Tectonic Therapeutic said its lead candidate TX2100 cleared a first-in-human safety hurdle, with a phase 1a study in 48 healthy adults showing the drug was generally safe and well tolerated across all six planned dose cohorts.
The trial tested single doses given intravenously and subcutaneously: 0.1 mg/kg IV, 0.3 mg/kg IV, 100 mg SC, 1 mg/kg IV, 300 mg SC and 600 mg SC. Across those cohorts, treatment-emergent adverse events were mild or moderate and transient. The company said there were no deaths, no serious adverse events and no severe treatment-emergent adverse events at any dose. No clinically significant changes were seen in vital signs, laboratory tests or electrocardiograms. Anti-drug antibody results are still pending.
The pharmacokinetic readout showed target-mediated drug disposition at low concentrations, which Tectonic said confirmed TX2100’s high-affinity binding to the APJ receptor and clearance through that mechanism. The company said those data support once-weekly and every-other-week subcutaneous dosing in later studies.
Tectonic also said the dose range for upcoming studies was supported by two independent approaches: exposures tied to high receptor occupancy inferred from the phase 1a data and target exposure levels shown to drive activity in nonclinical HHT models. Both methods pointed to the same target exposure range.
On the regulatory side, the U.S. FDA granted TX2100 fast track designation for hereditary hemorrhagic telangiectasia and cleared Tectonic’s investigational new drug application for the planned U.S. phase 1b study. The company plans to start an open-label phase 1b trial in hematologic-support-dependent HHT patients by year-end 2026 and a placebo-controlled phase 2 trial in moderate-to-severe HHT in early 2027, with both studies running in parallel.
The phase 1b study is expected to look at changes in iron and red blood cell support and hematologic parameters. The phase 2 study is expected to measure epistaxis, hemoglobin, hematologic support and other HHT-related endpoints.
The phase 1a trial enrolled 48 volunteers, split evenly across six sequential cohorts of eight participants each, randomized 3:1 to TX2100 or placebo. Part b of the phase 1a study is already underway and has completed enrollment; it will dose six healthy volunteers with 600 mg SC on day 1, followed by 200 mg SC on days 8 and 15. Today the company's shares have moved -0.68% to a price of $23.51. For the full picture, make sure to review Tectonic Therapeutic's 8-K report.
