Tarsus Pharmaceuticals, Inc. TARS

The business

Tarsus sells one drug that matters: Xdemvy, a prescription eye drop cleared by the FDA in July 2023 for Demodex blepharitis, an itchy, crusty eyelid condition caused by microscopic mites that colonize the lash line and leave tell-tale waxy collars at the base of the lashes. It is the first and only drug approved for the condition. A patient uses it twice a day for six weeks. The active ingredient, lotilaner, is the same mite-and-tick killer sold to veterinarians, licensed from Elanco for human use. It paralyzes the mite by jamming a nerve channel the drug's makers say human cells do not share (Saturn-1, NCT04475432, and Saturn-2, NCT04784091, the two pivotal trials). The moat is plain: Tarsus got there first, holds the patents, and no rival has an approved competitor. An eye-doctor sales force and a heavy direct-to-consumer campaign, the "Time to be seen" ads, do the rest. Behind Xdemvy sit early bets: oral lotilaner to prevent Lyme disease, in the Phase 2a Carpo trial, and a version aimed at rosacea.