We treated 7 patients with B-cell acute lymphoblastic leukemia (B-ALL) harboring rearrangement of the mixed lineage leukemia (MLL) gene with CD19 CAR-T cells.
We demonstrate that CRLF2 is overexpressed in approximately 15% of adult and high-risk pediatric B-ALL that lack MLL, TCF3, TEL, and BCR/ABL rearrangements, but not in B-ALL with these rearrangements or other lymphoid malignancies.
Up-regulation of miR-196b coincides with reduced DNA methylation at CpG islands in the promoter regions of miR-196b and the entire HOXA cluster in MLL-rearranged cases compared to in cases of non-MLL precursor B-cell acute lymphoblastic leukemia and normal bone marrow (P<0.05), suggesting an epigenetic origin for miR-196b over-expression.
Together, our data suggest that IGF2BP3-mediated targeting of oncogenic transcripts may represent a critical pathogenetic mechanism in MLL-rearranged B-ALL and support IGF2BP3 and its cognate RNA-binding partners as potential therapeutic targets in this disease.
To gain insight into the genomic landscape of infant MLL-AF4 pro-B ALL we performed whole genome sequencing of diagnostic leukemic blasts and matched germline samples from three MLL-AF4 pro-B ALL infants.
This is the first report of a recurrent chromosome rearrangement targeting the HOXA gene cluster in T-cell malignancies resulting in deregulated HOXA gene expression (particularly HOXA10 and HOXA11) and is in keeping with a previous report suggesting HOXA deregulation in MLL-rearranged T- and B cell lymphoblastic leukemia as the key factor in leukaemic transformation.
These findings uncover MLL-dependent transcriptional activation of BCL6 as a previously unrecognized requirement of malignant transformation by oncogenic MLL fusions and identified BCL6 as a novel target for the treatment of MLL-rearranged B-ALL.
These findings suggest that MSCs may be in part tumor-related, highlighting an unrecognized role of the BM milieu on the pathogenesis of MLL-AF4(+) B-ALL.
These cases show that B-ALL with MLL rearrangement, especially the t(9;11) translocation, can express a 'mature' B-cell phenotype and may represent a distinct subset.
The pathogenesis of t(4;11)/KMT2A-AFF1<sup>+</sup> (MLL-AF4<sup>+</sup>) infant B-cell acute lymphoblastic leukemia remains difficult to model, and the pathogenic contribution in cancer of the reciprocal fusions resulting from derivative translocated-chromosomes remains obscure.
The partial nontandem duplication of the MLL (ALL1) gene is a novel rearrangement that generates three distinct fusion transcripts in B-cell acute lymphoblastic leukemia.
The LAF4 protein was homologous to AF4 and AF5q31 proteins that are fused to MLL in infant early pre-B ALL and the breakpoint of LAF4 was located within the region homologous to the transactivation domain of AF4 and AF5q31.
Poor prognosis BCR-ABL and MLL-AF4 was detected in two-thirds of pediatric B-ALL and is likely to be the reason for the already reported poor survival of childhood ALL in South-East Asia.
Our data identify CD10- cytoplasmic immunoglobulin-positive pre-B ALL as a rare (2.2%) but distinct immuno-subtype of adult ALL that is characterized by a high MLL rearrangement rate and a worse outcome.
However, rare cases of mature B-ALL with non-L3 morphology and MLL-AF9 fusion have been reported, and such cases are characterized by a rapid and aggressive clinical course.
However, based on currently available data, we propose that consolidative HCT post-CART therapy be considered for all HCT-eligible patients and especially for pediatric patients with KMT2A-rearranged B-cell acute lymphoblastic leukemia.
Furthermore, the clinical features of this patient with the MLL-AF5q31 fusion transcript, characterized by the early pre-B phenotype (CD10(-)/CD19(+)) and poor outcome, were similar to those of patients having MLL-AF4 chimeric transcripts.