The dialyzable leukocyte extract Transferon inhibits tumor growth and brain metastasis in a murine model of prostate cancer.

Prostate cancer (PCa) is the second most frequently diagnosed cancer in men worldwide. Dialyzed Leukocyte Extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that improve clinical responses in various diseases. Here, we analyzed the effects of Transferon, a commercial DLE with characterized active pharmaceutical ingredient and proven batch-to-batch reproducibility, in preclinical models of PCa. We employed v-Src-transformed murine prostate epithelial (PEC-Src) cells, which recapitulate the transcriptional profiles in human PCa, can be grown in immunocompetent mice, and consistently form bone and brain metastases. In vitro, Transferon did not induce cytotoxicity nor alterations in migration /invasion of PEC-Src cells. In vivo, Transferon reduced metastatic dissemination after intracardiac injection of PEC-Src and inhibited tumor growth of subcutaneous isotransplants. The antineoplastic effect of Transferon correlated with changes in tumor infiltration, increased serum concentrations of IL-12 and CXCL1, and reduced levels of VEGF. Our results suggest that the antineoplastic effect produced by Transferon is due to its immunomodulatory activity and not by a direct effect on cancer cells, and indicate that Transferon could be beneficial as adjuvant therapy in PCa patients.