The staggering reality of drug development is that over 90% of promising medications fail when they reach human trials, resulting in immense financial losses, delays, and a lack of treatment options for patients. This inefficiency has long been accepted by the pharmaceutical industry, but a paradigm shift is underway. It's time to rethink the way we develop drugs and prioritize human-centric approaches.
With cutting-edge technologies, researchers are now able to test drugs directly on human biological systems, envisioning a future where drug development is more accurate, efficient, and compassionate.
Why Animal Models Fall Short
Animal testing has been a cornerstone of drug development, but its limitations are becoming increasingly apparent. Even minor differences in how various species process drugs, such as variations in metabolism or immune response, can lead to drastically different outcomes between animal studies and human trials.
Take, for instance, the cases of vupanorsen, ziritaxestat, and BMS-986094. These drugs appeared safe and effective in animal studies, but caused severe adverse reactions in humans, ultimately leading to the termination of their development. These are not isolated incidents; they highlight a persistent gap between preclinical and clinical safety assessments.
The Problem with Animal Studies
Clinical trial data analyses reveal that up to half of drug failures are due to a lack of efficacy in humans. Around 30% are attributed to unmanageable toxicity, while the remaining failures are linked to poor drug properties or commercial misalignment. Species differences and the inability of animal models to capture the complexity of human disease are at the heart of these issues.
The Promise of Human Organ Testing
One of the most promising alternatives to animal testing is the use of donated human organs that cannot be transplanted. Advances in organ perfusion technology allow researchers to maintain these organs in a living state outside the body, creating a unique platform for drug testing.
Perfused human organs offer several advantages. They provide physiological responses that are likely to be more similar to those seen in patients, including subtle metabolic and toxicological pathways that animal models often miss. Researchers can collect high-resolution data by introducing drug candidates and observing real-time responses, which is particularly valuable for capturing early warning signals before damage occurs.
How Human Organ Testing Works
When a donated organ is not suitable for transplantation, it can be redirected for research with the full consent of the donor or their family. The organ is then quickly prepared for perfusion in a laboratory setting, using the same preservation systems as those used in clinical transplantation.
Once connected to a perfusion machine, the organ is kept alive by circulating a blood-like fluid. Researchers can administer drug candidates and monitor responses through imaging, fluid biomarkers, and tissue biopsies. This process mimics human physiology while providing a level of observation and control that is impossible in living patients.
Ethical Considerations and Privacy
Ethical safeguards are crucial in human organ testing. Organs are donated voluntarily with informed consent, and data is de-identified to protect confidentiality. The ultimate goal is to ensure equity in research, reflecting the diversity of real patient populations, and developing therapies that benefit everyone. This approach also provides an opportunity to honor the wishes of donors and their families who want to contribute altruistically, even when transplantation is not an option.
Shifting Perspectives in Regulation and Industry
Regulators and industry leaders are beginning to recognize the need for change. The US Food and Drug Administration (FDA) has started phasing out certain animal testing requirements, including for monoclonal antibodies, and Congress passed the FDA Modernization Act 3.0 in 2024 to accelerate this transition. The National Institutes of Health has also committed to prioritizing human-based research technologies.
For pharmaceutical companies, integrating human organ data with other streams, such as clinical records and molecular data, can provide a more comprehensive understanding of human biology before entering costly First in Human Trials. This approach complements animal data, but places human-centric data at the forefront.
Impact on Patients
The potential impact on patients is significant. By reducing the number of failed trials, more therapies can advance to market and reach those in need faster. Each averted failure represents not only financial savings but also years of potential suffering avoided.
Looking to the Future
The future of drug development is likely to involve a convergence of technologies, including perfused human organs, organs-on-chips, 3D bioprinting, and multi-omics data streams, integrated with artificial intelligence. Machine learning's ability to unify diverse datasets holds the promise of uncovering insights into human physiology that were previously inaccessible.
For this vision to become a reality, innovators must demonstrate the reproducibility, reliability, and advantages of these technologies over traditional models through rigorous validation studies. Regulators must also provide transparent pathways for qualification and acceptance. Progress is already underway, with regulators publishing guidance and creating programs to qualify non-animal models.
The Way Forward
While animal models will likely continue to play a reduced role, human-relevant technologies are expected to become the backbone of development pipelines. This integrated approach, where the right model is chosen for the right question, has the potential to accelerate timelines, improve translational accuracy, and ultimately deliver safer and more effective therapies to patients.
The 90% failure rate in drug development is not an inevitable statistic; it's a call to action. Animal models have advanced science, but their limitations are now too costly to ignore. Human organ testing, combined with complementary technologies, offers a path to align drug development more closely with human biology.
The shift is happening, supported by regulators, driven by scientific advancements, and demanded by patients. What was once considered unthinkable is now seen as the path forward. As we move towards a future where animal reliance is gradually replaced by human-based systems, the prospect of safer, faster, and more effective therapies is within reach.
About the Authors
The authors of this article are members of Revalia Bio's leadership team, dedicated to pioneering human data trials, a new category of pre-clinical research that provides drug developers with early, predictive insights from real, functional human organs. The team includes Greg Tietjen (CEO), Jenna DiRito (COO), Kourosh Saeb-Parsy (CMO), Janet Nikolovski (Chief Data & Innovation Officer), and Nabil Boutagy (Director of Human Data Trial Operations).
