Pharmacological inhibition of RAS overcomes FLT3 inhibitor resistance in FLT3-ITD+ AML through AP-1 and RUNX1.

AML is characterized by mutations in genes associated with growth regulation such as internal tandem duplications (ITD) in the receptor kinase FLT3. Inhibitors targeting FLT3 (FLT3i) are being used to treat patients with FLT3-ITD+ but most relapse and become resistant. To elucidate the resistance mechanism, we compared the gene regulatory networks (GRNs) of leukemic cells from patients before and after relapse, which revealed that the GRNs of drug-responsive patients were altered by rewiring their AP-1-RUNX1 axis.

A Cell-based Screening Method Using an Intracellular Antibody for Discovering Small Molecules Targeting Hard-to-drug Proteins.

Targeting hard-to-drug proteins, such as proteins functioning by protein-protein interactions (PPIs) with small molecules, is difficult because of the lack of well-defined pockets. Fragment or computational-based methods are usually employed for the discovery of such compounds, but no generic method is available to quickly identify small molecules interfering with PPIs. Here, we provide a protocol describing a generic method to discover small molecules inhibiting the interaction between an intracellular antibody and its target, in particular for proteins that are hard to make in recombinant form.

An antibody-drug conjugate with intracellular drug release properties showing specific cytotoxicity against CD7-positive cells.

Refractory T cell acute leukaemias that no longer respond to treatment would benefit from new modalities that target T cell-specific surface proteins. T cell associated surface proteins (the surfaceome) offer possible therapy targets to reduce tumour burden but also target the leukaemia-initiating cells from which tumours recur. Recent studies of the T cell leukaemia surfaceome confirmed that CD7 is highly expressed in overt disease.

Competitive SPR using an intracellular anti-LMO2 antibody identifies novel LMO2-interacting compounds.

The use of intracellular antibodies as templates to derive surrogate compounds is an important objective because intracellular antibodies can be employed initially for target validation in pre-clinical assays and subsequently employed in compound library screens. LMO2 is a T cell oncogenic protein activated in the majority of T cell acute leukaemias. We have used an inhibitory intracellular antibody fragment as a competitor in a small molecule library screen using competitive surface plasmon resonance (cSPR) to identify compounds that bind to LMO2.

Pan RAS-binding compounds selected from a chemical library by inhibiting interaction between RAS and a reduced affinity intracellular antibody.

Intracellular antibodies are valuable tools for target validation studies for clinical situations such as cancer. Recently we have shown that antibodies can be used for drug discovery in screening for chemical compounds surrogates by showing that compounds could be developed to the so-called undruggable RAS protein family. This method, called Antibody-derived compound (Abd) technology, employed intracellular antibodies binding to RAS in a competitive surface plasmon resonance chemical library screen.

Immunopolymer Lipid Nanoparticles for Delivery of Macromolecules to Antigen-Expressing Cells.

Macromolecules such as antibodies and antibody fragments have been reported to interfere with intracellular targets, but their use is limited to delivery systems where expression is achieved from vectors such as plasmids or viruses. We have developed PEGylated nanoparticles of poly-lactic acid (PLA), including the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), which are functionalized with monoclonal anti-CD7, anti-CD53, or anti-GPR56 antibodies for receptor-mediated endocytic delivery into T-cell leukemia cell lines. Incorporation of DOTAP as the lipid component of the PLA nanoparticles enhanced the release of the immuno-nanoparticles from the endosomes into the cytosol compared to nanoparticles made from PLA alone.

A potent KRAS macromolecule degrader specifically targeting tumours with mutant KRAS.

Tumour-associated KRAS mutations are the most prevalent in the three RAS-family isoforms and involve many different amino-acids. Therefore, molecules able to interfere with mutant KRAS protein are potentially important for wide-ranging tumour therapy. We describe the engineering of two RAS degraders based on protein macromolecules (macrodrugs) fused to specific E3 ligases.

Development of embryonic and adult leukemia mouse models driven by MLL-ENL translocation.

Rearrangements involving the mixed lineage leukemia gene (MLL) are found in the majority of leukemias that develop within the first year of age, known as infant leukemias, and likely originate during prenatal life. MLL rearrangements are also present in about 10% of other pediatric and adult acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). These translocations and others occurring in early life are associated with a dismal prognosis compared with adult leukemias carrying the same translocations.

Multimeric antibodies with increased valency surpassing functional affinity and potency thresholds using novel formats.

The success of therapeutic antibodies is largely attributed for their exquisite specificity, homogeneity, and functionality. There is, however, a need to engineer antibodies to extend and enhance their potency. One parameter is functional affinity augmentation, since antibodies matured in vivo have a natural affinity threshold.