Gemifloxacin mesylate: UV spectrophotometric method for quantitative determination using experimental design for robustness

This study describes the validation of UV spectrophotometric method for quantitative determination of gemifloxacin mesylate (GFM) in tablets using methanol as solvent. The method was specific, linear, precise, exact and robust at 272 and 343 nm. The results confirmed that the method in both wavelengths is valid and useful to the routine quality control of GFM in coated tablets. The validate method was compared to liquid chromatography (HPLC), microbiological assay and visible (VIS) spectrophotometry, which were previously developed and validated to the same drug. There was not significative difference between the methods for GFM quantitation.

Urinary iron excretion induced by intravenous infusion of deferoxamine in ß-thalassemia homozygous patients

The purpose of the present study was to identify noninvasive methods to evaluate the severity of iron overload in transfusion-dependent ß-thalassemia and the efficiency of intensive intravenous therapy as an additional tool for the treatment of iron-overloaded patients. Iron overload was evaluated for 26 ß-thalassemia homozygous patients, and 14 of them were submitted to intensive chelation therapy with high doses of intravenous deferoxamine (DF). Patients were classified into six groups of increasing clinical severity and were divided into compliant and non-compliant patients depending on their adherence to chronic chelation treatment. Several methods were used as indicators of iron overload. Total gain of transfusion iron, plasma ferritin, and urinary iron excretion in response to 20 to 60 mg/day subcutaneous DF for 8 to 12 h daily are useful to identify iron overload; however, urinary iron excretion in response to 9 g intravenous DF over 24 h and the increase of urinary iron excretion induced by high doses of the chelator are more reliable to identify different degrees of iron overload because of their correlation with the clinical grades of secondary hemochromatosis and the significant differences observed between the groups of compliant and non-compliant patients. Finally, the use of 3-9 g intravenous DF for 6-12 days led to a urinary iron excretion corresponding to 4.1 to 22.4% of the annual transfusion iron gain. Therefore, continuous intravenous DF at high doses may be an additional treatment for these patients, as a complement to the regular subcutaneous infusion at home, but requires individual planning and close monitoring of adverse reactions.

Positive response to imatinib mesylate therapy for childhood chronic myeloid leukemia

Chronic myeloid leukemia (CML) is rare in the pediatric population, accounting for 2-3% of childhood leukemia cases, with an annual incidence of one case per million children. The low toxicity profile of imatinib mesylate has led to its approval as a front-line therapy in children for whom interferon treatment has failed or who have relapsed after allogeneic transplantation. We describe the positive responses of 2 children (case 1 - from a 7-year-old male since May 2005; case 2 - from a 5-year-old female since June 2006) with Philadelphia-positive chromosome CML treated with imatinib (300 mg/day, orally) for up to 28 months, as evaluated by morphological, cytogenetic, and molecular approaches. Our patients are alive, are in the chronic phase, and are in continuous morphological complete remission.

In vitro inhibitory effects of imatinib mesylate on stromal cells and hematopoietic progenitors from bone marrow

Imatinib mesylate (IM) is used to treat chronic myeloid leukemia (CML) because it selectively inhibits tyrosine kinase, which is a hallmark of CML oncogenesis. Recent studies have shown that IM inhibits the growth of several non-malignant hematopoietic and fibroblast cells from bone marrow (BM). The aim of the present study was to evaluate the effects of IM on stromal and hematopoietic progenitor cells, specifically in the colony-forming units of granulocyte/macrophage (CFU-GM), using BM cultures from 108 1.5- to 2-month-old healthy Swiss mice. The results showed that low concentrations of IM (1.25 µM) reduced the growth of CFU-GM in clonogenic assays. In culture assays with stromal cells, fibroblast proliferation and α-SMA expression by immunocytochemistry analysis were also reduced in a concentration-dependent manner, with a survival rate of approximately 50% with a dose of 2.5 µM. Cell viability and morphology were analyzed using MTT and staining with acrydine orange/ethidium bromide. Most cells were found to be viable after treatment with 5 µM IM, although there was gradual growth inhibition of fibroblastic cells while the number of round cells (macrophage-like cells) increased. At higher concentrations (15 µM), the majority of cells were apoptotic and cell growth ceased completely. Oil red staining revealed the presence of adipocytes only in untreated cells (control). Cell cycle analysis of stromal cells by flow cytometry showed a blockade at the G0/G1 phases in groups treated with 5-15 µM. These results suggest that IM differentially inhibits the survival of different types of BM cells since toxic effects were achieved.

Thérapie prolongée au mesylate d'imatinib avant la chirurgie pour les tumeurs stromales gastrointestinales avancées : résultats d'une étude prospective de phase II

Les tumeurs stromales gastrointestinales (GIST) sont les néoplasies mésenchymateuses les plus complexes du système gastrointestinal. Le traitement curatif standard de cette pathologie est la chirurgie avec l'obtention de marges microscopiques négatives. Les résultats impressionnants obtenus sur la prolongation de la survie avec l'administration d'imatinib (IM) chez les patients atteints de maladie métastatique et non-réséquable ont suggéré aux cliniciens que ce même médicament pourrait aussi collaborer à l'obtention de marges négatives plus aisément lors de cancer avancé. Jusqu'à présent, aucune étude prospective n'a caractérisée l'effet d'une thérapie néoadjuvante prolongée à l'IM sur la qualité de la résection chirurgicale subséquente. L'objectif de ce projet de maîtrise était d'évaluer l'efficacité de l'imatinib utilisé avant la chirurgie (néoadjuvant) jusqu'à l'obtention d'une réponse maximale, en vue d'augmenter le taux de résection microscopique complète (R0) dans le traitement chirurgical des GIST à haut risque de résection microscopique incomplète (R1) ou impossible (R2). Pour ce faire, une étude prospective multicentrique de phase II a été réalisée. Le traitement néoadjuvant à l'IM a été instauré chez des patients porteurs d'une GIST localement avancée ou métastatique. Au total, quatorze patients ont reçu une dose de 400-600 mg/d d'IM pour une durée de 6-12 mois avant la chirurgie. Quatorze patients ont été inclus dans l'étude. Onze ont eu une chirurgie à visée curative, un patient a démontré une maladie non-réséquable suite à une laparotomie exploratrice et deux patients ont refusé la chirurgie. Après un suivi moyen de 48 mois, tous les patients opérés étaient vivants et sept sans évidence de récidive. L'utilisation prolongée (12 mois) d'IM dans un contexte néoadjuvant est faisable, sécuritaire, efficace et comporte peu de toxicité. De plus, cette approche est associée à des hauts taux de résection complète (R0), tout en permettant une chirurgie moins extensive. Des études de phase III actuellement en cours sont nécessaires afin de confirmer nos résultats.

Frequency of the BCR/ABL rearrangements and associated alterations detected by FISH during monitoring of patients taking imatinib mesylate in isolation

A introdução do mesilato de imatinibe como tratamento da leucemia mielóide crônica tem salvado muitos pacientes, mas o sucesso da terapia tem sido prejudicado pela resistência e possível não destruição do clone maligno. Este artigo descreve a resposta citogenética e padrões citogenéticos anormais envolvendo os genes ABL e BCR detectados por FISH em pacientes em uso exclusivo de imatinibe. Os resultados mostraram que outras alterações envolvendo os genes BCR e ABL não parecem estar relacionadas à resistência à droga, elas ocorrem em baixas freqüências e podem não estar associadas à resposta citogenética ou ao tempo de tratamento. Contudo, a resposta ao imatinibe parece ser individual e imprevisível, independente do tempo e do início do tratamento após o diagnóstico.

Inhibitory effect of deferoxamine on Paracoccidioides brasiliensis survival in human monocytes: Reversal by holotransferrin not by apotransferrin

The mechanisms used by Paracoccidioides brasiliensis to survive into phagocytic cells are not clear. Cellular iron metabolism is of critical importance to the growth of several intracellular pathogens whose capacity to multiply in mononuclear phagocytes is dependent on the availability of intracellular iron. Thus, the objective of this paper was to investigate the role of intracellular iron in regulating the capacity of P. brasiliensis yeast cells to survive within human monocytes. Treatment of monocytes with deferoxamine, an iron chelator, suppressed the survival of yeasts in a concentration-dependent manner. The effect of deferoxamine was reversed by iron-saturated transferrin (holotransferrin) but not by nonsaturated transferrin (apotransferrin). These results strongly suggest that P. brasiliensis survival in human monocytes is iron dependent.

Evaluation of Long-Term Outcomes, Cytogenetic and Molecular Responses with Imatinib Mesylate in Early and Late Chronic-Phase Chronic Myeloid Leukemia: A Report from a Single Institute

Here we compare the management and survival outcomes of chronic myeloid leukemia (CML) patients who had early or late imatinib mesylate (IM) therapy. The cytogenetic and molecular responses of 189 CML patients were analyzed. Of this group, 121 patients were classified as the early chronic phase (ECP) group and started IM within 12 months of diagnosis. The other 68 patients were classified as the late chronic phase (LCP) group who had been treated with interferon (IFN)-alpha-2 and crossed over to IM more than 12 months after diagnosis. The overall rates of complete cytogenetic response (CCyR) and major molecular response (MMR) at last follow-up were 83.6 and 78.1% in the ECP and LCP groups, respectively. The CCyR rates were 89.3 (for ECP patients) versus 73.5% (for LCP patients; p < 0.0001). At last follow-up, 82.4% ECP and 64.2% LCP patients had achieved an MMR (p < 0.0001). No significant differences were noted between the two groups with regard to survival outcomes. Our experience reveals that IM is an effective rescue therapy in most CML LCP patients who are intolerant or in whom IFN-alpha therapy fails. Such therapeutic options should be considered in LCP patients, particularly in countries where IM may not be available. Copyright (C) 2012 S. Karger AG, Basel

Pretherapeutic Expression of the hOCT1 Gene Predicts a Complete Molecular Response to Imatinib Mesylate in Chronic-Phase Chronic Myeloid Leukemia

In this retrospective study we evaluated the pretherapeutic mRNA expression of the hOCT1 (human organic cation transporter 1) gene in patients with chronic-phase (CP) chronic myeloid leukemia (CML) who varied in terms of their response to imatinib (IM). hOCT1 mRNA was quantified by real-time PCR. Patients were classified as expressing either high (n = 44) or low hOCT1 mRNA (n = 44). The complete cytogenetic response rates observed at 6, 12 and 18 months were 47.7, 84.1 and 91%, respectively, in patients with high hOCT1 mRNA and 47.5, 81.8 and 86.3%, respectively, in patients with low hOCT1 transcripts. The major molecular response rates were not significantly different between patients with high and low hOCT1 mRNA after 6 months of therapy (22.7 vs. 9.1%; p = 0.07), but they were significantly different after 12 months (54.5 vs. 31.8%; p = 0.026) and 18 months (77.2 vs. 56.8%; p = 0.034). Complete molecular responses were observed in 5 patients with low and 17 patients with high hOCT1 mRNA (p = 0.003). The 5-year event-free and overall survival analyses revealed no significant differences between the groups. These data imply that knowledge of the pretherapeutic level of hOCT1 could be a useful marker to predict IM therapy outcome in treatment-naive CP CML patients. Copyright (C) 2012 S. Karger AG, Basel

Imatinib mesylate selectively impairs expansion of memory cytotoxic T cells without affecting the control of primary viral infections

Imatinib mesylate (imatinib) is a potent inhibitor of defined tyrosine kinases (TKs) and is effective in the treatment of malignancies characterized by constitutive activation of these TKs such as chronic myeloid leukemia and gastrointestinal stromal tumors. TKs also play an important role in T-cell receptor (TCR) signal transduction. Inhibitory as well as stimulating effects of imatinib on T cells and dendritic cells have been described. Here, we analyzed the effects of imatinib treatment on antiviral immune responses in vivo. Primary cytotoxic T-cell (CTL) responses were not impaired in imatinib-treated mice after infection with lymphocytic choriomeningitis virus (LCMV) or after immunization with a tumor cell line expressing LCMV glycoprotein (LCMV-GP). Similarly, neutralizing antibody responses to vesicular stomatitis virus (VSV) were not affected. In contrast, secondary expansion of LCMV-specific memory CTLs was reduced in vitro and in vivo, resulting in impaired protection against reinfection. In addition, imatinib treatment delayed the onset of diabetes in a CTL-induced diabetes model. In summary, imatinib treatment in vivo selectively inhibits the expansion of antigen-experienced memory CTLs without affecting primary T- or B-cell responses. Therefore, imatinib may be efficacious in the suppression of CTL-mediated immunopathology in autoimmune diseases without the risk of acquiring viral infections.

Effects of clinically used antioxidants in experimental pneumococcal meningitis

Reactive oxygen intermediates mediate brain injury in bacterial meningitis. Several antioxidant drugs are clinically available, including N-acetylcysteine (NAC), deferoxamine (DFO), and trylizad-mesylate (TLM). The present study evaluated whether these antioxidants are beneficial in a model of pneumococcal meningitis. Eleven-day-old rats were infected intracisternally with Streptococcus pneumoniae and randomized to intraperitoneal treatment every 8 h with NAC (200 mg/kg), DFO (100 mg/kg), TLM (10 mg/kg), or saline (250 microL). TLM-treated animals showed a significantly reduced mortality compared with controls (P<.03). Meningitis led to extensive cortical injury at 22+/-2.2 h after infection (median, 14. 6% of cortex; range, 0-61.1%). Injury was significantly (P<.01) reduced to 1.1% (range, 0-34.6%) by NAC, to 2.3% (range, 0-19.6%) by DFO, and to 0.2% (range, 0-36.9%) by TLM (the difference was not significant among the 3 groups). None of the drugs reduced hippocampal injury. Thus, several clinically used antioxidants reduced cortical injury in experimental pneumococcal meningitis.

Molecular mechanisms of response in gastrointestinal stromal tumors treated with imatinib mesylate

Gastrointestinal stromal tumors (GIST) represent 80% of sarcoma arising from the GI tract. The inciting event in tumor progression is mutation of the kit or, rarely, platelet derived growth factor receptor-α (PDGFR) gene. These mutations encode ligand independent, constitutively active proteins: Kit or PDGFR. ^ These tumors are notoriously chemo and radio resistant. Historically, patients with advanced disease realized a median overall survival of 9 months. However, with modern management of GIST with imatinib mesylate (Novartis), a small molecule inhibitor of the Kit, PDGFR, and Abl tyrosine kinases, patients now realize a median overall survival greater than 30 months. However, almost half of patients present with surgically resectable GIST and the utility of imatinib in this context has not been prospectively studied. Also, therapeutic benefit of imatinib is variable from patient to patient and alternative targeted therapy is emerging as potential alternatives to imatinib. Thus, elucidating prognostic factors for patients with GIST in the imatinib-era is crucial to providing optimal care to each particular patient. Moreover, the exact mechanism of action of imatinib in GIST is not fully understood. Therefore, physicians find difficulty in accurately predicting which patient will benefit from imatinib, how to assess response to therapy, and the time at which to assess response. ^ I have hypothesized that imatinib is tolerable and clinically beneficial in the context of surgery, VEGF expression and kit non-exon 11 genotypes portend poor survival on imatinib therapy, and imatinib's mechanism of action is in part due to anti-vascular effects and inhibition of the Kit/SCF signaling axis of tumor-associated endothelial cells. ^ Results herein demonstrate that imatinib is safe and increases the duration of disease-free survival when combined with surgery. Radiographic and molecular (namely, apoptosis) changes occur within 3 days of imatinib initiation. I illustrate that non-exon 11 mutant genotypes and VEGF are poor prognostic factors for patients treated with imatinib. These findings may allow for patient stratification to emerging therapies rather than imatinib. I show that imatinib has anti-vascular effects via inducing tumor endothelial cell apoptosis perhaps by abrogation of the Kit/SCF signaling axis. ^

A systematic review of the adverse events of imatinib mesylate in the treatment of chronic myeloid leukemia.

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