TDK conference 2020

Introduction and Objectives:

Every day, our body produces several thousand of neoplasm cells, however a functioning immune system can recognise and eliminate them. This scientific discovery serves as the basis of the antitumour immunotherapy, of which the major purpose is the stimulation of the immune system. There are two main therapeutic approaches to achieve this effect, on the one hand, there is application of tumour specific antigens, on the other hand, the aim is to use molecules, that are capable of causing a general immune response by activating the cells of the innate immune system. We have used two molecules belonging to the class of the Pathogen Associated Molecular Patterns, one of them was unmethylated CpG olygonucleotide, a ligand of TLR-9 and lippopolysaccharide (LPS) a component of the Gramm-negative bacterial cell wall, recognized by TLR-4, combined with an OX40 receptor- specific antibody (anti-OX40), which is expressed by the activated regulator T-cells. The objective of this study was to prove the effectivness of the afformentioned compounds by examining median survival time in an animal model, on a bladder cancer cell line.

Methods:

We have instilled a total of 1x10⁷ MB49 cells subcutaneusly, in a form of a 0.2 ml suspension, to the region of the left musculus biceps femoris. We have created three observation groups, each containing 10 C57BL6 mice. After eleven days of incubation, all mice bearing the size of 0.5-0.8 cm tumor were administered 50 µg CpG + 5 µg anti-OX40 or 500 ng LPS + 5 µg anti-OX40 three times and we have waited 3 days between each treatment. We have used autopsy and histopathology to identify the cause of death.

Results:

All the specimens from the control and LPS+anti-OX40 groups have died by the sixtieth day of the observation period, however, five mice from the CpG+anti-OX40 group were still alive (50%). The median survival time of mice vaccinated with CpG+anti-OX40 (60 days) and naive (35 days) was longer than the mice, who have received LPS+anti-OX40 treatment. A statistically significant increase in the median survival times was detected in the animals treated with CpG+anti-OX40 compared to the naive control (p<0,05) and LPS+anti-OX40 group (p<0,05). The LPS-anti-OX40 treatment had no statistically significant effect on the median survival times vs control. The whole experiment has lasted for 142 days, two additional mice has died or had to be euthanized due to poor general condition. The three remaining mice’s tumor has gone into remission.

Conclusion:

The compound containing CpG+anti-OX40 has shown increased antitumor activity compared to the naive control and LPS+anti-OX40 groups. The intratumoral traetment with LPS was not made anti-OX40 more potent and was not increased the median survival times.