Which risks did regulators probe for approved gene therapies?

“Development of neutralizing antibodies to the adenovirus and anti-IFNα2b antibodies occurred in the majority of animals in the high dose group and to a lesser extent in the low dose group”

“Biodistribution analysis indicated the presence of rAd-IFN DNA in the bladder on Days 8 and 98.”

“The levels of both anti-hFIX and anti-AAV antibodies increased with time, which correlated with a decline in plasma hFIX protein levels.”

“The highest vector DNA concentrations were detected in the liver, spleen, and inguinal lymph nodes.”

“The study results were uninterpretable since the positive control group of R848 CD34+ cells did not show high levels of expression of IFIT1, TIG1, OAS1, and IL-6 transcripts, which were observed in R848 PBMC cohort.”

“Human DNA was detected in most of the examined tissues in mice that received a single IV administration of 1 x 106 cells/mouse, with the highest levels detected in the bone marrow, followed by spleen, blood, lung, liver, and kidney.”

“increased antibody titers against AAVrh74 vector capsid from Weeks 5 to 12, increased cellular immune response against AAVrh74 vector capsid and micro-dystrophin at Week 2 compared to baseline”

“Systemic ELEVIDYS distribution was observed, with the highest vector levels in the liver, followed by the adrenal gland, aorta, heart, muscle, and esophagus.”

“Vector immunogenicity was greater against the AAV9 capsid versus the hSGSH transgene and was proportional to vector dose level.”

“Vector BD in brain was less than that of liver (highest) across dosed groups.”

“T-cell responses to the AAV8 peptide pool were observed in 2/10 mice on Day 29 and in 6/10 mice on Day 92.”

“DTX401 biodistribution (BD) was highest in the liver and vector DNA was detected in all evaluated tissues, including the ovaries and testes”

“on readministration, the second dose was not able to elicit a response, an effect attributable to formation of neutralising antibodies to AAV1 capsid.”

“The main tissues where vector DNA was detected were the injected muscle, liver, spleen and inguinal lymph nodes.”

“Antigenicity endpoints were included in single dose toxicity studies, capsid antigens generally caused high titres of anti AAV5 antibodies. In addition, anti-human FIX antibodies were observed inconsistently in NHP.”

“Vector DNA was also identified in the adrenal glands and spinal cord, followed by limited vector presence in various tissue types.”

“Lethal systemic viral infection was observed in up to 20% of nude mice (primarily deficient in T lymphocyte function) and 100% of SCID mice (devoid of both T and B lymphocytes).”

“Viral DNA was detected at low levels in the injection site, blood and urine at 24 hours following the administration of the 5th injection of the product.”

“Anti-AAV9 antibody responses were consistent and robust across all studies, with all participants developing high titers that remained elevated through study completion.”

“Biodistribution (BD) of OAV101 demonstrated the highest titers in the liver, DRG, and spinal cord, with lower levels reported in the periphery, including gonads.”

“The formation of anti-drug antibodies against the AAV2 vector capsid was dose dependent with the highest incidence observed in Group 4 high-dose animals at Days 30 and 180.”

“Persistence of vector DNA was most notable in the putamen, cerebrum, cerebellum, and spinal cord at all time points, with the highest levels in the putamen.”

“No development of anti-ARSA antibodies or adverse neurobehavioral effects were observed in As2-/- mice transplanted with ARSA LVV-transduced mHSPCs.”

“In addition to the bone marrow, spleen, thymus, and liver, transduced human cells were also detected at lower levels in the mouse brain, demonstrating migration of the transduced cells into target organs.”

“There were no pro-inflammatory T cell responses (IFN-γ) to the AAV2 capsid, except for one NHP previously exposed to AAV2 vector that developed a CD4+ T cell response.”

“The highest levels of vector DNA were detected primarily in the intraocular fluids (anterior chamber fluid and vitreous) of vector-injected eyes.”

“There were no serum or CSF samples positive for anti-otoferlin antibodies at any time point.”

“Viral shedding was detected in multiple samples (buccal swabs, nasal swabs, feces, and urine) on Day 2 post-administration in monkeys but was absent by 7 weeks, indicating clearance from excretory pathways.”

“The only protein sequences with alignment to the PRGN-2012 fusion antigen were proteins expressed by HPV, indicating there is a low potential for off-target human protein reactivity.”

“Shedding analyses were not required for nonclinical studies for this product as mice are generally an unreliable species for adenoviral shedding studies to compare to human shedding.”

“These anti-hFVIII antibodies cross-reacted with the murine endogenous FVIII, leading to a loss of endogenous FVIII activity, a bleeding phenotype, and subsequent visceral lesions (in heart, lungs and epididymis) associated with haemorrhages.”

“Following IV administration of 2.13 × 1014 vg/kg ROCTAVIAN, the highest vector DNA concentration was detected in the liver, followed by the lung, heart, lymph nodes, kidney, spleen, bone marrow, testis, and brain through 6 months post-administration.”

“showed increased expression of genes associated with immune cell infiltration and inflammation in injected tumors compared to non-injected tumors”

“viral genomes were predominantly present at the injection sites (i.e., tumor), irrespective of the route of administration.”

“microscopic findings of minimal to slight lymphocyte follicular hyperplasia in the spleen and minimal to slight lymphocyte hyperplasia in the axillary and/or inguinal lymph nodes were consistent with an inflammatory response to KB103”

“resulted in vector detection primarily at the injection site, which declined to baseline by 30 days after the last dose.”

“No anti-WASP antibodies have been detected in any of the 27 participants treated with WASKYRA”

“No human or LVV sequences were detected in non-hematopoietic tissues (brain and testes)”

“In the Phase 1/2a study, circulating anti-Col7 antibodies were detected in two out of seven subjects, which resolved without intervention by 1 year after treatment.”

“COL7A1 transgene DNA was detected in explanted nonclinical products at both sacrifice time points.”

“Nevertheless, the NHP raised an antibody titre against both the vector and the transgene, while the mice raised an antibody titre against the vector alone.”

“The biodistribution (BD) and SMN transgene expression profile of AVXS-101 were evaluated in neonatal FVB mice through 12 weeks.”

“No immunotoxicity studies have been performed since immunogenicity with βA-T87Q-globin is not anticipated.”

“Cell distribution was assessed by the applicant in the target tissues, BM, and peripheral blood, by VCN measurements.”

“Hematopoietic reconstitution was observed in the peripheral blood (PB) and BM and measurable VCN was detected in other hematopoietic organs, whereas undetectable or low VCN was observed in non-hematopoietic organs including the gonads.”

“Cell distribution was assessed by the applicant in the target tissues, BM, and peripheral blood, by VCN measurements.”

“the highest concentration (copies/µg) was observed in bone-marrow were signals above the upper LoQ were observed.”

“Biodistribution analysis did not show any evidence of transduction of non-target cells: vector DNA was only detected in the presence of donor cells.”