Abstract B29: CD163-positive tumor-associated macrophages and CD8-positive cytotoxic lymphocytes are powerful diagnostic markers for therapeutic stratification of osteosarcoma patients in the French OS 2006 trial

The French phase 3 trial (OS 2006) testing combining zoledronate (an osteoclast inhibitor) with chemotherapy and surgery did not improve the outcome of patients with osteosarcoma. To understand this unexpected result, the presence of infiltrating immune cells was investigated in 124 biopsies of patients enrolled in the trial. The percentage of CD68/CD163 tumor-infiltrating macrophages, CD8 lymphocytes, osteoclasts, and the PD1/PDL-1 checkpoint...