Protagonist Reports Third Quarter 2025 Financial Results and Provides Corporate Update Following the NDA submission for icotrokinra treatment of adults and adolescents with moderate to severe plaque psoriasis to the U.S.

Protagonist Reports Third

Quarter 2025 Financial Results and Provides Corporate Update

Following the NDA submission

for icotrokinra treatment of adults and adolescents with moderate to severe plaque psoriasis to the U.S. FDA in July, the European Medicines

Agency (EMA) application was submitted in September

breakthrough designation for patients in Polycythemia Vera (PV) and the subject of four presentations including 52-week results of the

VERIFY Phase 3 Study at ASH, the 67th Annual American Society of Hematology (ASH) meeting in December

in the Phase 1 trial of PN-881, a first-in-class oral IL-17 peptide antagonist

IND-enabling studies

progressing as planned with triple-GLP/GIP/GCG agonists PN-477sc and PN-477o

Oral hepcidin development

candidate expected to be nominated by year end

Cash, cash equivalents

and marketable securities of $678.8 million as of September 30, 2025, anticipated to provide cash runway through at least end of

Calif., November 6, 2025 - Protagonist Therapeutics (Nasdaq: PTGX) ("Protagonist"

or "the Company") today reported financial results for the third quarter ended September 30, 2025, and provided a corporate

"2025 continues to be a highly productive

year with significant accomplishments in both partnered and wholly owned programs," said Dinesh V. Patel, Ph.D., the Company's

President and CEO. "In addition to the NDA and EMA submissions for icotrokinra for psoriasis, we are pleased to see our partner

Johnson and Johnson expand the ICONIC program into additional IL-23 pathway relevant and validated I&I indications, namely psoriatic

arthritis, ulcerative colitis, and Crohn's disease. We, along with our partner Takeda, eagerly await the presentation of

the rusfertide 52-week VERIFY data at ASH in December and the NDA filing for rusfertide by year end."

"As icotrokinra and rusfertide move towards potential NDA

approval and commercialization in 2026, we shift our attention to the next phase of assets emerging from our validated

discovery and development platform. We are pleased to report that the first subject in the Phase 1 trial of oral IL-17

antagonist, PN-881, is dosed. Additionally, the oral and subcutaneous triple GLP/GIP/GCG agonists, PN-477o and PN-477sc, are

progressing through IND-enabling studies as planned, and we remain on track to nominate a development candidate from the oral

hepcidin program by year end. I am very proud of the consistent innovation and execution capabilities of the Protagonist

Quarter 2025 Recent Developments and Upcoming Milestones

Oral IL-23 Receptor Antagonist

Rusfertide: Subcutaneous Injectable

Hepcidin Mimetic for Polycythemia Vera (PV) and Other Blood Disorders

Discovery and Development Pipeline

Third Quarter 2025 Financial Results

Protagonist Therapeutics is a discovery through late-stage development

biopharmaceutical company. Two novel peptides derived from Protagonist's proprietary discovery platform are currently in advanced Phase

3 clinical development, with a New Drug Application (NDA) for icotrokinra submitted to the FDA in July, and the NDA submission for rusfertide

expected by end of 2025. Icotrokinra (formerly, JNJ-2113), is a first-in-class investigational targeted oral peptide that selectively

blocks the Interleukin-23 receptor ("IL-23R"), which is licensed to Janssen Biotech, Inc., a Johnson & Johnson

company. Following icotrokinra's joint discovery by Protagonist and Johnson & Johnson scientists pursuant to the companies' IL-23R

collaboration, Protagonist was primarily responsible for the development of icotrokinra through Phase 1, with Johnson & Johnson

assuming responsibility for development in Phase 2 and beyond. Rusfertide, a mimetic of the natural hormone hepcidin, is currently in

Phase 3 development for the rare blood disorder polycythemia vera (PV). Rusfertide is being co-developed and will be co-commercialized

with Takeda Pharmaceuticals pursuant to a worldwide collaboration and license agreement entered in 2024 under which the Company remains

primarily responsible for development through NDA filing. The Company also has a number of preclinical stage drug discovery programs addressing

clinically and commercially validated targets, including IL-17 oral peptide antagonist PN-881, obesity triple agonist peptide PN-477,

and the oral hepcidin program.

information on Protagonist, its pipeline drug candidates, and clinical studies can be found on the Company's website at https://www.protagonist-inc.com.

Cautionary Note on Forward-Looking Statements

This press release contains forward-looking statements for purposes

of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include statements regarding

the potential benefits of icotrokinra and PN-881, and expectations regarding the icotrokinra and PN-881 development programs. In some

cases, you can identify these statements by forward-looking words such as "anticipate," "believe," "may,"

"will," "expect," or the negative or plural of these words or similar expressions. Forward-looking statements are

not guarantees of future performance and are subject to risks and uncertainties that could cause actual results and events to differ materially

from those anticipated, including, but not limited to, our ability to develop and commercialize our product candidates, our ability to

earn milestone payments under our collaboration agreements with Janssen and Takeda, our ability to use and expand our programs to build

a pipeline of product candidates, our ability to obtain and maintain regulatory approval of our product candidates, our ability to operate

in a competitive industry and compete successfully against competitors that have greater resources than we do, and our ability to obtain

and adequately protect intellectual property rights for our product candidates. Additional information concerning these and other risk

factors affecting our business can be found in our periodic filings with the Securities and Exchange Commission, including under the heading

"Risk Factors" contained in our most recently filed periodic reports on Form 10-K and Form 10-Q filed with the Securities

and Exchange Commission. Forward-looking statements are not guarantees of future performance, and our actual results of operations, financial

condition, and liquidity, and the development of the industry in which we operate, may differ materially from the forward-looking statements

contained in this press release. Any forward-looking statements that we make in this press release speak only as of the date of this press

release. We assume no obligation to update our forward-looking statements, whether as a result of new information, future events, or otherwise,

after the date of this press release.

Investor Relations Contact

Media Relations Contact

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PROTAGONIST THERAPEUTICS, INC.

Condensed Consolidated Statements of Operations

(Amounts in thousands except share and per share

includes non-cash stock-based compensation expense.

(Unaudited, in thousands)

PROTAGONIST THERAPEUTICS, INC.

Selected Condensed Consolidated Balance Sheet

(Unaudited, In thousands)