Development and preclinical validation of a novel covalent ubiquitin receptor Rpn13 degrader in multiple myeloma.

Proteasome inhibition is an effective treatment for multiple myeloma (MM); however, targeting different components of the ubiquitin-proteasome system (UPS) remains elusive. Our RNA-interference studies identified proteasome-associated ubiquitin-receptor Rpn13 as a mediator of MM cell growth and survival. Here, we developed the first degrader of Rpn13, WL40, using a small-molecule-induced targeted protein degradation strategy to selectively degrade this component of the UPS. WL40 was synthesized by linking the Rpn13 covalent inhibitor RA190 with the cereblon (CRBN) binding ligand thalidomide. We show that WL40 binds to both Rpn13 and CRBN and triggers degradation of cellular Rpn13, and is therefore first-in-class in exploiting a covalent inhibitor for the development of degraders. Biochemical and cellular studies show that WL40-induced Rpn13 degradation is both CRBN E3 ligase- and Rpn13-dependent. Importantly, WL40 decreases viability in MM cell lines and patient MM cells, even those resistant to bortezomib. Mechanistically, WL40 interrupts Rpn13 function and activates caspase apoptotic cascade, ER stress response and p53/p21 signaling. In animal model studies, WL40 inhibits xenografted human MM cell growth and prolongs survival. Overall, our data show the development of the first UbR Rpn13 degrader with potent anti-MM activity, and provide proof of principle for the development of degraders targeting components of the UPS for therapeutic application.

Hyaluronic acid tethered pH-responsive alloy-drug nanoconjugates for multimodal therapy of glioblastoma: An intranasal route approach.

In the present investigation, FePt alloy nanoparticles were synthesized with controlled size and elemental composition followed by surface modification using (3-Aminopropyl) triethoxysilane (APTES). Lenalidomide was covalently bound to FePt-NH2 by pH sensitive hydrazone bonding. Hyaluronic acid was conjugated to amino groups of APTES while lactoferrin (Lf) was directly conjugated to excess carboxylic group present on hyaluronic acid (HA) to form surface modified pH sensitive alloy-drug nanoconjugates (SPANs). The multifunctional nanoconjugates were characterized and evaluated using extensive in vitro and in vivo techniques. The nanoconjugates demonstrated excellent heating ability on exposure to alternating magnetic field and near-infrared laser irradiation. The acidic microenvironment of lysozome triggered release of LND from SPANs. Owing to leaching of Fe and Pt contents, SPANs demonstrated ability to generate reactive oxygen species (ROS) in U87MG cell line which further enhanced therapeutic effect of SPANs. Significant difference in cell viability suppression was observed in in vitro photothermal, chemo-photothermal and chemo-magnetophotothermal killing of cancer cells using SPANs in U87MG cell lines. Significant difference in heating ability and cell cytotoxicity of SPANs in comparison to alternative magnetic field and NIR irradiation was observed for DUAL-mode exposure of SPANs. The results of cellular internalization study showed efficient internalization of SPANs inside U87MG cells. The in vivo results (both qualitative and quantitative) confirmed enhanced uptake of SPANs in brain after intranasal administration with enhanced nasal and mucus penetration owing to presence of Lf. No significant interaction was observed with ECM and mucin due to presence of carboxyl group on SPANs.

Lenalidomide enhances MOR202-dependent macrophage-mediated effector functions via the vitamin D pathway.

Macrophages are key mediators of the therapeutic effects exerted by monoclonal antibodies, such as the anti-CD38 antibody MOR202, currently introduced in multiple myeloma (MM) therapy. Therefore, it is important to understand how antibody-mediated effector functions of myeloma-associated macrophages (MAMs) are regulated. Here, we focused on the effects of vitamin D, a known regulator of macrophage effector functions. Consequently, it was the aim of this study to assess whether modulation of the vitamin D pathway alters the tumoricidal activity of MAMs. Here, we demonstrate that MAMs display a defective vitamin D pathway with reduced expression level of CYP27B1 and limited tumoricidal activity which can be restored by the IMiD lenalidomide in vitro. Furthermore, our data indicate that the vitamin D pathway of MAMs from MM patients does recover during an IMiD-containing therapy shown by an improved MOR202-mediated cytotoxic activity of these MAMs against primary MM cells ex vivo. Here, the ex vivo cytotoxic activity could be further enhanced by vitamin D supplementation. These data suggest that vitamin D holds a key role for the effector functions of MAMs and that vitamin D supplementation in IMiD combination trials could further increase the therapeutic efficacy of anti-CD38 antibodies such as MOR202, which remains to be investigated in clinical studies.