The synergistic antitumor effect of Karanahan technology and in situ vaccination using anti-OX40 antibodies.

OBJECTIVES: Currently, there exist two approaches to the treatment of malignant neoplasms: the Karanahan technology and in situ vaccination, which are based on chronometric delivery of therapeutic agents to the tumor depending on the characteristics of tumor cells, as well as the immune status. The main purpose of this study was to experimentally prove the feasibility of combining the Karanahan technology and in situ vaccination with αOX40 antibodies into a single therapeutic platform to achieve a potent additive antitumor therapeutic effect. METHODS: BALB/c mice grafted with B-cellular lymphoma A20 were treated using the Karanahan technology consisting of intraperitoneal cyclophosphamide administrations and intratumoral DNA injections according to an individually determined therapeutic regimen, together with in situ vaccination with αOX40. A pathomorphological analysis of the organs of experimental animals that died during the initial attempt to combine the two technologies was carried out. An analysis of blood cell populations was performed to determine the safe time for antibody administration: the number of immune cells capable of activating systemic inflammation (CD11b+Ly-6C+, CD11b+Ly-6G+, CD3-NKp46+CD11b+), the presence of Fc receptor and OX40 on the surface of these cells, and the number of neutrophils activated to NETosis were analyzed. Based on the analysis results, the antitumor efficacy of various modes of combining the Karanahan technology and in situ vaccination was studied. RESULTS: When αOX40 was administered 5 h after each treatment using the Karanahan technology, mass death of mice caused by systemic inflammation and multiple organ failure was observed. The state of blood cells after the treatment using the Karanahan technology at the time points corresponding to antibody injections was analyzed to elucidate the reasons for this effect. It was found that at some time points, there occurs activation of the immune system and a powerful release (up to 16%) of monocytes and granulocytes carrying Fc receptor and OX40 on their surface into blood; when interacting with αOX40, they can activate the lytic potential of these cells. Activation of neutrophils to NETosis was also observed. Based on these findings, a study was carried out in different time regimes to combine the Karanahan technology and αOX40 injections. When αOX40 was injected into the points of minimal release of myeloid cells into the blood, increased survival rate and the greatest antitumor efficacy were observed: 37% of animals survived without relapses on day 100 after experiment initiation. Conclusions: The results obtained indicate that it is possible to combine the Karanahan technology and in situ vaccination with αOX40, with obligatory constant monitoring of the number of myeloid cells in peripheral blood to determine the safe time for antibody injection.