Anti-MIF nanobodies as a novel tool to improve cancer therapy

The macrophage migration inhibitory factor or MIF is a multifunctional cytokine that once bound to CD74, its main receptor, promotes the expression of pro-inflammatory cytokines, angiogenesis, and cell survival among other functions. MIF has been implicated as a biomarker of different diseases that have an inflammatory component, such as autoimmune diseases, metabolic disorders, systemic infections, and cancer. In this context, cross-reactive anti-MIF nanobodies (Nbs) were developed, and 11 different Nbs belonging to 7 different families were selected. We found that 2 out of the 11 Nbs significantly reduced TNF expression of murine and human LPS-stimulated cells. Interestingly, by generating tri-valent constructs, having anti-MIF Nbs on the ends and an anti-albumin Nb in the middle, to increase the half-life, the TNF expression was further reduced. More importantly, the tri-valent constructs were shown to be protective in a murine endotoxemia model, increasing mice survival. Based on these results and taking into consideration MIF’s pro-tumoral role, we decided to test whether these constructs can reduce tumor growth as monotherapy or increase the efficacy of current immunotherapies, such as PD-1 antibodies. We found that the anti-MIF monotherapy significantly reduces tumor growth compared to the untreated and the anti-PD-1 treated groups. The group receiving anti-MIF + anti-PD-1 also showed a slower growth compared to the untreated group, and the anti-PD-1 group, however, there are no significant differences between the mono- and combinatorial treatment regarding tumor growth, suggesting no additional contribution of the anti-PD-1 treatment. Within the tumor microenvironment, we found a significant increase of CD45+cells, CD4+ T cells, and IFN-γ CD8+ producing cells in the anti-MIF + anti-PD-1 treated group compared to the other groups. As a next step, we will include models which are less responsive to immunotherapy, where new alternatives are highly needed.