Protara Therapeutics, Inc. (TARA) May 19, 2026 Investor Update Transcript

Good afternoon, everyone. My name is Jim, and I will be your conference operator today. At this time, I would like to welcome everyone to the Protara Therapeutics Lymphatic Malformations KOL webinar. All lines have been placed on a mute to prevent any background noise, and please note that all questions for the Q&A discussion at the end should be entered into the chat box in the bottom left of our screen. And now, for opening remarks and introductions, I am pleased to turn the floor to our host, Senior Vice President of Investor Relations, Justine O'Malley.

Welcome. ...need in this rare disease, and we believe the chief R&D officer at Protara, who will walk us through an overview of Tara002 as a potential treatment for L.A. ...to have Starborne 1 investigators Dr. Naeem Nasiri and Jesse Jones here to provide their perspective that the two may fit into the treatment armamentarium. Dr. Nassiri is a board-certified vascular and endovascular surgeon of the Yale School of Medicine and Yale New Haven Hospital. A national radiologist, a review of the LM's market, and our views on commercialization. Lower left-hand corner, developing transformative therapies for the treatment of cancer and rare diseases. Our lead asset is Tara002, a genetically distinct strain of streptococcus and immunologic identification and attack of cells that carry mutational burden. We are studying OO2 in non-muscle invasive bladder cancer, or NMIBC, where we recently announced positive data at the American Urology, and we will focus on TAR002 in LM. In addition, we have a program in patients dependent on parental support, where we are studying IV choline chloride, an investigational phospholipid substrate replacement therapy, and an ongoing registrational phase 3 trial. While the focus of today's call will be exclusively on LNs, we remain excited about all three of our pivotal programs and look forward to sharing additional milestones across the portfolio throughout the next 12 months. An investigational genetically distinct strain of strep pyogenes that invite an enormous amount of clinical data from its predecessor compound, OK432, which is approved and marketed under the brand name Pacivanil in Japan by Chugai Pharmaceuticals, where it has been the standard of care and lymphatic malformations, and is now in development by Protara using modern manufacturing techniques, and option in LMs, is reflected in the multiple regulatory designations granted by the FDA, including rare pediatric disease designation, orphan drug designation, breakthrough therapy, and fast-track designations for a priority review voucher, or PRV, upon approval. We expect to complete enrollment of our pivotal STAR-1 trial and intend to submit a BLA based on these data and has potential use beyond LMS, historical literature, other maxillofacial system opportunity for OMS. We announced last week we've had productive, ongoing dialogue with the FDA on our LMS program. We received confirmation that the review of OO2 in LMS has been moved from the Office of Vaccines Research and Review to the Office of Therapeutic Products, or OTP. OTP is a division that has significant experience in pediatric rare diseases. It is also the review division for OO2 and NMIBC. We have not requested an additional pivotal study and have confirmed that our non-clinical package is complete and that no additional reactogenicity or immunogenicity study FDA on the path to registration for OO2 and LNs. And look forward to submitting a BLA. I will now turn the call over to Dr. Nassiri to talk about lymphatic malformations and the unmet need that drives immunologic attack of cells with mutational burden has the potential

to shift the treatment paradigm in LN. Now, moving on to the mechanism of action of 002 in LN. The following aspiration of flu, 002 is administered directly in the cyst, are activated, and NK cells and T lymphocytes are rapidly recruited, which attack and destroy the mutated cells. This increases epithelial permeability, which allows remodeling of vessels to support normal drainage, leading to the eventual depletion. Fibrotic cytokines promote this tissue remodeling and the formation of mature tissue to prevent. In Japan, our data, it promotes long-term resolution. CAR-002 is a targeted approach that attacks mutated cells using the body's own immune system and promotes tissue remodeling to prevent. It has a strong safety and tolerability profile with minimal pain and discomfort to a pediatric patient. We believe this immune-mediated MOA conveys advantages to treating LM's with TARA 002, especially compared to off-label intrasyptic ablative agents. We aligned with the FDA on our clinical program, including the design of STARBORN1 trial, which is a pivotal Phase II prospective baseline-controlled single-arm clinical trial, which is evaluating the safety and efficacy of TAR-002 for the treatment of macrocystic and miscystic LMs in 29 participants aged 6 months to less than 18 years. The trial has two stages. The first is an age de-escalation safety lead-in with three cohorts. The first cohort included children 6 to less than 18 years. The second included children 2 years to less than 6 years. And the final, which we are actively enrolling, includes the youngest cohort of 6 months to less than 2 years. The second stage of the study includes the expansion cohort of patients across these ages. We are actively enrolling patients in the expansion cohort as well. In the trial, patients receive up to four injections of TAR-002 spaced approximately six weeks apart. The primary endpoint of the trial is the proportion of participants with macrocystic and mixed cystic LNs who demonstrate clinical success, which is defined as having either a complete response, 90-100% reduction from baseline in total LN volume, or a substantial response, 60% to less than 90% reduction in total LN volume. Now, I'd like to walk you through the interim results from Starborn 1 that we are presenting at the ISFA World Conference. The analysis includes 16 patients as of the April 10, 2026 data cutoff. 83% of participants that completed treatment achieved clinical success. Of the participants who are assessed at the 8-week post-treatment time point, 100% of the evaluable participants achieved clinical success. In 80% of these patients, clinical success is achieved with one or two doses of TAR002. Looking at evaluable patients, it is clear that TAR002 demonstrates a clinically meaningful response in macro-dominant disease. As is often the case in rare disease, differential diagnosis was made in two evaluable patients in the trial. These patients were initially diagnosed with macrocystic disease, but subsequently confirmed to be ranulous. Consistent with previous understanding of the MOA of TAR002, one participant achieved a complete response and one participant achieved a substantial response. This speaks to the potential of 002 as a possible option for other types of maxillofacial cysts. Moving on to durability of effect of TAR002. Of the seven participants who have reached the 32-week post-treatment assessment, all patients remain disease-free. The durable effect seen in these patients speaks to the robust effect of TAR-002. This is medical photography from three patients treated with TAR-002. All of these patients achieved a complete response. As you can see from the photo, 002's effect is prominent across varying sizes of macro dominant cysts. The patient on the left had a 1.7 liter cyst at baseline. The patient on the right had a 28 ml cyst at baseline. As you can see, in both patients, the resolution of the cyst was dramatic, and the skin remains healthy. Moving on to safety. The majority of adverse events were mild to moderate, with no serious adverse events reported. The majority of AEs were grade 1 or 2, and the most common were swelling and fatigue, and most were transient and resolved within a few days. I'll now turn it over to Dr. Jones to give a summary of his experience as an investigator in the trial.

Thank you, Jackie, Associate Professor at UCLA in Los Angeles. And as you can see, we've had remarkable safety and efficacy over the course of the trial thus far. When patients come to see me in the Vastronomaly's clinic, which is a tertiary referral center, they're looking for an effective treatment. Pathetic malformations, we can't always offer that.

This represents a major...

When CARA came to us with the clinical trial, CARA-002 is a compound built upon a strong track record of OK-432 and has a vast experience in Asia, including Japan and Korea. It has been unavailable in the U.S. for decades. I'm excited about the prospect of bringing this key treatment back into our inventory. The 21 trial offers the unique opportunity to rigorously study sclerotherapy, a disease that has previously been steeped in anecdotes and case reports. The data will enable physicians incorporating the principles of evidence.

I'll share with you a couple of my patients on my specialty.

My affirmation of the peritracheal region in the neck, as evidenced by the arrow here. It also was affected by cystic fibrosis, which is a genetic condition affecting primarily of the lung, resulting in frequent upper respiratory tract infections, which exacerbates lymphatic malformations, leading to multiple episodes of respiratory distress, including intubation. I and my partners treated this patient multiple times, as you can see here, a large variety of existing sclerotherapy options. These include medications such as doxycycline, sotradacol, and eventually ethanol. As you've heard earlier, when physicians reach for ethanol, you know they've reached the end of the road in terms of disclosure. Unfortunately, none of these agents proved successful, and the lymphatic malformation occurred yet again. Luckily for this patient, to engage in expedited access use of Terra002 and this young boy, The help of their administrative staff and our IRB were able to secure this drug and treat this patient outside of the treatment agent were injected for star-borne protocol. Following just one treatment, he had a remarkable response. At all of two months later, there was no visible evidence of a residual malformation. We performed an ultrasound in the clinic setting. While there were no other residuals, the blood was squirming about a bit, as most kids do. Regardless, his result was so powerful there was no need for any additional treatment.

He suffered no adverse events and has been discharged from our care. There's a girl, a 7-year-old female, with a large cystic malformation about her chin.

She also was treated multiple times with a presumed diagnosis of lymphatic malformation. Over the course of her treatment, which included fluid analysis in the laboratory setting, Her diagnosis changed, as described previously, from out of a lymphatic malformation to a ranula, which is the growth of the submandibular gland that secretes a viscous fluid. She, like the other boy, underwent multiple treatments of the usual agents that we have. So to death call, she didn't have to be in the window of the STARBAR-1 trial and was in the room. Of course, the four treatments of TAR-002, her malformation decreased, as you can see here in the table. At the end of the fourth treatment, you can see her malformation is drastically reduced in size, to the point where it is barely palpable and not visible on external examination. The patient and our family were quite pleased with this result. At this point, we stopped further treatment. I think it shows how, in this case, a ranula may be amenable to TARA002. We look forward to continuing enrolling patients in Starborn 1, but also exploring the expanded use of TARA002 for other indications in the future.

I'd be happy to take questions at the end of this.

There are clinical evidence of TARA002's effectiveness, But they also make us think about how patients and caregivers must feel as they deal with the challenges of living with or caring for a child, knowing that there are no FDA-approved treatments for macrocystic lymphatic malformations. It's a potential to become the first and only FDA-approved treatment for patients with macrocystic lymphatic malformations, which makes it an exciting time for us at Protara. Our target indication and mixed cystic lymphatic malformations and published literature on lymphatic malformations. Approximately 1,500 patients are diagnosed with lymphatic malformations each year, and there are up to 80,000 patients currently living with lymphatic malformations. We believe that 20,000 of those patients have macrocystic or mixed cystic. This makes it an attractive total addressable market opportunity in which we believe is greater than a billion dollars. 90% of patients with LMs are diagnosed in the community at an academic medical center with a children's hospital or vascular anomaly center. Two primary treatment options for patients with macrocystic component to their LM are a multidisciplinary team to evaluate and treat stationary teams at vascular anomaly centers are increasingly preferring sclerosis. We believe in managing their lymphatic malformations. Macrocystic LM's fatigue malformations, high recurrence rates associated with surgery are well documented. We currently utilize sclerosis with a lack of consensus dose provider preference and significant opportunity to improve upon patient outcomes and patient treatment experience when compared to other options by using Tara002. Because it is a targeted therapy that leverages a patient's immune system to eliminate the cysts, date on Tara002 compares favorably treatment options, rated 100% clinical success in a valuable patient's to date, and no patient experience recurrence of 32 weeks. We believe that current Tara002 clinical profile to date will enable it to garner orphan drug pricing. The most important reasons to note for this are the disease incidence, the product's high clinical success rate, the durability of response observed with limited numbers of doses, and Tara002 treatment being administered in the ambulatory setting. To date, the majority of patients treated with Tara002 experience clinical success with one or two doses. For treatment for macrocystic lymphatic malformations, we are excited to bring a new treatment option that can help standardize the way in which macrocystic lymphatic malformation patients are treated. Potential launch of tarot, commercial launch, support networks. We see that up to 80% of lymphatic malformation sclerotherapy claims come from a limited number of centers. We are confident that we can achieve commercial success with a relatively modest-sized commercial organization. And we are excited to begin the commercial infrastructure build as we eye a BLA filing in 2H-2027. Now I would like to turn the call back over to our CEO, Jesse Shefferman.

Drive today represents an important illustration and a look beyond our pivotal study in LMS observed in the ranula patient and further potential area to explore the use of OO2. This is based on OK432's history profile in the opportunity, and we look forward to sharing more about this as we solidify the opportunity in LMS and move closer to filing. So, to summarize, we are very pleased with these initial data and OO2's potential to address a significant unmet need in macro and mixed cystic patients. With no FDA-approved therapies, existing off-label treatments presenting unfavorable side effects and surgery oftentimes leading to recurrence, there is a significant therapeutic white space in LTAR002 has the potential to go to R32 in Japan and to submit a BLA to the FDA based on the results of Starbuck investigators or employees, and Justine will now take Q&A from the chat box.

From a durability perspective, what we've seen is that all patients who have reached that time point have maintained their durability, and it's consistent with what we know from OK432 in terms of duration, and we even know from OK432 that the duration is even longer. In those studies, we had followed about to nine years with durable responses.

Given the data that you have seen on some of the existing flare therapies that are used on the label.

When I first started enrolling in STARBAR1, I was a little concerned because some of the patients who were coming to me had failed multiple treatments previously, and I didn't want to enroll a patient and have them fail and make the trial look bad. To my surprise, the drug's been a very effective therapy, so for that reason, it's actually become my go-to treatment.

We have factoring improvements. You know, when the drug was approved in Japan several decades ago, the way that these drugs were controlled and released and just how they were actually formulated, very different than the way that we do it today. So we modernized it in a way that gave us much more control, which then allows us to have a much more predictable safety and efficacy profile.

Along with it, you use STS, you're going to have hemoglobin area, you have terosamylation

over a liter, they can all be treated, as you saw.

There are speculation that have gone to OTP and failed, as many as there are that have gone and won. Our programs are now being reviewed under the same roof. We know that when it has to be formally updated by the OTP perspective, it's a learning curve and an upward slow take on this program really quickly. We get responses back, positive, significant delay, or what Palvella is at the moment to ask ourselves, profile, is there something about OO2, is there something about the modernization of our manufacturing process that is, we'll continue to watch that.

I'll start by saying there's a lot of enthusiasm across our sites, and we are bringing on new sites just based on interest in the trial. The pediatric vulnerable populations, it's always slow and steady in the beginning. As you generate data, it gives more confidence to investigators, as Dr. Jones said, he was a little skeptical about putting patients in. As you generate data and you show a safety and efficacy profile like this, I think that both investigators in the room, our HDS collation cohorts were definitely challenging. We started with a population that was 6 to 17 years old. That's a difficult set of patients to bring into a trial. And you're 16 years old, you've been living with it, your urgency to treat it is low. It took us a while to get through that, but now that we're through it, But, you know, I think our sweet spot is definitely in the 2 to, like, 10-year-old range. It's where we're seeing a majority of patients coming in. But, you know, I think we're on track to enroll the study by the end of the year.

I think also, just to jump in, and I'm going to ask Dr. Jones to kind of, you know, weigh in on this.

You know, I really am excited to see high-quality data come out because that's what's been lacking for 40 years, and they are requiring a lot. The FDA is requiring a lot, and MRI is part of that. The upside is I think it's going to show, without a doubt, if she can get in the trial. I think it's kind of picking up steam in the sense of what's going on and the results.

Dr. Jones, why do you think the patients that you treated when they failed?

Previously, from the previous presentation with my colleague, you know, the other sclerotherapies are all similar in the sense that they try to irritate of either desiccation, like dehydrating it, or denaturing it. TAR-O2 works differently. It incites being unique is what differentiated the treatment.

We're pretty confident that it will be the whole range of ages that we've enrolled in the study. Again, given the breakthrough therapy designation, and I'm hearing that O2 is fairly confident that when it comes down to it, the label will reflect the macro-dominant.

Ladies and gentlemen, this does conclude today's session, and we thank you all for your participation. You may now disconnect your lines and have a good day.