sdz-psc-833 and Leukemia--Myeloid

P-glycoprotein (Pgp) expression is an independent prognostic factor for response to remission-induction chemotherapy in acute myeloblastic leukaemia, particularly in the elderly. There are several potential agents for modulating Pgp-mediated multi-drug resistance, such as cyclosporin A and PSC833, which are currently being evaluated in clinical trials. An alternative therapeutic strategy is to increase the use of drugs which are unaffected by Pgp. However, in this review, we explain why this may be more difficult than it appears. Evidence from in vitro studies of primary AML blasts supports the commonly held supposition that chemoresistance may be linked to apoptosis-resistance. We have found that Pgp has a drug-independent role in the inhibition of in vitro apoptosis in AML blasts. Modulation of cytokine efflux, signalling lipids and intracellular pH have all been suggested as ways by which Pgp may affect cellular resistance to apoptosis; these are discussed in this review. For a chemosensitising agent to be successful, it may be more important for it to enhance apoptosis than to increase drug uptake.

Topics: Acute Disease; Adult; Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Cell Division; Ceramides; Child; Cyclosporine; Cyclosporins; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Enzyme Inhibitors; Humans; Hydrogen-Ion Concentration; Leukemia, Myeloid; Lovastatin; Multicenter Studies as Topic; Neoplasm Proteins; Oxides; Phenotype; Protein Kinase C; Randomized Controlled Trials as Topic; Signal Transduction; Tumor Cells, Cultured

Resistance to natural product-derived anti-cancer drugs, such as the anthracyclines and etoposide, contributes to the failure of chemotherapeutic treatment of leukaemia. One biological resistance mechanism of potential importance is the overexpression of the plasma membrane drug transporter proteins P-glycoprotein (Pgp) and multidrug resistance protein (MRP). Many studies have reported evidence for a correlation of Pgp/MDR1 expression with unfavourable prognostic features in acute myeloid leukaemia (AML). Failure to achieve complete remission (CR) is correlated with Pgp and the CD34+ phenotype. For MRP fewer data are available, which suggest a basal expression level in most AMLs. Another protein reported to correlate with treatment failure in AML is the lung resistance protein or major vault protein (LRP), a protein with a still unknown function. Co-expression of Pgp and LRP especially seems to define an adverse prognostic population. Further progress towards the understanding of the clinical importance of these proteins is hampered by the lack of validation of methods to determine their expression. A reliable way to measure Pgp seems to be the assessment of the active transport of fluorescent Pgp substrates, such as rhodamine 123 out of AML cells. Such functional Pgp assays can be used to validate mRNA or protein measurements and to quantify the effect of Pgp or the magnitude of the effect of a blocker of the Pgp-mediated drug efflux on the intracellular drug concentration. The prognostic value of such methods has still to be shown.

Topics: Acute Disease; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP-Binding Cassette Transporters; Cyclosporins; Drug Resistance, Multiple; Gene Expression Regulation, Neoplastic; Humans; Leukemia, Myeloid; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Prognosis; Ribonucleoproteins; Vault Ribonucleoprotein Particles

P-glycoprotein (Pgp) is strongly inhibited by PSC-833. A chemotherapy dose-escalation study was performed with PSC-833 in patients younger than 60 years with untreated acute myeloid leukemia. Clinical rather than pharmacokinetic end points were used to develop two induction therapies containing drugs susceptible to Pgp-mediated efflux and associated with comparable toxicities at the maximum-tolerated doses.. A total of 410 patients were enrolled. Fifteen induction regimens containing variable doses of daunorubicin (DNR) and etoposide (ETOP) and fixed doses of cytarabine were evaluated with (ADEP) or without (ADE) a fixed dose of PSC-833.. Doses selected for phase III testing were DNR 90 mg/m(2) and ETOP 100 mg/m(2) in ADE, and DNR and ETOP each 40 mg/m(2) in ADEP. Intolerable mucosal toxicity occurred at higher doses of ADEP. Although the design of this study precludes direct comparisons, there was an apparent advantage for receiving ADEP with respect to disease-free and overall survival in patients < or = 45 years old, despite the significantly lower doses of DNR and ETOP given in ADEP compared with ADE.. A large clinical data set was used to develop induction regimens containing two drugs susceptible to Pgp-mediated efflux, with and without an inhibitor of Pgp function. The chosen doses have comparable antileukemia activity and toxicity, making them suitable for use in a phase III comparative study of induction chemotherapy for patients with acute myeloid leukemia younger than 60 years. That trial will also clarify whether patients < or = 45 years old are especially likely to benefit from Pgp inhibition during induction therapy.

Topics: Acute Disease; Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; Cyclosporins; Cytarabine; Daunorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Etoposide; Female; Humans; Leukemia, Myeloid; Logistic Models; Male; Middle Aged; Survival Analysis; Treatment Outcome

The cyclosporine analog Valspodar (PSC 833, Novartis Pharma) is a strong inhibitor of the mdr1 gene product p-glycoprotein (pgp). A phase I/II study was conducted in order to evaluate if addition of Valspodar to treatment with daunorubicin and cytarabine, given to patients with primary refractory or relapsed acute myeloid leukemia, could increase the complete remission rate.Fifty-three patients were treated in cohorts of three to six patients. Twelve patients reached a complete remission in bone marrow, five of whom also normalized their peripheral blood values. Three patients experienced treatment-related deaths from pneumonia, liver failure and cerebral hemorrhage, respectively. It is concluded that Valspodar 10 mg/kg per 24 h in combination with daunorubicin 45 mg/m(2) for 3 days and cytarabine 1 g/m(2) twice daily for 4 days is tolerable in this heavily pre-treated group of patients. Due to the moderate treatment results, the phase II part of the study was ended prematurely. The modulation of only pgp did not give an obvious improvement of the treatment results in this group of patients.

Topics: Acute Disease; Adolescent; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cause of Death; Cyclosporins; Cytarabine; Daunorubicin; Dose-Response Relationship, Drug; Drug Resistance, Multiple; Humans; Leukemia, Myeloid; Middle Aged; Remission Induction; Salvage Therapy; Treatment Outcome

The purpose of the study is to investigate the tolerability of interleukin 2 (IL-2) after intensive chemotherapy in elderly acute myeloid leukemia (AML) patients in first complete remission (CR).. AML patients > or =60 years in CR after induction and consolidation chemotherapy on Cancer and Leukemia Group B study 9420 were eligible if they had neutrophils > or =1 x 10(9)/liters and platelets > or =75 x 10(9)/liters. Patients received low-dose IL-2 (1 x 10(6) IU/m(2)/day s.c. for 90 days) or low-dose IL-2 with intermediate pulse doses (6-12 x 10(6) IU/m(2)/day s.c. for 3 days) every 14 days (maximum five pulses). In a subset of patients, we investigated the expression of NKG2D ligands by leukemic cells because they are likely important mediators of natural killer cytotoxicity.. Of 35 CR patients receiving IL-2, 34 were evaluable for toxicity. Median age was 67 (range, 60-76) years. Thirteen of 16 patients receiving low-dose IL-2 completed the planned therapy, and 11 of 18 who also received intermediate pulse dose IL-2 therapy completed all five pulses. The spectrum of toxicity in both groups was similar, with predominantly grade 1-2 fatigue, fever, injection site reactions, nausea, anemia, and thrombocytopenia. Grade 3-4 hematological and nonhematological toxicity were more frequent in patients also receiving intermediate pulse dose IL-2 therapy. Grade 3-4 fatigue and hematological toxicity, although uncommon, were the major causes for discontinuing or attenuating therapy. In 8 cases, mRNA for one or more NKG2D ligands was detected in leukemic cells obtained at diagnosis before treatment.. Low-dose IL-2, with or without intermediate pulse dose therapy, given immediately after chemotherapy in first CR to elderly AML patients is well tolerated. Expression of NKG2D ligands by leukemic cells was detected in the majority of cases tested and should be assessed for correlation with response to IL-2 in future studies.

Topics: Acute Disease; Age Factors; Aged; Antineoplastic Combined Chemotherapy Protocols; Combined Modality Therapy; Cyclosporins; Cytarabine; Daunorubicin; Disease-Free Survival; Drug Administration Schedule; Etoposide; Fatigue; Gene Expression Regulation, Neoplastic; Hematologic Diseases; Humans; Immunologic Factors; Interleukin-2; Killer Cells, Natural; Leukemia, Myeloid; Life Tables; Middle Aged; Nausea; Neoplasm Proteins; NK Cell Lectin-Like Receptor Subfamily K; Receptors, Immunologic; Receptors, Natural Killer Cell; Recombinant Fusion Proteins; Remission Induction; Survival Analysis; Treatment Outcome

To determine the maximum-tolerated dose, pharmacokinetic interaction, and activity of PSC 833 compared with daunorubicin (DNR) and cytarabine in patients with poor-risk acute myeloid leukemia.. Patients received ara-C 3 g/m(2)/d on 5 consecutive days, followed by an IV loading dose of PSC 833 (1.5 mg/kg) and an 84-hour continuous infusion escalating from 6, 9, or 10 mg/kg/d. Daunorubicin was administered as a 72-hour continuous infusion at 34 or 45 mg/m2/d [corrected]. Responding patients received consolidation chemotherapy with DNR pharmacokinetics performed without PSC-833 on day 1, and with PSC-833 on day 4. Response was correlated with expression of P-glycoprotein and lung resistance protein (LRP), and in vitro sensitization of leukemia progenitors to DNR cytotoxicity by PSC 833.. All 43 patients are assessable for toxicity and response. Grade 3 or greater hyperbilirubinemia (70%) was the only dose-dependent toxicity. Four patients (9%) succumbed to treatment-related complications. Twenty-one patients (49%) achieved a complete remission or restored chronic phase, including 10 of 20 patients treated at the maximum-tolerated dose of 10 mg/kg/d of PSC-833 and 45 mg/m(2) of DNR. The 95% confidence interval for complete response was 33.9% to 63.7%. Administration of PSC 833 did not alter the mean area under the curve for DNR, although clearance decreased approximately two-fold (P =.04). Daunorubicinol clearance decreased 3.3-fold (P =.016). Remission rates were not effected by mdr-1 expression, but LRP overexpression was associated with chemotherapy resistance.. Combined treatment with infused PSC 833 and DNR is well tolerated and has activity in patients with poor risk acute myeloid leukemia. Administration of PSC 833 delays elimination of daunorubicinol, but yields variable changes in DNR systemic exposure.

Topics: Acute Disease; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; Cyclosporins; Cytarabine; Daunorubicin; Dose-Response Relationship, Drug; Drug Interactions; Female; Humans; Infusions, Intravenous; Leukemia, Myeloid; Male; Middle Aged; Risk Factors; Treatment Outcome

Older patients with acute myelogenous leukemia (AML) have overexpression of P-glycoprotein (Pgp+), and this has been shown to correlate quantitatively with therapeutic outcome. Since Pgp-mediated efflux of cytotoxic drugs can be inhibited by the cyclosporine analogue, PSC 833, we investigated the use of this agent with a 5-day mitoxantrone/etoposide regimen in patients over age 55 with newly diagnosed AML. Previous studies suggested a 33% incidence of grade IV/V non-hematologic toxicity with the use of mitoxantrone 10 mg/M(2) and etoposide 100 mg/M(2), each for 5 days, in this patient population. Since PSC 833 alters the pharmacokinetic excretion of MDR-related cytotoxins, this phase I dose-finding study was performed to identify doses of mitoxantrone/etoposide associated with a similar 33% incidence of grade IV/V non-hematologic toxicity, when given with PSC 833. Mitoxantrone/etoposide (M/E) doses were escalated in fixed ratio from a starting dose of M: 4 mg/M(2) and E: 40 mg/M(2), to M: 7 mg/M(2) and E: 70 mg/M(2), in successive cohorts of eight patients each. PSC 833 was well tolerated and the MTD of this M/E regimen with PSC 833 in this population was M: 6 mg/M(2) and E: 60 mg/M(2). The complete response (CR) rate for all patients was 50% (15/30) and was considerably higher for de novo than for secondary AML. These data suggest that the addition of PSC 833 to an M/E regimen for older patients with untreated AML is well tolerated but requires a reduction in M/E dosing to avoid increased toxicity.

Topics: Acute Disease; Aged; Antineoplastic Combined Chemotherapy Protocols; Cyclosporins; Disease-Free Survival; Etoposide; Female; Humans; Leukemia, Myeloid; Male; Middle Aged; Mitoxantrone; Survival Analysis; Treatment Outcome

This trial was designed to determine the maximum tolerated dose of intravenous daunorubicin (DNR) in combination with valspodar and to test the feasibility of P-glycoprotein modulation using valspodar in elderly patients with previously untreated acute myelogenous leukemia receiving standard induction chemotherapy.. Patients > or =60 years of age with previously untreated AML received valspodar (10 mg/kg/24 h by continuous intravenous infusion [CIV] on days 1-4 with a 2-mg/kg loading dose on day 1) in conjunction with two cycles of induction chemotherapy consisting of cytarabine (200 mg/m(2) CIV on days 1-7), and DNR (35 mg/m(2) [cohort 1] or 45 mg/m(2) [cohort 2] on days 1-3, intravenous bolus). Patients were assessed for dose-limiting toxicities (DLT), response rate, event-free and overall survival, and pharmacokinetics of valspodar and DNR.. Valspodar was well tolerated at the lower DNR dose level (ie, 35 mg/m(2)) resulting in a 21% rate of DLT and only three toxic deaths. Treatment-related mortality was unacceptably high at the 45 mg/m(2) DNR dose level. The complete response rate was 49% overall and similar in both cohorts. The median overall survival of patients was 333 days in cohort 1 compared to 98 days in cohort 2. At baseline, 70% of assessable patients were P-glycoprotein positive.. Substantial inhibition of P-glycoprotein activity can be achieved in this patient population at clinically tolerable doses of valspodar and DNR. The maximum tolerated dose of DNR was established as 35 mg/m(2). This regimen is being further evaluated in phase III trials.

Topics: Acute Disease; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cohort Studies; Cyclosporins; Cytarabine; Daunorubicin; Dose-Response Relationship, Drug; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Edema; Female; Fever; Humans; Hypokalemia; Leukemia, Myeloid; Male; Maximum Tolerated Dose; Middle Aged; Nausea; Neoplasm Proteins; Remission Induction; Survival Analysis; Survival Rate; Treatment Outcome

A potential mechanism of chemotherapy resistance in acute myeloid leukemia (AML) is the multidrug resistance (MDR-1) gene product P-glycoprotein (P-gp), which is often overexpressed in myeloblasts from refractory or relapsed AML. In a multicenter phase II clinical trial, 37 patients with these poor risk forms of AML were treated with PSC 833 (Valspodar; Novartis Pharmaceutical Corporation, East Hanover, NJ), a potent inhibitor of the MDR-1 efflux pump, plus mitoxantrone, etoposide, and cytarabine (PSC-MEC). Pharmacokinetic (PK) interactions of etoposide and mitoxantrone with PSC were anticipated, measured in comparison with historical controls without PSC, and showed a 57% decrease in etoposide clearance (P =.001) and a 1.8-fold longer beta half-life for mitoxantrone in plasma (P <.05). The doses of mitoxantrone and etoposide were substantially reduced to compensate for these interactions and clinical toxicity and in Cohort II were well tolerated at dose levels of 4 mg/m2 mitoxantrone, 40 mg/m2 etoposide, and 1 g/m2 C daily for 5 days. Overall, postchemotherapy marrow hypoplasia was achieved in 33 patients. Twelve patients (32%) achieved complete remission, four achieved partial remission, and 21 failed therapy. The PK observations correlated with enhanced toxicity. The probability of an infectious early death was 36% (4 of 11) in patients with high PK parameters for either drug versus 5% (1 of 20) in those with lower PK parameters (P =.04). P-gp function was assessed in 19 patients using rhodamine-123 efflux and its inhibition by PSC. The median percentage of blasts expressing P-gp was increased (49%) for leukemic cells with PSC-inhibitable rhodamine efflux compared with 17% in cases lacking PSC-inhibitable efflux (P =.004). PSC-MEC was relatively well tolerated in these patients with poor-risk AML, and had encouraging antileukemic effects. The Eastern Cooperative Oncology Group is currently testing this regimen versus standard MEC chemotherapy in a phase III trial, E2995, in a similar patient population.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; ATP Binding Cassette Transporter, Subfamily B, Member 1; Bone Marrow; Cardiovascular Diseases; Cohort Studies; Cyclosporins; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Etoposide; Female; Filgrastim; Granulocyte Colony-Stimulating Factor; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Infections; Leukemia, Myeloid; Male; Middle Aged; Mitoxantrone; Neoplasm Proteins; Recombinant Proteins; Remission Induction; Treatment Outcome

The Cancer and Leukemia Group B conducted parallel phase I trials of cytarabine, daunorubicin, and etoposide (ADE) with or without PSC-833 (P), a modulator of p-glycoprotein-mediated multidrug resistance.. One hundred ten newly diagnosed patients > or = 60 years of age with de novo acute myeloid leukemia (AML) were treated. All patients received cytarabine by continuous infusion for 7 days at 100 mg/m(2)/d. The starting dose of daunorubicin was 30 mg/m(2)/d for 3 days. Etoposide was administered at a dose of 100 mg/m(2)/d for 3 days, except in the last cohort administered ADEP, who received 60 mg/m(2). PSC-833 was given intravenously with a loading dose of 1.5 mg/kg over 2 hours and a simultaneous continuous infusion of 10 mg/kg/d continued until 24 hours after the last dose of daunorubicin or etoposide.. There was no toxicity attributed to the PSC-833. Dose-limiting toxicity was primarily gastrointestinal (diarrhea, mucositis in the ADEP group). The estimated maximum-tolerated doses, calculated using a logistic regression model, were daunorubicin 40 mg/m(2)/d for 3 days with etoposide 60 mg/m(2) for 3 days in the ADEP group and daunorubicin 60 mg/m(2)/d for 3 days and etoposide 100 mg/m(2)/d for 3 days in the ADE group. Twenty-one (48%) of 44 patients achieved complete remission with ADE, compared with 29 (44%) of 66 patients treated with ADEP.. It is necessary to decrease the doses of daunorubicin and etoposide when they are administered with PSC-833, presumably because of the effect of the modulator on the pharmacokinetics of these agents. A phase III trial comparing the regimens derived from this phase I trial has recently begun.

Topics: Acute Disease; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Cyclosporins; Cytarabine; Daunorubicin; Drug Resistance, Neoplasm; Etoposide; Female; Humans; Leukemia, Myeloid; Male; Middle Aged

Diagnostic cytogenetic abnormalities are considered important prognostic factors in patients with acute myeloid leukaemia (AML). However, the prognostic assessments have mainly been derived from patients with AML aged <60 years. Two recent studies of AML patients of 60 years and older proposed prognostic classifications with distinct discrepancies. To further study the prognostic value of cytogenetic abnormalities in this patient population, we have evaluated cytogenetic abnormalities in a series of 293 untreated patients with AML aged 60 years and older, included in a randomised phase 3 trial, also in relation to patient characteristics and clinical outcome. The most frequently observed cytogenetic abnormality was trisomy 8 (+8), in 31 (11%) patients. Abnormalities, such as -5, 5q-, abn(17p) and abn(17q), were almost exclusively present in complex karyotypes. A relatively favourable outcome was only observed in five patients with core-binding factor abnormalities t(8;21) and inv(16)/del(16)/t(16;16). However, most of the other evaluated cytogenetic abnormalities, such as 5q-, -7, +8, abn(17p), abn(17q), and complex aberrations expressed a more adverse prognosis when compared with patients with AML aged 60 years and older with a normal karyotype. Large studies to confirm the prognosis of individual cytogenetic aberrations are warranted.

Topics: Acute Disease; Aged; Antineoplastic Combined Chemotherapy Protocols; ATP Binding Cassette Transporter, Subfamily B, Member 1; Chromosome Aberrations; Cyclosporins; Disease-Free Survival; Female; Genes, MDR; Humans; Immunosuppressive Agents; In Situ Hybridization, Fluorescence; Leukemia, Myeloid; Leukocyte Count; Male; Middle Aged; Prognosis; Prospective Studies; Survival Analysis; Treatment Outcome

The ability of acute myeloid leukaemia (AML) blasts to survive in culture has been associated with poor patient response to chemotherapy. Other biological factors predicting an adverse outcome include p-glycoprotein (pgp) expression, which is associated with a reduced remission rate, and the presence of fms-like tyrosine kinase 3 gene (FLT3) internal tandem duplications (ITDs), predictive of a high rate of leukaemic relapse. Our previous work has indicated a drug efflux-independent role for pgp in apoptosis resistance. We measured spontaneous in vitro apoptosis in 58 primary AML samples to establish its relationship with functional and phenotypic pgp and with FLT3 ITDs. Cells were incubated for 48 h in a suspension culture, and the remaining viable cells were counted by flow cytometry. Median survival was 38% of baseline values. Resistance to spontaneous apoptosis was strongly associated with pgp (MRK-16 antibody) expression (P = 0.001) and with pgp functional activity (P < 0.001). FLT3 ITDs, found in 20 cases, were inversely associated with functional pgp activity: thus, the median pgp modulation ratio was 2.0 in FLT3 wild-type cases and 1.38 in ITD cases (P = 0.018). Also, the presence of FLT3 ITDs was not associated with in vitro apoptosis resistance. In conclusion, we have found that the presence of FLT3 ITDs is not related to AML blast survival in vitro, and is inversely associated with pgp activity, whereas pgp expression and activity are associated with resistance to spontaneous apoptosis. These results may help to explain the differing adverse effects of pgp (on remission induction) and FLT3 ITDs (on relapse) in AML.

Topics: Acute Disease; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cyclosporins; Drug Resistance, Multiple; Flow Cytometry; Fluorescent Dyes; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid; Proto-Oncogene Proteins; Receptor Protein-Tyrosine Kinases; Recurrence; Remission Induction; Repetitive Sequences, Nucleic Acid; Rhodamine 123; Statistics, Nonparametric; Tumor Cells, Cultured

Gemtuzumab ozogamicin (CMA-676), a calicheamicin-conjugated humanized anti-CD33 mouse monoclonal antibody, has recently been introduced clinically as a promising drug for the treatment of patients with acute myeloid leukemia (AML), more than 90% of which express CD33 antigen. However, our recent study suggested that CMA-676 was excreted by a multi- drug-resistance (MDR) mechanism in P-glycoprotein (P-gp)-expressing leukemia cell lines. We analyzed the in vitro effects of CMA-676 on leukemia cells from 27 AML patients in relation to the amount of P-gp, MDR-associated protein 1 (MRP1), CD33 and CD34, using a multi-laser-equipped flow cytometer. The cytocidal effect of CMA-676, estimated by the amount of hypodiploid portion on cell cycle, was inversely related to the amount of P-gp estimated by MRK16 monoclonal antibody (P = 0.004), and to the P-gp function assessed by intracellular rhodamine-123 accumulation in the presence of PSC833 or MS209 as a MDR modifier (P = 0.0004 and P = 0.002, respectively). In addition, these MDR modifiers reversed CMA-676 resistance in P-gp-expressing CD33(+) leukemia cells (P = 0.001 with PSC833 and P = 0.0007 with MS209). In CD33(+) AML cells from 13 patients, CMA-676 was less effective on CD33(+)CD34(+) than CD33(+)CD34(-) cells (P = 0.002). PSC833 partially restored the effect of CMA-676 in CD33(+)CD34(+) cells. These results suggest that the combined use of CMA-676 and a MDR modifier will be more effective on CD33(+) AML with P-gp-related MDR.

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Aminoglycosides; Anti-Bacterial Agents; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antigens, CD; Antigens, CD34; Antigens, Differentiation, Myelomonocytic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Cycle; Cyclosporins; Drug Interactions; Drug Resistance, Neoplasm; Female; Gemtuzumab; Humans; Immunotoxins; Leukemia, Myeloid; Male; Middle Aged; Quinolines; Sialic Acid Binding Ig-like Lectin 3; Tumor Cells, Cultured

Multidrug resistance (MDR) to cancer chemotherapy is frequently associated with decreased drug accumulation in cancer cells due to drug expulsion by multidrug transporters such as P-glycoprotein (Pgp) and multidrug resistance protein (MRP). The novel resistance modifying agents PSC 833, 280-446, and LY 335979 are primarily targeted at inhibition of Pgp, and their MRP inhibitory potential is largely unknown.. In the present study we addressed the effect of these agents on MRP-derived drug resistance.. Drug-resistant human leukemia cells with Pgp+/MRP- (KG1a/200, K562/150) and Pgp-/MRP+ (HL60/130) phenotypes were maintained in suspension cultures for experimental studies of drug accumulation and drug sensitization by Pgp inhibitors.. Intracellular accumulation of the fluorescent anthracycline daunorubicin was measured by flow cytometry and fluorescence detection. Daunorubicin dose-response curves were generated by non-linear regression of electronically measured cell counts of 72- - 96-h cultures. The half-maximal growth inhibitory dose (GI50) was used as measure of growth inhibition.. All MDR phenotypes studied exercised significant resistance to daunorubicin. PSC 833, 280-446 and LY335979 were equal in sensitizing Pgp+/MRP- cells to daunorubicin-induced growth inhibition (p < 0.0001). The Pgp-/MRP+ cells responded to PSC 833 and 280-446 by increased accumulation of daunorubicin (p = 0.0022 and p = 0.0005, respectively) and sensitization to the drug (p = 0.0009 and p = 0.0007, respectively). Conversely, LY335979 did not affect accumulation of daunorubicin in Pgp-/MRP+ cells nor sensitize these cells to daunorubicin.. Pgp inhibitory agents have differential effects on MRP-derived drug resistance which could be exploited in treatment of multidrug resistance in cancer patients.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B; Cyclosporins; Daunorubicin; Dibenzocycloheptenes; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flow Cytometry; Fluorescence; Humans; Leukemia, Myeloid; Peptides, Cyclic; Quinolines; Tumor Cells, Cultured

Despite treatment with intensive chemotherapy, a considerable number of patients with acute myeloid leukemia (AML) die from their disease due to the occurrence of resistance. Overexpression of the transporter proteins P-glycoprotein (P-gp) and multidrug resistance protein (MRP) 1 has been identified as a major cause of cross-resistance to functionally and structurally unrelated drugs. In the present study, the functional activity of P-gp and MRP was determined in 104 de novo AML patients with a flow cytometric assay using rhodamine 123 (Rh123) in combination with PSC833 and carboxyfluorescein (CF) in combination with MK-571. The results were compared with clinical outcome and with known prognostic factors. The functional activity of P-gp and MRP, expressed as Rh123 efflux blocking by PSC833 and CF efflux blocking by MK-571, demonstrated a great variability in the AML patients. A strong negative correlation was observed between Rh123 efflux blocking by PSC833 and Rh123 accumulation (r(s) = -0.69, P < 0.001) and between CF efflux blocking by MK-571 and CF accumulation (r(s) = -0.59, P < 0.001). A low Rh123 accumulation and a high Rh123 efflux blocking by PSC833 were associated with a low complete remission (CR) rate after the first cycle of chemotherapy (P = 0.008 and P = 0.01, respectively). Patients with both low Rh123 and CF accumulation (n = 16) had the lowest CR rate (6%), whereas patients with both high Rh123 and CF accumulation (n = 11) had a CR rate of 73%. AML patients with French-American-British classification M1 or M2 showed a lower Rh123 accumulation than patients with French-American-British classification M4 or M5 (P = 0.02). No association was observed between the multidrug resistance parameters and overall survival of the AML patients. Risk group was the only predictive parameter for overall survival (P = 0.003).

Topics: Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP-Binding Cassette Transporters; Cyclosporins; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Flow Cytometry; Fluoresceins; Fluorescent Dyes; Glutathione; Humans; Leukemia, Myeloid; Male; Middle Aged; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Propionates; Quinolines; Randomized Controlled Trials as Topic; Reverse Transcriptase Polymerase Chain Reaction; Rhodamine 123; RNA, Messenger; Survival Analysis; Treatment Outcome; Tumor Cells, Cultured

Tumor necrosis factor (TNF-alpha) is a cytokine with antitumor activity against several cellular models. TNF-alpha-induced apoptosis seems to be mediated by a signaling pathway termed 'sphingomyelin-ceramide' pathway, which consists of the hydrolysis of sphingomyelin and the production of its breakdown product ceramide. Our study shows that KG1a cells, which are inherently resistant to TNF-alpha and do not produce ceramide upon cytokine stimulation, can be sensitized by the use of the P-glycoprotein inhibitor PSC833. Coincubation with 1 microM of this cyclosporin derivative restored the apoptotic potential of 10 ng/ml TNF-alpha. This effect was associated with the restoration of ceramide generation (315%) and activation of neutral, but not acid sphingomyelinase activity (143%). Furthermore, we demonstrate that treatment of KG1a cells with 1 microM PSC833 led to a threefold increase in inner plasma membrane sphingomyelin content and basal neutral sphingomyelinase activity. These results support the hypothesis whereby resistance to TNF-alpha-mediated apoptosis of certain leukemic cells is linked to the disposability of the sphingomyelin pool. These data also suggest a role for P-glycoprotein in sphingomyelin transverse plasma membrane asymmetry.

Topics: Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Survival; Cyclosporins; Humans; Leukemia, Myeloid; Sphingomyelin Phosphodiesterase; Sphingomyelins; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

The multidrug resistance (MDR) modulating activity of SDZ-PSC833 (PSC), a non-immunosuppressive cyclosporine analogue, was investigated and compared with cyclosporin A (CSA) in bone marrow clinical specimens from 45 patients with acute myeloid leukaemia (AML) taken at diagnosis, using double-labelling flow cytometry with simultaneous determination of P-glycoprotein (PGP) expression and intracellular daunorubicin fluorescence (IDF). On the basis of pre-clinical results in multidrug-resistant K562 leukaemic cells, concentrations leading to iso-effective complete restoration of IDF were used: 5 and 10 micromol/l, respectively for PSC and CSA. In the clinical specimens, PGP expression was correlated with a significant decrease in IDE PSC was found to be significantly more potent than CSA since it was found to induce a significant increase in IDF in a higher number of cases and to a higher extent than CSA. PGP-unrelated activity of PSC was also observed in specimens expressing no PGP but exhibiting low IDF, thus probably expressing alternative resistance mechanisms. The results confirm the potency of PSC as MDR-modulating agent in clinical AML specimens whose resistance pattern differed from that of highly resistant cell models and suggest that the activity of PSC is not limited to P-glycoprotein inhibition.

Topics: Acute Disease; Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Bone Marrow; Cyclosporine; Cyclosporins; Daunorubicin; Drug Interactions; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Immunosuppressive Agents; Leukemia, Myeloid; Tumor Cells, Cultured

Multidrug resistance (MDR) mediated by the drug efflux pump P-glycoprotein (Pgp), may cause remission failure and relapse in patients with acute myeloid leukaemia (AML) by extruding cytotoxic agents such as anthracyclines from leukaemic cells thus allowing them to survive. Cell line data suggest that reversal of MDR is possible using modifying drugs such as cyclosporin A (CSA) and its analogue PSC 833. We have investigated the effects on cell kill of the addition of CSA and PSC 833 to daunorubicin, idarubicin, mitozantrone, etoposide and cytarabine in 52 fresh cell samples from AML patients using an MTT assay. Pgp status was determined by using monoclonal antibodies JSB-1 and MRK-16 and by assessment of rhodamine efflux. Although overall each cytotoxic-modifier combination produced significant improvements in cell kill compared to cytotoxic alone (P values ranged from P < 0.001 to P = 0.017), modifiers also produced significant cytotoxicity in their own right, and no consistent difference was seen between responses in Pgp-positive and negative groups. Up to one in three Pgp-positive samples failed to show any improvement in cell kill with the addition of CSA or PSC 833, possibly owing to co-expression of alternative resistance mechanisms not affected by the MDR modifiers. The best responses were seen when PSC 833 was added to idarubicin, with 7 out of 22 Pgp-positive cases (32%) showing five-fold improvements in cell kill or better compared to idarubicin alone. Comparison of equimolar concentrations of the two modifiers in the Pgp positive group failed to show a significant difference in cell kill, though PSC 833 was markedly superior to CSA in a minority of highly responsive samples which demonstrated clear evidence of MDR reversal. Our in vitro data suggest that MDR modifiers such as CSA and PSC 833 could play an important role in the therapy of AML and indicate the need for prospective randomised trials to assess their clinical efficacy.

Topics: Acute Disease; Adolescent; Adult; Aged; Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Cell Survival; Coloring Agents; Cyclosporine; Cyclosporins; Cytarabine; Daunorubicin; Drug Resistance, Neoplasm; Drug Synergism; Etoposide; Female; Humans; Idarubicin; Leukemia, Myeloid; Male; Middle Aged; Mitoxantrone; Tetrazolium Salts; Thiazoles; Tumor Cells, Cultured

SDZ PSC833 (PSC833), an analogue of cyclosporines, is one of the most potent modulators of multi-drug resistance (MDR). We previously reported that MRK-16, an anti-P-glycoprotein MAb, enhanced MDR reversal activity of cyclosporin A (CsA) through inhibition of P-glycoprotein-mediated CsA transport. We have examined here whether MRK-16 can enhance MDR reversal activity of PSC833. We found that MRK-16 potentiated the MDR reversal activity of PSC833, and of CsA, in MDR sublines of human myelocytic leukemia K562 and human ovarian cancer A2780 cells. Like MRK-16 combined with CsA, MRK-16 enhanced the effect of a sub-optimum dose of PSC833 on vincristine accumulation in MDR cells. However, MRK-16 could not increase cellular accumulation of PSC833 in MDR tumor cells, yet it could increase cellular accumulation of CsA. P-glycoprotein could not transport PSC833 but could transport CsA. Our results indicate that MRK-16 potentiates the MDR reversal activity of both PSC833 and CsA, yet also suggest that the molecular mechanism of the potentiation differs between the two substances.

Topics: Affinity Labels; Antibodies, Monoclonal; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cyclosporine; Cyclosporins; Drug Resistance, Multiple; Drug Synergism; Humans; Leukemia, Myeloid; Tumor Cells, Cultured; Vincristine

A non-immunosuppressive cyclosporin, SDZ PSC 833 (PSC833), shows a reversal effect on multidrug resistance (MDR) by functional modulation of MDR1 gene product, P-glycoprotein. The objective of the present study was to compare the reversal efficacy of three multidrug resistance modulators, PSC833, cyclosporin A (CsA) and verapamil (Vp). PSC833 has approximately 3-10-fold greater potency than CsA and Vp with respect to the restoring effect on reduced accumulation of doxorubicin (ADM) and vincristine (VCR) in ADM-resistant K562 myelogenous leukemia cells (K562/ADM) in vitro and also on the sensitivity of K562/ADM to ADM and VCR in in vitro growth inhibition. The in vivo efficacy of a combination of modifiers (PSC833 and CsA: 50 mg/kg, Vp 100 mg/kg administered p.o. 4 h before the administration of anticancer drugs) with anticancer drugs (ADM 2.5 mg/kg i.p., Q4D days 1, 5 and 9, VCR 0.05 mg/kg i.p., QD days 1-5) was tested in ADM-resistant P388-bearing mice. PSC833 significantly enhanced the increase in life span by more than 80%, whereas CsA and Vp enhanced by less than 50%. This reversal potency, which exceeded that of CsA and Vp, was confirmed by therapeutic experiments using colon adenocarcinoma 26-bearing mice. These results demonstrated that PSC833 has significant potency to reverse MDR in vitro and in vivo, suggesting that PSC833 is a good candidate for reversing multidrug resistance in clinical situations.

Topics: Animals; Antineoplastic Agents; Cyclosporine; Cyclosporins; Doxorubicin; Drug Resistance, Multiple; Humans; Leukemia, Myeloid; Mice; Mice, Inbred BALB C; Mice, Inbred Strains; Tumor Cells, Cultured; Verapamil; Vincristine

Cyclosporin A (CsA) was previously found to bind to P-glycoprotein expressed on multidrug-resistant (MDR) cancer cells. In the present study, the effect of CsA on anti-P-glycoprotein monoclonal antibody (mAb)-dependent cell-mediated cytotoxicity (ADCC) against human MDR cells was examined. The ADCC reaction was assessed by 4-h 51Cr-release assay. Highly purified lymphocytes (> 99%) and monocytes (> 99%) obtained from blood mononuclear cells (MNC) of healthy donors were used as effector cells. CsA decreased the cytotoxic activity of MNC against MDR cells, but enhanced their ADCC activity in the presence of anti-P-glycoprotein mAb MRK16. Lymphocyte-mediated ADCC and natural killer activity against MDR cells were also suppressed by addition of CsA. CsA induced a significant dose-dependent increase in monocyte-mediated ADCC activity. Interestingly, pretreatment of MDR cancer cells, but not of monocytes, with CsA significantly enhanced ADCC activity mediated by monocytes, but not by lymphocytes. A CsA analog (PSC833) and FK-506, but not verapamil also increased the sensitivity of MDR cells to ADCC by monocytes. CsA did not affect the binding of monocytes to MDR cells in the presence of MRK16 mAb. These results indicate that CsA may directly enhance the susceptibility of MDR cancer cells to the monocyte-mediated ADCC reaction.

Topics: Antibodies, Monoclonal; Antibody-Dependent Cell Cytotoxicity; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Availability; Carrier Proteins; Cyclosporine; Cyclosporins; Drug Resistance; Female; Humans; KB Cells; Killer Cells, Natural; Leukemia, Myeloid; Lymphocytes; Membrane Glycoproteins; Monocytes; Neoplasm Proteins; Ovarian Neoplasms; Protein Binding; Tacrolimus; Tumor Cells, Cultured; Verapamil

The semiautomated fluorimetric microculture cytotoxicity assay (FMCA) was used for evaluation of the ability of cyclosporin A (CsA) and its novel non-immunosuppressive derivative SDZ PSC 833 (PSC) to modify the response to doxorubicin or vincristine in vitro in different haematological and solid human tumour types. Primary cultures of 322 tumour samples were analysed. Both cyclosporins showed resistance-modifying activity in all haematological tumours tested, and in solid tumours activity was observed in ovarian carcinoma and childhood tumours. Little or no effect was found in the remaining tumour types, including breast, renal and adrenal cortical carcinomas and adult sarcomas. In most of the responsive cases the interaction between the modifier and the cytotoxic drug was synergistic. There was a tendency to higher activity in samples from previously treated patients, and an inverse relationship between degree of cytotoxic drug resistance and resistance-modifying activity was noted. No difference in potency between CsA and PSC could be discerned. The results indicate differential in vitro resistance-modifying activity of the cyclosporins depending on tumour type. The results also suggest that treatment with resistance modifiers should be considered also for primary therapy of drug-sensitive tumours. Drug resistance assays such as the FMCA may become useful in preclinical evaluation of resistance modifiers.

Topics: Antineoplastic Agents; Child; Cyclosporine; Cyclosporins; Doxorubicin; Drug Interactions; Drug Resistance; Drug Screening Assays, Antitumor; Drug Synergism; Female; Fluorometry; Humans; Leukemia, Lymphoid; Leukemia, Myeloid; Lymphoma, Non-Hodgkin; Ovarian Neoplasms; Tumor Cells, Cultured; Vincristine

Overexpression of P-glycoprotein may cause increased efflux of a variety of anticancer drugs (ACD) leading to multidrug resistance (MDR) of tumor cells. Two sublines of murine monocytic leukemia P388 cells were used, one parental (Par-P388) and one multidrug resistant (MDR-P388). In cell growth inhibition assays in vitro, the Par-P388 cells showed a normal sensitivity to daunomycin (DAU) while the MDR-P388 cells were 200-fold resistant. In cellular fluorescence assays, DAU retention in MDR-P388 cells reached only 5% of the level achieved in Par-P388 cells. This cell line pair was used to compare the nonimmunosuppressive cyclosporin analog PSC 833 with several resistance-modifying agents (RMAs) for their in vitro chemosensitizing activity and for their restoration of DAU retention. PSC 833 sensitized the MDR-P388 cells 60- and 140-fold when used at 0.1 and 0.3 micrograms/ml (0.08 and 0.25 microM), respectively, a complete restoration of sensitivity being obtained at 1.0 micrograms/ml PSC 833. Similarly as little as 0.1 micrograms/ml (0.08 microM) PSC 833 was sufficient to restore intracellular DAU retention to 60% of the level found in Par-P388 cells, a 3-fold higher concentration restoring virtually the whole DAU retention. For both these activities, PSC 833 was at least one order of magnitude more active than CsA, which was itself an order of magnitude stronger than verapamil, another RMA already used in clinic. Since PSC 833 had no effect on the PAR-P388 cells, neither on chemosensitization nor on drug retention, it is assumed that it acts on the P-glycoprotein, which is highly expressed on the membrane of the MDR-P388 cells, by inhibiting the function of the P-glycoprotein pump and thus restoring a normal ACD-sensitivity of the MDR-P388 cells.

Topics: Amiodarone; Animals; Cyclosporins; Daunorubicin; Dose-Response Relationship, Drug; Drug Resistance; Flow Cytometry; Leukemia, Experimental; Leukemia, Myeloid; Microscopy, Fluorescence; Quinacrine; Quinidine; Tumor Cells, Cultured; Verapamil