Protara Therapeutics Announces Dosing of First Patient in Phase 3 Registrational THRIVE-3 Trial of IV Choline Chloride in Patients on Long-Term Parenteral Support

Rhea-AI Summary

Protara Therapeutics (Nasdaq: TARA) announced dosing of the first patient in the Phase 3 registrational THRIVE-3 trial of IV Choline Chloride for patients on long-term parenteral support (PS).

The investigational therapy has prior FDA Fast Track designation. THRIVE-3 is a seamless Phase 2b/3 design: an 8-week Phase 2b open-label dose-confirmation in 24 patients, followed by ~105 additional patients in a 24-week double-blind, randomized, placebo-controlled Phase 3. The primary endpoint is change in plasma choline concentration versus placebo. An interim analysis is expected in the second half of 2026. The company notes 78% of PS-dependent patients are impacted by choline deficiency and that no IV choline products are currently approved globally.

Positive

• Phase 3 dosing begun with first patient dosed
• FDA Fast Track designation for IV Choline Chloride
• Seamless trial design: 24 patient Phase 2b then ~105 Phase 3 patients
• Interim analysis planned in H2 2026

Negative

• Primary endpoint is plasma choline concentration, a biomarker rather than a direct clinical outcome
• Initial Phase 2b cohort size is 24 patients, a limited sample for dose confirmation

News Market Reaction

+11.13%

36 alerts

+11.13% News Effect

+8.5% Peak in 3 hr 44 min

+$30M Valuation Impact

$303M Market Cap

0.7x Rel. Volume

On the day this news was published, TARA gained 11.13%, reflecting a significant positive market reaction. Argus tracked a peak move of +8.5% during that session. Our momentum scanner triggered 36 alerts that day, indicating elevated trading interest and price volatility. This price movement added approximately $30M to the company's valuation, bringing the market cap to $303M at that time.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

PS patients affected: 78% Phase 2b duration: 8 weeks Phase 2b sample size: 24 patients +5 more

8 metrics

PS patients affected 78% Patients on parenteral support with choline deficiency per article

Phase 2b duration 8 weeks Open-label dose-confirmation part of THRIVE-3

Phase 2b sample size 24 patients Initial open-label portion of THRIVE-3

Phase 3 sample size approximately 105 patients Planned enrollment for randomized Phase 3 portion

Phase 3 duration 24 weeks Double-blinded randomized placebo-controlled part of THRIVE-3

Primary endpoint Change in plasma choline concentration IV Choline Chloride vs placebo in THRIVE-3

Interim analysis timing 2H 2026 Planned interim analysis for THRIVE-3

Price move pre-news -5.01% 24h move ahead of this Phase 3 dosing announcement

Market Reality Check

Price: $6.71 Vol: Volume 1,291,129 is 58% a...

high vol

$6.71 Last Close

Volume Volume 1,291,129 is 58% above the 20-day average of 816,560, indicating elevated trading interest ahead of this update. high

Technical Shares at $5.12 are trading above the 200-day MA of $4.12, despite a -5.01% move over the last 24 hours.

Peers on Argus

TARA fell -5.01% while peers showed mixed moves: EQ down -18.87%, IOBT up 5.69%,...

1 Down

TARA fell -5.01% while peers showed mixed moves: EQ down -18.87%, IOBT up 5.69%, others modestly negative. Momentum scanner only flagged KALA moving down, suggesting a stock-specific reaction.

Historical Context

5 past events · Latest: Jan 05 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Jan 05	Regulatory designations	Positive	+0.2%	FDA Breakthrough Therapy and Fast Track designations for TARA-002 in LMs.
Dec 08	Equity offering close	Neutral	+0.3%	Closing of $75M underwritten offering to fund TARA-002 and other programs.
Dec 04	Offering pricing	Neutral	+0.7%	Pricing of $75M common stock offering at $5.75 per share.
Dec 04	Offering announcement	Neutral	+0.7%	Proposed $75M public offering of common stock and pre-funded warrants.
Dec 03	Clinical data update	Positive	+9.3%	Updated interim ADVANCED-2 data for TARA-002 in BCG-naïve NMIBC.

Pattern Detected

Recent news, including positive clinical and regulatory updates as well as equity offerings, has generally seen aligned and often modestly positive price reactions.

Recent Company History

Over the last two months, Protara has combined clinical progress with balance sheet strengthening. On Dec 3, 2025, positive Phase 2 ADVANCED-2 TARA-002 data in NMIBC coincided with a 9.32% gain. A December underwritten offering of $75 million, later upsized to about $86.3 million gross via option exercise, produced small positive moves, indicating limited immediate dilution pressure in trading. On Jan 5, 2026, new FDA Breakthrough Therapy and Fast Track designations for TARA-002 also aligned with a slight gain. Against that backdrop, today’s negative move on a Phase 3 trial initiation contrasts with the usual positive skew around prior clinical milestones.

Market Pulse Summary

The stock surged +11.1% in the session following this news. A strong positive reaction aligns with P...

Analysis

The stock surged +11.1% in the session following this news. A strong positive reaction aligns with Protara’s history of favorable responses to clinical milestones, such as the 9.32% move on ADVANCED-2 data. However, past equity offerings and ongoing trial costs underline financing and execution risks that could temper sustainability. Investors have previously rewarded robust data, but enthusiasm sometimes faded as dilution and development timelines came into focus, making follow-through dependent on subsequent readouts like the planned THRIVE-3 interim in 2H 2026.

Key Terms

parenteral support, fast track designation, phase 3, open-label, +4 more

8 terms

parenteral support medical

"evaluating intravenous (IV) Choline Chloride in patients receiving long-term parenteral support (PS)"

Parenteral support is medical care that delivers nutrition, fluids or medications directly into a patient’s bloodstream or body tissues, bypassing the digestive system—think of it as feeding or hydrating someone through an IV rather than by mouth. Investors care because this service involves specialized products, durable revenue from long-term patient use, strict safety and reimbursement rules, and potential regulatory or supply risks that affect company earnings and growth.

fast track designation regulatory

"IV Choline Chloride ... was previously granted Fast Track designation by the U.S. Food and Drug Administration"

A "fast track designation" is a process that speeds up the review and approval of a product or project, allowing it to reach the market or be completed more quickly than usual. For investors, it can signal that a product may become available sooner, potentially leading to earlier revenue or benefits, and indicating a priority status that might influence company performance and market opportunities.

phase 3 medical

"Phase 3 registrational THRIVE-3 clinical trial evaluating intravenous (IV) Choline Chloride"

Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.

open-label technical

"Following an 8-week Phase 2b open-label, dose-confirmation trial in 24 patients"

Open-label describes a situation where everyone involved in a study or process knows the full details, such as who is receiving a treatment or intervention. For investors, understanding whether a project or product is open-label helps gauge the level of transparency and potential biases, influencing trust and decision-making. It’s like knowing whether a test or experiment is conducted openly or behind closed doors.

double-blinded technical

"a 24-week Phase 3 double-blinded, randomized, placebo-controlled trial"

A double-blinded study is a test where neither the participants nor the people administering the treatments know who is getting which version, so expectations can't influence the results. For investors, that fairness check makes clinical or product test results more reliable—think of it like a blind taste test where both the taster and server are kept unaware—so positive outcomes from double-blinded studies carry more weight for valuation and regulatory confidence.

randomized, placebo-controlled technical

"24-week Phase 3 double-blinded, randomized, placebo-controlled trial"

A randomized, placebo-controlled trial is a medical study where people are assigned by chance (like flipping a coin) to receive either the experimental treatment or an inactive substitute (a placebo), and neither participants nor often the researchers know who got which. For investors, this design is the gold standard for showing whether a therapy truly works beyond chance or expectation, which reduces uncertainty about regulatory approval, market adoption, and the commercial value of a drug or device.

plasma choline concentration medical

"The primary endpoint of the trial is the change in plasma choline concentration from baseline"

Plasma choline concentration is the measured amount of choline, a nutrient and signaling molecule, circulating in a person’s blood. Investors watch it because changes can serve as a biological signal—like a car’s dashboard light—that a drug, supplement or disease is affecting brain, liver or heart function; those signals can influence clinical trial results, regulatory decisions and market value for companies developing related therapies.

home parenteral nutrition medical

"ESPEN in its Guideline on Home Parenteral Nutrition"

Intravenous feeding delivered in a patient’s home when the digestive system can’t absorb enough nutrients; it supplies fluids, electrolytes and calories through a tube into a vein, like a long-term IV drip that replaces meals. Investors care because it creates ongoing demand for specialized pumps, sterile solutions, delivery services and care management, producing recurring revenue, reimbursement sensitivity and regulatory risk that can affect healthcare company earnings and valuations.

AI-generated analysis. Not financial advice.

NEW YORK, Jan. 07, 2026 (GLOBE NEWSWIRE) -- Protara Therapeutics, Inc. (Nasdaq: TARA), a clinical-stage company developing transformative therapies for the treatment of cancer and rare diseases, today announced that patient dosing is now underway in its Phase 3 registrational THRIVE-3 clinical trial evaluating intravenous (IV) Choline Chloride in patients receiving long-term parenteral support (PS). IV Choline Chloride, the Company’s investigational phospholipid substrate replacement therapy, was previously granted Fast Track designation by the U.S. Food and Drug Administration.

“Choline deficiency, which can lead to serious hepatic injury, neuropsychological impairment, muscle damage, and thrombotic abnormalities, has been shown to impact 78% of patients dependent on PS, yet there are currently no approved IV choline products globally to address this pressing need,” said Jesse Shefferman, Chief Executive Officer of Protara Therapeutics. “We believe that IV Choline Chloride has the potential to make a meaningful impact in this highly underserved population and could ultimately become the first FDA-approved IV choline therapy for patients dependent on PS. We look forward to advancing this important study and expect to provide an interim analysis from the trial in the second half of 2026.”

THRIVE-3 (NCT06910943) is a seamless Phase 2b/3 trial designed to assess the efficacy and safety of low and high dose IV Choline Chloride in adolescent and adult patients receiving long-term PS when oral or enteral nutrition is not possible, insufficient, or contraindicated. Following an 8-week Phase 2b open-label, dose-confirmation trial in 24 patients, approximately 105 additional patients will be enrolled in a 24-week Phase 3 double-blinded, randomized, placebo-controlled trial. The primary endpoint of the trial is the change in plasma choline concentration from baseline compared to placebo. In addition, patients will be eligible to advance to an open-label extension period following completion of each phase of the study.

Choline is an essential quaternary amine that is naturally available in some foods and is widely utilized throughout the human body as an important contributor to many steps of metabolism. It serves as a key methyl donor in multiple metabolic pathways and is abundantly stored as a phospholipid throughout the human body. Patients on PS are unable to synthesize choline from enteral nutrition sources, and there are currently no available PS formulations containing choline. IV choline is recommended for patients receiving PS by the American Society for Parenteral and Enteral Nutrition (ASPEN) in its Recommendations for Changes in Commercially Available Parenteral Multivitamin and Multi–Trace Element Products, as well as by the European Society for Clinical Nutrition and Metabolism (ESPEN) in its Guideline on Home Parenteral Nutrition.

About IV Choline Chloride

IV Choline Chloride is an investigational, intravenous phospholipid substrate replacement therapy in development for patients receiving PS. Choline is a known important substrate for phospholipids that are critical for healthy liver function that also play an important role in modulating gene expression, cell membrane signaling, brain development and neurotransmission, muscle function, and bone health. PS patients are unable to synthesize choline from enteral nutrition sources, and there are currently no available PS formulations containing choline. Seventy-eight percent of patients dependent on PS are choline-deficient and 63% of those have some degree of liver dysfunction, which can lead to hepatic failure. Every year in the U.S. there are approximately 90,000 people who require PS at home and of those approximately 30,000 are on long-term PS. IV Choline Chloride has the potential to become the first U.S. Food and Drug Administration (FDA) approved IV choline formulation for PS patients. It has been granted Orphan Drug Designation by the FDA for the prevention and/or treatment of choline deficiency in patients on long-term PN and has been granted Fast Track Designation as a source of choline when oral or enteral nutrition is not possible, insufficient, or contraindicated. The U.S. Patent and Trademark Office has issued Protara a U.S. patent claiming a choline composition and a U.S. patent claiming a method for treating choline deficiency with a choline composition, each with a term expiring in 2041.

About Protara Therapeutics, Inc.

Protara is a clinical-stage biotechnology company committed to advancing transformative therapies for people with cancer and rare diseases. Protara’s portfolio includes its lead candidate, TARA-002, an investigational cell-based therapy in development for the treatment of non-muscle invasive bladder cancer (NMIBC) and lymphatic malformations (LMs). The Company is evaluating TARA-002 in an ongoing Phase 2 trial in NMIBC patients with carcinoma in situ (CIS) who are unresponsive or naïve to treatment with Bacillus Calmette-Guérin, as well as a Phase 2 trial in pediatric patients with LMs. Additionally, Protara is developing IV Choline Chloride, an investigational phospholipid substrate replacement for patients on parenteral nutrition who are otherwise unable to meet their choline needs via oral or enteral routes. For more information, visit www.protaratx.com.

Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are "forward looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Protara may, in some cases, use terms such as “predicts,” “believes,” “potential,” “proposed,” “continue,” “designed,” “estimates,” “anticipates,” “expects,” “plans,” “intends,” “may,” “could,” “might,” “will,” “should” or other words or expressions referencing future events, conditions or circumstances that convey uncertainty of future events or outcomes to identify these forward-looking statements. Such forward-looking statements include but are not limited to, statements regarding Protara’s intentions, beliefs, projections, outlook, analyses or current expectations concerning, among other things: Protara’s business strategy, including its development plans for its product candidates and plans regarding the timing or outcome of existing or future clinical trials (including the timing of any particular phases of such trials and the timing of the announcement of any data produced during such trials or phases thereof); statements related to expectations regarding interactions with the U.S. Food and Drug Administration (FDA); Protara’s financial position; statements regarding the anticipated safety or efficacy of Protara’s product candidates; and Protara’s outlook for the remainder of the year and future periods. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Factors that contribute to the uncertain nature of the forward-looking statements include: risks that Protara’s financial guidance may not be as expected, as well as risks and uncertainties associated with: Protara’s development programs, including the initiation and completion of non-clinical studies and clinical trials and the timing of required filings with the FDA and other regulatory agencies; general market conditions; changes in the competitive landscape; changes in Protara’s strategic and commercial plans; Protara’s ability to obtain sufficient financing to fund its strategic plans and commercialization efforts; having to use cash in ways or on timing other than expected; the impact of market volatility on cash reserves; failure to attract and retain management and key personnel; the impact of general U.S. and foreign, economic, industry, market, regulatory, political or public health conditions; and the risks and uncertainties associated with Protara’s business and financial condition in general, including the risks and uncertainties described more fully under the caption “Risk Factors” and elsewhere in Protara's filings and reports with the United States Securities and Exchange Commission. All forward-looking statements contained in this press release speak only as of the date on which they were made and are based on management's assumptions and estimates as of such date. Protara undertakes no obligation to update any forward-looking statements, whether as a result of the receipt of new information, the occurrence of future events or otherwise, except as required by law.

Company Contact:

Justine O'Malley
Protara Therapeutics
Justine.OMalley@protaratx.com
646-817-2836

FAQ

What did Protara (TARA) announce about the THRIVE-3 Phase 3 trial on January 7, 2026?

Protara announced dosing of the first patient in the Phase 3 registrational THRIVE-3 trial of IV Choline Chloride for patients on long-term parenteral support.

How is the THRIVE-3 trial for TARA structured and how many patients will be enrolled?

THRIVE-3 is a seamless Phase 2b/3 trial: an 8-week Phase 2b open-label dose-confirmation in 24 patients, followed by ~105 additional patients in a 24-week double-blind Phase 3.

What is the primary endpoint of Protara's (TARA) THRIVE-3 trial?

The primary endpoint is the change in plasma choline concentration from baseline compared to placebo.

When does Protara expect interim results from the THRIVE-3 (TARA) trial?

The company expects to provide an interim analysis from the trial in the second half of 2026.

Does IV Choline Chloride have any special regulatory status for TARA?

IV Choline Chloride was previously granted Fast Track designation by the U.S. Food and Drug Administration.

Are there currently approved IV choline products for patients on parenteral support?

No IV choline products are currently approved globally for patients dependent on long-term parenteral support, according to the announcement.

What proportion of PS-dependent patients does Protara cite as affected by choline deficiency?

The company cites that 78% of patients dependent on parenteral support are impacted by choline deficiency.