Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We measured the concentration of CD33 antigen on the surface of cells in 315 bone marrow (BM) samples and 114 corresponding peripheral blood (PB) samples from patients with various leukemias (acute myeloid leukemia [AML], chronic myelogenous leukemia [CML], myeloproliferative disorder [MPD] other than CML, myelodysplastic syndrome [MDS]) and from control subjects. Overall CD33 intensity in total CD33+ cells was significantly higher in BM than in PB. CD33 intensity in total BM CD33+ cells differed significantly with the type of disease. The median number of CD33 molecules per cell was highest in AML, followed by MDS, CML, and control subjects and lowest in MPD. When only CD34+/CD33+ cells were examined, CD33 molecules per cell were highest in CD34+ cells in AML and lowest in MPD (P = .027). Patients with AML or MDS younger than 60 years had significantly higher intensity of CD33 expression on CD34+ cells than patients 60 years or older. Levels of CD33 intensity did not correlate with cytogenetics in patients with AML or MDS. There was no correlation between CD33 intensity and response to therapy or overall survival in 35 patients treated with protocols including Mylotarg. These data demonstrate variation in CD33 intensity between various leukemias.
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PMID:Differences in CD33 intensity between various myeloid neoplasms. 1237 43

Significant advances in the development of monoclonal antibodies (unconjugated) and monoclonal antibodies conjugated to potent toxins or cytotoxic agents (immunoconjugates) have enabled improved targeting of leukemic cells with acceptable toxicities. Gemtuzumab ozogamicin, a calicheamicin-conjugated anti-CD33 monoclonal antibody, has demonstrated substantial efficacy in patients with acute myeloid leukemia (AML) and has induced remissions in patients with favorable-, intermediate-, and poor-risk cytogenetics. The immunoconjugate BL-22, comprised of an anti-CD22 monoclonal antibody fused to a fragment of pseudomonas exotoxin PE38, has produced high response rates in patients with purine analog-resistant hairy cell leukemia. Campath-1H (Wellcome, Beckenham, UK, and Ilex Oncology, San Antonio, TX), an anti-CD52 monoclonal antibody, has demonstrated significant activity in patients with previously untreated, relapsed, or refractory chronic lymphocytic leukemia (CLL), as well as in patients with T-cell prolymphocytic leukemia. The anti-CD20 monoclonal antibody rituximab also is effective in treating CLL and is being evaluated in combination with chemotherapeutic agents (cyclophosphamide) and fludarabine. Monoclonal antibodies may sensitize cells to chemotherapy. The optimal role of targeted therapy with monoclonal antibodies and immunoconjugates in acute and chronic leukemias has not yet been determined, but these novel therapies are beginning to fulfill their promise.
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PMID:Monoclonal antibody therapies in leukemias. 1244 47

This paper discusses background information and the body of clinical data that has been accumulated to demonstrate the efficacy and safety of gemtuzumab ozogamicin (Mylotarg, Wyeth Pharmaceuticals, Philadelphia, PA). Based on these data, gemtuzumab ozogamicin was approved by the United States Food and Drug Administration for the treatment of patients with CD33-positive acute myeloid leukemia in first relapse who are 60 years of age or older and who are not considered candidates for other cytotoxic chemotherapy. The recommended dosage of gemtuzumab ozogamicin is 9 mg/m2, administered as a 2-hour intravenous infusion for a total of 2 doses with 14 days between doses.
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PMID:Licensure of gemtuzumab ozogamicin for the treatment of selected patients 60 years of age or older with acute myeloid leukemia in first relapse. 1244 57

CD33 is a suitable target to guide delivery of a toxic moiety to most acute myeloid leukemia cells. Gemtuzumab ozogamicin (Mylotarg) is a humanized antiCD33 monoclonal antibody covalently linked to a derivative of a cytotoxic antibiotic, calicheamicin. As a single agent, gemtuzumab ozogamicin has activity (complete remission rate of 15-20%) in patients with relapsed disease. Gemtuzumab ozogamicin-based combinations are being studied as induction, maintenance and relapse regimens. The chemical hepatotoxicity often observed with gemtuzumab ozogamicin therapy is of little clinical consequence. However, hepatic veno-occlusive disease is a relatively frequent and serious toxicity for which no clear risk factors, other than stem cell transplantation, have been defined. Gemtuzumab ozogamicin-based regimens may be particularly worthy of study in patients with acute promyelocytic leukemia. Gemtuzumab ozogamicin is approved as single-agent therapy for patients over the age of 60 years in first relapse who are not considered candidates for cytotoxic therapy. The administration of gemtuzumab ozogamicin should be carried out under a level of supervision commensurate with that afforded other intensely myelosuppressive agents. Gemtuzumab ozogamicin-based combinations should not be prescribed outside the research setting until further data is available.
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PMID:Gemtuzumab ozogamicin: promise and challenge in patients with acute myeloid leukemia. 1250 9

The novel fusion protein DT(388)IL3, composed of the catalytic and translocation domains of diphtheria toxin (DT(388)) fused with a Met-His linker to human interleukin 3 (IL-3), was tested for anti-leukemia efficacy in an in vivo model of differentiated human acute myeloid leukemia (AML). Six-week-old female SCID mice were irradiated with 350 cGy, inoculated 24 h later with 20 million (i.v., i.p., or s.c.) TF1 cells transfected with the v-SRC oncogene, and treated i.p., starting 24 h later, with up to five daily injections of saline, DT(388)IL3 (2 microg), DT(388)GMCSF (2 microg), DAB(389)IL2 (2 microg), or cytarabine (80 microg) or two weekly injections of anti-CD33-calicheamicin conjugate (5 microg). Animals were monitored twice daily, and moribund animals killed and necropsied. Control animals had a median disease-free survival (DFS) of 37 days (i.v., n = 45), 35 days (i.p., n = 20), and 21 days (s.c., n = 20), respectively. Only 5/49 (10%) of the DT(388)IL3 treated i.v. inoculated animals died with leukemia. Median DFS with i.v., i.p. and s.c. tumor inoculated animals was prolonged by fusion protein treatment to >120 days, 66 days and 31 days (P < 0.001, = 0.0003, and = 0.0006), respectively. Median DFS with s.c. tumor inoculated animals was also prolonged by other active anti-leukemia agents (DT(388)GMCSF, cytarabine and anti-CD33-calicheamicin) relative to controls by 67%, 172% and 47% (P < 0.0001, <0.0001, and =0.0004), respectively. In contrast, median DFS with s.c. tumor inoculated animals treated with DAB(389)IL2 non-significantly reduced by 13% relative to controls (P = 0.21). Thus, DT(388)IL3 fusion protein demonstrates in vivo anti-leukemia efficacy and warrants further preclinical development for treatment of chemo-resistant, IL-3 receptor positive AML patients.
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PMID:Diphtheria toxin-interleukin-3 fusion protein (DT(388)IL3) prolongs disease-free survival of leukemic immunocompromised mice. 1252 73

Gemtuzumab ozogamicin (GO; Mylotarg) was developed to treat CD33(+) acute myeloid leukemia (AML). To date, only studies in adults and preliminary data from a phase 1 study in children have been reported. We report data on 15 children with relapsed/refractory CD33(+) AML who were treated with GO monotherapy on compassionate use basis (4-9 mg/m(2) up to 3 courses). Eight children showed a reduction in bone marrow blasts to 5% or less, including 5 in complete remission without full platelet recovery (CRp). Three of the 5 children with CRp received transplants almost directly following the last GO course, without awaiting further platelet regeneration. Hence in these children no clear discrimination between complete remission (CR) and CRp could be made. In 6 of 8 responding patients further treatment was given consisting of stem cell transplantation (SCT). Two patients are still alive, currently 6 and 9 months after SCT. Hematologic toxicity was difficult to assess due to subsequent SCT or leukemia. Side effects, in one patient each included veno-occlusive disease, transient grade 3 hyperbilirubinemia, transient grade 3 transaminase elevation, and grade 3 hypotension during GO administration. No infections or mucositis occurred. This report demonstrates clinical efficacy of GO in a subset of relapsed/refractory pediatric CD33(+) AML patients and suggests that intensive postremission therapy after remission induction by GO may result in durable responses in some patients, although follow-up is still short. Further studies are needed to determine the efficacy and safety of GO in children with AML.
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PMID:Gemtuzumab ozogamicin: first clinical experiences in children with relapsed/refractory acute myeloid leukemia treated on compassionate-use basis. 1254 68

Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 antibody conjugated to the anticancer agent calicheamicin, approved for the treatment of CD33+-relapsed acute myeloid leukemia. We have investigated the effects of GO on 4 human myeloid leukemia lines of different French-American-British (FAB) types (KG-1, THP-1, HL-60, and NB-4), observing 3 different types of response. Exposure to GO (10-1000 ng/mL) induced G2 arrest (up to 80% of the cells) followed by apoptosis (45% of the cells) in HL-60 and NB-4 cells. By contrast, in THP-1 cells we observed a strong G2 arrest (up to 75% of the cells) with little apoptosis. Finally, the KG-1 line was completely resistant to the same concentrations of GO. These different responses did not correlate with the levels of expression of either CD33 or multiple-drug resistance proteins, although the higher cyclosporin A (CsA)-inhibitable efflux activity of KG-1 cells may play a role in the resistance of this line to the drug. We could show that Chk1 and Chk2 phosphorylation, but not p53 or p21 expression, correlated with G2 arrest, implicating the ataxia-telangiectasia mutated/ataxia-telangiectasia related (ATM/ATR)-Chk1/Chk2 pathway in the cell cycle response to GO. However, apoptosis was associated with caspase 3 activation. Freshly isolated acute myeloid leukemia (AML) cells showed patterns of response to GO in vitro similar to those observed with the cell lines, including phosphorylation of Chk2 and caspase 3 activation. Our results suggest that the different molecular pathways induced by the drug in vitro may reflect, at least in part, the variable response to GO obtained in vivo.
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PMID:Differential response of human acute myeloid leukemia cells to gemtuzumab ozogamicin in vitro: role of Chk1 and Chk2 phosphorylation and caspase 3. 1257 28

HuM195 is a humanized, unconjugated, anti-CD33 monoclonal antibody. Fifty adult patients with relapsed or refractory AML were randomized to receive HuM195 at a dose of 12 or 36 mg/m(2) by intravenous infusion over 4 h on days 1-4 and 15-18. Patients with stable or responding disease received two additional cycles on days 29-32 and 43-46. HuM195 was given as first salvage therapy in 24 patients and as second or subsequent salvage therapy in 26 patients. Pretreatment blast percentage in the marrow was between 5 and 30% in 20 patients with the others having blast counts greater than 30%. The median age of patients was 62 years (range 26-86) and CD33 was detected in 95% of patients for whom immunophenotyping was available. Of 49 evaluable patients, two complete and one partial remission were observed. All three responses were in patients treated at the 12 mg/m(2) dose level and all had baseline blast percentages less than 30%. Decreases in blast counts ranging from 30 to 74% were seen in nine additional patients. Infusion-related events of fever and chills occurred in the majority of patients and were generally mild and primarily related to the first dose of antibody. No hepatic, renal or cardiac toxicities were observed and other adverse events such as nausea, vomiting, mucositis and diarrhea were uncommon or felt to be unrelated to HuM195. In addition, anti-HuM195 responses were not detected. HuM195 as a single agent has minimal, but observable, anti-leukemic activity in patients with relapsed or refractory AML and activity is confined to patients with low burden disease. No significant differences in clinical efficacy or toxicity were seen between the two dose levels of antibody. HuM195 was well tolerated with infusion-related fevers and chills the predominant toxicities seen. Meaningful clinical efficacy of this unconjugated monoclonal antibody may be realized only in patients with minimal residual disease, or in combination with chemotherapy.
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PMID:Treatment of relapsed or refractory acute myeloid leukemia with humanized anti-CD33 monoclonal antibody HuM195. 1259 28

The compound CMB-401 is an immunoconjugate consisting of the monoclonal antibody (MAb) hCTM01 directed against polymorphic epithelial mucin covalently bound to the cytotoxic antibiotic calicheamicin by an amide linker. We evaluated CMB-401 as monotherapy for the treatment of recurrent platinum-sensitive epithelial ovarian carcinoma (EOC). Twenty-one 21 women aged 38 to 80 years with recurrent EOC (recurrence >6 months after initial platinum-containing chemotherapy) were enrolled. Tumor response and serum cancer antigen 125 (CA125) levels were assessed before and after active treatment. After an initial intravenous (i.v.) dose of hCTM01 (without calicheamicin), the calicheamicin-linked CMB-401 (16 mg/m(2 ) i.v.) was administered over 60 min for up to 7 cycles, with 4 weeks between cycles. Nineteen patients were evaluable. Measurable changes observed following administration of CMB-401 did not meet the criteria for partial remission (PR). CMB-401 was not effective as monotherapy for this type of EOC. Adverse events experienced by patients in the study included nausea (95%), asthenia (90%), abdominal pain (62%), headache (57%), anorexia (57%), and diarrhea (57%), mostly at a toxicity grade level of 1 or 2. Based on published efficacy of conjugates that deliver calicheamicin via hybrid (bifunctional) linkers [e.g. gemtuzumab ozogamicin (Mylotarg) in acute myeloid leukemia], we hypothesize that the amide linker used in CMB-401 may have contributed to its failure to induce PR in patients in this study. Use of hybrid linkers to target hCTM01 or other antibodies to EOC may warrant further investigation.
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PMID:A phase 2 study of the cytotoxic immunoconjugate CMB-401 (hCTM01-calicheamicin) in patients with platinum-sensitive recurrent epithelial ovarian carcinoma. 1266 49

Gemtuzumab ozogamicin (GO) is a novel immunoconjugate therapy for acute myeloid leukemia (AML). P-glycoprotein (Pgp) confers resistance to GO and is associated with a worse clinical response. To address whether multidrug resistance protein (MRP) affects GO susceptibility, we characterized Pgp, MRP1, and MRP2 expression in CD33+ cell lines and CD33+ AML samples and analyzed the effect of the Pgp inhibitor cyclosporine (CSA) and the MRP inhibitor MK-571 on GO-induced cytotoxicity. MRP1, but not MRP2, expression correlated with MRP activity. MK-571 enhanced GO-induced cytotoxicity in Pgp-negative/MRP-positive NB4 and HL-60 cells. CSA, but not MK-571 alone, restored GO susceptibility in Pgp-positive/MRP-positive TF1 cells; however, MK-571 enhanced cytotoxicity in the presence of CSA. All patient samples exhibited MRP activity, and 17 of 23 exhibited Pgp activity. CSA increased GO-induced cytotoxicity in 12 Pgp-positive samples, whereas MK-571 alone was effective in only one sample with minimal Pgp activity. In 3 Pgp-positive/MRP-positive samples, MK-571 enhanced GO-induced cytotoxicity in the presence of CSA. Thus, MRP1 may attenuate susceptibility to GO. This effect was comparatively less than that for Pgp and required the inhibition of Pgp for detection in cells that coexpressed both transporters. Because MK-571 and CSA failed to affect cytotoxicity in a portion of Pgp-positive/MRP-positive AML samples, additional resistance mechanisms are likely important.
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PMID:Multidrug resistance protein attenuates gemtuzumab ozogamicin-induced cytotoxicity in acute myeloid leukemia cells. 1268 34


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