Therapeutic Pharmacokinetics Research Articles

Overcoming Soluble Target Interference in Measurement of Total Bispecific Therapeutic Antibody Concentrations.

The measurement of therapeutic drug concentrations is used to assess drug exposure and the relationship between therapeutic pharmacokinetics (PK) and pharmacodynamics (PD), which help determine the optimal dose for patients. Ligand binding assays (LBAs) are often the method of choice for evaluation of drug concentration and use either the therapeutic target protein or antibodies to the therapeutic as capture and/or detection reagents. Due to the bivalency of antibody therapeutics, heterogeneous states of the drug/target complex can exist in the presence of soluble targets which can complicate measurement of unbound drug. In the case of bispecific antibodies, measurement of drug can be even more complicated and depend upon the levels of both targets to each arm. Measuring the total drug allows for PKPD modeling prediction of human dose projections in addition to overcoming challenges associated with measuring free drug for bispecific antibodies. Here, we present a study in which a sandwich ELISA format was used to measure total anti-KLK5/KLK7 antibody concentrations. This assay utilized a non-blocking anti-idiotype (ID) antibody to one arm of the antibody for capture and an antibody to target bound to the other arm of the antibody for detection. Our qualified assay showed acceptable precision, accuracy, dilutional linearity, and reproducibility and enabled detection of a total bispecific antibody at high levels of two targets. To confirm that our assay was detecting total drug, a subset of samples was evaluated in a generic total LC-MS/MS assay.

Therapeutic beta-lactam dosages and broad-spectrum antibiotics are associated with reductions in microbial richness and diversity in persons with cystic fibrosis

Persons with cystic fibrosis (PwCF) suffer from pulmonary exacerbations (PEx) related in part to lung infection. While higher microbial diversity is associated with higher lung function, the data on the impact of short-term antibiotics on changes in microbial diversity is conflicting. Further, Prevotella secretes beta-lactamases, which may influence recovery of lung function. We hypothesize that sub-therapeutic and broad spectrum antibiotic exposure leads to decreasing microbial diversity. Our secondary aim was to evaluate the concerted association of beta-lactam pharmacokinetics (PK), antibiotic spectrum, microbial diversity, and antibiotic resistance on lung function recovery using a pathway analysis. This was a retrospective observational study of persons with CF treated with IV antibiotics for PEx between 2016 and 2020 at Children’s National Hospital; respiratory samples and clinical information were collected at hospital admission for PEx (E), end of antibiotic treatment (T), and follow-up (F). Metagenomic sequencing was performed; PathoScope 2.0 and AmrPlusPlus were used for taxonomic assignment of sequences to bacteria and antibiotic resistance genes (ARGs). M/W Pharm was used for PK modeling. Comparison of categorical and continuous variables and pathway analysis were performed in STATA. Twenty-two PwCF experienced 43 PEx. The study cohort had a mean age of 14.6 years. Only 12/43 beta-lactam courses had therapeutic PK, and 18/43 were broad spectrum. A larger decrease in richness between E and T was seen in the therapeutic PK group (sufficient − 20.1 vs. insufficient − 1.59, p = 0.025) and those receiving broad spectrum antibiotics (broad − 14.5 vs. narrow − 2.8, p = 0.030). We did not detect differences in the increase in percent predicted forced expiratory volume in one second (ppFEV1) at end of treatment compared to PEx based on beta-lactam PK (sufficient 13.6% vs. insufficient 15.1%) or antibiotic spectrum (broad 11.5% vs. narrow 16.6%). While both therapeutic beta-lactam PK and broad-spectrum antibiotics decreased richness between PEx and the end of treatment, we did not detect longstanding changes in alpha diversity or an association with superior recovery of lung function compared with subtherapeutic PK and narrow spectrum antimicrobials.

Ex Vivo Dual Perfusion of the Human Placenta: Disease Simulation, Therapeutic Pharmacokinetics and Analysis of Off-Target Effects.

In recent years ex vivo dual perfusion of the human placental lobule is seeing an international renaissance in its application to understanding fetal health and development. Here, we discuss the methods and uses of this technique in the evaluation of (1) vascular function, (2) transplacental clearance, (3) hemodynamic and oxygenation changes associated with pregnancy complications on placental structure and function, and (4) placental toxicology and post-perfusion evaluation of tissue architecture.

Abstract 1066: Imipridone ONC201 efficacy in refractory multiple myeloma via Erk1/2 inhibition and pro-apoptotic Bim upregulation: single agent and combinatorial approaches

Abstract Disease relapse and drug resistance occurs in the majority of multiple myeloma (MM) patients despite improvements offered by new treatments. There is an urgent unmet need for new therapies that can overcome drug resistance and prolong patient survival after failure of standard-of-care. ONC201, founding member of the impridone class of compounds, has robust preclinical efficacy in a variety of tumor types. A first-in-human ONC201 clinical study has demonstrated exceptional safety, therapeutic pharmacokinetics and evidence of tumor engagement that has led to several Phase I/II advanced cancer studies. Given the pronounced sensitivity of B-cell lymphomas to ONC201, we assessed the efficacy of ONC201 in MM preclinical models. We treated human MM cell lines and patient-derived cells isolated from bone marrow aspirates with ONC201 for 72 hours. ONC201 treatment decreased MM cell viability in CellTiter-Glo assays, with IC50 values that were 1 μM to 1.5 μM, even in high risk MM cell line RPMI8226. Consistent with prior reports, the efficacy of ONC201 was independent of TP53 status, as MM.1S or NCI-H929 cells with wild-type TP53 and OPM-2 or RPMI8226 with mutated TP53 had a similar sensitivity towards ONC201. Additionally, ONC201 was equally effective in paired MM cell lines with TP53 wild type or knockout. Western blot analysis showed increased apoptosis, cleavage of caspase-9, caspase-3, and PARP. We also found that ONC201 induced expression of the pro-apoptotic protein Bim in MM cells, which can occur downstream of ERK inactivation. shRNA knockdown of Bim expression in MM cells abrogated ONC201-induced apoptosis in annexin-V binding assays. Phosphorylation of Bim at Ser69 by Erk1/2 has been shown to promote proteasomal degradation of Bim. In accordance with this mechanism, we observed that ONC201 treatment reduced levels of phosphorylated Erk1/2, an indicator of Erk1/2 kinase activity, and downregulated Bim pSer69. In addition, ONC201 induced apoptosis in dexamethasome-, bortezomib-, and carfilzomib-resistant MM cell lines with the same efficacy as in wild-type cells. As a rational strategy to increase the efficacy of ONC201 by enhancing its inhibition of proteasome-mediated Bim degradation, we tested combinations of ONC201 with proteasome inhibitors. Synergistic reduction in cell viability and enhanced Bim expression and PARP cleavage was observed with ONC201 in combination with bortezomib or carfilzomib in MM cells. The combination of ONC201 and bortezomib enhanced the levels of Bim and cleaved PARP in MM cells. Overall, these findings demonstrate that ONC201 inhibits the Erk1/2 signaling pathway and induces Bim expression to induce apoptosis in MM regardless of p53 status and resistance to standard-of-care therapies. Our studies provide a strong rationale for clinical trials of ONC201 as a single agent or in combination with approved drugs in relapsed/refractory MM. Citation Format: Yongsheng Tu, Jin He, Huan Liu, Richard Eric Davis, Robert Z. Orlowski, Varun Vijay Prabhu, Joshua Allen, Jing Yang. Imipridone ONC201 efficacy in refractory multiple myeloma via Erk1/2 inhibition and pro-apoptotic Bim upregulation: single agent and combinatorial approaches [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1066. doi:10.1158/1538-7445.AM2017-1066

Improving Brain Drug Targeting Through Exploitation of The Nose-to- Brain Route: A Physiological and Pharmacokinetic Perspective

With an ageing population and increasing prevalence of central-nervous system (CNS) disorders new approaches are required to sustain the development and successful delivery of therapeutics into the brain and CNS. CNS drug delivery is challenging due to the impermeable nature of the brain microvascular endothelial cells that form the blood-brain barrier (BBB) and which prevent the entry of a wide range of therapeutics into the brain. This review examines the role intranasal delivery may play in achieving direct brain delivery, for small molecular weight drugs, macromolecular therapeutics and cell-based therapeutics, by exploitation of the olfactory and trigeminal nerve pathways. This approach is thought to deliver drugs into the brain and CNS through bypassing the BBB. Details of the mechanism of transfer of administrated therapeutics, the pathways that lead to brain deposition, with a specific focus on therapeutic pharmacokinetics, and examples of successful CNS delivery will be explored.