Quantitative analysis of dicer substrate oligonucleotides in mouse liver by ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

A method using multi-mode solid-phase extraction and ultra-high-performance liquid chromatography (UHPLC)-electrospray mass spectrometry was developed to quantify Dicer-substrate small interfering RNA (DsiRNA) directed against the hypoxanthine phosphoribosyltransferase 1 (HPRT1) gene transcript in mouse liver tissue. The oligonucleotides were separated into sense and antisense strands using a UHPLC C(18) column with mobile phases containing 1,1,1,3,3,3-hexafluoro-2-propanol in both water (mobile phase A) and methanol (mobile phase B) with triethylamine as the ion pairing agent at a column temperature of 65°C. The lower limits of detection for the sense and antisense strands were ~1 ng/mg. The dynamic ranges for the sense and antisense strands were 5 ng/mg-1,000 ng/mg and 1 ng/mg-1,000 ng/mg, respectively. The lower limits of quantification for the sense and antisense strands were 5 ng/mg and 1 ng/mg, respectively, each with a relative standard deviation <15% over the range of calibration curve with sufficient precision and accuracy. Oligonucleotides were quantified at different time intervals after intravenous administration of living mice with lipid nanoparticle formulated HPRT1 DsiRNA and were detected as early as 15 min after administration, but not detected beyond the 24 h time point.

RNAi-based treatment for neovascular age-related macular degeneration by Sirna-027.

PURPOSE: To assess the safety, tolerability, pharmacokinetics, and dose-limiting toxicity of single intravitreal injection of Sirna-027, a small interfering RNA targeting vascular endothelial growth factor receptor-1, in patients with choroidal neovascularization (CNV) resulting from neovascular age-related macular degeneration (AMD). Secondary objectives included assessment of anatomic changes in retinal thickness, size of CNV, and changes in visual acuity. DESIGN: Prospective, open-label, single-dose, dose-escalation phase 1 study. METHODS: Twenty-six eyes of 26 patients with a median age of 82 years and CNV resulting from AMD who had previous treatments with other therapies were treated at 2 academic retinal practices. Patients received a single dose of Sirna-027 (100, 200, 400, 800, 1200, or 1600 microg/eye). Blood was sampled for pharmacokinetic analysis at 1, 4, and 24 hours after injection and on day 7. Patients underwent ophthalmic examinations including visual acuity, fluorescein angiography, and optical coherence tomography at screening and days 7, 14, 28, and 84. The main outcome measures were adverse reactions and dose-limiting toxicities. RESULTS: Intravitreal injection of a single dose of Sirna-027 from 100 to 1600 microg was well tolerated in patients with AMD, with no dose-limiting toxicity found. Adverse events were mild to moderate in severity. Adjusted mean foveal thickness decreased within 2 weeks after study treatment. The decrease was most pronounced in the 100- and 200-microg doses. CONCLUSIONS: A single intravitreal dose of Sirna-027 up to 1600 microg/eye was well tolerated in patients with CNV resulting from neovascular AMD that had been refractory to other therapies. Stabilization or improvement in visual acuity and foveal thickness was observed. No dose-response or dose-limiting effects were noted.

Elucidation of potential bortezomib response markers in mutliple myeloma patients.

Liquid chromatography coupled to mass spectrometry (LC/MS) was used to elucidate early biomarkers of bortezomib response in multiple myeloma patients. The change in serum myeloma M-protein level, maintained for a minimum of 6 weeks, is used as one of the main criteria to evaluate patient clinical response to therapy. The objective of this study was to identify biomarkers using LC/MS in order to predict patient response to bortezomib sooner and more accurately compared to serum M-protein levels. The plasma LC/MS biomolecular/biochemical profiles, comprised of thousands of endogenous small molecules, peptides and proteins, were determined for 10 multiple myeloma patients at predose and 24 h after initial dosing with bortezomib. The comparative analysis of the metabolic profiles of non-responders and partial responders provided an opportunity to investigate mechanisms related to disease progression and identify biomarkers related to drug response. The plasma levels of two potential efficacy response markers were significantly more abundant in the non-responsive patients compared to the responders at 24-h postdose. The potential response biomarkers, apolipoprotein C-I and apolipoprotein C-I', were identified by mass spectral analyses and confirmed by authentic protein standards based on MALDI-TOF MS/MS sequencing of proteolytic peptides.

Effect of orlistat on fecal fat, fecal biliary acids, and colonic cell proliferation in obese subjects.

BACKGROUND & AIMS: Orlistat is a weight management agent that selectively inhibits gastrointestinal lipase activity. Because of orlistat's mode of action, increased fecal fat is presented to the colonic mucosa, and fecal bile acid and free fatty acid composition may be altered during treatment. Our aim was to assess the effect of treatment of obese subjects with orlistat 120 mg 3 times a day for 6 weeks on fecal lipid and bile acid parameters and colonic mucosal cell proliferation. METHODS: Twenty-four obese (body mass index, 30-40 kg/m2) but otherwise healthy male and female subjects were enrolled in a single-center, randomized, double-blind, placebo-controlled, parallel-group study. Participants were hospitalized during days 1-3 and 33-42 of treatment and were treated as outpatients for the remaining days. RESULTS: Treatment with orlistat for 6 weeks resulted in significantly greater increases in fecal weight, total fecal fat, and fecal free fatty acids than placebo. Total fecal bile acid amounts decreased slightly with orlistat, and increased significantly with placebo treatment (P < .05 between-group difference). Orlistat did not alter colonic cell proliferation as assessed by the 3 proliferative indices (5-bromo-2-deoxyuridine, whole crypt mitotic count, and proliferating cell nuclear antigen). CONCLUSIONS: Biochemical changes in fecal composition related to the pharmacodynamic mode of action of orlistat are not accompanied by altered colonic cell proliferation, a putative biomarker of colon cancer risk.

Phase I study of bortezomib in refractory or relapsed acute leukemias.

Bortezomib (Velcade, formerly PS-341) is proteasome inhibitor with documented antitumor activity in multiple myeloma and other lymphoid malignancies. We performed a Phase I study to investigate the maximum tolerated dose and dose-limiting toxicity of bortezomib in patients with acute leukemias refractory to or relapsing after prior therapy. Fifteen patients were treated with 0.75 (n = 3), 1.25 (n = 7), or 1.5 (n = 5) mg/m(2) bortezomib administered twice weekly for 4 weeks every 6 weeks. Dose-limiting toxicity included orthostatic hypotension (n = 2), nausea (n = 2), diarrhea (n = 1), and fluid retention (n = 1), all at 1.5 mg/m(2) bortezomib. Proteasome inhibition was dose dependent and reached 68% at 1.5 mg/m(2) bortezomib. Peak inhibition was observed 1 h after treatment and returned to near baseline levels by 72 h after treatment. Incubation of blast cells with bortezomib in vitro showed induction of apoptosis in three of five patients investigated. We conclude that the maximum tolerated dose of bortezomib in patients with acute leukemia is 1.25 mg/m(2), using a twice-weekly for 4 weeks every 6 weeks schedule. The in vitro evidence of antileukemia and transient hematological improvements observed in some patients warrants further investigation of bortezomib in acute leukemias, probably in combination with other agents.

Pharmacokinetic and pharmacodynamic properties of eptifibatide in subjects with normal or impaired renal function.

BACKGROUND: Previous studies of the glycoprotein IIb-IIIa inhibitor eptifibatide have included patients with moderate renal impairment (serum creatinine concentrations, 2.0-4.0 mg/dL). In these patients, adjustment of the standard infusion dose (2.0 microg/kg.min) to 1.0 microg/kg.min was recommended on empiric grounds because approximately 50% of eptifibatide is cleared renally. OBJECTIVE: The present study was designed to assess teh pharmacokinetic and pharmacodynamic properties of eptifibatide in subjects with various levels of creatinine clearance (CrCl), a parameter that is a more accurate indicator of renal function than serum creatinine concentration to determine the appropriate dose adjustment in patients with reduced renal function. A secondary objective was to determine the tolerability of eptifibatide when administered to patients with decreased renal function. METHODS: This open-label study was concluded at 3 US sites experienced in conducting similar studies. Subjects with differing renal function (normal [group 1, CrCl > 80 mL/min], mild renal impairment [group 2, CrCl 51-80 mL/min], moderate renal impairment [group 3, CrCl 30-50 mL/min], or severe renal impairment [group 4, CrCl <30 mL/min]) received a 24-hour eptifibatide infusion of 2.0 microg/kg.min (groups 1, 2, and 3) or 1.0 microg/kg.min (group 4). The primary end point was the eptifibatide steady-state plasma concentration; the secondary end points included inhibition of platelet aggregation and eptifibatide clearance, terminal plasma half-life, and area under the plasma concentration-time curve. In addition to analyses performed for each group, pharmacokinetic models were estimated and eptifibatide clearance was related to CrCl as a continuous variable by linear regression. All adverse events were recorded, with particular attention to bleeding. RESULTS: Thirty-one subjects (21 men, 10 women; mean age, 58.5 years [range, 44-73 years]; mean body weight, 81.6 kg [range, 51.5-105.1 kg]; mean height, 162.9 cm [range, 150-183 cm]) were included in the study. A strong correlation was found between eptifibatide clearance and CrCl. A tree-based analytic model indicated that the optimal discrete break point for the purpose of dose adjustment was a CrCl of 55.85 mL/min, which was rounded to 50 mL/min for practical clinical reasons. In patients with moderate or severe renal impairment (CrCl < or = 50 mL/min), clearance rates and steady-state concentrations of eptifibatide were approximately 50% lower and almost 2-fold higher, respectively, than in patients with normal renal function or mild renal impairment (CrCl > 50 mL/min). Inhibition of platelet aggregation exceeded the clinically significant threshold of 80% in all groups. Five subjects had a mild bleeding event and 4 subjects experienced mild to moderate nonbleeding events, 2 of which were considered drug-related by the investigator. None of the events required intervention. CONCLUSIONS: In this study, moderate to severe renal impairment was associated with an approximately 50% reduction in total eptifibatide clearance and a corresponding doubling of plasma eptifibatide concentration. Based on these findings, in patients with moderately or severely impaired renal function (calculated CrCl < or =50 mL/min) who are scheduled for percutaneous coronary intervention or who have non-ST-segment elevation acute coronary syndromes, it is appropriate to reduce the infusion dose of eptifibatide by 50% (from 2 to 1 microg/kg.min). Because the bolus dose(s) is (are) used to establish the initial targeted plasma eptifibatide concentrations, which are independent of clearance, and given that the volume of distribution did not correlate with renal function, no adjustment of the bolus dose(s) is required.

Phase I trial of the proteasome inhibitor PS-341 in patients with refractory hematologic malignancies.

PURPOSE: To determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacodynamics (PD) of the proteasome inhibitor bortezomib (previously known as PS-341) in patients with refractory hematologic malignancies. PATIENTS AND METHODS: Patients received PS-341 twice weekly for 4 weeks at either 0.40, 1.04, 1.20, or 1.38 mg/m(2), followed by a 2-week rest. The PD of PS-341 was evaluated by measurement of whole blood 20S proteasome activity. RESULTS: Twenty-seven patients received 293 doses of PS-341, including 24 complete cycles. DLTs at doses above the 1.04-mg/m(2) MTD attributed to PS-341 included thrombocytopenia, hyponatremia, hypokalemia, fatigue, and malaise. In three of 10 patients receiving additional therapy, serious reversible adverse events appeared during cycle 2, including one episode of postural hypotension, one systemic hypersensitivity reaction, and grade 4 transaminitis in a patient with hepatitis C and a substantial acetaminophen ingestion. PD studies revealed PS-341 induced 20S proteasome inhibition in a time-dependent manner, and this inhibition was also related to both the dose in milligrams per meter squared, and the absolute dose of PS-341. Among nine fully assessable patients with heavily pretreated plasma cell dyscrasias completing one cycle of therapy, there was one complete response and a reduction in paraprotein levels and/or marrow plasmacytosis in eight others. In addition, one patient with mantle cell lymphoma and another with follicular lymphoma had shrinkage of nodal disease. CONCLUSION: PS-341 was well tolerated at 1.04 mg/m(2) on this dose-intensive schedule, although patients need to be monitored for electrolyte abnormalities and late toxicities. Additional studies are indicated to determine whether incorporation of dose/body surface area yields a superior PD model to dosing without normalization. PS-341 showed activity against refractory multiple myeloma and possibly non-Hodgkin's lymphoma in this study, and merits further investigation in these populations.