---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-226538"
form_type: "8-K"
ticker: "CPRX"
cik: "0001369568"
company_name: "CATALYST PHARMACEUTICALS, INC."
filed_at: "2024-09-26T23:59:59+00:00"
generated_at: "2026-05-31T01:29:41.421731+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Catalyst earns $2.1M milestone as Japan approves FIRDAPSE for LEMS

## Summary
- Japan's Ministry of Health approved DyDo's NDA for FIRDAPSE (amifampridine) 10 mg to treat Lambert-Eaton myasthenic syndrome (LEMS).
- Catalyst receives JPY 300 million (~$2.1M) milestone payment from sub-licensee DyDo upon approval.
- FIRDAPSE is the only FDA-approved LEMS treatment in the U.S.; approval expands access to Japan.
- Catalyst CEO says approval underscores commitment to expanding rare disease product portfolio beyond the U.S.

## SEC filing metadata
- accession: 0001193125-24-226538
- form_type: 8-K
- ticker: CPRX
- cik: 0001369568
- company_name: CATALYST PHARMACEUTICALS, INC.
- filed_at: 2024-09-26T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1369568/000119312524226538/0001193125-24-226538-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1369568/000119312524226538/d841208d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-226538
- JSON: https://secwatch.observer/filing/0001193125-24-226538.json
- Plain text: https://secwatch.observer/filing/0001193125-24-226538.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.