Tarsus Doses First Participant in 700-Subject Phase 2 Lyme Prevention Trial
Tarsus Pharmaceuticals has dosed the first participant in its Phase 2 Calliope trial of TP-05, enrolling roughly 700 adults to evaluate safety, tolerability and pharmacokinetics. Enrollment is slated to complete during the 2026 tick season with topline results expected in H1 2027 after Phase 2a data showed over 90% tick kill.
1. Trial Launch and Design
Tarsus has commenced its Phase 2 Calliope trial by dosing the first participant with TP-05, a novel oral prophylactic intended to kill Lyme-infected ticks before disease transmission. This randomized, double-blind, placebo-controlled study will enroll approximately 700 healthy adults at risk for Lyme disease to assess safety, tolerability and pharmacokinetics.
2. Prior Phase 2a Proof-of-Concept
In the preceding Phase 2a Carpo trial, a single dose of TP-05 achieved over 90% tick mortality within 24 hours of attachment compared to 5% with placebo (p<0.001), demonstrating durable efficacy at both Day 1 and Day 30 alongside a favorable tolerability profile.
3. Enrollment Timeline and Expectations
Tarsus plans to complete enrollment during the 2026 tick season and expects topline results in the first half of 2027. These data will inform potential advancement toward regulatory discussions for what could become the first FDA-approved pharmacological prophylactic option for Lyme disease prevention.