(P 240) INVESTIGATING MACROPHAGE POPULATION VARIABILITY IN METASTATIC SARCOMA SAMPLES

Objective: Sarcomas are tumors of the bone and soft tissues that display high metastatic potential to the lung. Although the specific mechanisms remain elusive, studies in other malignancies have emphasized the role of the tumor microenvironment in metastasis. Macrophages play an imperative role in immunity and tumor progression. Here, we investigate the role of M1 (tumoricidal) and M2 (tumor permissive) macrophages in a panel of metastatic sarcoma samples.

Methods: This study utilizes a set of 3 tissue arrays containing 58 samples of tumor metastases from the lungs of patients with metastatic sarcoma. Vectra Polaris tumor microarrays used to investigate immune subsets of macrophages (CD68+/HLADR+/CD163- for M1, CD68+/HLADR-/CD163+ for M2). Cell counts per core and antibody were collected for bioinformatics analysis using R software.

Results: Different subpopulations of macrophages, M1 and M2, were identified with differential antibody staining. M2 to M1 ratio variability across multiple samples of a singular metastatic tumor will be correlated with patient outcomes, treatment response, and other clinical and demographic parameters.

Conclusion: With immunotherapy becoming more prevalent in cancer treatment, correct patient stratification is of the utmost importance. It is therefore imperative to understand the impact of the tumor microenvironment, heterogeneity, and immune cells on sarcoma metastasis and disease progression.