The one-drug-many-indications model has steadily grown in popularity since the early 2000s. But Irvine, California–headquartered Tarsus Pharmaceuticals is aiming to bring the model to XDEMVY (lotilaner), an antiparasitic drug that first won FDA-approval in dogs. After licensing lotilaner from Elanco, Tarsus won FDA approval for the drug, under the trade name XDEMVY, for the treatment of Demodex blepharitis, an eye condition caused by tiny mites. In July 2023, net sales hit $102.7 million in the second quarter of 2025, a 152% year-over-year increase.
Credit: Tarsus Pharmaceuticals
Now, Tarsus aims to expand the lotilaner pipeline with potential treatments for ocular rosacea, Lyme disease and malaria. Treatments for ocular rosacea (TP-04) and Lyme disease (TP-05) are in Phase 2 clinical studies; the TP-05 formulation is also moving into Phase 1 studies for malaria.
Lotilaner: “a portfolio in a drug”
Lotilaner kills parasites by inhibiting their GABA chloride channel, which paralyzes the parasite and then kills it in under 24 hours, explained Elizabeth Yeu, Chief Medical Officer at Tarsus.
“It really is like a portfolio in a drug,” Yeu said. Lotilaner is the active ingredient not only in XDEMVY, but also in several other treatments currently in clinical trials at Tarsus.
XDEMVY is an eye drop treatment that kills Demodex mites. Credit: Tarsus
Researchers at Tarsus were motivated to create a treatment for Demodex blepharitis, inflammation of the eyelids due to an excess of Demodex mites, after listening to doctors brought the undertreated disease to their attention, Yeu said. Before XDEMVY, there was no FDA-approved treatment for the disease.
In addition to Demodex blepharitis, Demodex mites may also be responsible for half of all cases of ocular rosacea, Yeu said. This knowledge led researchers at Tarsus to develop a gel formulation of lotilaner that patients can use around the eyes safely. This treatment is currently in Phase 2 studies.
Scientists at Tarsus were inspired to create the lotilaner pipeline due to unmet patient needs. The researchers knew that creating an organ-specific treatment would improve the efficacy, so they developed eye drops as well as a topical gel.
A possible preventative for Lyme disease and malaria
TP-05, an oral formulation of lotilaner, is currently in Phase 2 trials for Lyme disease and moving into Phase 1 for malaria. With this formulation, the lotilaner could work to kill the vector – a tick for Lyme disease and mosquitoes for malaria – when they bite a human who has taken the oral treatment.
For Lyme disease prevention, TP-05 would be a pill taken once every 30 days. Lotilaner’s long half-life allows it to remain effective for a longer time, Yeu explained. A Phase 2 study done with non-disease carrying ticks confirmed this timeline, showing that lotilaner remained effective for 30 days.
The CDC estimates that approximately 476,000 people could be diagnosed with Lyme disease annually in the U.S.“We have antibacterials to take care of the disease, but it’s such a devastating process. If it’s not caught in the acute phase, it has such a devastating effect in the chronic disease process,” said Yeu, “Can you imagine being able to just take one pill by mouth? That would be wonderful, especially when you’re thinking about 30 million Americans that are at high or moderate risk of contracting Lyme.”
Tarsus is also investigating the possibility of an oral formulation of lotilaner to prevent malaria. Similarly to lotilaner for Lyme, the drug would kill the mosquito, which is the vector for malaria.
Elizabeth Yeu, M.D., Chief Medical Officer at Tarsus Pharmaceuticals
“The global health implications of being able to potentially have a preventative medication, not only for something that is so endemic in the US, like Lyme disease, but globally, the impact that this could make, for example, in Africa, with the malaria programs. That kind of global health implication is just so impactful,” Yeu said.
Treating unmet needs
The drug discovery process of XDEMVY shows that researchers at Tarsus are dedicated to communicating with doctors to better serve patients’ unmet needs. Helping to treat underserved patient populations is what makes Tarsus unique, said Yeu.
“What makes me excited about being at Tarsus, and the future, is that we are really doing things differently in terms of how we develop different formulations of this silver bullet molecule, but also the areas that we’re entering, from a clinical development perspective, are really areas that are untapped, and there’s a lot of patients that are in need,” said Adrienne Kemp, senior director of Corporate Communications at Tarsus.
“At Tarsus, we’re committed to really creating transformational medications and being a growing eye care leader and a bio pharma leader,” Yeu said.
Filed Under: Drug Discovery, Drug Discovery and Development, Infectious Disease
