Jaguar Gene Therapy to Initiate Inaugural Pediatric Clinical Trial Targeting a Genetic Form of Autism Spectrum Disorder and Phelan-McDermid Syndrome

• The company recently conducted a Type C meeting with the U.S. Food and Drug Administration (FDA) and is cleared to proceed with dosing of pediatric patients (2+ years) with JAG201 with expansion into adults (18+ years) following the pediatric cohort
• The first gene therapy clinical trial to evaluate therapeutic impact in a genetic form of autism and Phelan-McDermid syndrome. Site initiation to begin immediately and patient enrollment anticipated in Q12025.
• There are currently no treatments for the ~46,000 individuals in the U.S. with autism due to SHANK3 haploinsufficiency and those diagnosed with Phelan-McDermid syndrome
• JAG201 has been granted Rare Pediatric Disease designation and Fast Track designation by the FDA

LAKE FOREST, Ill., July 9, 2024 – Jaguar Gene Therapy, a clinical-stage biotechnology company accelerating breakthroughs in gene therapy for patients suffering from severe genetic diseases including those that impact sizeable patient populations, today announced the receipt of U.S. Food and Drug Administration (FDA) responses from a Type C meeting regarding the Phase I clinical trial for JAG201, a gene replacement therapy that targets a genetic form of autism spectrum disorder (ASD) where a SHANK3 mutation or deletion is present, and Phelan-McDermid syndrome. Specifically, the company received the FDA’s agreement to administer JAG201 to both pediatric and adult patients. Jaguar Gene Therapy plans to dose the first pediatric patient in Q1 of 2025 with expansion into adults following the pediatric cohort.

“We are pleased to have reached agreement with the FDA to dose both pediatric and adult patients in our initial Phase I clinical trial of JAG201. Our preclinical data suggest that the administration of the gene therapy early in life provides a clear potential for benefits to be realized,” said Joe Nolan, CEO of Jaguar Gene Therapy. “Our hope is that potential early success in the pediatric population will open the door to evaluating JAG201 in broader patient populations. We look forward to continuing to work with the FDA, key opinion leaders and advocacy organizations in our efforts to bring forward a gene therapy treatment for autism spectrum disorder due to SHANK3 haploinsufficiency and genetically confirmed Phelan-McDermid syndrome.”

“I think intervening earlier in a patient’s course of illness to address the underlying deficits caused by the SHANK3 deficiency while individuals are still actively undergoing development will provide a greater potential for benefit,” said Alexander Kolevzon, M.D., Professor of Psychiatry and Pediatrics at the Icahn School of Medicine at Mount Sinai. “There is an incredibly high unmet need among people living with Phelan-McDermid syndrome, and we expect there will be many eligible patients to participate in this important clinical trial.”

JAG201 delivers a functional SHANK3 minigene via an adeno-associated virus serotype 9 (AAV9) vector to target neurons in the central nervous system. The therapy is administered via a one-time unilateral intracerebroventricular (ICV) injection, targeting the entire brain and spinal cord. JAG201 is designed to transduce haploinsufficient neurons to provide proper SHANK3 levels and to durably restore the synaptic function required for learning and memory, which underlie appropriate neurodevelopment and maintenance of cognitive, communicative, social and motor skills. The program is exclusively licensed from Broad Institute of MIT and Harvard.

Recently, the FDA granted Rare Pediatric Disease designation for JAG201. The designation is granted for products that treat serious and life-threatening rare pediatric diseases. Under this program, companies are eligible to receive a priority review voucher for a subsequent marketing application for a different product following approval of a product with Rare Pediatric Disease designation.

The FDA has also granted Fast Track designation for JAG201 based on the potential for the therapy to address a high unmet medical need for patients living with ASD where a SHANK3 mutation or deletion is present, and Phelan-McDermid syndrome. Currently, there are no therapeutic treatments approved for SHANK3 haploinsufficiency. Fast Track status allows for enhanced communication and collaboration between the FDA and drug developers, potentially accelerating the delivery of treatments to patients.

About SHANK3 haploinsufficiency in ASD and Phelan-McDermid syndrome

SHANK3 haploinsufficiency leads to synaptic dysfunction, disrupting communication between nerve cells. It causes a reduction of several key receptors and signaling proteins at excitatory synapses, resulting in impaired synaptic formation and function. Adequate synapse function is an essential prerequisite of all neuronal processing, including higher cognitive functions and learning.

SHANK3 haploinsufficiency causes Phelan-McDermid syndrome (also known as 22q13.3 deletion syndrome), a rare genetic disorder with an estimated prevalence of 1 in 10,000.1,2 Genetic sequencing studies indicate that SHANK3 mutations may be present in approximately 0.5%-0.69% of patients with ASD, equating to around 46,000 patients in the U.S., including approximately 10,000 pediatric patients under the age of 18, although diagnosed cases are perceived as low by clinical experts given the barriers of access and low adoption of genetic testing in the diagnostic journey of ASD.3,4,5,6 In the subset of ASD patients who also have moderate to profound intellectual disability (ID), the prevalence of SHANK3 mutations increases from less than 1% to 2.12%.3,7

About Jaguar Gene Therapy

Jaguar Gene Therapy, LLC is a clinical-stage biotechnology company dedicated to accelerating breakthroughs in gene therapy for patients suffering from severe genetic diseases including those that impact sizeable patient populations. The company is made up of a proven team of experts who have first-hand experience in bringing novel gene therapy treatments to patients and their families. Jaguar is rapidly advancing an initial pipeline of three programs. The company’s lead program targets severe neurodevelopmental disorders caused by SHANK3 haploinsufficiency, due to loss of function mutations or deletions in SHANK3 including a genetic form of autism spectrum disorder and Phelan-McDermid syndrome. A clinical trial in pediatric patients is planned to begin in Q1 of 2025. The second pipeline program targets Type 1 galactosemia and the third targets Type 1 diabetes. Jaguar’s key investors include Deerfield Management Company, ARCH Venture Partners and Eli Lilly and Company. For more information, please visit and follow Jaguar Gene Therapy on LinkedIn.

1. Costales JL et al. Neurotherapeutics 2015; 12 (3): 620–630.
2. What is Phelan-McDermid syndrome? Available at: Accessed January 2023.
3. Betancur C et al. Mol Autism 2013; 4 (1): 17.
4. Jaguar Gene Therapy market research, 2022; data on file.
7. Leblond CS et al. PLoS Genet 2014; 10 (9): e1004580.

Dr. Alexander Kolevzon has served as a paid consultant for Jaguar Gene Therapy.

Kate Neer
(815) 978-3891