Insights to biology and immunotherapy of osteosarcoma

Osteosarcoma is the most common primary tumor of the bone with the highest incidence in the first two decades of life. The incidence rate with 95% confidence is 4 for the range of 0-14 and 5 for the range of 0-19 cases pre million per year. Osteosarcoma is a rare malignant mesenchymal tumor with presence of mesenchymal cells and production of osteoid matrix (1). Distinct histological subtypes have been defined, but the biological behavior and the conven- tional approach to treatment have been similar for last cou- ple of decades without improvement in outcome. The biol- ogy of osteosarcoma is characterized with a high rate of lung metastasis. Disorganized genome seems to be the best description of genetic aberrations and changes in gene expression in osteosarcoma, with the most consistent finding, beside the p53 and RB dysregulation, significant an- euploidy and some evidence of massive disruption in the chromosomal structure (2). The metastatic cascade repre- sents a process where cell leaves primary tumor and in- vades the surrounding tumor microenvironment with intra- vascular and also extravascular invasion to the distant sites enabling the blood supply and growth to the secondary site and reengage to the new microenvironment. Mean- while, metastatic cell could be dormant in the „protective“ environment and then move to the secondary distant sites (3)...

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