How to Advance your Preclinical Research Using Mouse Data to Establish PK/PD Relationships  

Feb 24, 2025

The major objective of early drug development is to select the most promising compounds and establish safe and effective doses and dosing regimens. To do so, an analysis of both the pharmacokinetic (PK) and pharmacodynamic (PD) properties of your novel compound needs to be performed.  Well-designed PK and PD studies performed early on in your drug development journey help you not only with compound selection but ultimately pave the way for an efficient clinical development strategy. In this blog post, we outline how using mouse data to establish PK/PD relationships, coupled with InnoSer’s expertise as a leading European preclinical drug development CRO, can help you navigate the hurdles of drug development.  

What Is the Difference Between PK and PD?  

The goal of PK and PD compound screening is to evaluate the relationship between the concentration of a drug in the body (PK), and the drug’s biological effects (PD). While PK study data provide you information about your drug’s absorption, distribution, metabolism and excretion (ADME) dynamics, PD study data provide you with information relating to drug-receptor binding, cellular activity, intracellular mechanisms and structure-activity relationships of the drug itself. Moreover, PD markers are usually very specific to the mechanism of action of the drug, and the measured PD response is usually a direct measure of the target modulation.  

Poor ADME properties can undermine an otherwise promising drug. In order to obtain a reliable drug concentration (PK) – effect (PD) relationship, experts at InnoSer recommend design and implementation of robust study plans to obtain a full pharmacological profile of your compound. Toxicokinetic (TK) studies may also be performed to correlate any findings of toxicity with a corresponding level of drug exposure and can help to reduce the number of laboratory animals used in line with the  3Rs guidelines (replacement, reduction and refinement).  

Using Mouse Data to Establish PK/PD Relationships 

Using mouse data to establish PK/PD relationships provides critical insights that help bridge the gap between the preclinical and clinical phases. Additionally, at InnoSer PK/PD screening studies can also be performed in rats, offering complementary data for a more comprehensive understanding. PK/PD studies can be performed in wildtype of transgenic rodents and disease models to give you clear insight before engaging efficacy studies. Such studies can provide you with a wealth of information, such as:  

  • Inform you whether further drug re-formulations and/or optimizations are necessary 
  • Whether you should prioritise the drug with most favourable PK/PD profile to move to preclinical testing 

 

Using mouse data to establish PK/PD relationships, the different data types that you can typically obtain from PK/PD analyses include:  

  • Dose-response relationship data 
  • Maximum effect (Emax)  
  • Potency (EC50)  
  • Maximum drug concentration (Cmax)  
  • Time to maximum concentration (Tmax)  
  • t1/2 elimination (terminal elimination half-life)  
  • Total drug exposure via area under the curve (AUC)   
  • Data on receptor binding, biochemical effects, and clinical outcomes for pharmacodynamics  
  • Therapeutic window (range between the minimum effective concentration and the maximum safe concentration)  

 

Partnering with InnoSer ensures that you receive high-quality PK/PD services to make informed decisions in your drug development process. Our expert team provides tailored study designs, advanced analytical support, and comprehensive data interpretation to help you confidently move your compound toward clinical success. 

Dosing Routes and Techniques for Rodent PK Screening Studies 

The selection of appropriate dosing routes is a critical factor in PK studies, as it influences drug absorption, biodistribution, and overall efficacy. Common administration routes at InnoSer include: 

  • Intravenous (IV): Provides immediate systemic circulation and is commonly used for bioavailability and clearance studies. 
  • Intramuscular (IM): Enables sustained release and localized drug delivery. 
  • Subcutaneous (SC): Offers a less invasive route with slower absorption rates, commonly used for biologics. 
  • Oral (PO): Mimics human drug intake but is influenced by first-pass metabolism. 
  • Intrathecal (IT) and Intracerebroventricular (ICV): Facilitate direct delivery to the central nervous system for neurological therapeutics. 
  • Intraperitoneal (IP): Frequently used in rodent models for systemic drug administration when IV access is challenging. 
  • Intraspinal delivery: Administer compounds directly to spinal cord regions. 
  • Intracereberal delivery into different brain regions: depending on target brain region, InnoSer can perform stereotatic injections to locally deliver compounds.  
  • Chronic cannulation into cisterna magna ICM: chronic cannulation studies into cisterna magna are possible at InnoSer in rats. 

 

Using Mouse Data To Establish PK/PD Relationships in Specialized PK/PD Studies 

PK/PD studies are not one-size-fits-all; specialized approaches are required depending on the drug modality. InnoSer provides tailored PK/PD study designs that address the unique characteristics of various drug classes, including small molecules, biologics, and gene therapies. 

In vivo PK/PD Studies For Gene Therapy Approaches  

Gene therapies introduce unique PK and PD challenges due to their long-lasting effects and complex delivery mechanisms. Unlike small molecules or biologics, gene therapies often require precise vector optimization, biodistribution assessment, and prolonged PK monitoring (1). Some of the key challenges and considerations for PK/PD studies in gene therapy include: 

  • Vector delivery and biodistribution: Understanding how viral and non-viral vectors distribute within tissues is critical for efficacy and safety. 
  • Route of administration: fine-tuning of administration strategies is the key to unlock the full potential of gene therapies. Considerations such as clinical applicability (i.e., invasive delivery procedures or IV), cost and scaling of production (i.e., higher in cases of IV), potential off-target effects and immune-related risks in case of higher systemic exposures need to be evaluated in the preclinical research phases.  
  • Expression kinetics: Gene therapy effects may take days to weeks to manifest, requiring extended PK/PD monitoring. 

 

Readouts and Approaches for Gene Therapy PK Screening Studies 

At InnoSer, we’re specialized in helping you optimize gene therapies tailored to your therapeutic modality (e.g., RNA-based therapeutics, ASOs, CRISPR-Cas9), delivery  systems (e.g., AAV-vectors, lentiviral or adeno-associated viral vectors, non-viral nanoparticles such as LNPs), administration routes (IV, ICV, intrathecal), as well as experience in medical devices to enhance BBB penetration and region-specific delivery. Key readouts and approaches for gene therapy PK screening that InnoSer offers include:  

Optimization of administration routes and dosages 

  • Comparing different administration routes (e.g., IV versus ICV administration). 
  • Direct organ delivery strategies evaluation (such as kidney, relevant for genetic diseases such as ADPKD – read more here).  
  • Testing single versus repeated dosing schedules. 
  • Testing prophylactic and/or treatment strategies efficacy. 

Biodistribution Analysis 

  • In vivo imaging (bioluminescence/fluorescence) to assess real-time gene expression and distribution. 
  • Detect vector DNA in target and off-target tissues. 

Transgene Expression and Protein Production 

  • RT-qPCR/ddPCR to measure transgene mRNA levels. 
  • Western Blot/ELISA to quantify transgene-encoded protein levels. 
  • Immunohistochemistry (IHC) to localize transgene expression. 

Functional Readouts 

  • Phenotypic assessments to evaluate therapeutic effects on disease models. 

Immunology readouts 

  • Local inflammatory reactions (e.g., via IHC), immunogenicity (flow cytometry immune cell profiling), inflammatory cytokine MSD/ELISA panels to study adaptive and innate immunity 

 

In a representative experiment, InnoSer evaluated the efficiency of CRISPR/Cas9-mediated gene editing using Ai9 mice (Figure 1). 

Example of a way on how to use mouse data to establish PK/PD relationship in which we assessed the biodistribution of CRISPR CAS 9 therapy

FIGURE 1. Gene editing efficacy optimizing experiment example. The efficiency of CRISPR/Cas9-mediated gene editing can be evaluated by using strains such as Ai9. The Ai9 strain enables the quantification of fluorescent signal in the targeted muscle tissue following intramuscular injection of iTOP® CRISPR/Cas9 targeted to remove the STOP codon (A), which normally prevents the expression of tdTomato. Following CRISPR/Cas9-mediated recombination (B), the skeletal muscle of the Ai9 strain transcribe the tdTomato gene. The representative image (C) underscores the efficiency of CRISPR/Cas9-mediated gene editing following optimization studies. Complementary gene and protein expression analysis with longitudinal in vivo luminescent imaging follow-up in turn provide highly relevant insight in biodistribution and gene editing efficiency. 

In Vivo PK/PD Studies for Therapeutic Antibodies 

Historically, PK/PD modelling has been applied in the development of small molecule drugs; however, modelling has more recently been successfully applied to characterize the efficacy and disposition of biotherapeutic drugs such as monoclonal antibodies, bispecific antibodies or antibody-drug conjugates (ADCs). The PK and PD of large molecules differ in several aspects from those of small molecules. 

Therapeutic antibodies often exhibit high specificity for human targets. Therefore, antibodies designed to recognize human proteins may fail to interact with their mouse or rat counterparts, and occasionally, even non-human primate proteins. To address these challenges, PK/PD studies need to be performed in advanced humanized mouse models. InnoSer has extensive experience running sponsor studies in specialized mouse models that express human or human-like features in different parts of their biology tailored for these purposes.  

 

Using Advanced Humanized Mouse Models for PK Studies 

Most therapeutic mAbs are immunoglobulin G (IgG) subclasses, IgG1 and IgG2. The neonatal Fc receptor (FCRN; also known as FCGRT) plays a central role in IgG clearance by protecting antibodies from degradation, thus largely influencing and prolonging their PK profile. However, due to species differences in antibody binding to the FCRN, PK studies in wild-type (WT) mice do not generate a reliable PK profile.  

Therefore, humanized mouse models with human FcRN receptors are pivotal for accurately predicting the PK profile of therapeutic antibodies. As these mice express the human FcRn receptor instead of the mouse version, you can easily and more predictively:  

  • Evaluate antibody clearance: Human FcRn mice provide insights into the half-life and clearance of antibodies in humans. 
  • Enhance translatability: These models improve the predictiveness of preclinical PK assessments. 

Transgenic humanized mouse models serve as a robust platform for selecting promising leads and predicting clinical PK parameters of therapeutic antibody candidates. InnoSer offers PK studies in humanized target-specific mouse models (such as FcRN, hTNFR2 mice etc.,)or humanized immune system mice. Reach out to our expert pharmacology study directors who will advise you on the most suitable rodent model for your PK rodent screening studies.  

 

Partnering Up with a Preclinical CRO for PK/PD Screening Studies  

Collaborating with a Contract Research Organization (CRO) offers several key advantages for conducting PK/PD analyses. Partnering with a CRO gives you access to a wealth of expertise and resources that can significantly enhance the quality and efficiency of your studies.  

By delegating the execution of preclinical studies to a trusted partner, your organization can concentrate on strategic decision-making and advancing drug candidates to the next phase of development. By leveraging the resources of an external organization, you can reduce the need for in-house capabilities and accelerate project timelines. 

 

What Sets InnoSer Apart for PK/PD Services? 

As a European preclinical drug development CRO, InnoSer offers comprehensive support for your PK/PD studies, including:  

  • Customized solutions: At InnoSer we can accommodate both low-volume (one-time) and large-volume (recurrent) PK/PD studies. We take care of assay validation for your investigational drugs. With large volume we work with fixed turnaround times (TAT) combined with animals on stand-by to enable you fast study initiation times, enabling large scale rodent PK screening studies. 
  • Colony breeding and maintenance: InnoSer regularly houses and/or breeds specific humanized mouse models as part of it’s PK/PD services portfolio, allowing you to benefit from faster study start times. 
  • Integration of PK/PD screening studies and efficacy studies: Performing your PK/PD screening studies at InnoSer allows you to efficiently progress to efficacy studies without study delays.  
  • Expertise: InnoSer’s expert pharmacology study directors take into account your compound’s MoA and thoroughly discusses with you the study the most appropriate study design, bleeding schemes, gender, strain, and dosing routes.  
  • Communication: With InnoSer you don’t lose ownership of your own projects, as study results and/or any unexpected findings are always communicated with you. Raw data are shared via safe data-sharing platforms for quick study updates. 
  • Experience working with different matrices and compounds: InnoSer has experience working with different biological matrices including serum, plasma, urine, saliva, CSF. Compounds include small molecules, and large macromolecules (e.g., antibodies).   
  • Mouse models: InnoSer can work with genetically modified PK models, especially relevant for antibody therapeutics PK evaluation (e.g., using FcRN humanized mice for antibody development).  

 

Using Mouse Data to Establish PK/PD Relationships – Conclusion 

PK/PD studies in mice are a cornerstone of preclinical drug development, providing you with crucial data needed to make informed decisions about dosing, efficacy, and safety. With expertise in conducting rodent PK screens, InnoSer is your trusted partner in advancing your therapeutic research. 

Contact us today to learn how we can support your next breakthrough.