Efficiency of photosensitizer chlorin E6 dimethyl ether for photodynamic therapy of rat sarcoma M-1

Photodynamic therapy (PDT) is a local form of treatment for the complete eradication of solid malignant neoplasms (PDT). In this work, we studied the efficiency of PDT with the photosensitizer (PS) chlorin e6 dimethyl ether (DME Che6) in the treatment of positive for the mutant p53 gene sarcoma M-1. To assess the optimal time for tumor irradiation with laser the kinetics of PS accumulation in tumor and surrounding healthy tissues was studied. The tumor response to PDT was assessed with the use of the following criteria: tumor growth inhibition index (%); tumor complete regression (%); absolute growth rate (K) index, it is used in rats with tumor growth after the treatment; increase in the life expectancy in group of treated animals and the control group of tumor-bearing rats; the treatment response criterion - means the absence of signs of tumor recurrence within 90 days after therapy. On the 21st day after the treatment the PDT efficiency for tumor cells devitalization was assessed by examining the areas exposed to laser radiation and data of histological analysis. Results of the study allow us to state that DME Che6 has a high antitumor activity in the treatment of M-1 sarcoma. The maximum inhibitory effect of the PS on malignant neoplasms after PDT is achieved if time between the sensitizer introduction and the laser irradiation beginning is optimal. As a result of pathomorphological assessment of material after PDT, no survived tumor cells with expression of the mutant p53 protein were detected.