antitumor and immunomodulatory activities of 1,2,4-oxadiazole derivatives.

Melanoma is the most aggressive and lethal type of skin cancer, responsible for approximately 60,000 deaths annually. The main strategy for treating melanoma is surgery to completely remove the lesion and its margins. However, for more advanced cases with a high recurrence rate, the preferred approach is to combine chemotherapy with immunotherapy treatments. Tumor-associated macrophages (TAMs) are the most abundant leukocytes in solid tumors. Current immunotherapy approaches target TAMs by inhibiting pro-tumoral TAMs and activating anti-tumoral TAMs, repolarizing them to the M1 phenotype. The antitumor and immunomodulatory activities of molecules derived from 1,2,4-oxadiazole, as demonstrated in the literature, highlight the potential of this class as a source of promising candidates for therapeutic applications. Thus, the present study aims to evaluate the antitumor and immunomodulatory effects of the synthetic derivative 1,2,4-oxadiazole, N-cyclohexyl-3-(3-methylphenyl)-1,2,4-oxadiazole-5-amine (1,2,4-oxadiazole derivative 2), in melanoma cells and murine Bone Marrow-Derived Macrophages (BMDMs). Cytotoxicity in B16-F10 and BMDMs cells was assessed using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT method. 1,2,4-oxadiazole derivative 2 exhibited antiproliferative effects on both cell lines, being 2.6 times more selective for B16-F10. Necrosis was identified as the active induced death pathway. BMDMs isolated and exposed to 1,2,4-oxadiazole derivative 2 polarize to the M1 phenotype and induce TNF-α at a concentration of 64.34 μM. Exposure to melanoma murine supernatants also promotes M1 polarization. Supernatants containing traces of 1,2,4-oxadiazole derivative 2 (Supernatants B, C, and D) increased the percentage of M1 cells compared to Supernatant A, as well as elevated levels of nitrite, TNF-α, and IL-12. 1,2,4-oxadiazole derivative 2 combined with Supernatant A and 1,2,4-oxadiazole derivative 2 combined with LPS also resulted in higher M1 polarization, suggesting a synergistic effect on M1 polarization and TNF-α production. Our findings underscore the significance of the 1,2,4-oxadiazole compound class and highlight the potential of 1,2,4-oxadiazole derivative 2 as an antitumoral and immunotherapeutic agent.