Pasithea Therapeutics Reports Positive Pharmacodynamic Results Demonstrating Robust Target Engagement from its Ongoing Phase 1 Clinical Trial of PAS-004

-- PAS-004 shows up to 91% inhibition of pERK, confirming substantial target engagement --

-- One patient in cohort 4A with stage 4 KRAS G12R mutated pancreatic cancer achieves over 5 months of stable disease with tumor volume reduction of -9.8% --

MIAMI, May 06, 2025 (GLOBE NEWSWIRE) -- Pasithea Therapeutics Corp. (NASDAQ: KTTA) (“Pasithea” or the “Company”), a clinical-stage biotechnology company developing PAS-004, a next-generation macrocyclic MEK inhibitor for the treatment of neurofibromatosis type 1 (NF1) and other MAPK pathway driven cancer indications, today announced positive interim pharmacodynamic (PD) data from its ongoing Phase 1 trial of PAS-004 in advanced cancer patients. The data includes results from cohorts 3 and 4A, evaluating 8mg and 15mg capsules, as well as cohort 4B evaluating 4mg tablets, and demonstrates strong target engagement consistent with PAS-004’s favorable pharmacological profile.

Inhibition of ERK phosphorylation (pERK) is widely recognized as a gold-standard PD biomarker for assessing MEK inhibitor activity. To evaluate target engagement, pERK levels were measured in peripheral blood mononuclear cells (PBMCs) collected from patients at baseline and steady-state at day 22.

Preliminary results demonstrate robust pERK inhibition, with reductions in pERK levels of up to 91% even at the 8mg dose level, in line with a previous developed PK/PD model, confirming substantial target engagement in patients receiving PAS-004.

Pharmacodynamic activity is supported by encouraging preliminary clinical observations, with several patients achieving stable disease and tumor shrinkage while on PAS-004 treament. Notably, one patient in cohort 4A (15mg capsule) with stage 4 KRAS G12R-mutated pancreatic cancer, having progressive disease while on three prior lines of therapy, achieved a tumor volume reduction of -9.8% over 5 months of PAS-004 treatment and currently remains on study.

“With today’s update, we are pleased that PAS-004 has demonstrated clinically meaningful reductions in pERK levels at dose levels that are both well-tolerated and safe, with no rash observed,” said Dr. Tiago Reis Marques, Chief Executive Officer of Pasithea. “We believe PAS-004’s profile offers the potential to finely modulate MAPK pathway activity, enabled by its previously reported long half-life and favorable pharmacokinetic (PK) profile with a Cmax/Cmin ratio below 2. We’re also encouraged by the emerging clinical signals we’re seeing across multiple cancer types and look forward to sharing further safety, PK and PD data in the coming months.”