Agomab reports positive Phase 1 IPF trial data

Agomab advances inhaled IPF candidate AGMB-447 from supportive Phase 1 data toward a 24-week Phase 2 INSPIRIA trial planned to start in 2026.

Rhea-AI Filing Summary

Agomab Therapeutics NV (AGMB) reported positive Phase 1 results for its inhaled ALK5 inhibitor AGMB-447 in patients with idiopathic pulmonary fibrosis (IPF) and described the design of the Phase 2 INSPIRIA study. In 10 IPF patients, AGMB-447 showed a generally favorable safety and tolerability profile at 4.5 mg twice daily, with low systemic and high lung exposure and no systemic safety signals detected. Target engagement was demonstrated by >50% reduction of pSMAD3 in bronchoalveolar lavage cells. Agomab has submitted a Clinical Trial Application for INSPIRIA, a 24-week randomized, double-blind, placebo-controlled Phase 2 trial in approximately 120 IPF patients, with change in forced vital capacity at Week 24 as the primary endpoint and trial initiation anticipated in the second half of 2026.

Positive

• Phase 1 data support further development: In 10 IPF patients, AGMB-447 at 4.5 mg BID showed a generally favorable safety and tolerability profile, lung-restricted pharmacokinetics with low systemic exposure, and >50% pSMAD3 reduction indicating robust ALK5 target engagement.
• Phase 2 INSPIRIA trial progressing: The Clinical Trial Application has been submitted for a 24-week, ~120-patient randomized, double-blind, placebo-controlled Phase 2 IPF study, with forced vital capacity at Week 24 as the primary endpoint and initiation anticipated in the second half of 2026.

Negative

• Clinical program remains early stage: Phase 1 included only 10 IPF patients, AGMB-447 is still investigational, not approved by any regulatory authority, and its efficacy and safety have not been established.
• High unmet need and severe disease context: IPF affects about 255,000 patients in major markets, with a median survival of only 3–5 years despite three approved therapies that slow but do not halt disease progression.

Filing Explained

The September 14, 2026 filing adds a dose-specific limitation: adverse events were more frequent at 6 mg twice daily than at 4.5 mg, although no new specific safety issue or systemic safety issue was identified. AGMB-447 remains investigational, is not approved, and its efficacy and safety have not been established.

Key Figures

IPF patients in Phase 1 Part C: 10 patients AGMB-447 dosing in IPF patients (Part C): 4.5–6 mg twice daily pSMAD3 reduction at 4.5 mg BID: >50% +5 more

8 metrics

IPF patients in Phase 1 Part C 10 patients Multiple dose AGMB-447 study in IPF patients (Part C) of Phase 1

AGMB-447 dosing in IPF patients (Part C) 4.5–6 mg twice daily Multiple dose nebulized AGMB-447 over 14 days in IPF patients

pSMAD3 reduction at 4.5 mg BID >50% Reduction in bronchoalveolar lavage cells indicating robust ALK5 target engagement

INSPIRIA Phase 2 duration 24 weeks Planned duration of randomized, double-blind, placebo-controlled Phase 2 IPF study

INSPIRIA planned enrollment Approximately 120 patients IPF patients randomized 2:1 to AGMB-447 4 mg BID or placebo

AGMB-447 Phase 2 dose 4 mg twice daily Dose to be administered by inhalation on top of standard of care

Approximate IPF prevalence 255,000 patients IPF patients in the U.S., Japan and largest European markets (EU4+UK)

IPF median survival after diagnosis 3–5 years Median survival without lung transplant despite three approved therapies

Key Terms

Idiopathic Pulmonary Fibrosis, bronchoalveolar lavage, forced vital capacity, Clinical Trial Application, +2 more

6 terms

Idiopathic Pulmonary Fibrosis medical

"AGMB-447 is intended for the treatment of Idiopathic Pulmonary Fibrosis (IPF)."

Idiopathic pulmonary fibrosis is a chronic lung disease in which the air‑carrying tissue becomes progressively thickened and scarred for no identifiable reason, making the lungs stiff and less able to move oxygen—similar to a sponge that hardens and loses its pores. It matters to investors because it is life‑limiting with limited effective treatments, so clinical trial outcomes, regulatory approvals, pricing and reimbursement decisions can strongly affect the commercial value of therapies and the financial prospects of companies developing treatments.

bronchoalveolar lavage medical

"daily doses of 4.5 mg BID achieved average bronchoalveolar lavage fluid levels"

A bronchoalveolar lavage is a medical procedure that rinses a small area of the lung with fluid and then collects that fluid for analysis, like flushing and examining the inside of a pipe to see what’s inside. Investors care because results can reveal infection, inflammation, or drug-related lung effects that influence clinical trial outcomes, regulatory decisions and market perception of respiratory therapies or safety profile of systemic drugs.

forced vital capacity medical

"The primary endpoint will be the change from baseline in forced vital capacity"

The amount of air a person can forcefully breathe out after taking the deepest breath possible; think of it as how much air you can squeeze out of a balloon in one hard blow. It matters to investors because it’s a common, objective measure used in clinical trials and patient monitoring for respiratory drugs, devices and treatments—changes in this number can signal whether a therapy works, affecting regulatory approval, sales and company value.

Clinical Trial Application regulatory

"Clinical Trial Application (CTA) for INSPIRIA Phase 2 study in IPF patients submitted"

An application submitted to a regulatory authority requesting formal permission to begin testing a new drug, medical device, or treatment in humans. Like asking for a building permit before construction, it summarizes safety data, plans for how the study will be run, and monitoring procedures; investors watch these filings closely because approval lets a program move from lab research to clinical testing, reducing uncertainty and creating value-driving milestones.

ALK5 medical

"AGMB-447 is an inhaled lung-restricted small molecule inhibitor of ALK5"

A receptor protein on cell surfaces that receives signals from the TGF‑β pathway and helps control cell growth, scarring and inflammation. Think of it like a traffic signal that tells cells to slow down, change behavior or produce scar tissue; drugs that block or tweak ALK5 can alter those signals, so progress in ALK5-targeting drugs can materially affect the prospects and value of biotech firms developing treatments for fibrosis, cancer, or related conditions.

TGFβ/ALK5 pathway medical

"by blocking the TGFβ/ALK5 pathway locally in the lung, AGMB-447 has the potential"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Agomab Therapeutics (AGMB) report about AGMB-447 in this 6-K?

Agomab reported positive Phase 1 results for AGMB-447 in IPF patients, showing a generally favorable safety, tolerability and lung-restricted pharmacokinetic profile with robust ALK5 target engagement, and outlined the planned Phase 2 INSPIRIA study design.

How many IPF patients were included in Agomab’s Phase 1 AGMB-447 study?

Part C of the Phase 1 program included 10 IPF patients who received AGMB-447 doses between 4.5 mg and 6 mg twice daily by nebulization over a 14-day dosing period.

What is the planned design of the Phase 2 INSPIRIA trial for AGMB-447 in IPF?

INSPIRIA is a 24-week, randomized, double-blind, placebo-controlled Phase 2 study in approximately 120 IPF patients, randomized 2:1 to AGMB-447 4 mg twice daily or placebo on top of standard of care.

What is the primary endpoint of the INSPIRIA Phase 2 study for AGMB-447?

The primary endpoint of INSPIRIA is the change from baseline in forced vital capacity at Week 24, assessing lung function in IPF patients receiving AGMB-447 or placebo in addition to standard of care.

When does Agomab (AGMB) expect to start the INSPIRIA Phase 2 trial?

Agomab states that the Clinical Trial Application has been submitted and the INSPIRIA Phase 2 IPF study is anticipated to begin in the second half of 2026 across a large European site network.

What safety and pharmacokinetic findings were observed for AGMB-447 in IPF patients?

At 4.5 mg twice daily, AGMB-447 showed a generally favorable safety and tolerability profile. Low systemic but high pulmonary exposure supported its lung-restricted pharmacokinetic profile, with cough and bronchospasm as the most frequent adverse events.

How large is the IPF patient population addressed by Agomab’s AGMB-447 program?

Idiopathic pulmonary fibrosis affects approximately 255,000 patients in the U.S., Japan and the largest European markets, with a median survival of only 3–5 years after diagnosis despite currently approved therapies.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/14/2026 - 04:15 PM Accepted by SEC EDGAR 09/14/2026 - 04:14 PM Learn about SEC filing dates

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of September 2026

Commission File Number: 001-43098

AgomAb Therapeutics NV

Posthoflei 1/6

2600 Antwerpen

Belgium

Tel: +32 3 318 91 70

(Address, Including Zip Code, and Telephone Number,

Including Area Code, of Registrant’s Principal Executive Offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F x Form 40-F ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ¨

On September 14, 2026, AgomAb Therapeutics NV (the “Company”) issued a press release titled, “Agomab Announces Positive Phase 1 Results for AGMB-447 in Patients with Idiopathic Pulmonary Fibrosis and Design of Phase 2 INSPIRIA Study.” A copy of this press release is attached hereto as Exhibit 99.1 and incorporated herein by reference.

The information contained in this Form 6-K, including Exhibit 99.1, except for the quotes by Philippe Wiesel, Chief Medical Officer, and Toby Maher, M.D., PhD, Professor of Clinical Medicine at Keck School of Medicine of USC, is hereby incorporated by reference into the Company’s Registration Statement on Form S-8 (File No. 333-294220).

INDEX TO EXHIBITS

Number		Description
99.1		Press Release of AgomAb Therapeutics NV dated September 14, 2026, titled  “Agomab Announces Positive Phase 1 Results for AGMB-447 in Patients with Idiopathic Pulmonary Fibrosis and Design of Phase 2 INSPIRIA Study.”

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	AgomAb Therapeutics NV
Date: September 14, 2026	By:	/s/ Tim Knotnerus
		Tim Knotnerus
		Chief Executive Officer

Exhibit 99.1

 

Agomab Announces Positive Phase 1 Results for AGMB-447 in Patients with Idiopathic Pulmonary Fibrosis and Design of Phase 2 INSPIRIA Study

-- Topline Phase 1 data shows generally favorable safety and tolerability profile of AGMB-447 --

-- Pharmacokinetic profile confirms efficient lung restriction with low systemic exposure and high exposure of AGMB-447 in the lung, in line with prior results observed in healthy participants --

-- Robust target engagement of ALK5 observed with AGMB-447 in IPF patients --

-- Clinical Trial Application (CTA) for INSPIRIA Phase 2 study in IPF patients submitted; Company

intends to initiate study before year-end --

Antwerp, Belgium, September 14, 2026 – Agomab Therapeutics NV (‘Agomab’), a clinical-stage biopharmaceutical company focused on fibro-inflammation, today announced positive results of the Phase 1 study of AGMB-447 in IPF patients. AGMB-447 is an investigational inhaled lung-restricted small molecule inhibitor of ALK5 (or TGFβR1) intended for the treatment of Idiopathic Pulmonary Fibrosis (IPF).¹

The Phase 1 study of AGMB-447 is a three-part, double-blind, randomized, placebo-controlled single ascending dose (SAD; Part A; dose range: 1 mg QD (once daily) to 20 mg QD) and multiple ascending dose (MAD; Part B; dose range: 1 mg QD to 6 mg BID (twice daily)) study in healthy participants and multiple dose study in IPF patients (Part C; dose range: 4.5 mg BID to 6 mg BID). AGMB-447 was administered via nebulization, as a single dose in the SAD, over seven days in Part B and over 14 days in Part C.

A total of 10 IPF patients were included in Part C. In line with the data in healthy participants reported previously, AGMB-447 was observed to have a generally favorable safety and tolerability profile in IPF patients at 4.5 mg BID. While a higher incidence of adverse events was reported at 6 mg BID, no new specific safety signals were identified, and no systemic safety signals were detected at any dose. The most frequently reported adverse events were cough and bronchospasm. Cough episodes were short and mostly limited to the inhalation period. Furthermore, no increase in the severity of disease-related cough was reported at any dose over the 14-day dosing period.

Low systemic but high pulmonary exposure of AGMB-447 was also measured in IPF patients, supporting its lung-restricted pharmacokinetic (PK) profile. In IPF patients, daily doses of 4.5 mg BID achieved average bronchoalveolar lavage (BAL) fluid levels above IC₉₀ for at least 6 hours post-inhalation, and above IC₅₀ for 24 hours, in line with the PK profile observed in healthy participants.

In IPF patients, pSMAD3 reduction in BAL cells of >50% was achieved at the 4.5 mg BID dose, indicating robust target engagement in line with the results observed previously in healthy participants and supporting further clinical development of AGMB-447 for the treatment of IPF.

¹ Study Details | Phase I Study to Assess Safety, Tolerability, PK and PD of AGMB-447 in Healthy Participants and Participants With IPF | ClinicalTrials.gov

 

“We are very pleased with the Phase 1 results of AGMB-447 in patients with IPF announced today. In line with the positive interim data in healthy participants announced earlier this year, the data indicated a generally favorable safety, tolerability and PK profile of AGMB-447 and provided proof-of-mechanism of TGFβ/ALK5 inhibition in the lungs of IPF patients,” said Philippe Wiesel, Chief Medical Officer at Agomab. “We believe that by blocking the TGFβ/ALK5 pathway locally in the lung, AGMB-447 has the potential to offer a potent anti-fibrotic therapy to IPF patients. The extensive data collected in our broad Phase 1 program supports the initiation of our Phase 2 INSPIRIA study later this year.”

The company also announced the design of INSPIRIA, its planned Phase 2 study with AGMB-447 in IPF. INSPIRIA is a 24-week Phase 2, randomized, double-blind, placebo-controlled study in approximately 120 patients with confirmed IPF. Patients will be randomized 2:1 to receive AGMB-447 4 mg twice daily or placebo, administered by inhalation on top of standard of care. The study is designed to evaluate the safety, pharmacokinetics and efficacy of AGMB-447 in IPF patients. The primary endpoint will be the change from baseline in forced vital capacity at Week 24. The CTA for INSPIRIA has been submitted, and the study is anticipated to begin in the second half of 2026 across a large European site network.

“We have long known that the TGFβ pathway is a central driver of fibrosis in IPF. Targeting this key pathway through ALK5 inhibition with AGMB-447 is a promising approach. With a convenient twice-daily dosing schedule, AGMB-447 could represent an attractive option for monotherapy or combination therapy with systemic standard of care therapies. The INSPIRIA study is designed to further explore the therapeutic potential of this novel inhaled approach in people living with IPF,” said Toby Maher, M.D., PhD, Professor of Clinical Medicine at Keck School of Medicine of USC.

Agomab intends to present detailed Phase 1 results at a future scientific conference.

AGMB-447 is an investigational drug and not approved by any regulatory authority. Its efficacy and safety have not been established. 

About IPF

Idiopathic Pulmonary Fibrosis (IPF) is a devastating disease affecting approximately 255,000 patients in the U.S., Japan, and the largest European markets (EU4+UK). IPF is characterized by unregulated production of fibrotic, scar-like tissue that builds up in the scaffolding of the lungs. As a result, the fibrotic lung becomes stiff, hampers the patient’s ability to breathe and reduces the absorption of inhaled oxygen in the blood. Despite the commercial availability of three approved therapies, without a lung transplant, the median survival following diagnosis is only 3-5 years. Moreover, these therapies do not halt but only slow down disease progression and have side effects that reduce tolerability and lead to treatment discontinuations.

About AGMB-447

AGMB-447 is an inhaled lung-restricted small molecule inhibitor of ALK5 (or TGFβR1) intended for the treatment of Idiopathic Pulmonary Fibrosis (IPF). TGFβ is the master regulator of fibrosis, which is the key mechanism driving IPF disease progression. AGMB-447 is specifically designed to inhibit ALK5 in the lung while avoiding clinically relevant systemic exposure through local administration via inhalation and rapid hydrolyzation in plasma into one main metabolite inactive in cells. Through AGMB-447, Agomab aims to offer a potentially safe and effective novel anti-fibrotic therapeutic option to IPF patients.

 

About Agomab

Agomab is a clinical-stage biopharmaceutical company focused on developing novel disease-modifying therapies for fibro-inflammatory diseases with high unmet medical need. Agomab’s product candidates are designed to target established, potent pathways and utilize organ-restricted approaches, with the aim of increasing efficacy while minimizing safety liabilities. Fostering a culture of excellence, Agomab’s mission is to pioneer therapeutics that aim to resolve fibro-inflammation and restore organ function to enable people with these disorders to live fuller and healthier lives.

Cautionary Note regarding Forward-Looking Statements

This press release includes certain disclosures that contain "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements are often identified by terms such as "continue," "anticipate," "believe," "could," "estimate," "expect," "goal," "intend," "look forward to," "may," "plan," "potential," "predict," "project," "should," "will," "would" and similar expressions. “Forward-looking statements” include, without limitation, statements regarding the potential of AGMB-447 for the treatment of IPF, the design of the planned Phase 2 clinical trial with AGMB-447 for IPF, our expectation to initiate our Phase 2 clinical trial of AGMB-447 in IPF in the second half of 2026, and our interactions with regulatory authorities. Forward-looking statements are based on Agomab’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict. Factors that could cause actual results to differ include, but are not limited to, risks and uncertainties related to the results of our clinical trials; expectations regarding the inherent uncertainties associated with the development of novel drug therapies; preclinical and clinical trial and product development activities and regulatory approval requirements for product candidates; the impact of governmental laws and regulations on our business; and disruptions caused by our reliance on third party suppliers and service providers. These and other risks and uncertainties are described more fully in our filings and reports with the SEC, including in our most recent annual report on Form 20-F filed with the SEC and our subsequent filings and reports filed with the SEC. Forward-looking statements contained in this announcement are made as of this date, and Agomab undertakes no duty to update such information except as required under applicable law. Readers should not rely upon the information in this announcement as current or accurate after its publication date.

Contacts

Investors

Sofie Van Gijsel

VP of Investor Relations

E-Mail: sofie.vangijsel@agomab.com

Phone: +1 781 296 1143

Media

Gretchen Schweitzer

Trophic Communications

E-Mail: agomab@trophic.eu

Phone: +49 172 861 8540

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 EXHIBIT 99.1 20.9 KB