Protara Therapeutics Highlights TARA-002 NMIBC Data, FDA Plans for Lymphatic Malformations at Oppenheimer Conf

Key Points

• TARA‑002: ADVANCED‑2 interim data reported a 68% complete response rate at six months (n=22) and 33% at 12 months (n=15), which management attributes to small‑sample volatility and expects to rise toward ~40% as the study enrolls to a planned 100 patients; the company is pursuing ADVANCED‑3, a front‑line randomized trial intended to position TARA‑002 as an alternative when BCG is unavailable or inappropriate.
• STARBORN‑1 (lymphatic malformations): Enrollment is ongoing and Protara has scheduled an FDA meeting to define a registrational path, estimating an addressable population of about 1,000–1,200 incident patients per year and planning separate dosing, branding, and channels from the NMIBC program.
• IV choline chloride: Targeting chronic TPN patients (~35,000 U.S. patients), the THRIVE‑1 observational data showed ~80% choline deficiency and ~68% with liver injury; Protara plans PK and liver‑function endpoints and holds an Orange Book‑listed patent extending to 2041.

Protara Therapeutics NASDAQ: TARA executives outlined progress across the company’s two clinical-stage programs during a fireside chat at Oppenheimer’s 36th Annual Healthcare Life Sciences Conference, highlighting updated interim results from its ongoing non-muscle invasive bladder cancer (NMIBC) study of TARA-002 and providing an update on regulatory planning in lymphatic malformations (LMs). The company also discussed its intravenous (IV) choline chloride program for patients receiving long-term parenteral nutrition.

TARA-002: inactivated bacterial immunopotentiator

CEO Jesse Shefferman described TARA-002 as a whole-cell bacterial therapeutic derived from a genetically distinct strain of Streptococcus pyogenes that is fully inactivated through manufacturing while retaining antigens intended to stimulate the immune system. He said the product, known as OK-432 in Japan, has been marketed there for decades and is the standard of care for macrocystic and mixed lymphatic malformations. He also noted that OK-432 has labels in Japan for use adjunctively with chemotherapy in certain cancers (head, neck, thyroid, gastric, and lung), and characterized it as potentially an early immuno-oncology agent.

Shefferman emphasized that Protara is developing TARA-002 in two late-stage settings:

• NMIBC, including a registrational study in BCG-unresponsive carcinoma in situ (CIS)
• Lymphatic malformations, focusing on macrocystic and mixed lesions in the STARBORN-1 study

ADVANCED-2 interim results and durability discussion

The discussion focused on interim data from ADVANCED-2, Protara’s ongoing study of TARA-002 in BCG-unresponsive NMIBC. Gershell cited the company’s reported interim results: a 68% complete response (CR) rate at six months in 22 patients, and a 33% CR rate at 12 months in 15 evaluable patients. He noted the formal ASCO GU presentation was scheduled for the following day.

Addressing questions about the 12-month figure, Shefferman attributed the lower 12-month landmark CR rate to small numbers and the volatility that can arise early in oncology datasets. He said that, prior to the latest readout, the company had been “well within the mid-40s” in terms of 12-month response rate, but two patients who were pending ultimately were no longer in response, which moved the rate lower.

Shefferman said the dataset represents the first 15 patients of a planned 100-patient study, and stated the company expects the 12-month rate to move back into the 40% range as the sample size grows. He also said Protara has observed that prior BCG exposure has not appeared to be a major driver of response as the six-month response data in BCG-naive and BCG-unresponsive cohorts have become more interpretable.

ADVANCED-3: positioning beyond BCG-unresponsive CIS

Both speakers described BCG-unresponsive CIS as a pathway to registration rather than the company’s largest commercial opportunity. Shefferman said the company’s “big swing” in NMIBC is ADVANCED-3, a planned randomized controlled trial in the front-line setting intended to support use of TARA-002 as an alternative when BCG is unavailable or inappropriate, and potentially in BCG-exposed or inadequately treated patients, a population he said has grown due to BCG shortages.

Shefferman said Protara expects ADVANCED-2 to be fully enrolled “comfortably before the end of 2026,” and characterized completion of that study as a way to establish pharmacy access, reimbursement infrastructure, and presence in urology practices while ADVANCED-3 progresses.

On unmet need, Shefferman said the company presented the FDA with seven years of NMIBC claims data and observed that about 35% of otherwise BCG-eligible patients did not receive BCG. He estimated that group represents roughly 11,000 to 15,000 patients annually based on claims data presented to the agency, citing factors including patient refusal and BCG intolerance. He said the FDA’s acceptance of ADVANCED-3 design was based on comparison to intravesical chemotherapy options (gemcitabine or mitomycin, investigator’s choice). He also described a larger “exposed” population potentially in the tens of thousands annually, for which he said the practical option is chemotherapy.

Shefferman also discussed considerations affecting adoption, including treatment administration time and operational burden in community practices. He contrasted the needs of academic centers and community urologists, and said a consistent supply of TARA-002 could be meaningful for clinicians concerned about the ability to secure a full BCG course over time.

STARBORN-1 lymphatic malformations: enrollment and FDA engagement

On the LM program, Shefferman said the company continues to enroll patients in STARBORN-1 and that additional patients have been dosed and have read out since the interim data release in November. He said Protara has a meeting scheduled with the FDA to discuss a registrational path forward, adding that FDA representatives from multiple disciplines would participate.

When asked about the potential treated population, Shefferman said he believes an addressable opportunity could be on the order of 1,000 to 1,200 patients per year, consisting mainly of incident cases as well as some previously treated patients who became “treatment-apathetic” due to limited prior options.

On potential commercial separation between LM and NMIBC presentations, Shefferman said dosing differs substantially—he described LM administration as 1 KE per dose for up to four doses, versus NMIBC dosing of 40 KE and as many as ~21 vials in the first year—and said the company expects different branding, channels, and coding.

IV choline chloride: long-term parenteral nutrition and IP

Protara also discussed its IV choline chloride program targeting patients on long-term chronic total parenteral nutrition (TPN). Shefferman estimated there are roughly 35,000 such patients in the United States, defining chronic TPN as more than four days per week and more than six months per year.

He cited results from the company’s observational THRIVE-1 study, stating that approximately 80% of patients on parenteral support were choline deficient and that 68% had some form of liver injury. He described choline’s role as a precursor to phosphatidylcholine and linked deficiency to liver function and fat transport, noting that choline-deficient diets across multiple species have been associated with elevated liver function tests within days or weeks.

Shefferman said Protara is pursuing a pharmacokinetic-based endpoint demonstrating increased serum choline following administration, with secondary endpoints evaluating liver function. He also said the company has an Orange Book-listed product claim patent extending to 2041, with related intellectual property being prosecuted in additional geographies.

About Protara Therapeutics NASDAQ: TARA

Protara Therapeutics, Inc is a clinical-stage biopharmaceutical company focused on developing novel immunotherapies for virus-driven cancers. The company's primary areas of research include human papillomavirus (HPV)–associated malignancies, where it seeks to harness and enhance the body's immune response to target tumor cells. Protara's therapeutic strategy combines antigen-specific vaccination approaches with modulators of T-cell activation to improve clinical outcomes in patients with HPV-mediated disease.

Protara's lead immunotherapy candidate is PTX-35, an investigational monoclonal antibody designed to agonize OX40, a co-stimulatory receptor on T cells.

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