Introduction: ICH M15 & FDA Latest Updates
Two recent regulatory developments from the ICH and FDA may signal a meaningful evolution in how drugs are evaluated and approved.
First, the International Council for Harmonisation (ICH) approved and adopted the M15 Guideline on General Principles for Model-Informed Drug Development (MIDD) in February 2026. This guideline formalizes the global framework for using modeling and simulation to inform drug development and regulatory decision-making. Regulatory agencies, including the FDA, are expected to implement this harmonized guidance within their respective regions.
Second, the FDA has reiterated that, under certain circumstances, a single adequate and well-controlled Phase 3 trial (supported by robust confirmatory evidence) may be sufficient to establish substantial evidence of effectiveness. That confirmatory evidence may include exposure-response modeling, prior clinical data, mechanistic understanding, or other quantitative analyses. While this flexibility from the FDA is not brand new law — FDA leadership has more recently emphasized this approach publicly.
In parallel, broader regulatory initiatives are also exploring ways to reduce reliance on traditional animal toxicology studies through alternative approaches such as modeling and human-relevant in vitro systems. As these shifts continue, the expectation is not less rigor, but a greater reliance on high-quality, translatable data generated early in development to support downstream decision-making.
Taken together, these developments reinforce a clear direction: integrated concentration data and quantitative modeling as either a PBPK or population PK model are no longer optional enhancements to early nonclinical and clinical developmentprograms—they are increasingly central to regulatory strategy to reduce toxicology testing and clinical trials.
What Is Model-Informed Drug Development (MIDD)?
Model-Informed Drug Development refers to the use of quantitative models to integrate data across nonclinical and clinical studies in order to inform decision-making. This can include physiologically based pharmacokinetic (PBPK) modeling, population PK (PopPK) modeling, exposure-response analysis, and clinical trial simulations.
The ICHs updated guidance and the FDA’s support reinforces the importance of using modeling to support dose selection, optimize trial design, justify extrapolation strategies, and strengthen regulatory submissions. Rather than viewing modeling as an exploratory or academic exercise, the Agency continues to formalize its role in regulatory evaluation.
Importantly, MIDD is not about replacing clinical data—it is about maximizing the value of the data you already have and using it to make more informed, efficient decisions.
The Shift from Two Phase 3 Trials to One
For decades, the standard expectation for most new drug applications has been two adequate and well-controlled Phase 3 trials to establish efficacy. The FDA recently communicated that, under appropriate circumstances, one confirmatory trial may be sufficient—when accompanied by strong supporting evidence.
This is not a new statutory change, but a clearer articulation of the FDA’s long-standing flexibility to rely on a single pivotal trial when supported by robust confirmatory evidence. That supporting evidence may include:
- Robust exposure-response modeling
- Well-characterized PK/PD relationships
- Consistent data across earlier-phase studies
- External data or real-world evidence
- Mechanistic understanding supported by modeling
This does not lower the evidentiary bar. Instead, it shifts the emphasis toward integrated, quantitative justification. Sponsors must demonstrate that the totality of evidence supports efficacy and safety with sufficient confidence—even if derived from fewer traditional trials.
In other words, modeling reduces regulatory risk by reducing scientific uncertainty.
What This Means for Sponsors
Sponsors who integrate MIDD early—starting in nonclinical development to understand potential toxicology exposure and scaling for first in human Phase 1 trials and continuing through Phase 2—will be better positioned to take advantage of regulatory flexibility. Waiting until Phase 3 to consider modeling strategies may limit those opportunities.
Practical implications include:
- Designing Phase 1 and Phase 2 studies with exposure-response objectives in mind
- Developing robust PopPK models early
- Conducting clinical trial simulations to optimize endpoints and sample size
- Using modeling to support dose justification discussions with the FDA
- Engaging in early regulatory dialogue around quantitative strategies
Programs that proactively build a quantitative framework may be able to reduce development time, control costs, and strengthen their submission packages.
Experience Still Matters
While the ICH M15 guideline formalizes the role of model-informed drug development, it does not diminish the need for expert judgment. Models must be biologically plausible, statistically sound, and grounded in real-world pharmacology.
Quantitative tools are powerful—but they require experience to design appropriately, challenge assumptions, and communicate results effectively in regulatory settings. As drug development continues to evolve, experience-guided modeling and integrated strategy will play an increasingly central role in bringing therapies to patients efficiently and confidently.
Conclusion
The adoption of the ICH M15 general principles for model-informed drug development, , combined with the FDA’s continued openness to accepting a single adequate and well-controlled Phase 3 trial when supported by robust confirmatory evidence, reflects an evolving regulatory environment—one that rewards integrated data, quantitative rigor, and thoughtful development strategy.
For sponsors, this represents both an opportunity and a responsibility. Those who invest early in model-informed strategies may gain flexibility, efficiency, and competitive advantage. Those who rely solely on traditional development pathways may find themselves at a disadvantage.
Contact us to learn how Xyzagen’s experience-led, model-informed approach from discovery through clinical development can help position your program for regulatory success with confidence.
