Material Agreement (Form 8-K)

Item 1.01. Entry into a Material Definitive Agreement.

PIPE Financing

On October 1, 2025, Onconetix, Inc., a Delaware corporation (the "Company"), entered into, and sold to institutional investor(s) (collectively, the "PIPE Investors"), pursuant to a securities purchase agreement (the "Securities Purchase Agreement") 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 (the "Common Stock") and warrants to purchase 2,025,223 shares of Common Stock (the "Warrants" and, together with the Series E Preferred Stock, the "PIPE Securities"), for an aggregate purchase price of approximately $6.25 million. Such investment is referred to as the "PIPE Financing."

Concurrently with entering into the Securities Purchase Agreement, the Company also entered into a registration rights agreement with the PIPE Investors, pursuant to which it has agreed to provide the PIPE Investors with certain registration rights related to the shares of Common Stock underlying the shares of Series E Preferred Stock (the "Preferred Shares") and Warrants, as described below. The following description of the terms of the Securities Purchase Agreement and the Certificate of Designations of Preferences, Rights and Limitations of the Series E Preferred Stock (the "Certificate of Designations"), Warrants and Registration Rights Agreement are only summaries and do not purport to be complete and are qualified in their entirety by reference to the full text of each of those transaction documents, copies of which are filed as Exhibits 10.1, 3.1, 4.1 and 10.2, respectively, to this Current Report on Form 8-K, and are incorporated by reference herein. Capitalized terms used but not defined herein will have the meanings assigned to them in the Securities Purchase Agreement, Certificate of Designations, Warrants or Registration Rights Agreement, as the case may be.

Series E Preferred Stock

Certificate of Designations

General. Pursuant to the Certificate of Designations, the Company has authorized the issuance of up to 10,000 shares of Series E Preferred Stock, each having a stated value of $1,000 per share (the "Stated Value").

Ranking. Except (i) for the Series C Preferred Stock of the Company and the Series D Preferred Stock of the Company, which shall be of pari passu rank to the Preferred Shares (the "Parity Stock"), and (ii) to the extent that the Required Holders (as defined in the Securities Purchase Agreement) expressly consent to the creation of Parity Stock or Senior Preferred Stock, all shares of capital stock of the Company will be junior in rank to all Preferred Shares with respect to the preferences as to dividends, distributions and payments upon the liquidation, dissolution and winding up of the Company.

Dividends. The holders of Series E Preferred Stock are entitled to dividends (the "Dividends"), when and as declared by the Company's Board of Directors (the "Board"), from time to time, in its sole discretion, which Dividends shall be paid by the Company out of funds legally available therefor, payable, subject to the conditions and other terms hereof, in cash, in securities of the Company or any other entity, or using assets as determined by the Board on the Stated Value of such Preferred Share. In addition, from and after the occurrence and during the continuance of any Triggering Event, dividends ("Default Dividends") will accrue on the Stated Value of each Preferred Share at a rate of fifteen percent (15.0%) (the "Default Rate") per annum. Default Dividends are payable by way of inclusion of Default Dividends in the Conversion Amount (as defined below) on each conversion date. In the event that such Triggering Event is subsequently cured (and no other Triggering Event then exists), the accrual of Default Dividends will cease to be effective as of the calendar day immediately following the date of such cure; provided that Default Dividends as calculated and unpaid during the continuance of such Triggering Event will continue to apply to the extent relating to the days after the occurrence of such Triggering Event through and including the date of such cure of such Triggering Event.