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December 6, 2021
Company:

DyDo Group Holdings, Inc.

Representative:

Tomiya Takamatsu, President(Code 2590 on the First Section of the Tokyo Stock Exchange)

Inquiries:

Naokazu Hasegawa, Corporate Officerand General Manager of Corporate Communication Department

Notice of Phase 3 Clinical Trial Initiation in Japan by Consolidated Subsidiary

DyDo Pharma, Inc., a consolidated subsidiary of DyDo Group Holdings, Inc. (“Dydo Group”), has
initiated a Phase 3 clinical trial of amifampridine ("DYD-301") that is expected to be effective in treating thepatients with Lambert Eaton myasthenic syndrome (“LEMS”) in Japan.
DYD-301 is the therapeutic agent for LEMS that DyDo Pharma licensed from Catalyst Pharmaceuticals,Inc. (“Catalyst”) the joint exclusive development, & exclusive commercialization rights to amifampridine inJapan, and conducting clinical development in Japan.
Amifampridine has already been approved for use in the treatment of LEMS in Europe, the U.S. andCanada. Catalyst has already been marketing amifampridine tablets in the U.S. under the brand name ofFirdapse® since 2018.
Having identified the healthcare market, including the rapidly growing life science field, as its next growthdomain, the DyDo Group established DyDo Pharma in January, 2019 in an effort to focus on pharmaceuticals
for treating rare diseases (which are defined as the number of patients below 50,000 in Japan). Such diseases,
for which there are as yet no effective treatment options, have become a social issue. We, Dydo Pharma,
work to secure a promising products pipeline in an effort to develop pharmaceutical drugs for rare congenital
diseases and ultra rare diseases, which have even fewer patients, in order to address this issue.
As the effect of initiation of this clinical trial on consolidated financial performance during the fiscal year
ending January, 2022 has already been incorporated into the full year performance outlook that wasannounced on March 4, 2021, that outlook remains unchanged.

(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.

DYD-301 (amifampridine Tablets 10 mg)
DYD-301 is an oral, nonspecific, voltage-dependent, potassium (K+) channel blocker that causes
depolarization of the presynaptic membrane and slows or inhibits repolarization. This action results in theopening of slow voltage-dependent calcium (Ca2+) channels, allowing for a subsequent influx of Ca2+. In
turn, it induces the exocytosis of synaptic vesicles containing Acetylcholine (ACh) to release more ACh into
the synaptic cleft, enhancing neuromuscular transmission and providing for improved muscle function.
Amifampridine was granted orphan drug designation by the Ministry of Health, Labour and Welfare in Japanand has previously been approved for use in the United States, Europe, and Canada for the treatment of adults
with LEMS.

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 for Firdapse®
(amifampridine) 10 mg tablets for the treatment of adults with LEMS was approved in November, 2018 bythe U.S. Food & Drug Administration ("FDA"), and Firdapse® is commercially available in the United States
as a treatment for adults with LEMS. Further, Canada’s national healthcare regulatory agency, Health Canada,
recently approved the use of Firdapse® (amifampridine) for the treatment of patients in Canada with LEMS.

Licensing Agreement between Catalyst and DyDo Pharma
Please see the press release issued on June 28, 2021 for more information about the agreement.
Notice of a Consolidated Subsidiary’s Entry into a Licensing Agreement