A novel therapeutic strategy for pancreatic cancer: targeting cell surface glycan using rBC2LC-N lectin-drug conjugate (LDC).

Various cancers, including pancreatic ductal adenocarcinoma (PDAC), remain intractable even with costly tumour-targeting antibody drugs. Because the outermost coatings of cancer cells are composed of cell-specific glycan layers (glycocalyx), lectins, proteins with glycan-binding potential, were evaluated for possible use as drug carriers in PDAC treatment. A human PDAC cell line with well-to-moderately differentiated properties (Capan-1) was subjected to lectin microarray analysis to identify specific lectin-glycan pairs. The selected lectin was fused with a bacterial exotoxin for the construction of a lectin-drug conjugate (LDC), and its safety and anti-tumour effects were evaluated. A specific affinity between rBC2LC-N (a recombinant bacterial C-type lectin) and Capan-1 was identified, and its positivity was confirmed in 69 human samples. In contrast to the belief that all lectins mediate harmful haemagglutination, rBC2LC-N did not cause haemagglutination with human erythrocytes and was safely administered to mice. The 50% inhibitory concentration of LDC to Capan-1 (1.04 pg/ml=0.0195 pmol/l) was 1/1000 lower than that reported for conventional immunotoxins. The intraperitoneal administration of LDC reduced the tumour weight from 390 mg to 130.8 mg (P<0.01) in an orthotopic model, and reduced the number of nodules from 48 to 3 (P<0.001) and improved survival from 62 to 105 days in a peritoneal dissemination model (P<0.0001). In addition, the effect of LDC was reproduced in nodules from patient-derived PDAC xenografts through intravenous injection. Herein, we show the concept of utilizing lectins as drug carriers to target glycans on the cancer cell surface, highlighting new insights into cancer treatments.

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