Cobimetinib R-enantiomer is the R-stereoisomer of Cobimetinib, a selective inhibitor of MEK, a protein kinase in the MAPK/ERK signaling pathway often dysregulated in cancer. While the S-enantiomer is the active pharmaceutical ingredient used in oncology for treating BRAF V600E-mutated unresectable or metastatic melanoma in combination with BRAF inhibitors like vemurafenib, the R-enantiomer is primarily utilized in pharmaceutical research. It serves as a reference standard, in enantioselectivity studies, or to investigate stereochemical effects on MEK inhibition potency and cancer cell growth suppression. Ongoing research explores its potential in comparative therapeutic models for various cancers involving the MAPK/ERK pathway.