Pasithea Therapeutics Activates South Korean Clinical Trial Sites for PAS-004 Study

Pasithea Therapeutics Corp. has activated two South Korean clinical trial sites to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of PAS-004, a next-generation macrocyclic MEK inhibitor, in adult participants with neurofibromatosis type 1 (NF1) and symptomatic plexiform neurofibromas. The trial sites, ASAN Medical Centre and Severance Hospital Yonsei University Health System, are actively recruiting participants.

Pasithea Therapeutics Corp. has reported positive safety results from the initial phase of its Phase 1/1b clinical trial of PAS-004, a next-generation macrocyclic MEK inhibitor, in adult participants with neurofibromatosis type 1 (NF1) and symptomatic plexiform neurofibromas. The external safety committee cleared the escalation to the 8 mg tablet dose, prompting the enrollment of the first three patients in Cohort 2. The study is being conducted at two South Korean clinical trial sites: ASAN Medical Centre and Severance Hospital Yonsei University Health System, which are actively recruiting participants Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].

The trial, identified as NCT06961565, is divided into two parts. Part A will enroll up to 24 participants across four dose levels (4, 8, 12, 18 mg) to establish a recommended Part B dose. Part B will then randomize approximately 24 participants to the selected dose and a lower dose for up to six 28-day cycles to define the recommended phase 2 dose (RP2D). The study aims to characterize pharmacokinetics/pharmacodynamics (PK/PD) and generate early signals on neurofibroma volume, cutaneous neurofibroma burden, pain, function, and quality of life, with exploratory tissue and molecular analyses in cutaneous neurofibromas (CNs) Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].

Pasithea Therapeutics is strategically positioning itself in the MEK inhibitor landscape by targeting adult NF1, a population with fewer labeled options than pediatrics and a need for chronic, tolerable regimens. The company is also aiming for a broader clinical value proposition by including cutaneous endpoints and symptom measures. The initial interim data from the first two cohorts is targeted for Q1 2026, signaling a measured escalation pace and the need for sufficient exposure and imaging timepoints before calling a signal Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].

The study's operational complexity includes volumetric MRI, dermatologic assessments, and layered patient-reported outcomes (PROs). This complexity may pressure smaller centers unless the sponsor and CRO provide strong enablement. Cross-border site distribution may help recruitment in a dispersed adult NF1 population but also raises harmonization needs for imaging and symptom scales across regions. Vendors focused on central imaging, digital symptom capture, and remote safety surveillance stand to benefit if the study scales on schedule Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].

Sponsors and regulators will be watching whether PAS-004 can maintain a clean safety profile as doses escalate to 12 mg and 18 mg and whether PD readouts tie to early volumetric changes. With pediatric NF1 already established as a MEK-sensitive setting and multiple adult programs moving in parallel, differentiation will likely hinge on chronic tolerability and consistency of symptom relief rather than headline response rates alone. Alignment on adult endpoints—particularly the weight regulators’ place on volumetric reduction versus pain and function—remains a live question that could shape Part B refinement and any subsequent pivotal strategy Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].

Near term, the key catalysts are the absence of dose-limiting toxicities (DLTs) at higher doses, selection of the Part B dose, and the character of the first PN and CN signals in early 2026. Any signal that sustained dosing is feasible with manageable class-associated toxicities would justify the adult NF1 bet and inform the design of a registrational path. Conversely, tolerability setbacks or inconclusive PD-efficacy linkage would push PAS-004 back into a crowded MEK field competing largely on class sameness rather than differentiation Pasithea NF1 Trial Advances to Cohort 2 on Positive Safety^[1].