- Tectonic Therapeutic, Inc. (TECX) announced **positive topline results from its Phase 1b Part B clinical trial for TX45** in patients with Group 2 Pulmonary Hypertension in Heart Failure with reduced Ejection Fraction (PH-HFrEF) on **October 29, 2025**.  **[1681087_0001193125-25-256958_d30823dex992.htm:0]** 
- A single intravenous dose of TX45 was **well tolerated**, showing **no serious or severe adverse events**.  **[1681087_0001193125-25-256958_d30823dex992.htm:0]** **[1681087_0001193125-25-256958_d30823dex992.htm:1]** 
- The trial demonstrated **meaningful improvements in both left heart function and pulmonary hemodynamics**, with a **29.2% decrease in Pulmonary Capillary Wedge Pressure (PCWP)** and a **17.3% increase in Cardiac Output (CO)**.  **[1681087_0001193125-25-256958_d30823dex992.htm:0]** **[1681087_0001193125-25-256958_d30823dex992.htm:1]** **[1681087_0001193125-25-256958_d30823dex991.htm:3]** 
- Echocardiography data at Day 29 indicated **persistent improvements**, including a **19.4% increase in Left Ventricular Ejection Fraction (LVEF)** and a **20.3% improvement in Right Ventricular Fractional Area of Change (RVFAC)**.  **[1681087_0001193125-25-256958_d30823dex992.htm:1]**  
- These findings support the **potential expansion of TX45's addressable patient population** to PH-HFrEF, with topline results from the ongoing APEX Phase 2 clinical trial expected in **2026**.  **[1681087_0001193125-25-256958_d30823dex992.htm:0]**

Tectonic Therapeutic Announces Positive Phase 1b Part B Clinical Trial Data for TX45

- TECX announced positive top-line results from Part B of its Phase 1B clinical trial for **TX45** in patients with pulmonary hypertension associated with reduced ejection fraction heart failure (PHFREF), demonstrating **safety and significant improvements in hemodynamic measurements**.  **[0001681087_2213096_0]** **[0001681087_2213096_3]** **[0001681087_2213096_4]** 
- Key hemodynamic improvements observed included a **29% decrease in pulmonary capillary wedge pressure**, a **20% reduction in pulmonary vascular resistance (PVR)** in the PVR ≥ 3 WU population, and a **17% increase in cardiac output**.  **[0001681087_2213096_3]** 
- Echocardiographic data suggested **sustained improvements** in markers of left ventricular function, pulmonary hemodynamics, and right ventricular function up to **29 days post-dose** after a single dose of TX45.  **[0001681087_2213096_3]** 
- The APEX Phase 2 clinical trial for TX45 is **over 50% enrolled**, with recruitment now limited to patients with **PVR ≥ 3 WU**; TECX plans to update and narrow guidance for the top-line readout by the **end of Q1 2026**.  **[0001681087_2213096_5]** 
- The company has a financial runway extending into the **fourth quarter of 2028** and plans to initiate a study for TX45 in pulmonary hypertension associated with interstitial lung disease (PHILD) in 2026, while its TX2100 program for hereditary hemorrhagic telangiectasia remains on track to enter the clinic in **Q1 2026**.  **[0001681087_2213096_5]**

TECX Reports Positive Phase 1B Part B Results for TX45 in PHFREF and Provides APEX Trial Update

- **TECX** announced **positive results** from its **TX45 Phase 1b (Part B) single-dose hemodynamic trial** in patients with PH-HFrEF (Pulmonary Hypertension with Heart Failure with Reduced Ejection Fraction) in October 2025.  **[0001681087_2213011:0]** **[0001681087_2213011:4]** 
- The study observed that **TX45 was well tolerated** and demonstrated **improvements in left ventricular function and pulmonary hemodynamics** in PH-HFrEF patients, consistent with effects seen in a prior PH-HFpEF study.  **[0001681087_2213011:4]** **[0001681087_2213011:21]** 
- Key hemodynamic improvements included a **-29.2% reduction in PCWP** (pulmonary capillary wedge pressure) and a **+17.3% increase in cardiac output (CO)** across all participants (n=14).  **[0001681087_2213011:19]** 
- Echocardiographic results at Day 29 showed **sustained improvements** in markers of left ventricular and right ventricular function, including a **+19.4% increase in LVEF** (left ventricular ejection fraction).  **[0001681087_2213011:20]** **[0001681087_2213011:21]** 
- These results **support further clinical investigation** of TX45 in PH-HFrEF, potentially expanding its market opportunity, pending data from the ongoing APEX Phase 2 clinical trial.  **[0001681087_2213011:4]** **[0001681087_2213011:21]**

Tectonic Therapeutic (TECX)