Aisha Khan, PhD, MBA 

Executive Director, Clinical Research Cellular Manufacturing Program

Interdisciplinary Stem Cell, University of Miami Miller School of Medicine

The Resignation of Dr. Peter Marks: A Critical Loss for Science-Based Oversight and Regenerative Medicine

In March 2025, Dr. Peter Marks, M.D., Ph.D., officially resigned as Director of the U.S. Food and Drug Administration’s (FDA) Center for Biologics Evaluation and Research (CBER). His resignation follows nearly a decade of service as CBER’s head and over a decade of broader FDA leadership. Widely regarded as a scientific and regulatory cornerstone for the agency’s biologics programs, Dr. Marks’s departure marks the end of an era characterized by rigorous standards, innovation in biologic product oversight, and the rapid advancement of cell and gene therapies.

A Legacy of Impactful Regulatory Reform

Dr. Marks was appointed Director of CBER in 2016 and played a central role in shaping the U.S. regulatory framework for advanced therapeutics. His leadership coincided with the surge in development of regenerative medicine products, including stem cell-based therapies, tissue-engineered constructs, gene therapies, and extracellular vesicle-derived therapeutics.

One of Dr. Marks’ hallmark contributions was the successful implementation of the Regenerative Medicine Advanced Therapy (RMAT) designation, established under the 21st Century Cures Act. This designation provides eligible sponsors with increased interaction with the FDA and the possibility of accelerated approval for regenerative medicine products targeting serious or life-threatening diseases. Over 80 RMAT designations have been granted under this program, spanning indications such as spinal cord injury, heart failure, and neurodegenerative diseases, many of which involve stem cell-derived products, exosomes, or gene-edited constructs.

Accelerating Innovation: From COVID-19 Response to Gene Therapy Approvals

Among his most visible achievements, Dr. Marks played a critical leadership role in “Operation Warp Speed,” the U.S. government initiative launched during President Donald Trump’s first administration to accelerate the development, manufacturing, and distribution of COVID-19 vaccines. He was a key architect of the regulatory review framework that enabled the emergency use authorizations (EUAs) for the first mRNA-based vaccines, Pfizer-BioNTech and Moderna, within one year of the virus's emergence.

Support for Manufacturing and CMC Modernization

Dr. Marks also led critical CBER initiatives to modernize manufacturing expectations and improve regulatory clarity for novel biologics. His efforts to strengthen the Chemistry, Manufacturing, and Controls (CMC) review process for advanced therapies included issuing updated guidance documents on human cells, tissues, and cellular and tissue-based products (HCT/Ps), donor eligibility requirements, and potency testing.

In regenerative medicine, these efforts have been significant for sponsors developing therapies derived from mesenchymal stem cells (MSCs), induced pluripotent stem cells (iPSCs), and cell-free products like exosomes. Dr. Marks emphasized risk-based approaches to ensure product safety and consistency while allowing for flexibility in early-phase clinical trials. He supported engagement through INTERACT and pre-IND meetings, which became crucial venues for sponsors seeking early regulatory feedback regarding their manufacturing platforms and characterization strategies.

CBER’s Office of Tissues and Advanced Therapies (OTAT), a division under Dr. Marks’ leadership, has become the primary interface for industry and academic developers of regenerative medicine products. Dr. Marks has shepherded the FDA’s advancement in gene therapy oversight, culminating in the approval of 22 gene therapies during his tenure. These approvals have expanded treatment options for rare and life-threatening genetic conditions such as spinal muscular atrophy, hemophilia, and inherited retinal diseases. Through establishing robust review processes and long-term follow-up standards, he has helped ensure the safe clinical integration of complex, high-risk therapies.

Scientific Integrity and Resignation Context

Reports indicate that Dr. Marks’ decision to resign was influenced by concerns about political interference and the erosion of science-based decision-making at the agency. According to public statements, he cited increasing pressure to accommodate misinformation, particularly regarding vaccine development and public communication, as incompatible with his commitment to regulatory integrity.

This resignation comes at a time when the FDA is tasked with overseeing a growing portfolio of complex biologics, many of which have no clear precedents. Industry groups such as the Biotechnology Innovation Organization (BIO) have expressed concern about the potential vacuum in leadership and the importance of preserving consistency in regulatory policy, especially for developers navigating the accelerated pathways Dr. Marks helped establish.

Implications for the Regenerative Medicine Community

Dr. Marks’ departure is especially significant for the regenerative medicine sector. His leadership facilitated not only regulatory predictability but also an open-door approach to scientific discussion and innovation. For those developing advanced products such as allogeneic MSC, neural stem cell therapies, Schwann cells, or extracellular vesicle-based interventions for neurodegeneration, his support of expedited pathways and science-based dialogue enabled meaningful progress toward clinical translation.

While the FDA has reaffirmed its commitment to the regulatory framework built during Dr. Marks’ tenure, the transition raises questions about the agency’s future priorities in biologics. As the field continues to grow and diversify, sustained support for early engagement, flexible development models, and robust manufacturing standards will be critical.

Final Thoughts

Dr. Peter Marks' resignation represents the end of a transformative chapter in the FDA’s history of biologics regulation. His contributions have laid a durable foundation for the continued development of regenerative medicine, not only through formal pathways such as RMAT but also through a culture of engagement, scientific rigor, and regulatory innovation.

As we look ahead, a key question emerges in light of the evolving political landscape. Members of the current administration, including Robert F. Kennedy Jr., have voiced interest in reducing regulatory barriers for adult stem cell “treatments”, a space that has long been at the center of debate between innovation and oversight. What could this mean for developers, clinicians, and organizations like ISCT that have worked to establish global standards and advocate for quality and safety? Could we see increased access and flexibility, or might the lines between evidence-based therapy and commercial experimentation become even more blurred? The field may be entering a phase of regulatory recalibration, and it remains to be seen how these shifts will shape the trajectory of responsible regenerative medicine development.

As the industry awaits the appointment of his successor, it will be essential to continue advocating for leadership that champions both innovation and integrity in the regulation of advanced therapeutics.

References:

1.    AABB. (2025, March 31). Peter Marks resigns as CBER director. Association for the Advancement of Blood & Biotherapies. https://www.aabb.org/news-resources/news/article/2025/03/31/peter-marks-resigns-as-cber-director

2.    Fierce Pharma. (2025, March 29). Former CBER head Peter Marks blocked RFK Jr.'s vaccine safety database, splitting FDA. https://www.fiercepharma.com/pharma/former-cber-head-peter-marks-blocked-rfk-jr-vaccine-safety-database-splitting-fda-ap

3.    BioPharm International. (2025, April 1). FDA CBER director Peter Marks resigns. https://www.biopharminternational.com/view/fda-cber-director-peter-marks-resigns

4.    Berlin Institute of Health at Charité. (2025). Statement on the resignation of Dr. Peter Marks. https://www.bihealth.org/en/notices/statement-on-the-resignation-of-dr-peter-marks

5.    Associated Press. (2025, March 30). Top FDA vaccine regulator resigns over RFK Jr. administration’s misinformation. https://apnews.com/article/7743be11cec4e4e22c50c2ddbcb6bcd8

6.    CNN. (2025, March 28). FDA’s top vaccine regulator resigns, citing political interference. https://www.cnn.com/2025/03/28/health/fda-vaccine-peter-marks-resigns/index.html

7.    FDA. (2023, October 20). Regenerative Medicine Advanced Therapy (RMAT) designation. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/regenerative-medicine-advanced-therapy-designation

8.    FDA. (2024, January 25). Approved Cellular and Gene Therapy Products. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/approved-cellular-and-gene-therapy-products