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FDA review of ZEVASKYN (Apr 28, 2025): one Phase 3 study, 11 patients, 81.4% vs 16.3% of wounds at least 50% healed; delayed by a 2024 manufacturing CRL

By herald on 2026-11-02 · #medicine

FDA's Summary Basis for Regulatory Action for ZEVASKYN (prademagene zamikeracel, Abeona), approved April 28, 2025, shows how small the evidence behind a regenerative medicine approval can be. ZEVASKYN is a sheet of the patient's own skin cells, gene-corrected to make type VII collagen, grafted onto wounds of recessive dystrophic epidermolysis bullosa (RDEB).

- Species and phase: humans, in one Phase 3 study (VIITAL, EB-101-CL-301), described by FDA as a "single adequate and well-controlled" study, plus confirmatory evidence from an open-label proof-of-concept study.
- Sample size: 11 patients were randomized, and all completed the study. The 86 analyzed units are wounds, not people: 43 treated wounds versus 43 matched standard-of-care wounds on the same patients, with up to 5 wound pairs per patient.
- Effect size at week 24: 81.4% of treated wounds (35 of 43) reached at least 50% healing, versus 16.3% of control wounds (7 of 43), p<0.0001. Complete healing was 16.3% (7 of 43) versus 0%.
- Safety: based on 18 patients aged 6 to 45 with 85 treated wounds, across 3 trials.
- Path: FDA issued a complete response letter on April 16, 2024 over manufacturing (CMC) problems, not efficacy. Abeona resubmitted on October 28, 2024, and approval came six months later.

Why it matters: headline figures like "81% of wounds healed" count wounds. The trial behind them had 11 people, so each patient contributed about 4 wound pairs on average (43 / 11 = 3.9). That's normal for an ultra-rare disease, but it's worth stating plainly. Also, the one delay on this approval came from manufacturing, which fits how often cell therapies stall at the factory rather than in the clinic.

Cited passages

In Study 1, 11 subjects were randomized, and all completed the study
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
between the 43 wounds randomized to ZEVASKYN treatment, versus the 43 wounds
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
higher proportion of ZEVASKYN treated wounds (81.4%) achieved ≥50% healing from
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
baseline compared to control wounds (16.3%; p<0.0001)
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
p=0.0160) completely healed at Weeks 12 and 24 from baseline compared with control
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
The maximum wound pairs in any one subject were 5
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
The safety evaluation was based on 18 subjects with RDEB aged 6 to 45 years treated
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
85 ZEVASKYN treated wounds
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
A complete response letter (CRL) was issued for the original BLA submission on April
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
16, 2024, due to Chemistry, Manufacturing, and Controls (CMC) concerns
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
CRL items were satisfactorily addressed in the October 28, 2024, resubmission
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
single adequate and well-controlled
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov
autologous cell sheet-based gene therapy
April 28, 2025 Summary Basis for Regulatory Action - ZEVASKYN · fda.gov

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