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Approximately 25 million eye care patients in the U.S. suffer from Demodex blepharitis, an eyelid disease characterized by inflammation, redness, and ocular irritation.1-2Demodex blepharitis is caused by an infestation of Demodex mites, the most common ectoparasite found on humans. When present in small numbers, these tiny arachnids largely go unnoticed. However, when an overgrowth occurs, patients may experience symptoms.

Demodex blepharitis can be confidently diagnosed based on the presence of collarettes — waxy build up composed of mite waste and eggs that are found at the base of a patient’s eyelashes. Collarettes are easily visible during a routine eye exam when an eye doctor asks a patient to look down during a slit lamp exam. Unfortunately, despite the high prevalence of the disease, when this step in the eye exam is missed, the disease can go undiagnosed.

Tarsus Pharmaceuticals Co-Founder, President, and CEO Dr. Bobak Azamian discusses how he and Co-Founder Dr. Michael Ackermann identified a potential treatment for this unmet need and how their unique application is being evaluated in other significant disease areas with limited therapeutic options.

Q: You co-founded Tarsus six years ago with an interesting idea ­and novel approach to drug development — take us through the history.

A: My long-time colleague and friend, Michael Ackermann, and I both have a passion for solving complex disease problems in areas where there are significant needs by targeting the root causes. Our idea to target Demodex blepharitis was born from the realization that this highly prevalent eyelid disease had been around for decades without any effective or safe treatment options. Patients were in need, and current management options were lacking. Furthermore, no one in the eye care industry was developing, in our view, any definitive solutions for this huge medical problem. This is where we saw a significant opportunity. We began researching Demodex and exploring options outside of what had been utilized previously, which were primarily lid-hygiene-based management options that essentially put a band-aid over the problem without actually resolving the disease. We knew that in order to resolve the disease, we had to target the root cause — which in this case, was the mite itself.

We did extensive research and looked at several approaches and different molecules. In our research, we saw great potential in lotilaner, a widely used veterinary anti-parasitic drug typically used in animals to kill fleas and ticks — and also Demodex mites, which cause mange. The science behind lotilaner was sound and was specifically designed to target the parasite itself. We applied our research and knowledge and went to great lengths to develop a novel, innovative formulation of the molecule for use in humans, learning that it had a very favorable mite-killing profile.

To date, we’ve completed two pivotal trials collectively involving more than 800 patients with our investigational therapeutic, TP-03 (lotilaner ophthalmic solution, 0.25%). In both studies, TP-03 met the primary and all secondary endpoints with statistical significance and was well-tolerated. With this data, in November 2022 we announced that the U.S. Food and Drug Administration (FDA) accepted our New Drug Application for TP-03 for the treatment of Demodex blepharitis with a Prescription Drug User Fee Act target action date of August 25, 2023.

We’re also investigating the potential of TP-03 to treat another prevalent eye condition with no FDA-approved pharmacologic therapies, meibomian gland disease (MGD). Evidence suggests that Demodex contributes to MGD, and we recently initiated a Phase 2a clinical trial studying TP-03 for the treatment of MGD in patients with Demodex mites.

Q: Beyond eye care, what other disease areas is Tarsus exploring?

A: Lotilaner is currently the platform for Tarsus, and we see so much potential in its application across different diseases. Given the initial success we’ve seen in eye care, we’ve broadened the use of this molecule in other diseases where targeting parasites could make a difference, including Lyme disease prevention and rosacea.

Our strategy to pursue a clinical program in Lyme disease prevention was aligned with our rationale behind studying Demodex blepharitis. Lyme disease is a significant problem with increasing prevalence, and it has limited treatment options. Lyme is the most common vector-born illness in the U.S., estimated to impact 300,000-400,000 people annually.3-4 The disease can cause rash, fever, headache, and fatigue and for some — if left untreated — can result in permanent, debilitating damage, including chronic arthritis, neurological issues, and cognitive defects like impaired memory.5 We believe that targeting the vector that carries the bacteria that causes Lyme — the tick itself ­— is a potentially effective way to prevent individuals from contracting the disease altogether. Our investigational oral therapy, TP-05, is designed to kill the tick before it transmits the disease.

In dermatology, there is evidence supporting a high prevalence of Demodex mites in the skin of patients with rosacea, a chronic skin disease characterized by facial redness, inflammatory lesions, as well as burning and stinging. We are also exploring clinical applications of lotilaner in this area.

Q: You’re not the first company to utilize a molecule from veterinary medicine. What is unique about Tarsus’ approach and why is the company positioned for success?

A: Tarsus was founded with the vision to impact as many patients as possible using an entirely different approach. Our goal was never to just treat a specific disease, it was to target the underlying biology of the disease — the root cause — and focus efforts there. The more we uncover about these parasites and how they contribute to or cause certain diseases, the more therapeutic opportunities we will continue to find, paving a long road of clinical development areas for us.

Q: What’s next for Tarsus?

A: We are committed to becoming a leading pharmaceutical company in eye care, and we believe we have an opportunity to lead in this category based on the significant potential to bring to market a new drug for Demodex blepharitis and the invaluable experience of our incredible leadership team. We are a diverse company that thrives on innovative thinking, and we have a dynamic team that brings remarkable contributions and ideas to the table each day. We’re open to exploring any opportunity that we feel we can make the biggest impact to patients with unmet needs. It’s the responsibility of the entire pharmaceutical and biotechnology industry to make progress that helps individuals not only live longer, but live better, and there are few things as important to us as our eye health.

Explore more on Tarsus’ work in eye care and beyond here.


1. Trattler W, Karpecki P, Rapoport Y, et al. The prevalence of Demodexblepharitis in US eye care clinic patients as determined by collarettes: a pathognomonic sign. Clin Ophthalmol. 2022;16:1153-1164.
2. Saydah SH, Gerzoff RB, Saaddine JB, Zhang X, Cotch MF. Eye care among US adults at high risk for vision loss in the United States in 2002 and 2017. JAMA Ophthalmol.2020;138(5):479-489.
3. Tarsus Pharmaceuticals, Inc. initiates phase 1 Callisto trial of TP-05, a novel, oral, non-vaccine therapeutic for the prevention of Lyme disease. Tarsus Pharmaceuticals, Inc. Press release. June 16, 2021.
4. How many people get Lyme disease? US Centers for Disease Control and Prevention. Accessed July 6, 2021.
5. Signs and symptoms of untreated Lyme disease. US Centers for Disease Control and Prevention. Accessed July 6, 2021.