Publications by authors named "Steve Eppler"

11 Publications

  • Page 1 of 1

Phase I study of the anti-α5β1 monoclonal antibody MINT1526A with or without bevacizumab in patients with advanced solid tumors.

Cancer Chemother Pharmacol 2018 08 15;82(2):339-351. Epub 2018 Jun 15.

California Cancer Associates for Research & Excellence, Encinitas, CA, USA.

Purpose: MINT1526A is a monoclonal antibody that blocks the interaction of integrin alpha 5 beta 1 (α5β1) with its extracellular matrix ligands. This phase I study evaluated the safety and pharmacokinetics of MINT1526A with or without bevacizumab in patients with advanced solid tumors.

Methods: MINT1526A was administered every 3 weeks (Q3W) as monotherapy (arm 1) or in combination with bevacizumab 15 mg/kg, Q3W (arm 2). Each arm included a 3 + 3 dose-escalation stage and a dose-expansion stage.

Results: Twenty-four patients were enrolled in arm 1 (dose range 2-30 mg/kg) and 30 patients were enrolled in arm 2 (dose range 3-15 mg/kg). Monocyte α5β1 receptor occupancy was saturated at a dose of 15 mg/kg. No dose-limiting toxicities were observed, and the maximum tolerated dose was not reached in either arm. The most common adverse events, regardless of causality, included abdominal pain (25%), diarrhea (25%), nausea (21%), vomiting (21%), and fatigue (21%) in arm 1 and nausea (40%), fatigue (33%), vomiting (30%), dehydration (30%), headache (30%), and hypertension (30%) in arm 2. No grade ≥ 3 bleeding events were observed in either arm. No confirmed partial responses (PR) were observed in arm 1. In arm 2, one patient with thymic carcinoma experienced a confirmed PR and two patients with hepatocellular carcinoma (HCC) experienced durable minor radiographic responses.

Conclusions: MINT1526A, with or without bevacizumab, was well-tolerated. Preliminary evidence of combination efficacy, including in patients with HCC, was observed, but cannot be distinguished from bevacizumab monotherapy in this phase I study.
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August 2018

Evaluation of Cytochrome P450 3A4-Mediated Drug-Drug Interaction Potential for Cobimetinib Using Physiologically Based Pharmacokinetic Modeling and Simulation.

Clin Pharmacokinet 2016 11;55(11):1435-1445

Clinical Pharmacology, Genentech, Inc., South San Francisco, CA, USA.

Background And Objectives: Cobimetinib is eliminated mainly through cytochrome P450 (CYP) 3A4-mediated hepatic metabolism in humans. A clinical drug-drug interaction (DDI) study with the potent CYP3A4 inhibitor itraconazole resulted in an approximately sevenfold increase in cobimetinib exposure. The DDI risk for cobimetinib with other CYP3A4 inhibitors and inducers needs to be assessed in order to provide dosing instructions.

Methods: A physiologically based pharmacokinetic (PBPK) model was developed for cobimetinib using in vitro data. It was then optimized and verified using clinical pharmacokinetic data and itraconazole-cobimetinib DDI data. The contribution of CYP3A4 to the clearance of cobimetinib in humans was confirmed using sensitivity analysis in a retrospective simulation of itraconazole-cobimetinib DDI data. The verified PBPK model was then used to predict the effect of other CYP3A4 inhibitors and inducers on cobimetinib pharmacokinetics.

Results: The PBPK model described cobimetinib pharmacokinetic profiles after both intravenous and oral administration of cobimetinib well and accurately simulated the itraconazole-cobimetinib DDI. Sensitivity analysis suggested that CYP3A4 contributes ~78 % of the total clearance of cobimetinib. The PBPK model predicted no change in cobimetinib exposure (area under the plasma concentration-time curve, AUC) with the weak CYP3A inhibitor fluvoxamine and a three to fourfold increase with the moderate CYP3A inhibitors, erythromycin and diltiazem. Similarly, cobimetinib exposure in the presence of strong (rifampicin) and moderate (efavirenz) CYP3A inducers was predicted to decrease by 83 and 72 %, respectively.

Conclusion: This study demonstrates the value of using PBPK simulation to assess the clinical DDI risk inorder to provide dosing instructions with other CYP3A4 perpetrators.
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November 2016

Determination of cobimetinib in human plasma using protein precipitation extraction and high-performance liquid chromatography coupled to mass spectrometry.

J Chromatogr B Analyt Technol Biomed Life Sci 2014 Dec 7;972:117-23. Epub 2014 Oct 7.

Drug Metabolism and Pharmacokinetics, Genentech, South San Francisco, CA 94080, United States.

Inhibition of MAP/ERK kinase (MEK) is a promising strategy to control the growth of tumors that are dependent on aberrant signaling in the MEK pathway. Cobimetinib (GDC-0973) (S)-[3,4-Difluoro-2-(2-fluoro-4-iodo-phenylamino)-phenyl]-((S)-3-hydroxy-3-piperidin-2-yl-azetidin-1-yl)-methanone) inhibits proliferation of a variety of human tumor cell lines by inhibiting MEK1 and MEK2. A specific high performance liquid chromatography-mass spectrometric assay was developed and validated for the determination of cobimetinib in human plasma. The overall mean recovery using protein precipitation extraction with acetonitrile was found to be 54.1%. The calibration curve was ranged from 0.20 to 100ng/mL. The LLOQ was sensitive enough to detect terminal phase concentrations of the drug. The intra- and inter-assay precision (%CV) was within 10.3% and 9.5% for cobimetinib. The assay accuracy (%RE) was within ±13.7% of the nominal concentration values for cobimetinib with the normal analytical QCs. The developed assay was successfully used to analyze the human plasma samples (for pharmacokinetic analysis) from clinical trials.
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December 2014

Phase I dose-escalation study of onartuzumab as a single agent and in combination with bevacizumab in patients with advanced solid malignancies.

Clin Cancer Res 2014 Mar 3;20(6):1666-75. Epub 2014 Feb 3.

Authors' Affiliations: Section of Hematology/Oncology, Department of Medicine, The University of Chicago, Chicago, Illinois; Genentech, Inc., South San Francisco, California; and Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, New Jersey.

Purpose: This first-in-human study evaluated the safety, immunogenicity, pharmacokinetics, and antitumor activity of onartuzumab, a monovalent antibody against the receptor tyrosine kinase MET.

Experimental Design: This 3+3 dose-escalation study comprised three stages: (i) phase Ia dose escalation of onartuzumab at doses of 1, 4, 10, 20, and 30 mg/kg intravenously every 3 weeks; (ii) phase Ia cohort expansion at the recommended phase II dose (RP2D) of 15 mg/kg; and (iii) phase Ib dose escalation of onartuzumab at 10 and 15 mg/kg in combination with bevacizumab (15 mg/kg intravenously every 3 weeks). Serum samples were collected for evaluation of pharmacokinetics, potential pharmacodynamic markers, and antitherapeutic antibodies.

Results: Thirty-four patients with solid tumors were treated in phase Ia and 9 in phase Ib. Onartuzumab was generally well tolerated at all dose levels evaluated; the maximum tolerated dose was not reached. The most frequent drug-related adverse events included fatigue, peripheral edema, nausea, and hypoalbuminemia. In the phase Ib cohort, onartuzumab at the RP2D was combined with bevacizumab and no dose-limiting toxicities were seen. Onartuzumab showed linear pharmacokinetics in the dose range from 4 to 30 mg/kg. The half-life was approximately 8 to 12 days. There were no apparent pharmacokinetic interactions between onartuzumab and bevacizumab, and antitherapeutic antibodies did not seem to affect the safety or pharmacokinetics of onartuzumab. A patient with gastric carcinoma in the 20-mg/kg dose cohort achieved a durable complete response for nearly 2 years.

Conclusions: Onartuzumab was generally well tolerated as a single agent and in combination with bevacizumab in patients with solid tumors.
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March 2014

Absolute bioavailability and effect of formulation change, food, or elevated pH with rabeprazole on cobimetinib absorption in healthy subjects.

Mol Pharm 2013 Nov 30;10(11):4046-54. Epub 2013 Sep 30.

Genentech, Inc. , 1 DNA Way, South San Francisco, California, 94080, United States.

Cobimetinib is a potent and highly selective inhibitor of MEK1/2. Since cobimetinib exhibited absorption variability in cancer patients, a series of single-dose studies in healthy subjects were conducted to determine absolute bioavailability and elucidate potential effects of formulation, food, and elevated gastric pH on cobimetinib bioavailability. Three crossover trials were performed with a 20 mg cobimetinib oral dose: absolute bioavailability using a 2 mg intravenous infusion (n = 13), relative bioavailability of tablets versus capsules and food effect (n = 20), and drug interaction with a proton pump inhibitor (20 mg of rabeprazole daily for 5 days prior to cobimetinib administration; n = 20). Absolute bioavailability of cobimetinib was 46.2% (24.2, CV %), likely due to metabolism rather than incomplete absorption. The mean systemic clearance of cobimetinib was low (11.7 L/h [28.2, CV %]). Administration of cobimetinib tablets with a high-fat meal delayed drug absorption (prolonged tmax) but had no statistically significant effect on cobimetinib exposure (Cmax and AUC0-∞). Tablet and capsule formulations of cobimetinib showed comparable exposures. Cobimetinib exhibited delayed absorption (tmax) in the presence of rabeprazole, with no statistically significant effects on drug exposure (Cmax and AUC0-∞) in the fasted state. In conclusion, cobimetinib oral absorption was not affected by change in formulation, food, or elevated gastric pH.
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November 2013

Death receptor 5 agonistic antibody PRO95780: preclinical pharmacokinetics and concentration-effect relationship support clinical dose and regimen selection.

Cancer Chemother Pharmacol 2013 Aug 16;72(2):405-15. Epub 2013 Jun 16.

Department of Pharmacokinetic and Pharmacodynamic Sciences, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Purpose: PRO95780, a human monoclonal antibody (mAb) against death receptor 5 (DR5/TRAIL-R2/TNFRSF10B), was developed for the treatment for cancer. Our objective was to characterize pharmacokinetics (PK) in mice, rats, and cynomolgus monkeys and concentration-effect relationships of PRO95780 in xenograft mouse models of human cancers; this would guide the selection of dose and regimen for clinical trials.

Methods: The PK profiles were determined in mice, rats, and cynomolgus monkeys. Three xenograft models with a wide range of in vitro sensitivities to PRO95780 were selected for efficacy studies. Tumoristatic serum concentrations (TSCs) were determined using PK/pharmacodynamic (PD) modeling with tumor growth as a PD endpoint. A species-invariant time PK scaling method was employed to estimate disposition in humans using PK data in cynomolgus monkeys. Furthermore, the predicted human PK parameters were used to estimate dose and regimen to achieve TSC observed in mice at the steady-state trough concentrations (C trough ss) in the clinic.

Results: Linear PK was observed across species. A serum concentration of 22 μg/mL was identified to be the target TSC in mice. A dose of 10 mg/kg administered once every 2 weeks (Q2W) was predicted to achieve a TSC at C trough ss in 95 % of patients.

Conclusions: PRO95780 has linear PK in mice, rats, and monkeys. Estimated TSCs varied among different xenograft models. A projected target dose in humans is achievable for Q2W administration within the dose range used for other commercial mAbs.
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August 2013

Pharmacokinetics of ranibizumab in patients with neovascular age-related macular degeneration: a population approach.

Invest Ophthalmol Vis Sci 2013 Mar 5;54(3):1616-24. Epub 2013 Mar 5.

Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Purpose: To characterize ranibizumab pharmacokinetics in patients with AMD.

Methods: A population approach of nonlinear mixed-effect pharmacokinetic modeling based on concentration-time data from 2993 serum samples from 674 AMD patients enrolled in 5 phase 1 to 3 clinical trials of single or multiple intravitreal (ITV) doses of ranibizumab (0.3-2.0 mg/eye) administered biweekly or monthly for up to 24 months.


Conclusions: Systemic exposure to ranibizumab after ITV injection was very low due to elimination on reaching systemic circulation from the vitreous. Population pharmacokinetic analysis of data from a representative sample of AMD patients did not identify clinically significant sources or correlates of variability in ranibizumab exposure. ( numbers, NCT00056836, NCT00056823.).
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March 2013

Developmental immunotoxicology assessment of rituximab in cynomolgus monkeys.

Toxicol Sci 2011 Jan 11;119(1):116-25. Epub 2010 Oct 11.

Safety Assessment, Genentech Inc., 1 DNA Way, South San Francisco, California 94080, USA.

Rituximab is a chimeric murine/human-engineered immunoglobulin (Ig) G1 anti-CD20 monoclonal antibody, selectively depleting CD20-expressing cells in peripheral blood and lymphoid tissues. As part of the rituximab registration-enabling program for rheumatoid arthritis, cynomolgus monkey embryo-fetal development and pre- and postnatal developmental toxicity studies were performed. In both studies, female cynomolgus monkeys were administered rituximab iv at doses of 0/0, 15/20, 37.5/50, and 75/100 mg/kg (loading dose/study dose) from gestation day (GD) 20 to 50 for the embryo-fetal development study and GD 20 to postpartum (pp) day 28 for the pre- and postnatal study. In the embryo-fetal development study, although maternal dosing ended during the first trimester at GD 50, placental transfer of rituximab to fetuses was demonstrated at GD 100. Consequently, fetuses demonstrated B-cell depletion in lymphoid tissues at GD 100. Repletion of B cells was demonstrated in infants in a follow-up pre- and postnatal study following fetal and neonatal exposure. In the pre- and postnatal study, despite B-cell depletion, there was no significant functional consequence on the infant's ability to mount T-cell-dependent antibody responses following vaccination or antigenic challenge. Overall, rituximab was well tolerated at maximum feasible doses up to 100 mg/kg in pregnant cynomolgus monkeys and their infants after exposure from the period of organogenesis throughout pregnancy, parturition, and postnatal development. Importantly, the preclinical data have been concordant with the clinical data in children for cases where rituximab was administered during pregnancy.
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January 2011

Clinical pharmacokinetics of bevacizumab in patients with solid tumors.

Cancer Chemother Pharmacol 2008 Oct 19;62(5):779-86. Epub 2008 Jan 19.

Department of Pharmacokinetic and Pharmacodynamic Sciences, Genentech, Inc., 1 DNA Way, MS70, South San Francisco, CA 94080, USA.

Objective: To characterize the population pharmacokinetics of bevacizumab and the influence of demographic factors, disease severity, and concomitantly used chemotherapy agents on it's pharmacokinetic behavior.

Patients And Methods: Data from eight clinical trials with bevacizumab administered by intravenous infusion were included. A total of 4,629 bevacizumab concentrations from 491 patients with solid tumors, who received bevacizumab doses ranging from 1 to 20 mg/kg at a dosing frequency ranging from weekly to every 3 weeks, were analyzed using a nonlinear mixed-effects modeling approach (NONMEM).

Results: The best structural model was a two-compartment model with first-order elimination. In the final model, estimated clearance (CL) and central compartment volume of distribution (Vc) were 0.207 L/day and 2.39 L for a typical female. The terminal half-life estimate was approximately 20 days for both men and women. Body weight and gender were the most significant covariates to explain interpatient variability for CL and Vc. Clearance was 26% faster in men than in women. Patients with low serum albumin and high serum alkaline phosphatase had 19 and 23% faster CL, respectively, than a typical patient. Consistent with the long elimination half life, simulations showed that similar steady-state exposures can be maintained when the weekly mg/kg dose rate is maintained, therefore allowing administration of bevacizumab to coincide with the frequency of administration of the cytotoxic agents.

Conclusion: The PK parameters were consistent with those of other IgG molecules. The results support dosing bevacizumab on a once every 2 weeks or once every 3 weeks dosing schedule on a mg/kg basis.
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October 2008

Clinical pharmacokinetics of erlotinib in patients with solid tumors and exposure-safety relationship in patients with non-small cell lung cancer.

Clin Pharmacol Ther 2006 Aug;80(2):136-45

Pharmacokinetic and Pharmacodynamic Sciences, Genentech, South San Francisco, CA 94080, USA.

Objective: Our objective was to assess the pharmacokinetics of erlotinib in a large patient population with solid tumors, identify covariates, and explore relationships between exposure and safety outcomes (rash and diarrhea) in patients with non-small cell lung cancer receiving single-agent erlotinib.

Methods: The population pharmacokinetic analysis was performed by use of NONMEM based on 4068 concentration samples from 1047 patients receiving erlotinib as a single agent or in combination with chemotherapy. By use of a 1-compartment model with first-order absorption, the influence of demographic and clinical characteristics on clearance and volume was examined. Spearman rank correlation analyses were performed to test for correlations between maximum grades of rash and diarrhea and erlotinib exposure in non-small cell lung cancer patients treated with single-agent erlotinib.

Results: On the basis of the final model developed from patients treated with erlotinib as a single agent, the oral clearance was 3.95 L/h, the oral volume of distribution was 233 L, and the absorption rate was 0.95 h(-1). The median erlotinib half-life based on this patient population was 36.2 hours. Total bilirubin, alpha1-acid glycoprotein, and smoking status were the most important factors affecting clearance. The clearance in current smokers was 24% faster than that in former smokers or those who never smoked. There was a statistically significant correlation between drug exposure and rash (P < .05). However, there was significant overlap in the range of values for patients who had no rash (grade = 0) and those who had any grade of rash. No significant correlation was found between exposure and diarrhea.

Conclusions: The long half-life of erlotinib supports the current once-daily dosing regimen at 150 mg/d. Effects of covariates on erlotinib clearance and correlations with adverse event severity were provided to aid in the detection of a treatment-emergent effect.
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August 2006

Evaluation of the absolute oral bioavailability and bioequivalence of erlotinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in a randomized, crossover study in healthy subjects.

J Clin Pharmacol 2006 Mar;46(3):282-90

CV Therapeutics, Inc, Palo Alto, California, USA.

A randomized, open-label, 2-period crossover study was conducted to evaluate the bioequivalence of 6 tablets of erlotinib 25 mg and 1 tablet of erlotinib 150 mg (arm A, n = 42) and the oral bioavailability of the 150-mg tablet versus a 25-mg intravenous infusion (arm B, n = 20) in healthy subjects. The washout period was 2 weeks between treatments. Plasma concentrations of erlotinib and its active metabolite, OSI-420, were measured after each dose. The ratios of geometric means for AUC(0-infinity) and Cmax of erlotinib following 6 tablets of erlotinib 25 mg and 1 tablet of erlotinib 150 mg were (1 and 0.95) within the predefined bioequivalence range of 0.80 to 1.25. The mean absolute oral bioavailability, using compartmental analysis, was estimated as 59% (95% confidence interval, 55%-63%). Overall, 6 tablets of erlotinib 25 mg are bioequivalent to a single 150-mg tablet. Both intravenous and oral erlotinib were generally well tolerated with an estimated bioavailability of 59% following oral administration.
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March 2006