Marvelon suppresses MC38 tumor growth and promotes anti-tumor immunity.

Colorectal cancer is a prevalent and deadly malignancy globally, posing an important challenge due to its heterogeneity and treatment resistance. Although oral contraceptives have been shown to reduce the incidence of colorectal cancer, their impact on the anti-tumor effect of CD8+ T cells remains unclear. Here we show that the contraceptive Marvelon plays an important role in anti-MC38 tumor immunity. The contraceptive Marvelon significantly inhibits MC38 tumor growth in vivo. Marvelon treatment promotes IFN-γ expression in CD8+ tumor infiltrating lymphocytes, but shows dispensable impact on their exhausted profile. By further investigating the effects of Marvelon's primary components, Ethinylestradiol and Desogestrel, we reveal that Ethinylestradiol enhances IFN-γ production in Type 1 Cytotoxic T (Tc1) cells and significantly inhibits the viability of MC38 tumor cells, whereas Desogestrel exhibits minimal effects. This study not only redefines the role of oral contraceptives but also provides valuable insights for the development of novel immunotherapeutic strategies.