GK-1 peptide reduces tumor growth, decreases metastatic burden, and increases survival in a murine breast cancer model.

GK-1 is a parasite-derived peptide adjuvant of 18 amino acid-length that enhances T-cell function and increases survival in B16-F10 melanoma tumor-bearing mice. This study was designed to evaluate in vivo the antitumor efficacy of GK-1 on 4T1 mouse mammary carcinoma. BALB/c mice with palpable primary tumors were weekly intravenously injected three times with saline solution or three different concentrations (10, 50, or 100μg per mouse) of GK-1. GK-1 significantly increased lifespan (p<0.0001) and reduced the primary tumor weight (p=0.014) and volume (p<0.0001) with respect to control mice, with no statistically significant differences among GK-1 doses. At the primary tumor, we found increased necrotic areas associated with a reduction in tumor mass, as well as an increase in the antitumor cytokine IL-12. Especially encouraging is the ability of GK-1 to reduce the number of lung metastasis (p=0.006) disregarding the dose used. The participation of IL-6 in metastasis development and the decreased levels of CCL-2, CCL-3, TNF-α, CXCL-9, GM-CSF, and b-FGF found in lungs of GK-1-treated mice is discussed. Our study supports the effectiveness of GK-1 as an antineoplastic agent that merits further exploration in combination with other therapeutic approaches in future translational studies.