NF2 lacking exon 11 isoform induced by antisense gene therapy is able to recover partially merlin deficiency on NF2-related Schwannomatosis iPSC-derived spheroid model

NF2-related Schwannomatosis (NF2-SWN) is an inherited autosomal dominant disorder resulting from loss-of-function mutations in the NF2 gene, for which no effective treatment is currently available. Furthermore, truncating variants in NF2 are associated with the severest phenotype compared to in-frame or missense variants. Previously, a shorter NF2 isoform with exon 11 skipped (merlin_e-11), induced through antisense morpholino oligomers (PMOs), was able to partially rescue the deleterious effect of nonsense variants located at that exon in patients primary fibroblast. To test the potential of this approach into Schwann cells, those responsible of NF2-SWN tumours, we developed an iPSC-based model carrying heterozygous and homozygous truncating variants on exon 11 of the NF2 gene and differentiated them to Schwann cells forming spheroids. After 3 days of treatment, merlin_e-11 expression was induced in NF2-deficient cell lines. Furthermore, key pathways associated with NF2-deficiency in schwannomas, such as PI3K/Akt/mTORC and YAP levels, were recovered without signs of toxicity. These results confirm that the PMO treatment induces effective skipping of exon 11 in Schwann cell spheroids, generating an hypomorphic merlin_e-11 that has the capacity to partially rescue merlin-deficiency in NF2-SWN spheroid cell model and it being a potential treatment of patients harbouring truncating variants located in exon 11.