Pharmacokinetics and Safety of Atogepant Co-administered with Quinidine Gluconate in Healthy Participants: A Phase 1, Open-Label, Drug-Drug Interaction Study.

Atogepant, an oral calcitonin gene-related peptide receptor antagonist, is approved for the preventive treatment of migraine. Atogepant is a substrate of P-glycoprotein (P-gp), breast cancer resistance protein, organic anion transporting polypeptide transporters, and cytochrome P450 (CYP)3A4 and 2D6. Quinidine is a strong P-gp and CYP2D6 inhibitor. A phase 1 open-label study evaluated the effect of P-gp and CYP2D6 inhibition by quinidine on the pharmacokinetics of atogepant, and the safety and tolerability of atogepant and quinidine gluconate (QG) when co-administered and when given alone in 33 healthy adults. There was no significant change in the atogepant maximum plasma concentration with QG co-administration. The overall systemic exposure, the area under the plasma concentration-time curve (from time 0 to time t or to infinity), of atogepant increased by 25% when co-administered with QG. However, such an increase was not considered clinically relevant. Atogepant did not alter the mean plasma concentration of quinidine at steady state. The incidence of treatment-emergent adverse events (TEAEs) was highest when QG was administered alone (42.4%), which was primarily due to QT prolongation. Most TEAEs reported were mild in severity and resolved within 1-2 days. Co-administration of atogepant with QG did not result in any unexpected tolerability findings in this phase 1 study in healthy participants. The increase in atogepant exposure during QG co-administration could be due to inhibition of CYP2D6 (a minor contributor to atogepant clearance) as well as inhibition of P-gp.

Single-dose Pharmacokinetics of Eluxadoline in Healthy Participants With Normal Renal Function and Participants With Renal Impairment.

Eluxadoline is approved for the treatment of diarrhea-predominant irritable bowel syndrome in the United States. The impact of renal impairment on the pharmacokinetic (PK) parameters of eluxadoline is currently unknown. This phase 1, open-label, parallel-group study evaluated the PK and safety profile of eluxadoline in 8 participants with renal impairment and 8 matched healthy controls. Of the participants with renal impairment, 2 had severe renal impairment (estimated glomerular filtration rate [eGFR] <30 mL/min/1.73 m2 ) and 6 had end-stage renal disease while not yet on dialysis (eGFR <15 mL/min/1.73 m2 ). The primary objective was to assess plasma and urine PKs, and plasma protein binding of eluxadoline. In participants with renal impairment, mean plasma concentrations of eluxadoline were consistently higher compared with matched healthy controls: 1.4-fold higher for mean maximum plasma concentration (Cmax ) and 2.2-fold higher for mean area under the plasma concentration-time curve from time 0 to time t. The median time to Cmax was 2.5 hours in both groups. Although eluxadoline is a locally acting drug with low oral bioavailability, because of the increased systemic exposure in participants with renal impairment as a cautionary measure the lower approved dose of 75 mg twice daily is recommended for individuals with severe renal impairment and end-stage renal disease while not yet on dialysis. Eluxadoline 100 mg single dose was well tolerated in participants with renal impairment and matched healthy controls.

Intestinal Guanylate Cyclase-C mRNA Expression in Duodenum and Colon of Children.

OBJECTIVES: Guanylate cyclase-C (GC-C) agonists, which increase intestinal secretion and accelerate transit, are used to treat chronic constipation and constipation-predominant irritable bowel syndrome and are being evaluated for pediatric use. Prior studies suggest GC-C receptor density may be higher in young children, potentially amplifying GC-C agonism with treatment implications. We aimed to quantitate duodenal and colonic GC-C mRNA expression in children. METHODS: Mucosal biopsies were obtained from subjects aged 6 months to 18 years during clinically indicated upper, that is, esophago-gastro-duodenal, and/or colonic endoscopy. Tissue samples without histologic abnormalities were grouped by subject age (<24 months, 24 months to <6 years, 6 to <12 years, and 12 to <18 years) and analyzed for GC-C mRNA expression by qPCR. The relationship between GC-C mRNA levels and age was modeled using regression analyses. RESULTS: Ninety-nine subjects underwent upper endoscopy/colonoscopy; 93 had evaluable samples. Mean relative GC-C mRNA expression was 2.36 (range 2.21-2.46) for duodenal samples and 1.56 (range 1.22-1.91) for colonic samples. Predicted and observed normalized GC-C mRNA expression in each region were comparable among age groups. Pooled expression by region demonstrated lower expression in colonic versus duodenal samples. CONCLUSIONS: Uniform levels of GC-C mRNA expression were detected in children aged >6 months in the duodenum and >12 months in the colon. Higher expression was observed in all age groups in duodenal versus colonic samples, indicating regional variability in GC-C receptor density. These data are reassuring for further studies of GC-C agonists in children.

Efficacy of Linaclotide in Reducing Abdominal Symptoms of Bloating, Discomfort, and Pain: A Phase 3B Trial Using a Novel Abdominal Scoring System.

INTRODUCTION: Linaclotide improves abdominal pain and constipation in patients with constipation-predominant irritable bowel syndrome (IBS-C). Patients report additional bothersome abdominal symptoms of bloating and discomfort. The intention of this study was to evaluate linaclotide's efficacy in relieving IBS-C-related abdominal symptoms (bloating, discomfort, and pain) using a novel multi-item Abdominal Score (AS). METHODS: Patients with IBS-C with abdominal pain ≥3 (0-10 scale) were randomized to linaclotide 290 µg or placebo daily for 12 weeks. The AS, derived from the Diary for IBS Symptoms-Constipation, is the average of abdominal bloating, discomfort, and pain at their worst (0 = none, 10 = worst possible). The primary end point was overall change from baseline (CFB) in AS. Secondary end points included CFB in 12-week AS evaluated using cumulative distribution function and 6-week/12-week AS responder (AS improvement ≥2 points for ≥6-week/12-week). RESULTS: Overall, 614 patients (mean age 46.7 years; 81% female) were randomized. All prespecified end points showed significant benefit of linaclotide vs placebo. The mean overall CFB AS reduction for linaclotide was -1.9 vs -1.2 for placebo (P < 0.0001); the 6-week/12-week AS responder rate was 40.5% for linaclotide vs 23.4% for placebo (odds ratio = 2.2 [95% confidence interval, 1.55-3.12; P < 0.0001]). Diarrhea was the most common treatment-emergent adverse event (linaclotide = 4.6%, placebo = 1.6%). DISCUSSION: Linaclotide significantly reduced multiple abdominal symptoms important to patients with IBS-C (bloating, discomfort, and pain) compared with placebo, as measured by a novel multi-item AS. The AS, derived from the Diary for IBS Symptoms-Constipation, should be considered for use in future IBS-C clinical studies to measure clinically meaningful improvements beyond traditional end points.

Randomized Trial of 2 Delayed-Release Formulations of Linaclotide in Patients With Irritable Bowel Syndrome With Constipation.

INTRODUCTION: Immediate-release (IR) formulation of linaclotide 290 µg improves abdominal pain and constipation (APC) in patients with irritable bowel syndrome (IBS) with constipation. Delayed-release (DR) formulations were developed on the premise that targeting the ileum (delayed-release formulation 1 [DR1]) or ileocecal junction and cecum (MD-7246, formerly DR2) would modulate linaclotide's secretory effects while preserving pain relief effects. METHODS: This phase 2b study randomized patients with IBS with constipation to placebo or 1 of 7 once-daily linaclotide doses (DR1 30, 100, or 300 µg; MD-7246 30, 100, or 300 µg; or IR 290 µg) for 12 weeks. Key efficacy endpoints were change from baseline in abdominal pain and complete spontaneous bowel movement frequency, and 6/12-week combined APC+1 responder rate. RESULTS: Overall, 532 patients were randomized; mean age was 45.1 years, and most were women (83.3%) and White (64.7%). All linaclotide DR1 and MD-7246 groups experienced greater improvements in abdominal pain from baseline and vs placebo throughout treatment. Linaclotide DR1 and IR led to numerically greater improvements from baseline in complete spontaneous bowel movement frequency and higher APC+1 responder rates compared with placebo; MD-7246 results were similar to placebo. Diarrhea was the most common adverse event with DR1 and IR; rates were similar between MD-7246 and placebo. DISCUSSION: Altering the site of drug delivery in the intestine might uncouple linaclotide's pain relief from secretory effects. Persistent, modest abdominal pain improvement with limited impact on bowel symptom parameters, as seen across MD-7246 doses, warrants further study of MD-7246 as a novel treatment for abdominal pain, regardless of IBS subtype.

Atogepant Has No Clinically Relevant Effects on the Pharmacokinetics of an Ethinyl Estradiol/Levonorgestrel Oral Contraceptive in Healthy Female Participants.

The incidence of migraine is higher among women than men and peaks during the reproductive years, when contraceptive medication use is common. Atogepant, a potent, selective antagonist of the calcitonin gene-related peptide receptor-in development for migraine prevention-is thus likely to be used by women taking oral contraceptives. This phase 1, open-label, single-center, 2-period, fixed-sequence study examined the effect of multiple-dose atogepant 60 mg once daily on the single-dose pharmacokinetics of a combination oral contraceptive, ethinyl estradiol 0.03 mg and levonorgestrel 0.15 mg (EE/LNG), in healthy postmenopausal or oophorectomized women. For participants in period 1, a single dose of EE/LNG was followed by a 7-day washout. In period 2, atogepant was given once daily on days 1-17; an oral dose of EE/LNG was coadministered with atogepant on day 14. Plasma pharmacokinetic parameters for EE and LNG were assessed following administration with and without atogepant. Twenty-six participants aged 45-64 years enrolled; 22 completed the study in accordance with the protocol. The area under the concentration-time curve extrapolated to infinity (AUC0-∞ ) of LNG was increased by 19% when administered with atogepant. Coadministration of atogepant and a single dose of EE/LNG did not substantially alter the pharmacokinetics of EE; the ∼19% increase in plasma AUC0-∞ of LNG is not anticipated to be clinically significant. Overall, atogepant alone and in combination with EE/LNG was generally well tolerated, with no new safety signals identified.

First-in-human phase I trial of two schedules of OSI-930, a novel multikinase inhibitor, incorporating translational proof-of-mechanism studies.

PURPOSE: OSI-930 is a novel, potent, oral small-molecule receptor tyrosine kinase inhibitor, predominantly against VEGF receptors (VEGFR), c-Kit, and platelet-derived growth factor receptors. A phase I trial was undertaken to determine safety, maximum-tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and antitumor activity of OSI-930 in patients with advanced solid tumors. EXPERIMENTAL DESIGN: OSI-930 was administered once or twice a day using a modified accelerated titration design. Pharmacokinetics and plasma soluble VEGFR2 (sVEGFR2) studies were undertaken. Dynamic contrast-enhanced MRI (DCE-MRI) and 2[18F]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) MTD expansion cohorts were conducted. RESULTS: Fifty-eight patients received OSI-930 in 2 schedules; once a day schedule: 12 patients at doses up to 1,600 mg without reaching MTD; twice a day schedule: 46 patients at 400 mg (n = 7), 500 mg (n = 31), and 600 mg (n = 8). Dose-limiting toxicities were observed at 600 mg twice a day (n = 3): G3 rash (n = 2) and G4 γ-glutamyltransferase, establishing the MTD at 500 mg twice a day. Common G1-2 toxicities included fatigue, diarrhea, nausea, and rash. Antitumor responses were seen in 2 patients with advanced ovarian cancer [Response Evaluation Criteria in Solid Tumors (RECIST) partial response (PR) (n = 1); GCIG CA125 response (n = 1)]. Eleven of 19 heavily pretreated imatinib-resistant patients with gastrointestinal stromal tumors achieved RECIST stable disease (median duration: 126 days), with FDG-PET scans showing PRs in 4 of 9 patients. OSI-930 exposure increased with dose; substantial decreases in sVEGFR levels were observed with OSI-930 twice a day doses ≥400 mg, while DCE-MRI responses were shown in 4 of 6 patients. CONCLUSIONS: OSI-930 is safe and well tolerated, with pharmacokinetic-pharmacodynamic data supporting proof-of-mechanism with clinically relevant antitumor activity.

Pharmacokinetics of vilazodone in patients with mild or moderate renal impairment.

BACKGROUND AND OBJECTIVE: In patients with impaired renal function, the pharmacokinetics of a drug may be altered, resulting in decreased renal excretion or metabolism, and altered absorption, plasma protein binding or distribution. Vilazodone is a selective serotonin reuptake inhibitor and 5-HT1A receptor partial agonist approved for the treatment of major depressive disorder. Vilazodone is extensively hepatically metabolized with minimal renal excretion. The primary objective of this study was to assess the pharmacokinetics of a single 20-mg dose of vilazodone in subjects with mild or moderate renal impairment. METHODS: This was a Phase 1, open-label, single-dose study of vilazodone in community-dwelling subjects with renal impairment and in healthy subjects to evaluate the pharmacokinetics of vilazodone in the presence of renal impairment. Thirty-two subjects were enrolled: eight subjects with mild (estimated glomerular filtration rate [est GFR] >50-80 mL/min) renal impairment matched individually by age, sex and body mass index to eight control subjects with normal renal function (est GFR >80 mL/min), and eight subjects with moderate (est GFR ≥30-50 mL/min) renal impairment matched with eight control subjects with normal renal function. Subjects received a single, 20-mg dose of vilazodone and pharmacokinetics, safety and plasma protein binding were assessed for 14 days. The pharmacokinetic parameters calculated were maximum plasma concentration (Cmax), time to maximum plasma concentration, area under the plasma concentration-time curve (AUC) from time zero to 24 h, AUC from time zero to the last measurable concentration, AUC from time zero to infinity estimated by linear trapezoidal rule and extrapolation, oral clearance, terminal elimination rate constant, elimination half-life (t½), free fraction in plasma, apparent free drug clearance, amount of vilazodone recovered in urine 0-96 h following drug administration, percent of dose recovered in urine over 96 h following drug administration, renal clearance and volume of distribution. Safety assessments were adverse events, clinical laboratory test results, 12-lead electrocardiograms and vital signs. RESULTS: Vilazodone pharmacokinetic parameters in renally impaired subjects were variable but not substantially different from healthy controls. Mean values for vilazodone Cmax and AUC were similar among groups. Mean t½ (35.7 and 34.8 h mild and moderate vs. 37.0 and 34.8 h matched controls), total drug clearance (19.9 and 25.1 L/h vs. 26.4 and 26.9 L/h), and mean vilazodone recovery in urine (1.21 % and 0.58 % vs. 0.95 % and 0.81 %) were similar for mild and moderate renally impaired subjects and matched controls with normal renal function. There were no apparent systematic trends in vilazodone pharmacokinetic parameters associated with decreasing renal function. Protein binding was variable (coefficient of variation, 29-65 %) but not substantially different among the three groups, and total drug clearance was not affected. Safety and tolerability of vilazodone were comparable in all groups of subjects. CONCLUSION: This study suggests that systemic exposure of vilazodone is not affected by mild or moderate renal impairment. No dose adjustments are recommended in patients with mild or moderate renal impairment.

An open-label study to describe pharmacokinetic parameters of erlotinib in patients with advanced solid tumors with adequate and moderately impaired hepatic function.

PURPOSE: To compare the pharmacokinetic (PK) parameters of a single dose of erlotinib in cancer patients with moderate hepatic impairment (MHI) to those of cancer patients with adequate hepatic function (AHF). METHODS: Cancer patients with either AHF or MHI were treated with a single 150 mg dose of erlotinib on day 1 only followed by 96 h of plasma sampling for PK assessment. From day 5, patients were allowed to continue daily erlotinib in a maintenance phase. Non-smoking patients were stratified into an AHF cohort (total bilirubin ≤ upper limit of normal [ULN] and ALT/AST ≤ 1.5 X ULN) or a MHI cohort (Child-Pugh score of 7-9). The frequency of adverse events and laboratory changes were assessed. RESULTS: Thirty-six patients, 21 with AHF and 15 with MHI, received at least one dose of erlotinib. The PK of erlotinib was similar between the two cohorts with a median C (max) of 1.09 versus 0.828 µg/mL and corresponding median AUC(0-t ) 29.3 versus 30.5 µg h/mL for the AHF and MHI cohorts, respectively. Adverse events from erlotinib in cancer patients with MHI were consistent with the known safety profile. CONCLUSIONS: The PK and safety profiles of erlotinib in patients with MHI were similar to those with AHF. As a result, a reduced starting dose of erlotinib in patients with MHI is not required and treatment should be guided by patients' tolerability.

A phase I study of OSI-461 in combination with mitoxantrone in patients with advanced solid tumors potentially responsive to mitoxantrone.

PURPOSE: To find the maximum tolerated dose (MTD) of OSI-461 in combination with mitoxantrone in patients with advanced solid tumors. METHODS: This was a Phase I study using cohort dose escalation of OSI-461 dosed orally twice daily in combination with mitoxantrone 12 mg/m(2) given on Day 1 of each 21-day cycle. RESULTS: OSI-461 dose was escalated to 1,000 mg po bid. One patient experienced a dose-limiting toxicity (DLT). Three patients discontinued the study due to adverse events (AE). Two patients (10%) had a partial response, and ten patients (50%) had stable disease as best response. CONCLUSION: The combination of OSI-461 and mitoxantrone was well tolerated. Dose escalation was stopped because of toxicities in a concurrent Phase I trial. The response rate seen in patients with prostate cancer was comparable to response rates seen in trials of mitoxantrone and prednisone alone, and further studies of the combination of OSI-461 and mitoxantrone were not pursued.

Effects of rifampicin (rifampin) on the pharmacokinetics and safety of ambrisentan in healthy subjects: a single-sequence, open-label study.

BACKGROUND: Ambrisentan is a once-daily, endothelin (ET) type A receptor-selective antagonist approved for the treatment of pulmonary arterial hypertension. Ambrisentan is primarily metabolized by glucuronidation and undergoes cytochrome P450 (CYP)-mediated oxidation to a lesser extent. OBJECTIVE: To assess the effects of rifampicin (rifampin), a potent inducer of CYP3A4 and inhibitor of organic anion transporter polypeptides (OATPs), on the steady-state pharmacokinetics, safety and tolerability of ambrisentan. METHODS: This was a 14-day, single-sequence, open-label study that was conducted in 24 healthy adults. Subjects were administered oral doses of ambrisentan (10 mg) once daily on days 1 through 5 and were then co-administered ambrisentan (10 mg) plus rifampicin (600 mg) once daily on days 6 through 13. The steady-state pharmacokinetics of ambrisentan and its oxidative metabolite 4-hydroxymethyl ambrisentan were determined in the absence and presence of repeated administration of rifampicin. The main outcome measure was the analysis of ambrisentan pharmacokinetics (area under the plasma concentration-time curve during a dosage interval [AUC(τ)], maximum plasma drug concentration [C(max)] and minimum plasma drug concentration [C(min)]) for steady-state ambrisentan alone (day 5) as compared with steady-state ambrisentan plus steady-state rifampicin (day 13). Adverse events (AEs), ECG recordings, vital signs and clinical laboratory parameters were monitored throughout the study and at follow-up. RESULTS: A transient increase (+87% [95% CI 79, 95]) in ambrisentan steady-state systemic exposure (AUC(τ)) was observed during the first 2 days of rifampicin co-administration. However, in the presence of steady-state rifampicin, ambrisentan C(max) and AUC(τ) values were similar (+2% [95% CI -7, 12] and -4% [-9, 2], respectively) to those observed for ambrisentan alone. Relative systemic exposure of 4-hydroxymethyl ambrisentan was unaffected by either acute or steady-state rifampicin. No serious AEs or AEs leading to withdrawal were reported and there were no clinically significant changes in vital signs, ECG recordings or clinical laboratory parameters with co-administration of ambrisentan and rifampicin. CONCLUSION: Steady-state rifampicin had no clinically relevant effects on the steady-state pharmacokinetics of ambrisentan. The overall safety profile of ambrisentan was similar in the presence and absence of rifampicin. No dose adjustment of ambrisentan should be required when it is co-administered with rifampicin, a strong inducer of CYP3A4 activity and inhibitor of OATPs.

Effect of steady-state ambrisentan on the pharmacokinetics of a single dose of the oral contraceptive norethindrone (norethisterone) 1 mg/ethinylestradiol 35 microg in healthy subjects: an open-label, single-sequence, single-centre study.

BACKGROUND: Ambrisentan is an oral, once-daily endothelin receptor antagonist (ERA) that is approved for the treatment of pulmonary arterial hypertension (PAH). Pregnancy is not recommended for women of childbearing potential with PAH, due to an increased risk of mortality. Additionally, the ERA class is teratogenic in animal studies. A highly effective method of contraception is therefore strongly recommended for women of childbearing potential who are treated with an ERA for PAH. OBJECTIVE: This study investigated the effect of ambrisentan on the pharmacokinetics (PK) of the oral contraceptive norethindrone (norethisterone) 1 mg/ethinylestradiol 35 microg (NT 1 mg/EE 35 microg). METHODS: The study was an open-label, single-sequence, PK study designed to assess the effect of multiple doses of ambrisentan (Letairis; Volibris) on the PK of a single oral dose of NT 1 mg/EE 35 microg (Ortho-Novum 1/35) in a single clinical research centre in the US. The study included 28 healthy female subjects in general good health, aged 18-45 years, and who had a body mass index of 18.5-29.9 kg/m2. A single oral dose of NT 1 mg/EE 35 microg was administered on day 1. On day 10, following a wash-out period, fasted subjects received once-daily 10 mg doses of ambrisentan for 12 days. On day 22, a single oral dose of NT 1 mg/EE 35 microg and a single 10 mg oral dose of ambrisentan were coadministered; thereafter, subjects continued to receive once-daily oral doses of ambrisentan 10 mg on days 23 through 26. The primary PK endpoints included maximum observed plasma drug concentration (C(max)), time to reach C(max) (t(max)), and the area under the plasma concentration-time curve from time zero to the time of last measurable concentration (AUC(last)). RESULTS: Ethinylestradiol C(max) was slightly decreased (geometric mean ratio [GMR] 91.7%; 90% CI 86.1, 97.8) and AUC(last) was similar (GMR 99.1%; 90% CI 91.0, 107.9) in the presence of ambrisentan compared with NT 1 mg/EE 35 microg. Norethindrone C(max) (GMR 113.2%; 90% CI 102.4, 125.1) and AUC(last) (GMR 112.9%; 90% CI 104.9, 121.6) were slightly increased in the presence of ambrisentan. The 90% CIs were within the pre-defined no-effect boundaries for all PK parameters, except for the C(max) of norethindrone, which was slightly above the upper limit of 125%. No safety concerns were apparent with the coadministration of NT 1 mg/EE 35 microg and ambrisentan. CONCLUSION: No dose adjustment of the oral contraceptive NT 1 mg/EE 35 microg is warranted with the coadministration of ambrisentan.

Overcoming CYP1A1/1A2 mediated induction of metabolism by escalating erlotinib dose in current smokers.

PURPOSE: Cigarette smoking induces CYP1A1/1A2 and is hypothesized to alter erlotinib pharmacokinetics. This study aimed to determine the maximum tolerated dose (MTD) of erlotinib in advanced non-small-cell lung cancer (NSCLC) patients who smoke and compare the pharmacokinetics of erlotinib at the MTD in current smokers with 150 mg. PATIENTS AND METHODS: Cohorts of NSCLC patients currently smoking > or = 10 cigarettes per day for > or = 1 year received escalating doses of erlotinib for 14 days until dose-limiting toxicity (DLT). A separate cohort of patients was then randomly assigned to erlotinib at either MTD or 150 mg daily with pharmacokinetics assessed at day 14. Erlotinib was continued until progression or intolerable toxicity. RESULTS: Four dose levels were evaluated in 22 patients: 200, 250, 300, and 350 mg. DLT was observed in one of six patients at 300 mg (rash) and two of five patients at 350 mg (acneiform dermatitis and fatigue/decreased Eastern Cooperative Oncology Group performance status). Thirty-five patients were randomly assigned to 150 mg or 300 mg. Common adverse events (all grades) were: skin toxicity (150 mg, 29%; 300 mg, 67%), diarrhea (150 mg, 18%; 300 mg, 50%), and fatigue (150 mg, 12%; 300 mg, 17%). Erlotinib exposure was dose-proportional within dose range tested. Median steady-state trough erlotinib plasma concentrations were 0.375 and 1.22 microg/mL for 150 mg and 300 mg, respectively. CONCLUSION: The MTD of erlotinib in NSCLC patients who smoke was 300 mg. Steady-state trough plasma concentrations and incidence of rash and diarrhea in smokers at 300 mg were similar to those in former or never smokers receiving 150 mg in previous studies. The potential benefit of higher erlotinib doses in current smokers warrants further evaluation.

A phase 1 trial of XK469: toxicity profile of a selective topoisomerase IIbeta inhibitor.

PURPOSE: XK469, a member of the quinoxaline family of antitumor agents, is believed to be unique in its ability to selectively target topoisomerase IIbeta. Based on encouraging pre-clinical data, a phase I trial was conducted to determine the dose limiting toxicity (DLT) and the maximum tolerated dose (MTD). METHODS: A 2B accelerated titration schema was employed. XK469 was administered as a 5 or 20 min IV infusion on days 1-5 every 21 days. The starting dose was 9 mg/m(2). Pharmacokinetics (PK) were conducted in cycles 1-3. RESULTS: 22 patients (21 evaluable, mean age: 56 years, median performance status: 1) were enrolled. At dose level 11 (260 mg/m(2)/daily X 5), 1/6 patients experienced a DLT of grade 4 neutropenia. At 346 mg/m(2)/daily X 5, 2/2 patients experienced DLT's with one episode of febrile neutropenia and one grade 3 infection. The MTD was identified as 260 mg/m(2)/day. XK469 peak plasma levels and systemic exposure were proportional to dose indicating linear pharmacokinetics. However, secondary peaks in the PK profiles and a rapid decline in drug level from 23 to 24 h occurred in some patients. Drug infusion in the afternoon followed by dense sampling of levels during the elimination phase supported the hypothesis that the drug was being sequestered. No anti-tumor activity was identified. CONCLUSIONS: Traditional PK sampling designs were inadequate to describe XK469 disposition. XK469 and related structures work through a unique mechanism of action. A further understanding of the specific mechanism of these compounds might uncover a unique avenue for future drug development.

Phase I clinical trial of BMS-247550, a derivative of epothilone B, using accelerated titration 2B design.

PURPOSE: BMS-247550 is a semisynthetic derivative of epothilone B with mechanism of action analogous to paclitaxel. It has shown impressive antitumor activity in preclinical studies including in taxane-resistant models. We conducted a phase I trial, based on accelerated titration "2B" design, of BMS-247550 given as a 1-hour infusion every 3 weeks. EXPERIMENTAL DESIGN: Seventeen patients (M:F, 10:7; median age, 54 years; performance status, 0-2) were treated on the trial. Forty-five cycles (1-9 cycles) of BMS-247550 were given at dosages ranging from 7.4 to 56 mg/m2. All patients received prophylaxis for hypersensitivity reactions, related to Cremophor-EL, with steroids and histamine antagonists. RESULTS: First-course dose-limiting toxicity (DLT) was observed in two of three patients at 56 mg/m2 (neutropenic sepsis, prolonged grade 4 neutropenia) and in one of six patients at 40 mg/m2. Nonhematologic grade 3 to 4 toxicities observed were emesis and fatigue and they occurred only at 56 mg/m2. Grade 1 to 2 peripheral neuropathy was also observed. Other grade 1 to 2 toxicities were myalgias, arthralgias, rash, hand/foot syndrome, and mucositis. AUC and C(max) seemed proportional to the dose and the DLT. Development of neutropenia with BMS-247550 is related to the duration of drug exposure above a threshold. CONCLUSIONS: The maximum tolerated dose (MTD) of BMS-247550 is 40 mg/m2 given every 3 weeks. Neutropenia is the DLT. The accelerated titration "2B" design may help in determining MTD with fewer patients enrolled and more being treated closer to the MTD. However, the accelerated titration design did not seem to shorten the study duration.

Metabolic profile of XK469 (2(R)-[4-(7-chloro-2-quinoxalinyl)oxyphenoxy]-propionic acid; NSC698215) in patients and in vitro: low potential for active or toxic metabolites or for drug-drug interactions.

As part of an ongoing phase 1 study, we studied the excretion of XK469 and its metabolism in patients and in vitro. Five primary metabolites were identified by HPLC/MS/MS. An oxidized product formed by cytosolic aldehyde oxidase was the predominant species both in urine and human hepatocytes in vitro. Conjugates of XK469 with glycine, taurine, and glucuronic acid, as well as the microsomal product, 4-oxo-XK469, were also found in urine and in vitro, but none were major contributors to the mass balance for XK469 elimination. Based upon the relative concentrations circulating in plasma, systemic exposure to parent drug was 100-fold higher than for the metabolites. Thus, both toxicity and efficacy of XK469 are most likely to be produced by the parent molecule, rather than the metabolites. Urinary recovery of parent drug was low (2% of dose in 24 h), partly because of the long half-life of XK469 (approximately 3 days). In addition, the metabolite profile in urine indicates that only 25% of the XK469-derived material was unchanged drug. Thus, urinary excretion was not a major factor in XK469 elimination. Variations in systemic exposure to XK469 will be strongly influenced by factors that alter the activity of aldehyde oxidase, including pharmacogenetics, enzyme inhibition, and enzyme induction, but no specific modifiers have been reported. The multiday half-life of XK469 hampered our ability to obtain a complete mass balance, and the possibility exists that other routes, such as biliary excretion, may also play a substantial role in XK469 disposition.

An in vivo evaluation of docetaxel delivered intratumorally in head and neck squamous cell carcinoma.

OBJECTIVE: To identify activity and biological mechanisms of intratumoral (IT) docetaxel on head and neck squamous cell carcinoma (HNSCC). METHODS: Docetaxel IT therapy was tested in xenograft models of 2 HNSCC lines, HN30 and HN12. The overall and disease-free survival rates, tumor growth, and toxic effects were measured. The pharmacokinetic profiles of docetaxel in plasma and tumor were compared after IT and intravenous (IV) administration. Comparisons between common and supradoses of docetaxel with regard to expression of regulators in the cell cycle, apoptosis, and signal transduction pathways were determined using Western blot analysis. RESULTS: In the HN30 and HN12 xenograft models, IT docetaxel improved overall as well as disease-free survival and reversed tumor growth. The only toxic effects noted were local (alopecia and skin breakdown). Skin breakdown resolved in all cases. At equivalent dosing levels, IT docetaxel achieved a 26-fold higher peak tumor concentration and 24-fold longer tumor exposure than IV treatment. Furthermore, limited plasma exposure was noted with IT docetaxel. Supradose levels of docetaxel produced distinct protein expression patterns for regulators of the cell cycle (cyclins A and B, p21, and p27), apoptosis (cleaved caspase-3 and cleaved PARP), and signal transduction (EGFR, pEGFR, pc-Jun, and pERK) in HNSCC, which supports a distinctive mechanism of action for supradose docetaxel levels. Since levels of cleaved caspase-3 and PARP, markers of apoptosis, were only elevated with lower doses, the observed cell death at supradose levels was probably due to necrosis. CONCLUSIONS: Injections of IT docetaxel at usual and supradoses are associated with a pharmacokinetic profile and biological mechanism distinct from those observed with usual IV doses. It is calculated that IT therapy in men will increase peak concentrations of docetaxel in tumors by 1000-fold over the conventional IV dose used clinically. These preclinical results support further testing of IT docetaxel in HNSCC.

Phase II trial of fenretinide in advanced renal carcinoma.

PURPOSE: Fenretinide, a synthetic form of retinoid, induced apoptosis even in chemotherapy resistant cell lines. A phase II study was hence conducted to evaluate toxicity and efficacy of fenretinide in metastatic renal cancer. METHODS: Eligibility included unresectable or metastatic renal cell carcinoma (RCC), adequate organ function and Zubrod performance status < or =2. Prior immunotherapy and a maximum of one prior chemotherapy regimen were allowed. Fenretinide was administered at a dose of 900 mg/m(2) twice daily orally for 7 days in a 21-day cycle. Toxicity was assessed at the start of each cycle, and response every 2 cycles. RESULTS: Nineteen eligible patients enrolled of which fifteen had visceral/bone metastases. Seventeen patients had prior nephrectomy and 11 had prior immunotherapy. 76 cycles of therapy were delivered. Therapy was very well tolerated with few severe toxicities consisting of thrombosis in 1 individual and grade 3 fatigue, nausea and diarrhea in 1 patient. 5 patients had grade 2 nyctalopia and 3 patients had transient grade 2 visual toxicity. No objective responses were noted. Stable disease was seen in seven of nineteen cases (37%, 90% C.I. 0.21-0.59). Median time to progression was 1.5 months and median duration of stable disease was 5.8 months (90% C.I. 3.0-8.4). Median survival was 10 months. Tumor fenretinide levels were obtained in three patients and were in the lower end of the therapeutic range. CONCLUSION: Fenretinide was well tolerated but demonstrated minimal activity that was consistent with results of intratumoral drug measurements. Strategies are needed that will increase systemic and tumor levels of fenretinide.

Bioavailability and pharmacokinetics of the investigational anticancer agent XK469 (NSC 698215) in rats following oral and intravenous administration.

PURPOSE: To determine the oral bioavailability of R-XK469, a water-soluble investigational anticancer agent undergoing phase I clinical trials as an intravenous product. METHODS: R-XK469 was administered to two groups of catheterized Sprague-Dawley rats via the oral and IV routes at a dose of 10 mg/kg and blood samples were collected at predetermined times. XK469 in plasma samples was quantified using a HPLC method. The pharmacokinetic parameters were computed using WinNonlin 4.0.1 software. RESULTS: The pharmacokinetic parameters of XK469 following oral and IV administrations, respectively, were (mean+/-SD): C(max) 138+/-64 and 404 +/- 355 microg/ml; AUC(0-infinity) 2381 +/- 773 and 2854 +/- 1924 microg h/ml; and elimination half-life (T(1/2)) 12.9 +/- 5.8 and 13.5 +/- 7.8 h T(max) was 2.92+/-1.92 h following oral dosing. Oral R-XK469 was 83% bioavailable. CONCLUSION: Together with the antitumor efficacy of oral XK469 shown in preclinical models and its schedule dependency, these results indicate the promise of developing an oral dosage form of R-XK469 for clinical development.

Pharmacokinetics and tissue distribution of cryptophycin 52 (C-52) epoxide and cryptophycin 55 (C-55) chlorohydrin in mice with subcutaneous tumors.

PURPOSE: To compare the pharmacokinetics and tissue distribution (both normal and tumor) of cryptophycin 52 (C-52) and its putative chlorohydrin prodrug cryptophycin 55 (C-55) in a murine model and to investigate a possible mechanism behind the superior activity of C-55. METHODS: Mammary adenocarcinoma 16/c tumor-bearing mice were treated with an i.v. bolus of 11 mg/kg C-52 or 38 mg/kg C-55 in Cremophor-alcohol. At predetermined time intervals, C-52 and C-55 concentrations in plasma, liver, kidney, small intestine and tumors were measured using a previously described HPLC method. Pharmacokinetic parameters were computed using noncompartmental methods. Tissue (both normal and tumor) to plasma ratios as a function of time were also calculated for comparison. RESULTS: Both C-52 and C-55 were rapidly distributed into different tissues including tumors following i.v. administration. However, the affinities of these compounds towards different tissues were different. Thus, the half-lives (minutes) of C-55 were in the decreasing order liver (725), intestine (494), tumor (206), kidney (62) and plasma (44), whereas the AUC values (microg x min/ml) were in the order tumor (9077), liver (7734), kidney (6790), plasma (2372) and intestine (2234). For C-52, the half-lives (minutes) were in the decreasing order liver (1333), kidney (718), intestine (389), tumor (181) and plasma (35), and the AUC values (microg x min/ml) were in the order kidney (1164), liver (609), intestine (487), plasma (457) and tumor (442). The relative exposures to C-52 after i.v. injection of C-55 were plasma 3.9%, tumor 80.8%, kidney 3.4%, liver 1.1% and intestine 2.8%. Although plasma exposure to C-52 following C-55 administration was relatively small, the use of C-55 to deliver C-52 increased the retention of C-52 and its AUC in tumor compared to direct injection of C-52. Simultaneously, this approach shortened C-52 retention in all normal tissues studied. CONCLUSIONS: The distribution of C-55 and its bioconversion to C-52 in different organs and tumor tissue observed in this study suggest the ability of C-55 to target tumor tissue, creating a depot of C-52 in tumor. Increased C-52 exposure of tumor, with concomitant decreased exposure of normal tissue, is a contributing factor to the superior activity of C-55 versus C-52. However, except in the case of tumor tissue in which 81% of C-55 converts to C-52, only a minor amount of C-55 may serve as a prodrug for C-52, whereas the majority is handled by the biosystem through a different route of elimination. Tissue distribution combined with rate of conversion may be an important determinant of the relative effectiveness of other epoxide-chlorohydrin pairs of cryptophycins.