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Pfizer Discloses Death Of Young Boy During Clinical Trial For ‘Investigational Gene Therapy’

Pfizer has paused the clinical trial of an experimental gene therapy for Duchenne muscular dystrophy after a young boy died.

The pharmaceutical giant told patient advocates in a letter released on Tuesday.

“We are deeply saddened to share that a patient participating in our Phase 2 DAYLIGHT study for Duchenne muscular dystrophy has passed away suddenly. On behalf of everyone at Pfizer, we extend our sympathies to his family, friends, and those closest to his care,” the letter read.

“We do not yet have complete information and are actively working with the trial site investigator to understand what happened. The patient received the investigational gene therapy, fordadistrogene movaparvovec, in early 2023,” it continued.

“Initial dosing for the placebo-controlled, randomized Phase 3 CIFFREO trial, which utilizes a crossover trial design, was also completed in 2023. We have decided to pause dosing associated with the crossover portion of CIFFREO, and we are working with regulators and the independent external Data Monitoring Committee as we learn more about this event. Other than this pause in dosing, trial activities are continuing as scheduled,” it continued.

The DAYLIGHT study included boys “2 years to less than 4 years of age.”

Read the full letter below:


STAT News reports:

A young boy died in a trial for Pfizer’s experimental gene therapy for Duchenne muscular dystrophy, the company told patient advocates Tuesday.

The boy was enrolled in Daylight, a trial studying the treatment in boys aged 2 or 3. The boy had received the therapy early last year, Pfizer told the advocates in a note posted online by Parent Project Muscular Dystrophy.

Pfizer said the boy died of cardiac arrest, but that it was still working to understand what happened and the exact cause.

Per Fierce Biotech:

Pfizer said in the community letter that it doesn’t yet have all the information about what happened to the boy and is currently working with the trial site investigator to learn more.

In light of the patient death, Pfizer has paused dosing associated with the crossover portion of CIFFREO. The pharma is also working with regulators and an independent external data monitoring committee as more information becomes available.

Besides the halt to CIFFREO dosing, trials will continue as scheduled. Other ongoing trials evaluating the gene therapy have already finished the dosing phase.

“The safety and well-being of the patients in our clinical trials remains our top priority, and we are committed to sharing more information with the medical and patient community as soon as we can,” Pfizer wrote in the letter. “We are also aware that many in the patient community are hopeful about the potential benefit of fordadistrogene movaparvovec for the treatment of DMD, and we will continue to collect data from our trials to evaluate its ability to address this disease.”

The DAYLIGHT study is assessing the safety and dystrophin expression of fordadistrogene movaparvovec and has a primary completion date set for the end of this year, according to

Back in October 2023, Pfizer Chief Scientific Officer and President of R&D Mikael Dolsten, M.D., Ph.D., called the investigational gene therapy “the main game in town” on a quarterly earnings call. The commentary came directly after a confirmatory trial for Sarepta Therapeutics’ DMD candidate Elevidys failed to hit the primary goal of a pivotal study.

This is a Guest Post from our friends over at 100 Percent Fed Up.

View the original article here.


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