The relationship of chemo-immunotherapy and graft materials used in bone cancers with the micro environment

Osteosarcoma is characterized by proliferation of malignant osteoblasts. As a result of the application of neo-adjuvant chemotherapies used in the treatment of osteosarcoma, a significant improvement in clinical outcomes was observed. However, post-operative recurrences continue to exist as a common problem. The search for a new approach to prevent recurrence is important in post-operative patients. The aim of the study is to evaluate the relationship between the microenvironment and the chemotherapeutic and immunotherapeutic agents absorbed in cement to be applied to prevent recurrence in vivo. After osteosarcoma K7M2 cells were cultured, appropriate doses of mifamurtide and ifosfamide were determined by in vitro experiments. 5 groups (7 animals / group) were formed as control, cement + SF, cement + ifosfamide, cement + mifamurtid and cement + ifosfamid + mifamurtid. K7M2 cells were transferred to the right gluteal region of Balb / c mice followed by tumor formation and related groups were applied. In addition, cement + SF, cement + ifosfamide and IP ifosfamide were applied to athymic nude mice. After seven days of observation, sacrification was performed and CD4, CD8, CD20, CD64, FAPA, NCR1 levels were evaluated immunohistochemically and with microenvironment. Expression levels were evaluated between the groups by Kruskal Wallis and subsequent Mann-Whitney U test and chi-square tests. P <0.05 was considered statistically significant. After in vitro studies interactions of cement prepared with ifosfamide and mifamurtide with osteosarcoma cell line, K7M2, were examined and the appropriate dose was calculated. Then the in vivo step of the study was started. It was studied in 2 different animal species (balb / c and nüde mice). As no tumor formation was observed in Balb / c mice, cement prepared with ifosfamide and mifamurtide was implanted in the area where the tumor cells were administered. Interactions of cements prepared with ifosfamide and mifamurtide were observed in the tumor microenvironment. In nude mice, tumors occurred within one month after subcutaneous injection. In these animals with no immune response, more effective findings were obtained from the group that was prepared and implanted with ifosfamidine cement compared to the IP group. Our findings support that local administration of ifosfamide and mifamurtide in bone cement may contribute to local treatment of osteosarcoma after surgery. Local treatment among postoperative biomaterials may be additive treatment options for preventing recurrence in osteosarcoma. Keywords: Osteosarcoma, Mifamurtide, ifosfamide, bone graft material