Leukemia最新文献

CAR T-cell products targeting lineage-specific cell-of-origin antigens, thereby eliminating both tumor and healthy counterpart cells, are currently clinically approved therapeutics in B- and plasma-cell malignancies. While they represent a major clinical improvement, they are still limited in terms of efficacy by e.g. single, sometimes low-expressed antigen targeting, and in terms of safety by e.g., lack of on-off activity. Successful cell-of-origin non-discriminative targeting of heterogeneous hematopoietic stem and progenitor cell malignancies, such as acute myeloid leukemia (AML), will require antigen-versatile targeting and off-switching of effectors in order to then allow rescue by hematopoietic stem cell transplantation (HSCT), preventing permanent myeloablation. To address this, we developed adaptor-CAR (AdFITC-CAR) T-cells targeting fluoresceinated AML antigen-binding diabody adaptors. This platform enables the use of adaptors matching the AML-antigen-expression profile and conditional activity modulation. Combining adaptors significantly improved lysis of AML cells in vitro. In therapeutic xenogeneic mouse models, AdFITC-CAR T-cells co-administered with single diabody adaptors were as efficient as direct CAR T-cells, and combinatorial use of adaptors further enhanced therapeutic efficacy against both, cell lines and primary AML. Collectively, this study provides proof-of-concept that AdFITC-CAR T-cells and combinations of adaptors can efficiently enhance immune-targeting of AML.

Internal tandem duplications in the FMS-like tyrosine kinase-3 (FLT3-ITD) are common mutations in acute myeloid leukemia (AML). Proteolysis-targeting chimeras (PROTACs) that induce proteasomal degradation of mutated FLT3 emerge as innovative pharmacological approach. Molecular mechanisms that control targeted proteolysis beyond the ubiquitin-proteasome-system are undefined and PROTACs are the only known type of FLT3 degraders. We report that the von-Hippel-Lindau ubiquitin-ligase based FLT3 PROTAC MA49 (melotinib-49) and the FLT3 hydrophobic tagging molecule MA50 (halotinib-50) reduce endoplasmic reticulum-associated, oncogenic FLT3-ITD but spare FLT3. Nanomolar doses of MA49 and MA50 induce apoptosis of human leukemic cell lines and primary AML blasts with FLT3-ITD (p < 0.05-0.0001), but not of primary hematopoietic stem cells and differentiated immune cells, FLT3 wild-type cells, retinal cells, and c-KIT-dependent cells. In vivo activity of MA49 against FLT3-ITD-positive leukemia cells is verified in a Danio rerio model. The degrader-induced loss of FLT3-ITD involves the pro-apoptotic BH3-only protein BIM and a previously unidentified degrader-induced depletion of protein-folding chaperones. The expression levels of HSP90 and HSP110 correlate with reduced AML patient survival (p < 0.1) and HSP90, HSP110, and BIM are linked to the expression of FLT3 in primary AML cells (p < 0.01). HSP90 suppresses degrader-induced FLT3-ITD elimination and thereby establishes a mechanistically defined feed-back circuit.

The therapeutic potential of targeting PI3K/AKT/PTEN signalling in B-cell malignancies remains attractive. Whilst PI3K-α/δ inhibitors demonstrate clinical benefit in certain B-cell lymphomas, PI3K signalling inhibitors have been inadequate in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) in part, due to treatment related toxicities. Clinically, AKT inhibitors exhibit a differentiated tolerability profile offering an alternative approach for treating patients with B-cell malignancies. To explore how AKT inhibition complements other potential therapeutics in the treatment of DLBCL patients, an in vitro combination screen was conducted across a panel of DLCBL cell lines. The AKT inhibitor, capivasertib, in combination with the BCL-2 inhibitor, venetoclax, produced notable therapeutic benefit in preclinical models of DLBCL. Capivasertib and venetoclax rapidly induced caspase and PARP cleavage in GCB-DLBCL PTEN wildtype cell lines and those harbouring PTEN mutations or reduced PTEN protein, driving prolonged tumour growth inhibition in DLBCL cell line and patient derived xenograft lymphoma models. The addition of the rituximab further deepened the durability of capivasertib and venetoclax responses in a RCHOP refractory DLBCL in vivo models. These findings provide preclinical evidence for the rational treatment combination of AKT and BCL-2 inhibitors using capivasertib and venetoclax respectively alongside anti-CD20 antibody supplementation for treatment of patients with DLBCL.

Recent studies highlighted genetic aberrations associated with prognosis in Mantle Cell lymphoma (MCL), yet comprehensive testing is not implemented in clinical routine. We conducted a comprehensive genomic characterization of 180 patients from the European MCL network trials by targeted sequencing of peripheral blood DNA using the EuroClonality(EC)-NDC assay. The IGH::CCND1 fusion was identified in 94% of patients, clonal IGH-V-(D)-J rearrangements in all, and 79% had ≥1 somatic gene mutation. The top mutated genes were ATM, TP53, KMT2D, SAMHD1, BIRC3 and NFKBIE. Copy number variations (CNVs) were detected in 83% of patients with RB1, ATM, CDKN2A/B and TP53 being the most frequently deleted and KLF2, CXCR4, CCND1, MAP2K1 and MYC the top amplified genes. CNVs and mutations were more frequently observed in older patients with adverse impact on prognosis. TP53^mut, NOTCH1^mut, FAT1^mut TRAF2^del, CDKN2A/B^del and MAP2K1^amp were linked to inferior failure-free (FFS) and overall survival (OS), while TRAF2^mut, EGR2^del and BCL2^amp related to inferior OS only. Genetic complexity (≥3 CNVs) observed in 51% of analysed patients was significantly associated with impaired FFS and OS. We demonstrate that targeted sequencing from peripheral blood and bone marrow reliably detects diagnostically and prognostically important genetic factors in MCL patients, facilitating genetic characterization in clinical routine.

Acute erythroleukemia (AEL) is a rare subtype of acute myeloid leukemia with a poor prognosis. In this study, we established a novel murine AEL model with Trp53 depletion and ERG overexpression. ERG overexpression in Trp53-deficient mouse bone marrow cells, but not in wild-type bone marrow cells, leads to AEL development within two months after transplantation with 100% penetrance. The established mouse AEL cells expressing Cas9 can be cultured in vitro, induce AEL in vivo even in unirradiated recipient mice, and enable efficient gene ablation using the CRISPR/Cas9 system. We also confirmed the cooperation between ERG overexpression and TP53 inactivation in promoting the growth of immature erythroid cells in human cord blood cells. Mechanistically, ERG antagonizes KLF1 and inhibits erythroid maturation, whereas TP53 deficiency promotes proliferation of erythroid progenitors. Furthermore, we identified HDAC7 as a specific susceptibility in AEL by the DepMap-based two-group comparison analysis. HDAC7 promotes the growth of human and mouse AEL cells both in vitro and in vivo through its non-enzymatic functions. Our study provides experimental evidence that TP53 deficiency and ERG overexpression are necessary and sufficient for the development of AEL and highlights HDAC7 as a promising therapeutic target for this disease.