Tarsus Pharmaceuticals announced that it has dosed the first participant in the Calliope Phase 2 trial of TP‑05, an oral tablet designed to kill Lyme‑infected ticks before disease transmission. The randomized, double‑blind, placebo‑controlled study will enroll roughly 700 healthy adults at risk for Lyme disease across endemic U.S. regions, with enrollment expected to finish during the 2026 tick season and topline results slated for the first half of 2027.
TP‑05 expands Tarsus’s lotilaner platform beyond its ophthalmic product XDEMVY. XDEMVY, approved for Demodex blepharitis, generated $151.7 million in net product sales in Q4 2025 and contributed $451.4 million to full‑year 2025 sales, with guidance of $670‑$700 million for 2026. The new program targets an estimated 35 million Americans at moderate to high risk of Lyme disease, a market that currently has no approved pharmacologic prevention.
The Calliope trial is a significant step toward a potential first FDA‑approved on‑demand oral prophylactic for Lyme disease. While the milestone is early, it signals Tarsus’s intent to diversify revenue beyond its single product and leverage existing manufacturing and regulatory expertise.
CEO Bobby Azamian said, “For decades, Lyme disease management has focused on treating infection after it occurs. We believe there is an opportunity to fundamentally shift that paradigm toward prevention by targeting the ticks that transmit the disease. The Calliope trial represents an important step in developing what could potentially be the first FDA‑approved on‑demand oral prophylactic option designed to help prevent Lyme disease.” This statement underscores the strategic importance of the program.
The trial’s early enrollment is a positive development but remains an early‑stage milestone. Tarsus must demonstrate safety, tolerability, and efficacy before regulatory approval can be pursued. The company’s financial strength, driven by XDEMVY sales, provides a solid foundation to fund ongoing clinical development and potential future commercialization of TP‑05.
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