R1FF-MMAE

**R1FF-MMAE** is an investigational, site-specific protein-drug conjugate comprising the Fu1-Fu2 leucine-rich repeat-containing G protein-coupled receptor-binding domain of R-spondin 1 linked through a cleavable valine-citrulline-para-aminobenzyl carbamate linker to monomethyl auristatin E. The R-spondin 1 domain selectively binds leucine-rich repeat-containing G protein-coupled receptors 4, 5, and 6 on tumor cells, promoting cellular uptake and intracellular release of the microtubule-disrupting MMAE payload. It showed low-nanomolar, LGR-dependent cytotoxicity in tumor cell lines and antitumor activity in ovarian cancer xenograft models, including following intravenous administration, but remains a preclinical research-stage therapeutic construct. ([sciencedirect.com](https://www.sciencedirect.com/org/science/article/abs/pii/S1043180221000173))

Other names

R1FF-MMAER-1FF-MMAER 1FF-MMAE