Development of long-acting formulations for hydrophobic Kifunensine analogues as potent inhibitors of type I mannosidase enzymes

Aberrant protein glycosylation is known to induce immune suppression, which can contribute to cancer malignancy and metastasis. The enzymes responsible for glycan biosynthesis may be modulated as a therapeutic strategy to improve the anticancer immune response. Kifunensine is a potent inhibitor of one of these enzymes, type I α-mannosidase, which can increase cell surface glycosylation through upregulation of high mannose N-glycans over branched and complex N-glycans. However, the high polarity of Kifunensine limits its cell permeability. Here, we report two hydrophobic analogues of Kifunensine designed for improved cell permeability. The hydrophobic analogues were formulated in an ethyl oleate oil vehicle to prolong release in vivo . The therapeutic efficiency of the developed formulation was examined using an immunocompetent mice model of colon cancer, which showed a marginal delay in the tumor growth with treatment. Immunofluorescence analysis demonstrated overexpression of high mannose N-glycans after treatment with both analogues, but only a slight increase in immune cell infiltration was observed. While previously reported studies showed significant upregulation of immune cells with Kifunensine, the present study suggests that Kifunensine may have limited efficacy as a monotherapy in colon cancer. • Ethyl oleate was shown to load the lipophilic Kifunensine analogues and sustain their release • The study supports the application of cyanovirin-N lectin for the detection of cells displaying high mannose N-glycans • Lipophilic Kifunensine analogues significantly upregulated high mannose N-glycans • The most lipophilic Kifunensine analogue (JDW-II-008) showed marginal antitumor activity compared to the parent drug • A slight immune cells infiltration was observed following Kifunensine analogues treatment