CRISPR/Cas9 technology abolishes theBCR/ABL1oncogene in chronic myeloid leukemia and restores normal hematopoiesis

Abstract

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disease produced by a unique oncogenic event involving the constitutively active tyrosine kinase (TK) BCR-ABL1. TK activity explains most features of CML, such as tumor development and maintenance. TK-inhibitory (TKI) drugs have changed its prognosis and natural history. Unfortunately, since ABL1 gene remains unaffected by TKIs, most patients should be treated with lifelong oral medication, resistant mutations arise and adverse effects occur during treatment in almost 25% of patients To address this problem, we have designed a potentially definitive therapeutic alternative with CRISPR/Cas9 genome editing nucleases that target leukemic stem cells (LSCs). CRISPR-edited LSCs lose their tumorigenic capacity and restore their own multipotency. The strategy was evaluated for the first time in a CML mouse model and in orthotopic assays with primary LSCs from CML patients. In Both systems, CRISPR-edited LSCs repopulated and restored the normal hematopoiesis in immunodeficient NSG niches providing a significant therapeutic benefit. We show for the first time how CRISPR technology permanently interrupts and avoids the BCR/ABL1 oncogene expression in human and mouse LSCs suggesting that human CML is an ideal candidate for CRISPR therapy, and providing proof-of-principle for genome editing in CML patients.

CRISPR medicine for blood disorders: Progress and challenges in delivery

“…In this strategy, after electroporation of the CRISPR components, ex vivo edited hematopoietic stem/progenitor cells of the patients are transplanted back. Vuelta et al (2020) used electroporation for the delivery of the Cas9 RNP complex for disrupting BCR/ABL1 oncogene in leukemic stem cells. Transplantation of ex vivo edited cells restored normal hematopoiesis in NSG mice.…”

Future Approaches for Treating Chronic Myeloid Leukemia: CRISPR Therapy

“…Edited patient-derived CD34+ are capable of regenerating normal hematopoiesis in the bone marrow niche of NOD/SCID mice. [104] In 2018, Wenli Feng's group demonstrated that other genome-editing nucleases, like ZFN nucleases, achieved the abrogation of the BCR/ABL1 oncogene [95]. Using a pair of ZFNs targeting the exon 1 of BCR, a premature stop codon was created triggering a truncated oncoprotein.…”

“…Finally, Vuelta et al recently reported their design of a new CRISPR/Cas9 short-deletion system that efficiently interrupts the BCR/ABL1 oncogene in murine and human cell lines and, for the first time, in primary leukemic stem cells Sca1+ from a CML mouse model and CD34+ from human CML patients [ 104 ]. They demonstrated that CRISPR/Cas9-edited LSCs had impaired tumorigenic activity and fully restored capacity for multipotency.…”

Future Approaches for Treating Chronic Myeloid Leukemia: CRISPR Therapy

“…This new strategy induces a large genomic deletion in the tumor cells and shows great inhibition-specific tumor growth in a K562 xenograft model. Finally, Vuelta et al recently reported their design of a new CRISPR/Cas9 short-deletion system that efficiently interrupts the BCR/ABL1 oncogene in murine/human cell lines and, for the first time, in primary leukemic stem cells (CD34+) from a CML mouse model and from human CML patients [80]. They demonstrated that CRISPR/Cas9-edited LSCs had impaired tumorigenic activity and fully restored capacity for multipotency.…”