Boundless Bio, Inc.

This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, statements regarding the structure and intended tax treatment of the proposed Merger; expectations regarding the ownership structure of the combined company; the expected management team of the combined company; expectations regarding the structure, size, timing and completion of the Pre-Closing Financing and Nasdaq listing; the potential Pre-Closing Dividend; expectations regarding the clinical development of BBI-940; and other statements that are not historical fact. These forward-looking statements are made as of the date they were first issued, and were based on the then-current expectations, estimates, forecasts, and projections, as well as the beliefs and assumptions of management. There can be no assurance that future developments affecting Boundless Bio, Serapha or the Contemplated Transactions will be those that have been anticipated.

Forward-looking statements are subject to a number of risks and uncertainties, many of which involve factors or circumstances that are beyond Boundless Bio’s and Serapha’s control. Boundless Bio’s actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including but not limited to (i) the risk that the conditions to the Closing are not satisfied; (ii) uncertainties as to the timing of the consummation of the proposed Merger and the ability of each of Boundless Bio and Serapha to consummate the proposed Merger; (iii) risks related to Boundless Bio’s ability to manage its operating expenses and its expenses associated with the proposed Merger pending Closing; (iv) risks related to the failure or delay in obtaining required approvals from any governmental or regulatory entity necessary to consummate the proposed Merger, if applicable; (v) the risk that as a result of adjustments to the Exchange Ratio, Boundless Bio’s stockholders and Serapha’s stockholders could own more or less of the combined company than is currently anticipated; (vi) risks related to the market price of Boundless Bio Common Stock relative to the value suggested by the Exchange Ratio and the anticipated cash dividend; (vii) unexpected costs, charges or expenses resulting from the proposed Contemplated Transactions; (viii) the risk that anticipated ownership percentages or cash dividend amount may change based on adjustments at or prior to closing; (ix) the risk that the Pre-Closing Financing is not consummated; (x) Serapha’s reliance on intellectual property rights under its license agreement with YolTech Therapeutics and risks related to the protection of intellectual property; and (xi) the potential for the occurrence of any event, change or other circumstance or condition that could give rise to the termination of the Merger Agreement and the other agreements entered into in connection therewith. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties. These and other risks and uncertainties are more fully described in periodic filings with the SEC, including the factors described in the section titled “Risk Factors” in Boundless Bio’s Annual Report on Form 10-K for the year ended December 31, 2025 filed with the SEC, and in other filings that Boundless Bio makes and will make with the SEC in connection with the proposed Merger, including the Proxy Statement (as defined below). You should not place undue reliance on these forward-looking statements, which are made only as of the date hereof or as of the dates indicated in the forward-looking statements. Boundless Bio expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based. This communication does not purport to summarize all of the conditions, risks and other attributes of an investment in Boundless Bio or Serapha.