Onconetix registers 11.5M shares for resale by selling stockholders; company receives no proceeds

The last reported sale price of our Common Stock on The Nasdaq Capital Market on April 24, 2026 was $0.5880 per share.

The offering price of our Common Stock to be sold by the Selling Stockholder does not necessarily bear any relationship to our book value, assets, past operating results, financial condition, or any other established criteria of value.

To the extent that the Company sells shares of Common Stock under the ELOC Purchase Agreement, substantial amounts of shares could be issued and resold, which would cause dilution and may impact the Company's stock price.

As of December 31, 2025, we had cash of approximately $5.2 million, a working capital deficit of approximately $3.1 million and an accumulated deficit of approximately $131.2 million. During the year ended December 31, 2025, we used approximately $9.7 million in cash for operating activities. In addition, as of April 24, 2026, our cash balance was approximately $4.2 million. We believe that our current cash balance is not sufficient to fund its operations for one year from the date of issuance of the consolidated financial statements for the year. While such capital raises may enable us to sustain current operations and meet existing obligations, we continue to generate recurring net operating losses and have not yet established sustained positive cash flows to support our strategic growth initiatives. Such initiatives include the commercialization of Proclarix and our development and commercialization of future product candidates. These factors raise substantial doubt on our ability to continue as a going concern for one year from the date of issuance of our consolidated financial statements for the financial year ended December 31, 2025.

However, in light of (i) the time and resources needed to continue pursuing commercialization of ENTADFI, and (ii) the Company’s cash runway and indebtedness, the Company abandoned commercialization of ENTADFI and no longer holds remaining inventory of the product as of December 31, 2025. In addition, as part of cost reduction efforts and in connection with our initial pause in commercializing ENTADFI, we terminated three employees involved with the ENTADFI program, effective April 30, 2024, with such individuals to continue assisting the Company on an as-needed, consulting basis. Based on the circumstances surrounding ENTADFI, at June 30, 2024, the ENTADFI assets were fully impaired.

Pursuant to the Share Exchange Agreement, subject to the terms and conditions set forth therein, the Seller agreed to contribute and transfer to us, and we agreed to acquire and accept, all of the issued and outstanding equity interests of Realbotix (the “Realbotix Interests”) in exchange for newly issued shares of Common Stock. ... In full consideration for the contribution of the Realbotix Interests, we will issue shares of Common Stock to the Seller (the “Exchange Shares”), such that, immediately following the Closing and after giving effect to such issuance, the Seller will own a percentage of our fully diluted shares (the “Fully Diluted Shares”) that will be adjusted based on Net Cash (as defined below) as follows: (i) if Net Cash is greater than or equal to $12.5 million, but less than $15.0 million, Seller will own 90% of the Fully Diluted Shares, (ii) if Net Cash is greater than or equal to $15.0 million, but less than $18.0 million, Seller will own 85% of the Fully Diluted Shares, (iii) if Net Cash is greater than or equal to $18.0 million, but less than $20.0 million, Seller will own 80% of the Fully Diluted Shares and (iv) if Net Cash is greater than or equal to $20.0 million, Seller will own 75% of the Fully Diluted Shares.

On September 22, 2025, the Company entered into a securities purchase agreement (the "Series D Securities Purchase Agreement") with eleven institutional investors, and sold or exchanged debt, to such investors (collectively, the "Series D PIPE Investors") an aggregate of 16,099 shares of Series D convertible preferred stock, par value $0.00001 per share ("Series D Preferred Stock"), which includes an issuance of 500 shares of Series D Preferred Stock to the lead investor in consideration for the Series D PIPE Investors' irrevocable commitment to purchase shares of the Series D Preferred Stock, and warrants (the "Series D Warrants") to purchase 872,565 shares of Common Stock on a post-reverse split basis, for an aggregate purchase price of approximately $12.9 million and net cash proceeds of $9.3 million. On October 1, 2025, the Company entered into a securities purchase agreement (the "Series E Securities Purchase Agreement") with institutional investor(s) and sold to such institutional investors(s) (collectively, the "Series E PIPE Investors"), an aggregate of 7,813 shares of Series E convertible preferred stock, par value $0.00001 per share ("Series E Preferred Stock"), which are convertible into common stock of the Company, $0.00001 par value per share and warrants (the "Series E Warrants") to purchase 405,045 shares of Common Stock on a post-reverse split basis, for an aggregate purchase price of approximately $6.25 million, which was also equal to the net cash proceeds.

Up to 25,000,000 shares of Common Stock (assuming the shares to be issued are sold at a price of approximately $0.6771 per share, which, in accordance with the terms of the ELOC Purchase Agreement, is equivalent to or greater than 90% of the daily volume weighted average price (the “VWAP”) of the Common Stock for the five trading days immediately preceding April 24, 2026)

We are not selling any securities under this prospectus and will not receive any proceeds from the sale of Common Stock by the Selling Stockholder pursuant to this prospectus.

We may receive up to $25.0 million in aggregate gross proceeds from Keystone under the ELOC Purchase Agreement in connection with sales of the shares of our Common Stock pursuant to the ELOC Purchase Agreement after the date of this prospectus.

Through April 24, 2026, the Company has sold approximately 701,933 split-adjusted shares under the ELOC Purchase Agreement for aggregate proceeds of approximately $8.1 million.

Pursuant to the ELOC Purchase Agreement, 30% of the gross proceeds to the Company from any sale of Common Stock thereunder must be applied towards the redemption of the Company’s Series C Preferred Stock. As of the date of this prospectus, there are seven shares of Series C stock remain to be redeemed.

These factors raise substantial doubt on our ability to continue as a going concern for one year from the date of issuance of our consolidated financial statements for the financial year ended December 31, 2025.

Our net loss was $14.0 million and $58.7 million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $131.2 million.

As of December 31, 2025, we had cash of approximately $5.2 million, a working capital deficit of approximately $3.1 million and an accumulated deficit of approximately $131.2 million. In addition, as of April 24, 2026, our cash balance was approximately $4.2 million.

In particular, the development and commercialization of Proclarix in the United States is being pursued by Labcorp, pursuant to an exclusive license agreement that grants Labcorp the exclusive right to develop and commercialize Proclarix, and other products developed by Labcorp using Proteomedix’s intellectual property covered by the license, in the United States for identification, screening, staging, predisposition, diagnosis, prognosis, monitoring, prevention or treatment selection with respect to prostate cancer. However, we do not have control over Labcorp’s development and commercialization of Proclarix, and there can be no guarantee that Labcorp will continue to advance development and commercialization efforts, or that Labcorp will successfully commercialize Proclarix in the United States.

If all of the 25,000,000 shares of our Common Stock offered for resale by the Selling Stockholders under this prospectus were issued and outstanding as of April 24, 2026, such shares would represent approximately 68.8% of the total number of shares of our Common Stock outstanding.

As a result, investors who purchase Common Stock from Keystone in this offering at different times will likely pay different prices for those shares of Common Stock, and so may experience different levels of dilution and in some cases substantial dilution and different outcomes in their investment results.

There can be no assurance that the Realbotix Transactions will be completed, or if completed, that they will be completed on the same or similar terms to those set out in our previous disclosure. The Realbotix Transactions are subject to the satisfaction of a number of conditions precedent, some of which are outside our control, which include, among others, performance by Simulacra and Realbotix of their respective obligations and covenants in the Share Exchange Agreement.

Pursuant to the ELOC Purchase Agreement, up to 30% of the proceeds from each Fixed Purchase and VWAP Purchase Notice must be used to redeem shares of Series C Preferred Stock.

Keystone Capital Partners, LLC ... 25,000,000 ... KCP Fund I, LLC ... 25,000,000

the Company may not issue shares to the Selling Stockholder under the ELOC Purchase Agreement to the extent that such issuance would cause the Selling Stockholder, together with its affiliates and attribution parties, to beneficially own a number of shares of Common Stock which would exceed 4.99% of our then outstanding Common Stock following such issuance

Based on 11,464,572 shares outstanding as of April 24, 2026.

which contains an explanatory paragraph regarding the Company’s ability to continue as a going concern