1st RDEB Patient Dosed With PTR-01 Protein Replacement Therapy in Phase 2 Trial

A Phase 2 trial of PTR-01 (also known as BBP-589) as a treatment for recessive dystrophic epidermolysis bullosa (RDEB) has dosed its first patient.

The study, known as PTR-01-002 (NCT04599881), is taking place at Stanford University and Children’s Hospital Colorado. Enrollment is ongoing. Contact information can be found here.

The investigational therapy is a recombinant, or lab-made, collagen type VII protein (rC7). It is given intravenously — into the vein — to replace the missing or faulty version of C7 caused by mutations in the COL7A1 gene, which leads to RDEB.

“BBP-589 is a potentially disease-modifying rC7 replacement therapy that we hope may improve the skin manifestations as well as the systemic symptoms these patients endure,” Sanuj K. Ravindran, MD, executive chairman of Phoenix Tissue Repair, the therapy’s developer and an affiliate of BridgeBio Pharma, said in a press release.

In animal models of RDEB, PTR-01 promoted wound healing, extended survival, and promoted the formation of anchoring fibrils — structures that connect neighboring layers of tissue.

A Phase 1/2 study (NCT03752905) of PTR-01 was then started and is expected to be completed by the end of November. Early results from nine adults with RDEB showed that treatment increased the levels of C7 in the skin and was well-tolerated.

“The results observed in the Phase 1 study give us confidence in our approach, and we are excited to continue advancing this therapeutic candidate through the clinic,” Ravindran added.

The Phase 2 trial seeks to recruit six patients, ages 12 and older. Although new patients will be enrolled, priority will be given to those who satisfactorily completed the Phase 1/2 trial.

Participants will receive PTR-01 intravenously over 18 weeks, followed by 12 weeks to monitor wound healing and other efficacy measures, such as changes in wound surface area, skin integrity, itching, and pain severity.

In the first of three parts, participants will receive 3 mg/kg of PTR-01 each week for four weeks. In the second part, participants will receive the same dose every other week to a maximum of seven doses. Part three will consist of a 12-week observation period.

The investigators will perform safety assessments throughout the study, focusing on parameters such as side effects, the development of anti-PTR-01 antibodies, and infusion-associated reactions.

Patients who complete all three parts may be eligible to participate in a long-term extension study to further refine the treatment’s dosing regimen.

The U.S. Food and Drug Administration and the European Medicines Agency have granted orphan drug designation to PTR-01. The designation confers several regulatory and financial incentives, such as tax credits and a period of marketing exclusivity — seven years in the U.S. and 10 in the European Union — if the treatment is approved. The therapy was also granted fast track designation in the U.S. to speed up its development and review.