Protara Therapeutics Inc reported updated interim findings from its Phase 2 ADVANCED-2 study of TARA-002 in patients with high-risk Non-Muscle Invasive Bladder Cancer, prompting a sharp drop in the company’s shares in after-hours trading. The company said its stock fell 19% in after-hours trade on Monday following the data release.
The company disclosed results from two cohorts within the trial. In the BCG-Unresponsive group, 35 participants were evaluable and produced a complete response rate of 68.2% at six months and 33.3% at 12 months. In the BCG-Naïve cohort, 29 participants were evaluable and showed a complete response rate of 66.7% at six months and 57.9% at 12 months. The company noted the data cutoff for the report was January 28, 2026.
TARA-002 is described by the company as an investigational cell-based therapy delivered intravesically and is being studied in patients with carcinoma in situ who are either BCG-Unresponsive or BCG-Naïve. Protara highlighted safety observations from the interim dataset, reporting no treatment-related adverse events at Grade 3 or greater and no related serious adverse events across the cohorts. The most commonly observed treatment-related events were dysuria, bladder spasm, fatigue and micturition urgency, with most bladder irritation events resolving within hours to days.
Among responders in the BCG-Unresponsive cohort, the Kaplan-Meier estimate for maintaining a complete response for six months stood at 71.1%. The company also reported that all five patients who sustained responses through the nine- to 12-month window continued to demonstrate complete responses at their most recent assessments.
On trial execution, Protara said it expects to complete enrollment of the BCG-Unresponsive registrational cohort in the second half of 2026. Enrollment is already complete in the BCG-Naïve cohort, which the company reported includes 31 patients. The company plans to initiate ADVANCED-3, a registrational trial in BCG-Naïve patients, in the second half of 2026.
Protara indicated it will present the updated ADVANCED-2 results on Friday at the American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco.
Summary
Interim Phase 2 results for TARA-002 showed complete response rates at defined follow-up intervals in both BCG-Unresponsive and BCG-Naïve cohorts, with a favorable short-term safety profile. The company outlined timelines for completing registrational cohort enrollment and starting a new registrational trial, and will present the data at an upcoming oncology symposium.
Key points
- Shares of Protara fell 19% in after-hours trading after the company released interim ADVANCED-2 data.
- TARA-002 produced complete response rates of 68.2% (six months) and 33.3% (12 months) in 35 evaluable BCG-Unresponsive patients; in 29 evaluable BCG-Naïve patients, rates were 66.7% (six months) and 57.9% (12 months).
- Safety signals were positive in the interim dataset - no Grade 3 or greater treatment-related adverse events or related serious adverse events were reported; common events included dysuria, bladder spasm, fatigue and urgency.
Risks and uncertainties
- Interim data represent a snapshot as of the January 28, 2026 cutoff and may change with longer follow-up or larger evaluable populations - this influences investor reaction and regulatory evaluation.
- Protara expects to complete enrollment of the BCG-Unresponsive registrational cohort in the second half of 2026, which is a future milestone and therefore subject to timing uncertainty.
- While short-term safety showed no high-grade treatment-related events, the current report does not provide longer-term safety or durability beyond the reported follow-up windows.