Donald Kohn’s Gene Therapy Breakthroughs Earn Medical Academy Honor

Donald Kohn, a UCLA physician-scientist whose four decades of research have helped move blood stem cell gene therapies from laboratory experiments into clinical care, has been elected to the National Academy of Medicine. The election recognizes professional achievement, service and major contributions to medical science, health care and public health. For Kohn, the honor reflects a career centered on a technical challenge that is both highly specialized and profoundly human: correcting inherited defects in the blood-forming cells that sustain the immune system, thereby giving children and other patients a chance to survive diseases once regarded as nearly untreatable.

Kohn is a distinguished professor of microbiology, immunology and molecular genetics in the UCLA College and of pediatrics and molecular and medical pharmacology in the David Geffen School of Medicine at UCLA. He is also a member of the UCLA Broad Stem Cell Research Center and the UCLA Health Jonsson Comprehensive Cancer Center. A pediatric bone marrow transplant physician as well as a gene therapy researcher, he has spent nearly 40 years developing and advancing treatments through clinical trials, with the aim of improving care, expanding treatment choices and reaching more patients. “It’s a great recognition of a lifetime of work and research,” Kohn said. “We don’t do this to get awards — we do it because we’re trying to accomplish something for our patients.”

The foundation of Kohn’s career was shaped by several influential mentors. Richard Hong, whose work treating children with severe combined immunodeficiency, drew Kohn into the field, provided his initial inspiration. R. Michael Blaese mentored him during a fellowship at the National Institutes of Health, while Robertson “Robbie” Parkman, his division chief at Children’s Hospital Los Angeles, later guided his professional development. Kohn also credited the research collaborators and clinical colleagues who worked alongside him, describing himself as the conductor in an orchestra of “virtuoso players.” He was recruited to UCLA in 2009 by stem cell and gene therapy leaders Owen Witte, Judith Gasson and James Economou, who he said helped create the interdisciplinary environment and research resources needed for his work to flourish.

One of Kohn’s most consequential contributions is his work on adenosine deaminase-deficient severe combined immunodeficiency, known as ADA-SCID. In this rare disorder, the absence of functional ADA enzyme cripples the immune system by preventing healthy immune cells from developing normally. Kohn and his colleagues treated their first patient with gene therapy in 1993 and have spent more than three decades refining an approach that adds a healthy copy of the ADA gene to a patient’s own blood-forming stem cells. Once modified, those stem cells can generate immune cells capable of restoring immune function. Long-term results published in 2025 from the largest study of the therapy to date found that immune function was restored and maintained in 59 of 62 children. Kohn and his collaborators are now working to move the treatment toward approval by the U.S. Food and Drug Administration so that it can become more widely available.

The rationale for this strategy lies partly in the limitations Kohn observed while performing bone marrow transplants. A conventional transplant can depend on finding a sufficiently well-matched donor, and donor immune cells may attack the recipient’s body, producing graft-versus-host disease. Reusing a patient’s own genetically modified stem cells avoids that donor-recipient mismatch and can require substantially less chemotherapy than a donor transplant. It may also eliminate the need for immune-suppressing medication after treatment. The approach illustrates a central principle of ex vivo gene therapy: a patient’s cells can be removed, genetically corrected in a laboratory and returned to the body to rebuild a deficient system. The technical simplicity of that overview conceals the considerable work involved in delivering genes effectively, preparing patients for therapy and demonstrating that any immune recovery will endure.

That same platform has produced another historic regulatory milestone. Kohn led UCLA’s participation in a multicenter clinical trial of a gene therapy for severe leukocyte adhesion deficiency type I, or LAD-I, a potentially fatal immune disorder that impairs the ability of white blood cells to move from the bloodstream into tissues. In March 2026, the FDA approved the therapy, called Kresladi, after all nine children enrolled in the trial survived and showed sustained restoration of immune function. Kresladi is the first FDA-approved treatment for severe LAD-I and the first gene therapy in which Kohn has been involved to secure regulatory approval. The result also demonstrates how a rare-disease trial can validate multiple parts of a treatment strategy at once: the biological mechanism, the procedure for modifying stem cells, the conditioning regimen required before reinfusion and the durability of the immune correction.

Kohn’s decade-long work on gene therapy for sickle cell disease has yielded additional insights even though the source does not describe that program as having reached approval. His research helped clarify the effects of chemotherapy conditioning, inflammation and gene delivery, knowledge that may improve future treatments for sickle cell disease and related blood disorders. These issues are central to translating a promising laboratory result into a tolerable and effective clinical treatment. Conditioning makes space for corrected cells to take residence in the bone marrow, but it can also provoke inflammation and other adverse effects. Efficient gene delivery is likewise essential for achieving a clinically meaningful level of functional protein. By examining those barriers across diseases, Kohn’s laboratory has helped refine the platform rather than treating each inherited disorder as an entirely separate scientific problem.

The broader laboratory is now extending blood stem cell gene therapy to additional conditions while investigating gene-editing technologies such as CRISPR-Cas9 and base editing. Current projects include potential treatments for alpha thalassemia major, mucopolysaccharidosis type IIIB, also known as MPS IIIB or Sanfilippo syndrome type B, Angelman syndrome and X-linked agammaglobulinemia. Conventional gene addition supplies a functional copy of a gene, whereas editing seeks to alter DNA directly, including correcting a disease-causing mutation or changing a regulatory sequence. These complementary approaches could expand the range of disorders addressable by stem cell therapy. They also raise distinct safety and delivery questions, making the long-term clinical data generated by earlier programs important for evaluating where correction, addition or precise editing offers the most benefit.

Beyond laboratory and clinical research, Kohn has held prominent leadership positions in gene and cell therapy. He has served as president of both the American Society of Gene and Cell Therapy and the Clinical Immunology Society, and as a member and chair of the National Institutes of Health Recombinant DNA Advisory Committee. His previous honors include the American Society of Gene and Cell Therapy’s outstanding achievement award, a career achievement award from the International Society for Cell and Gene Therapy, the Distinguished Clinical Scientist Award from the Doris Duke Charitable Foundation and a lifetime achievement award from the Pediatric Blood & Marrow Transplant Consortium. He has also been recognized for mentoring the next generation of physician-scientists and gene therapy researchers, extending his influence beyond his own laboratory and clinical trials. Kohn said election to the academy is not a reason for him to stop. “This is what I like doing. This is what I’m good at,” he said. “And so I plan to keep doing this, trying to bring new treatments to the clinic for patients.”

Subject of Research: Donald Kohn’s development of blood stem cell gene therapies and election to the National Academy of Medicine

Article Title: UCLA gene therapy pioneer Dr. Donald Kohn elected to National Academy of Medicine

Article References: UCLA gene therapy pioneer Dr. Donald Kohn elected to National Academy of Medicine. Original publication (Bibliographic details unavailable.)

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Keywords: Donald Kohn, gene therapy, blood stem cells, ADA-SCID, severe LAD-I, Kresladi, sickle cell disease, CRISPR-Cas9, base editing, UCLA, National Academy of Medicine, rare immune disorders