PeptiDream 与 MSD 合作项目达成开发里程碑，触发未披露里程碑付款

News Release

October 7, 2026

PeptiDream Inc.
https://www.peptidream.com/en/
(TSE Prime Market: 4587)

PeptiDream Announces Achievement of Development Milestone
in Collaboration with MSD

A candidate being developed under a collaboration and license agreement
with MSD has advanced triggering an undisclosed milestone payment to
Peptidream.
The advancement highlights the continued progress of the companies’
development efforts.

KAWASAKI, JAPAN – October 7, 2026 - PeptiDream Inc. ("PeptiDream"), a public
biopharmaceutical company based in Kawasaki, Japan, focused on the discovery and
development of peptide-based therapeutics, today announced that it has achieved a
development milestone for a peptide cytotoxic conjugate (PCC) program under its ongoing
collaboration with MSD (tradename of Merck & Co., Inc., Rahway, NJ, USA).

This advancement highlights the broad applicability of PeptiDream’s proprietary Peptide
Discovery Platform System (PDPS®) in the growing field of PCCs. Under the agreement,
PeptiDream provides peptide candidates identified and optimized utilizing its PDPS®
technology for use against targets of interest selected by MSD. MSD has exclusive rights to
the peptide candidates and is responsible for all development aspects of any PCC products
arising from the collaboration.

“We are extremely pleased to have achieved this important milestone in our collaboration with
MSD,” said Patrick C. Reid, Ph.D., Representative Director, CEO of PeptiDream. “This
important achievement highlights the strength and versatility of our PDPS® platform and
underscores the potential of this emerging therapeutic modality. We look forward to continuing
to work closely with MSD to advance this program.”

The advancement of this program triggered an undisclosed milestone payment from MSD to
PeptiDream.
This achievement has been factored into our consolidated financial forecasts for the fiscal year
ending December 31, 2026, which was announced on February 16, 2026, and there are no
changes to our forecast.

About PeptiDream Inc.
PeptiDream Inc. (Tokyo Stock Exchange Prime Section 4587) is leading the translation of macrocyclic
peptides into a whole new class of innovative medicines to address unmet medical needs and improve
the quality of life of patients worldwide. In its radiopharmaceutical business, through its wholly-owned
subsidiary PDRadiopharma, PeptiDream markets and sells a number of approved
radiopharmaceuticals and radiodiagnostics in Japan, as well as leveraging its proprietary Peptide
Discovery Platform System (PDPS®) technology to discover and develop a deep pipeline of innovative

targeted radiotherapeutics and radiodiagnostics, spanning both wholly-owned internal programs and
globally partnered programs. In its non-radiopharmaceutical business, PeptiDream is similarly
leveraging PDPS to discover and develop a broad and diverse pipeline of investigational peptide
therapeutics, peptide drug conjugates (PDC) and multi-functional peptide conjugates (MPC) across an
extensive global network of discovery and development partners. PeptiDream is headquartered in
Kawasaki, Japan. For more information about our company, science and pipeline, please visit
www.peptidream.com/en/

Inquiries:

PeptiDream Inc.
Contact: Yuko Okimoto, IR & Corporate Communications
Email: [email protected]
Website: https://www.peptidream.com/en/
IR updates subscription: https://www.peptidream.com/en/ir/mail/
X: https://x.com/PeptidreamInc
LinkedIn: https://www.linkedin.com/company/peptidream