RARE Daily

Phoenix Tissue Repair Reports Positive Results from Phase 2 Trial of PTR-01 in RDEB

May 20, 2022

BridgeBio affiliate Phoenix Tissue Repair reported positive data from the phase 2 trial of PTR-01, an intravenously-administered recombinant collagen 7 (rC7) protein replacement therapy, in patients with recessive dystrophic epidermolysis bullosa at the Society for Investigative Dermatology Annual Meeting.

Photo: Sanuj Ravindran, executive chairman of Phoenix Tissue Repair

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare genetic disorder, symptomatic from birth, that is caused by mutations in the gene encoding collagen type VII (C7) and is one of the most severe forms of epidermolysis bullosa, characterized by severe and painful skin blistering, as well as extreme fragility and scarring of mucous membranes throughout the body. There is currently no known cure or effective treatment available for patients suffering from this disease.

“In patients with recessive dystrophic epidermolysis bullosa (RDEB) even minor friction or trauma can cause debilitating blistering, tearing and scarring of the skin, along with severe pain and itching. Our data shows that treatment with PTR-01 led to rapid, consistent, and durable wound healing,” said Sanuj Ravindran, executive chairman of Phoenix Tissue Repair. “We are hopeful that by addressing the root cause of this rare disease, we will be able to provide a treatment beyond daily wound care and pain management for patients in need.”

The phase 2, open-label study was designed to examine the effect of PTR-01 on wound healing as well as other endpoints, and to evaluate the long-term safety and tolerability of the drug candidate. The data shared at the 2022 SID Annual Meeting demonstrated that PTR-01 was well tolerated when given once per week for 4 weeks and then every other week for 14 weeks.

In addition, treatment with PTR-01 led to rapid, consistent, and durable wound healing as observed in reduction of wound surface area and clinician-reported assessments. Specifically, more than 80 percent of target wounds (21/26) demonstrated a 50 percent or greater reduction in wound surface area at the end of treatment (day 120) compared to baseline. Notably, this response was observed in a breadth of wound types: recurrent (86 percent) and chronic (75 percent); and a range of wound sizes: large (89 percent) and small (77 percent), as determined by at least 50 percent reduction in wound surface area compared to baseline. Clinician assessment of the same target lesions scored on a 7-pt scale compared to baseline demonstrated similar levels of efficacy and wound improvement.

By day 15 after initiating treatment, 15 of 26 wounds (58 percent) met the response criteria of ≥2-point increase on the wound-specific scale, and at day 120, 18/26 wounds (69 percent) met the response criteria. Based on these criteria, four out of six patients who enrolled (67 percent) were responders since they had ≥2-point increase on this scale in ≥50 percent of their wounds at day 120.

Patient-reported outcomes measuring pain, essential function, mood, activities of daily living and disease impact also showed marked mean and median reductions comparing end of study to baseline. Notably, all patients that completed the study reported a decrease in pain over the course of treatment with PTR-01. There was a 36 percent mean reduction in total pain from end of study compared to baseline as measured on the Instrument for Scoring Clinical Outcomes of Research for Epidermolysis Bullosa (iscorEB) patient reported subdomain scale.

Finally, systemic administration of PTR-01 resulted in rapid deposition of recombinant collagen 7 during the loading phase (first 28 days of treatment) and remained present up to 3 months after treatment.

Phoenix Tissue Repair has initiated a Phase 2 extension study.

PTR-01 has been granted Orphan Drug Designation by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency.

Author: Rare Daily Staff

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