Risk assessment of drug-drug interaction potential for bintrafusp alfa with cytochrome P4503A4 substrates: A totality of evidence approach.

Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of TGF-ßRII (a TGF-ß "trap") fused to a human IgG1 mAb blocking PD-L1, is being evaluated for efficacy and safety in solid tumor indications as monotherapy and in combination with small-molecule drugs. We evaluated the perpetrator drug-drug interaction (DDI) potential of bintrafusp alfa via cytochrome P4503A4 (CYP3A4) enzyme modulation, which is responsible for the metabolism of a majority of drugs. The holistic approach included (1) evaluation of longitudinal profiles of cytokines implicated in CYP3A4 modulation and serum 4ß-hydroxycholesterol, an endogenous marker of CYP3A4 activity, in a phase I clinical study, and (2) transcriptomics analysis of the CYP3A4 mRNA levels vs the TGFB gene expression signature in normal hepatic tissues. Bintrafusp alfa was confirmed not to cause relevant proinflammatory cytokine modulation or alterations in 4ß-hydroxycholesterol serum concentrations in phase I studies. Transcriptomics analyses revealed no meaningful correlations between TGFB gene expression and CYP3A4 mRNA expression, supporting the conclusion that the risk of CYP3A4 enzyme modulation due to TGF-ß neutralization by bintrafusp alfa is low. Thus, bintrafusp alfa is not expected to have DDI potential as a perpetrator with co-administered drugs metabolized by CYP3A4; this information is relevant to clinical evaluations of bintrafusp alfa in combination settings.

Standardized Mixed-Meal Tolerance and Arginine Stimulation Tests Provide Reproducible and Complementary Measures of ß-Cell Function: Results From the Foundation for the National Institutes of Health Biomarkers Consortium Investigative Series.

OBJECTIVE: Standardized, reproducible, and feasible quantification of ß-cell function (BCF) is necessary for the evaluation of interventions to improve insulin secretion and important for comparison across studies. We therefore characterized the responses to, and reproducibility of, standardized methods of in vivo BCF across different glucose tolerance states. RESEARCH DESIGN AND METHODS: Participants classified as having normal glucose tolerance (NGT; n = 23), prediabetes (PDM; n = 17), and type 2 diabetes mellitus (T2DM; n = 22) underwent two standardized mixed-meal tolerance tests (MMTT) and two standardized arginine stimulation tests (AST) in a test-retest paradigm and one frequently sampled intravenous glucose tolerance test (FSIGT). RESULTS: From the MMTT, insulin secretion in T2DM was >86% lower compared with NGT or PDM (P < 0.001). Insulin sensitivity (Si) decreased from NGT to PDM (∼50%) to T2DM (93% lower [P < 0.001]). In the AST, insulin secretory response to arginine at basal glucose and during hyperglycemia was lower in T2DM compared with NGT and PDM (>58%; all P < 0.001). FSIGT showed decreases in both insulin secretion and Si across populations (P < 0.001), although Si did not differ significantly between PDM and T2DM populations. Reproducibility was generally good for the MMTT, with intraclass correlation coefficients (ICCs) ranging from ∼0.3 to ∼0.8 depending on population and variable. Reproducibility for the AST was very good, with ICC values >0.8 across all variables and populations. CONCLUSIONS: Standardized MMTT and AST provide reproducible and complementary measures of BCF with characteristics favorable for longitudinal interventional trials use.

Pharmacokinetics and Disposition of the Thiouracil Derivative PF-06282999, an Orally Bioavailable, Irreversible Inactivator of Myeloperoxidase Enzyme, Across Animals and Humans.

The thiouracil derivative PF-06282999 [2-(6-(5-chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide] is an irreversible inactivator of myeloperoxidase and is currently in clinical trials for the potential treatment of cardiovascular diseases. Concerns over idiosyncratic toxicity arising from bioactivation of the thiouracil motif to reactive species in the liver have been largely mitigated through the physicochemical (molecular weight, lipophilicity, and topological polar surface area) characteristics of PF-06282999, which generally favor elimination via nonmetabolic routes. To test this hypothesis, pharmacokinetics and disposition studies were initiated with PF-06282999 using animals and in vitro assays, with the ultimate goal of predicting human pharmacokinetics and elimination mechanisms. Consistent with its physicochemical properties, PF-06282999 was resistant to metabolic turnover from liver microsomes and hepatocytes from animals and humans and was devoid of cytochrome P450 inhibition. In vitro transport studies suggested moderate intestinal permeability and minimal transporter-mediated hepatobiliary disposition. PF-06282999 demonstrated moderate plasma protein binding across all of the species. Pharmacokinetics in preclinical species characterized by low to moderate plasma clearances, good oral bioavailability at 3- to 5-mg/kg doses, and renal clearance as the projected major clearance mechanism in humans. Human pharmacokinetic predictions using single-species scaling of dog and/or monkey pharmacokinetics were consistent with the parameters observed in the first-in-human study, conducted in healthy volunteers at a dose range of 20-200 mg PF-06282999. In summary, disposition characteristics of PF-06282999 were relatively similar across preclinical species and humans, with renal excretion of the unchanged parent emerging as the principal clearance mechanism in humans, which was anticipated based on its physicochemical properties and supported by preclinical studies.