Protagonist Announces Presentation of One-Year Phase 3 Data for ICOTYDE(TM) in Moderate-to-Severe Plaque Psoriasis at the 2026 American Academy of Dermatology (AAD) Annual Meeting

NEWARK, Calif., March 28, 2026 (Newswire.com) - Protagonist Therapeutics, Inc. (Nasdaq:PTGX) ("Protagonist" or "the Company") today announced new one-year Phase 3 results for ICOTYDE^™ (icotrokinra) were presented at the 2026 American Academy of Dermatology (AAD) Annual Meeting. Data from the Phase 3 ICONIC-ADVANCE 1 and 2 and ICONIC-LEAD studies further support the potential of ICOTYDE as a differentiated oral therapy for patients with moderate-to-severe plaque psoriasis.

"The one-year Phase 3 results presented at AAD reinforce our belief that ICOTYDE by virtue of having IL-23 antagonist efficacy, a favorable safety profile and the convenience of a once-daily oral pill option, has the potential to meaningfully expand treatment options for people living with moderate-to-severe plaque psoriasis," said Dinesh V. Patel, Ph.D., President and Chief Executive Officer of Protagonist Therapeutics. "These findings highlight the power of Protagonist's peptide discovery platform and our ability to create highly differentiated oral medicines against clinically validated biological pathways."

ICOTYDE is the first and only targeted oral peptide designed to precisely block the IL-23 receptor, which underpins the inflammatory response in moderate-to-severe plaque PsO.

ICOTYDE was developed using Protagonist's proprietary peptide technology platform. The Company continues to invest in its discovery engine and development pipeline, with multiple programs moving towards proof-of-concept trials designed to produce therapeutics with clinically relevant competitive differentiation.

Under the license and collaboration agreement established in 2017 between Protagonist and Janssen Biotech, Inc., a Johnson & Johnson company, Johnson & Johnson is responsible for all commercial activities for ICOTYDE. ICOTYDE was jointly discovered by Protagonist and Johnson & Johnson scientists, with Protagonist having primary responsibility for the development of ICOTYDE through Phase 1, and Johnson & Johnson assuming responsibility for further development and commercialization.

ICONIC-ADVANCE 1 & ICONIC-ADVANCE 2

ICOTYDE demonstrated durable rates of complete skin clearance through Week 52 with no new safety signals identified. Rates of PASI 100 increased from Week 24 to Week 52 in the ICOTYDE treatment arms, and patients who switched from placebo to ICOTYDE at Week 16 achieved similar rates of complete skin clearance by Week 52 as those treated with ICOTYDE continuously for 52 weeks. The ICOTYDE adverse event profile through Week 52 was consistent with that observed through Weeks 16 and 24, and no new safety signal was identified through Week 52. ICOTYDE overall adverse event and infection rates were lower than deucravacitinib through Week 24.

ICONIC-LEAD

ICOTYDE also demonstrated sustained efficacy and a favorable safety profile in adolescents through Week 52. Nearly 60% of adolescents treated with ICOTYDE achieved completely clear skin at one year, and 86% achieved PASI 90, with 92% maintaining that response from Week 24 to Week 52. No new safety signals were identified over one year of treatment.

The pivotal ICONIC Phase 3 clinical development program includes five studies in plaque psoriasis: ICONIC-LEAD, ICONIC-TOTAL, ICONIC-ADVANCE 1, ICONIC-ADVANCE 2, and ICONIC-ASCEND. Additional studies are also underway in psoriatic arthritis, ulcerative colitis, and Crohn's disease.

Under Protagonist's collaboration agreement with Johnson & Johnson, the Company is eligible to receive tiered royalties on net sales of ICOTYDE and additional future milestone payments. Protagonist believes the continued advancement of ICOTYDE highlights the strength of its oral peptide platform and its strategy of creating potentially best-in-class medicines through internal innovation and strategic partnerships.

About ICOTYDE^™ (icotrokinra)

ICOTYDE (icotrokinra) is the first and only targeted oral peptide designed to precisely block the IL-23 receptor, which underpins the inflammatory response in moderate-to-severe plaque PsO. ICOTYDE binds to the IL-23 receptor with high affinity and demonstrated potent inhibition of IL-23 signaling in human T cells. Clinical significance of these findings are unknown.

ICOTYDE is currently approved in the U.S. for the treatment of adults, and pediatric patients 12 years of age and older who weigh at least 40 kg, with moderate-to-severe plaque PsO who are candidates for systemic therapy or phototherapy. Patients on ICOTYDE take one pill, once a day with water upon waking, 30 minutes prior to eating food.

ICOTYDE is also currently in Phase 3 studies for active psoriatic arthritis, moderately to severely active ulcerative colitis and moderately to severely active Crohn's disease.

ICOTYDE was jointly discovered by Protagonist and Johnson & Johnson scientists and is being developed and commercialized by Johnson & Johnson. The approval of ICOTYDE triggers a $50 million milestone payment to Protagonist. Protagonist is also eligible for 6 - 10% upward tiering royalties on worldwide net sales, as well as additional regulatory and sales milestone payments of up to $580 million.

About Plaque Psoriasis
Plaque psoriasis (PsO) is a chronic immune-mediated disease resulting in overproduction of skin cells, which causes inflamed, scaly plaques that may be itchy or painful. It is estimated that 8 million Americans and more than 125 million people worldwide live with the disease. Nearly one-quarter of all people with plaque PsO have cases that are considered moderate-to-severe. On Caucasian skin, plaques typically appear as raised, red patches covered with a silvery white buildup of dead skin cells or scale. On skin of color, the plaques may appear darker and thicker, and more of a purple, gray, or dark brown color. Plaques can appear anywhere on the body, although they most often appear on the scalp, knees, elbows, and torso. Living with plaque PsO can be a challenge and impact life beyond a person's physical health, including emotional health, relationships, and handling the stressors of life. Psoriasis on highly visible areas of the body or sensitive skin, such as the scalp, hands, feet, and genitals, can have an increased negative impact on quality of life.

About Protagonist

Protagonist Therapeutics is a discovery through late-stage development biopharmaceutical company. The Company's proprietary peptide technology platform enables de novo discovery of peptide therapeutics. Two novel peptides derived from Protagonist's proprietary discovery platform are at or near commercialization. ICOTYDE^™ (icotrokinra) is approved in the U.S. for the treatment of moderate-to-severe plaque psoriasis in adults and pediatric patients 12 years of age and older who weigh at least 40 kg who are candidates for systemic therapy or phototherapy. ICOTYDE is the first and only targeted oral peptide that precisely blocks the Interleukin-23 receptor (IL-23R) licensed to Janssen Biotech, Inc., a Johnson & Johnson company. ICOTYDE was jointly discovered by Protagonist and Johnson & Johnson scientists, with Protagonist having primary responsibility for the development of ICOTYDE through Phase 1, and Johnson & Johnson assuming responsibility for further development and commercialization. An NDA for rusfertide, a first-in-class hepcidin mimetic peptide that is being co-developed with Takeda Pharmaceuticals pursuant to a worldwide license and collaboration agreement entered in 2024, is under priority review with the FDA. Protagonist holds an option to co-commercialize rusfertide in the U.S. through a 50/50 profit and loss share structure or can opt-out of this structure. The Company also has a number of preclinical stage drug discovery programs addressing clinically and commercially validated targets including an oral IL-17 peptide antagonist, obesity dual and triple agonists, an oral hepcidin functional mimetic, and the recently announced IL-4 and amylin programs.

More 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 ICOTYDE and potential revenue from the Company's collaboration with Johnson & Johnson. 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

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ICOTYDE^™ INDICATION AND IMPORTANT SAFETY INFORMATION
What is the most important information I should know about ICOTYDE?

• Infections. Medicines that interact with the immune system, such as ICOTYDE, may lower your ability to fight infections and may increase your risk of infections. Your healthcare provider may check you for infections and tuberculosis (TB) before starting treatment and may treat you for TB before you begin treatment with ICOTYDE if you have a history of TB or have active TB. Your healthcare provider should watch you closely for signs and symptoms of TB during and after treatment with ICOTYDE.

Before taking ICOTYDE, tell your healthcare provider about all of your medical conditions, including if you:

• have an infection that does not go away or that keeps coming back.

• have tuberculosis (TB) or have been in close contact with someone with TB.

• have recently received or are scheduled to receive an immunization (vaccine). Avoid receiving live vaccines during treatment with ICOTYDE.

• have kidney problems.

• are pregnant or plan to become pregnant. It is not known if ICOTYDE can harm your unborn baby.

Pregnancy Safety Study. There is a pregnancy safety study for women who take ICOTYDE during pregnancy. The purpose of this study is to collect information about the health of you and your baby. If you are pregnant or become pregnant during treatment with ICOTYDE, you can report your pregnancy by calling 1-800-526-7736 or visiting www.ICOTYDE.com.

• are breastfeeding or plan to breastfeed. It is not known if ICOTYDE passes into your breast milk. Talk to your healthcare provider about the best way to feed your baby during treatment with ICOTYDE.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

What are the possible side effects of ICOTYDE?

ICOTYDE may cause serious side effects. See "What is the most important information I should know about ICOTYDE?"

The most common side effects of ICOTYDE include:

These are not all the possible side effects of ICOTYDE. Call your doctor for medical advice about side effects. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

How should I take ICOTYDE?

• Take ICOTYDE exactly as your healthcare provider tells you to take it.

• Take ICOTYDE 1 time a day when you wake up on an empty stomach with water. Wait at least 30 minutes after taking ICOTYDE before eating food.

• If you have difficulty swallowing tablets, ICOTYDE can be dispersed in water. For more information, please read the Medication Guide.

• If you miss a dose of ICOTYDE, take the dose as soon as you remember and go back to your regular schedule the next day.

Please read the full Prescribing Information, including Medication Guide, for ICOTYDE and discuss any questions that you have with your doctor.

SOURCE: Protagonist Therapeutics

Source: Protagonist Therapeutics