Pasithea Therapeutics Announces Positive Interim Phase 1 Advanced Cancer Study Data Demonstrating Long-Term Safety and Tolerability, and Durable Clinical Activity in MEK/BRAF-Pretreated Patients, plus Protocol Expansion
Rhea-AI Summary
Pasithea Therapeutics (Nasdaq: KTTA) reported positive interim Phase 1 data for PAS-004, an oral MEK inhibitor in advanced MAPK pathway-driven solid tumors, including MEK/BRAF-pretreated patients.
Among 34 heavily pretreated patients, PAS-004 showed a favorable safety profile, durable disease stabilization beyond six months in several cases, and pharmacokinetics supporting once-daily chronic dosing. A protocol amendment extends dose escalation with a tablet formulation up to 52mg and adds a pilot food-effect study.
AI-generated analysis. How Rhea-AI works. Not financial advice.
Positive
- All treatment-related adverse events were Grade 1–2 with no dose-limiting toxicities
- No retinal or cardiac toxicity and low rash (12%) and diarrhea (6%) rates reported
- No discontinuations due to treatment-related adverse events, with 2 patients on therapy >365 days
- Evidence of disease stabilization and tumor shrinkage in refractory, MEK/BRAF-pretreated patients
- Pharmacokinetics show ~60-hour half-life and Cmax/Cmin <2, supporting once-daily dosing
- Protocol expansion to explore higher tablet doses up to 52mg and optimize dosing via food-effect study
Negative
- Data are interim Phase 1 results; final progression-free survival will be known only at trial completion
News Market Reaction – KTTA
On the day this news was published, KTTA declined 2.03%, reflecting a moderate negative market reaction. Argus tracked a peak move of +15.6% during that session. Argus tracked a trough of -18.5% from its starting point during tracking. Our momentum scanner triggered 20 alerts that day, indicating elevated trading interest and price volatility. This price movement removed approximately $422K from the company's valuation, bringing the market cap to $20.38M at that time. Trading volume was exceptionally heavy at 54.0x the daily average, suggesting significant selling pressure.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Previous Clinical trial Reports
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Jun 16 | Protocol amendment | Positive | -8.9% | Expanded PAS-004 NF1 trial protocol with higher doses and longer treatment. |
| Jun 02 | Orphan designation ALS | Positive | -9.8% | FDA granted Orphan Drug Designation to PAS-004 for ALS treatment. |
| Apr 01 | Fast Track NF1 | Positive | +0.3% | FDA Fast Track designation for PAS-004 in NF1 plexiform neurofibromas. |
| Nov 24 | Cohort 7 completion | Positive | +45.3% | Completed PAS-004 Cohort 7 in cancer trial with positive safety and PK/PD data. |
| Nov 21 | Tablet PK data | Positive | -29.6% | Reported favorable tablet PK profile for PAS-004 in NF1 Phase 1/1b trial. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
KTTA has often traded weakly on positive clinical updates, with more declines than gains after such news.
Key Terms
pharmacokinetics medical
maximum tolerated dose medical
ic50 medical
cmax medical
cmin medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
-- Favorable Safety Profile Supports Long-Term Chronic Dosing: PAS-004 has been well-tolerated, with all treatment-related adverse events (TRAEs) being Grade 1 or 2, no observed cardiac or retinal treatment-related events, and low rates of rash and gastrointestinal toxicities
-- Protocol Amendment Extends Dose Escalation to Higher Levels: Continued dose escalation using tablet formulation to explore 18mg, 24mg, 30mg, 40mg, and up to 52mg dose levels to further characterize safety, pharmacokinetics (PK), and early efficacy signals at higher doses
-- Potential Best-in-Class MEK Inhibitor Profile Emerging: Interim PK and safety data at pharmacologically active doses support PAS-004 as a differentiated candidate with potential for long-term chronic dosing with favorable tolerability
-- Pilot Food Effect Study Initiated: An optional pilot food effect assessment has been introduced to evaluate the impact of fed vs. fasted administration on PAS-004 pharmacokinetics, to optimize long-term dosing strategy
MIAMI, June 30, 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, for the long-term treatment of chronic diseases including the neurocutaneous manifestations of neurofibromatosis type 1 (NF1), today announced updated interim safety and clinical activity data from its ongoing first-in-human trial evaluating PAS-004 in patients with MAPK pathway-driven advanced solid tumors with a documented RAS, NF1 or RAF mutation, including patients who have failed prior BRAF/MEK inhibitor treatment (NCT06299839). The Company also announced details of its protocol amendment to extend dose escalation and initiate a pilot food effect assessment.
Dr. Kartik Krishnan, Chief Medical Officer of Pasithea, said, “The literature reports that patients with BRAF mutated cancer who progress on BRAF/MEK combination therapy have a median progression-free survival of approximately 5 months with rechallenge with BRAF/MEK combination therapy. We have observed that a number of these patients who previously progressed on prior BRAF/MEK inhibitor treatment have demonstrated stable disease on PAS-004 for greater than six months, including two patients for over one year. We believe that this demonstrates that PAS-004 is an active agent. Importantly, we continue to be encouraged by the observed adverse event (AE) profile and the ability to maintain dosing in patients over a long period of time without discontinuations. Given that we have not reached the maximum tolerated dose (MTD) and the tolerability of the doses we have evaluated to date, we have decided to continue dose escalation in the study with the introduction of our tablet formulation, while also exploring the effect of food on the PK of PAS-004 to enhance our understanding about how best to maximize the benefit of PAS-004 in long-term chronic dosing.”
Interim Phase 1 Results for PAS-004 through May 22, 2026:
- 34 patients have been enrolled and dosed
- Heavily pre-treated population with a median of 3 prior lines of therapy (range 1 – 8)
- Difficult to treat diagnoses (e.g., refractory pancreatic cancer and ovarian cancer), including 12 patients with BRAF V600E mutations, 10 of whom previously progressed on BRAFi and/or BRAFi/MEKi combinations
- Well-tolerated safety profile with long-term, once daily dosing
- No dose-limiting toxicities (DLTs), and no discontinuations due to TRAEs with 10 patients on study for >90 days, of which 6 patients >150 days, 4 patients >300 days, and 2 patients >365 days
- All TRAEs were Grade 1 or Grade 2; Low cumulative rates of rash (
12% ) and diarrhea (6% ) across all patients at all doses throughout the study, including no (0% ) rash or diarrhea in the 4 patients on study >300 days and 2 patients >365 days - No events of retinal or cardiac toxicity
- Disease stabilization in the refractory population (N=12)
- Multiple patients demonstrating durable clinical benefit and tumor shrinkage, including several MEK/BRAF-pretreated patients who have remained on study for greater than six months and two patients on study for over one year – exceeding the approximately 5-month median PFS reported in the literature for BRAF/MEK rechallenge in this setting. The final PFS data will not be known until the end of the trial.
- Pharmacokinetics support daily dosing and exploration of higher dose levels
- Long half-life (approximately 60 hours)
- Linear, dose proportional PK
- Cmax/Cmin ratio <2, with both Cmax and Cmin above the IC50 (half-maximal inhibitory concentration) from our cellular assay at all dose cohorts
The Company plans to submit and present a more robust data set at a future scientific conference.
About Pasithea Therapeutics Corp.
Pasithea is a clinical-stage biotechnology company primarily focused on the research and development of its lead drug candidate, PAS-004, a next-generation macrocyclic MEK inhibitor intended for the treatment of RASopathies, MAPK pathway-driven tumors, and other diseases. The Company is currently testing PAS-004 in a Phase 1 clinical trial in advanced cancer patients (NCT06299839), and a Phase 1/1b clinical trial in adult patients with neurofibromatosis type 1 (NF1)-associated plexiform neurofibromas (NCT06961565).
Forward Looking Statements
This press release contains statements that constitute “forward-looking statements” made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include statements regarding the Company’s ongoing Phase 1 clinical trial of PAS-004 in advanced cancer patients, the Company’s Phase 1/1b clinical trial of PAS-004 in adult NF1 patients, and the safety, tolerability, pharmacokinetic (PK), pharmacodynamics (PD) and preliminary efficacy of PAS-004, as well as all other statements, other than statements of historical fact, regarding the Company’s current views and assumptions with respect to future events regarding its business, as well as other statements with respect to the Company’s plans, assumptions, expectations, beliefs and objectives, the success of the Company’s current and future business strategies, product development, pre-clinical studies, clinical studies, clinical and regulatory timelines, market opportunity, competitive position, business strategies, potential growth and financing opportunities and other statements that are predictive in nature. Forward-looking statements are subject to numerous conditions, many of which are beyond the control of the Company. While the Company believes these forward-looking statements are reasonable, undue reliance should not be placed on any such forward-looking statements, which are based on information available to the Company on the date of this release. These forward-looking statements are based upon current estimates and assumptions and are subject to various risks and uncertainties, including risks that future clinical trial results may not match results observed to date, may be negative or ambiguous, or may not reach the level of statistical significance required for regulatory approval, as well as other factors set forth in the Company’s most recent Annual Report on Form 10-K, Quarterly Report on Form 10-Q and other filings made with the U.S. Securities and Exchange Commission (SEC). Thus, actual results could be materially different. The Company undertakes no obligation to update these statements whether as a result of new information, future events or otherwise, after the date of this release, except as required by law.
Contact
Patrick Gaynes
Corporate Communications
pgaynes@pasithea.com
