Protara Therapeutics Announces Completion of First Cohort in Phase 2 STARBORN-1 Trial of TARA-002 in Pediatric Patients With Lymphatic Malformations

Protara Therapeutics, Inc. recently announced completion of the first cohort of the Phase 2 STARBORN-1 trial evaluating TARA-002, an investigational cell-based immunopotentiator, for the treatment of pediatric patients with lymphatic malformations (LMs). Enrollment is now underway in additional cohorts.

“The initial data is compelling and reflective of the significant benefit observed in previous studies with OK-432, the predecessor of TARA-002,” said Nancy Bauman, MD, Children’s National Medical Center: Children’s Research Institute, Washington DC, and investigator for the STARBORN-1 trial. “There is a pressing need for an effective therapeutic option for LMs, a rare condition mainly affecting children for which there are currently no U.S. FDA approved agents. I remain excited about the potential for TARA-002 to play a meaningful role in the treatment of these patients and look forward to future learnings from this important study.”

Of three patients treated in the first cohort, which enrolled individuals six years to less than 18 years of age, two patients treated with TARA-002 achieved a complete response after receiving one dose of TARA-002; the responses were seen in a patient with a macrocystic lymphatic malformation and a patient with a ranula. The safety and tolerability seen in this cohort was consistent with that of the historical experience with OK-432 and included treatment emergent adverse events (TEAEs) of pain, swelling, fatigue, and body temperature increases. All TEAEs were mild to moderate and resolved.

“We are pleased with the progress of our Phase 2 STARBORN-1 trial and the encouraging results we have seen thus far,” said Jesse Shefferman, Chief Executive Officer of Protara Therapeutics. “We have received positive feedback from our investigators and already have a number of patients on waiting lists for our subsequent cohorts, and expect to share initial results from our next cohort in the first half of 2025.”

STARBORN-1 is a Phase 2 single-arm, open-label, prospective clinical trial evaluating the safety and efficacy of intracystic injection of TARA-002 for the treatment of macrocystic and mixed cystic LMs (≥ 50% macrocystic disease) in participants six months to less than 18 years of age. The trial will enroll approximately 30 patients including age de-escalation safety lead-in cohorts of children ages 6 years to less than 18 years, 2 years to less than 6 years, and 6 months to less than 2 years, who will receive up to four injections of TARA-002 spaced approximately six weeks apart.

The primary endpoint of the trial is the proportion of participants with macrocystic and mixed cystic LMs who demonstrate clinical success, defined as having either a complete response (90% to 100% reduction from baseline in total LM volume) or substantial response (60% to less than 90% reduction in total LM volume) as measured by axial imaging.

TARA-002 is an investigational cell therapy based on the broad immunopotentiator, OK-432, which was originally granted marketing approval by the Japanese Ministry of Health and Welfare as an immunopotentiating cancer therapeutic agent. This cell therapy is currently approved in Japan and Taiwan for LMs and has been used to successfully treat thousands of pediatric patients with this rare condition. In addition, OK-432 was studied in the largest ever conducted Phase 2 trials in LMs, in which the therapy was administered via a now-closed compassionate use program led by the University of Iowa.

TARA-002 has been granted Rare Pediatric Disease designation by the U.S. Food and Drug Administration (FDA) for the treatment of LMs.

Lymphatic malformations (LMs) are rare, congenital malformations of lymphatic vessels resulting in the failure of these structures to connect or drain into the venous system. Most LMs are present in the head and neck region and are diagnosed in early childhood during the period of active lymphatic growth, with more than 50% detected at birth and 90% diagnosed before the age of three years. The most common morbidities and serious manifestations of the disease include compression of the upper aerodigestive tract, including airway obstruction requiring intubation and possible tracheostomy dependence; intralesional bleeding; impingement on critical structures, including nerves, vessels, lymphatics; recurrent infection; and cosmetic and other functional disabilities.

Protara is committed to advancing transformative therapies for people with cancer and rare diseases. Protara’s portfolio includes its lead program, TARA-002, an investigational cell-based therapy being developed for the treatment of non-muscle invasive bladder cancer and lymphatic malformations, and IV Choline Chloride, an investigational phospholipid substrate replacement for patients dependent on parenteral support. For more information, visit www.protaratx.com.