-- Prolonged Stable Disease: PAS-004 achieved prolonged stable disease in a heavily pre-treated population, with four patients on PAS-004 for more than 300 days, including two who continue on once daily PAS-004 for over 500 days despite recurrent, metastatic melanoma carrying the BRAF V600E mutation and prior progression on targeted combination therapy with dabrafenib and trametinib. -- Long-Term Tolerability: Overall, the safety profile of PAS-004 in the heavily pre-treated advanced cancer population appears favorable. No Grade 3 treatment-related adverse events (“AEs”), no discontinuations due to treatment-related AEs, and no related serious AEs have been reported. Treatment-related AEs remain low-grade and manageable, with low rates of vomiting, nausea, diarrhea, and rash, including none reported by the four patients on-study for >300 days. None of the MEKi class effects on the heart or the retina have been reported. To date, there have been no dose-limiting toxicities, and the maximum tolerated dose has not been reached. -- Favorable Pharmacokinetic Profile: PAS-004 demonstrated a long half-life, approximately 58 hours on average, with a low Cmax/Cmin ratio of less than 1.5. AUC increased proportionally in this dose escalation study. The flat pharmacokinetic curve with a long half-life supports long-term, chronic dosing. MIAMI , Oct. 23, 2026 (GLOBE NEWSWIRE) -- Pasithea Therapeutics Corp. (Nasdaq: KTTA) (“Pasithea” or the “Company”), a clinical-stage biotechnology company developing PAS-004, a next-generation macrocyclic oral MEK inhibitor, today announced updated safety, tolerability, and preliminary efficacy data from its ongoing Phase 1 dose-escalation study of PAS-004 monotherapy in a heavily pre-treated population of patients with MAPK pathway-driven advanced solid tumors harboring RAS, NF1 or RAF mutations, including patients who have failed prior BRAF/MEK inhibitor treatment (NCT06299839). The data, reflecting durable clinical benefit, including prolonged stable disease in four patients, as well as long-term tolerability and flat pharmacokinetics, are being presented today at the ESMO Congress 2026, taking place October 23-27, 2026 , in Madrid, Spain . “The prolonged stable disease that we’re seeing in some patients across this heavily pre-treated population is highly encouraging, particularly in patients with BRAF V600E-mutant tumors who previously progressed on BRAFi monotherapy and/or BRAFi/MEKi combination therapy. The literature reports a median progression-free survival of approximately five months for combination BRAFi/MEKi rechallenge in this setting, and some patients in the BRAF-mutant subgroup are exceeding that benchmark with our MEKi monotherapy,” said Dr. Kartik Krishnan , Chief Medical Officer of Pasithea. “What makes this data especially encouraging is that we’re seeing these signals of durable clinical benefit alongside a long-term tolerability profile that continues to hold up. No patient has discontinued treatment at any dose level due to treatment-related adverse events, and we continue to observe low rates of vomiting and other GI toxicity, low rates of rash, even in patients taking PAS-004 continuously for long periods of time. A tolerability profile like this is exactly what you want to see for the long-term treatment of chronic diseases including neurofibromatosis type 1 (NF1).” Details of the Presentation: Title: Phase I Dose-Escalation Study of the Safety and Pharmacokinetics of PAS-004, a Macrocyclic MEK Inhibitor, for the Treatment of Patients with MAPK Pathway Driven Advanced Solid Tumors Abstract/Poster Number: 1050P Session: Developmental Therapeutics Date/Time: Friday, October 23, 2026 , 15:15–16:00 CEST Key Findings (Data as of 15 September 2026): Enrollment: 37 patients enrolled in dose escalation across 10 dose cohorts (2mg, 4mg, 8mg, 15mg, 22mg, 30mg, 37mg and 45mg capsule formulations, and 4mg and 18mg tablet formulations). Patient Population: Heavily pre-treated population with a median of 3 prior lines of therapy (range 1–8); median age 57 years; 54.1% (n=20) female; most common tumor types were colorectal (38%, n=14), melanoma (30%, n=11) and pancreatic (16%, n=6). BRAF-Mutant Patients: 12 patients enrolled with BRAF V600E mutations, 10 of whom previously progressed on BRAF and/or BRAF/MEK combination therapy. Prolonged Stable Disease: Four patients have been on PAS-004 for greater than 300 days; two patients remain on treatment for more than 500 days with prolonged stable disease. Safety: No dose limiting toxicities were observed. No patient has discontinued PAS-004 due to treatment-related adverse events (TRAEs). No grade ≥3 were observed. TRAEs reported in 45.9% (17 of 37) of patients; all Grade 1 or 2. Most common TRAEs: nausea (14%), vomiting (11%), rash (11%), blood creatine phosphokinase increased (11%) and diarrhea (5%). Cumulative rates of rash and gastrointestinal toxicities have remained low across all patients at all doses, with no MEKi-associa