Inhibikase Therapeutics Advances IKT-001 to Global Phase 3 Study for Pulmonary Arterial Hypertension
Key Insights
Inhibikase Therapeutics will advance IKT-001 (search), a novel prodrug of imatinib mesylate, directly to a global Phase 3 study for pulmonary arterial hypertension (search), skipping the planned Phase 2b trial.
The IMPROVE-PAH (search) study will use an adaptive two-part design with 140 patients in Part A and 346 patients in Part B, initiating in the first quarter of 2026 across approximately 180 global sites.
This single pivotal study approach accelerates the potential FDA approval timeline by approximately three years compared to the original development plan.
Inhibikase Therapeutics announced it will advance its lead candidate IKT-001 (search) directly to a global pivotal Phase 3 clinical study for pulmonary arterial hypertension (search) (PAH (search)), bypassing a planned Phase 2b trial and potentially accelerating FDA approval by approximately three years.
The clinical-stage pharmaceutical company received FDA feedback through a Type C meeting that supports transitioning immediately to the Phase 3 study, named IMPROVE-PAH (search) (IKT-001 (search) for Measuring Pulmonary Vascular Resistance and Outcome Variables in a Phase 3 Evaluation of PAH). The study is expected to initiate in the first quarter of 2026.
Novel Prodrug Design Addresses Previous Limitations
IKT-001 (search) is an investigational prodrug of imatinib mesylate, an anti-proliferative tyrosine kinase inhibitor. While imatinib demonstrated potential best-in-class improvements in pulmonary vascular resistance and 6-minute walk distance of 45 meters based on Phase 3 IMPRES and Phase 2 studies, high discontinuation rates impacted the results in previous trials.
"IKT-001 (search) is a prodrug of imatinib which is engineered to realize the potential of imatinib in PAH (search) and lower discontinuations in the forthcoming Phase 3 study," the company stated. The prodrug is designed with an expected improved gastrointestinal tolerability profile compared to imatinib.
Adaptive Phase 3 Study Design
The IMPROVE-PAH (search) study will employ a two-part adaptive design. Part A will be a double-blind, placebo-controlled study in 140 patients with a primary endpoint of pulmonary vascular resistance at Week 24. Part B will use an identical format but focus on 6-minute walk distance at Week 24 in 346 patients.
The adaptive design offers several advantages, including a 12-week dose-titration phase designed to help patients reach the highest tolerable dose of IKT-001 (search), uninterrupted enrollment between parts, and the ability to conduct sample size re-estimation for Part B based on Part A findings. The study will be conducted at approximately 180 sites worldwide.
Accelerated Development Timeline
Mark Iwicki, Chief Executive Officer of Inhibikase, emphasized the strategic advantage of the revised approach: "Our revised study plan for IKT-001 (search) in PAH (search) permits a single pivotal study format and thereby has the potential to advance our timeline to Phase 3 topline data readout and a potential NDA filing by approximately three years."
The company had originally planned to conduct a Phase 2b study in 150 subjects before advancing to Phase 3. The FDA's written responses now allow for the 12-week dose-titration phase, which the company believes will potentially allow patients to reach higher tolerable doses where imatinib has previously demonstrated the greatest benefit in exercise capacity and hemodynamics.
Addressing Unmet Medical Need
PAH (search) is a progressive, life-threatening disease characterized by pulmonary vascular remodeling and elevated pulmonary vascular resistance that affects approximately 50,000 Americans. The condition arises from aberrant signaling through the Abelson Tyrosine Kinase (search) and type III receptor tyrosine kinases, including platelet-derived growth factor receptors and c-KIT (search).
With over two decades of imatinib clinical experience and IKT-001 (search)'s expected improved tolerability profile, Inhibikase believes this supports a potentially higher probability of success for the upcoming Phase 3 study.