2'-O-methoxyethyl splice-switching oligos correct splicing from IVS2-745 b-thalassemia patient cells restoring hemoglobin A production and chain rebalance

Alisa Dong, Valentina Ghiaccio, Irene Motta, Shuling Guo, Raechel Peralta, Susan M. Freier, Andy Watt, Sagar Damle, Yasuhiro Ikawa, Danuta Jarocha, Maxwell Chappell, Coralea Stephanou, Paola Delbini, Connie Chen, Soteroula Christou, Marina Kleanthous, Kim Smith-Whitley, Deepa Manwani, Carla Casu, Osheiza AbdulmalikMaria Domenica Cappellini, Stefano Rivella, Laura Breda

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


B-thalassemia is a disorder caused by altered hemoglobin protein synthesis which affects individuals worldwide. Severe forms of the disease, left untreated, can result in death before the age of 3 years.1 The standard of care consists of chronic and costly palliative treatment by blood transfusion combined with iron chelation. This dual approach suppresses anemia and reduces iron-related toxicities in patients. Allogeneic bone marrow transplant is an option, but limited by the availability of a highly compatible hematopoietic stem cell donor. While gene therapy is being explored in several trials, its use is highly limited to developed regions with centers of excellence and well-established healthcare systems.2Hence, there remains a tremendous unmet medical need to develop alternative treatment strategies for b-thalassemia.3 Occurrence of aberrant splicing is one of the processes that affects b-globin synthesis in b-thalassemia. The (C>G) IVS2-745 is a splicing mutation within intron 2 of the b-globin (HBB) gene. It leads to an aberrantly spliced mRNA that incorporates an intron fragment. This results in an in-frame premature termination codon that inhibits b-globin production. Here, we propose the use of uniform 2'-O-methoxyethyl (2'-MOE) splice switching oligos (SSO) to reverse this aberrant splicing in the pre-mRNA. With these SSO we show aberrant to wild-type splice switching. This switching leads to an increase of adult hemoglobin up to 80% in erythroid cells from patients with the IVS2-745 HBB mutation. Furthermore, we demonstrate a restoration of the balance between b-like- and α-globin chains, and up to an 87% reduction in toxic heme aggregates. While examining the potential benefit of 2'-MOE-SSO in a mixed sickle-thalassemic phenotypic setting, we found reduced sickle hemoglobin synthesis and sickle cell formation due to HbA induction. In summary, 2'-MOE-SSO are a promising therapy for forms of b-thalassemia caused by mutations leading to aberrant splicing.

Original languageEnglish (US)
Pages (from-to)1433-1442
Number of pages10
Issue number5
StatePublished - May 2021
Externally publishedYes

ASJC Scopus subject areas

  • Hematology


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