Dual Designations Affirm Significant Unmet Need; Multi-Year Phase 1 Data Published in the New England Journal of Medicine Underpin Advancement to Phase 2

ATLANTA, April 29, 2026 /PRNewswire/ — Expression Therapeutics, Inc., a clinical-stage biopharmaceutical company developing a curative autologous stem cell therapy for hemophilia A, today announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation and Rare Pediatric Disease Designation to its investigational therapy. The dual designations recognize the severity and unmet medical need of hemophilia A — a condition affecting approximately 1 in 5,000 male births in which nearly half of patients have the severe form and face a lifetime of prophylactic infusions and injections — and are designed to facilitate efficient development and pathway toward potential approval of Expression Therapeutics’ stem cell therapy.

Expression Therapeutics is collaborating with a world-class team at Stanford University to advance its program. “As leaders in hemophilia and cutting-edge treatment strategies for blood and immune diseases, including gene and cellular therapies, we are excited to see this innovative approach using autologous hematopoietic stem cell-based gene therapy in hemophilia A,” said Glaivy Batsuli, M.D., Pediatric Hematologist/Bleeding Disorder Physician and Director of Hematology Research at Stanford University.

Expression Therapeutics will also work closely with the Stanford stem cell and gene therapy team for its Phase 2 clinical trial. “We look forward to continuing to work with the Expression Therapeutics team as they advance this important program,” said Agnieszka Czechowicz, M.D., Ph.D., Pediatric Stem Cell Transplant Physician-Scientist in Stem Cell Biology, and Tami John, M.D., Bass Center Director of Clinical Gene Therapies, both of Stanford University.

As previously reported in the New England Journal of Medicine (N Engl J Med 2025;392:450–457), multi-year Phase 1 data from treated patients demonstrated sustained Factor VIII expression and complete elimination of prophylaxis, supporting the potential for long-term disease control following a single administration of the therapy. The data are particularly compelling against the backdrop of today’s standard of care: patients with severe hemophilia A currently face prophylactic regimens requiring constant infusions and/or injections at an estimated annual treatment cost of $650,000-$760,000 — a burden that persists through every year of life. These regimens offer very limited durability of Factor VIII activity, come with their own risks, and do not offer the quality of life that comes from living without hemophilia A.

Krista McKerracher, a member of Expression Therapeutics’ Board of Directors and former VP & Global Franchise Head, Oncology Global Development at Novartis, said: “These dual FDA designations represent meaningful external validation — both of the scientific approach and of the profound unmet need this therapy is designed to address. From the Board’s perspective, Expression Therapeutics is uniquely positioned to advance a differentiated, potentially durable treatment for hemophilia A, supported by compelling early clinical data and a well-defined regulatory pathway — one we believe can deliver real value for patients and stakeholders alike.”

“At Expression, we are working toward the day when a child diagnosed with hemophilia A is offered a single treatment — made in the United States — that provides unprecedented durability and genuine freedom from the burden of lifelong infusions,” said David F. Townson, Ph.D., Chief Executive Officer of Expression Therapeutics. “Reducing the annual bleed rate is not the finish line. Patients deserve a therapy that addresses the physical, psychological, and financial weight of this disease for life. That is what we are building.”

ABOUT EXPRESSION THERAPEUTICS
Expression Therapeutics, Inc., based in Atlanta, Georgia, is a clinical-stage biotechnology company advancing an investigational autologous stem cell therapy for hemophilia A and investigational cell therapies for neuroendocrine tumors (NETs) and neuroblastoma. The company’s therapies are manufactured at its U.S.-based GMP facility in Cincinnati, Ohio. For more information, visit www.expressiontherapeutics.com.

MEDIA CONTACT
Kim Nearing
Chief Business Officer
Expression Therapeutics, Inc.
1860 Montreal Road, Tucker, Georgia 30084
knearing@expressiontherapeutics.com
+1 650.743.4993

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SOURCE Expression Therapeutics, Inc.