Review: Role of Model-Informed Drug Development Approaches in the Lifecycle of Drug Development and Regulatory Decision-Making.

Model-informed drug development (MIDD) is a powerful approach to support drug development and regulatory review. There is a rich history of MIDD applications at the U.S. Food and Drug Administration (FDA). MIDD applications span across the life cycle of the development of new drugs, generics, and biologic products. In new drug development, MIDD approaches are often applied to inform clinical trial design including dose selection/optimization, aid in the evaluation of critical regulatory review questions such as evidence of effectiveness, and development of policy. In the biopharmaceutics space, we see a trend for increasing role of computational modeling to inform formulation development and help strategize future in vivo studies or lifecycle plans in the post approval setting. As more information and knowledge becomes available pre-approval, quantitative mathematical models are becoming indispensable in supporting generic drug development and approval including complex generic drug products and are expected to help reduce overall time and cost. While the application of MIDD to inform the development of cell and gene therapy products is at an early stage, the potential for future application of MIDD include understanding and quantitative evaluation of information related to biological activity/pharmacodynamics, cell expansion/persistence, transgene expression, immune response, safety, and efficacy. With exciting innovations on the horizon, broader adoption of MIDD is poised to revolutionize drug development for greater patient and societal benefit.

Heterogeneity in treatment effects across diverse populations.

Differences in patient characteristics, including age, sex, and race influence the safety and effectiveness of drugs, biologic products, and medical devices. Here we provide a summary of the topics discussed during the opening panel at the 2018 Johns Hopkins Center for Excellence in Regulatory Science and Innovation symposium on Assessing and Communicating Heterogeneity of Treatment Effects for Patient Subpopulations: Challenges and Opportunities. The goal of this session was to provide a brief overview of FDA-regulated therapeutics, including drugs, biologics and medical devices, and some of the major sources of heterogeneity of treatment effects (HTE) related to patient demographics, such as age, sex and race. The panel discussed the US Food and Drug Administration's role in reviewing and regulating drugs, devices, and biologic products and the challenges associated with ensuring that diverse patient populations benefit from these therapeutics. Ultimately, ensuring diverse demographic inclusion in clinical trials, and designing basic and clinical research studies to account for the intended patient population's age, sex, race, and genetic factors among other characteristics, will lead to better, safer therapies for diverse patient populations.

Personalized Cardiovascular Medicine Today: A Food and Drug Administration/Center for Drug Evaluation and Research Perspective.

Over the past decade, personalized medicine has received considerable attention from researchers, drug developers, and regulatory agencies. Personalized medicine includes identifying patients most likely to benefit and those most likely to experience adverse reactions in response to a drug, and tailoring therapy based on pharmacokinetics or pharmacodynamic response, as well. Perhaps most exciting is finding ways to identify likely responders through genetic, proteomic, or other tests, so that only likely responders will be treated. However, less precise methods such as identifying historical, demographic, or other indicators of increased or reduced responsiveness are also important aspects of personalized medicine. The cardiovascular field has not used many genetic or proteomic markers, but has regularly used prognostic variables to identify likely responders. The development of biomarker-based approaches to personalized medicine in cardiovascular disease has been challenging, in part, because most cardiovascular therapies treat acquired syndromes, such as acute coronary syndrome and heart failure, which develop over many decades and represent the end result of several pathophysiological mechanisms. More precise disease classification and greater understanding of individual variations in disease pathology could drive the development of targeted therapeutics. Success in designing clinical trials for personalized medicine will require the selection of patient populations with attributes that can be targeted or that predict outcome, and the use of appropriate enrichment strategies once such attributes are identified. Here, we describe examples of personalized medicine in cardiovascular disease, discuss its impact on clinical trial design, and provide insight into the future of personalized cardiovascular medicine from a regulatory perspective.

Predicted impact of various clinical practice strategies on cardiovascular risk for the treatment of hypertension: a clinical trial simulation study.

Hypertension control rate in the US is low with the current clinical practice (JNC 7) and cardiovascular disease (CVD) remain is the leading cause of morbidity and mortality. A 6-month clinical trial simulation case study testing different virtual clinical practice strategies was performed in an attempt to increase the control rate. The CVD risk was calculated using the Framingham CVD risk model at baseline and 6 months post-treatment. The estimated CVD events for the baseline patient sample without any treatment was 998 (95% CI: 967-1,026) over 6 months in 100,000 patients. Treating these patients for 6 months with current clinical practice, high dose strategy, high dose with low target BP strategy resulted in a reduction in CVD events of 191(95% CI: 169-205), 284 (95% CI: 261-305), and 353 (95% CI: 331-375), respectively. Hence the two alternative strategies resulted in an increase in treatment effect by 49% (95%CI: 44-59%) and 85% (95%CI: 79-99%), respectively. The increased safety with the current low dose strategy may potentially be offset by increased CVD risk in the time necessary to control hypertension.

Statin Drug-Drug Interactions: Pharmacokinetic Basis of FDA Labeling Recommendations and Comparison Across Common Tertiary Clinical Resources.

Statins are widely prescribed and highly susceptible to pharmacokinetic (PK)-based drug-drug interactions (DDIs). To date, there has not been a comprehensive analysis of the basis upon which statin DDI recommendations in US Food and Drug Administration (FDA) prescribing information (PI) are derived. We have conducted such an analysis. We also assessed the degree of concordance of statin DDI recommendations in FDA PI and those provided in common tertiary clinical resources. We catalogued statin DDI information, including PK data and management recommendations, for statin precipitant drugs approved from 2010 to 2021, available from FDA PI and tertiary clinical resource databases. Recommendations were categorized and mapped with associated PK data to assess consistency in the PK basis for labeling recommendations. From the 80 precipitant drugs evaluated, 180 statin DDIs were identified in FDA PI. Dedicated clinical DDI studies were conducted for 54% (n = 97) of these DDIs and 34% (n = 61) of DDI recommendations were extrapolated from clinical data with other statins. Overall, we found that PK-based statin recommendations were consistent across PI. These findings highlight regulatory precedence for translating information across statins without conducting dedicated clinical DDI studies, which may support future efforts toward streamlining the approach to investigation and labeling of statin DDIs. In addition, with the exception of some notable discrepancies, general concordance was observed between FDA and tertiary resources regarding "Dose Adjustment" and "Avoid Coadministration" recommendations. However, further analyses are warranted across other DDI pairs to determine whether discordance can routinely lead to different clinical recommendations depending on the drug information resource.

Clinical Pharmacology Approaches to Support Approval of New Routes of Administration for Therapeutic Proteins.

Intravenous or subcutaneous routes of administration (ROAs) are common dosing routes for therapeutic proteins. Eleven therapeutic proteins with approval for one ROA have subsequently received approval for a second ROA. The clinical programs supporting the second ROA consistently leveraged data from the first ROA and included studies that characterized the pharmacokinetics (PKs) of the drug administered by the new ROA to identify an appropriate dosage regimen. The selected dosing regimen was then further evaluated in clinical trials designed with various primary end points. All programs implemented model-informed drug development approaches to ensure that the selected regimens would achieve comparable systemic exposures (PK-based bridging) or pharmacodynamic (PD) responses (PD-based bridging) as the reference ROA. To support the approval of a second ROA, these programs either demonstrated noninferiority in PK, PD, and/or clinical end points for the second ROA, or established efficacy and safety through a comparison to a placebo treatment. The accumulative examples showed that clinical trials which provided the primary evidence to support approvals of the second ROA generally demonstrated noninferiority in the systemic exposures regardless of being specified as an end point or not in the study protocols. The experience to date supports the use of PK- and PD-based bridging approaches not only in the selection of dosing regimens for a second ROA to be tested in clinical studies, but also for providing evidence of effectiveness to support approval, when appropriate.

Inclusion of Subjects who are Obese in Drug Development: Current Status and Opportunities.

The prevalence of obesity has grown tremendously in recent years and this population has an increased risk of disease comorbidities. The presence of disease comorbidities requires treatment interventions and proper dosing guidelines. However, drug development programs often do not have adequate representation of individuals who are obese in clinical trials, leaving gaps in the understanding of treatment response leading to a lack of adequate individualization options. Based on a recent survey of approved drug product package inserts, very few approved products included specific dosing based on obesity, in both adults and pediatrics. Reasons for the limited information on patients who are obese may include the under-reporting of information regarding such patients and a lack of clinical trial diversity in enrolling patient groups in whom obesity or obesity-related comorbidities are more prevalent. An inadvertent impact of the practice of exclusion of subsets of patients with some comorbidities in clinical trials may play a role in the reduced enrollment of individuals who are obese. Recently, regulatory authorities have taken specific initiatives to promote clinical trial diversity, including engaging with stakeholders and publishing regulatory guidance. These guidance documents highlight the need to enroll diverse clinical trial populations and provide recommendations on concepts related to drug development for obese populations. Such efforts will help to address the gap in information regarding drug response and dosing in patients who are obese.

US FDA Postmarketing Requirements and Commitments: A Systematic Assessment of Clinical Pharmacology Studies and Their Impact on US FDA Prescribing Information.

Many of the conditions for the safe and effective use of new molecular entities (NMEs) are understood at the time of initial drug approval. However, some remaining knowledge gaps can be addressed after drug approval through postmarketing requirements (PMRs) or commitments (PMCs) established by the US Food and Drug Administration (FDA). Our objective was to conduct an assessment of clinical pharmacology-related PMRs and PMCs established at the time of approval and evaluate the impact of fulfilled PMRs and PMCs on prescription information (PI). This analysis included clinical pharmacology-related PMRs and PMCs established for NMEs approved between 2009 and 2020. Of the 1171 PMRs and PMCs, over one-third were clinical pharmacology-related. Of these, 46% were to evaluate drug interactions, 16% were to evaluate drug dosing in patients with hepatic impairment, and 10% were related to dose. The majority (57%) of PMRs and PMCs were fulfilled at the time of analysis, with a median time to fulfillment of approximately 2.3 years. The majority (94%) of the fulfilled PMRs and PMCs, either with or without a PI revision, resulted in new or modified instructions for use or supported existing instructions for use. This is the first time that clinical pharmacology-related PMRs and PMCs have been catalogued and analyzed to understand their impact on PI. An understanding of the knowledge gaps that exist at the time of drug approval could inform the most effective and efficient methods for evidence generation prior to and after new drug approval.

Pediatric dosing for locally acting drugs in submissions to the U.S. Food and Drug Administration between 2002 and 2020.

Deriving pediatric doses for locally acting drugs (LADs) presents a unique challenge because limited systemic exposure hinders commonly used approaches such as pharmacokinetic matching to adults. This study systematically evaluated drug development practices used for pediatric dose selection of LADs approved by the U.S. Food and Drug Administration from 2002 to 2020. The three study objectives were: (1) to determine the dose selection approach for the labeled pediatric dose, (2) to examine the studied pediatric dose(s), and (3) to evaluate the characteristics of the pediatric clinical programs used to support the labeled pediatric dose. A total of 187 pediatric submissions were characterized for the labeled and studied pediatric doses of LADs. The pediatric dose was predominantly labeled as a flat dose (91%) and at a single-dose level (67%) similar to adults. The majority (68.4%) of the submissions had the same labeled dose for pediatrics and adults. Independent pharmacodynamic/efficacy studies in pediatric patients commonly (64.2%) provided supportive evidence for the labeled pediatric dose. Inhalation, nasal, and injectable submissions had the highest number of clinical trials, lowest usage of an extrapolation of efficacy approach, and utilized diverse approaches in selecting the studied pediatric doses. This article highlights approaches for LAD dosing in pediatric patients and can be used to inform drug development of these products in the pediatric population.

Promoting Clinical Trial Diversity: A Highlight of Select US FDA Initiatives.

Although the population in the United States is diverse, there are disparities in healthcare outcomes in some populations, for example, based on characteristics such as race, ethnicity, sex, gender, age, socioeconomic status, and geographic location. Despite disproportionate healthcare outcomes, certain populations are frequently under-represented in clinical trials intended to support applications requesting US Food and Drug Administration (FDA) approval to market a drug or biologic. Additionally, safety and efficacy of therapeutic products may vary based on intrinsic (e.g., sex, age, race, and ethnicity) and/or extrinsic (e.g., drug interactions and medical practice) factors. Enrolling diverse populations in clinical trials can aid in addressing disparities and better inform the use of medical products in all patients who will use them upon approval. Herein, we outline a few initiatives and activities, such as policy development, regulatory review, regulatory research, and stakeholder engagement, that the FDA has undertaken to promote diversity in clinical trials, to support submission of such information in marketing applications for subgroup analyses, and to communicate information to the public.

Predicting Food Effects on Oral Extended-Release Drug Products: A Retrospective Evaluation.

Theoretically, the risk of food effects for extended-release (ER) products compared to IR products may be less because: (1) postprandial physiological changes are usually transient and last for 2-3 h only; and (2) the percentage of drug release from an ER product within the first 2-3 h post dose is usually small under both fasted and fed states. The major postprandial physiological changes that can affect oral absorption of ER drugs are delayed gastric emptying and prolonged intestinal transit. Oral absorption of ER drugs under fasted state mainly occurs in large intestine (colon and rectum) while the absorption of ER drugs under fed state occurs in both small and large intestines. We hypothesized that food effects for ER products are mainly caused by intestinal region-dependent absorption and food intake is more likely to increase rather than decrease the exposure of ER products due to a longer transit time and improved absorption in small intestine. For drugs with good absorption from large intestine, food effects on the area under the curve (AUC) of ER products are usually not expected. Our survey of oral drugs approved by the US FDA between 1998-2021 identified 136 oral ER drug products. Among the 136 ER drug products, 31, 6 and 99 products exhibited increased, decreased, and unchanged AUC under fed conditions, respectively. In general, when an ER product exhibits a fasted bioavailability (BA) relative to its corresponding immediate-release (IR) product between 80-125%, regardless the solubility or permeability of drug substances, substantial food effects on the AUC of ER product are generally not expected. If the fasted relative BA data are not available, a high in vitro permeability (i.e., Caco-2 or MDCK cell permeability comparable or higher than that of metoprolol) may inform no food effect on the AUC of an ER product of high-solubility (BCS class I and III) drug.

Need for Representation of Pediatric Patients with Obesity in Clinical Trials.

Clinical trials are an integral aspect of drug development. Tremendous progress has been made in ensuring drug products are effective and safe for use in the intended pediatric population, but there remains a paucity of information to guide drug dosages in pediatric patients with obesity. This is concerning because obesity may influence the disposition of drug products. When pediatric patients with obesity are not enrolled in clinical trials, dosing options for use in this subpopulation may be suboptimal. Reliance on physiological-based dosing strategies that are not informed by evaluation of the pharmacokinetics of the drug product could lead to under- or over-dosing with ensuing therapeutic failure or toxicity consequences. Thus, representation of pediatric patients with obesity in clinical trials is crucial to understand the benefit-risk profile of drug products in this subpopulation. It is important to acknowledge that this is a challenging endeavor, but not one that is insurmountable. Collective efforts from multiple stakeholders including drug developers and regulators to enhance diversity in clinical trials can help fill critical gaps in knowledge related to the influence of obesity on drug disposition.

Informing a Comprehensive Risk Assessment of Infant Drug Exposure From Human Milk: Application of a Physiologically Based Pharmacokinetic Lactation Model for Sotalol.

Characterization of infant drug exposure through human milk is important and underexplored. Because infant plasma concentrations are not frequently collected in clinical lactation studies, modeling and simulation approaches can integrate physiology, available milk concentrations, and pediatric data to inform exposure in breastfeeding infants. A physiologically based pharmacokinetic model was built for sotalol, a renally eliminated drug, to simulate infant drug exposure from human milk. Intravenous and oral adult models were built, optimized, and scaled to an oral pediatric model for a breastfeeding-relevant age group (<2 years). Model simulations captured the data that were put aside for verification. The resulting pediatric model was applied to predict the impacts of sex, infant body size, breastfeeding frequency, age, and maternal dose (240 and 433 mg) on drug exposure during breastfeeding. Simulations suggest a minimal effect of sex or frequency on total sotalol exposure. Infants in the 90th percentile in height and weight have predicted exposures ≈20% higher than infants of the same age in the 10th percentile due to increased milk intake. The simulated infant exposures increase throughout the first 2 weeks of life and are maintained at the highest concentrations in weeks 2-4, with a consistent decrease observed as infants age. Simulations suggest that breastfeeding infants will have plasma concentrations in the lower range observed in infants administered sotalol. With further validation on additional drugs, physiologically based pharmacokinetic modeling approaches could use lactation data to a greater extent and provide comprehensive information to support decisions regarding medication use during breastfeeding.

Misclassification and discordance of measured blood pressure from patient's true blood pressure in current clinical practice: a clinical trial simulation case study.

Treatment decisions for hypertension using sphygmomanometer based measurements and the current clinical practice paradigm do not account for the timing of blood pressure (BP) measurement. This study aimed to evaluate the clinical implications of discordance between measured and true BP, to quantify BP misclassification rate at a typical clinical visit in current clinical practice, and to propose a BP calibration system to decrease the impact of timing of BP measurement. A clinical trial simulation case study was performed using an in silico Monte Carlo Simulation approach. The time-courses of BPs with and without an antihypertensive treatment effect were simulated from a baseline BP model combined with an antihypertensive PK/PD model. Virtual subject characteristics were sampled from the FDA internal database. The baseline BP model was qualified using observed 24 h ambulatory BP monitoring (ABPM) data from 225 subjects by a visual predictive check as well as a global sensitivity analysis. First of all, our results showed that the measured cuff BP in current typical clinical practice deviated from the true values. (1) Cuff BP deviated from the true values by more than 5 mmHg in 57 % (95 % CI: 54-61 %) of patients and more than 10 mmHg in 26 % (95 % CI: 22-32 %) of patients respectively. (2) These discordances were reduced to 28 % (deviation ≥ 5 mmHg, 95 % CI: 18-40 %) and 9 % (deviation ≥ 10 mmHg, 95 % CI: 4-18%) of patients assuming perfect sphygmomanometer measurement and thus represent the contribution of ignoring the daily circadian rhythm of BP. Secondly, our results showed 23-32 % of patients were misclassified to an incorrect BP category for a casual clinical visit based on JNC 7 guideline. In addition, the accuracy of the measured cuff BP varied by time of clinic visit. Specifically, 11:00 AM to 3:00 PM was identified to be the better time frame, while times before 9:00 AM were the worst time frame. Therefore, clinic visit time may need to be adjusted accordingly. Finally, we proposed an easy BP calibration method for clinic use to adjust for time of day differences due to circadian variability in case that the desirable clinic visit time cannot be tailored for practical reasons.

Current Perspective on Residual Knowledge Gaps in the Assessment of Transporter-Mediated Drug Interactions.

Assessment of transporter-mediated drug-drug interaction (DDI) is integral to drug development. A risk-based approach leveraging in vitro, in vivo, and in silico information is used to evaluate the DDI liability of drugs and inform the instructions of use. While tremendous advances have been made in recent decades, there are knowledge gaps warranting further research. Herein, we focus on select areas to advance assessment of DDI potential for drugs as substrates, inhibitors, or inducers of certain transporters.

Clinical pharmacology information in regulatory submissions and labeling: A comparative analysis of orphan and non-orphan drugs approved by the FDA.

Clinical pharmacology is an integral discipline supporting the development, regulatory evaluation, and clinical use of drugs for the treatment of both common and rare diseases. Here, we evaluated the recommendations and information available from select clinical pharmacology studies in the therapeutic product labeling of new molecular entities (NMEs) approved from 2017 to 2019 for both common and rare diseases. A total of 151 NMEs, including 72 orphan and 79 non-orphan drugs, were analyzed for recommendations and information available related to food-drug interaction, drug-drug interaction, renal impairment, hepatic impairment, QT assessment, and human radiolabeled mass balance studies using data collected from the original labeling and other regulatory documents. The analysis showed no statistically significant difference in the recommendations between orphan and non-orphan drugs except for renal impairment related recommendations in section 8 of the labeling. Although not significant, fewer hepatic impairment labeling recommendations were available for orphan drugs when compared with non-orphan drugs. At the time of initial approval, 79 postmarketing requirements (PMRs) and postmarketing commitments (PMCs) for 33 orphan drugs and 39 PMRs and PMCs for 19 non-orphan drugs were established; with most difference observed for drug-drug interaction, hepatic impairment, and QT assessment. Overall, although there was a trend for more labeling recommendations and fewer postmarketing studies and clinical trials for non-orphan drugs, there appeared to be no substantial differences in how these select clinical pharmacology studies are leveraged during the development and approval of orphan and non-orphan drugs.

Roadmap to 2030 for Drug Evaluation in Older Adults.

Changes that accompany older age can alter the pharmacokinetics (PK), pharmacodynamics (PD), and likelihood of adverse effects (AEs) of a drug. However, older adults, especially the oldest or those with multiple chronic health conditions, polypharmacy, or frailty, are often under-represented in clinical trials of new drugs. Deficits in the current conduct of clinical evaluation of drugs for older adults and potential steps to fill those knowledge gaps are presented in this communication. The most important step is to increase clinical trial enrollment of older adults who are representative of the target treatment population. Unnecessary eligibility criteria should be eliminated. Physical and financial barriers to participation should be removed. Incentives could be created for inclusion of older adults. Enrollment goals should be established based on intended treatment indications, prevalence of the condition, and feasibility. Relevant clinical pharmacology data need to be obtained early enough to guide dosing and reduce risk for participation of older adults. Relevant PK and PD data as well as patient-centered outcomes should be measured during trials. Trial data should be analyzed for differences in PK, PD, effectiveness, and safety arising from differences in age or from the presence of conditions common in older adults. Postmarket evaluations with real-world evidence and drug labeling updates throughout the product lifecycle reflecting new knowledge are also needed. A comprehensive plan is needed to ensure adequate evaluation of the safety and effectiveness of drugs in older adults.

Elucidating the Impact of Immunogenicity Assessment Postapproval: A Targeted Analysis of Immunogenicity Postmarketing Requirements and Commitments.

Insufficient availability of data to evaluate immunogenicity incidence or clinical impact during regulatory review could require further evaluation postapproval. Through a keyword search of all postmarketing requirements and commitments (PMRs/PMCs) associated with products with their original US Food and Drug Administration (FDA) approvals between 2009 and 2018, we identified products that had PMRs/PMCs established to address concerns or uncertainty related to immunogenicity. Of the 113 relevant products, 50% had an immunogenicity-related PMR/PMC; of these, 68% were related to developing immunogenicity assays and 48% requested an assessment of clinical impact. Fifty-five percent of the products with a fulfilled PMR/PMC had a change in the immunogenicity information in their labeling immediately following fulfillment. This work highlights that there are often unknowns associated with immunogenicity incidence and/or impact at the time of approval. Earlier regulatory discussions on immunogenicity assessments in premarket development could improve the understanding and communication of the risk/benefit profile and reduce the need for some immunogenicity PMRs/PMCs.

A Systematic Assessment of US Food and Drug Administration Dosing Recommendations For Drug Development Programs Amenable to Response-Guided Titration.

A key goal in drug development is optimized dosing for patients. Interactions between drug developers and regulatory scientists throughout development are important for the optimization of dosing and serve as a forum to discuss approaches for optimal dosing, such as precision or individualized dosing. To date, there has not been a systematic assessment of the advice provided by the US Food and Drug Administration (FDA) to drug developers from an individualized dosing perspective. Here, we reviewed FDA recommendations on dose selection for efficacy trials at end-of-phase meetings between the FDA and drug developers for 76 new molecular entities approved between 2013 and 2017 that are considered amenable for an individualized dosing method, response-guided titration. Forty FDA dosing recommendations were identified as specific to dose selection and design of the respective efficacy trials and subsequently: (i) characterized based on if they were supportive of individualized dosing and (ii) compared with dosing regimens used in efficacy trials and labeling at approval to evaluate if FDA recommendations were implemented. Of these 40 recommendations for efficacy trials, 35 (88%) were considered supportive of individualized dosing. Eighteen of these 40 recommendations (45%) were incorporated into efficacy trials and 11 (28%) were incorporated into labeling. This research suggests that early FDA-sponsor interactions can support the study of doses in efficacy trials that may lead to individualized dosing strategies in labeling.

Quantitative systems pharmacology: Landscape analysis of regulatory submissions to the US Food and Drug Administration.

Quantitative systems pharmacology (QSP) has been proposed as a scientific domain that can enable efficient and informative drug development. During the past several years, there has been a notable increase in the number of regulatory submissions that contain QSP, including Investigational New Drug Applications (INDs), New Drug Applications (NDAs), and Biologics License Applications (BLAs) to the US Food and Drug Administration. However, there has been no comprehensive characterization of the nature of these regulatory submissions regarding model details and intended applications. To address this gap, a landscape analysis of all the QSP submissions as of December 2020 was conducted. This report summarizes the (1) yearly trend of submissions, (2) proportion of submissions between INDs and NDAs/BLAs, (3) percentage distribution along the stages of drug development, (4) percentage distribution across various therapeutic areas, and (5) nature of QSP applications. In brief, QSP is increasingly applied to model and simulate both drug effectiveness and safety throughout the drug development process across disease areas.