Anti-BAFF-R antibody VAY-736 demonstrates promising preclinical activity in CLL and enhances effectiveness of ibrutinib.

The Bruton tyrosine kinase inhibitor (BTKi) ibrutinib has transformed chronic lymphocytic leukemia (CLL) therapy but requires continuous administration. These factors have spurred interest in combination treatments. Unlike with chemotherapy, CD20-directed antibody therapy has not improved the outcome of BTKi treatment. Whereas CD20 antigen density on CLL cells decreases during ibrutinib treatment, the B-cell activating factor (BAFF) and its receptor (BAFF-R) remain elevated. Furthermore, BAFF signaling via noncanonical NF-κB remains elevated with BTKi treatment. Blocking BAFF interaction with BAFF-R by using VAY-736, a humanized defucosylated engineered antibody directed against BAFF-R, antagonized BAFF-mediated apoptosis protection and signaling at the population and single-cell levels in CLL cells. Furthermore, VAY-736 showed superior antibody-dependent cellular cytotoxicity compared with CD20- and CD52-directed antibodies used in CLL. VAY-736 exhibited in vivo activity as a monotherapy and, when combined with ibrutinib, produced prolonged survival compared with either therapy alone. The in vivo activity of VAY-736 is dependent upon immunoreceptor tyrosine-based activation motif (ITAM)-mediated activation of effector cells as shown by using an ITAM-deficient mouse model. Collectively, our findings support targeting the BAFF signaling pathway with VAY-736 to more effectively treat CLL as a single agent and in combination with ibrutinib.

Therapeutic CD94/NKG2A blockade improves natural killer cell dysfunction in chronic lymphocytic leukemia.

Natural killer (NK)-cell count is predictive of chronic lymphoid leukemia (CLL) disease progression and their dysfunction is well documented, but the etiology of this is currently lacking. CLL cells have been shown to over-express HLA-E, the natural ligand for NKG2A expressed on NK-cells that generates a distinct negative signal relative to direct NK-cell cytotoxicity in other disease models. Utilizing a novel anti-NKG2A monoclonal blocking antibody (mAb), monalizumab, we explored the in vitro preclinical activity of targeting the NKG2A receptor, and the NKG2A/HLA-E interaction as a mechanism of tumor evasion in CLL patients. Our work confirmed overexpression of HLA-E on CLL B-cells and demonstrated NKG2A expression on CD56+/16+ NK-cells from CLL patients. We also demonstrate that blocking NKG2A on CLL NK-cells was sufficient to restore direct cytotoxicity ability of NK-cells against HLA-E-expressing targets without impacting NK-cell mediated antibody-dependent cellular cytotoxicity. Additionally, we proved the specificity of monalizumab in blocking NKG2A through Fc-blocking mechanisms. This paper provides justification for the potential clinical utility of monalizumab in the treatment of patients with CLL.

Daunorubicin-Loaded DNA Origami Nanostructures Circumvent Drug-Resistance Mechanisms in a Leukemia Model.

Many cancers show primary or acquired drug resistance due to the overexpression of efflux pumps. A novel mechanism to circumvent this is to integrate drugs, such as anthracycline antibiotics, with nanoparticle delivery vehicles that can bypass intrinsic tumor drug-resistance mechanisms. DNA nanoparticles serve as an efficient binding platform for intercalating drugs (e.g., anthracyclines doxorubicin and daunorubicin, which are widely used to treat acute leukemias) and enable precise structure design and chemical modifications, for example, for incorporating targeting capabilities. Here, DNA nanostructures are utilized to circumvent daunorubicin drug resistance at clinically relevant doses in a leukemia cell line model. The fabrication of a rod-like DNA origami drug carrier is reported that can be controllably loaded with daunorubicin. It is further directly verified that nanostructure-mediated daunorubicin delivery leads to increased drug entry and retention in cells relative to free daunorubicin at equal concentrations, which yields significantly enhanced drug efficacy. Our results indicate that DNA origami nanostructures can circumvent efflux-pump-mediated drug resistance in leukemia cells at clinically relevant drug concentrations and provide a robust DNA nanostructure design that could be implemented in a wide range of cellular applications due to its remarkably fast self-assembly (≈5 min) and excellent stability in cell culture conditions.