demonstrated that an enzyme - dead form of PLA2G2D retains potent immunosuppressive activity, establishing that the molecule's role in tumor immune evasion is independent of its enzymatic activity. Apeximmune's anti - PLA2G2D antibody blocks both enzymatic and non - enzymatic functions. • A shot at the patients PD - 1 drugs miss. Anti - PD - 1 therapies have transformed the treatment of certain cancers, but the majority of patients across indications either fail to respond or eventually relapse. Response rates fall to single digits in gastrointestinal cancers and other tumor types . Blockade of PLA2G2D not only restores anti - tumor immunity in preclinical models resistant to anti - PD - 1 therapy but also potentiates the activity of anti - PD - 1 in tumor types that are otherwise unresponsive to checkpoint inhibition. • Where the drug stands. AI - 306 is in IND - enabling development. Cell line development is currently underway, GLP toxicology studies are scheduled to initiate in late 2026, and an IND filing is targeted for Q2 2027. All data are preclinical. No patients have been dosed. • Forward - Looking Statements: This press release contains forward - looking statements, including statements regarding the development of AI - 306, anticipated regulatory milestones including the timing of the IND filing, and the potential clinical and commercial opportunity for PLA2G2D - d irected therapy. Actual results may differ materially from those expressed or implied by these statements as a result of various factors, including the risks inherent in preclinical and clinical drug development. Apeximmune undertakes no obligation to update these statements. K ey T erms • PLA2G2D. Phospholipase A2 group IID. A secreted enzyme made mainly by dendritic cells and macrophages, concentrated in lymph nodes, that dials the immune response down. In tumors it suppresses the T - cells that would otherwise attack cancer. Its immunosuppressive effect does not depend on the enzyme reaction it is named for. • Anti - PD - 1 therapy. Checkpoint inhibitors that release a brake on T - cells so they can recognize and kill tumor cells. Approved anti - PD - 1 drugs include pembrolizumab (Keytruda, Merck) and nivolumab (Opdivo, Bristol Myers Squibb). • Cold tumors. Tumors with few infiltrating T - cells, which makes them largely unresponsive to checkpoint inhibitors. Pancreatic, liver, and microsatellite - stable colorectal and esophageal cancers are common examples. • Tumor - draining lymph node. The lymph node that filters fluid from a tumor. It is where dendritic cells carry tumor fragments and where the anti - tumor immune response is first organized, which makes it the staging ground for any T - cell attack on the cancer. • Enzyme - independent mechanism. PLA2G2D is classified by its phospholipase activity, and the field has long assumed that activity accounts for its immunosuppressive role. Apeximmune tested an enzyme - dead form of the molecule and found that it retained potent immunosuppressive activity, establishing that PLA2G2D suppresses anti - tumor immunity through a function separate from its enzymatic one. AI - 306 blocks both. # # #