Pharmacokinetic-Pharmacodynamic Modeling in Pediatric Drug Development, and the Importance of Standardized Scaling of Clearance.

Pharmacokinetic/pharmacodynamic (PKPD) modeling is important in the design and conduct of clinical pharmacology research in children. During drug development, PKPD modeling and simulation should underpin rational trial design and facilitate extrapolation to investigate efficacy and safety. The application of PKPD modeling to optimize dosing recommendations and therapeutic drug monitoring is also increasing, and PKPD model-based dose individualization will become a core feature of personalized medicine. Following extensive progress on pediatric PK modeling, a greater emphasis now needs to be placed on PD modeling to understand age-related changes in drug effects. This paper discusses the principles of PKPD modeling in the context of pediatric drug development, summarizing how important PK parameters, such as clearance (CL), are scaled with size and age, and highlights a standardized method for CL scaling in children. One standard scaling method would facilitate comparison of PK parameters across multiple studies, thus increasing the utility of existing PK models and facilitating optimal design of new studies

Phase Ib study of ribociclib plus letrozole in a subset of Asian patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer

Background: MONALEESASIA is an ongoing Phase Ib dose-escalation/-expansion study evaluating RIB + LET in a subset of Asian pts from Hong Kong and Singapore with HR+, HER2–ABC. Methods: Postmenopausal pts from Hong Kong and Singapore with HR+, HER2– ABC and no prior systemic therapy for ABC received RIB (400 or 600 mg/day; 3-weeks-on/1-week-off) + LET (2.5 mg/day; continuous). Dose escalation used a Bayesian Logistic Regression Model with overdose control. The primary endpoint was to determine the maximum tolerated dose (MTD)/recommended Phase II dose (RP2D); secondary endpoints included safety and pharmacokinetic (PK) profile. Blood samples for PK non-compartmental analysis were collected on Days 1 and 21 of Cycle 1 from pre-dose to 24 h post-dose. Results: At data cut-off (Jan 16, 2017), 26 pts were enrolled (RIB 400 mg: n = 6; 600 mg: n = 20). One dose-limiting toxicity was observed at 600 mg (Grade 3 increased alanine transaminase [ALT]); the MTD/RP2D was RIB 600 mg/day (3-weeks-on/1-week-off) + LET 2.5 mg/day (continuous). Grade 3/4 treatment-related adverse events (TRAEs) occurred in 4/6 pts at 400 mg and 17/20 pts at 600 mg during the dose-escalation and -expansion parts. The most common Grade 3/4 TRAEs (≥20% in either cohort; 400 mg vs 600 mg) were decreased neutrophil count (n = 3 vs n = 7), neutropenia (n = 1 vs n = 6), increased ALT (n = 1 vs n = 4), and increased aspartate transaminase (n = 0 vs n = 4). After a single dose (Cycle 1 Day 1) and at steady state (Cycle 1 Day 21), absorption of both RIB and LET was rapid (Table); increases in RIB exposure were dose dependent. Conclusions: The MTD/RP2D was declared as RIB 600 mg/day (3-weeks-on/1-week-off) + LET 2.5 mg/day (continuous) in Asian pts from Hong Kong and Singapore with HR+, HER2– ABC. Preliminary safety and PK data are consistent with prior observations in non-Asian pts.link_to_subscribed_fulltex

RNA-Seq-based analysis of the physiologic cold shock-induced changes in Moraxella catarrhalis gene expression

BACKGROUND: Moraxella catarrhalis, a major nasopharyngeal pathogen of the human respiratory tract, is exposed to rapid downshifts of environmental temperature when humans breathe cold air. The prevalence of pharyngeal colonization and respiratory tract infections caused by M. catarrhalis is greatest in winter. We investigated how M. catarrhalis uses the physiologic exposure to cold air to regulate pivotal survival systems that may contribute to M. catarrhalis virulence. RESULTS: In this study we used the RNA-seq techniques to quantitatively catalogue the transcriptome of M. catarrhalis exposed to a 26 °C cold shock or to continuous growth at 37 °C. Validation of RNA-seq data using quantitative RT-PCR analysis demonstrated the RNA-seq results to be highly reliable. We observed that a 26 °C cold shock induces the expression of genes that in other bacteria have been related to virulence a strong induction was observed for genes involved in high affinity phosphate transport and iron acquisition, indicating that M. catarrhalis makes a better use of both phosphate and iron resources after exposure to cold shock. We detected the induction of genes involved in nitrogen metabolism, as well as several outer membrane proteins, including ompA, m35-like porin and multidrug efflux pump (acrAB) indicating that M. catarrhalis remodels its membrane components in response to downshift of temperature. Furthermore, we demonstrate that a 26 °C cold shock enhances the induction of genes encoding the type IV pili that are essential for natural transformation, and increases the genetic competence of M. catarrhalis, which may facilitate the rapid spread and acquisition of novel virulence-associated genes. CONCLUSION: Cold shock at a physiologically relevant temperature of 26 °C induces in M. catarrhalis a complex of adaptive mechanisms that could convey novel pathogenic functions and may contribute to enhanced colonization and virulence