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Pfizer doses the first participant with Its gene therapy

Pfizer doses the first participant in phase 3 study for Duchenne muscular dystrophy (DMD) investigational gene therapy.

Pfizer Inc. announced that the first participant has been dosed in the Phase 3 CIFFREO study, which will evaluate the efficacy and safety of investigational gene therapy candidate PF-06939926 in boys with Duchenne muscular dystrophy (DMD). The CIFFREO trial is expected to enroll 99 ambulatory male patients, ages 4 through 7, across 55 clinical trial sites in 15 countries. The first patient was dosed at a site in Barcelona, Spain, on December 29, 2020.

CIFFREO is a Phase 3 global, multicenter, randomized, double-blind, placebo-controlled study. The study’s primary endpoint is the change from baseline in the North Star Ambulatory Assessment (NSAA) at one year. The NSAA is a 17-item test that measures gross motor function in boys with DMD. Regardless of the cohort, eligible participants are scheduled to receive the investigational gene therapy, either at the start of the study or after one year following treatment with placebo. Participants will be followed in the CIFFREO study for five years after treatment with the investigational gene therapy. Trial participants will receive commercially representative drug products manufactured at Pfizer’s state-of-the-art gene therapy manufacturing facility in Sanford, North Carolina.


Brenda Cooperstone, MD, Chief Development Officer, Rare Disease, Pfizer Global Product Development  – “The initiation of our pivotal trial, which is the first Phase 3 DMD gene therapy program to begin enrolling eligible participants, is an important milestone for the community because there are currently no approved disease-modifying treatment options available for all genetic forms of DMD. We believe our gene therapy candidate, if successful in Phase 3 and approved, has the potential to significantly improve the trajectory of DMD disease progression, and we are working with worldwide regulatory authorities to initiate this program as quickly as possible in other countries.”


PF-06939926 received Fast Track designation from the U.S. Food and Drug Administration in October 2020 (read article), as well as Orphan Drug and Rare Pediatric Disease designations in the United States in May 2017.


Silvia Avila, President, Duchenne Parent Project Spain  – “DMD is a progressive disorder, and patients and parents are waiting desperately for treatment options. The initiation of this study is an important step forward for this community, and it fuels us with hope that one day there may be treatment options for boys impacted with this devastating disease.”


DMD is an X-linked disease caused by mutations in the gene encoding dystrophin, which is needed for muscle membrane stability. Due to the lack of dystrophin, boys present with muscle degeneration that progressively worsens with age to the extent that they require wheelchair assistance when they are in their early teens, and unfortunately, usually succumb to their disease by the time they are in their late twenties. It is estimated that there are ~140,000 boys affected by DMD worldwide.



CIFFREO is a Phase 3 global, multi-center, randomized, double-blind, placebo-controlled study to assess the safety and efficacy of PF-06939926 investigational gene therapy in 99 ambulatory male participants, ages 4 through 7 years, with a genetic diagnosis of DMD who are on a stable daily regimen of glucocorticoids. The participants are negative for neutralizing antibodies against AAV9, as measured by the test done for the study as part of screening.

Eligible participants will be randomized into Cohort 1 or Cohort 2. Treatment will consist of two single intravenous infusions, one of PF-06939926 and one of placebo; approximately two thirds will be in Cohort 1 and receive PF-06939926 gene therapy at the start of the study and placebo after one year, and approximately one third will be in Cohort 2 and receive placebo at the start of the study and receive gene therapy after one year if they remain eligible. All participants will be followed in an open-label extension study for 5 years after treatment with the gene therapy. The study’s primary endpoint is a change from baseline at one year in the North Star Ambulatory Assessment (NSAA) total score. For more information, visit ciffreoduchennetrial.com.


About PF-06939926

PF-06939926 is an investigational recombinant adeno-associated virus serotype 9 (rAAV9) capsid carrying a shortened version of the human dystrophin gene (mini-dystrophin) under the control of a human muscle specific promotor. The rAAV9 capsid was chosen as the delivery vector because of its potential to target muscle tissue.


About Pfizer Rare Disease

Rare disease includes some of the most serious of all illnesses and impacts millions of patients worldwide, representing an opportunity to apply their knowledge and expertise to help make a significant impact on addressing unmet medical needs. The Pfizer focus on rare diseases builds on more than two decades of experience, a dedicated research unit focusing on rare disease, and a global portfolio of multiple medicines within several disease areas of focus, including rare hematologic, neurologic, cardiac and inherited metabolic disorders.

Pfizer Rare Disease combines pioneering science and a deep understanding of how diseases work with insights from innovative strategic collaborations with academic researchers, patients, and other companies to deliver transformative treatments and solutions. Pfizer innovates every day, leveraging its global footprint to accelerate the development and delivery of groundbreaking medicines and the hope of cures.

Click here to learn more about their Rare Disease portfolio and how Pfizer empowers patients, engage communities in their clinical development programs, and support programs that heighten disease awareness.

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