The new Russian agent Hexasens-lio for fluorescence diagnosis and photodynamic therapy for malignancies
The paper deals with the preclinical study of the new Russian agent Hexasens-lio (HE) based on 5-ALA hexyl ester, synthesized by the original procedure, versus the officinal agent Alasens based on 5-ALA. When orally administered, 5-ALA-based HE was shown to induce in animal tissues red fluorescence whose spectrum in the shape and positions of maxima (630 nm and 705 nm) is characteristic of PPIX fluorescence. The distribution of hexasens- and alasens-induced porphyrins was similar in mice. Hexasens-induced fluorescence was detectable in a number of tumors of both primary and metastatic foci. Photodynamic therapy (PDT) with hexasens was effective in suppressing the growth of transplantable non-pigmented tumors. No adverse reactions caused by oral hexasens were found. The intravesicular use of Hexasens-lio at a concentration of 0.002% led to the high production of PPIX in the rabbit urinary bladder epithelium, which was comparable with that of 3% 5-ALA solution. When hexasens was increased by 20 times (0.01%), there were no adverse urinary bladder epithelial reactions. The findings suggest that clinical trials of Hexasens-lio as an agent for tumor fluorescence diagnosis and PDT are promising.