Animal model or human cells: efficacy evidence for approved gene therapies

“Intravesical administration of rAd-IFN with the excipient Syn3 was evaluated in an orthotopic mouse model of human bladder cancer . Anti-tumor activity was observed following intravesical administration of rAd-IFN/Syn3 at 1x1010 viral particles/mouse (rAd-IFN concentration of 1x1011 vp/ml in 1 mg/mL Syn3).”

“The mice were immunocompromised which does not represent the clinical situation reliably, however this is inherent to the use of human bladder cancers cells for the xenograft.”

“Mice with a hemophilia B phenotype that were administered BEQVEZ at the recommended clinical dose level expressed the hFIX-R338L transgene in the liver and exhibited hemostatic FIX activity, supporting the expected activity and mechanism of action of the product.”

“The pharmacology studies of ELEVIDYS were conducted in rodent models of DMD including mdx mice and Dmdmdx rats.”

“The minimum effective dose level of 5.0x1012 vg/kg was identified in the definitive pharmacology study conducted in mice based on survival, brain glycosaminoglycan (GAG) concentration, Morris water maze performance, reduced brain glial fibrillary acidic protein (GFAP) , and improved neuropathology.”

“In vivo pharmacology studies conducted in 2-week-old glucose-6-phosphatase, catalytic subunit 1 (G6PC) demonstrated that IV administration of DTX401 at dose levels of 5.0 × 1011 or 1.0 × 1013 gc/kg led to dose-dependent increases in hepatic G6Pase activity and fasting glucose levels.”

“model is associated with high early mortality at weaning and mimics features of human GSDIa including hypoglycemia, growth retardation, hepatomegaly, and nephromegaly”

“Overall, the applicant showed relevant pharmacodynamic activity of AMT-010 and AMT-011 in LPL-/- mice and/or cats.”

“However, LPL-/- mice do not develop acute pancreatitis, which is the most severe complication observed in humans suffering from LPLD.”

“At 4 weeks following intravenous (IV) administration of 5x1011 to 2.3x1014 gc/kg of AMT-060 in the B6.129P2-F9tm1Dws mouse model of Hemophilia B, dose-dependent increases in vector transduction in the liver, plasma hFIX protein levels, and plasma hFIX activity were observed.”

“From the pharmacokinetic point of view, non-human primates were the most relevant species for nonclinical efficacy and safety studies, as natural hosts for AAVs.”

“Intratumoral administration of a single dose and 3 doses of talimogene laherparepvec produced statistically significant (p<0.0001) anti-tumour effect in the mouse syngeneic melanoma model (Figure 4).”

“A mouse surrogate HSV-1 vector encoding the murine GM-CSF (OncoVEXmGM-CSF; JS1/34.5-/47-/mGM-CSF) was developed and used for the in vivo mouse studies because of the inability of human GM-CSF to bind to mouse GM-CSF receptor.”

“In a piglet model of SMA, scAAV9.CBA.SMN administered by the IT ROA prevented the development of hindlimb muscle weakness and slowed overall disease progression.”

“All the submitted studies / publications have already been evaluated during marketing authorisation application for Zolgensma and are addressed below.”

“Successful engraftment of the Chim-CD18-WPRE LV transduced Lin- cells was demonstrated in recipient CD18HYP or CD18KO mice with enhanced neutrophil extravasation to tissue-specific sites of inflammation.”

“The final clinical product and source material was not used in the nonclinical studies summarized in this memo due to feasibility issues obtaining sufficient CD34+ HSCs from LAD-I patients.”

“Improvement in motor conduction abnormalities, motor coordination by rotarod testing, and neuropathology were observed compared to mice receiving GFP LVV-transduced mHSPCs when evaluated between 4-12 months post-transplantation.”

“The applicant has used the As2-/- mouse as a disease model for MLD in children. The applicant stated that neuropathological changes and symptoms observed in these mice are comparable to those patients, although symptoms are milder and disease is not life-threatening (i.e. normal life span).”

“Subretinal delivery (bilateral, simultaneous administration) of AAV2-hRPE65v2 vector (8.25 x 1010 vg/dog eye) into RPE65 mutant dogs resulted in improved pupillary responses, ERGs, and visual behavior, and reduced nystagmus.”

“Briard dogs have a naturally occurring mutation (four base-pair deletion) in canine RPE65 that results in absence of RPE65 protein expression and these dogs have been subject to study over decades”

“In vivo POC studies were also conducted using transgenic mouse models of SCD, where murine bone marrow cells (mBMCs) were transduced with the βA-T87Q LVV, a related vector encoding the same transgene, and showed expression of βA-T87Q and correction of the sickling phenotype through 3 months post-transplantation.”

“Nonclinical pharmacology studies were conducted in Otof-Q828X hom (homozygous) mice, a model of OTOF-related deafness that recapitulates the human phenotype with profound hearing loss and absent auditory brainstem responses (ABRs).”

“Nonclinical pharmacology studies were conducted in Otof-Q828X hom (homozygous) mice, a model of OTOF-related deafness that recapitulates the human phenotype with profound hearing loss and absent auditory brainstem responses (ABRs).”

“In mice administered 1.0E14 vg/kg BMN 270, blood loss and bleeding time was almost corrected to wild-type levels, comparable to the correction achieved with Xyntha® treatment.”

“The applicant specified that the study was conducted in CD1 mice, a immunocompetent mice, thus able to mount an antibody response against a heterologous human protein. Results indicated that animals with higher anti-hFVIII TAb titers had FVIII activity that was BLQ.”

“the in vivo studies in wild-type BALB/c mice and the hypomorphic DEB mouse model provided evidence that KB103 can transduce dermal cells and increase expression of COL7 protein, which is able to form anchoring fibrils.”

“In vivo pharmacology studies conducted using surrogate lineage negative (Lin-) BM cells transduced with WAS LVV transplanted into WAS-deficient mice demonstrated increased B cell, platelet, and granulocyte cell counts and improved T cell, B cell and DC function.”

“The impossibility of using autologous human cells in animal models limits the scope of possible nonclinical studies.”

“At dose levels of 1.2 x 1013 up to 1.1 x 1014 vg/kg, the single IV administration of the various clinical vector lots of AVXS-101 resulted in a dose-dependent improvement in survival in neonatal SMNdelta7 mice.”

“were evaluated in of pivotal pharmacology studies in the β-thalassaemic murine animal model. Results showed that treatment of thalassaemic mice resulted in the correction of the β-thalassaemic phenotype.”

“Considering the nature of the final drug product (human autologous thalassaemic CD34+ haematopoietic stem cells transduced with the BB305 lentiviral vector), the test articles used during non-clinical studies were surrogates”

“At 16 weeks post-administration, engrafted cells in NSG mice demonstrated >90% on-target editing frequencies in whole blood, bone marrow, and spleen.”

“No in vivo proof-of-concept studies were conducted as no relevant animal disease model for TDT and SCD exists that could be used for evaluation of exa-cel.”

“In a second study of healthy wildtype animals (C57BL/6 mice), T cells were isolated on Day 14 and 21 from mice immunized via SC injection with either PRGN-2012, GC46.empty vector, or FFB on Day 0.”

“In vivo assessment of Lenti-D-transduced healthy donor derived CD34+ HSCs transplanted in myeloablated immunodeficient mice demonstrated bone marrow and brain engraftment that was associated with stable ABCD1 transgene expression and ALDP production for the 3-month study duration.”

“There are no known animal models of CALD that recapitulate the human disease. Murine ABCD1/ALDP knockout mice (ALD mice) lack ALDP and have altered VLCFA metabolism, but the disease phenotype resembles AMN rather than ALD and does not display the cerebral inflammation and cerebral demyelination observed in human cerebral ALD (CALD).”

“In vivo: Immunodeficient mice were implanted with human hematolymphoid tissues (SCID-hu mice), irradiated and transplanted with a single dose of cultured/transduced CD34+ cells. The transduced CD34+ cells engrafted in mice, produced vector-marked and transgene expressing T and B cells and maintained in vivo lymphoid reconstitution capacity.”

“Because ethical restrictions of harvesting of human bone marrow for experimental purposes limit in vivo studies of the human hematolymphoid system, substitute human to small animal xenotransplantation models has been employed.”

“Nonclinical products were then implanted into excisional wounds generated in mice. RVV-transduced keratinocytes remained localized within explanted nonclinical products, and RVV-mediated expression of Col7 was detected for up to 12-months post-implantation.”

“In vivo pharmacology studies were conducted with a murine surrogate product, mRP1 (identical to TUDRIQEV, except that human GM-CSF is replaced by murine GM-CSF) using syngeneic murine lymphoma, colorectal and melanoma tumor-bearing immunocompetent BALB/c or C57BL/6 mice.”

“The nonclinical pharmacology program for eladocagene exuparvovec consists of in vitro studies in human cells to characterize the expression and biological activity of eladocagene exuparvovec.”

“Subsequent to the applicant commencing clinical studies, Lee et al., generated a mouse model of AADC deficiency (Lee et al., 2013, 2014).”