Business/Financial Results (Form 8-K)

As of June 30, 2026, SELLAS Life Sciences Group, Inc. (the "Company") estimates that its unaudited cash and cash equivalents position was $138.3 million. This amount is unaudited and preliminary and is subject to the completion of financial closing procedures, including management's reviews. As a result, this amount may differ materially from the amount that will be reflected in the Company's financial statements as of and for the six months ended June 30, 2026.

As previously disclosed, the Company commenced a binding arbitration against 3D Medicines, Inc. ("3D Medicines"), administered by the Hong Kong International Arbitration Centre ("HKIAC"). On July 24, 2026, the sole arbitrator in the arbitration proceeding rendered a decision dismissing the Company's claims. As permitted by HKIAC rules, the arbitrator administratively allocated a portion of 3D Medicines' legal fees and costs in the amount of approximately $1.0 million to be paid by the Company.

3D Medicines announced that it will continue to progress the development and commercialization of galinpepimut-S ("GPS") in the Greater China territory in accordance with the terms of the exclusive license agreement, pursuant to which $191.5 million in potential future milestone payments remain as of March 31, 2026, including the $13.0 million milestone payments that were in dispute in the arbitration.