From the Top Down: Fibrocell Studies Adults with Goal to Treat Pediatric Patients

In late January, Fibrocell Science, Inc. announced that it was granted allowance to initiate enrollment in the Phase 2 portion of its Phase 1/2 clinical trial of FCX-007 for recessive dystrophic epidermolysis bullosa (RDEB) by the U.S. Food and Drug Administration (FDA).

Fibrocell is collaborating with Intrexon Corporation for the treatment of pediatric patients with RDEB, and was granted Rare Pediatric Disease Designation in May 2015. In the early stages of the FCX-007 program, however, no children were included. Throughout 2017, Fibrocell evaluated the potential therapy in adults until enough successful data were collected to justify beginning to treat the pediatric population.

FCX-007 is being developed to target the disease with an autologous fibroblast, genetically modified by a DNA vector with the gene for a protein called type VII collagen or COL7. In September, data was released from three adult patients who had participated in the Phase 1 study and been administered the drug; encouraging safety and efficacy were reported.

“When you’re working with a gene therapy, it’s just smart to move in this way; to start with adults,” said John Maslowski, President and CEO of Fibrocell, in an exclusive interview with Rare Disease Report. “We want our patients to feel like we’re keeping them in mind when we develop programs like this, and we want the FDA to feel like we’re making good decisions in the way that we approach the pediatric population, which is our eventual target.”

The designs of the Phase 1 and Phase 2 portions of the study are very similar, Maslowski mentioned, however, the Phase 2 intends to include pediatrics. With permission from the FDA, Fibrocell is now allowed to include patients 7 years and older, which is the age of consent at the study’s primary site: Stanford University.

“We have 6 patients targeted in Phase 2, but we did enroll 1 adult, too. In rare disease, when you find patients who qualify for a trial, you want to make sure they’re included. You want to include as many patients as you can because rare disease patients are rare to come by.”

The objective for Maslowski isn’t the number of patients his company can enroll in a trial. A higher number of targets can increase the certainty that a particular drug is safe and effective, and if more patients are found, they may continue to be enrolled. The real goal, however, is always establishing baseline safety with what is being dosed, and finding early signs of efficacy. With that information, whether there is a risk-benefit ratio in children can be determined. That is what permits the FDA to clear the start of a study in pediatrics.

“There just isn’t a large number of patients available for this condition,” Maslowski continued, “but we want to collect enough to get some confidence that we see some safety going on here.”

As far as what he anticipates for the Phase 2, Maslowski says it’s hard to tell.

“You can’t predict data and you don’t want to say what you believe is going to happen, but you do have hypotheses on what you think scientifically and based on some of the information of what we saw in Phase 1. What we hope to see going forward is the continuation of, obviously, a good safety profile.”

When safety is mentioned, it doesn’t only pertain to severe adverse events (AEs), or any previously related AEs. Many patients diagnosed with RDEB are missing proteins, and any time a therapy is being developed to replace a protein, it is imperative that blood-serum levels and antibody responses are recorded.

The company is confident that, with continued wound-healing patterns and an expanded data set, the FCX-007 program will continue to progress as hypothesized.

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