June 28, 2021
DyDo Pharma, Inc.

Notice of a Licensing Agreement for a Pharmaceutical for Treating Lambert-Eaton
Myasthenic Syndrome
DyDo Pharma, Inc., (Head Office: Kita-ku, Osaka; president and representative director: Yasunori Inaoka)
has entered, effective today, into a licensing and supply agreement covering Japanese market with Catalyst
Pharmaceuticals, Inc., for the development and commercialization of amifampridine that is expected to prove
to be effective in treating Lambert-Eaton myasthenic syndrome (“LEMS”).
Amifampridine has already been approved for use in the treatment of LEMS in Europe, the U.S. andCanada. Catalyst, which markets and sells amifampridine tablets in the U.S. under the Firdapse® brand name.
With this agreement, DyDo Pharma acquires from Catalyst joint exclusive development and selling rights
as well as exclusive commercialization rights to amifampridine in Japan where DyDo Pharma will develop
and commercialize the product.
“DyDo Pharma’s experienced team and commitment to rare diseases makes the company an attractive
strategic development and distribution partner for Catalyst and for our amifampridine product Firdapse® forthe treatment of LEMS,” said Patrick J. McEnany, Chairman and CEO of Catalyst. “Given the limited
availability of treatment options for LEMS in Japan, we look forward to working with DyDo Pharma toaddress this unmet medical need by hopefully providing a new treatment option for patients and their families.”“We are very pleased to have acquired a license for the Japanese rights for Firdapse®, which Catalyst
sells in the U.S.,” said Yasunori Inaoka, president and representative director of DyDo Pharma. “Goingforward, we will pursue development with the goal of obtaining marketing authorization approval forFirdapse® as a treatment for LEMS in Japan so that we can offer a new therapeutic option to Japanese
LEMS patients, who with their families are currently suffering in the absence of an approved treatment.”(Reference)
Lambert-Eaton myasthenic syndrome
Lambert-Eaton myasthenic syndrome is an autoimmune neuromuscular disorder in which a reduction inacetylcholine release from nerve terminals results in proximal muscle weakness, autonomic nervous
symptoms, and other symptoms. It is one of a number of paraneoplastic neurological syndromes thataccompany malignant tumors or precede tumors.
Catalyst pharmaceuticals
Catalyst Pharmaceuticals is a commercial-stage, patient-centric biopharmaceutical company focused onin-licensing, developing and commercializing novel high-quality medicines for patients living with rarediseases. With exceptional patient focus, Catalyst is committed to developing a robust pipeline of cuttingedge, first- or best-in-class medicines for other rare diseases. Catalyst's New Drug Application forFirdapse® (amifampridine) 10 mg tablets for the treatment of adults with LEMS was approved in 2018 bythe U.S. Food & Drug Administration ("FDA"), and Firdapse® is commercially available in the UnitedStates as a treatment for adults with LEMS. Further, Canada’s national healthcare regulatory agency, HealthCanada, recently approved the use of Firdapse® (amifampridine) for the treatment of patients in Canadawith LEMS.