,1例初诊后6个月复发,后经治疗后死亡;2例患者第1个疗程结束后MLL-AF6融合基因未转阴（1例转为弱阳性,1例仍为阳性）,均未获得血液学CR且死亡.4例造血干细胞移植患者中,3例移植前MLL-AF6融合基因转阴,均无复发,仍生存,平均生存时间28个月;1例患者移植前MLL-AF6融合基因未转阴（弱阳性）,移植后复发死亡.结论 MLL-AF6融合基因阳性AML患者在AML-M4/M5中发生率高,发病时常伴有高白细胞、器官浸润,且治疗效果差,易复发,预后差,造血干细胞移植可显著改善患者预后.RT-PCR检测治疗前后MLL-AF6融合基因的动态变化可在一定程度上帮助判断患者预后.     

急性白血病患者造血干细胞P-选择素表达的研究

 目的　研究急性白血病（AL）患者骨髓白血病干细胞表面分子P-选择素（CD62P）的表达情况及其临床意义。方法　采用流式细胞术（FCM）检测56例初治AL患者骨髓CD62P的表达情况,以15例健康成年人骨髓标本为对照。结果　38例急性髓系白血病（AML）患者干细胞（CD+45 CD+34 CD-38）中CD62P平均表达水平为（6.72±7.64）%,12例急性B淋巴细胞白血病（B-ALL）患者干细胞（CD+45 CD+34 CD+19）为（3.46±2.51）%,6例急性T淋巴细胞白血病（T-ALL）患者干细胞（CD+45 CD+34 CD+7）为（6.23±4.95）%,均明显高于健康对照组[（1.04±1.23）%]（t值分别为2.847、3.284、3.091,P＜0.01）。经过正规方案治疗后,完全缓解组患者CD62P表达与健康对照差异无统计学意义（t＝0.397,P＞0.05）。另外CD+62P的AML及T-ALL患者白细胞计数、血红蛋白及血小板计数均明显高于CD-62P 患者（t值分别为4.153、8.095、8.289、7.235、8.692、9.832,P＜0.05）;而CD+62P与CD-62P的B-ALL患者无明显差异（t值分别为0.340、1.142、0.019,P＞0.05）。结论　CD62P是血小板活化的标志物之一,在不同类型的AL中有不同程度的表达。AL骨髓造血干细胞中CD62P可能作为白血病造血干细胞的标志,以及临床疗效观察预后判断的指标之一。     

CD 33 as a target of therapy in acute myeloid leukemia: current status and future perspectives

CD33 is a myeloid cell surface antigen that is expressed on blast cells in acute myeloid leukemia (AML) in a majority of all patients regardless of age or subtype of disease. The antigen is also expressed on leukemic stem cells in many cases, but is not expressed on normal hematopoietic stem cells. In an attempt to improve therapy in AML, a CD33-targeted drug has been developed. The drug, gemtucumab ozogamicin (GO; Mylotarg®), consists of a humanized CD33 antibody (hP67.6), a pH-dependent linker, and a highly potent chemotherapy agent, calicheamicin 1,2,-dimethyl hydrazine dichloride. Based on its clinical activity, GO has been approved for application in chemotherapy-refractory AML in various countries and is effective as a monosubstance as well as in combination with conventional chemotherapy. However, despite high efficacy and a certain specificity for leukemic (as opposed to normal) stem cells, the drug does not work in all patients, and can produce significant side-effects, including veno-occlusive disease (VOD), especially in patients who undergo stem cell transplantation. These side-effects have to be balanced against the benefit of GO therapy in patients with relapsed or refractory AML.     

Long-term complete remission after single therapy with gemtuzumab ozogamicin for refractory AML in an elderly patient

Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 monoclonal antibody conjugated to calicheamicin, that is rapidly internalized after binding to CD33. This is followed by intracellular release of calicheamicin, which induces double-stranded DNA breaks, cell cycle arrest, and apoptosis. So GO is a more selective agent for acute myeloid leukemia (AML), because the CD33 antigen is expressed on AML, while it is not expressed on normal hematopoietic stem cells and nonhematopoietic tissues. However, some studies indicated that this agent showed resistance to refractory AML cells via various mechanisms, and that there were no potent effects. In this study, we report a 76-year-old female with recurrent AML who responded to single therapy with GO, achieving complete remission for more than 1 year after the start of administration, although additional remission induction was impossible. The response to GO can be stratified with reference to the response to conventional chemotherapy.     

What role does gemtuzumab ozogamicin have in the treatment of acute myelogenous leukemia?

Gemtuzumab ozogamicin (GO) is a novel, targeted chemotherapy designed to treat acute myeloid leukemia (AML). GO consists of an antitumor antibiotic, calicheamicin, linked to a humanized monoclonal antibody against CD33. It has been approved in the United States since 2000 to treat CD33+ AML in first relapse in older adults who are not candidates for cytotoxic therapy. Beyond this indication, the role of GO is evolving. Single-agent GO has a limited role in de novo AML. Incorporation of GO into standard induction treatment in de novo and relapsed AML is feasible. Comparative phase III studies of such an approach are ongoing. GO is associated with serious toxicities, such as infusional reactions, transient liver function test abnormalities, and veno-occlusive disease of the liver, especially in patients who undergo hematopoietic stem cell transplantation.     

CD33-directed therapy with gemtuzumab ozogamicin in acute myeloid leukemia: progress in understanding cytotoxicity and potential mechanisms of drug resistance.

CD33 is expressed on the malignant blast cells in most cases of acute myeloid leukemia (AML) but not on normal hematopoietic pluripotent stem cells. Antibody-based therapies for AML have, therefore, focused on CD33 as a suitable tumor-associated target antigen. The most promising results have been obtained with gemtuzumab ozogamicin (GO, Mylotarg), a humanized IgG(4) anti-CD33 monoclonal antibody joined to a calicheamicin-gamma(1) derivative. Engagement of CD33 by GO results in immunoconjugate internalization and hydrolytic release of the toxic calicheamicin moiety, which, in turn, causes DNA damage and cell death. Since 2000, when GO was approved for clinical use, treatment trials and pilot studies have revealed potential expanded applications along with additional limitations. At the same time, correlative biological and in vitro functional studies have further characterized CD33 expression patterns in AML, the significance of CD33-antibody interactions, pathways involved in GO-induced cytotoxicity and potential drug resistance mechanisms. This review summarizes the recent data addressing mechanisms of GO action and discusses their relevance with regard to clinical applications and the limitations of using experimental model systems to mimic in vivo conditions. As the first drug conjugate approved for clinical use, GO serves as an important paradigm for other immunoconjugates against internalizing tumor antigens.     

The role of gemtuzumab ozogamicin in the treatment of acute myeloid leukemia patients

Gemtuzumab Ozogamicin (GO) targets leukemia cells expressing CD33 by means of a monoclonal antibody conjugated to a cytotoxic agent, calicheamicin. GO has been approved in Japan as monotherapy for the treatment of patients with relapsed/refractory acute myeloid leukemia (AML)since 2005. GO administered as a single agent has resulted in overall response rates of about 30% in previously relapsed adult AML. Preliminary data indicate a potential role for GO also as a component of induction or consolidation regimen. Although caution is advised when administering GO within 115 days of a stem cell transplantation (SCT) procedure because of veno-occlusive disease, recent clinical studies overseas suggest that GO can be integrated into reduced-intensity conditioning therapy before allogeneic SCT in patients with relapsed AML. In order to reduce toxicity and improve efficacy, its optimal dose and schedule should be defined by large clinical trials.     

Use of Gemtuzumab Ozogamicin in Acute Myeloid Leukemia

Conventional chemotherapeutics and allogeneic hematopoietic cell transplantation are ultimately often unsuccessful in acute myeloid leukemia (AML). Antibody-based therapies targeting CD33, a myeloid differentiation antigen expressed on at least some AML cells in almost all patients and possibly on leukemia stem cells in some, have long been pursued to improve these outcomes. Most widely studied is gemtuzumab ozogamicin (GO), a humanized anti-CD33 antibody conjugated to a toxic calicheamicin

Acknowledgements

R.B.W. is a Leukemia & Lymphoma Society Scholar in Clinical Research.

     

Targeted therapy of acute myeloid leukemia with monoclonal antibodies and immunoconjugates

Traditional chemotherapy for acute leukemia often causes life-threatening toxic effects due to a lack of specificity for hematopoietic cells. Monoclonal antibodies and fusion proteins that target cell surface antigens on leukemic blasts are being evaluated for their cytotoxic effects and as a means of delivering chemotherapeutic agents or radiation directly to malignant cells. It is hoped that this strategy might selectively ablate malignant cells without many of the toxic effects commonly associated with conventional chemotherapy. In acute myeloid leukemia (AML), the cell surface antigens CD33 and CD45 are especially suitable targets. Although CD33 is expressed on AML blast cells from about 90% of patients, normal hematopoietic stem cells lack this antigen, as do essentially all nonhematopoietic tissues. For that reason, anti-CD33 antibodies have been created to target malignant myeloid and immature normal cells selectively while sparing normal stem cells. Anti-CD33 antibodies have also been used to deliver radiation or a cytotoxic agent directly to leukemic cells. Since the vast majority of leukemias and normal stem cells express the cell surface antigen CD45, another targeting approach allows the delivery of myeloablative radiation to bone marrow and spleen, common sites of leukemic involvement. Consequently, ¹³¹I-labeled anti-CD45 antibody has been combined with traditional preparative regimens for patients receiving bone marrow transplantation for acute leukemia. Finally, fusion proteins such as those combining diphtheria toxin with granulocyte-macrophage colony-stimulating factor (GM-CSF) to target the GM-CSF receptor are now being evaluated in clinical trials. Both unconjugated and conjugated antibodies have shown promise in early clinical trials, and may represent appealing therapeutic alternatives for patients with AML.     

Gemtuzumab ozogamicin (Mylotarg) in children with refractory or relapsed acute myeloid leukemia

BACKGROUND: Gemtuzumab ozogamicin (GO) is an immunoconjugate consisting of the CD33 antibody and calicheamicin, a potent cytotoxic agent. Developed for targeted treatment of CD33-positive AML, studies in adults showed its efficacy in relapsed and refractory AML. PATIENTS AND METHOD: We report 12 children with multiple relapsed or refractory AML receiving GO as compassionate use. 11 children had initially been treated according to the AML-BFM 93 or 98 protocol, 1 girl received relapse treatment (liposomal daunorubicin/FLAG) due to secondary AML. After relapse, 10 children received an intensive relapse therapy (AML-BFM 97 or international AML-Relapse Study 2001/01). 2 of them had been transplanted in first or second CR before GO therapy. RESULTS: 5 of 12 children responded to treatment with blast reduction to below 5%, but no child achieved CR after GO. Time until reoccurrence of blasts in almost all children with GO response was 3-8 months. In 5 children stem cell transplantation (SCT) was performed after GO therapy. 4 of them suffered from further progression of AML, 1 boy is in second remission with a follow-up of 8 months. 2 children had severe side effects. An anaphylactic reaction with severe hypotension was managed by catecholamine support and intensive care. In 1 girl, who relapsed after SCT in first remission, a veno-occlusive disease of the liver occurred, but could be treated successfully with defibrotide. CONCLUSION: GO therapy can induce blast reduction in children who have no further conventional treatment options. Frequency and severity of adverse events are limited, and therapy seems to be feasible for children with a sufficient general condition. Controlled studies are necessary to learn more about efficacy and side effects, especially implications for further therapy.     

CD33 as a target for selective ablation of acute myeloid leukemia

The CD33 antigen is a 67-kd glycosylated transmembrane protein of the sialic acid-binding immunoglobulinlike lectin (siglec) family with immunoreceptor tyrosine-based inhibitory motifs. It is expressed on the surface of normal mature and immature myeloid cells, including colony-forming progenitor cells, and on leukemic blasts from the majority of patients with acute myeloid leukemia (AML). CD33 is not expressed by the normal stem cells, suggesting that in vivo ablation of CD33-bearing normal and leukemic myeloid cells might lead to the establishment of normal hematopoiesis by the remaining normal stem cells. However, whether there are significant numbers of CD33- leukemic stem cells is controversial. Therapeutic trials using unmodified anti-CD33 antibodies have, thus far, met with limited success. Studies with a radiolabeled anti-CD33 antibody have demonstrated rapid saturation of, and internalization by, leukemic blast cells after intravenous administration, suggesting the possibility of using an anti-CD33 antibody to deliver a cytotoxic drug. Using gemtuzumab ozogamicin (Mylotarg, a humanized anti-CD33 antibody conjugated with calicheamicin, the effectiveness of in vivo ablation of CD33+ cells to treat patients with AML was borne out by the portion of patients who achieved remission. To what extent CD33- leukemic precursors are responsible for failure to respond or for relapse following gemtuzumab ozogamicin therapy remains to be determined.     

New developments in antibody therapy for acute myeloid leukemia

In the past three decades, improvements in the treatment of acute myeloid leukemia (AML) have increased survival in patients younger than 55 years without significant survival impact in older individuals. Unfortunately, many patients, regardless of age at diagnosis, will eventually die from their disease. Advances in the development of targeted therapies have proven beneficial in chronic myeloid leukemia and lymphoma. Gemtuzumab ozogamicin (GO; Mylotarg, Wyeth-Ayerst, St Davids, PA), a monoclonal antibody conjugated to calicheamicin, targets the CD33 antigen found on the surface of more than 80% of AML leukemic blasts. GO is approved for relapsed disease in patients older than 60 years, but is being evaluated in combination with chemotherapy, in the setting of hematopoietic stem cell transplant, and in high-risk myelodysplasia.