STI-571 (Imatinib/Glivec) has been shown to have synergism with various chemotherapeutic agents including cytosine arabinoside (Ara-C) in BCR/ABL positive leukemia cells. The antiproliferative and ...proapopotic effects of STI-571 in these experiments are mainly explained by its ability to specifically block the fusion-protein BCR/ABL which has a constitutively active tyrosine kinase activity. We investigated the effects of STI-571 in combination with Ara-C on BCR/ABL negative leukemia cell lines and CD34+ hematopoietic progenitor cells in-vitro. Raji, HL-60, K562, Kasumi and KG1a leukemia cells and CD34+ cells from healthy donors were incubated with 5-20 microg/ml Ara-C for 5 h alone or in combination with 10 microg/ml STI-571. Intracellular levels of Ara-CTP measured by HPLC were increased 1.5-3 fold in leukemia cells with most promiment effects in HL-60, Kasumi and Raji cells. In HL-60 cells a linear correlation between the concentration of STI-571 (1-10 microg/ml) and the subsequent levels of Ara-CTP was observed. A linear increase of Ara-CTP could be induced by increasing the incubation time with STI-571 from 2-6 h with a ceiling effect after 8 h. In contrast coincubation of mononuclear cells or purified CD34+ cells with STI-571 at therapeutic concentrations lead to decreased intracellular levels of Ara-CTP. The synergism between Ara-C and STI-571 was even more pronounced in Raji and HL-60 cells when 300 ng/ml G-CSF were added at the beginning of the culture period. Intracellular measurements of STI-571 revealed no decreased or increased levels of the compound when increasing Ara-C concentrations were used. Our findings indicate that STI-571 can have significant impact on nucleoside metabolism in malignant and non-malignant hematopoietic cells. Further investigations will have to show whether theses effects can lead to increased cytotoxicity in primary blasts of patients with acute leukemia.
Therapy for patients with hepatic metastases from colorectal cancer (CRC) remains controversial and may be improved by regional oxaliplatin which proved to be effective when administered systemically ...to patients with advanced CRC.
During the current study, which aims to determine the maximum tolerated dose, the dose-limiting toxicity, and the pharmacokinetics of oxaliplatin applied as hepatic intra-arterial infusion combined with folinic acid and 5-fluorouracil in patients with hepatic metastases from CRC, serial levels of carcino-embryonic antigen were determined and their relationship to response to therapy was assessed.
Toxicity mainly consisted of nausea, pain, mucositis, sensorial neuropathy, diarrhoea, and thrombocytopenia. The results of tumor marker analyses suggest that progressive disease may be detected early by increasing CEA levels and responsive disease may be characterized by low or decreasing values.
Further analyses are warranted to determine the role of CEA in the assessment of response as compared to imaging techniques.
A 40-year-old patient with low-grade B-NHL developed a generalized macular-papular rash following the first cycle of fludarabine treatment which progressed to a complete epidermal necrolysis ...following the second cycle. Clinical symptoms and the results of the direct and indirect immunofluorescence were consistent with a mucocutaneous autoimmune syndrome (pemphigus). Immunohistochemical analysis demonstrated a dense epidermal infiltration of CD8+ lymphocytes associated with the histological features of single-cell necrosis of keratinocytes. Early and aggressive immunosuppressive treatment with steroids, cyclophosphamide, and high-dose immunoglobulins resulted in regression of symptoms and complete reconstitution of epidermal integrity. The malignant lymphoma has completely regressed. The findings suggest a fludarabine-induced defect in immunosurveillance--resulting in the uncontrolled activation of autoaggressive T-cell clones--as a pathogenetic mechanism of this life-threatening dermatological complication.
Background:
Splicing factor (SF) mutations are recurrent events in hematopoietic malignancies. Their clinical characteristics and aberrant splicing patterns have been explored in myelodysplasia, ...however their role in acute myeloid leukaemia (AML) is not well defined.
Aims:
The aim of this study was the comprehensive clinical and functional analysis of AML samples with mutations in the three most commonly afflicted splicing factor genes, SRSF2, U2AF1 and SF3B1.
Methods:
To this end, we determined co‐occurence of SF mutations and other recurrent alterations in AML and examined their prognostic role in two large independent cohorts, encompassing a total of 2442 intensively treated patients. The clinical analysis was complemented by RNA sequencing of 246 patients to quantify differential isoform expression and identify targets of splicing dysregulation.
Results:
As shown before, SF mutations occur more frequently in secondary AML and are associated with older age. Additionally, mutations in all three SF genes co‐occur significantly with BCOR and RUNX1 mutations and display an exclusion pattern with NPM1 mutations. Splicing factor mutations associate with inferior relapse‐free and overall survival. However, in multivariate models including parameters of the ELN 2017 classification, mutations in SRSF2 and SF3B1 do not represent distinct independent prognostic markers. U2AF1 mutations still have inferior relapse‐free survival in the multivariate model, while patients with the specific point mutation U2AF1 (S34F) show inferior overall survival as well.
In RNA sequencing, we found differential expression to be restricted to a small number of transcript isoforms, some of which displayed large fold‐change differences between SF mutated and SF wildtype patients. We found little overlap of affected isoforms between patients harboring different SF mutations. Hierarchical clustering of the samples based on differential expression revealed a splicing profile highly characteristic for each individual SF mutation. Gene ontology analysis revealed several enriched pathways, including but not limited to genes involved in cell proliferation, apoptosis, and immune response.
Moreover, we determined differential splice junction usage of both known and novel splice junctions. We detected genome‐wide aberrant splicing which was characterized by motif‐dependent, decreased splice junction utilization in SF mutated samples. The affected sites included both novel and non‐canonical splice junctions. Targets of splicing dysregulation included several genes with a well‐known role in cancer, such as NPM1, TET2 and WT1. Furthermore, we identified aberrant splicing patterns in most of the isoforms (78.9%) we determined previously as differentially expressed.
Summary/Conclusion:
In summary, these results verify the known associations of SF mutations with distinct AML markers and provide evidence of previously unknown correlations. At the same time, they suggest that while SF mutations associate with inferior survival, they are not clear independent prognostic markers. Our findings support previous studies that have characterized SF mutations as “change‐of‐function”, however they also introduce the possibility of splicing insufficiency as an additional pathomechanism. We conclude that SF mutations are critical events in early leukemogenesis with a large genomic impact, however the prognostic value of SRSF2 and SF3B1 mutations is lost after transformation to AML.
In order to develop new strategies for the treatment of relapsed or refractory acute myeloid leukemia, the German AML Cooperative Group performed a prospective multicenter phase II study to evaluate ...the antileukemic efficacy of aclarubicin 60 mg/m2/day and etoposide 100 mg/m2/day each given for 5 days. Of 37 heavily pretreated evaluable patients (median age 42 years, range 18–81) 15 (40%) achieved a remission after one or two courses of treatment consisting of nine complete (24%) and six partial remissions (16%). Fourteen (38%) cases were non-responders and eight (22%) patients suffered from early deaths. Disease-free survival for patients in remission and overall survival were 3.2 months each. The median duration of critical neutropenia <500/μl was 27 days. the most frequent non-hematologic side-effects were stomatitis (who iii/iv, 48%), infections (40%), nausea/vomiting (26%) and diarrhea (24%). cardiac toxicity was mild. this study suggests a substantial antileukemic efficacy and an acceptable toxicity of aclarubicin in combination with etoposide in heavily pretreated patients with advanced acute myeloid leukemia, and warrants further evaluations in a more favorable stage of the disease.
Background: Many agents in antineoplastic chemotherapy are highly schedule dependent. Therefore, variables such as total dose and also
the area under the curve (AUC) that are schedule insensitive are ...generally insufficient to adequately represent treatment
strength.
Purpose: To establish a descriptor of treatment strength that takes into account the differential contribution of plasma concentrations
( C ) and exposure times ( T ) towards the cytotoxic effect and to investigate whether such a pharmacodynamically weighed descriptor is better correlated
to the clinical effect than conventional variables.
Patients and Methods: The paradigm “ C N × T = constant” (for an isoeffect) incorporates a weighing factor N (concentration coefficient) into the conventional description of the AUC that quantitates the differential contribution of
C and T towards the cytotoxic effect. N was to be numerically derived from a multitude of in vitro isoeffect analyses of the major agents in acute myeloid leukemia (AML) therapy from patient samples ( n = 57).
Results: For cytarabine, N was 0.45, numerically expressing the substantially higher relevance of T versus C for its cytotoxic effect. In a meta-analysis of 49 study arms involving >10,000 patients, neither total dose, dose intensity,
nor AUC was correlated to the clinical effect. However, when AUC was pharmacodynamically weighed ( N -weighed AUC, N -AUC = C 0.45 × T ), this new descriptor was highly significantly correlated to the clinical effect ( P < 0.001).
Conclusion: The N-AUC concept is able to characterize schedule-dependent agents and is the only descriptor of cytarabine treatment strength
actually correlated to the clinical effect in AML.
To detect possible interactions between (-)-formyl-tetrahydrofolic acid (leucovorin, (-)-fTHF) and (+)-formyl-tetrahydrofolic acid ((+)-fTHF) on the plasma and intracellular pharmacokinetics ...following their simultaneous administration.
Plasma levels of (-)-fTHF, (-)-methyl-THF, and (+)-fTHF were determined in samples from four volunteers following the administration of both (-)-fTHF and (+/-)-fTHF and in seven patients during a 5-fluorouracil (5-FU)/fTHF combination chemotherapy. In addition, the intracellular uptake of (14)C-(-)-mTHF in the presence of (+)-mTHF at increasing concentrations was measured in vitro. Analyses were performed using a highly specific high-performance liquid chromatography procedure.
The pharmacokinetic parameters obtained for (-)-fTHF following the administration of (-)-fTHF only were: terminal half-life, 1.2 h; area under the curve, 10 microg. h/ml; maximum concentration, 12 microg/ml; clearance, 305 ml/min; volume of distribution, 19 l. The parameters did not differ significantly as compared with those obtained following the administration of (+/-)-fTHF to both volunteers and patients. There were no differences in the pharmacokinetics of (-)-mTHF or in the protein binding of both substances with the different forms of administration. The intracellular uptake of (14)C-(-)-mTHF did not depend on the presence of (+)-mTHF at either concentration.
These data suggest that (-)-fTHF is not therapeutically superior to (+/-)-fTHF and that the latter is appropriate during combination chemotherapy with 5-FU/fTHF in patients with colorectal cancers.
Idarubicin is the first anthracycline that can be successfully administered via the oral route and thus may facilitate antineoplastic chemotherapy in an improved quality of life. These perspectives ...are somewhat hampered by the large variation in bioavailability between individual patients and the obvious requirement to monitor plasma concentration and area-under-the-curve values (AUC) for an appropriate adjustment of idarubicin dose. In this study we describe the pharmacokinetics of idarubicin and its main metabolite idarubicinol in 12 patients after oral application of 20 mg/m2 idarubicin on 3 consecutive days and demonstrate that the 24 h trough levels show a high correlation with AUC and may thus allow a rapid and easy determination of individual drug concentrations and an appropriate dose adjustment. The average terminal half-life was 30.5 h for idarubicin and 66.9 h for idarubicinol. The AUC for idarubicin and its main metabolite idarubicinol revealed a substantial interpatient variation with AUC values ranging from 25.7 to 114 ng x h/ml (average 58.1 ng x h/ml) for idarubicin and from 109.4-445.2 ng x h/ml (average 287.3 ng x h/ml) for idarubicinol. However, the ratio of idarubicin/idarubicinol differed only two folds from 1:3.7 to 1:7.7 with an average of 1:5.1. Both idarubicin and idarubicinol concentrations were highly reproducible, however, upon measurements after repeated applications within individual patients. Moreover, idarubicinol and idarubicin AUCs showed a good correlation with r = 0.78, indicating that the interindividual variation of idarubicin AUC reflects differences in absorption rather than in metabolism. In order to describe the interindividual bioavailability of idarubicin - represented by the respective AUC - measurement of a single data point with a high correlation with the AUC would be ideal. Our study demonstrates that the 24 h trough level shows such an excellent correlation (r = 0.96) with AUC, making it the perfect candidate for fast estimates of the individual bioavailability in a given patient. On this basis, the longitudinal measurement of the 24 h trough level may allow assessment of the impact of interindividual variations in AUC on clinical outcome and toxicity.
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