Karen Midthun, M.D. & John Taylor to Lead Team of Experts

WASHINGTON, D.C. – Greenleaf Health, Inc., a leading Food and Drug Administration (FDA) regulatory consulting firm, today announces that the firm has expanded its portfolio of services to guide companies developing cell and gene therapy products. Greenleaf’s team of regulatory experts will be led by Karen Midthun, M.D., former Director of the FDA’s Center for Biologics Evaluation and Research (CBER), and John Taylor, former FDA Counselor to the Commissioner and Principal Deputy Commissioner.


The rapidly evolving fields of cell and gene therapy offer the possibility of novel treatments, and perhaps ultimately cures, for devastating and intractable illnesses. In response to what the FDA has called a “turning point in the development of these technologies and their application to human health,” new policies have been introduced to address the development of safe and effective cell and gene therapies.

With innovation often comes uncertainty. In the case of cell and gene therapy products, the FDA has raised concerns about developers operating outside of the existing regulatory paradigm. To prevent this, the FDA has clarified the regulatory framework for regenerative medicine products and announced near-term enforcement actions aimed at ensuring compliance by companies developing and manufacturing cell and gene therapies.

Greenleaf’s expanded services support companies striving to introduce cell and gene therapy products to patients. The firm’s team of experts has a robust blend of technical skill and FDA institutional knowledge that spans all therapeutic areas and quality, manufacturing, and compliance systems. By working cross-functionally, Greenleaf ensures that clients have the comprehensive, specialized support needed to understand and navigate the complex regulatory landscape for cell and gene therapies.


Members of Greenleaf’s Drug and Biological Products Team work together with the firm’s Product Quality, Manufacturing, and Compliance Team to deliver guidance on cell and gene therapy products.

Product Development & Review

With the expert direction of Karen Midthun, M.D., Greenleaf’s team of advisors assists sponsors of cell and gene therapies by optimizing FDA interactions and submissions to support development and regulatory review. Greenleaf also helps sponsors understand and respond to the FDA requirements applicable to various cellular products, and provides guidance to sponsors of cell and gene therapies to treat rare and ultra-rare diseases on ways to maximize trial design using appropriate clinical endpoints and natural history study data to aid efficient product development.

Quality, Manufacturing & Compliance

Greenleaf’s Product Quality, Manufacturing, and Compliance Team, led by John Taylor and supported by the firm’s network of independent compliance experts, offers credible, informed guidance to help manufacturers of cell and gene therapies comply with the FDA’s multiple current GXP regulations. Greenleaf experts provide strategic and technical support for establishing manufacturing and quality controls; pre- and postapproval inspection readiness; compliance assessments; evaluating and responding to FDA regulatory correspondence; and engaging with CBER’s Advanced Technologies Team.


Greenleaf is comprised of experts with a combined total of more than 250 years of FDA experience. The firm’s team of advisors demonstrates unmatched levels of skill in its specialties of drug and biological products and product quality, manufacturing, and compliance. Greenleaf’s Cell and Gene Therapy Team, led by Dr. Karen Midthun and John Taylor, is guided by decades of regulatory experience in senior FDA positions, global public health organizations, academia, and industry.

Karen Midthun, M.D., Principal, Drug & Biological Products

Dr. Midthun contributes specialized insight — informed by her regulatory, research, and clinical experience — to FDA-regulated entities developing cell and gene therapies. Dr. Midthun joined Greenleaf following a distinguished 28-year career in public health, of which 22 years were dedicated to the FDA.

An infectious disease physician by training, Dr. Midthun most recently served as the Director of the FDA’s Center for Biologics Evaluation and Research (CBER). During her FDA tenure, Dr. Midthun played a critical role in facilitating policy and technology development in the areas of cell, tissue, and gene therapies, blood products, and vaccines.

John Taylor, J.D., President, Greenleaf Health, and Principal, Compliance & Regulatory Affairs

Taylor has held many high-profile positions at the FDA, as well as senior leadership roles within industry. Taylor’s wealth of regulatory experience, robust technical skills, and unique strategic perspective are unmatched. Clients working with Greenleaf’s Product Quality, Manufacturing, and Compliance Team benefit from Taylor’s vast FDA institutional knowledge.

Taylor joined Greenleaf following a distinguished 20-year career at the FDA, where he served in multiple leadership positions, including as the FDA’s Acting Deputy Principal Commissioner, FDA Counselor to the Commissioner, Acting Deputy Commissioner for Global Regulatory Operations and Policy, and Associate Commissioner for Regulatory Affairs.


Greenleaf Health provides strategic and technical guidance to pharmaceutical, biotechnology, and medical device companies researching, developing, and manufacturing innovative solutions to pressing global public health challenges.

The firm includes former leaders and regulatory professionals from the FDA, Capitol Hill, top global pharmaceutical and medical device companies, leading law firms, and the top U.S. biotechnology trade organization. Greenleaf’s blend of former FDA officials and industry experts provides a unique set of capabilities when advising entities regulated by the FDA.

For more information on Greenleaf’s cell and gene therapy services and Greenleaf Health, visit