If fully exercised, the TO2 warrants will provide CHOSA Oncology with approximately SEK 6.2 million before transaction costs. The proceeds are intended to further accelerate:

      CLIA laboratory certification will enable the transition from Research Use Only (RUO) status to clinical commercialization for patient testing

      The collaboration with Mount Sinai Hospital, New York to prospective validation of the Platin-DRP® in the immune oncology setting (ie products like Keytruda®, and Opdivo®)

      The commercialization and partnering activities in the US

"The exercise period for TO2 represents an opportunity for our shareholders to participate in the next phase of CHOSA's development. The proceeds will support our efforts to advance Platin-DRP® and execute on the milestones we have outlined for 2026," says Peter Buhl Jensen, CEO of Chosa Oncology

Overview:

One (1) warrant of series TO2 entitles the holder to subscribe for one (1) new share in the Company at a price of SEK 0.78. The subscription period for warrants of series TO2 runs from today, 1 July 2026, up to and including 14 July 2026.

Complete terms and conditions for the warrants are available on the Company's website, www.chosaoncology.com.

Please note that warrants not exercised by 14 July 2026, or sold by 10 July 2026, will expire worthlessly. To prevent your TO2 warrants from expiring, you must actively subscribe for shares or sell your warrants. Note that some nominees may close their applications earlier than 14 July 2026.

How to exercise the warrants

Nominee-registered warrants (custody account / ISK / endowment insurance)

Subscription and payment using warrants shall be made in accordance with the instructions from the respective nominee. Please contact your nominees well in advance of 14 July 2026 for further information, as different nominees may have different processing times.

Directly registered warrants (VP account)

Subscription shall be made by submitting an application form together with simultaneous cash payment to the issuing agent Nordic Issuing AB, such that the application form reaches Nordic Issuing no later than 14 July 2026. The application form with payment instructions is available on the Company's website www.chosaoncology.com and on Nordic Issuing AB's website www.nordic-issuing.se.

Advisers

Västra Hamnen Corporate Finance AB is acting as financial adviser and Setterwalls Advokatbyrå as legal adviser in connection with the exercise of TO2. Nordic Issuing AB is acting as issuing agent.

For further information, please contact:

Peter Buhl Jensen, CEO

peter@chosa.bio

+45 21 60 89 22

The information was submitted, through the care of the contact person above, for publication on 1 July 2026 at 08:30 CET.

About Chosa Oncology AB (publ)

CHOSA Oncology is a precision oncology company developing Platin-DRP®, a gene expression-based biomarker that predicts response to platinum-based chemotherapy. By identifying patients most likely to benefit from treatment, CHOSA aims to improve treatment outcomes and optimise treatment choices in cancer care.

Important information

This press release does not constitute a prospectus within the meaning of Regulation (EU) 2017/1129 (the Prospectus Regulation) and has not been approved by any regulatory authority in any jurisdiction. No prospectus has been prepared in connection with the rights issue of units consisting of shares and warrants of series TO 2. The Company has prepared an information document in the form provided for in Annex IX of the Prospectus Regulation (the "Information Document"). The Information Document is available on the Company's website, www.chosaoncology.com. The Swedish Financial Supervisory Authority, which is the national competent authority, has not approved nor reviewed the Information Document. Each investor is advised to make their own assessment of whether it is appropriate to invest in the Company.

This press release does not constitute an offer to, or solicitation of, acquire or subscribe for any securities in the Company in any jurisdiction, either from the Company or any other party. The information in this press release may not be released, published, copied, reproduced or distributed, directly or indirectly, in whole or in part, in or to Australia, Hong Kong, Japan, Canada, New Zealand, Switzerland, Singapore, South Africa, the United States or any other jurisdiction where such release, publication or distribution of this information would be contrary to applicable rules or where such action is subject to legal restrictions. Actions in breach of these instructions may constitute a violation of applicable securities legislation.

Forward-looking statements

This press release contains forward-looking statements regarding the Company's intentions, assessments or expectations concerning the Company's future results, financial position, liquidity, development, outlook, expected growth, strategies and opportunities, as well as the markets in which the Company operates. Forward-looking statements are statements that do not refer to historical facts and can be identified by the fact that they contain expressions such as "believes", "expects", "anticipates", "intends", "estimates", "will", "may", "assumes", "should", "could", and, in each case, their negations, or similar expressions. The Company does not guarantee that the assumptions underlying the forward-looking statements in this press release are correct, and neither the Company nor any other party undertakes to update, confirm or publicly announce any revision of any forward-looking statement, unless required by law or the rules of Spotlight Stock Market.