8-K: Pasithea's PAS-004 Shows Positive Trial Data, Secures ALS Grant

Pasithea Therapeutics announced positive Phase 1 clinical trial data for its drug candidate PAS-004 across advanced cancer and NF1, alongside a $1 million grant from the ALS Association to study PAS-004 for ALS treatment.

Summary

• PAS-004 demonstrated positive interim Phase 1 data in advanced cancer patients, including a partial response in a BRAF V600E melanoma patient (31.9% tumor reduction) who remains on trial for over 11 months.
• The overall Disease Control Rate (DCR) was 42.8% (9 of 21 efficacy evaluable patients) and 71.4% (5 of 7) for BRAF-mutated tumors.
• PAS-004 was well-tolerated across all dose levels (up to 37mg capsule), with no dose-limiting toxicities (DLTs) or discontinuations reported among 27 dosed patients through the cutoff date of November 10, 2025.
• All treatment-related adverse events (TRAEs) were Grade 1 or 2, with limited rash (7.4%), nausea (18.5%), vomiting (14.8%), and diarrhea (7.4%), and no ocular or cardiovascular toxicities.
• Pharmacokinetic (PK) data showed linear PK, dose-proportionality, a Cmax/Cmin ratio <2, and a long half-life (~60 hours for capsule, ~57 hours for tablet).
• Cohort 6 (30mg capsule) showed AUC of ~5,480 ng*h/mL, Cmax of 249 ng/mL, and Cmin of 215 ng/mL.
• Cohort 7 (37mg capsule) showed AUC of 6,690 ng*h/mL, Cmax of 313 ng/mL, and Cmin of 260 ng/mL, with zero treatment-related adverse events observed during the DLT period.
• Pharmacodynamic (PD) data from Cohort 7 showed PAS-004 inhibiting phosphorylated extracellular signal-regulated kinase (pERK) at 80% near Cmax and above 60% at Cmin (24-hour predose), supporting continuous MAPK pathway suppression.
• The Safety Review Committee recommended escalating to Cohort 8 (45mg capsule) without modification.
• A new tablet formulation of PAS-004 showed approximately 3-fold higher dose-normalized exposures compared to the capsule formulation, with less patient variability and similar Tmax.
• The 8mg tablet achieved AUC of 2,290 ng*h/mL, Cmax of 118 ng/mL, and Cmin of 75.4 ng/mL, which is slightly greater than the 22mg capsule.
• The ALS Association awarded a Hoffman ALS Clinical Trial Award grant worth ~$1 million to study PAS-004 in ALS patients, funding a Phase 1 study in twelve ALS patients across three dose cohorts for approximately 28 weeks.

Sentiment

Score: 8

Explanation: The filing presents overwhelmingly positive clinical trial data across multiple indications, highlighting strong safety, favorable PK/PD, and initial efficacy signals. The significant grant award from the ALS Association further validates the drug's potential and expands its development pipeline, indicating strong positive momentum for the company.

Positives

• Demonstrated monotherapy clinical activity with an unconfirmed partial response (31.9% tumor reduction) in a MEK-rechallenge 3rd-line melanoma patient with BRAF V600E mutation who remains on trial for over 11 months.
• High Disease Control Rate (DCR) of 71.4% in BRAF-mutated tumors and 42.8% overall in efficacy evaluable patients.
• Excellent safety and tolerability profile with no dose-limiting toxicities (DLTs) or discontinuations, and all treatment-related adverse events (TRAEs) being Grade 1 or 2.
• Zero treatment-related adverse events observed during the DLT period for Cohort 7 (37mg capsule).
• Absence of ocular retinal abnormalities or cardiovascular toxicities, which are common with other MEK inhibitors.
• Favorable pharmacokinetic (PK) profile with linear PK, dose-proportionality, a Cmax/Cmin ratio <2, and a long half-life, suggesting sustained pathway inhibition.
• Pharmacodynamic (PD) data supports continuous suppression of the MAPK pathway throughout the once-daily 24-hour cycle, avoiding excessive suppression or insufficient target engagement.
• Safety Review Committee recommended dose escalation to Cohort 8 (45mg capsule) without modification, indicating continued confidence in safety.
• Tablet formulation offers improved PK properties, including approximately 3-fold higher dose-normalized exposures, less patient variability, and similar Tmax compared to the capsule.
• Secured a ~$1 million grant from the ALS Association to initiate a Phase 1 clinical trial for PAS-004 in ALS patients, expanding the drug's potential indications.
• PAS-004 has shown promising results in the ALS gold standard SOD mouse model.

Negatives

• The partial response observed in advanced cancer patients is currently unconfirmed.
• The efficacy data is still preliminary from a Phase 1 dose-escalation trial, primarily focused on safety and PK/PD, and involves a limited number of patients.
• The Disease Control Rate (DCR) includes stable disease, which, while positive, does not represent tumor shrinkage.

Risks

• 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.
• The success of 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 are subject to numerous conditions beyond the company's control.
• Actual results could be materially different from forward-looking statements.

Future Outlook

Pasithea Therapeutics anticipates PAS-004's balanced pharmacological profile will be critical for achieving clinical efficacy while minimizing adverse events, particularly for chronic dosing in MAPK pathway-driven diseases like NF1-PN. The company believes PAS-004 has the potential to be a best-in-class MEK inhibitor and is expanding its clinical evaluation into ALS patients, aiming to provide proof-of-concept for multiple indications.

Management Comments

• "We are highly encouraged by the initial safety data generated in Cohort 7 (37mg capsule), where zero treatment-related adverse events have been observed during the DLT period." Dr. Tiago Reis Marques, Chief Executive Officer.
• "PD data demonstrates the pharmacological profile we believe is necessary to achieve consistent pathway inhibition over a once daily 24-hour dosing period, while avoiding both periods of excessive suppression and periods of insufficient target engagement." Dr. Tiago Reis Marques, Chief Executive Officer.
• "We believe this balanced profile will be critical for achieving clinical efficacy while minimizing the most commonly observed adverse events associated with MEK inhibitors." Dr. Tiago Reis Marques, Chief Executive Officer.
• "We believe PAS-004 is particularly well suited for the treatment of diseases involving the MAPK pathway that require chronic dosing over long periods of time, where sustained long-term pathway suppression at safe and well-tolerated doses is required." Dr. Tiago Reis Marques, Chief Executive Officer.
• "Today’s updated interim results from our advanced cancer trial demonstrate the safety, PK and anti-tumor activity of PAS-004, and support its potential to be a best-in-class MEK inhibitor for the treatment of NF1-PN." Dr. Tiago Reis Marques, Chief Executive Officer.
• "Achieving a monotherapy partial response in an advanced cancer patient who had previously received a MEK + BRAF inhibitor combination therapy, and whose prior best response had been stable disease, is very promising." Dr. Tiago Reis Marques, Chief Executive Officer.
• "At our highest reported cohort (30mg capsule), we are seeing significant drug exposures (Area Under the Curve (AUC) greater than 5,400 ngh/mL), with a relatively flat PK curve, suggesting sustained pathway inhibition. We believe this profile is well aligned with what is needed to drive meaningful clinical responses in NF1-PN patients." Dr. Tiago Reis Marques, Chief Executive Officer.
• "I find it very encouraging that even when used as a monotherapy in advanced recurrent cancer patients, PAS-004 has demonstrated early signals of efficacy, but more importantly exhibited such a favorable safety profile that no dose interruptions or modifications were required." Dr. Rebecca Brown, Director of the Neurofibromatosis (NF) and Schwannomatosis (SWN) Program at University of Alabama Birmingham (UAB) and Scientific Advisory Board member of Pasithea.
• "Maintaining NF1-PN patients on treatment for extended periods of time is paramount to achieving maximum tumor control. I believe that PAS-004’s early efficacy signals combined with the low rate of adverse side effects may translate into better tolerability and longer time-on-treatment for plexiform neurofibromas associated with NF1, compared with current FDA-approved therapies discontinuation rates estimated as high as 40-50% before year two." Dr. Rebecca Brown.
• "We are honored that the ALS Association recognizes the promise of PAS-004. Its support enables the initiation of the first clinical trial of PAS-004 in individuals living with ALS, which is a significant milestone for Pasithea as we look to provide proof-of-concept that PAS-004 may be the best-in-class MEK inhibitor for the treatment of many indications." Dr. Lawrence Steinman, Chairman of Pasithea.
• "I am delighted to continue working on the development of potentially effective treatments for ALS. PAS-004 targets a critical molecule in the pathophysiology of motor neuron disease and has delivered significant and promising results in the ALS gold standard SOD mouse model." Dr. Lawrence Steinman, Chairman of Pasithea.
• "Inflammation and the aggregation of a protein called TDP-43 are well-recognized contributors to the development and progression of ALS. Two enzymes, mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (MEK), have been shown to play a role in TDP-43related neurodegeneration and neuroinflammation, suggesting they represent promising therapeutic targets." Dr. Tiago Reis Marques, Chief Executive Officer.

Industry Context

The biotechnology industry is highly competitive, particularly in oncology and rare diseases. MEK inhibitors are a class of drugs used in cancer treatment, but often come with significant side effects leading to high discontinuation rates. PAS-004's emerging profile, characterized by a favorable safety profile, sustained pathway inhibition, and potential for chronic dosing, positions it as a potentially differentiated candidate. The expansion into ALS, a disease with high unmet need and limited treatment options, further diversifies its potential market and addresses a critical area of neurological research, supported by a prestigious grant from the ALS Association.

Comparison to Industry Standards

• PAS-004's favorable safety profile, with all treatment-related adverse events (TRAEs) being Grade 1 or 2 and no ocular or cardiovascular toxicities, compares favorably to current FDA-approved MEK inhibitors which often have higher rates of severe adverse events and specific toxicities.
• The low rate of adverse side effects and no dose interruptions or modifications for PAS-004 suggest better tolerability and potentially longer time-on-treatment for NF1-PN patients compared to current FDA-approved therapies, which have estimated discontinuation rates as high as 40-50% before year two.
• Achieving a monotherapy partial response in a MEK-rechallenge 3rd-line melanoma patient, whose prior best response to a MEK + BRAF combination therapy was stable disease, indicates a potentially superior or differentiated efficacy profile for PAS-004 in this challenging patient population.
• The sustained pathway inhibition (pERK inhibition above 60% at Cmin) and Cmax/Cmin ratio <2 suggest a more balanced and consistent target engagement compared to some MEK inhibitors that may have more pronounced peak-trough fluctuations, potentially leading to better efficacy and tolerability.
• The 3-fold higher dose-normalized exposures and reduced patient variability with the tablet formulation compared to the capsule formulation represent an improvement in drug delivery and predictability, which is a significant advantage in clinical practice.

Stakeholder Impact

• Shareholders: Positive impact due to promising clinical trial results, expansion into new indications (ALS), and external funding, potentially increasing company valuation and future revenue streams.
• Patients (Advanced Cancer, NF1, ALS): Potential for a new, well-tolerated, and effective treatment option for severe diseases with high unmet medical needs.
• Employees: Positive impact from successful drug development and expanded research initiatives, potentially leading to job security and growth opportunities.
• Regulatory Authorities: Continued positive data could streamline future regulatory approvals.
• ALS Association: Successful trial results would validate their grant investment and contribute to their mission of finding treatments for ALS.

Next Steps

• Escalate the Phase 1 trial in advanced cancer patients to Cohort 8 (45mg capsule).
• Continue the ongoing Phase 1 clinical trial of PAS-004 in advanced cancer patients (NCT06299839).
• Continue the ongoing Phase 1/1b clinical trial of PAS-004 in adult NF1 patients (NCT06961565).
• Initiate a Phase 1 clinical trial to study PAS-004 in twelve ALS patients across three sequential dose cohorts, with follow-up for approximately 28 weeks.
• Measure changes in ALS Functional Rating Scale-Revised (ALSFRS-R) scores and neurofilament light chain (NfL) levels in the ALS study to explore potential early signals of clinical activity.

Key Dates

Recommendation

The comprehensive positive data across multiple clinical trials for PAS-004, including a partial response in a challenging cancer patient population, an excellent safety profile, and favorable pharmacokinetic/pharmacodynamic characteristics, significantly de-risks the drug candidate. The successful development of a superior tablet formulation and the substantial grant from the ALS Association to expand into a new, high-need indication (ALS) further enhance the company's pipeline and market potential. These factors collectively suggest a strong positive outlook for the company's future growth and valuation, warranting a 'strong buy' recommendation for a seasoned investor.

Keywords

PAS-004, MEK inhibitor, advanced cancer, neurofibromatosis type 1, NF1-PN, ALS, clinical trial, Phase 1, pharmacokinetics, pharmacodynamics, safety, tolerability, MAPK pathway, biotechnology, oncology, neurology, rare disease, drug development