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November 25, 2025

Transforming rare disease drug development with Virtual Twin® QSP modeling

Drug development for rare diseases presents a unique set of challenges, from limited patient populations to high disease heterogeneity and difficulty interpreting clinical data using traditional approaches. These challenges make it hard for researchers and regulators to fully understand drug efficacy and disease progression.

To address these barriers, scientists are increasingly turning to Quantitative Systems Pharmacology (QSP), a powerful framework that integrates mechanistic biology, pharmacology, and patient-level variability to simulate how a drug interacts with disease pathways.

In this blog, we discuss Certara’s application of QSP with Virtual Twin® QSP modeling, a groundbreaking approach that brings clinical insights to life.

What is a Virtual Twin approach?

A Virtual Twin approach is a model-based, data-driven representation of an individual patient’s biological and clinical profile. Using QSP principles, a Virtual Twin model simulates how a specific patient might respond to a treatment by incorporating real-world data such as biomarkers, demographics, and disease progression patterns.

Unlike traditional data-driven “black-box” modeling, Virtual Twin modeling provides a mechanistic, transparent view of how therapies or disease progression impact biology, enabling researchers to predict outcomes and refine treatment strategies with precision.

Regulatory recognition of QSP and Virtual Twin QSP models

Global health authorities, including the FDA and EMA, have recognized the value of QSP in supporting model-informed drug development (MIDD). These mechanistic models help strengthen the biological rationale behind clinical trial designs, support dose selection, and inform regulatory submissions, particularly where patient data are limited. These advanced modeling capabilities are powered by Certara IQ™, an AI-assisted QSP modeling software that enables scientists to build, simulate, and share complex QSP and Virtual Twin QSP models with confidence.

Case study 1: Bridging adult and pediatric populations in ASMD

In the development of Olipudase alfa (Xenpozyme™) for acid sphingomyelinase deficiency (ASMD), a Virtual Twin modeling approach was used to explore disease similarity between adult and pediatric patients.

By calibrating QSP models with individual patient data, researchers created Virtual Twin models for both adult and pediatric populations. The simulations demonstrated comparable disease mechanisms and treatment responses across age groups, providing key mechanistic evidence to support partial pediatric extrapolation.

The FDA noted that the submitted QSP model offered valuable insights into ASMD progression and response to Olipudase alfa, ultimately contributing to pediatric approval alongside clinical data.

Case study 2: Tackling disease heterogeneity in Pompe disease

Another example comes from Avalglucosidase alfa (Nexviazyme™) for Pompe disease, a rare lysosomal storage disorder caused by a deficiency of the GAA enzyme.

Sanofi and Certara developed a Pompe QSP model to simulate the disease pathway across different patient groups. Virtual Twin QSP models were generated for both infantile-onset (IOPD) and late-onset (LOPD) Pompe disease patients by adjusting parameters such as residual enzyme activity.

These virtual patients allowed researchers to test and compare treatment responses under different dosing regimens, helping to overcome sample size limitations and disease heterogeneity in clinical development.

The Virtual Twin QSP modeling approach demonstrated how mechanistic modeling can augment clinical evidence, enable better decision-making, and support the use of model-based insights in rare disease programs.

The future of Virtual Twin QSP modeling in rare diseases

Virtual Twin technology represents a major step forward for model-informed precision medicine. For rare diseases, where every patient counts, Virtual Twin modeling can simulate thousands of personalized outcomes, de-risking clinical trials and accelerating access to therapies. Driving this innovation is Certara IQ, Certara’s QSP modeling software. It empowers teams to translate biological mechanisms into actionable clinical insights, advancing the next generation of Virtual Twin QSP applications

As regulatory agencies continue to embrace model-informed approaches, Virtual Twin modeling is poised to become a cornerstone of modern drug development, bridging the gap between clinical data and patient biology.

Jessica Sinha

Associate Director, Marketing – QSP, Certara

Jessica Sinha is an accomplished marketing leader with more than eight years of experience spanning B2B, brand, content, and digital marketing in the life sciences sector. At Certara, she leads strategic marketing initiatives for Quantitative Systems Pharmacology (QSP), combining her scientific foundation in bioengineering with a passion for clear, impactful communication.

FAQs

What is a Virtual Twin QSP model and how does it work?

A Virtual Twin QSP model is a data-driven, mechanistic simulation of an individual patient’s biology and disease state. Using Quantitative Systems Pharmacology (QSP), it integrates real-world clinical data, such as biomarkers, demographics, and treatment response, to predict how a patient may respond to therapy. This approach supports precision medicine by bridging patient variability and clinical decision-making.

How does Virtual Twin QSP modeling support rare disease drug development?

In rare disease drug development, patient populations are small and highly heterogeneous. Virtual Twin QSP models simulate thousands of “virtual patients” to explore disease progression, optimize dosing, and reduce clinical uncertainty. This approach helps researchers generate insights that guide trial design and regulatory decisions even with limited data.

Why are regulatory agencies interested in Virtual Twin QSP modeling?

Regulators such as the FDA and EMA recognize model-informed drug development (MIDD) as a valuable approach for rare and complex diseases. Virtual Twin QSP models offer mechanistic evidence that supports dose selection, trial design, and partial extrapolation between populations, helping build confidence in clinical and regulatory decision-making.

Learn more about Certara IQ

Certara IQ is the AI-enabled QSP modeling tool that will transform your research and scale your molecule’s potential.

Certara IQ offers flexible and scalable licensing options to cater to a variety of users and organization sizes.

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