Annexin-directed beta-glucuronidase for the targeted treatment of solid tumors

作者：Guillen Katrin P; Ruben Eliza A; Virani Needa; Harrison Roger G^*

来源：Protein Engineering Design and Selection, 2017, 30(2): 85-94.

DOI：10.1093/protein/gzw063

• beta-glucuronidase
• enzyme prodrug therapy
• phosphatidylserine
• SN-38 glucuronide
• vascular targeted

Enzyme prodrug therapy has the potential to remedy the lack of selectivity associated with the systemic administration of chemotherapy. However, most current systems are immunogenic and constrained to a monotherapeutic approach. We developed a new class of fusion proteins centered about the human enzyme beta-glucuronidase (beta G), capable of converting several innocuous prodrugs into chemotherapeutics. We targeted beta G to phosphatidylserine on tumor cells, tumor vasculature and metastases via annexin A1/A5. Phosphatidylserine shows promise as a universal marker for solid tumors and allows for tumor type-independent targeting. To create fusion proteins, human annexin A1/A5 was genetically fused to the activity-enhancing 16a3 mutant of human beta G, expressed in chemically defined, fed-batch suspension culture, and chromatographically purified. All fusion constructs achieved >95% purity with yields up to 740 mu g/l. Fusion proteins displayed cancer selective cell-surface binding with cell line-dependent binding stability. One fusion protein in combination with the prodrug SN-38 glucuronide was as effective as the drug SN-38 on Panc-1 pancreatic cancer cells and HAAE-1 endothelial cells, and demonstrated efficacy against MCF-7 breast cancer cells. beta G fusion proteins effectively enable localized combination therapy that can be tailored to each patient via prodrug selection, with promising clinical potential based on their near fully human design.

• 出版日期2017-2