Moleculin cuts warrant price to $0.51, needs cash

The September ATM issuances were followed by a reduction in the Series I Warrants’ exercise price to $0.51 per share.

Rhea-AI Filing Summary

Moleculin Biotech, Inc. (MBRX) announced that the Mexican Patent Office granted Patent No. 436849 for its lung-targeted liposomal Annamycin technology; the patent remains in force until November 23, 2040.

To date in September 2026, Moleculin issued 888,400 common shares through its at-the-market offering for $0.48 million in aggregate gross proceeds. Following completion of those issuances, the company will have 20,385,780 shares outstanding. The Series I Warrants’ exercise price was reduced from $0.75 to $0.51 per share after the ATM share issuances; the warrants cover up to 37,130,001 shares. Moleculin said it will require significant additional financing, for which it has no commitments, to conduct the clinical trials described.

Filing Explained

The filing specifies that Series I warrants have an anti-dilution term: below-price common-stock or equivalent issuances, except certain exempt issuances, can lower their exercise price, subject to a floor; following the ATM issuances, the price was reduced to $0.51.

8-K Event Classification

3 items: 7.01, 8.01, 9.01

3 items

Item 7.01 Regulation FD Disclosure Disclosure

Material non-public information disclosed under Regulation Fair Disclosure, often investor presentations or guidance.

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

Key Figures

Patent term: Until November 23, 2040 ATM shares issued: 888,400 shares Aggregate gross proceeds: $0.48 million +4 more

7 metrics

Patent term Until November 23, 2040 Mexican Patent No. 436849

ATM shares issued 888,400 shares To date in September 2026

Aggregate gross proceeds $0.48 million From the ATM share issuances to date in September 2026

Common shares outstanding 20,385,780 shares Following completion of the described ATM issuances

Series I Warrants Up to 37,130,001 shares Warrants issued August 3, 2026

Initial warrant exercise price $0.75 per share Series I Warrants

Reduced warrant exercise price $0.51 per share After issuance of the ATM shares

Key Terms

At Market Offering Agreement, anti-dilution provisions, liposomal formulation, double-blind, placebo-controlled, +1 more

5 terms

At Market Offering Agreement financial

"entered into an At Market Offering Agreement"

anti-dilution provisions financial

"contain anti-dilution provisions that reduce the exercise price"

Anti-dilution provisions are contract terms that protect an investor’s percentage ownership when a company issues new shares at a lower price than the investor originally paid. They work like an automatic recalculation of split pieces when a pie gets cut into more slices, preserving the investor’s relative stake and reducing unexpected losses of ownership and voting power, which matters because it affects potential control, future returns, and valuation of an investment.

liposomal formulation technical

"The patented liposomal formulation is designed to enhance delivery"

A liposomal formulation is a drug or diagnostic packaged inside tiny spherical fat-based bubbles called liposomes, which carry and protect the active ingredient as it moves through the body. Like a coated delivery truck, liposomes can change how a medicine is absorbed, how long it lasts, and which tissues it reaches, which matters to investors because those effects can influence a product’s safety, effectiveness, regulatory review, and commercial value.

double-blind, placebo-controlled medical

"randomized, double-blind, placebo-controlled Phase 2/3 trial"

A clinical trial design in which participants are randomly assigned to receive either the experimental treatment or an inactive substitute (a placebo), and neither the participants nor the researchers know who is receiving which. This setup limits bias and makes it far easier to tell whether a drug or intervention truly works, similar to a blind taste test, so results carry more weight for regulatory decisions and for investors assessing a product’s commercial prospects.

anthracycline medical

"Annamycin, the Company's next-generation anthracycline"

An anthracycline is a type of powerful medicine used to treat cancer, working by killing or stopping the growth of cancer cells. Because these drugs can have significant side effects and influence healthcare costs, they are closely watched by investors, especially in the pharmaceutical and healthcare sectors. Their development and use can impact the financial performance of companies involved in cancer treatment.

FAQ

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

What patent did Moleculin Biotech (MBRX) receive in Mexico?

The Mexican Patent Office granted Patent No. 436849 for Moleculin’s lung-targeted liposomal Annamycin technology. The patent remains in force until November 23, 2040.

How many MBRX shares were issued through the ATM offering in September 2026?

To date in September 2026, Moleculin issued 888,400 common shares through the at-the-market offering for $0.48 million in aggregate gross proceeds.

How many MBRX shares will be outstanding after the ATM issuances?

Following completion of the described issuances, Moleculin will have 20,385,780 common shares outstanding.

What is the MBRX Series I Warrants’ exercise price after the ATM share issuances?

The exercise price was reduced from $0.75 to $0.51 per share after the ATM share issuances. The warrants were issued on August 3, 2026, and are exercisable for up to 37,130,001 common shares.

What does Moleculin say about financing for its clinical trials?

Moleculin said it will require significant additional financing to conduct the clinical trials described and that it has no commitments for that financing.

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

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Available on EDGAR 09/23/2026 - 08:25 AM Accepted by SEC EDGAR 09/23/2026 - 08:25 AM Learn about SEC filing dates

false 0001659617 0001659617 2026-09-23 2026-09-23

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934

DATE OF REPORT (DATE OF EARLIEST EVENT REPORTED): September 23, 2026

MOLECULIN BIOTECH, INC.

(Exact Name of Registrant as Specified in its Charter)

Delaware	001-37758	47-4671997
(State or Other Jurisdiction of Incorporation or Organization)	(Commission File No.)	(I.R.S. Employer Identification No.)

5300 Memorial Drive, Suite 950, Houston, TX 77007

(Address of principal executive offices and zip code)

(713) 300-5160

(Registrant’s telephone number, including area code)

(Former name or former address, if changed from last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-14(c))

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).          Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol (s)	Name of each exchange on which registered
Common Stock, par value $.001 per share	MBRX	The NASDAQ Stock Market LLC

Item 7.01 Regulation FD Disclosure

On September 23, 2026, Moleculin Biotech, Inc. (the “Company”), issued a press release which announced that the Mexican Patent Office has granted Patent No. 436849, further strengthening the Company's global intellectual property portfolio protecting its proprietary lung-targeted liposomal Annamycin technology.

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

The information contained in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1, is being furnished and shall not be “filed” for the purpose of the Securities Exchange Act of 1934, as amended (“Exchange Act”), nor shall it be incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended (“Securities Act”), unless specifically identified therein as being incorporated by reference.
 

Item 8.01 Other Events

As previously reported, in July 2025 the Company entered into an At Market Offering Agreement (the "Agreement") with Roth Capital Partners, LLC (the "Roth"). Pursuant to the terms of the Agreement, the Company may offer and sell, from time to time, Company common stock through Roth, acting as agent, through an "at the market offering" as defined in Rule 415(a)(4) (the "ATM Offering") promulgated under the Securities Act. To date in September 2026, the Company issued 888,400 shares of common stock through the ATM Offering for aggregate gross proceeds of $0.48 million. After the completion of the foregoing issuances, the Company will have 20,385,780 shares of common stock outstanding.
 

On August 3, 2026, the Company issued Series I Warrants to purchase up to 37,130,001 shares of common stock in a public offering. The Series I Warrants were initially exercisable into one share of common stock at an exercise price of $0.75 per share and expire on the five-year anniversary of the closing date. The Series I Warrants contain anti-dilution provisions that reduce the exercise price (subject to a floor price) in the event the Company issues common stock or common stock equivalents at a price below the then-current exercise price, other than in connection with certain exempt issuances. Subsequent to the issuance of the shares of common stock in the ATM Offering described above, the exercise price of the Series I Warrants was reduced to $0.51 per share.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.	Description
99.1	Press Release dated September 23, 2026
104	Cover page Interactive Data File (formatted as Inline XBRL document)

SIGNATURE

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

	MOLECULIN BIOTECH, INC.
	Date:	September 23, 2026
	By:	/s/ Jonathan P. Foster
		Jonathan P. Foster

Exhibit 99.1

Moleculin Biotech Secures Mexican Patent Protecting Lung-Targeted Liposomal Annamycin Through 2040

Strengthens Global Intellectual Property Estate for Annamycin's Proprietary Liposomal Formulation Designed to Target Lung Metastases While Supporting Long-Term Commercial Opportunity

HOUSTON, September 23, 2026 /PRNewswire/ -- Moleculin Biotech, Inc., (Nasdaq: MBRX) (“Moleculin” or the “Company”), today announced that the Mexican Patent Office has granted Patent No. 436849, further strengthening the Company's global intellectual property portfolio protecting its proprietary lung-targeted liposomal Annamycin technology.

The newly issued patent supports Moleculin's strategy of building a robust worldwide intellectual property estate around Annamycin, the Company's next-generation anthracycline currently being evaluated in the pivotal MIRACLE trial for relapsed or refractory acute myeloid leukemia (AML), while also reinforcing the platform's broader potential across additional oncology indications.

Unlike conventional anthracyclines, Annamycin was specifically engineered to avoid multidrug resistance mechanisms while demonstrating the ability to penetrate tissues that are traditionally difficult to treat, including the lungs. The patented liposomal formulation is designed to enhance delivery of Annamycin to pulmonary tumors and metastatic disease, potentially expanding future development opportunities beyond hematologic malignancies.

"This newly granted Mexican patent represents another important milestone in strengthening the global intellectual property foundation supporting our Annamycin platform," said Walter Klemp, Chairman and Chief Executive Officer of Moleculin Biotech. "As we continue advancing the MIRACLE trial toward important clinical milestones, we are simultaneously protecting the long-term value of Annamycin through an expanding international patent portfolio. Strong intellectual property is a critical component of building lasting shareholder value, and this patent further reinforces the commercial potential of our proprietary technology platform well into the next decade."

The Mexican patent complements Moleculin's growing international patent estate protecting Annamycin and its proprietary formulations across multiple jurisdictions. The patent remains in force until November 23, 2040, providing long-term exclusivity for the covered technology.

The announcement comes as Moleculin continues to execute on multiple value-driving initiatives centered on Annamycin. The Company's pivotal MIRACLE trial is evaluating Annamycin in combination with high-dose cytarabine for patients with relapsed or refractory AML, an area of significant unmet medical need. In parallel, Moleculin continues to broaden the scientific and commercial foundation supporting future opportunities for the Annamycin platform through ongoing innovation and strategic intellectual property expansion.

As Moleculin advances toward additional clinical milestones, management believes its combination of differentiated science, advancing late-stage development, and expanding global patent protection positions the Company to create meaningful long-term value for patients and shareholders alike.

About Moleculin Biotech, Inc.

Moleculin Biotech, Inc. is a Phase 3 clinical stage pharmaceutical company advancing a pipeline of therapeutic candidates addressing hard-to-treat tumors and viruses. The Company’s lead program, Annamycin (also known as naxtarubicin), is a highly efficacious and well tolerated anthracycline designed to avoid multidrug resistance mechanisms and to lack the cardiotoxicity common with currently prescribed anthracyclines. Annamycin is currently in development for the treatment of relapsed or refractory acute myeloid leukemia (AML) and soft tissue sarcoma (STS) lung metastases.

The Company has begun the MIRACLE (Moleculin R/R AML AnnAraC Clinical Evaluation) Trial (MB-108), a pivotal, adaptive design, multi-center, randomized, double-blind, placebo-controlled Phase 2/3 trial evaluating Annamycin in combination with cytarabine, together referred to as AnnAraC (the combination of Annamycin and cytarabine, also referred to as “Ara-C”) for the treatment of relapsed or refractory acute myeloid leukemia. Following a successful Phase 1B/2 study (MB-106), with input from the FDA, the Company believes it has substantially de-risked the development pathway towards a potential approval for Annamycin for the treatment of AML. This study remains subject to appropriate future filings with potential additional feedback from the FDA and their foreign equivalents.

Additionally, the Company is developing WP1066, an Immune/Transcription Modulator capable of inhibiting p-STAT3 and other oncogenic transcription factors while also stimulating a natural immune response, targeting brain tumors, pancreatic and other cancers. Moleculin also has in its pipeline a portfolio of antimetabolites, including WP1122 for the potential treatment of pathogenic viruses, as well as certain cancer indications.

For more information about the Company, please visit www.moleculin.com and connect on X, LinkedIn and Facebook.

Forward-Looking Statements

Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties. Forward-looking statements in this press release include, without limitation, statements regarding the strength and enforceability of the Company’s intellectual property portfolio, the scope of patent protection and long-term exclusivity provided by issued patents, the commercial potential of the Company’s proprietary technology, and the potential efficacy and safety of Annamycin and AnnAraC in R/R AML . Moleculin will require significant additional financing, for which the Company has no commitments, in order to conduct its clinical trials as described in this press release, and the milestones described in this press release assume the Company’s ability to secure such financing on a timely basis. Although Moleculin believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward-looking statements. The Company relies on the reports of its expert with regard to the absence of cardiotoxicity. The dataset referenced in this press release is subject to the review of the data from future subjects in its current and future clinical trials and long-term follow-up with subjects in its current trials. Moleculin has attempted to identify forward-looking statements by terminology including ‘believes,’ ‘estimates,’ ‘anticipates,’ ‘expects,’ ‘plans,’ ‘projects,’ ‘intends,’ ‘potential,’ ‘may,’ ‘could,’ ‘might,’ ‘will,’ ‘should,’ ‘approximately’ or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including those discussed under Item 1A. “Risk Factors” in our most recently filed Form 10-K filed with the Securities and Exchange Commission (SEC) and updated from time to time in our Form 10-Q filings and in our other public filings with the SEC. Any forward-looking statements contained in this release speak only as of its date. We undertake no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events.

Investor Contact:
JTC Team, LLC

Jenene Thomas

(908) 824-0775

MBRX@jtcir.com

Filing Exhibits & Attachments

5 documents

Press Releases

• EX-99.1 EXHIBIT 99.1 13.1 KB

Other Documents

• EX-101 XBRL TAXONOMY EXTENSION SCHEMA 3.5 KB
• EX-101 XBRL TAXONOMY EXTENSION DEFINITION LINKBASE 11.2 KB
• EX-101 XBRL TAXONOMY EXTENSION LABEL LINKBASE 15.0 KB
• EX-101 XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE 11.3 KB