Veraxa Biotech reports tumor regression in animal model

In a xenograft breast cancer model, a single 3 mg/kg dose produced strong tumor regression, with no observed decrease in body weight in the treatment arm.

Rhea-AI Filing Summary

VRXA (Veraxa Biotech AG) presented first in vivo proof-of-concept and additional in vitro data for its BiTAC-ADC technology at the 17th World ADC Congress. The company reported strong tumor regression in a xenograft breast cancer model after a single systemic dose of 3 mg/kg, with no observed decrease in body weight in the treatment arm.

The release says a construct with one non-targeted component showed no significant effect; a control ADC using the same conjugation and linker-payload technology and drug-antibody ratio performed similarly. Additional in vitro results reported discrimination between cancer and healthy cells, a requirement for both constructs to be co-targeted to the tumor site, and no release of active toxins in the periphery. The company cautions that preclinical results may not predict later-stage trials or results in humans.

Key Figures

Dose: 3 mg/kg BiTAC-ADC components: 2 components Non-targeted component: 1 component +1 more

4 metrics

Dose 3 mg/kg Single systemic dose in the xenograft breast cancer model.

BiTAC-ADC components 2 components Described as a two-component technology.

Non-targeted component 1 component The construct using one non-targeted component showed no significant effect.

Congress edition 17th World ADC Congress The company presented the data at this congress.

Key Terms

BiTAC-ADC, drug-antibody ratio (DAR), xenograft, prodrug, +1 more

5 terms

BiTAC-ADC technical

"novel BiTAC-ADC technology platform"

An antibody-drug conjugate (ADC) with the investigational name BITAC-ADC is a targeted cancer therapy that combines a cancer-seeking antibody with a potent drug, so the treatment behaves like a guided missile that delivers chemotherapy directly to tumor cells while sparing healthy tissue. Investors watch ADC candidates closely because their clinical trial results, safety profile and regulatory approvals can drastically affect a developer’s future revenue and stock value, but they also carry high clinical and regulatory risk.

drug-antibody ratio (DAR) medical

"same drug-antibody ratio (DAR) as its BiTAC-ADC counterpart"

Drug-antibody ratio (DAR) is the average number of cytotoxic drug molecules chemically attached to each antibody molecule in an antibody-drug conjugate (ADC). It is calculated by measuring the distribution of conjugated species (antibodies carrying 0, 1, 2, … drug units) and reporting the mean number of drug payloads per antibody; DAR is a key manufacturing and quality attribute because the average value and the spread of that distribution influence an ADC’s potency, stability, solubility, and how it behaves in the body. DAR is an average across all molecules in a batch rather than a count on any single antibody, and analytic methods such as mass spectrometry or chromatographic techniques are used to determine it.

xenograft medical

"xenograft breast cancer model"

A xenograft is biological tissue or cells taken from one species and placed into another, most commonly human tumor cells implanted into laboratory animals to study disease or test drugs. Investors watch xenograft results because they serve like a controlled dress rehearsal for a therapy: positive responses in these models can de‑risk programs, attract funding or partnerships, and influence the likelihood and timing of clinical trials and regulatory milestones.

prodrug medical

"systemically inactive prodrug"

A prodrug is an inactive or less-active compound that is designed to be converted into an active drug inside the body, like a packaged meal that needs heating before it's ready to eat. For investors, prodrugs matter because this design can improve how a medicine is absorbed, reduce side effects, extend patent protection, or enable new dosing forms — all factors that can affect a drug's regulatory path, marketability, and commercial value.

proactivator medical

"cell-impermeable proactivator"

FAQ

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

What did VERAXA (VRXA) report from its BiTAC-ADC breast cancer model?

VERAXA reported strong tumor regression after a single 3 mg/kg dose in a xenograft breast cancer model. It also reported no observed decrease in body weight in the BiTAC-ADC treatment arm.

Did the single-component BiTAC-ADC show an effect?

The BiTAC-ADC using one non-targeted component, which delivered only one component to the tumor, showed no significant effect. A control ADC using the same conjugation and linker-payload technology and the same drug-antibody ratio performed similarly.

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

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 10/15/2026 - 04:10 PM EDT Accepted by SEC EDGAR 10/15/2026 - 04:10 PM EDT Learn about SEC filing dates

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 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 October 2026

Commission File Number: 001-43342

Veraxa Biotech AG

Talacker 35

8001 Zurich, Switzerland

(Address of principal executive office)

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 ☐

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): ☐

Presentation of in vivo Proof-of-Concept Data for BiTAC^®-ADC Technology

On October 13, 2026, the Veraxa Biotech AG (the “Company”) issued a press release announcing the presentation of in vivo proof-of-concept data and additional in vitro data validating its novel BiTAC-ADC technology platform.

A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

EXHIBIT INDEX

Exhibit		Description of Exhibit
99.1		Press Release dated October 13, 2026

1

SIGNATURE

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

	VERAXA BIOTECH AG
Date: October 15, 2026	By:	/s/ Christoph Antz
	Name:	Christoph Antz
	Title:	Chief Executive Officer

	By:	/s/ Oliver Baumann
	Name:	Oliver Baumann
	Title:	Chairman of the Board of Directors

2

Exhibit 99.1

Press Release

VERAXA Biotech Presents in vivo Proof-of-Concept Data for
BiTAC^®-ADC Technology at World ADC Congress

In vivo data confirm activation of prodrug payload inside tumor cells following systemic administration
of BiTAC-ADC molecules leading to potent anti-tumor activity

ZURICH, SWITZERLAND – October 13, 2026 – VERAXA Biotech AG (NASDAQ: VRXA; “VERAXA”), an emerging leader in designing novel cancer therapies, today presented first in vivo proof-of-concept data and additional in vitro data validating its novel BiTAC-ADC technology platform at the 17^th World ADC Congress in San Diego, CA, USA. The in vivo data demonstrate that a systemically applied, single dose of the two-component BiTAC-ADC selectively triggered a tumor-specific response resulting in a significant reduction in tumor volume, while continuing to show differentiated safety features and the potential to overcome systemic toxicity, the primary limitation of current ADCs.

The in vivo data presented at the World ADC Congress showed that treatment with BiTAC-ADCs resulted in strong tumor regression in a xenograft breast cancer model even at a single dose of 3 mg/kg. As intended, BiTAC-ADCs utilizing one non-targeted component, thereby only delivering one component to the tumor, showed no significant effect. A control ADC, engineered by VERAXA using the same conjugation and linker-payload technology and with the same drug-antibody ratio (DAR) as its BiTAC-ADC counterpart, performed similarly. In the BiTAC-ADC treatment arm, no decrease in body weight could be observed.

“These novel datasets on the BiTAC-ADC platform underline the rapid progress our team has made in demonstrating the potentially transformative safety benefits of BiTAC-ADCs compared to conventional ADCs,” said Christoph Erkel, Ph.D., Chief Scientific Officer at VERAXA. “While BiTAC-TCEs remain our priority, the rapid validation of our BiTAC-ADC concept bodes well for establishing a second pillar in our R&D and partnering strategy towards safer drugs for solid tumor patients.”

“Demonstrating that BiTAC-ADCs can reach the tumor site following intravenous administration, induce a specific effect only upon arrival of both BiTAC components, and shrink the tumor in a living organism is a significant platform milestone and validates its underlying concept,” added Paul Sauter, Ph.D., Senior Director and Department Head ADC Tech & Chemistry at VERAXA.

The poster presented at the World ADC congress also expanded on previously published in vitro studies and shows that BiTAC-ADCs can discriminate between cancer and healthy cells, require both BiTAC-ADC constructs to be co-targeted to the tumor site and do not release active toxins in the periphery. The BiTAC-ADC concept was also successfully evaluated across a wide range of cancer cell lines and against several validated ADC targets. Taken together, the data sets underline the potential for this novel therapeutic concept with comparable efficacy to a conventional ADC, but a mechanistically highly differentiated safety profile.

VERAXA Biotech AG / Talacker 35 / CH-8001 Zürich

VERAXA Biotech GmbH / Im Neuenheimer Feld 584 / 69120 Heidelberg

The BiTAC therapeutic strategy is designed to unlock a new level of precision in cancer treatment via dual-targeting using two complementary precursors and enabling a tumor-restricted activation of the desired therapeutic effect. Applied to the development of antibody drug conjugates (ADCs), the technology delivers a systemically inactive prodrug and a cell-impermeable proactivator through two separate antibodies, each addressing a defined tumor-associated antigen. While the single BiTAC-ADC precursors are therefore not toxic by design, the selective internalization of both components into the same cancer cell leads to dose-dependent cytotoxicity.

The data poster presented will be made available on the Company’s website.

About VERAXA Biotech AG (NASDAQ: VRXA)

At VERAXA, we are building a premier engine for the discovery and development of next-generation antibody-based therapeutics, including bispecific T cell engagers, bispecific ADCs and other innovative formats. Powered by a suite of transformative technologies and guided by rigorous quality-by-design principles, we are rapidly advancing our pipeline of ADCs and proprietary BiTAC formats into clinical development and beyond. VERAXA was founded on scientific breakthroughs made at the European Molecular Biology Laboratory (EMBL), a world-renowned institution known for pioneering life science research and cutting-edge technology.

For regular updates about VERAXA Biotech, visit https://investors.veraxa.com/ or follow us on LinkedIn, X (formerly known as Twitter) and Bluesky.

BiTAC^® is a registered trademark of VERAXA Biotech GmbH.

Forward-looking Statements

This press release may contain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. All statements that address activities, events, or developments that VERAXA Biotech AG (the “Company”) intends, expects, plans, projects, believes, or anticipates will or may occur in the future are forward-looking statements, including the Company’s ability to successfully translate the results obtained in preclinical research into clinical development and marketed therapeutic products. Such forward-looking statements are based on current expectations and involve inherent risks and uncertainties, including factors that could delay, divert or change any of them, and could cause actual outcomes and results to differ materially from current expectations, including the Company’s need for substantial additional funding, which may not be available on acceptable terms or at all; the uncertainties inherent in drug development, including the risk that results of preclinical studies or early-stage clinical trials may not be predictive of results in later-stage trials or in humans, and that interim, topline or preliminary data may change as more patient data become available; the risk that regulatory authorities, including the U.S. Food and Drug Administration, the European Medicines Agency and other comparable authorities, may disagree with the Company’s trial designs, interpretations of data or regulatory strategies, or may not approve its product candidates; the Company’s ability to enter into and maintain collaboration,

VERAXA Biotech AG / Talacker 35 / CH-8001 Zürich

VERAXA Biotech GmbH / Im Neuenheimer Feld 584 / 69120 Heidelberg

2

license or partnering arrangements on favorable terms; competition from other oncology therapies; and the Company’s ability to obtain, maintain, defend and enforce intellectual property protection for its product candidates and technologies. No forward-looking statement can be guaranteed.

Forward-looking statements contained in this press release should be evaluated together with the many uncertainties that affect the Company’s business, particularly those identified or referenced herein and in the risk factors section of the Company’s most recent Annual Report on Form 20-F and any subsequent reports on Form 6-K. These documents are available from the Securities and Exchange Commission, the Company website or from Company Investor Relations.

In addition, any information contained in this press release was current as of the date presented and should not be relied upon as representing our estimates as of any subsequent date. While we may elect to update forward-looking statements at some point in the future, we specifically disclaim any obligation to do so, even if our estimates change, whether as a result of new information, future events or otherwise. Consequently, the company will not update the information contained in this press release, and investors should not rely upon the information as current or accurate after the presentation date.

Contact

VERAXA Biotech AG – Corporate
Christoph Antz, Ph.D.
Chief Executive Officer, Co-Founder
investors@veraxa.com

For Media and Investors – U.S.
Brandon Weiner
ICR Healthcare
VERAXA@icrhealthcare.com

For Media and Investors – EU
Mario Brkulj
media@veraxa.com

VERAXA Biotech AG / Talacker 35 / CH-8001 Zürich

VERAXA Biotech GmbH / Im Neuenheimer Feld 584 / 69120 Heidelberg

3

Filing Exhibits & Attachments

3 documents

Press Releases

• EX-99.1 EXHIBIT 99.1 20.4 KB
• EX-99 GRAPHIC 79.6 KB
• EX-99 GRAPHIC 13.9 KB