OS Therapies (OSTX) investor relations material

Investment highlights and market opportunity

• Over $300 million invested in the listeria immunotherapy platform, acquired in April 2025.

• Lead program OST-HER2 targets osteosarcoma with applications in breast and other solid tumors, addressing a $258B total addressable market.

• OST-HER2 peak annual global sales in osteosarcoma projected to exceed $1.5B.

• tADC platform offers a next-generation tunable drug conjugate with a patented silicone linker for improved safety and efficacy.

• Orphan, Fast Track, and Rare Pediatric Disease designations granted by FDA and EMA for OST-HER2.

Clinical pipeline and milestones

• OST-HER2 has shown positive Phase 2b data in osteosarcoma, with 71.2% 3-year overall survival vs. 45.8% for historical controls (p=0.002).

• Multiple candidates in clinical and preclinical stages for HPV cancers, NSCLC, glioblastoma, prostate, and breast cancer.

• Near-term milestones include regulatory submissions and Phase 3 trial initiation in Q4 2026, with potential FDA accelerated approval by Q1 2027.

• OST-HER2 also being developed for canine osteosarcoma, with commercialization targeted for 1H 2026.

Regulatory and commercialization strategy

• UK MHRA and EMA have accepted historical control as comparator for regulatory filings.

• Project Orbis pathway led by MHRA to drive international regulatory alignment and early market access.

• Commercial drug product launch expected in H2 2027, with a Priority Review Voucher valued at ~$200M upon approval.