Publications by authors named "Joseph A Ware"

44 Publications

Mechanistic physiology-based pharmacokinetic modeling to elucidate vincristine-induced peripheral neuropathy following treatment with novel kinase inhibitors.

Cancer Chemother Pharmacol 2021 Sep 2;88(3):451-464. Epub 2021 Jun 2.

Quantitative Clinical Pharmacology, AstraZeneca , South San Francisco, CA, USA.

Purpose: Limited information is available regarding the drug-drug interaction (DDI) potential of molecular targeted agents and rituximab plus cyclophosphamide, doxorubicin (hydroxydaunorubicin), vincristine (Oncovin), and prednisone (R-CHOP) therapy. The addition of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib to R-CHOP therapy results in increased toxicity versus R-CHOP alone, including higher incidence of peripheral neuropathy. Vincristine is a substrate of P-glycoprotein (P-gp, ABCB1); drugs that inhibit P-gp could potentially cause increased toxicity when co-administered with vincristine through DDI. While the combination of the BTK inhibitor acalabrutinib and R-CHOP is being explored clinically, the DDI potential between these therapies is unknown.

Methods: A human mechanistic physiology-based pharmacokinetic (PBPK) model of vincristine following intravenous dosing was developed to predict potential DDI interactions with combination therapy. In vitro absorption, distribution, metabolism, and excretion and in vivo clinical PK parameters informed PBPK model development, which was verified by comparing simulated vincristine concentrations with observed clinical data.

Results: While simulations suggested no DDI between vincristine and ibrutinib or acalabrutinib in plasma, simulated vincristine exposure in muscle tissue was increased in the presence of ibrutinib but not acalabrutinib. Extrapolation of the vincristine mechanistic PBPK model to other P-gp substrates further suggested DDI risk when ibrutinib (area under the concentration-time curve [AUC] ratio: 1.8), but not acalabrutinib (AUC ratio: 0.92), was given orally with venetoclax or digoxin.

Conclusion: Overall, these data suggest low DDI risk between acalabrutinib and P-gp substrates with negligible increase in the potential risk of vincristine-induced peripheral neuropathy when acalabrutinib is added to R-CHOP therapy.
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http://dx.doi.org/10.1007/s00280-021-04302-5DOI Listing
September 2021

Absorption, metabolism and excretion of pictilisib, a potent pan-class I phosphatidylinositol-3-Kinase (PI3K) inhibitor, in rats, dogs, and humans.

Xenobiotica 2021 Jul 24;51(7):796-810. Epub 2021 May 24.

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

The absorption, metabolism and excretion of pictilisib, a selective small molecule inhibitor of class 1 A phosphoinositide 3-kinase (PI3K), was characterized following a single oral administration of [C]pictilisib in rats, dogs and humans at the target doses of 30 mg/kg, 5 mg/kg and 60 mg, respectively.Pictilisib was rapidly absorbed with T less than 2 h across species. In systemic circulation, pictilisib represented the predominant total radioactivity greater than 86.6% in all species.Total pictilisib and related radioactivity was recovered from urine and faeces in rats, dogs, and human at 98%, 80% and 95%, respectively, with less than 2% excreted in urine and the rest excreted into faeces.In rat and dog, more than 40% of drug-related radioactivity was excreted into the bile suggesting biliary excretion was the major route of excretion. Unchanged pictilisib was a minor component in rat and dog bile. The major metabolite in bile was -glucuronide of oxidation on indazole moiety (M20, 21% of the dose) in rats and an oxidative piperazinyl ring-opened metabolite M7 (10.8% of the dose) in dogs.Oxidative glutathione (GSH) conjugates (M18, M19) were novel metabolites detected in rat bile, suggesting the potential generation of reactive intermediates from pictilisib. The structure of M18 was further confirmed by NMR to be a -hydroxylated and GSH conjugated metabolite on the moiety of the indazole ring.
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http://dx.doi.org/10.1080/00498254.2021.1923859DOI Listing
July 2021

Intrinsic and Extrinsic Pharmacokinetic Variability of Small Molecule Targeted Cancer Therapy.

Clin Transl Sci 2020 03 12;13(2):410-418. Epub 2019 Dec 12.

Department of Clinical Pharmacology, Genentech, Inc., South San Francisco, California, USA.

Pharmacokinetic (PK) variability in cancer clinical trials may be due to heterogeneous populations and identifying sources of variability is important. Use of healthy subjects in clinical pharmacology studies together with detailed knowledge of the characteristics of patients with cancer can allow for quick identification and quantification of factors affecting PK variability. PK data and sources of variability of 40 marketed molecularly targeted oncology therapeutics were compiled from regulatory approval documents covering an 18-year period (1999-2017). Variability in PK parameters was compared and contributors to variability were identified. The results show that PK variability was ~ 16% higher for peak plasma concentration (C ) and area under the concentration time curve (AUC) in patients with cancer compared with healthy subjects. Several factors were identified as major contributors to variability including hepatic/renal impairment and cytochrome P450 inhibition/induction. Lower PK variability in healthy subjects may represent an opportunity to perform rapid and robust pharmacological and PK assessments to inform subsequent studies in the development of new cancer therapies.
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http://dx.doi.org/10.1111/cts.12726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7070882PMC
March 2020

Investigation of the absolute bioavailability and human mass balance of navoximod, a novel IDO1 inhibitor.

Br J Clin Pharmacol 2019 08 14;85(8):1751-1760. Epub 2019 Jun 14.

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

Aims: Navoximod (GDC-0919, NLG-919) is a small molecule inhibitor of indoleamine-2,3-dioxygenase 1 (IDO1), developed to treat the acquired immune tolerance associated with cancer. The primary objectives of this study were to assess navoximod's absolute bioavailability (aBA), determine the mass balance and routes of elimination of [ C]-navoximod, and characterize navoximod's metabolite profile.

Methods: A phase 1, open-label, two-part study was conducted in healthy volunteers. In Part 1 (aBA), subjects (n = 16) were randomized to receive oral (200 mg tablet) or intravenous (5 mg solution) navoximod in a crossover design with a 5-day washout. In Part 2 (mass balance), subjects (n = 8) were administered [ C]-navoximod (200 mg/600 μCi) as an oral solution.

Results: The aBA of navoximod was estimated to be 55.5%, with a geometric mean (%CV) plasma clearance and volume of distribution of 62.0 L/h (21.0%) and 1120 L (28.4%), respectively. Mean recovery of total radioactivity was 87.8%, with 80.4% detected in urine and the remainder (7.4%) in faeces. Navoximod was extensively metabolized, with unchanged navoximod representing 5.45% of the dose recovered in the urine and faeces. Glucuronidation was identified as the primary route of metabolism, with the major glucuronide metabolite, M28, accounting for 57.5% of the total drug-derived exposure and 59.7% of the administered dose recovered in urine.

Conclusions: Navoximod was well tolerated, quickly absorbed and showed moderate bioavailability, with minimal recovery of the dose as unchanged parent in the urine and faeces. Metabolism was identified as the primary route of clearance and navoximod glucuronide (M28) was the most abundant metabolite in circulation with all other metabolites accounting for <10% of drug-related exposure.
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http://dx.doi.org/10.1111/bcp.13961DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6624388PMC
August 2019

ITC Commentary on Metformin Clinical Drug-Drug Interaction Study Design That Enables an Efficacy- and Safety-Based Dose Adjustment Decision.

Clin Pharmacol Ther 2018 11 15;104(5):781-784. Epub 2018 May 15.

Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.

Metformin drug-drug interaction (DDI) studies are conducted during development of drugs that inhibit organic cation transporters and/or multidrug and toxin extrusion proteins (OCTs/MATEs). Monitoring solely changes in systemic exposure, the typical DDI study endpoint appears inadequate for metformin, which is metabolically stable, has poor passive membrane permeability, and undergoes transporter-mediated tissue distribution and clearance. Evaluation of renal clearance, antihyperglycemic effects, and potentially lactate as an exploratory safety marker, can support rational metformin dose adjustment. The proposed DDI study design aims to adequately inform metformin dosing during comedication.
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http://dx.doi.org/10.1002/cpt.1082DOI Listing
November 2018

Disease-Associated Changes in Drug Transporters May Impact the Pharmacokinetics and/or Toxicity of Drugs: A White Paper From the International Transporter Consortium.

Clin Pharmacol Ther 2018 11 12;104(5):900-915. Epub 2018 Jul 12.

Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA.

Drug transporters are critically important for the absorption, distribution, metabolism, and excretion (ADME) of many drugs and endogenous compounds. Therefore, disruption of these pathways by inhibition, induction, genetic polymorphisms, or disease can have profound effects on overall physiology, drug pharmacokinetics, drug efficacy, and toxicity. This white paper provides a review of changes in transporter function associated with acute and chronic disease states, describes regulatory pathways affecting transporter expression, and identifies opportunities to advance the field.
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http://dx.doi.org/10.1002/cpt.1115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6424581PMC
November 2018

A Phase I Dose-Escalation Study of the Safety and Pharmacokinetics of Pictilisib in Combination with Erlotinib in Patients with Advanced Solid Tumors.

Oncologist 2017 12 10;22(12):1491-1499. Epub 2017 Aug 10.

Division of Pharmacology, Netherlands Cancer Institute, Amsterdam, The Netherlands.

Background: Epidermal growth factor receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K) are involved in the proliferation and survival of many cancer types. Enhanced antitumor activity may be achieved through combined inhibition of these pathways. We report results for pictilisib (GDC-0941, a class I pan-PI3K inhibitor) plus erlotinib (an EGFR tyrosine kinase inhibitor) in patients with advanced solid tumors.

Materials And Methods: A 3 + 3 dose-escalation study was carried out at a starting daily dose of 60 mg pictilisib on days 1-21 of a 28-day cycle and 150 mg erlotinib from day 2 of cycle 1. The primary objectives of the study were to assess safety and tolerability, identify dose-limiting toxicities (DLTs), estimate the maximum tolerated dose, and identify the recommended phase II dose (RP2D). Evaluation of a dose-expansion cohort at the RP2D was performed.

Results: Fifty-seven patients were treated in the study. All patients experienced at least one adverse event (AE). Grade ≥3 AEs, serious AEs, and deaths were reported in 38 (66.7%), 19 (33.3%), and 4 (7.0%) patients, respectively. DLTs occurred in nine patients across eight cohorts and the RP2D was determined to be 340 mg pictilisib on a "5 days on, 2 days off" schedule plus 100 mg erlotinib. Two patients (3.5%) experienced partial response and 19 (33.3%) had stable disease.

Conclusion: Combining pictilisib with erlotinib in patients with advanced solid tumors is feasible; however, antitumor activity is limited. Additional studies may identify patients likely to benefit from combined inhibition of EGFR and PI3K pathways.

Implications For Practice: Combining drugs targeting different signaling pathways in cancer growth and survival could overcome drug resistance and improve antitumor activity. In this first-in-human study for the combination, addition of the PI3K inhibitor pictilisib to the EGFR tyrosine kinase inhibitor erlotinib resulted in toxicity that led to dose and schedule modifications to identify a tolerable recommended phase II dose of 340 mg pictilisib on a "5 days on, 2 days off" schedule plus 100 mg erlotinib daily. The limited antitumor activity observed, however, suggests that additional studies are needed to identify patients most likely to benefit from combined EGFR and PI3K inhibition.
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http://dx.doi.org/10.1634/theoncologist.2017-0090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5728021PMC
December 2017

Combining "Bottom-up" and "Top-down" Approaches to Assess the Impact of Food and Gastric pH on Pictilisib (GDC-0941) Pharmacokinetics.

CPT Pharmacometrics Syst Pharmacol 2017 11 17;6(11):747-755. Epub 2017 Oct 17.

Department of Clinical Pharmacology, Genentech Inc, South San Francisco, California, USA.

Pictilisib, a weakly basic compound, is an orally administered, potent, and selective pan-inhibitor of phosphatidylinositol 3-kinases for oncology indications. To investigate the significance of high-fat food and gastric pH on pictilisib pharmacokinetics (PK) and enable label recommendations, a dedicated clinical study was conducted in healthy volunteers, whereby both top-down (population PK, PopPK) and bottom-up (physiologically based PK, PBPK) approaches were applied to enhance confidence of recommendation and facilitate the clinical development through scenario simulations. The PopPK model identified food (for absorption rate constant (K )) and proton pump inhibitors (PPI, for relative bioavailability (F ) and K ) as significant covariates. Food and PPI also impacted the variability of F . The PBPK model accounted for the supersaturation tendency of pictilisib, and gastric emptying physiology successfully predicted the food and PPI effect on pictilisib absorption. Our research highlights the importance of applying both quantitative approaches to address critical drug development questions.
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http://dx.doi.org/10.1002/psp4.12228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5702897PMC
November 2017

Phase I Dose-Escalation Study of Taselisib, an Oral PI3K Inhibitor, in Patients with Advanced Solid Tumors.

Cancer Discov 2017 07 22;7(7):704-715. Epub 2017 Mar 22.

Memorial Sloan Kettering Cancer Center, New York, New York.

Taselisib is a potent and selective tumor growth inhibitor through PI3K pathway suppression. Thirty-four patients with locally advanced or metastatic solid tumors were treated (phase I study, modified 3+3 dose escalation; 5 cohorts; 3-16 mg taselisib once-daily capsule). Taselisib pharmacokinetics were dose-proportional; mean half-life was 40 hours. Frequent dose-dependent, treatment-related adverse events included diarrhea, hyperglycemia, decreased appetite, nausea, rash, stomatitis, and vomiting. At 12 and 16 mg dose levels, dose-limiting toxicities (DLT) were observed, with an accumulation of higher-grade adverse events after the cycle 1 DLT assessment window. Pharmacodynamic findings showed pathway inhibition at ≥3 mg in patient tumor samples, consistent with preclinical -mutant tumor xenograft models. Confirmed response rate was 36% for -mutant tumor patients with measurable disease [5/14: 4 breast cancer (3 patients at 12 mg); 1 non-small cell lung cancer], where responses started at 3 mg, and 0% in patients with tumors without known hotspot mutations (0/15). Preliminary data consistent with preclinical data indicate increased antitumor activity of taselisib in patients with -mutant tumors (in comparison with patients with tumors without known activating hotspot mutations) starting at the lowest dose tested of 3 mg, thereby supporting higher potency for taselisib against -mutant tumors. .
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http://dx.doi.org/10.1158/2159-8290.CD-16-1080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501742PMC
July 2017

Pharmacogenomics in the age of personalized medicine.

Drug Discov Today Technol 2016 Sep - Dec;21-22:11-16

Department of Clinical Pharmacology, Genentech, 1 DNA Way, South San Francisco, CA 94080, United States.

The aim of personalized medicine is to offer the right treatment to the right person at the right dose, thus maximizing efficacy and minimizing toxicity for each individual patient. Pharmacogenomic approaches attempt to refine the aim of personalized medicine by utilizing an individual's germline and somatic DNA signatures to guide treatment. In this review, we highlight the current use of pharmacogenomic based biomarker information in drug labeling. We also present several case studies on the implementation of pharmacogenomic strategies in drug discovery and development. Lastly, we comment on current challenges to implementing pharmacogenomic based testing in the clinic.
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http://dx.doi.org/10.1016/j.ddtec.2016.11.003DOI Listing
February 2017

A multicenter, single-arm, open-label, phase 2 study of apitolisib (GDC-0980) for the treatment of recurrent or persistent endometrial carcinoma (MAGGIE study).

Cancer 2016 Nov 7;122(22):3519-3528. Epub 2016 Sep 7.

Gynecologic Medical Oncology Service, Memorial Sloan Kettering Cancer Center, New York, New York.

Background: The current single-arm, open-label trial was designed to evaluate the activity of apitolisib (GDC-0980), a dual phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor, in patients with advanced endometrial cancer (EC).

Methods: Patients with recurrent or persistent EC who were treated with 1 to 2 prior lines of chemotherapy but no prior PI3K/mTOR inhibitor received oral apitolisib at a dose of 40 mg daily during 28-day cycles until disease progression or intolerable toxicity occurred. Patients with type I/II diabetes who required insulin were excluded. The primary endpoints were progression-free survival (PFS) at 6 months and objective response rate.

Results: A total of 56 women were enrolled, including 13 (23%) with well-controlled diabetes. Reasons for discontinuation were disease progression (24 patients; 43%), adverse events (13 patients; 23%), and withdrawal by subject (12 patients; 21%). Grade 3/4 apitolisib-related adverse events were hyperglycemia (46%), rash (30%), colitis (5%), and pneumonitis (4%) (toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). The PFS rate at 6 months was 20% (Kaplan-Meier estimate; 95% confidence interval [95% CI], 7%-33%). The objective response rate was 6% (confirmed). The median PFS was 3.5 months (95% CI, 2.7-3.7 months) and the median overall survival was 15.7 months (95% CI, 9.2-17.0 months). Nineteen patients discontinued the study before the first tumor assessment. Dose reductions were required for 4 diabetic (31%) and 18 nondiabetic (42%) patients. Comprehensive molecular profiling of 46 evaluable archival tumor samples demonstrated that 57% of patients had at least 1 alteration in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), phosphatase and tensin homolog (PTEN), or AKT1. All 3 patients with a confirmed response had at least 1 alteration in a PI3K pathway gene.

Conclusions: The antitumor activity noted with the use of a dose of 40 mg of apitolisib daily was limited by tolerability, especially in diabetic patients. Patients with PI3K pathway mutations may have derived enhanced benefit from apitolisib. Cancer 2016;122:3519-28. © 2016 American Cancer Society.
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http://dx.doi.org/10.1002/cncr.30286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5600677PMC
November 2016

Simultaneous determination of itraconazole, hydroxy itraconazole, keto itraconazole and N-desalkyl itraconazole concentration in human plasma using liquid chromatography with tandem mass spectrometry.

J Chromatogr B Analyt Technol Biomed Life Sci 2016 May 26;1020:111-9. Epub 2016 Mar 26.

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

A high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) assay was developed and validated for simultaneous determination of itraconazole (ITZ), hydroxy-itraconazole (OH-ITZ), keto-itraconazole (keto-ITZ) and N-desalkyl itraconazole (ND-ITZ) concentration in human plasma. One hundred and fifty microliters of human plasma were extracted using a solid-supported liquid extraction (SLE) method and the final extracts were analyzed using reverse-phase chromatography and positive electrospray ionization mass spectrometry. The standard curve range is 5-2500 ng/mL for ITZ and OH-ITZ and 0.4-200 ng/mL for keto-ITZ and ND-ITZ. The curve was fitted to a 1/x(2) weighted linear regression model for all analytes. The precision and accuracy of the LC-MS/MS assay based on the five analytical quality control (QC) levels were well within the acceptance criteria from both FDA and EMA guidance for bioanalytical method validation. Average extraction recovery was 97.4% for ITZ, 112.9% for OH-ITZ, 103.4% for keto-ITZ, and 102.3% for ND-ITZ across their respective curve range. Matrix factor was close to 1.0 at both high and low QC levels of all 4 analytes, which indicates minimal ion suppression or enhancement in our validated assay. Itraconazole and all three metabolites are stable in human plasma for 145 days stored at -70 °C freezers. The validated assay was successfully applied to a clinical study, which has a drug-drug interaction (DDI) arm using ITZ as a cytochrome P450, family 3, subfamily A (CYP3A) inhibitor.
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http://dx.doi.org/10.1016/j.jchromb.2016.03.039DOI Listing
May 2016

Randomized Open-Label Phase II Trial of Apitolisib (GDC-0980), a Novel Inhibitor of the PI3K/Mammalian Target of Rapamycin Pathway, Versus Everolimus in Patients With Metastatic Renal Cell Carcinoma.

J Clin Oncol 2016 05 7;34(14):1660-8. Epub 2016 Mar 7.

Thomas Powles, Queen Mary University of London, London; Christy Ralph, University of Leeds, Leeds; Janet E. Brown, University of Sheffield, Sheffield; Robert E. Hawkins, University of Manchester, Manchester, United Kingdom; Mark R. Lackner, Wei Lin, Bridget O'Keeffe, Yulei Wang, Shan Lu, Jill M. Spoerke, Ling Yuh Huw, Michelle Byrtek, Rui Zhu, and Joseph A. Ware, Genentech, South San Francisco, CA; Robert J. Motzer, Memorial Sloan Kettering Cancer Center, New York, NY; Brian I. Rini, Cleveland Clinic Taussig Cancer Institute, Cleveland, OH; Bernard Escudier, Institut Gustave Roussy, Villejuif; Alain Ravaud, Hospital Saint Andre, Bordeaux; Stéphane Oudard, University Paris Descartes, Paris, France; Daniel Castellano, University Hospital 12 de Octubre, Madrid, Spain; and Michael D. Staehler, University Hospital Munich-Grosshadern, Marchioninistrasse, Germany.

Purpose: To the best of our knowledge, this study is the first to compare dual inhibition of PI3K/mammalian target of rapamycin (mTOR) by apitolisib (GDC-0980) against single inhibition of mTORC1 by everolimus in metastatic renal cell carcinoma (mRCC).

Patients And Methods: Patients with clear-cell mRCC who progressed on or after vascular endothelial growth factor-targeted therapy were randomly assigned to apitolisib 40 mg once per day or to everolimus 10 mg once per day. End points included progression-free survival, safety, overall survival, and objective response rate. Biomarker assessments were conducted.

Results: Eighty-five patients were randomly assigned. After 67 events, stratified analysis revealed that median progression-free survival was significantly shorter for apitolisib than for everolimus (3.7 v 6.1 months; hazard ratio, 2.12 [95% CI, 1.23 to 3.63; P < .01]); apitolisib was not favored in any stratification subgroup. Median overall survival was not significantly different but trended in favor of everolimus (16.5 v 22.8 months; hazard ratio, 1.77 [95% CI, 0.97 to 3.24; P = .06]). The objective response rate was 7.1% for apitolisib and 11.6% for everolimus. Patients administered apitolisib with a greater incidence of grade 3 to 4 adverse events were more likely to discontinue treatment (31% v 12% for everolimus). No drug-related deaths were observed. Apitolisib in comparison with everolimus was associated with substantially more high-grade hyperglycemia (40% v 9%) and rash (24% v 2%). Apitolisib pharmacokinetics suggested a relationship between exposure, and rash and hyperglycemia. Retrospective biomarker analyses revealed a relationship between VHL mutation status and outcome with everolimus but not with apitolisib. High hypoxia-inducible factor 1α protein expression was associated with better outcome in both arms.

Conclusion: This study demonstrated that dual PI3K/mTOR inhibition by apitolisib was less effective than was everolimus in mRCC, likely because full blockade of PI3K/mTOR signaling resulted in multiple on-target adverse events. VHL mutation and hypoxia-inducible factor 1α expression may be predictive of an mTOR inhibitor benefit, although prospective validation is required.
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http://dx.doi.org/10.1200/JCO.2015.64.8808DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569691PMC
May 2016

Phase I Study of Apitolisib (GDC-0980), Dual Phosphatidylinositol-3-Kinase and Mammalian Target of Rapamycin Kinase Inhibitor, in Patients with Advanced Solid Tumors.

Clin Cancer Res 2016 06 19;22(12):2874-84. Epub 2016 Jan 19.

The Institute of Cancer Research, The Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom.

Purpose: This first-in-human phase I trial assessed the safety, tolerability, and preliminary antitumor activity of apitolisib (GDC-0980), a dual inhibitor of class I PI3K, and mTOR kinases.

Experimental Design: Once-daily oral apitolisib was administered to patients with solid tumors for days 1 to 21 or 1 to 28 of 28-day cycles. Pharmacokinetic and pharmacodynamic parameters were assessed.

Results: Overall, 120 patients were treated at doses between 2 and 70 mg. The commonest ≥G3 toxicities related to apitolisib at the recommended phase 2 dose (RP2D) at 40 mg once daily included hyperglycemia (18%), rash (14%), liver dysfunction (12%), diarrhea (10%), pneumonitis (8%), mucosal inflammation (6%), and fatigue (4%). Dose-limiting toxicities (1 patient each) were G4 fasting hyperglycemia at 40 mg (21/28 schedule) and G3 maculopapular rash and G3 fasting hyperglycemia at 70 mg (21/28 schedule). The pharmacokinetic profile was dose-proportional. Phosphorylated serine-473 AKT levels were suppressed by ≥90% in platelet-rich plasma within 4 hours at the MTD (50 mg). Pharmacodynamic decreases in fluorodeoxyglucose positron emission tomography uptake of >25% occurred in 66% (21/32) of patients dosed at 40 mg once daily. Evidence of single-agent activity included 10 RECIST partial responses (PR; confirmed for peritoneal mesothelioma, PIK3CA mutant head-and-neck cancer, and three pleural mesotheliomas).

Conclusions: Apitolisib exhibited dose-proportional pharmacokinetics with target modulation at doses ≥16 mg. The RP2D was 40 mg once-daily 28/28 schedule; severe on-target toxicities were apparent at ≥40 mg, particularly pneumonitis. Apitolisib was reasonably tolerated at 30 mg, the selected dose for pleural mesothelioma patients given limited respiratory reserve. Modest but durable antitumor activity was demonstrated. Clin Cancer Res; 22(12); 2874-84. ©2016 AACR.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-2225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4876928PMC
June 2016

Breast cancer resistance protein (ABCG2) in clinical pharmacokinetics and drug interactions: practical recommendations for clinical victim and perpetrator drug-drug interaction study design.

Drug Metab Dispos 2015 Apr 13;43(4):490-509. Epub 2015 Jan 13.

Drug Metabolism and Pharmacokinetics, QPS LLC, Research Triangle Park, North Carolina (C.A.L.); Drug Metabolism and Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut (M.A.O., M.E.T.); Centre for Applied Pharmacokinetic Research, Manchester Pharmacy School, The University of Manchester, Manchester, United Kingdom (A.G.); Pharmacokinetics and Drug Metabolism (B.F.) and Clinical Pharmacology, Global Innovative Pharma Business (J.A.C.), Pfizer Inc., Groton, Connecticut; School of Pharmacy, University of Washington, Seattle, Washington (I.R.-M., T.K.R.); Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, Research Triangle Park, North Carolina (M.J.Z.-G., J.W.P.) and King of Prussia, Pennsylvania (H.E.); College of Pharmacy, Washington State University, Spokane, Washington (M.F.P.); and Clinical Pharmacology, Genentech, South San Francisco, California (J.A.W.)

Breast cancer resistance protein (BCRP; ABCG2) limits intestinal absorption of low-permeability substrate drugs and mediates biliary excretion of drugs and metabolites. Based on clinical evidence of BCRP-mediated drug-drug interactions (DDIs) and the c.421C>A functional polymorphism affecting drug efficacy and safety, both the US Food and Drug Administration and European Medicines Agency recommend preclinical evaluation and, when appropriate, clinical assessment of BCRP-mediated DDIs. Although many BCRP substrates and inhibitors have been identified in vitro, clinical translation has been confounded by overlap with other transporters and metabolic enzymes. Regulatory recommendations for BCRP-mediated clinical DDI studies are challenging, as consensus is lacking on the choice of the most robust and specific human BCRP substrates and inhibitors and optimal study design. This review proposes a path forward based on a comprehensive analysis of available data. Oral sulfasalazine (1000 mg, immediate-release tablet) is the best available clinical substrate for intestinal BCRP, oral rosuvastatin (20 mg) for both intestinal and hepatic BCRP, and intravenous rosuvastatin (4 mg) for hepatic BCRP. Oral curcumin (2000 mg) and lapatinib (250 mg) are the best available clinical BCRP inhibitors. To interrogate the worst-case clinical BCRP DDI scenario, study subjects harboring the BCRP c.421C/C reference genotype are recommended. In addition, if sulfasalazine is selected as the substrate, subjects having the rapid acetylator phenotype are recommended. In the case of rosuvastatin, subjects with the organic anion-transporting polypeptide 1B1 c.521T/T genotype are recommended, together with monitoring of rosuvastatin's cholesterol-lowering effect at baseline and DDI phase. A proof-of-concept clinical study is being planned by a collaborative consortium to evaluate the proposed BCRP DDI study design.
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http://dx.doi.org/10.1124/dmd.114.062174DOI Listing
April 2015

First-in-human phase I study of pictilisib (GDC-0941), a potent pan-class I phosphatidylinositol-3-kinase (PI3K) inhibitor, in patients with advanced solid tumors.

Clin Cancer Res 2015 Jan 4;21(1):77-86. Epub 2014 Nov 4.

The Royal Marsden National Health Service (NHS) Foundation Trust, Sutton, Surrey, United Kingdom.

Purpose: This first-in-human dose-escalation trial evaluated the safety, tolerability, maximal-tolerated dose (MTD), dose-limiting toxicities (DLT), pharmacokinetics, pharmacodynamics, and preliminary clinical activity of pictilisib (GDC-0941), an oral, potent, and selective inhibitor of the class I phosphatidylinositol-3-kinases (PI3K).

Patients And Methods: Sixty patients with solid tumors received pictilisib at 14 dose levels from 15 to 450 mg once-daily, initially on days 1 to 21 every 28 days and later, using continuous dosing for selected dose levels. Pharmacodynamic studies incorporated (18)F-FDG-PET, and assessment of phosphorylated AKT and S6 ribosomal protein in platelet-rich plasma (PRP) and tumor tissue.

Results: Pictilisib was well tolerated. The most common toxicities were grade 1-2 nausea, rash, and fatigue, whereas the DLT was grade 3 maculopapular rash (450 mg, 2 of 3 patients; 330 mg, 1 of 7 patients). The pharmacokinetic profile was dose-proportional and supported once-daily dosing. Levels of phosphorylated serine-473 AKT were suppressed >90% in PRP at 3 hours after dose at the MTD and in tumor at pictilisib doses associated with AUC >20 h·μmol/L. Significant increase in plasma insulin and glucose levels, and >25% decrease in (18)F-FDG uptake by PET in 7 of 32 evaluable patients confirmed target modulation. A patient with V600E BRAF-mutant melanoma and another with platinum-refractory epithelial ovarian cancer exhibiting PTEN loss and PIK3CA amplification demonstrated partial response by RECIST and GCIG-CA125 criteria, respectively.

Conclusion: Pictilisib was safely administered with a dose-proportional pharmacokinetic profile, on-target pharmacodynamic activity at dose levels ≥100 mg and signs of antitumor activity. The recommended phase II dose was continuous dosing at 330 mg once-daily.
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http://dx.doi.org/10.1158/1078-0432.CCR-14-0947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4287394PMC
January 2015

Breast cancer resistance protein substrate and inhibition evaluation: why, when, and how?

Drug Metab Dispos 2014 Dec;42(12):1979-80

Clinical Pharmacology, Genentech, South San Francisco, California (J.A.W.); University of Western Ontario, London, Ontario, Canada (B.L.U.); RIKEN Innovation Center, Yokohama, Kanagawa, Japan (Y.S.); and Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, Research Triangle Park, North Carolina (M.J.Z.-G.).

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http://dx.doi.org/10.1124/dmd.114.060970DOI Listing
December 2014

The use of betaine HCl to enhance dasatinib absorption in healthy volunteers with rabeprazole-induced hypochlorhydria.

AAPS J 2014 Nov 2;16(6):1358-65. Epub 2014 Oct 2.

Department of Bioengineering and Therapeutic Sciences, University of California, 533 Parnassus Avenue, Room U-68, San Francisco, California, 94143-0912, USA.

Many orally administered, small-molecule, targeted anticancer drugs, such as dasatinib, exhibit pH-dependent solubility and reduced drug exposure when given with acid-reducing agents. We previously demonstrated that betaine hydrochloride (BHCl) can transiently re-acidify gastric pH in healthy volunteers with drug-induced hypochlorhydria. In this randomized, single-dose, three-way crossover study, healthy volunteers received dasatinib (100 mg) alone, after pretreatment with rabeprazole, and with 1500 mg BHCl after rabeprazole pretreatment, to determine if BHCl can enhance dasatinib absorption in hypochlorhydric conditions. Rabeprazole (20 mg b.i.d.) significantly reduced dasatinib Cmax and AUC0-∞ by 92 and 78%, respectively. However, coadministration of BHCl significantly increased dasatinib Cmax and AUC0-∞ by 15- and 6.7-fold, restoring them to 105 and 121%, respectively, of the control (dasatinib alone). Therefore, BHCl reversed the impact of hypochlorhydria on dasatinib drug exposure and may be an effective strategy to mitigate potential drug-drug interactions for drugs that exhibit pH-dependent solubility and are administered orally under hypochlorhydric conditions.
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http://dx.doi.org/10.1208/s12248-014-9673-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4389759PMC
November 2014

Physical chemical drug-drug interactions from drug discovery to registration: new opportunities for the pharmaceutical scientist to impact drug development.

Mol Pharm 2013 Nov;10(11):3967-9

Small Molecule Clinical Pharmacology and §Small Molecule Pharmaceutical Sciences, Genentech Research and Early Development , 1 DNA Way, South San Francisco, California 94080, United States.

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http://dx.doi.org/10.1021/mp4005639DOI Listing
November 2013

Impact of food and the proton pump inhibitor rabeprazole on the pharmacokinetics of GDC-0941 in healthy volunteers: bench to bedside investigation of pH-dependent solubility.

Mol Pharm 2013 Nov 24;10(11):4074-81. Epub 2013 Oct 24.

Small Molecule Clinical Pharmacology, ‡Small Molecule Pharmaceutical Sciences, §Drug Metabolism and Pharmacokinetics, ∥Clinical Project Management, and ⊥Early Clinical Development, Genentech Research and Early Development , 1 DNA Way, South San Francisco, California 94080, United States.

GDC-0941 is an orally administered potent, selective pan-inhibitor of phosphatidylinositol 3-kinases (PI3Ks) with good preclinical antitumor activity in xenograft models and favorable pharmacokinetics and tolerability in phase 1 trials, and it is currently being investigated in phase II clinical trials as an anti-cancer agent. In vitro solubility and dissolution studies suggested that GDC-0941, a weak base, displays significant pH-dependent solubility. Moreover, preclinical studies conducted in famotidine-induced hypochlorhydric dog suggested that the pharmacokinetics of GDC-0941 may be sensitive to pharmacologically induced hypochlorhydria. To investigate the clinical significance of food and pH-dependent solubility on GDC-0941 pharmacokinetics a four-period, two-sequence, open-label, randomized, crossover study was conducted in healthy volunteers. During the fasting state, GDC-0941 was rapidly absorbed with a median Tmax of 2 h. The presence of a high-fat meal delayed the absorption of GDC-0941, with a median Tmax of 4 h and a modest increase in AUC relative to the fasted state, with an estimated geometric mean ratio (GMR, 90% CI) of fed/fasted of 1.28 (1.08, 1.51) for AUC0-∞ and 0.87 (0.70, 1.06) for Cmax. The effect of rabeprazole (model PPI) coadministration on the pharmacokinetics of GDC-0941 was evaluated in the fasted and fed state. When comparing the effect of rabeprazole + GDC-0941 (fasted) to baseline GDC-0941 absorption in a fasted state, GDC-0941 median Tmax was unchanged, however, both Cmax and AUC0-∞ decreased significantly after pretreatment with rabeprazole, with an estimated GMR (90% CI) of 0.31 (0.21, 0.46) and 0.46 (0.35, 0.61), respectively for both parameters. When rabeprazole was administered in the presence of the high-fat meal, the impact of food did not fully reverse the pH effect; the overall effect of rabeprazole on AUC0-∞ was somewhat attenuated by the high-fat meal (estimate GMR of 0.57, with 90% CI, 0.50, 0.65) but unchanged for the Cmax (estimate of 0.43, with 90% CI, 0.37, 0.50). The results of the current investigations emphasize the complex nature of physicochemical interactions and the importance of gastric acid for the dissolution and solubilization processes of GDC-0941. Given these findings, dosing of GDC-0941 in clinical trials was not constrained relative to fasted/fed states, but the concomitant use of ARAs was restricted. Mitigation strategies to limit the influence of pH on exposure of molecularly targeted agents such as GDC-0941 with pH-dependent solubility are discussed.
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http://dx.doi.org/10.1021/mp4005595DOI Listing
November 2013

Prevalence of acid-reducing agents (ARA) in cancer populations and ARA drug-drug interaction potential for molecular targeted agents in clinical development.

Mol Pharm 2013 Nov 24;10(11):4055-62. Epub 2013 Oct 24.

Clinical Pharmacology, Genentech Research and Early Development , 1 DNA Way, South San Francisco, California 94080, United States.

Acid-reducing agents (ARAs) are the most commonly prescribed medications in North America and Western Europe. There are currently no data describing the prevalence of their use among cancer patients. However, this is a paramount question due to the potential for significant drug-drug interactions (DDIs) between ARAs, most commonly proton pump inhibitors (PPIs), and orally administered cancer therapeutics that display pH-dependent solubility, which may lead to decreased drug absorption and decreased therapeutic benefit. Of recently approved orally administered cancer therapeutics, >50% are characterized as having pH-dependent solubility, but there are currently no data describing the potential for this ARA-DDI liability among targeted agents currently in clinical development. The objectives of this study were to (1) determine the prevalence of ARA use among different cancer populations and (2) investigate the prevalence of orally administered cancer therapeutics currently in development that may be liable for an ARA-DDI. To address the question of ARA use among cancer patients, a retrospective cross-sectional analysis was performed using two large healthcare databases: Thomson Reuters MarketScan (N = 1,776,443) and the U.S. Department of Veterans Affairs (VA, N = 1,171,833). Among all cancer patients, the total prevalence proportion of ARA use (no. of cancer patients receiving an ARA/total no. of cancer patients) was 20% and 33% for the MarketScan and VA databases, respectively. PPIs were the most commonly prescribed agent, comprising 79% and 65% of all cancer patients receiving a prescription for an ARA (no. of cancer patients receiving a PPI /no. of cancer patients receiving an ARA) for the MarketScan and VA databases, respectively. To estimate the ARA-DDI liability of orally administered molecular targeted cancer therapeutics currently in development, two publicly available databases, (1) Kinase SARfari and (2) canSAR, were examined. For those orally administered clinical candidates that had available structures, the pKa's and corresponding relative solubilities were calculated for a normal fasting pH of 1.2 and an "ARA-hypochlorhydric" pH of 4. Taking calculated pKa's and relative solubilities into consideration, clinical candidates were classified based on their risk for an ARA-DDI. More than one-quarter (28%) of the molecules investigated are at high risk for an ARA-DDI, and of those high risk molecules, nearly three-quarters (73%) are being clinically evaluated for at least one of five cancer types with the highest prevalence of ARA use (gastrointestinal, pancreatic, lung, glioblastoma multiforme, gastrointestinal stromal tumor (GIST)). These data strongly suggest that with the clinical development of ARA-DDI-susceptible cancer therapeutics will come continued challenges for drug-development scientists, oncologists, and regulatory agencies in ensuring that patients achieve safe and efficacious exposures of their cancer therapeutics and thus optimal patient outcomes.
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http://dx.doi.org/10.1021/mp400403sDOI Listing
November 2013

Gastric reacidification with betaine HCl in healthy volunteers with rabeprazole-induced hypochlorhydria.

Mol Pharm 2013 Nov 10;10(11):4032-7. Epub 2013 Sep 10.

Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco , 533 Parnassus Avenue, San Francisco, California 94143-0912, United States.

Previous studies have demonstrated that increased gastric pH from the use of acid-reducing agents, such as proton-pump inhibitors or H2-receptor antagonists, can significantly impact the absorption of weakly basic drugs that exhibit pH-dependent solubility. Clinically practical strategies to mitigate this interaction have not been developed. This pilot study evaluated the extent and time course of gastric reacidification after a solid oral dosage form of anhydrous betaine HCl in healthy volunteers with pharmacologically induced hypochlorhydria. Six healthy volunteers with baseline normochlorhydria (fasting gastric pH < 4) were enrolled in this single period study. Hypochlorhydria was induced via 20 mg oral rabeprazole twice daily for four days. On the fifth day, an additional 20 mg dose of oral rabeprazole was given and gastric pH was monitored continuously using the Heidelberg pH capsule. After gastric pH > 4 was confirmed for 15 min, 1500 mg of betaine HCl was given orally with 90 mL of water and gastric pH was continuously monitored for 2 h. Betaine HCl significantly lowered gastric pH by 4.5 (± 0.5) units from 5.2 (± 0.5) to 0.6 (± 0.2) (P < 0.001) during the 30 min interval after administration. The onset of effect of betaine HCl was rapid, with a mean time to pH < 3 of 6.3 (± 4.3) min. The reacidification period was temporary with a gastric pH < 3 and < 4 lasting 73 (± 33) and 77 (± 30) min, respectively. Betaine HCl was well tolerated by all subjects. In healthy volunteers with pharmacologically induced hypochlorhydria, betaine HCl was effective at temporarily lowering gastric pH. The rapid onset and relatively short duration of gastric pH reduction gives betaine HCl the potential to aid the absorption of orally administered weakly basic drugs that exhibit pH-dependent solubility when administered under hypochlorhydric conditions.
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http://dx.doi.org/10.1021/mp4003738DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946491PMC
November 2013

Pharmacokinetics and absorption of the anticancer agents dasatinib and GDC-0941 under various gastric conditions in dogs--reversing the effect of elevated gastric pH with betaine HCl.

Mol Pharm 2013 Nov 11;10(11):4024-31. Epub 2013 Sep 11.

Department of Drug Metabolism and Pharmacokinetics, ‡Department of Small Molecule Pharmaceutical Sciences, and §Department of Small Molecule Clinical Pharmacology, Genentech, Inc. , South San Francisco, California 94080, United States.

Changes in gastric pH can impact the dissolution and absorption of compounds presenting pH-dependent solubility. We assessed, in dogs, the effects of gastric pH-modifying agents on the oral absorption of two weakly basic anticancer drugs, dasatinib and GDC-0941. We also tested whether drug-induced hypochlorhydria could be temporarily mitigated using betaine HCl. Pretreatments with pentagastrin, famotidine, betaine HCl, or combinations of famotidine and betaine HCl were administered orally to dogs prior to drug dosing. The gastric pH was measured under each condition for up to 7 h, and the exposure of the compounds tested was calculated. The average gastric pH in fasted dogs ranged from 1.45 to 3.03. Pentagastrin or betaine HCl treatments lowered the pH and reduced its variability between dogs compared to control animals. In contrast, famotidine treatment maintained gastric pH at values close to 7 for up to 5 h, while betaine HCl transiently reduced the pH to approximately 2 in the famotidine-treated dogs. Famotidine pretreatment lowered GDC-0941 exposure by 5-fold, and decreased dasatinib measurable concentrations 30-fold, compared to the pentagastrin-treated dogs. Betaine HCl restored GDC-0941 AUC in famotidine-treated dogs to levels achieved in control animals, and increased dasatinib AUC to 1.5-fold that measured in control dogs. The results confirmed the negative impact of acid-reducing agents on the absorption of weakly basic drugs. They also suggested that betaine HCl coadministration may be a viable strategy in humans treated with acid-reducing agents in order to temporarily reduce gastric pH and restore drug exposure.
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http://dx.doi.org/10.1021/mp400356mDOI Listing
November 2013

Evaluation of metabolism and disposition of GDC-0152 in rats using 14C labeling strategy at two different positions: a novel formation of hippuric acid from 4-phenyl-5-amino-1,2,3-thiadiazole.

Drug Metab Dispos 2013 Feb 4;41(2):508-17. Epub 2012 Dec 4.

Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, CA 94080, USA.

The compound (S)-1-[(S)-2-cyclohexyl-2-([S]-2-[methylamino]propanamido)acetyl]-N-(4-phenyl-1,2,3-thiadiazol-5-yl)pyrrolidine-2-carboxamide (GDC-0152) is a peptidomimetic small molecule antagonist of inhibitor of apoptosis (IAP) proteins with antitumor activity. The mass balance, pharmacokinetics, tissue distribution and metabolism of GDC-0152 was investigated in rats following intravenous administration of 15 mg/kg of [(14)C]GDC-0152, labeled either at the terminal phenyl ring (A) or at the carbonyl of the 2-amino-2-cyclohexylacetyl moiety (B). In rats, 92.2%-95.1% of the radiolabeled GDC-0152 dose was recovered. Approximately 62.3% and 25.1% of A was excreted in urine and feces, respectively. By contrast, B was excreted almost equally in urine (27.2%), feces (32.2%), and expired air (27.5%). GDC-0152 underwent extensive metabolism, with less than 9% of the dose recovered as parent in excreta. Similarly, in plasma, GDC-0152 represented 16.7% and 7.5% of the area under the curve of the total radioactivity for A and B, respectively. The terminal half-life (t(1/2)) for total radioactivity was longer for B (21.2 hours) than for A (4.59 hours). GDC-0152 was highly metabolized via oxidation and amide hydrolysis, followed by subsequent sulfation and glucuronidation. The most abundant circulating metabolites were the amide hydrolyzed products, M26, M28, M30, M31, and M34, which ranged from 3.5% to 9.0% of total radioactivity. In quantitative whole-body autoradiography studies, the residence of radioactivity in tissues was longer for B than for A, which is consistent with the t(1/2) of the total radioactivity in circulation. A novel 4-phenyl-5-amino-1,2,3-thiadiazole (M28) oxidative cleavage resulted in the formation of hippuric acid (M24). This biotransformation was also observed in rat hepatocyte incubations with para-substituted M28 analogs. In addition, the formation of M24 was inhibited by 1-aminobenzotriazole, which points to the involvement of P450 enzymes.
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http://dx.doi.org/10.1124/dmd.112.047019DOI Listing
February 2013

Dogs are more sensitive to antagonists of inhibitor of apoptosis proteins than rats and humans: a translational toxicokinetic/toxicodynamic analysis.

Toxicol Sci 2012 Nov 28;130(1):205-13. Epub 2012 Jul 28.

Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, California, USA.

Inhibitor of apoptosis (IAP) proteins suppress apoptosis and are overexpressed in a variety of cancers. GDC-0152 is a potent and selective IAP antagonist being developed as an anticancer agent. In preclinical safety studies, dogs were particularly sensitive to GDC-0152 showing adverse signs of a tumor necrosis factor alpha (TNF-α) driven systemic inflammatory response, related to cellular IAP degradation and activation of NFκB signaling, at lower exposures compared with rat. In addition, downstream increases in systemic levels of cytokines and chemokines, such as monocyte chemotactic protein-1 (MCP-1), were observed. A semimechanistic population toxicokinetic/toxicodynamic (TK/TD) model incorporating transit compartments was used to fit MCP-1 plasma concentrations from rats or dogs given iv GDC-0152 doses. Estimated TD parameters inferred that lower GDC-0152 plasma concentrations triggered more severe increases in plasma MCP-1 in dogs compared with rats. Human simulations performed using dog TD parameters and human pharmacokinetics predicted 300-2400% increases of MCP-1 in humans at iv doses from 0.76 to 1.48mg/kg. Similar simulations using rat TD parameters suggest little or no change. Patients given iv doses of GDC-0152 up to 1.48mg/kg iv showed no substantial increases in systemic MCP-1 or signs of a severe TNF-α driven systemic inflammatory response. Emerging clinical data reported for other IAP antagonists are consistent with our observations. Taken together, the data suggest dogs are more sensitive to IAP antagonists compared with humans and rats. This study illustrates how TK/TD analysis can be utilized to quantitatively translate and context an identified preclinical safety risk in dogs to humans.
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http://dx.doi.org/10.1093/toxsci/kfs235DOI Listing
November 2012

Bridging the gap between preclinical and clinical studies using pharmacokinetic-pharmacodynamic modeling: an analysis of GDC-0973, a MEK inhibitor.

Clin Cancer Res 2012 Jun 10;18(11):3090-9. Epub 2012 Apr 10.

Drug Metabolism and Pharmacokinetics, Genentech, Inc., 1 DNA Way, MS 412a, South San Francisco, CA 94080, USA.

Purpose: GDC-0973 is a potent and selective mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor. Pharmacokinetic-pharmacodynamic (PK-PD) modeling was used to relate GDC-0973 plasma and tumor concentrations, tumor pharmacodynamics and antitumor efficacy to establish pharmacokinetic endpoints and predict active doses in the clinic.

Experimental Design: A PK-PD model was used to characterize GDC-0973 tumor disposition and in vivo potency in WM-266-4 xenograft mice. Simulations were conducted using the PK-PD model along with human pharmacokinetics to identify a target plasma concentration and predict active doses. In vivo potency and antitumor efficacy were characterized in A375 melanoma xenograft mice, and a population-based integrated PK-PD-efficacy model was used to relate tumor pharmacodynamics (%pERK decrease) to antitumor activity.

Results: GDC-0973 showed a sustained tumor pharmacodynamic response due to longer residence in tumor than in plasma. Following single doses of GDC-0973, estimated in vivo IC(50) values of %pERK decrease based on tumor concentrations in xenograft mice were 0.78 (WM-266-4) and 0.52 μmol/L (A375). Following multiple doses of GDC-0973, the estimated in vivo IC(50) value in WM-266-4 increased (3.89 μmol/L). Human simulations predicted a minimum target plasma concentration of 83 nmol/L and an active dose range of 28 to 112 mg. The steep relationship between tumor pharmacodynamics (%pERK decrease) and antitumor efficacy suggests a pathway modulation threshold beyond which antitumor efficacy switches on.

Conclusions: Clinical observations of %pERK decrease and antitumor activity were consistent with model predictions. This article illustrates how PK-PD modeling can improve the translation of preclinical data to humans by providing a means to integrate preclinical and early clinical data.
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http://dx.doi.org/10.1158/1078-0432.CCR-12-0445DOI Listing
June 2012

Hepatic organic anion transporting polypeptide transporter and thyroid hormone receptor interplay determines cholesterol and glucose homeostasis.

Hepatology 2011 Aug 26;54(2):644-54. Epub 2011 Jun 26.

Division of Clinical Pharmacology, Department of Medicine, The University of Western Ontario, London, ON, Canada.

Unlabelled: The role of organic anion transporting polypeptides (OATPs), particularly the members of OATP1B subfamily, in hepatocellular handling of endogenous and exogenous compounds is an important and emerging area of research. Using a mouse model lacking Slco1b2, the murine ortholog of the OATP1B subfamily, we have demonstrated previously that genetic ablation causes reduced hepatic clearance capacity for substrates. In this study, we focused on the physiological function of the hepatic OATP1B transporters. First, we studied the influence of the Oatp1b2 deletion on bile acid (BA) metabolism, showing that lack of the transporter results in a significantly reduced expression of Cyp7a1, the key enzyme of BA synthesis, resulting in elevated cholesterol levels after high dietary fat challenge. Furthermore, Slco1b2-/- mice exhibited delayed clearance after oral glucose challenge resulting from reduced hepatic glucose uptake. In addition to increased hepatic glycogen content, Slco1b2-/- mice exhibited reduced glucose output after pyruvate challenge. This is in accordance with reduced hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK) in knockout mice. We show that this phenotype is due to the loss of liver-specific Oatp1b2-mediated hepatocellular thyroid hormone entry, which then leads to reduced transcriptional activation of target genes of hepatic thyroid hormone receptor (TR), including Cyp7a1 and Pepck but also Dio1 and Glut2. Importantly, we assessed human relevance using a cohort of archived human livers in which OATP1B1 expression was noted to be highly associated with TR target genes, especially for glucose facilitating transporter 2 (GLUT2). Furthermore, GLUT2 expression was significantly decreased in livers harboring a common genetic polymorphism in SLCO1B1.

Conclusion: Our findings reveal that OATP1B-mediated hepatic thyroid hormone entry is a key determinant of cholesterol and glucose homeostasis.
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http://dx.doi.org/10.1002/hep.24391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164486PMC
August 2011

Membrane transporters in drug development.

Nat Rev Drug Discov 2010 Mar;9(3):215-36

Membrane transporters can be major determinants of the pharmacokinetic, safety and efficacy profiles of drugs. This presents several key questions for drug development, including which transporters are clinically important in drug absorption and disposition, and which in vitro methods are suitable for studying drug interactions with these transporters. In addition, what criteria should trigger follow-up clinical studies, and which clinical studies should be conducted if needed. In this article, we provide the recommendations of the International Transporter Consortium on these issues, and present decision trees that are intended to help guide clinical studies on the currently recognized most important drug transporter interactions. The recommendations are generally intended to support clinical development and filing of a new drug application. Overall, it is advised that the timing of transporter investigations should be driven by efficacy, safety and clinical trial enrolment questions (for example, exclusion and inclusion criteria), as well as a need for further understanding of the absorption, distribution, metabolism and excretion properties of the drug molecule, and information required for drug labelling.
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http://dx.doi.org/10.1038/nrd3028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3326076PMC
March 2010

Identification, expression, and functional characterization of full-length and splice variants of murine organic anion transporting polypeptide 1b2.

Mol Pharm 2009 Nov-Dec;6(6):1790-7

Division of Clinical Pharmacology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.

The family of organic anion transporting polypeptides (OATPs) plays an important role in mediating the cellular uptake of numerous endogenous and exogenous compounds. Members of this family include human OATP1B1 and OATP1B3, which have been widely studied and shown to be involved in the hepatic uptake of hormones, bile acids, and many clinically used drugs. However, little is known about the murine orthologue, Oatp1b2. We determined expression of mouse oatp1b2 mRNA and protein using real-time PCR and Western blot analysis. Interestingly, mRNA transcripts and protein were detectable in a number of tissues including kidney and stomach, and, not surprisingly, the highest expression was noted in liver. Cloning of the full coding region of oatp1b2 revealed the presence of two novel splice variants. Interestingly, these splice variants were significantly expressed in organs such as the kidney, but much less in liver. Heterologous expression of the full-length Oatp1b2 cDNA revealed that taurocholic acid, estrone 3-sulfate, estradiol 17beta-glucuronide and pravastatin are substrates of this transporter. The newly identified splice variants were unable to significantly transport substrate compounds due to defects in cell surface trafficking. Our findings of murine Oatp1b2 expression and function will likely aid in better defining species related differences in OATP transporter function and the use of mouse models to predict hepatic drug disposition in humans.
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http://dx.doi.org/10.1021/mp900030wDOI Listing
February 2010
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