Phase I clinical, pharmacokinetic, and pharmacodynamic study of KOS-862 (Epothilone D) in patients with advanced solid tumors and lymphoma
Gynecologic Medical Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY, 10021, USA, .Investigational New Drugs (Impact Factor: 2.92). 11/2011; 30(6). DOI: 10.1007/s10637-011-9765-7
Purpose To determine the maximum tolerated dose and safety of the epothilone, KOS-862, in patients with advanced solid tumors or lymphoma. Patients and Methods Patients were treated weekly for 3 out of 4 weeks (Schedule A) or 2 out of 3 weeks (Schedule B) with KOS-862 (16-120 mg/m(2)). Pharmacokinetic (PK) sampling was performed during cycles 1 and 2; pharmacodynamic (PD) assessment for microtubule bundle formation (MTBF) was performed after the 1st dose, only at or above 100 mg/m(2). Results Thirty-two patients were enrolled, and twenty-nine completed ≥1 cycle of therapy. Dose limiting toxicity [DLT] was observed at 120 mg/m(2). PK data were linear from 16 to 100 mg/m(2), with proportional increases in mean C(max) and AUC(tot) as a function of dose. Full PK analysis (mean ± SD) at 100 mg/m(2) revealed the following: half-life (t (½)) = 9.1 ± 2.2 h; volume of distribution (V(z)) = 119 ± 41 L/m(2); clearance (CL) = 9.3 ± 3.2 L/h/m(2). MTBF (n = 9) was seen in 40% of PBMCs within 1 h and in 15% of PBMC at 24-hours post infusion at 100 mg/m(2). Tumor shrinkage (n = 2, lymphoma), stable disease >3 months (n = 5, renal, prostate, oropharynx, cholangiocarcinoma, and Hodgkin lymphoma), and tumor marker reductions (n = 1, colorectal cancer/CEA) were observed. Conclusion KOS-862 was well tolerated with manageable toxicity, favorable PK profile, and the suggestion of clinical activity. The maximum tolerated dose was determined to be 100 mg/m(2) weekly 3-on/1-off. MTBF can be demonstrated in PBMCs of patients exposed to KOS-862.
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- "Epothilone D (KOS-862), effective in breast cancer patients, but it failed to show its efficacy in prostate cancer patients hence it was discontinued in 2007. Hence a more potent analogue of epothilone D, dehydelone was prepared and its antitumor activity was found to be several times more potent than epothilone D. It showed antitumor activity in an MV522 xenograft mouse model and HCT-116 xenograft rat model  . Another example are second and third generation taxanes (ortataxel, carbazitaxel, larotaxel, tesetaxel, TL-310, TPI-287) prepared by modifications in first generation taxanes acting as a non P-gp substrate. "
ABSTRACT: The success of anticancer therapy is limited due to the resistance caused by tumor cells to cytotoxic agents, which interfere with the effectiveness of various chemotherapeutic agents. Several mechanisms for decreased effectiveness of anti-cancer drugs have been examined however the most widely studied mechanism is the efflux of cytotoxic drugs from the cell due to P-gp overexpression. However, the role of P-gp inhibitors in improving chemotherapy is limited due to the existence of other mechanisms of resistance such as activation of glutathione mediated detoxification, blockade of DNA repair, apoptotic pathways, TK signaling pathways and altered tumor microenvironment. Alternative strategies to overcome factors responsible for reduced efficacy of cancer therapy have also been considered such as inhibition of the detoxification system like glutathione, targeting Tks and DNA repair pathways, combination of angiogenic inhibitors, RNAi mediated inhibition of targeted genes etc. Additionally, preventing the onset of resistance can be targeted via siRNA strategy and nanoparticle strategy. In this review, we describe detailed mechanisms involved in decreasing effectiveness of anticancer drugs as well as the strategies used to modulate these mechanisms for effective cancer treatment.
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ABSTRACT: Malignancies are a major cause of morbidity and mortality worldwide. Cancer is a cell disease, characterized by a deviation of the control mechanisms of proliferation and differentiation of cells. Among the treatments available, chemotherapy is often the first choice. Epothilones are a new class of anticancer drugs that act by interacting with cellular microtubules interrupting the proliferation of cancer cells. Many synthetic and semi-synthetic analogues of epothilones have been prepared aiming improvement in effectiveness and tolerability, based on QSAR studies. These analogues have been effective for treatment of tumors resistant to first-line treatments. Six new epothilones are being subjected to clinical trials. Ixabepilone (Ixempra®) was approved by FDA in 2007, patupilone is in phase III clinical trial for ovarian and peritoneum cancer. Sagopilone, desoxiepothilone and KOS-1584 are in phase II clinical trials, for the treatment of recurrent glioblastoma and advanced metastatic breast cancer, metastasic breast cancer and metastatic pulmonary cancer, respectively. desoxiepothilone reached only phase II trials and BMS-310705 reached phase III/IV trials, but was not approved for clinical use due to adverse effects such as neurotoxicity and severe diarrhea, which was dose-limiting. Furthermore, the low t1/2 (40h) in comparison with other class analogues, does not recommend the clinical use of this derivative. Some other synthetized epothilones presented antineoplastic activity in vitro, but are not yet submitted to clinical studies. Neuropathies and diarrhea are adverse effects presented by some substances of this class of anticancer drugs.
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ABSTRACT: A sensitive, accurate and rugged UHPLC–MS/MS method was developed and validated for the quantitation of Epothilone D (EpoD), a microtubule stabilizer in development for treatment of Alzeimer's disease, in rat plasma. The ester group in EpoD can be hydrolyzed by esterases in blood or plasma, which creates a stability concern for the bioanalysis of EpoD. Species differences in the stability of EpoD in plasma were observed. Carboxylesterases were identified as the likely esterases responsible for the hydrolysis of EpoD in plasma ex vivo, and the cause of the species different stability. Phenylmethanesulfonyl fluoride, a carboxylesterase inhibitor, was used to stabilize EpoD in rat blood during sample collection, processing, and storage. A systematic method screening and optimization strategy was used to improve the assay sensitivity and minimize potential bioanalytical risks. The stabilized plasma samples were extracted by liquid–liquid extraction. Chromatographic separation was achieved on an Acquity UPLC BEH Phenyl column with a gradient elution. EpoD and its stable isotope labeled internal standards were detected by positive ion electrospray tandem mass spectrometry. The standard curve, which ranged from 0.100 to 100 ng/mL was fitted to a 1/x2 weighted linear regression model. The intra-assay precision was within ±3.6% CV and inter-assay precision was within ±4.2% CV. The assay accuracy was within ±8.3% of the nominal values. Assay recovery of EpoD was high (∼90%) and matrix effect was minimal (1.02–1.05). EpoD was stable in stabilized rat plasma for at least 30 h at room temperature, 180 days at −20 °C, and following three freeze-thaw cycles. The validated method was successfully applied to sample analysis in toxicology studies.
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