Low reactive metabolite data support InflaRx (IFRX) oral C5aR1 drug

Rhea-AI Filing Summary

InflaRx N.V. reported new preclinical data showing its oral C5aR1 inhibitor izicopan generated low levels of reactive metabolites in a head-to-head in vitro study using human liver microsomes. In a glutathione trapping assay at 10 µM over 0–40 minutes, izicopan’s conjugate levels remained low, suggesting limited bioactivation in this experimental setting.

Under the same conditions, the marketed C5aR1 inhibitor avacopan produced higher levels of thiol adducts, with total reactive conjugate peak areas exceeding 100-fold those of izicopan at 5 and 10 minutes and about 10-fold at 20 and 40 minutes. InflaRx highlights these findings, together with prior Phase 1 and Phase 2a data and ≥90% C5a-induced neutrophil activation blockade over 14 days, as supporting izicopan’s differentiated profile, while emphasizing that in vitro results do not directly predict clinical outcomes.

Key Figures

Microsome assay concentration: 10 µM Microsome assay duration: 0–40 minutes Early reactive conjugate difference: >100-fold +5 more

8 metrics

Microsome assay concentration 10 µM Glutathione trapping assay in human liver microsomes

Microsome assay duration 0–40 minutes Incubation period for izicopan vs avacopan

Early reactive conjugate difference >100-fold Avacopan vs izicopan at 5 and 10 minutes

Later reactive conjugate difference ≈10-fold Avacopan vs izicopan at 20 and 40 minutes

Single-dose range 3–240 mg First-in-human izicopan study dose range

Multiple-dose regimens 30 mg QD to 90 mg BID Izicopan dosing for 14 days in human study

C5a-induced neutrophil blockade ≥90% Maintained over 14-day dosing period

Therapy duration in HS study 4 weeks Izicopan treatment period in hidradenitis suppurativa

Key Terms

reactive metabolite formation, glutathione (GSH) trapping assay, C5aR1 inhibitor, cytochrome P450 3A4 (CYP3A4), +2 more

6 terms

reactive metabolite formation medical

"announced new preclinical data demonstrating low reactive metabolite formation of izicopan"

glutathione (GSH) trapping assay medical

"in a head-to-head in vitro study using a standard glutathione (GSH) trapping assay"

A glutathione (GSH) trapping assay is a laboratory test that checks whether a chemical binds to or is altered by glutathione, a natural molecule cells use to neutralize harmful compounds. Think of it as dropping a substance into a sponge that represents the body’s detox system to see if the sponge soaks it up or changes it; results signal potential safety problems, metabolic instability, or regulatory hurdles that investors use to judge a drug or chemical’s risk and development value.

C5aR1 inhibitor medical

"izicopan, a next-generation oral C5aR1 inhibitor, in human liver microsomes"

cytochrome P450 3A4 (CYP3A4) medical

"in vitro experiments demonstrated that izicopan does not inhibit the cytochrome P450 3A4 (CYP3A4) enzyme"

A liver enzyme that acts like the body’s chemical “processing plant,” breaking down many prescription drugs, hormones and other compounds so they can be cleared from the body. Investors care because how strongly a drug interacts with this enzyme affects dosing, safety, potential side effects and whether two drugs can be safely combined, all of which influence clinical trial outcomes, regulatory approval and commercial value.

hidradenitis suppurativa medical

"In patients with hidradenitis suppurativa, over 4 weeks of therapy, izicopan provided rapid and clinically meaningful reductions"

A chronic skin disease marked by recurring, painful lumps and tunnels under the skin that often leak and leave scars; it behaves like a slow-burning, recurring infection in areas with many sweat glands. For investors, it matters because the condition has few consistently effective treatments and causes long-term healthcare use, making successful new drugs, devices, or diagnostics potentially high-value opportunities while also carrying clinical-trial, regulatory and reimbursement risks.

chronic spontaneous urticaria medical

"In chronic spontaneous urticaria, InflaRx observed substantial reductions in the 7-day Urticaria Activity Score"

A long-term condition that causes recurring, itchy hives and sometimes swelling that appear without a clear trigger, like an alarm that goes off unpredictably on its own. It matters to investors because its chronic nature creates ongoing demand for treatments, diagnostics and follow-on care, influencing pharmaceutical research priorities, drug market size, regulatory review timelines and healthcare cost projections.

Form 6-K: How Foreign Companies Report to the SEC →

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 May 2026

Commission File

Number: 001-38283

InflaRx N.V.

Winzerlaer Str. 2

07745 Jena,

Germany

(+49) 3641508180

(Address of 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 ☒ Form 40-F  ☐

INCORPORATION BY REFERENCE

On May 4, 2026, InflaRx N.V. (the “Company”) issued a press release titled “InflaRx Reports Favorable Reactive Metabolite Profile for Izicopan in Human Liver Microsomes.”

The Company today announced new preclinical data demonstrating low reactive metabolite formation of izicopan, a next-generation oral C5aR1 inhibitor, in human liver microsomes. In a head-to-head in vitro study, using a standard glutathione (GSH) trapping assay in human liver microsomes (10 μM; 0–40 minute incubation), izicopan demonstrated minimal reactive metabolite formation, with conjugate remaining low throughout the incubation period. These findings support a low level of bioactivation in this assay system.

In this experimental setting, these preclinical findings of izicopan support a low level of bioactivation in the assay system and a lower extent of reactive intermediate formation. Reactive metabolite formation is widely used in drug development as an early mechanistic indicator of potential bioactivation-related safety risk, and these results support izicopan’s differentiated profile within the C5aR inhibitor class.

Under the same experimental conditions, avacopan showed higher levels of thiol adducts, including both glutathione and downstream cysteine conjugates, consistent with more extensive oxidative bioactivation. Differences in total reactive conjugate peak areas were most pronounced at early time points (exceeding 100-fold at 5 and 10 minutes) and remained observable over the course of the assay (approximately 10-fold at 20 and 40 minutes). Overall, these results suggest a lower extent of reactive intermediate formation for izicopan in this experimental setting. While in vitro findings do not directly predict clinical outcomes, InflaRx believes these results support the differentiated profile of izicopan.

This report on Form 6-K (the “Report”) shall be deemed to be incorporated by reference into (i) the registration statements on Form S-8 (File No. 333-221656 and 333-240185) and (ii) the registration statement on Form F-3 (File No. 333-273058) of the Company and to be a part thereof from the date on which this Report is submitted, to the extent not superseded by documents or reports subsequently filed or furnished.

A copy of the press release is attached as Exhibit 99.1 to this Report. Exhibit 99.1 shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act.

FORWARD-LOOKING STATEMENTS

This Report contains forward-looking statements. All statements other than statements of historical fact are forward-looking statements, which are often indicated by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “estimate,” “believe,” “predict,” “potential” or “continue,” among others. Forward-looking statements appear in a number of places throughout this Report and may include statements regarding our intentions, beliefs, projections, outlook, analyses, current expectations and the risks, uncertainties and other factors described under the headings, “Risk factors” and “Cautionary statement regarding forward-looking statements,” in our periodic filings with the U.S. Securities and Exchange Commission. These statements speak only as of the date of this Report and involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Given these risks, uncertainties and other factors, you should not place undue reliance on these forward-looking statements, and we assume no obligation to update these forward-looking statements, even if new information becomes available in the future, except as required by law.

EXHIBIT INDEX

Exhibit No.	Description
99.1	Press Release, dated May 4, 2026

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.

	INFLARX N.V.
Date: May 4, 2026
	By:	/s/ Niels Riedemann
		Name: Niels Riedemann
		Title: Chief Executive Officer

Exhibit 99.1

InflaRx Reports Favorable Reactive Metabolite Profile for Izicopan in Human Liver Microsomes

Jena, Germany, May 4, 2026 – InflaRx N.V. (Nasdaq: IFRX), a biopharmaceutical company pioneering anti-inflammatory therapeutics by targeting the complement system, today announced new preclinical data demonstrating low reactive metabolite formation of izicopan in human liver microsomes. Reactive metabolite formation is widely used in drug development as an early mechanistic indicator of potential bioactivation-related safety risk.

Izicopan is an investigational next-generation oral C5aR1 inhibitor designed to achieve differentiated pharmacological properties, with the potential for improved efficacy and safety. The marketed comparator, avacopan, is a first-in-class oral C5a receptor 1 (C5aR1) inhibitor approved for the treatment of ANCA-associated vasculitis.

In a head-to-head in vitro study using a standard glutathione (GSH) trapping assay in human liver microsomes (10 µM; 0–40 minute incubation), izicopan demonstrated minimal reactive metabolite formation, with conjugate remaining low throughout the incubation period. These findings support a low level of bioactivation in this assay system.

Under the same experimental conditions, avacopan showed higher levels of thiol adducts, including both glutathione and downstream cysteine conjugates, consistent with more extensive oxidative bioactivation. Differences in total reactive conjugate peak areas were most pronounced at early time points (exceeding 100-fold at 5 and 10 minutes) and remained observable over the course of the assay (approximately 10-fold at 20 and 40 minutes). Overall, these results suggest a lower extent of reactive intermediate formation for izicopan in this experimental setting.

While in vitro findings do not directly predict clinical outcomes, InflaRx believes these results support the differentiated profile of izicopan.

Prof. Renfeng Guo, Chief Scientific Officer and Founder of InflaRx, commented: “These data provide additional insight into the mechanistic profile of izicopan. We believe that, if supported by clinical data, such properties may contribute to its overall differentiation within the C5aR inhibitor class."

About izicopan

Izicopan is an orally administered, small molecule inhibitor of the C5a receptor C5aR1 that has shown anti-inflammatory therapeutic effects in several pre-clinical disease models and in human studies. Further, in contrast to the marketed C5aR inhibitor, in vitro experiments demonstrated that izicopan does not inhibit the cytochrome P450 3A4 (CYP3A4) enzyme, which plays an important role in the metabolism of a variety of metabolites and drugs, including glucocorticoids. Reported results from a first-in-human study demonstrated that izicopan was well tolerated in treated subjects and exhibited no safety signals of concern in single doses ranging from 3 mg to 240 mg or multiple doses ranging from 30 mg once per day to 90 mg twice per day for 14 days. Pharmacokinetic / pharmacodynamic data support the best-in-class potential of izicopan, with a ≥90% blockade of C5a-induced neutrophil activation achieved over the 14-day dosing period. Topline Phase 2a data further support the safety profile of izicopan, with no reported safety signals of concern. In patients with hidradenitis suppurativa, over 4 weeks of therapy, izicopan provided rapid and clinically meaningful reductions in abscesses and nodules (ANs) and draining tunnels (dTs), robust HiSCR responses that continued to deepen four weeks after the treatment period, and substantial reductions in patient-reported pain scores, overall demonstrating the potential for biologic-like efficacy. In chronic spontaneous urticaria, InflaRx observed substantial reductions in the 7-day Urticaria Activity Score (UAS7) broadly across patients and particularly in those with severe disease, as well as improved disease control as measured by the Urticaria Control Test (UCT7).

About InflaRx N.V.

InflaRx (Nasdaq: IFRX) is a biopharmaceutical company pioneering anti-inflammatory therapeutics by applying its proprietary anti-C5a and anti-C5aR technologies to discover, develop and commercialize highly potent and specific inhibitors of the complement activation factor C5a and its receptor, C5aR. C5a is a powerful inflammatory mediator involved in the progression of a wide variety of inflammatory diseases. InflaRx‘s lead program is izicopan, an orally administered small molecule inhibitor of C5a-induced signaling via the C5a receptor, which has shown promising PK/PD characteristics as well as therapeutic potential in Phase 1 and Phase 2a clinical studies. The Company is developing izicopan for the treatment of several inflammatory diseases, including hidradenitis suppurativa. InflaRx also has developed vilobelimab, a novel, intravenously delivered, first-in-class, anti-C5a monoclonal antibody that selectively binds to free C5a and has demonstrated disease-modifying clinical activity and tolerability in multiple clinical studies.

InflaRx was founded in 2007, and the group has offices and subsidiaries in Jena and Munich, Germany, as well as Ann Arbor, MI, USA. For further information, please visit www.inflarx.de. InflaRx GmbH (Germany) and InflaRx Pharmaceuticals Inc. (USA) are wholly owned subsidiaries of InflaRx N.V. (together, InflaRx).

Contacts:

InflaRx N.V.	MC Services AG
Jan Medina, CFA	Katja Arnold, Laurie Doyle, Dr. Regina Lutz
Vice President, Head of Investor Relations	Email: inflarx@mc-services.eu
Email: IR@inflarx.de	Europe: +49 89-210 2280
	U.S.: +1-339-832-0752

FORWARD-LOOKING STATEMENTS

This press release contains forward-looking statements. All statements other than statements of historical fact are forward-looking statements, which are often indicated by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “estimate,” “believe,” “predict,” “potential” or “continue,” among others. Forward-looking statements appear in a number of places throughout this release and may include statements regarding our intentions, beliefs, projections, outlook, analyses and current expectations concerning, among other things, the success of our future clinical trials for vilobelimab's treatment of other debilitating or life-threatening inflammatory indications, including acute respiratory distress syndrome, or ARDS; potential strategic transactions or collaborations, including a potential partnership of izicopan, or vilobelimab for PG; the success of our future clinical trials for  izicopan, and whether such clinical results will reflect results seen in previously conducted pre-clinical studies and clinical trials; the timing, progress and results of pre-clinical studies and clinical trials of vilobelimab, izicopan and any other of our product candidates and statements regarding the timing of initiation and completion of studies or trials and related preparatory work, the period during which the results of the trials will become available, the costs of such trials and our research and development programs generally; our interactions with regulators regarding the results of clinical trials and potential regulatory approval pathways, including related to our biologics license application submission for GOHIBIC (vilobelimab), and our ability to obtain and maintain full regulatory approval of vilobelimab or GOHIBIC (vilobelimab) for any indication; whether the FDA, or any comparable foreign regulatory authority will accept or agree with the number, design, size, conduct or implementation of our clinical trials, including any proposed primary or secondary endpoints for such trials; our ability to leverage our proprietary anti-C5a and anti-C5aR technologies to discover and develop therapies to treat complement-mediated immunological and inflammatory diseases; our ability to protect, maintain and enforce our intellectual property protection for vilobelimab, izicopan and any other product candidates, and the scope of such protection; our manufacturing capabilities and strategy, including the scalability and cost of our manufacturing methods and processes and the optimization of our manufacturing methods and processes, and our ability to continue to rely on our existing third-party manufacturers and our ability to engage additional third-party manufacturers for our planned future clinical trials and for commercial supply of vilobelimab and for the finished product GOHIBIC (vilobelimab); our estimates of our expenses, ongoing losses, future revenue, capital requirements and our needs for or ability to obtain additional financing; our ability to defend against liability claims resulting from the testing of our product candidates in the clinic or, if approved, any commercial sales; if any of our product candidates obtain regulatory approval, our ability to comply with and satisfy ongoing obligations and continued regulatory overview; our ability to comply with enacted and future legislation in seeking marketing approval or commercialization; our future growth and ability to compete, which depends on our retaining key personnel and recruiting additional qualified personnel; and our competitive position and the development of and projections relating to our competitors in the development of C5a and C5aR inhibitors or our industry; and the risks, uncertainties and other factors described under the heading “Risk Factors” in our periodic filings with the SEC. These statements speak only as of the date of this press release and involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Given these risks, uncertainties and other factors, you should not place undue reliance on these forward-looking statements, and we assume no obligation to update these forward-looking statements, even if new information becomes available in the future, except as required by law.

FAQ

What did InflaRx (IFRX) report about izicopan in its latest Form 6-K?

InflaRx reported preclinical data showing izicopan had low reactive metabolite formation in human liver microsomes. In a glutathione trapping assay, conjugate levels stayed low over 0–40 minutes, suggesting limited bioactivation in this experimental setting compared with the marketed C5aR1 inhibitor avacopan.

How did izicopan compare with avacopan in human liver microsome testing for InflaRx (IFRX)?

Under identical assay conditions, avacopan showed higher thiol adduct levels than izicopan, including glutathione and cysteine conjugates. Reactive conjugate peak areas for avacopan exceeded those of izicopan by more than 100-fold at 5 and 10 minutes and around 10-fold at 20 and 40 minutes.

What clinical data has InflaRx (IFRX) disclosed for izicopan so far?

InflaRx reports that a first-in-human study found izicopan well tolerated from 3 mg to 240 mg single doses and 30 mg once daily to 90 mg twice daily for 14 days. No safety signals of concern were seen, and pharmacodynamic data showed at least 90% blockade of C5a-induced neutrophil activation.

In which diseases is InflaRx (IFRX) evaluating izicopan?

InflaRx is developing izicopan for several inflammatory diseases, including hidradenitis suppurativa and chronic spontaneous urticaria. Phase 2a data showed reductions in abscesses, nodules, draining tunnels, pain scores, and Urticaria Activity Score and improved Urticaria Control Test results in these indications.

How does InflaRx (IFRX) describe izicopan’s potential safety and efficacy profile?

Izicopan is described as a next-generation oral C5aR1 inhibitor with differentiated pharmacological properties and potential for improved efficacy and safety. It showed no cytochrome P450 3A4 inhibition in vitro and strong C5a-induced neutrophil blockade, and new preclinical data suggest lower reactive metabolite formation than avacopan.

Filing Exhibits & Attachments

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