FDA Clears Pasithea's PAS-004 Trial for Neurofibromas

The agency has cleared an investigational new drug application for a placebo-controlled Phase 2 study of PAS-004 in NF1-associated cutaneous neurofibromas.

Updated on Nov. 3, 2026 in Cancer

Isometric editorial illustration of a single unlabeled amber glass vial beside plain white oral tablets on a pale slate surface, evoking an oral drug candidate. — The FDA cleared Pasithea Therapeutics' investigational new drug application for a placebo-controlled Phase 2 trial of oral MEK inhibitor PAS-004 in NF1-associated cutaneous neurofibromas. AI Illustration. Upload story photo >

The U.S. Food and Drug Administration cleared Pasithea Therapeutics Corp.'s Investigational New Drug application for a randomized, placebo-controlled Phase 2 trial of PAS-004 in NF1-associated cutaneous neurofibromas. The company may now proceed with Phase 2 clinical development of the oral MEK inhibitor in the United States.

Why it matters

There are currently no FDA-approved systemic therapies for NF1-associated cutaneous neurofibromas, which are benign skin tumors present in over 95% of people with NF1. Management today relies largely on surgical excision, electrodesiccation, or laser therapy.

The FDA clearance rests on nonclinical safety, clinical safety, tolerability and pharmacokinetic data, plus early treatment-response signals from an ongoing Phase 1/1b study in adults with NF1-associated plexiform neurofibromas. Whether PAS-004 shows efficacy in cutaneous neurofibromas has not yet been tested in the Phase 2 study.

The players

Pasithea Therapeutics Corp.

A clinical-stage biotechnology company listed on Nasdaq under the ticker KTTA that is developing PAS-004, a next-generation oral macrocyclic MEK inhibitor.

U.S. Food and Drug Administration

The federal agency that reviews and clears investigational drug applications and oversees drug approvals in the United States.

The details

Pasithea Therapeutics Corp., a clinical-stage biotechnology company listed on Nasdaq under KTTA, announced the clearance from Miami. The Phase 2 study will run under an active IND overseen by the FDA Division of Dermatology and Dentistry.

November 3, 2026: Pasithea announced FDA IND clearance for PAS-004 in cutaneous neurofibromas.

Big Picture

PAS-004 extends the MEK-inhibitor strategy already used for NF1-associated plexiform neurofibromas to the cutaneous form, which currently has no approved systemic therapy. If it succeeds, it would be the first such treatment for cNF.

For people with NF1, a successful systemic therapy could offer an alternative to surgery, electrodesiccation, or laser removal of skin tumors. Patients should note that PAS-004 remains investigational and is not yet available outside clinical trials.

The takeaway

Clearance to begin Phase 2 testing is an early step, not an approval. Readers with NF1 should watch for trial enrollment information and efficacy results before expecting a new treatment option.