The DOT1L inhibitor pinometostat reduces H3K79 methylation and has modest clinical activity in adult acute leukemia.

Pinometostat (EPZ-5676) is a first-in-class small-molecule inhibitor of the histone methyltransferase disrupter of telomeric silencing 1-like (DOT1L). In this phase 1 study, pinometostat was evaluated for safety and efficacy in adult patients with advanced acute leukemias, particularly those involving mixed lineage leukemia (MLL) gene rearrangements (MLL-r) resulting from 11q23 translocations. Fifty-one patients were enrolled into 6 dose-escalation cohorts (n = 26) and 2 expansion cohorts (n = 25) at pinometostat doses of 54 and 90 mg/m2 per day by continuous intravenous infusion in 28-day cycles. Because a maximum tolerated dose was not established in the dose-escalation phase, the expansion doses were selected based on safety and clinical response data combined with pharmacodynamic evidence of reduction in H3K79 methylation during dose escalation. Across all dose levels, plasma pinometostat concentrations increased in an approximately dose-proportional fashion, reaching an apparent steady-state by 4-8 hours after infusion, and rapidly decreased following treatment cessation. The most common adverse events, of any cause, were fatigue (39%), nausea (39%), constipation (35%), and febrile neutropenia (35%). Overall, 2 patients, both with t(11;19), experienced complete remission at 54 mg/m2 per day by continuous intravenous infusion, demonstrating proof of concept for delivering clinically meaningful responses through targeting DOT1L using the single agent pinometostat in MLL-r leukemia patients. Administration of pinometostat was generally safe, with the maximum tolerated dose not being reached, although efficacy as a single agent was modest. This study demonstrates the therapeutic potential for targeting DOT1L in MLL-r leukemia and lays the groundwork for future combination approaches in this patient population. This clinical trial is registered at www.clinicaltrials.gov as NCT01684150.

A phase I open-label study of the safety, tolerability, and pharmacokinetics of pazopanib in combination with irinotecan and cetuximab for relapsed or refractory metastatic colorectal cancer.

BACKGROUND: Pazopanib is a multi-targeted tyrosine kinase inhibitor shown to be clinically active in the treatment of various cancer types. This study aimed to evaluate the maximum tolerated regimen (MTR), safety, and pharmacokinetics of pazopanib in combination with irinotecan and cetuximab in adult patients with relapsed or refractory metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: This was a Phase I, 3 + 3 design, open-label, dose-escalation study (NCT0050943; VEG108925) conducted in sequential cohorts to determine the MTR of pazopanib and irinotecan administered with cetuximab. Twenty-five patients received treatment in three dosing cohorts and were evaluated for safety and tolerability of the combination and pharmacokinetics of individual drugs. RESULTS: The MTR was determined to be 400 mg pazopanib per day orally in combination with 150 mg/m(2) irinotecan biweekly and 250 mg/m(2) cetuximab weekly by infusion. Neutropenia was the main dose-limiting toxicity. Pharmacokinetic results suggested that the overall systemic exposure to SN-38, the active metabolite of irinotecan, was affected by pazopanib to a greater extent than was the systemic exposure to irinotecan itself. CONCLUSIONS: This study provided evidence for the manageable safety profile and feasibility of using the novel triplet combination of pazopanib, irinotecan, and cetuximab in patients with refractory mCRC. Further large-scale Phase II studies are warranted.

Phase I and pharmacokinetic study of pazopanib and lapatinib combination therapy in patients with advanced solid tumors.

This phase I, open-label, dose-escalation study assessed the maximum-tolerated dose, safety, pharmacokinetics, and preliminary antitumor activity of pazopanib plus lapatinib combination therapy in patients with solid tumors. Patients were to take pazopanib and lapatinib orally once daily in a fasting condition. During the escalation phase, pazopanib and lapatinib doses were escalated in serial patient cohorts, and a limited blood sampling scheme was applied for pharmacokinetic evaluation. In the expansion phase, potential pharmacokinetic interaction between pazopanib and lapatinib was evaluated more extensively. Seventy-five patients were treated. Multiple dosing levels were studied, combining pazopanib up to 800 mg/day with lapatinib up to 1,500 mg/day. Dose-limiting toxicities observed included grade 3 neutropenia, fatigue, asymptomatic decline in left ventricular ejection fraction, diarrhea, and liver enzyme elevations. The most common drug-related adverse events were diarrhea, nausea, anorexia, fatigue, vomiting, rash, hair depigmentation, and hypertension. The dose recommended for further evaluation was pazopanib 800 mg plus lapatinib 1,500 mg (paz-800/lap-1500). No clinically significant drug-drug interaction was observed at the paz-400/lap-1000 level. However, at paz-800/lap-1500, an increase in both the AUC0-t and Cmax of pazopanib was observed. Four partial responses were observed in patients with renal cancer (n=2), giant-cell tumor of the bone (n=1), and thyroid cancer (n=1). Stable disease for ≥ 18 weeks was seen in 12 patients. Pazopanib and lapatinib can be administered in combination at their respective single-agent doses with an acceptable safety profile. Further evaluation of the combination will be pursued, exploring both paz-800/lap-1500 and paz-400/lap-1000.

Phase Ib trial of the oral angiogenesis inhibitor pazopanib administered concurrently with erlotinib.

INTRODUCTION: As angiogenic pathways have become important targets for inhibition of tumor growth, we examined the concept of dual pathway blockade by small-molecule tyrosine kinase inhibitors targeting vascular endothelial and epidermal growth factor receptors. METHODS: Escalating doses of pazopanib (400-800 mg once daily [QD]) plus erlotinib (100-150 mg QD) doses were evaluated in cohorts of 3-6 adults with advanced solid tumors. Twelve additional patients were enrolled in an expansion cohort to confirm the maximum tolerated dose (MTD). RESULTS: The MTD, defined during assessment of 20 patients, was pazopanib 600 mg plus erlotinib 150 mg. Two dose-limiting toxicities, rash and elevated liver enzymes, occurred at pazopanib 800 mg and erlotinib 150 mg. Overall, 30 % and 27 % of patients required dose interruption of pazopanib or erlotinib, respectively; 15 % of patients required a dose reduction of erlotinib to manage toxicities. The most common adverse events in patients treated with any dose regimen of pazopanib plus erlotinib (N = 33) were diarrhea, rash, nausea, and decreased appetite. The adverse-event profile of the combination did not appear to differ from that of each compound administered alone. Coadministration of pazopanib 600 mg QD and erlotinib 150 mg QD did not consistently affect the pharmacokinetics of either compound relative to that observed for either compound administered alone. Of 26 patients evaluated for efficacy, 3 (12 %; all non-small-cell lung cancer) had partial response and 10 (38 %) had stable disease. CONCLUSIONS: Concomitant administration of pazopanib 600 mg and erlotinib 150 mg is feasible, with a manageable toxicity profile. These results support further clinical development of the pazopanib-erlotinib combination.

Phase Ib trial of the oral angiogenesis inhibitor pazopanib administered concurrently with pemetrexed in patients with advanced solid tumors.

INTRODUCTION: We sought to define the maximum tolerated dose (MTD) and evaluate the safety, pharmacokinetics, and preliminary clinical activity of pazopanib plus pemetrexed in patients with solid tumors. METHODS: This dose-escalation study used a standard 3 + 3 design to evaluate once daily pazopanib (400-800 mg) plus pemetrexed (400-500 mg/m(2) on Day 1 of each 21-day cycle). Eight additional patients were enrolled into an expansion cohort. RESULTS: Twenty-five patients were enrolled. Pazopanib 800 mg plus pemetrexed 500 mg/m(2) was the MTD. The most common adverse events at all dose levels included fatigue, neutropenia, diarrhea, and thrombocytopenia. The frequencies of non-hematologic adverse events were consistent with those of the individual agents. The rates of all-grade and Grade 4 hematologic toxicities (reversible neutropenia with median duration of 4 days) were higher with the combination regimen than with either monotherapy. Exploratory analyses revealed no association between the plasma levels of 3 biomarkers of vitamin B12 metabolism (cystathionine, homocysteine, and methylmalonic acid) and the risk of Grade 4 neutropenia and Grade 3 febrile neutropenia. Of 20 patients evaluated for efficacy, 2 (10 %) had a partial response. Pazopanib did not affect pemetrexed clearance, but increased pemetrexed maximal concentration by 22 %. In exploratory pharmacogenetic analyses, allelic variants of the VEGFA gene demonstrated weak correlation with development of severe neutropenia. CONCLUSIONS: Concomitant administration of pazopanib 800 mg once daily plus pemetrexed 500 mg/m(2) once every 21 days is feasible, albeit associated with a high frequency of brief, reversible neutropenia. Preliminary activity was observed in non-small-cell lung cancer.

Bioavailability, metabolism and disposition of oral pazopanib in patients with advanced cancer.

1. Pazopanib (Votrient) is an oral tyrosine kinase inhibitor that was recently approved for the treatment of renal cell carcinoma and soft tissue sarcoma. 2. In this two-part study, we investigated the metabolism, disposition of [(14)C]pazopanib, and the oral bioavailability of pazopanib tablets in patients with advanced cancer. 3. In part A, three men each received a single oral dose of [(14)C]pazopanib in suspension (400 mg, 70 µCi). Pazopanib was the predominant drug-related component in circulation. Two metabolites derived from hydroxylation and one from N-demethylation were also circulating, but were minor, each accounting for <5% of plasma radioactivity. Faecal elimination predominated, accounting for 82.2% of the administered radio-dose, with negligible renal elimination (2.6% of dose). Pazopanib was primarily excreted as the unchanged drug in faeces (67% of dose). 4. In part B, seven additional patients received a single intravenous administration of 5 mg pazopanib (day 1) followed by oral administration of 800 mg pazopanib tablet once daily for 26 days (days 3 or 5-28). In the three evaluable patients from part B, pazopanib had a slow plasma clearance and a small volume of distribution. The absolute oral bioavailability of the 800 mg pazopanib tablet ranged from 14% to 39%.

A phase I pharmacokinetic and safety evaluation of oral pazopanib dosing administered as crushed tablet or oral suspension in patients with advanced solid tumors.

Because cancer patients may have difficulty swallowing whole tablets, crushing tablets or ingesting an oral suspension is a practical alternative. This open-label, 2-part, randomized crossover, phase I study evaluated the pharmacokinetics and tolerability of pazopanib administered as a crushed tablet or an oral suspension relative to whole tablet in patients with advanced cancer (Part 1). Patients completing Part 1 were eligible for continuous daily pazopanib 800 mg (Part 2). Administration of a single pazopanib 400 mg crushed tablet increased the area under the curve from 0 to 72 h (AUC((0-72)); 46%) and maximum observed plasma concentration (C(max); ~2-fold), and decreased time to achieve maximum plasma concentration (T(max); ~2 h), indicating increased rate and extent of oral absorption relative to whole-tablet administration. Similarly, a single dose of pazopanib 400 mg suspension increased AUC((0-72)) (33%) and C(max) (29%), and decreased T(max) (1 h). These changes in pharmacokinetic parameters were not associated with increases in the magnitude or duration of short-term (ie, up to 72 h) blood pressure elevation compared with whole-tablet administration.

Phase I study of pazopanib in combination with weekly paclitaxel in patients with advanced solid tumors.

PURPOSE: To evaluate the maximum tolerated regimen (MTR), dose-limiting toxicities, and pharmacokinetics of pazopanib, an oral small-molecule tyrosine kinase inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit, in combination with paclitaxel. PATIENTS AND METHODS: Pazopanib was given daily with weekly paclitaxel on days 1, 8, and 15 every 28 days. Dose levels of pazopanib (mg/day)/paclitaxel (mg/m(2)) were 400/15, 800/15, 800/50, and 800/80. An expanded cohort was enrolled at the MTR. Plasma samples were collected to evaluate the effect of pazopanib, an inhibitor of cytochrome P450 (CYP)3A4, on the pharmacokinetics of paclitaxel, a CYP3A4 and CYP2C8 substrate. RESULTS: Of 26 enrolled patients, 17 were treated at the MTR of 800 mg pazopanib and 80 mg/m(2) paclitaxel. Dose-limiting toxicities included a grade 3 abscess and grade 2 hyperbilirubinemia. Other toxicities included elevated liver transaminases and diarrhea. Six patients (23%) had partial responses and 15 patients (58%) had stable disease. Administration of 800 mg pazopanib resulted in a 14% lower paclitaxel clearance and a 31% higher paclitaxel maximal concentration than with administration of paclitaxel alone at 15, 50, and 80 mg/m(2). At the MTR, coadministration of 800 mg pazopanib and 80 mg/m(2) paclitaxel resulted in a 26% higher geometric mean paclitaxel area under the curve. CONCLUSION: Pazopanib, at a dose of 800 mg daily, can be safely combined with a therapeutic dose of paclitaxel at 80 mg/m(2) when administered on days 1, 8, and 15, every 28 days. The observed greater plasma concentrations of paclitaxel given concurrently with pazopanib suggest that pazopanib is a weak inhibitor of CYP3A4 and CYP2C8.

The absolute bioavailability of oral vinorelbine in patients with solid tumors.

UNLABELLED: Due to advances in the methods used to quantitate vinorelbine, this study was conducted to characterize fully the bioavailability of an oral dosage form of vinorelbine. Twenty-seven eligible patients with solid tumors were enrolled onto this study and were treated in a randomized crossover design to receive either 70 mg/m2 orally or 30 mg/m2 intravenously followed by the alternative treatment one week later. Vinorelbine was administered orally as a soft-gelatin capsule. Pharmacokinetic sampling was carried out for 7 days following each dose. Whole blood vinorelbine concentrations were measured using a sensitive LC/MS/MS method. The data from patients were excluded if they vomited within 3 h after the oral dose. RESULTS: Three subjects were removed from study following the first dose due to safety reasons. Of the remaining 24 subjects, five experienced vomiting within 3 h of oral dosing. Total body clearance calculated from the intravenous dose was 43.65 L/h (+/-10.9) and the terminal half-life was estimated to be 49 h. Using complete data from the remaining 19 subjects, the mean absolute bioavailability of the oral dosage formulation of vinorelbine was calculated to be 33% (+/-18%). In conclusion we have characterized the pharmacokinetics of both orally administered and intravenous vinorelbine over 7 days after administration and have determined the mean oral bioavailability of this oral formulation to be 33%.

A multicenter phase I study of pazopanib in combination with paclitaxel in first-line treatment of patients with advanced solid tumors.

This study was designed to evaluate the safety, pharmacokinetics, and clinical activity of pazopanib combined with paclitaxel to determine the recommended phase II dose in the first-line setting in patients with advanced solid tumors. Patients were enrolled in a 3+3 dose-escalation design to determine the maximum tolerated regimen (MTR) of once daily pazopanib plus paclitaxel administered every 3 weeks at four dose levels (DL1-4). Safety, pharmacokinetics, pharmacogenetics, and disease assessments were performed. Twenty-eight patients received treatment. One patient at DL1 had dose-limiting toxicity (DLT) of elevated hepatic enzymes. After pazopanib discontinuation, liver enzyme concentrations remained high until a concurrent medication, simvastatin, was discontinued. This patient had the defective CYP2C8*3*3 genotype. At DL2, 1 patient had DLT of elevated hepatic enzymes with rash and 1 patient had DLT of rash. The MTR was paclitaxel 150 mg/m(2) plus pazopanib 800 mg. The most common toxicities were alopecia, fatigue, hypertension, nausea, diarrhea, dysgeusia, neutropenia, myalgia, hair color changes, and peripheral neuropathy. Coadministration of pazopanib and paclitaxel resulted in a 38% increase in systemic exposure to paclitaxel, relative to administration of paclitaxel alone, at the MTR. Of the 28 patients treated with the combination, 10 achieved a partial response and 10 achieved stable disease of ≥12 weeks. Pazopanib 800 mg daily plus paclitaxel 150 mg/m(2) every 3 weeks was the recommended phase II dose, with a manageable safety profile, and with clinical activity in both melanoma and non-small cell lung cancer that suggest further evaluation of this combination is warranted.

Assessment of the drug interaction potential and single- and repeat-dose pharmacokinetics of the BRAF inhibitor dabrafenib.

The induction of CYP2C9 by dabrafenib using S-warfarin as a probe and the effects of a CYP3A inhibitor (ketoconazole) and a CYP2C8 inhibitor (gemfibrozil) on dabrafenib pharmacokinetics were evaluated in patients with BRAF V600 mutation-positive tumors. Dabrafenib single- and repeat-dose pharmacokinetics were also evaluated. S-warfarin AUC(0- ∞) decreased 37% and Cmax increased 18% with dabrafenib. Dabrafenib AUC(0- τ) and C(max) increased 71% and 33%, respectively, with ketoconazole. Hydroxy- and desmethyl-dabrafenib AUC(0-τ) increased 82% and 68%, respectively, and AUC for carboxy-dabrafenib decreased 16%. Dabrafenib AUC(0-τ) increased 47%, with no change in C(max), after gemfibrozil co-administration. Gemfibrozil did not affect systemic exposure to dabrafenib metabolites. Single- and repeat-dose dabrafenib pharmacokinetics were consistent with previous reports. All cohorts used the commercial capsules. More-frequent monitoring of international normalized ratios is recommended in patients receiving warfarin during initiation or discontinuation of dabrafenib. Substitution of strong inhibitors or strong inducers of CYP3A or CYP2C8 is recommended during treatment with dabrafenib.

A study to evaluate the pharmacokinetics of oral 5-fluorouracil and eniluracil after concurrent administration to patients with refractory solid tumours and varying degrees of renal impairment (FUMA1005).

BACKGROUND: Eniluracil is an inactivator of dihydropyrimidine dehydrogenase, the first enzyme in the catabolic pathway of 5-fluorouracil (5-FU). Concurrent administration of oral eniluracil with oral 5-FU not only increases the bioavailability of 5-FU, owing to elimination of first-pass metabolism, but can change the route of elimination of 5-FU from hepatic metabolism to renal excretion. An open-label study was performed to determine the effect of renal impairment on the pharmacokinetics of 5-FU in the presence of eniluracil. METHODS: Enrolled in the study were 17 patients with refractory solid tumours (Karnofsky performance status >/=70%; age 31-74 years; 12 male, 5 female). The patients were separated into two groups based upon creatinine clearance (CLCr): group A had "normal" renal function arbitrarily defined as CLCr >/=50 ml/min ( n=8), and group B had moderate renal impairment, i.e. CLCr <50 ml/min ( n=9). Treatment was separated into test and treatment periods. During the test period all patients received eniluracil 50 mg orally on days 1-3 and 5-FU 10 mg/m(2) together with pharmacokinetic measurements. During the treatment period, all patients received eniluracil 50 mg orally on days 1-7 with 5-FU at a standard dose of 20 mg/m(2) for those in group A or a dose individualized according to the pharmacokinetic parameters in the test period for those in group B. RESULTS: The clearance of both eniluracil and 5-FU was decreased in patients with renal impairment compared to those with normal renal function. A linear relationship was observed between 5-FU CL/F and CLCr in patients with renal impairment, but not in those with normal renal function. 5-FU dose modification, on the basis of the test dose pharmacokinetic data for the patients with renal function impairment, accurately resulted in drug exposure in the potentially therapeutic range. Toxicity was not increased. CONCLUSIONS: Eniluracil increases the oral bioavailability of 5-FU and results in a switch from hepatic metabolism to renal elimination. A standard dose of this combination can be administered safely to patients with CLCr >50 ml/min. The combination can also be given to patients with renal impairment using a test dose and pharmacokinetic measurements to predict the appropriate dose of 5-FU. It is expected that sufficient information will be available from this and other studies to allow accurate prediction of the appropriate 5-FU dose modifications required in patients with renal impairment.

Modeling tumor growth kinetics after treatment with pazopanib or placebo in patients with renal cell carcinoma.

PURPOSE: The purpose of this study is to characterize tumor growth kinetics in patients with renal cell carcinoma (RCC) after treatment with pazopanib or placebo and to identify predictive patient-specific covariates. METHODS: Different tumor growth models that included patient-specific covariates were fit to tumor growth data from Phase 2 (n = 220) and Phase 3 (n = 423) clinical trials using nonlinear mixed-effects modeling. Logistic regression was used to determine whether individual model parameters or covariates were related to occurrence of new lesions. RESULTS: A modified Wang model that included a quadratic growth term and a mixture model adequately described the data. Patients in Group 1 (93 %) showed treatment-dependent tumor shrinkage followed by treatment-independent regrowth. Patients in Group 2 (7 %) showed treatment-independent tumor shrinkage that did not regrow. In Group 1, pazopanib 800 mg increased the tumor shrinkage rate by 267 % compared to placebo. Baseline tumor size was dependent on baseline hemoglobin, baseline lactate dehydrogenase, study, and prior nephrectomy. Logistic regression analysis showed that prior radiotherapy, baseline tumor size, tumor shrinkage rate, tumor regrowth rate, study, and treatment (P < 0.01 for all) were all important predictors of new lesions. Patients treated with placebo were approximately twice as likely to develop new lesions than patients treated with pazopanib. CONCLUSIONS: Mathematical modeling of tumor growth kinetics can quantify the effect of anticancer therapies. Pazopanib 800 mg was shown to be an effective treatment for RCC that increased the tumor shrinkage rate by 267 % compared with placebo and reduced the likelihood of developing new lesions.

Bayesian methods for pharmacokinetic/pharmacodynamic modeling of pazopanib-induced increases in blood pressure and transaminases.

Relationships between plasma pazopanib concentrations and the probability of elevations in blood pressure, a marker of vascular endothelial growth factor receptor inhibition, and alanine aminotransferase (ALT) were investigated with logistic regression models. Data from a Phase I dose-escalation study in cancer patients (n = 57) were examined to determine the relationship between steady-state trough plasma pazopanib concentrations (Cτ ) and a clinically significant blood pressure increase, using a Bayesian logistic regression model. Data from 5 monotherapy studies in cancer patients (n = 344) were pooled to investigate the relationship between Cτ and maximum ALT ≥ 3× the upper limit of normal (ULN), using a Bayesian logistic regression model incorporating an asymptote. Both models were fit using WinBUGS. The median (95% credible interval, CrI) Cτ at which the probability of a clinically significant increase in blood pressure was 50% (EC50 ) was 12.3 µg/mL (6.12, 18.4). The median (95% CrI) EC50 for the maximum probability of ALT ≥ 3 × ULN was 15.4 µg/mL (3.8, 41.2) and the median (95% CrI) maximum probability of ALT ≥ 3 × ULN was 21% (14.5, 43.1). Results suggest that dose adjustments could be useful in managing the potential for hepatotoxicity.

Initial exploration of oral pazopanib in healthy participants and patients with age-related macular degeneration.

IMPORTANCE: Neovascular age-related macular degeneration (AMD) is managed with intravitreal anti-vascular endothelial growth factor therapy; however, the burden of care is high and alternate approaches could be beneficial. OBJECTIVE To identify an acceptable dose of oral pazopanib for investigation in AMD. DESIGN, SETTING, AND PARTICIPANTS: Fourteen-day, placebo-controlled, dose-rising study in 72 healthy participants and 28-day phase 2a open-label study in 15 patients with subfoveal choroidal neovascularization secondary to AMD at a clinical unit for healthy participants and outpatient for patients with AMD. INTERVENTION: Oral pazopanib tablets, 5 to 30 mg daily (healthy participants) and 15 mg daily (patients with AMD). MAIN OUTCOMES AND MEASURES: Safety, pharmacokinetics, best-corrected visual acuity, central retinal lesion thickness, and central retinal thickness at day 29. RESULTS: Oral pazopanib up to 30 mg daily in healthy participants and 15 mg daily in patients with AMD was well tolerated. Six of 15 patients received rescue therapy before day 29; all had the CFH Y402H CC "high-risk" genotype for AMD. Nine patients completed the study without rescue with improvements from baseline in best-corrected visual acuity (8 Early Treatment Diabetic Retinopathy Study letters), central retinal lesion thickness (-50.94 µm), and central retinal thickness (-50.28 µm). There was a trend for association between the CFH Y402H T allele ("low risk" for AMD, n = 6) and improvement. CONCLUSIONS AND RELEVANCE: Oral pazopanib (15 mg daily) was well tolerated and resulted in improvements in mean best-corrected visual acuity, central retinal lesion thickness, and central retinal thickness at day 29 in a per-protocol, nonrescued AMD population (n = 9). It is postulated that CFH Y402H genotype may help predict which patients respond to pazopanib. The size and length limitations of this study warrant further investigation to determine if oral pazopanib may be an appropriate treatment for a subset of neovascular patients with AMD or as an adjunct to standard of care. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01051700 and NCT01154062.

Effects of ketoconazole and esomeprazole on the pharmacokinetics of pazopanib in patients with solid tumors.

PURPOSE: The metabolism of pazopanib is primarily mediated by CYP3A4. The solubility of pazopanib is pH-dependent, and an elevated gastric pH may decrease its bioavailability. This study evaluated the effect of a potent CYP3A4 inhibitor, ketoconazole, and the proton pump inhibitor esomeprazole on the pharmacokinetics and safety of pazopanib and its metabolites. METHODS: In Arm A, patients received pazopanib 400 mg alone once daily for 7 days followed by pazopanib 400 mg plus ketoconazole 400 mg once daily for 5 days. In Arm B, patients received pazopanib 800 mg once daily for 7 days, followed by pazopanib 800 mg plus esomeprazole 40 mg once daily for 5 days, and then pazopanib alone on the last day. RESULTS: Arm A enrolled 21 patients. In the presence of ketoconazole, mean area under the plasma concentration-time curve 24 h post-dose (AUC(0-24)) and mean maximum observed concentration (C max) of pazopanib increased by 66 and 45 %, respectively; mean AUC(0-24) and C max for pazopanib metabolites were lower or remained unchanged. Arm B enrolled 13 patients. In the presence of esomeprazole, mean pazopanib AUC(0-24) and C max decreased by 40 and 42 %, respectively; mean values of those parameters for metabolites of pazopanib also decreased. CONCLUSIONS: Concomitant use of pazopanib with a strong CYP3A4 inhibitor should be avoided. If coadministration is necessary, pazopanib should be reduced to 400 mg. Concomitant use of pazopanib and proton pump inhibitors should also be avoided. Alternative dosing regimens that do not increase gastric pH at the time of pazopanib dosing should be considered.

A phase I/II trial of pazopanib in combination with lapatinib in adult patients with relapsed malignant glioma.

PURPOSE: Increased mitogenic signaling and angiogenesis, frequently facilitated by somatic activation of EGF receptor (EGFR; ErbB1) and/or loss of PTEN, and VEGF overexpression, respectively, drive malignant glioma growth. We hypothesized that patients with recurrent glioblastoma would exhibit differential antitumor benefit based on tumor PTEN/EGFRvIII status when treated with the antiangiogenic agent pazopanib and the ErbB inhibitor lapatinib. EXPERIMENTAL DESIGN: A phase II study evaluated the antitumor activity of pazopanib 400 mg/d plus lapatinib 1,000 mg/d in patients with grade 4 malignant glioma and known PTEN/EGFRvIII status not receiving enzyme-inducing anticonvulsants (EIAC). The phase II study used a two-stage Green-Dahlberg design for futility. An independent, parallel phase I component determined the maximum-tolerated regimen (MTR) of pazopanib and lapatinib in patients with grade 3/4 glioma receiving EIACs. RESULTS: The six-month progression-free survival (PFS) rates in phase II (n = 41) were 0% and 15% in the PTEN/EGFRvIII-positive and PTEN/EGFRvIII-negative cohorts, respectively, leading to early termination. Two patients (5%) had a partial response and 14 patients (34%) had stable disease lasting 8 or more weeks. In phase I (n = 34), the MTR was not reached. On the basis of pharmacokinetic and safety review, a regimen of pazopanib 600 mg plus lapatinib 1,000 mg, each twice daily, was considered safe. Concomitant EIACs reduced exposure to pazopanib and lapatinib. CONCLUSIONS: The antitumor activity of this combination at the phase II dose tested was limited. Pharmacokinetic data indicated that exposure to lapatinib was subtherapeutic in the phase II evaluation. Evaluation of intratumoral drug delivery and activity may be essential for hypothesis-testing trials with targeted agents in malignant glioma.

A randomized, double-blind, placebo-controlled study to evaluate the effect of repeated oral doses of pazopanib on cardiac conduction in patients with solid tumors.

PURPOSE: As tyrosine kinase inhibitors have been associated with cardiotoxicity, we evaluated the effect of pazopanib, an inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit, on electrocardiographic parameters in patients with cancer. METHODS: This double-blind, placebo-controlled, parallel-group study randomized patients (N = 96) to moxifloxacin (positive control) or placebo on Day 1 followed by pazopanib or placebo 800 mg/day (fasted) on Days 2-8 and 1,600 mg (with food) on Day 9. Treatment effects were evaluated by baseline-adjusted, time-matched, serial Holter electrocardiograms. RESULTS: Sixty-five patients were evaluable for preplanned analyses. On Day 1, the maximum mean difference in baseline-adjusted, time-matched Fridericia-corrected QT (QTcF) interval in moxifloxacin-treated patients versus placebo was 10.6 ms (90% confidence interval [CI]: 4.2, 17.0). The administration scheme increased plasma pazopanib concentrations approximately 1.3- to 1.4-fold versus the recommended 800 mg once-daily dose. Pazopanib caused clinically significant increases from baseline in blood pressure, an anticipated class effect, and an unexpected reduction in heart rate from baseline that correlated with pazopanib exposure. On Day 9, the maximum mean difference in baseline-adjusted, time-matched QTcF interval in pazopanib-treated patients versus placebo was 4.4 ms (90% CI: -2.4, 11.2). Mixed-effects modeling indicated no significant concentration-dependent effect of pazopanib or its metabolites on QTcF interval. CONCLUSIONS: Pazopanib as administered in this study achieved supratherapeutic concentrations, produced a concentration-dependent decrease in heart rate, and caused a small, concentration-independent prolongation of the QTcF interval.

Phase I study of pazopanib in patients with advanced solid tumors and hepatic dysfunction: a National Cancer Institute Organ Dysfunction Working Group study.

PURPOSE: Pazopanib is a potent, multitargeted receptor tyrosine kinase inhibitor; however, there is limited information regarding the effects of liver function on pazopanib metabolism and pharmacokinetics. The objective of this study was to establish the maximum-tolerated dose (MTD) and pharmacokinetic profile of pazopanib in patients with varying degrees of hepatic dysfunction. EXPERIMENTAL DESIGN: Patients with any solid tumors or lymphoma were stratified into four groups based on the degree of hepatic dysfunction according to the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria. Pazopanib was given orally once a day on a 21-day cycle. A modified 3+3 design was used. RESULTS: Ninety-eight patients were enrolled. Patients in the mild group tolerated 800 mg per day. The moderate and severe groups tolerated 200 mg per day. Pharmacokinetic data in the mild group were similar to the data in the normal group. Comparison of the median Cmax and area under the curve [AUC(0-24)] in the moderate or severe groups at 200 mg per day to the values in the normal and mild groups at 800 mg per day indicated less than dose-proportional systemic exposures in patients with moderate and severe hepatic impairment. This suggests that the lower maximum-tolerated dose in the moderate and severe group is not due to a decrease in drug clearance or alteration in the proportion of metabolites. CONCLUSIONS: In patients with mild liver dysfunction, pazopanib is well tolerated at the Food and Drug Administration (FDA)-approved dose of 800 mg per day. Patients with moderate and severe liver dysfunction tolerated 200 mg per day.

Phase I study of pazopanib in combination with paclitaxel and carboplatin given every 21 days in patients with advanced solid tumors.

Several phase III trials have shown that the addition of an antiangiogenic agent to conventional chemotherapy can improve clinical benefit in patients with advanced solid tumors. This study examined the feasibility of combining pazopanib (Votrient), an oral antiangiogenic agent, with paclitaxel and carboplatin. This 3 + 3 dose-escalation phase I study evaluated the maximum-tolerated regimen (MTR) of daily pazopanib in combination with paclitaxel 175 mg/m(2) and carboplatin [dosed at area under the curve (AUC) 5 or 6] given every 21 days in patients with advanced solid tumors. Plasma samples were collected to evaluate the effect of pazopanib on the pharmacokinetics of paclitaxel and carboplatin. Thirty-four patients were enrolled. The MTR was paclitaxel 175 mg/m(2) and carboplatin AUC5 with pazopanib 200 mg. The most common dose-limiting toxicities were neutropenia and thrombocytopenia. Two patients with esophageal cancer had a complete response and four patients, one each with breast, small-cell lung, pancreatic, and gastroesophageal junction cancer, had partial responses. Pazopanib at 200 mg increased paclitaxel maximal concentration (C(max)) by 43% and carboplatin (AUC5 or AUC6) C(max) by 54%. Paclitaxel and carboplatin given every 21 days at standard doses was not feasible in combination with the monotherapy pazopanib dose of 800 mg daily because of dose-limiting myelosuppression. Coadministration of pazopanib increased exposure to paclitaxel and carboplatin and likely contributed to this effect. Given the antitumor activity of this regimen, further studies are underway to determine a clinically tolerable schedule of pazopanib with paclitaxel and carboplatin.