PAS-004

June 30, 2026: Pasithea Therapeutics Corp. (NASDAQ: KTTA) reported updated interim safety, pharmacokinetic (PK), and clinical activity data (cutoff May 22, 2026) from its ongoing first-in-human Phase 1 dose-escalation trial of PAS-004, an oral macrocyclic MEK inhibitor, in patients with MAPK pathway–driven advanced solid tumors harboring RAS, NF1, or RAF mutations (NCT06299839), including patients previously treated with BRAF/MEK inhibitors.

Across 34 enrolled/dosed, heavily pretreated patients (median 3 prior lines), PAS-004 was described as well tolerated with once-daily dosing: no dose-limiting toxicities and no discontinuations due to treatment-related AEs; all TRAEs were Grade 1–2. Reported cumulative rash was 12% and diarrhea 6%, with no rash/diarrhea among patients treated >300 days; no retinal or cardiac toxicity events were observed. In a refractory subgroup (N=12), the company reported disease stabilization and durable benefit, including some prior MEK/BRAF-treated patients with stable disease >6 months and two >1 year.

PK findings included ~60-hour half-life, linear dose-proportional exposure, Cmax/Cmin ratio <2, and concentrations above cellular IC50 at all cohorts. The protocol was amended to continue dose escalation (tablet formulation) to 18–52 mg and to initiate an optional pilot food-effect study (fed vs. fasted). The company plans to submit/present a larger dataset at a future scientific conference and noted an ongoing Phase 1/1b study in adult NF1-associated plexiform neurofibromas (NCT06961565).