Non-muscle invasive bladder cancer is one of the most frequent forms of cancer. Commonly, the superficial tumor is removed by a minimal invasive surgery, mostly followed by the intravesical instillation of cytostatic agents. Although the initial treatment is usually successful, the recurrence rate is extraordinary high, which might be grounded in limiting factors during instillation, such as the high resistance of the bladder wall and the constant dilution with the permanently produced urine reducing the probability of interaction between the drug and the target cell. To overcome these limitations, we introduce a lectin-mediated drug delivery system consisting of wheat germ agglutinin as targeter, poly-l-glutamic acid as backbone and the active pharmaceutical ingredient (API) doxorubicin that should prolong the residence time in the bladder cavity. The optimized WGA-PGA-Doxo conjugate revealed an API load of 81 molecules per mole backbone and convinced in urothelial cell monolayer studies with an up to 56-fold higher cell-binding potential than pure doxorubicin. Additionally, the highly substituted drug delivery system not only internalized into urothelial cells, but also inhibited cell viability up to 99%.
The combination of the high drug load with the promising cell-associative properties, which also revealed a higher affinity to malignant than to healthy urothelial cells, and the proven cytotoxic potential might lead to an improved efficacy of intravesical chemotherapy.