Anthracyclines in haematology: pharmacokinetics and clinical studies

Diversifying the anthracycline class of anti-cancer drugs identifies aclarubicin for superior survival of acute myeloid leukemia patients

The efficacy of anthracycline-based chemotherapeutics, which include doxorubicin and its structural relatives daunorubicin and idarubicin, remains almost unmatched in oncology, despite a side effect profile including cumulative dose-dependent cardiotoxicity, therapy-related malignancies and infertility. Detoxifying anthracyclines while preserving their anti-neoplastic effects is arguably a major unmet need in modern oncology, as cardiovascular complications that limit anti-cancer treatment are a leading cause of morbidity and mortality among the 17 million cancer survivors in the U.S. In this study, we examined different clinically relevant anthracycline drugs for a series of features including mode of action (chromatin and DNA damage), bio-distribution, anti-tumor efficacy and cardiotoxicity in pre-clinical models and patients. The different anthracycline drugs have surprisingly individual efficacy and toxicity profiles. In particular, aclarubicin stands out in pre-clinical models and clinical studies, as it potently kills cancer cells, lacks cardiotoxicity, and can be safely administered even after the maximum cumulative dose of either doxorubicin or idarubicin has been reached. Retrospective analysis of aclarubicin used as second-line treatment for relapsed/refractory AML patients showed survival effects similar to its use in first line, leading to a notable 23% increase in 5-year overall survival compared to other intensive chemotherapies. Considering individual anthracyclines as distinct entities unveils new treatment options, such as the identification of aclarubicin, which significantly improves the survival outcomes of AML patients while mitigating the treatment-limiting side-effects. Building upon these findings, an international multicenter Phase III prospective study is prepared, to integrate aclarubicin into the treatment of relapsed/refractory AML patients.

Synthesis, Structure and Cytotoxicity Testing of Novel 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-Imine Derivatives

The appropriate 1-arylhydrazinecarbonitriles 1a-c are subjected to the reaction with 2-chloro-4,5-dihydro-1H-imidazole (2), yielding 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-imines 3a-c, which are subsequently converted into the corresponding amides 4a-e, 8a-c, sulfonamides 5a-n, 9, ureas 6a-I, and thioureas 7a-d. The structures of the newly prepared derivatives 3a-c, 4a-e, 5a-n, 6a-i, 7a-d, 8a-c, and 9 are confirmed by IR, NMR spectroscopic data, as well as single-crystal X-ray analyses of 5e and 8c. The in vitro cytotoxic potency of these compounds is determined on a panel of human cancer cell lines, and the relationships between structure and antitumor activity are discussed. The most active 4-chloro-N-(2-(4-chlorophenyl)-7-(4,5-dihydro-1H-imidazol-2-yl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)benzamide (4e) and N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-[1,1'-biphenyl]-4-sulfonamide (5l) inhibits the growth of the cervical cancer SISO and bladder cancer RT-112 cell lines with IC50 values in the range of 2.38-3.77 μM. Moreover, N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-phenyl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-4-phenoxybenzenesulfonamide (5m) has the best selectivity towards the SISO cell line and induces apoptosis in this cell line.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in Treating Non-Hodgkin Lymphoma

Non-Hodgkin lymphoma (NHL) includes a variety of closely related malignancies that originate from lymphoid precursors. The majority of NHLs are of B-cell lineage, for which traditional therapy involves chemotherapy in combination with the anti-CD20 monoclonal antibody rituximab. Ongoing research into the pathogenesis of NHL subtypes has given rise to the use of novel agents that target specific molecular pathways. While the incidence of NHL extends over a range of ages from pediatric to elderly settings, the majority of diagnoses occur over age 60 years. Increasing the use of concomitant medication coupled with declining organ function among this group of patients creates pharmacokinetic (PK) challenges in administering a number of agents involved in the treatment of NHL. In addition, since many of the new agents are administered orally, there are a number of added PK factors that must be taken into consideration with their prescribing and administration. This article will review the available literature on the PK and pharmacodynamic properties of agents commonly used in the treatment of NHL, and intends to provide information that can assist with properly using these drugs in this setting.

Enhancement of Tumor Homing by Chemotherapy-Loaded Nanoparticles

Targeted delivery of anticancer drugs with nanocarriers can reduce side effects and ameliorate therapeutic efficacy. However, poorly perfused and dysfunctional tumor vessels limit the transport of the payload into solid tumors. The use of tumor-penetrating nanocarriers might enhance tumor uptake and antitumor effects. A peptide containing a tissue-penetrating (TP) consensus motif, capable of recognizing neuropilin-1, is here fused to a neuroblastoma-targeting peptide (pep) previously developed. Neuroblastoma cell lines and cells derived from both xenografts and high-risk neuroblastoma patients show overexpression of neuropilin-1. In vitro studies reveal that TP-pep binds cell lines and cells derived from neuroblastoma patients more efficiently than pep. TP-pep, after coupling to doxorubicin-containing stealth liposomes (TP-pep-SL[doxorubicin]), enhances their uptake by cells and cytotoxic effects in vitro, while increasing tumor-binding capability and homing in vivo. TP-pep-SL[doxorubicin] treatment enhances the Evans Blue dye accumulation in tumors but not in nontumor tissues, pointing to selective increase of vascular permeability in tumor tissues. Compared to pep-SL[doxorubicin], TP-pep-SL[doxorubicin] shows an increased antineuroblastoma activity in three neuroblastoma animal models mimicking the growth of neuroblastoma in humans. The enhancement of drug penetration in tumors by TP-pep-targeted nanoparticles may represent an innovative strategy for neuroblastoma.

Monitoring subcellular biotransformation of N-L-leucyldoxorubicin by micellar electrokinetic capillary chromatography coupled to laser-induced fluorescence detection

Development of prodrugs is a promising alternative to address cytotoxicity and nonspecificity of common anticancer agents. N-L-leucyldoxorubicin (LeuDox) is a prodrug that is biotransformed to the anticancer drug doxorubicin (Dox) in the extracellular space; however, its biotransformation may also occur intracellularly in endocytic organelles. Such organelle-specific biotransformation is yet to be determined. In this study, magnetically enriched endocytic organelle fractions from human uterine sarcoma cells were treated with LeuDox. Micellar electrokinetic chromatography with laser-induced fluorescence detection (MEKC-LIF) was used to determine that 10% of LeuDox was biotransformed to Dox, accounting for ~43% of the biotransformation occurring in the post-nuclear fraction. This finding suggests that endocytic organelles also participate in the intracellular biotransformation of LeuDox to Dox.

ABCC1 polymorphisms in anthracycline-induced cardiotoxicity in childhood acute lymphoblastic leukaemia

Anthracyclines are potent cytostatic drugs, the correct dosage being critical to avoid possible cardiac side effects. ABCC1 [ATP-binding cassette, sub-family C, member 1; also denoted as MRP1 (multidrug resistance-associated protein 1)] is expressed in the heart and takes part in the detoxification and protection of cells from the toxic effects of xenobiotics, including anthracyclines. Our objective was to search for associations between LV (left ventricular) function and single-nucleotide polymorphisms of the ABCC1 gene in children receiving anthracycline chemotherapy. Data of 235 paediatric patients with acute lymphoblastic leukaemia was analysed. Patients were followed-up by echocardiography (median follow-up 6.3 years). Nine polymorphisms in the ABCC1 gene were genotyped. The ABCC1 rs3743527TT genotype and rs3743527TT–rs246221TC/TT genotype combination were associated with lower LVFS (left ventricular fractional shortening) after chemotherapy. The results suggest that genetic variants in the ABCC1 gene influence anthracycline-induced LV dysfunction.

miR-181a sensitizes a multidrug-resistant leukemia cell line K562/A02 to daunorubicin by targeting BCL-2

The aim of this study was to investigate whether miR-181a could modulate the sensitivity of the leukemia drug-resistant cell line K562/A02 to the chemotherapeutic agent daunorubicin (DNR), and explore the mechanism of miR-181a on the DNR sensitivity of K562/A02 cells. MicroRNA microarray and stem-loop reverse transcription-polymerase chain reaction were used to detect the expression of miR-181a. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay was performed to quantify the effect of miR-181a on K562 cells growth and viability. Apoptotic cells were quantitatively detected using Annexin V/FITC and PI apoptosis detection kit. BCL-2 protein expression was measured by western blot. Luciferase reporter vector with the putative BCL-2 3' untranslated region was constructed to explore whether BCL-2 was a direct target gene of miR-181a. BCL-2 siRNA was transfected into the cell to explore the relationship between BCL-2 and DNR resistance. The miR-181a expression level was lower in the K562/A02 cells than in the K562 cells (P< 0.05). K562 cells that were transfected with miR-181a inhibitor had a significantly higher survival than K562 cells, and K562/A02 cells that were transfected with the miR-181a mimic had a significantly lower survival than K562/A02 cells (P< 0.05). miR-181a could enhance DNR-induced apoptosis in K562/A02 cells. BCL-2 siRNA transfected K562/A02 cells had decreased survival compared with the K562/A02 control group. In conclusion, miR-181a could play a role in the development of DNR resistance in K562/A02 cells and the over-expression of miR-181a could sensitize K562/A02 cells to DNR by targeting BCL-2.

Anthracycline-related cardiomyopathy after childhood cancer: role of polymorphisms in carbonyl reductase genes--a report from the Children's Oncology Group

PURPOSE

Carbonyl reductases (CBRs) catalyze reduction of anthracyclines to cardiotoxic alcohol metabolites. Polymorphisms in CBR1 and CBR3 influence synthesis of these metabolites. We examined whether single nucleotide polymorphisms in CBR1 (CBR1 1096G>A) and/or CBR3 (CBR3 V244M) modified the dose-dependent risk of anthracycline-related cardiomyopathy in childhood cancer survivors.

PATIENTS AND METHODS

One hundred seventy survivors with cardiomyopathy (patient cases) were compared with 317 survivors with no cardiomyopathy (controls; matched on cancer diagnosis, year of diagnosis, length of follow-up, and race/ethnicity) using conditional logistic regression techniques.

RESULTS

A dose-dependent association was observed between cumulative anthracycline exposure and cardiomyopathy risk (0 mg/m(2): reference; 1 to 100 mg/m(2): odds ratio [OR], 1.65; 101 to 150 mg/m(2): OR, 3.85; 151 to 200 mg/m(2): OR, 3.69; 201 to 250 mg/m(2): OR, 7.23; 251 to 300 mg/m(2): OR, 23.47; > 300 mg/m(2): OR, 27.59; P(trend) < .001). Among individuals carrying the variant A allele (CBR1:GA/AA and/or CBR3:GA/AA), exposure to low- to moderate-dose anthracyclines (1 to 250 mg/m(2)) did not increase the risk of cardiomyopathy. Among individuals with CBR3 V244M homozygous G genotypes (CBR3:GG), exposure to low- to moderate-dose anthracyclines increased cardiomyopathy risk when compared with individuals with CBR3:GA/AA genotypes unexposed to anthracyclines (OR, 5.48; P = .003), as well as exposed to low- to moderate-dose anthracyclines (OR, 3.30; P = .006). High-dose anthracyclines (> 250 mg/m(2)) were associated with increased cardiomyopathy risk, irrespective of CBR genotype status.

CONCLUSION

This study demonstrates increased anthracycline-related cardiomyopathy risk at doses as low as 101 to 150 mg/m(2). Homozygosis for G allele in CBR3 contributes to increased cardiomyopathy risk associated with low- to moderate-dose anthracyclines, such that there seems to be no safe dose for patients homozygous for the CBR3 V244M G allele. These results suggest a need for targeted intervention for those at increased risk of cardiomyopathy.

Involvement of miR-21 in resistance to daunorubicin by regulating PTEN expression in the leukaemia K562 cell line

Recent studies have shown microRNA-21 (miR-21) is overexpressed in several types of cancer and contributes to tumor resistance to chemotherapy. In this study, we investigated whether miR-21 mediated resistance of the leukaemia cell line K562 to the chemotherapeutic agent daunorubicin (DNR). miR-21 expression was upregulated in the DNR resistant cell line K562/DNR compared to its parental line K562. Stable transfection of miR-21 induced drug resistance in K562, while suppression of miR-21 in K562/DNR led to enhanced DNR cytotoxicity. Additional experiments indicate that the mechanism of miR-21 drug resistance involves the PI3K/Akt pathway and changes following PTEN protein expression. This study provides a novel mechanism for understanding leukaemia drug resistance.

Haemotoxicity of busulphan, doxorubicin, cisplatin and cyclophosphamide in the female BALB/c mouse using a brief regimen of drug administration

Many anticancer drugs are myelotoxic and cause bone marrow depression; however, generally, the marrow/blood returns to normal after treatment. Nevertheless, after the administration of some anti-neoplastic agents (e.g. busulphan, BU) under conditions as yet undefined, the marrow may begin a return towards normal, but normality may not be achieved, and late-stage/residual marrow injury may be evident. The present studies were conducted to develop a short-term mouse model (a 'screen') to identify late-stage/residual marrow injury using a brief regimen of drug administration. Female BALB/c mice were treated with BU, doxorubicin (DOX), cisplatin (CISPLAT) or cyclophosphamide (CYCLOPHOS) on days 1, 3 and 5. In 'preliminary studies', a maximum tolerated dose (MTD) for each drug was determined for use in 'main studies'. In main studies, mice were treated with vehicle (control), low and high (the MTD) dose levels of each agent. Necropsies were performed, and blood parameters and femoral/humeral nucleated marrow cell counts (FNCC/HNCC) were assessed on six occasions (from days 1 to 60/61 post-dosing). Late-stage/residual changes were apparent in BU-treated mice at day 61 post-dosing: RBC, Hb and haematocrit were reduced, mean cell volume/mean cell haemoglobin were increased and platelet and FNCC counts were decreased. Mice given DOX, CISPLAT and CYCLOPHOS, in general, showed no clear late-stage/residual effects (day 60/61). It was concluded that a brief regimen of drug administration, at an MTD, with assessment at day 60/61 post-dosing was a suitable short-term method/screen in the mouse for detecting late-stage/residual marrow injury for BU, a drug shown to exhibit these effects in man.

Anthracycline-Induced Cardiotoxicity in Adult Hematologic Malignancies

Anthracyclines are a highly efficacious treatment for adult hematologic malignancies, including acute myeloid leukemia, acute lymphoblastic leukemia, multiple myeloma, Hodgkin's disease, and non-Hodgkin's lymphoma. The consequences of anthracycline-induced cardiotoxicity have obliged hematologists to set empirical dose limits, above which the cardiotoxic risk is deemed unacceptable. However, subclinical (and also clinical) cardiotoxicity occurs below these empirical doses and may begin to induce cardiac damage in an unpredictable and progressive manner after the first dose of treatment. As a result, treatment with anthracyclines may be withdrawn from patients prematurely or substituted with less efficacious alternative therapies. Through discontinuing further use of anthracyclines, relapsed patients previously treated with these agents may consequently be treated with second-line therapy that is less effective and possibly less well tolerated. Anthracycline-induced cardiotoxicity is potentially fatal and can significantly impair patients' quality of life, while also substantially increasing health care costs.

Differential toxicity of anthracyclines on cultured endothelial cells

Anthracyclines are known for their endothelial toxicity. Newer derivatives may have fewer toxic effects on endothelium. The authors therefore evaluated the effects of doxorubicin, doxorubicin analogs (daunorubicin, idarubicin), and pegylated liposomal doxorubicin (doxil) in human coronary artery endothelial cells (HCAECs). Endothelial viability did not change significantly with doxil, but was decreased with doxorubicin, daunorubicin, or idamycin. Similarly caspase-3 activity was significantly elevated in HCAECs treated with doxorubicin, daunorubicin, and idamycin. In contrast, doxil did not cause significant increase in caspase activity. The authors also characterized the levels of antiapoptotic and prosurvival proteins using Western blot analysis. There was no significant difference in the expression levels of Bcl-2, Bax, and phospho-Akt in endothelial cells treated with anthracycline derivatives. However, the expression levels of Mcl-l protein were unaltered in endothelial cells treated with doxil but were significantly decreased when treated with other anthracycline analogs. Doxil minimally affected the expression levels of p53, whereas other anthracyclines induced p53 protein levels to a significant level, resulting in endothelial cell apoptosis. The authors conclude that the liposomal anthracycline protects endothelial cells from injury by preventing caspase-3 activation and maintaining the expression of antiapoptotic molecule Mcl-1.

Anthracycline-induced cardiomyopathy: long-term effects on myocardial cell integrity, cardiac adrenergic innervation and fatty acid uptake

Cardiotoxicity of anthracyclines is a clinical challenge in cancer chemotherapy. Limited data is available on the physiological mechanisms responsible for anthracycline-induced heart failure or its recovery. We studied four patients with a history of severe anthracycline-induced heart failure manifested 2-116 months earlier by using radionuclide ventriculography for the measurement of left ventricular function, indium-111-antimyosin scintigraphy for the detection of myocardial cell injury and iodine-123-metaiodobenzylguanidine (MIBG) scintigraphy for the assessment of cardiac adrenergic innervation. Myocardial perfusion and fatty acid utilization were assessed with iodine-123-paraphenyl pentadecanoid acid (pPPA) and single photon emission computed tomography (SPECT). Symptoms of congestive heart failure (CHF) were still present in two patients whereas the others were asymptomatic at the time of the study. The patients who showed complete clinical recovery had normal or near normal left ventricular ejection fraction (LVEF) (47 and 52%), whereas the patients with symptoms of heart failure had low ejection fractions (21 and 31%). All patients presented with abnormal antimyosin uptake and decreased myocardial MIBG uptake. Patients with low ejection fraction tended to have higher antimyosin uptake suggesting more severe, persistent myocyte injury. All but one patient showed normal fatty acid utilization. These data suggest that patients with a history of severe anthracycline-induced cardiomyopathy have persistent myocardial cell injury and adrenergic dysfunction up to 10 years after the development of heart failure. These findings seem to be present regardless of recovery of left ventricular function.

Oral idarubicin in patients with late chronic phase chronic myelogenous leukemia or chronic myelomonocytic leukemia

Patients with chronic myelogenous leukemia (CML) who have failed or cannot receive interferon alpha (IFN-alpha) based regimens or patients with advanced chronic myelomonocytic leukemia (CMML) have very limited current therapeutic options. Hence, there is a need to develop new strategies for these patients. This study was undertaken to determine the efficacy and toxicity of a chronic low-dose oral idarubicin regimen in these patients as positive data has been generated on this agent in shorter schedules given to patients with other hematological malignancies. Eighteen patients were treated on study. The starting dose of oral idarubicin was 2 to 5 mg/m2 daily depending in initial WBC count. This dose was escalated in the absence of Grade 4 myelosuppression or Grade 3 or 4 extramedullary toxicity. Oral idarubicin was given daily for 28 days followed by a 21 day break off treatment in repeated cycles until there was evidence of disease progression or intolerable toxicity. The dose of idarubicin was adjusted, at 2-week intervals, by 25% to maintain a white blood cell (WBC) count between 2 and 4x10(9)/L and a platelet count of >75x10(9)/L. The dose was reduced by 25% for grade 2 extramedullary toxicity and held until toxicity resolved to grade 2 or better for grade 3 toxicity. Oral idarubicin was then restarted at 75% of the initial dose. Five out of 14 CML patients achieved a complete hematologic remission. No CMML patient responded (median survival 3 months). The overall median survival was 24 months. CML patients had a median survival of 28 months. Major toxicities (myelosuppression, gastrointestinal, cardiac) were infrequent with a median cumulative dose of 1110 mg/m2 (range 54-9750). Five patients have received oral idarubicin for > 1 year with no overt cardiotoxicity, reaching median cumulative dose of 2756 mg/m2 (range 2550-9750) which is higher than those documented in prior studies. We conclude that oral idarubicin is sufficiently safe and active to warrant phase II studies investigating it as part of interferon-based regimens in patients with advanced CML.

Cellular uptake and antiproliferative effects of therapeutic concentrations of idarubicin or daunorubicin and their alcohol metabolites, with or without cyclosporin A, in MDR1+ human leukemic cells

Ways of restoring an altered drug sensitivity in P-170 glycoprotein (MDR1) positive leukemias are being actively sought for, mostly using MDRI negative regulators together with the MDR1-sensitive anthracycline-type drugs daunorubicin and mitoxantrone. Because idarubicin is less vulnerable to MDR1-mediated transport and could thereby represent a better companion to MDR1 inhibitors, we assessed the ability of the anti-MDR1 agent cyclosporin A to modulate this function in multidrug resistant T-lymphoblastic CEM cells challenged in vitro with either daunorubicin or idarubicin. In order to obtain information of potential interest for the design of a clinical trial, we adopted drug plus metabolite concentrations and exposure times close to the in vivo pharmacokinetics of equimyelotoxic doses of intravenous daunorubicin 45 mg/m2 or idarubicin 10-12 mg/m2, respectively, plus infusional cyclosporin A 16 mg/kg/d. Study methods were cytofluorimetry for the detection of intracellular drug uptake, retention and pro-apoptotic effects (binding of fluoresceinated annexin V), and the standard MTT assay as growth inhibition test. The results showed significantly greater drug uptake (at 30'), retention (at 12 hours), and apoptotic cell rates with idarubicin+/-idarubicinol than daunorubicin+/-daunorubicinol (p<0.05), and a further potentiation of these effects by cyclosporin A. Differing from daunorubicin, idarubicin intracellular accumulation and, by inference, related apoptotic changes were increased by cyclosporin A only in the early phase of drug-cell interaction; a potential advantage towards a reduced toxicity by CsA delivered as short rather than prolonged infusion in the in vivo setting. MTT assay results were also in favour of idarubicin but greatly influenced by cyclosporin A itself. Altogether, study results in MDR1+ cells incubated with CsA 1500 ng/ml plus idarubicin+idarubicinol 100+20 ng/ml, that are peak levels achievable in vivo with an idarubicin dose > or = 12 mg/m2 plus cyclosporin A 16 mg/kg/d, were in the range of those obtained with standard-dose daunorubicin in MDR1- cells (p=n.s.). In summary, an idarubicin plus short-course cyclosporin A combination could be considered for the management of MDR1+ leukemias, where it may represent a more effective and less toxic option than daunorubicin plus continuous infusion cyclosporin A.