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Zevaskyn: what flexibility did regulators accept, and why?

prademagene zamikeracel · COL7A1 (RV-modified keratinocyte sheets)
Flexibility accepted
CarcinogenicityAccepted with a conditionBeyond the letter
No carcinogenicity or tumorigenicity studies; insertional oncogenesis risk deferred to a long-term postmarketing safety study
Why: No neoplastic histology, low insertional oncogenesis risk, routine SCC screening in RDEB · Weight of evidence · Other reason
“Carcinogenicity and tumorigenicity studies of ZEVASKYN were not conducted due to absence of neoplastic features on histology, low risk of insertional oncogenesis, and frequent SCC screening recommended for all subjects with RDEB.”
✓ VerifiedFDA summary basis for approval, p. 13Source ↗
“The potential of insertional oncogenesis associated with ZEVASKYN’S integrating viral component will be evaluated through a safety PMR to conduct a long-term safety study in ZEVASKYN treated patients.”
✓ VerifiedFDA summary basis for approval, p. 18Source ↗
DARTAcceptedBeyond the letter
No developmental and reproductive toxicity studies
Why: Vector biodistribution confined to the implanted product · Pharmacology or kinetics
“Developmental and reproductive toxicity (DART) studies of ZEVASKYN were not conducted due to the BD of RVV remaining confined to representative nonclinical products.”
✓ VerifiedFDA summary basis for approval, p. 13Source ↗
OtherVerdict not stated
Toxicology and biodistribution used a representative nonclinical product (transduced cells on acellular dermal matrix) in mice for 4 or 8 weeks
“In the toxicology and biodistribution (BD) study, nonclinical products representative of ZEVASKYN comprised of human acellular dermal matrix and RVV-transduced human keratinocytes (cells alone) were implanted into excisional wounds generated in mice for 4- or 8-weeks.”
✓ VerifiedFDA summary basis for approval, p. 12Source ↗

Same question, other gene therapies

Adstiladrin

nadofaragene firadenovec · IFN-alpha2b (adenovirus, intravesical)
No carcinogenicity studies with vector or novel excipient; weight-of-evidence assessment for a non-advanced cancer indication

Beqvez

fidanacogene elaparvovec · Factor IX
Definitive 3-month monkey GLP toxicity study used a closely related predecessor vector, not the clinical product

Casgevy

exagamglogene autotemcel · BCL11A enhancer (CRISPR-Cas9, ex vivo HSC)
No in vivo proof-of-concept study; no disease model for TDT or SCD, so engraftment and editing persistence studied in NSG xenotransplant mice

Elevidys

delandistrogene moxeparvovec · Micro-dystrophin
No developmental and reproductive toxicology studies

Fayuvi

rebisufligene etisparvovec · SGSH (AAV9)
No genotoxicity or carcinogenicity/tumorigenicity studies; weight-of-evidence risk assessment instead

Genglycos

pariglasgene brecaparvovec · G6PC (AAV8)
No carcinogenicity/tumorigenicity studies; justified by low integration risk of episomal AAV8 vector and literature

Glybera

alipogene tiparvovec · LPL (AAV1)
Toxicity evaluated in a single species (wild-type mice) only

Hemgenix

etranacogene dezaparvovec · Factor IX
Several toxicology studies used predecessor vector AMT-060 (wild-type hFIX) instead of the final product

Imlygic

talimogene laherparepvec · GM-CSF (oncolytic HSV-1)
No genotoxicity studies; non-integrating HSV-1 episome

Itvisma

onasemnogene abeparvovec (intrathecal) · SMN1 (AAV9, intrathecal)
No NOAEL in the pivotal intrathecal NHP study; DRG, spinal cord, nerve and brain findings at the clinical-equivalent dose

Kebilidi

eladocagene exuparvovec · AADC
No in vivo pharmacology studies with the product; in vitro human cell data plus published literature only

Kresladi

marnetegragene autotemcel · ITGB2 (LVV, ex vivo HSC)
Clinical product not tested; surrogate murine Lin- HSPCs transduced with the clinical vector used for definitive toxicology and biodistribution

Lenmeldy

atidarsagene autotemcel · ARSA (LVV, ex vivo HSC)
No reproductive and developmental toxicity studies

Luxturna

voretigene neparvovec · RPE65
No reproductive toxicity studies; gonadal biodistribution in dogs and primates used instead

Lyfgenia

lovotibeglogene autotemcel · HBB T87Q (LVV, ex vivo HSC)
No traditional carcinogenicity studies; insertional mutagenesis assessed by in vitro immortalization assay and integration site analysis

Otarmeni

lunsotogene parvec · OTOF (AAV, intracochlear)
No genotoxicity or carcinogenicity/tumorigenicity studies; tumorigenicity risk to be assessed in a postmarketing study

Papzimeos

zopapogene imadenovec · HPV6/11 antigens (gorilla adenovirus)
Definitive repeat-dose toxicology study non-GLP, in wild-type mice only; murine antigen processing likely differs from human

Roctavian

valoctocogene roxaparvovec · Factor VIII
No carcinogenicity or tumorigenicity studies (nor safety pharmacology or DART studies)

Skysona

elivaldogene autotemcel · ABCD1 (LVV, ex vivo HSC)
Safety tested only in single-dose studies in immunodeficient myeloablated mice given healthy-donor transduced cells

Strimvelis

autologous CD34+ cells transduced with ADA (no INN) · ADA (gamma-retroviral, ex vivo HSC)
No tumorigenicity study: long-term engraftment of transduced cells in mice not achievable; risk assessed from clinical data and vector literature

Tudriqev

vusolimogene oderparepvec · GALV-GP + GM-CSF (oncolytic HSV-1)
Rat toxicology, biodistribution and DART studies used the murine surrogate mRP1 (murine GM-CSF); clinical product tested only in tumor-bearing mice

Vyjuvek

beremagene geperpavec · COL7A1 (HSV-1, topical)
Toxicity tested in a single species (mouse), chosen only on historical use

Waskyra

etuvetidigene autotemcel · WAS (LVV, ex vivo HSC)
Pharmacology and toxicology done with murine surrogate HSPCs transduced with the WAS vector in mice, not the human product

Zolgensma

onasemnogene abeparvovec · SMN1
Pivotal toxicity in neonatal mice only; no adequate safety study in a species closer to human (NHP study non-GLP, low-dose pilot)

Zynteglo

betibeglogene autotemcel · HBB T87Q (LVV, ex vivo HSC)
No carcinogenicity studies; low risk of oncogenic transformation concluded from the available vector data

Summary across all 26 gene therapies →