Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
Leukemia 2005 Feb
PMID:CD33-directed therapy with gemtuzumab ozogamicin in acute myeloid leukemia: progress in understanding cytotoxicity and potential mechanisms of drug resistance. 1559 33

One of the important approaches for further prolonging remission duration and eradicating minimal residual disease in acute leukemia is immunotherapy. Four kinds of immunotherapy for acute leukemia are under investigation: (1) monoclonal antibodies, among them, Mylotarg (cytotoxic antibiotic calicheamicin linked to CD33 Mab) is given for the treatment of refractory or relapsed acute myeloid leukemia and molecular relapse in acute promyelocytic leukemia with good results, Campath-1H (antiCD52 Mab) is administered in the treatment of prolymphocytic leukemia and Rituximab (anti-CD20 Mab) in B-PLL with high complete remission rates. Other Mabs under preclinical and clinical trials include anti-IL-2 receptor Mab for the treatment of acute T lymphocytic leukemia, anti-220 kD Mab-6G7 for acute leukemias, recombinant immune toxin BL22 (anti-CD22) for hairy cell leukemia and Mabs labeled with radio-isotopes for different types of acute leukemias; (2) adoptive cellular immunotherapy using cytokine-induced killer cell, alloreactive NK cells, allogeneic or autologous leukemic-specific CD8(+) cytotoxic T lymphocytes, and other immune effector cells; (3) cytokines and other immune modulators comprising IL-2, IL-12, GM-CSF, CD40L, FLT-3L and thalidomide and its derivatives; (4) leukemia vaccines of several different formulations including antigen-specific, leukemia cell-based, leukemia antigen-pulsed dendritic cell (DC) and leukemia-derived DC vaccines, the latter two formulations are more attractive. In conclusion, up to now, the most effective example of immunotherapy in acute leukemia is provided by the administration of Mabs, and the majority of other approaches in immunotherapy for acute leukemia although promising, need further studies.
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PMID:[Present status in studying immunotherapy for acute leukemia and its perspective--Editorial]. 1585 71

Since 1997, nine humanized antibodies received the approval of the FDA to be used as drugs for the treatment of various diseases including transplant rejections, metastatic breast and colon cancers, leukaemia, non-Hodgkin lymphomas, allergic conditions or multiple sclerosis. This review describes techniques used to engineer these antibodies and presents the recent evolutions of these techniques : SDRs grafting or << abbreviated >> CDRs grafting. Based on the illustrative examples of several antibodies, Mylotarg, Herceptin or Xolair, the therapeutic effectiveness of humanized antibodies are underlined and, with the example of Tysabri, the sometimes dramatic adverse effects associated with their clinical use is stressed. In a second part, this review presents some future and realistic avenues to improve the effectiveness of the humanized antibodies, to decrease their immunogenicity and to reduce their cost.
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PMID:[Humanized antibodies as therapeutics]. 1632 46

Antibodies capable to recognize antigen expressed on cancer cells represents the ideal approach for targeted anti neoplastic therapies. The CD33 antigen is present on 90% of acute myeloid leukemia blasts and is shared on normal hemopoietic cells only on the non stem dillerentiating fraction. Gemtuzumab Ozogamicin (GO) is an engineered humanized antibody anti-CD33 conjugated with a potent intercalating agent, named calicheamicin, which is release only at intracellular level (lower pH), following a selective binding to CD33-positive cells, thus representing a promising approach for target anti-leukemia therapy. GO was approved conditionally by the Federal Drug Administration in May 2000 as a single therapy for first recurrence of Acute Myeloid Leukemia (AML) in a subset of older patients. Since 2000, treatment trials and pilot studies have revealed potential expanded applications along with potential limitations. Phase II trials have confirmed the activity and the efficacy of GO as single agent in the treatment of relapsed AML. More recently, clinical trials on induction and post-remission treatment of adult AML have shown efficacy of GO in combination chemotherapy. The strong and homogeneous CD33 expression in Acute Promyelocytic Leukemia (APL), have resulted in an effective treatment of this disease with GO used as salvage treatment, as well as innovative approach for molecular relapsed patients. However, the incidence of veno-occlusive disease, better defined as sinusoidal occlusive syndrome (SOS), must be taken into account as potential complication associated with the GO administration, especially in patients treated with ablative regimens. In conclusion, the extension of the approval in Italy to AML CD33+ in relapsed, regardless age limitation, along with the ongoing evaluation by the European EMEA, represent the basis for a large clinical application of GO in myeloid malignancies potentially extended to paediatric patients with AML and to ALL CD33+.
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PMID:[Therapeutic advances in neoplastic hematology: target therapy anti-CD33]. 1634 20

Gemtuzumab ozogamicin (GO) is an immunoconjugate that binds to CD33 on the surface of acute myeloid leukaemia (AML) blasts and, after internalisation, releases a cytotoxic drug, calicheamicin. GO is approved by the US Food and Drug Administration for the treatment of CD33-positive AML at first relapse in patients 60 years and older who are not candidates for other cytotoxic therapy. GO as a single agent has low antileukaemic activity. When given to patients meeting the criteria noted above, it produces a complete response (CR) rate of only 12%, with another 12% achieving CR with inadequate platelet recovery (CRp). The median survival of patients treated with GO monotherapy is 11.2 months. GO therapy at 9 mg/m(2) is complicated with hepatic veno-occlusive disease in 5-10% of patients, particularly prior to or following stem cell transplantation. GO at lower doses combined with chemotherapy as induction or postremission therapy is promising, however, and phase III trials are ongoing. GO is probably most active in acute promyelocytic leukaemia (APL). It is used for induction regimens in high-risk APL and for the elimination of minimal residual APL. Case reports suggest that GO also has activity in CD33-positive acute lymphoblastic leukaemia. In conclusion, single agent GO can induce responses in patients with CD33-positive AML in first recurrence. The future of GO is its use in combination with other cytotoxic agents. Ongoing clinical trials may better define the role of GO combinations, particularly in untreated AML.
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PMID:The role of gemtuzumab ozogamicin in acute leukaemia therapy. 1641 15

In recent decades rapid improvements in the results of treatment of adult acute lymphoblastic leukaemia (ALL) have been achieved. This progress has been based mainly on intensification and optimization of chemotherapy, risk-adapted use of stem-cell transplantation, and improved supportive care. However, results in adult patients are still considerably inferior to those in paediatric ALL, and a barrier to further intensification of chemotherapy appears to have been reached regarding toxicity. More recently, the most significant progress has therefore been achieved by individualized and targeted therapy - for example, treatment with monoclonal antibodies (MoAbs). ALL blast cells express a variety of specific antigens which may serve as targets: e.g. CD19, CD20, CD22, CD33, and CD52. Most experience is available for anti-CD20 (rituximab). In ALL, rituximab is combined with chemotherapy mainly in mature B-ALL and Burkitt's lymphoma, and interim results are very promising. Recently studies with rituximab have also been initiated in B-precursor ALL. Other antibodies would be of interest due to a high rate of antigen (e.g. CD19) expression in ALL, but these are not yet generally available. Clinical application in smaller studies or case reports was reported for anti-CD52 and anti-CD33. Overall it can be stated that MoAb therapy in ALL is a promising treatment approach. Monotherapy with MoAbs in relapsed ALL has also occasionally achieved responses, but greater effects can be expected from combination with chemotherapy and treatment in the state of minimal residual disease. Details of these regimens - required level of antigen expression, timing, schedule, dosage and stage of disease - remain to be defined.
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PMID:Novel antibody-based therapy for acute lymphoblastic leukaemia. 1699 78

Acute myeloid leukemia (AML) cells express the cell surface antigen CD33 that, upon ligation with a monoclonal antibody (mAb), is a downregulator of cell growth in a Syk-dependent manner. An anti-CD33 mAb coupled to a toxin, gemtuzumab ozogamicin (GO), is used for the treatment of AML (Mylotarg). Therefore, we investigated whether the response of AML cells to GO treatment also depends on Syk expression. Forty primary AML samples (25 Syk-positive and 15 Syk-negative) were tested for their response to the anti-proliferative effects of GO and unmodified anti-CD33 mAb. A correlation between Syk expression and the response of leukemia cells to GO and anti-CD33 mAb was found. 'Blocking' of Syk by small interfering RNA resulted in unresponsiveness of AML cells to both GO and anti-CD33 mAb-mediated cytotoxicity. Syk upregulation by the de-methylating agent 5-azacytidine (5-aza) induced re-expression of Syk in some cases, resulting in enhanced GO and anti-CD33-mediated inhibition of leukemia cell growth. Thus, the cytotoxicity of both GO and anti-CD33 in primary AML samples was associated with Syk expression. 5-Aza restored Syk and increased the sensitivity of originally Syk-negative, non-responsive cells to CD33 ligation to levels of Syk-positive cells. These data have clinical significance for predicting response to GO and designing clinical trials.
Leukemia 2006 Dec
PMID:Cytotoxic activity of gemtuzumab ozogamicin (Mylotarg) in acute myeloid leukemia correlates with the expression of protein kinase Syk. 1705 Dec 43

Pivotal phase II studies in acute myeloblastic leukemia (AML) patients in first relapse have used gemtuzumab ozogamicin (GO) (Mylotarg) at a dose of 9 mg/m(2) on days 1 and 14. These studies showed a 26% response rate (13% complete remission (CR) and 13% CRp (complete remission with incomplete platelet recovery)) but with high degree of hematological and liver toxicities. Based on in vitro studies showing a re-expression of CD33 antigenic sites on the cell surface of blasts cells after exposure to GO, we hypothesized that fractionated doses of GO may be efficient and better tolerated. Fifty-seven patients with AML in first relapse received GO at a dose of 3 mg/m(2) on days 1, 4 and 7 for one course. Fifteen patients (26%) achieved CR and four (7%) CRp. Remission rate correlated strongly with P-glycoprotein and MRP1 activities. The median relapse-free survival was 11 months, similar for CR or CRp patients. Median duration of neutropenia < 500/microl and thrombocytopenia < 50,000/microl were, respectively, 23 and 21 days. No grade 3 or 4 liver toxicity was observed. No veno-occlusive disease occurred after GO or after hematopoietic stem cell transplantation given after GO in seven patients. Mylotarg administered in fractionated doses demonstrated an excellent efficacy/safety profile.
Leukemia 2007 Jan
PMID:High efficacy and safety profile of fractionated doses of Mylotarg as induction therapy in patients with relapsed acute myeloblastic leukemia: a prospective study of the alfa group. 1705 Dec 46

Gemtuzumab ozogamicin (GO) is a calicheamicin-conjugated antibody directed against CD33, an antigen highly expressed on acute myeloid leukemic (AML) cells. CD33-specific binding triggers internalization of GO and subsequent hydrolytic release of calicheamicin. Calicheamicin then translocates to the nucleus, intercalates in the DNA structure and subsequently induces double-strand DNA breaks. GO is part of clinical practice for AML, but is frequently associated with severe side effects. Therefore, combination of GO with other therapeutics is warranted to reduce toxicity, while maximizing therapeutic selectivity. We hypothesized that the histone deacetylase inhibitor valproic acid (VPA) sensitizes AML cells to GO. VPA-induced histone hyperacetylation opens the chromatin structure, whereby the DNA intercalation of calicheamicin should be augmented. We found that clinically relevant concentrations of VPA potently augmented the tumoricidal activity of GO towards AML cell lines and primary AML blasts. Moreover, VPA treatment indeed augmented the DNA intercalation of calicheamicin and enhanced DNA degradation. Importantly, synergy was restricted to CD33-positive AML cells and did not require caspase activation. In conclusion, the synergistic proapoptotic activity of cotreatment of AML cells with VPA and GO indicates the potential value of this strategy for AML.
Leukemia 2007 Feb
PMID:The histone deacetylase inhibitor valproic acid potently augments gemtuzumab ozogamicin-induced apoptosis in acute myeloid leukemic cells. 1712 63

The same progress in the recent therapeutic strategy for older adults with hematological malignancies has also been seen in younger adults. The standard initial therapy for elderly acute promylocytic leukemia is the combination with all-trans retinoic acid and anthracyclines. For other acute myeloid leukemias (AML), many trials of combination chemotherapy have not improved the outcome of elderly patients. Gemtuzumab ozogamicin,which is an immunoconjugate binding to CD 33 on the surface of AML blasts, has produced good results for elderly patients in either monotherapy or in combination with conventional chemotherapeutic drugs. One of the BCR-ABL tyrosine kinase inhibitors, imatinib mesylate, is active for elderly Philadelphia-positive leukemia including acute lymphoblastic leukemia and chronic myeloid leukemia. In the treatment of elderly diffuse large B cell lymphoma, combination of rituximab and cyclophosphamide+doxorubicin+vincristine+prednisone (CHOP) has become the therapy of choice based upon a Groupe d'Etude des Lymphomes de l'Adulte (GELA) trial even though there are some other trials for elderly patients such as dose-dense CHOP therapy. For follicular lymphoma, combination therapies of rituximab and cytotoxic drugs such as R-CHOP and R-CVP are also considered as promising therapies. For the management of multiple myeloma, high-dose chemotherapy, mainly melphalan with autologous stem cell transplantation, has become the standard treatment even for elderly patients less than 65 years of age.
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PMID:[Hematological malignancies]. 1735 25


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