Moreover, E7107 had the greatest effect on intron retention. This study indicates/suggests that mutated SF3B1 UM cells are more sensitive to the splicing inhibitor E7107 than wild-type SF3B1 UM cells.

P1, N=127, Terminated, Hemavant Sciences GmbH | N=200 --> 127 | Trial completion date: Dec 2024 --> Feb 2024 | Active, not recruiting --> Terminated | Trial primary completion date: Sep 2024 --> Feb 2024; The study was terminated after conducting an interim analysis of the available data where it became evident that the observed efficacy results were not in alignment with the initially set expectations.

Here, we showed that cohesin mutations are biomarkers of sensitivity to drugs targeting the splicing factor 3B subunit 1 (SF3B1) H3B-8800 and E-7107...Furthermore, we demonstrated that treatment of cohesin-mutant cells with SF3B1 modulators not only resulted in impaired DNA damage response and accumulation of DNA damage, but it sensitized cells to subsequent killing by poly(ADP-ribose) polymerase (PARP) inhibitors and chemotherapy and led to improved overall survival of PDX models of cohesin-mutant AML in vivo. Our findings expand the potential therapeutic benefits of SF3B1 splicing modulators to include cohesin-mutant MDS and AML.

Moreover, pladienolide B increases cytotoxic immune cell infiltration in the ID8 mouse model as a SF3B1 inhibitor and increases the expression of PD-L1 which can enhance the antitumor effect of αPDL1 in ovarian cancer. The data suggests that inhibition of SF3B1 improves the immune microenvironment of ovarian cancer and synergizes ICB immunotherapy, which provides preclinical evidence for the combination of SF3B1 inhibitor and ICB to ovarian cancer treatment.

In conclusion, we developed a precise gene editing strategy of human HSCs to identify prexasertib as a promising therapy for SF3B1m myeloid neoplasms, and implicate the mitotic function of CHK1 as a SF3B1m sensitivity. The safety and toxicity profiles displayed in early phase clinical trials make prexasertib a suitable agent for further clinical investigation in SF3B1m MDS and its advanced stages.

Using the H3B-8800 splicing modulator, we show, for the first time in CLL, cytotoxic effects in vitro in primary CLL samples and in SF3B1-mutated isogenic CLL cell lines, accompanied by major splicing changes and delayed leukemic infiltration in a CLL xenotransplant mouse model. H3B-8800 displayed preferential lethality towards SF3B1-mutated cells and synergism with the BCL2 inhibitor venetoclax, supporting the potential use of SF3B1 inhibitors as a novel therapeutic strategy in CLL.

We designed and synthesized novel 4-acetoxypentanamide derivatives of spliceostatin A, whose 4-acetoxypentenamide moiety is reduced (7), isomerized (8), or substituted with methyl at the α-position (9). The results of biological evaluation against AR-V7 and the docking analysis of each derivative suggest that the geometry of the 4-acetoxypentenamide moiety of spliceostatin A is important for its biological activity.

Pre-treatment of cohesin-mutant cells with H3B-8800 for 3 days increased their sensitivity to the PARP inhibitor talazoparib 10-fold, while the sensitivity of wild-type cells to talazoparib was unaffected (Figure 1A)...In addition to talazoparib, we demonstrated significantly improved overall survival of STAG2-mutant AML PDX mice receiving sequential treatment of E-7107 and standard induction chemotherapy (doxorubicin and cytarabine), further expanding this strategy beyond PARP inhibitors...In summary, our study identifies a critical connection between cohesin mutations and splicing modulation in AML, creating a novel therapeutic strategy for these patients with very limited treatment options and poor outcomes. Our findings not only expand the potential therapeutic benefits of SF3B1 splicing modulators to include cohesin-mutant MDS/sAML but we also propose this as a broader strategy for therapeutic targeting of other DNA damage-repair deficient cancers.

Moreover, IS1 and IS4 potentiated the sensitivity to gemcitabine in both conventional 2D monolayer and 3D spheroid cultures, and these results might be explained by the statistically significant increase in hENT1 expression (P < 0.05 vs. untreated control cells), potentially reversing PDAC chemoresistance. These results support further studies on new SF3B1 inhibitors and the role of RON/hENT1 modulation to develop effective drug combinations against PDAC.

We further demonstrate that clinically used SF3B1 inhibitors synergize with CHEK2 inhibitors and chemotherapeutic drugs to block leukemia growth. Our study provides the proof of principle for posttranslational regulation of splicing components and associated roles and therapeutic implications for the U2 complex in T cell leukemia.

P1, N=200, Recruiting, Hemavant Sciences GmbH | Trial completion date: Nov 2022 --> Dec 2024 | Trial primary completion date: Nov 2022 --> Sep 2024

Together, we highlight SF3B1 as a potential diagnostic and prognostic biomarker and an efficient pharmacological target in glioblastoma, offering a clinically relevant opportunity worth to be explored in humans.

Nevertheless, this set of simulations discloses that the K700E mutation and H3B-8800 binding affect the overall SF3b internal motion, which in turn may influence the way SF3b interacts with other spliceosome components. Finally, we unveil the existence of a putative druggable SF3b pocket in the vicinity of K700E that could be harnessed in future rational drug-discovery efforts to specifically target mutant SF3b.

Compound b1 and harmine were more efficient in protecting SH-SY5Y cells against 6-hydroxydopamine-induced cell death, an effect that was previously correlated to Dyrk1A inactivation in cells but not yet verified using chemical inhibitors. The presented dual inhibitors exhibited a novel activity profile encouraging for further testing in neurodegenerative disease models.

P1, N=200, Recruiting, H3 Biomedicine Inc. | Trial completion date: Apr 2022 --> Nov 2022 | Trial primary completion date: Apr 2022 --> Nov 2022

Elevated pre-treatment expression of aberrant transcripts of Transmembrane Protein 14C (TMEM14C), an SF3B1 splicing target encoding a mitochondrial porphyrin transporter, was observed in MDS patients experiencing RBC TI. In summary, H3B-8800 treatment was associated with mostly low-grade TAEs and induced RBC TI in a biomarker-defined subset of MDS.

Especially in the subgroup of MDS patients with RS, luspatercept showed high clinical activity for the treatment of anemia in the phase 2 (PACE-MDS) trial and subsequently in the phase 3 (MEDALIST) trial, which resulted in approval by both the US Food and Drug Administration and the European Medicines Agency in April 2020. Additional studies are needed to better understand the mechanism of action and pharmacodynamics of this novel agent in MDS.

Azacitidine + venetoclax, decitabine + venetoclax, and low-dose cytarabine + venetoclax are now standard treatments for newly diagnosed older or unfit patients with acute myeloid leukemia (AML). Venetoclax combination therapy is effective in many patients with RR-AML, and pretreatment molecular characteristics may predict outcomes. Trials that evaluate novel agents in combination with venetoclax therapy in patients with RR-AML that have adverse risk genomic features are warranted.

RAS mutations were enriched in patients with U2AF1 mutations and associated with inferior outcomes (median OS, 8 months). Comparable outcomes were observed between patients with vs without spliceosome mutations treated with HMA+VEN regimens, with specific co-mutation pairs demonstrating favorable outcomes.

Fusing thalidomide-the ligand of the cereblon ubiquitin ligase-to O4I2 led to a new PROTAC-O4I2, which selectively degraded SF3B1 and induced cellular apoptosis in a CRBN-dependent manner. In a Drosophila intestinal tumor model, PROTAC-O4I2 increased survival by interference with the maintenance and proliferation of stem cell. Thus, our finding demonstrates that SF3B1 is PROTACable by utilizing noninhibitory chemicals, which expands the list of PROTAC target proteins.

No abstract available

The use of ancestral reconstruction of genomic data sheds light on the unique clinical scenario described in this case report. By determining the mutational profile of tumors at several timepoints and deducing the most parsimonious relationship between them, we propose a reconstruction of their origin. We propose that blast progression originated from subclonal events with malignant potential, which coexisted with but did not originate from JAK2 p.V617F-positive ET. We conclude that the application of genomic reconstruction enhances our understanding of leukemogenesis by identifying the timing of molecular events, potentially leading to better chemotherapy choices as well as the development of new targeted therapies.

No abstract available

Proximity labeling (PL) however, can also highlight transient and negative effects - those interactions which lead to dissociation from the existing protein complex. Here we highlight the power of PL in combination with recombinant KSHV to study viral host interactions.

SF3B1 mutations occur in the full spectrum of myeloid disorders. We independently validated the favorable prognostication of IWG-PM-defined SF3B1-mut-MDS. However it may not provide sharp prognostication within MDS-SF3B1 where IPSS-R and TF comutations were prognostic-informative. Larger cohort studies are warranted to verify these findings and refine MDS-SF3B1 prognostication.

Pharmacological activation of PP2A with FTY-720 markedly compromised the growth advantage induced by the SF3B1 mutation in vitro and in vivo. Taken together, our data suggest a novel function for SF3B1 mutation in the Warburg effect, and this finding may offer a potential therapeutic strategy against PDAC with the SF3B1 mutation.

We critically review the dogma of low mutational load, the induction of immune-suppressive cells, and the expression of alternative immune checkpoint molecules. We argue that immunotherapy might still be an option for the treatment of UM.

No abstract available

Donor-derived CH was not associated with worse overall survival; however, patients with donor-derived CH were more likely to develop chronic GVHD requiring systemic immunosuppressive therapy (IST) (p=0.045), and were less likely to discontinue IST (p=0.03), compared to controls without donor-derived CH. We conclude that donor-derived CH does not have an adverse impact on relapse, survival, or engraftment outcomes, but may potentiate a graft versus leukemia effect reflected by increased chronic GVHD requiring IST.

The most frequent mutations in MM all effect the MAPK signalling pathway (48% of samples). Several inhibitors of this pathway exist and are already used with poor outcomes, primarily due to the rapid development of resistance. There is a strong immune presence within this tumour type, and by associating matched RNA sequencing data and immune-oncology data with tumour subtype, suitable combinational personalised therapies, such as immunotherapy and MAPK inhibitors, can be identified.

We also evaluate the possibility of generating novel antibodies against known point mutations by computationally assessing for chemical and structural features as well as epitope antigenicity of these targets. Our results not only summarize several genetic mutations and identify existing point mutation specific antibodies relevant to hematologic malignancies, but also reveal potential underdeveloped targets which merit further study.

Some of these expanded TCRs are also present in the corresponding tumors. CD8+ T cell clones specific for the neo-epitopes specifically recognize and kill SF3B1-mutated tumor cells, supporting the use of this new family of neo-antigens as therapeutic targets.

Splicing factor 3B subunit 1 (SF3B1) mutations define a distinct myelodysplastic syndromes (MDS) patient group with a relatively favourable disease course and high response rates to luspatercept...In addition, we illustrate that SF3B1-mutation type is associated with distinct immunophenotypic features, and show the impact of co-occurrence of a SF3B1 mutation and a deletion of chromosome 5q on bone marrow immunophenotype. These genotype-phenotype associations and phenotypic subtypes within SF3B1-MDS provide leads that may further refine prognostication and therapeutic strategies for this particular MDS subgroup.