OS Therapies (OSTX) investor relations material

Executive summary

• Achieved statistically significant primary endpoint in Phase IIb trial for OST-HER2, with 75% two-year overall survival in treated patients versus 40% in historical controls; regulatory submissions planned in the US, UK, and EU in late 2025 and early 2026.

• Completed acquisition of HER2 and Lm-based immuno-oncology assets from Ayala, expanding pipeline and reducing future milestone and royalty obligations.

• Raised $7.1 million in PIPE financing, $6.4 million from warrant exercise inducement, and $7.8 million from warrant exercise for regulatory payments, supporting regulatory and pre-commercial activities and extending capital runway into late 2026.

• Revenue in 2026 expected from sale of Priority Review Voucher (PRV) upon regulatory approval; product launch delayed to 2027.

• Increased compassionate use requests for OST-HER2 from clinical trial sites.

Financial highlights

• Net loss of $15.3 million for the nine months ended September 30, 2025, compared to $5.9 million for the same period in 2024.

• Net operating loss of $6.879 million in Q3 2025, compared to $2.875 million in Q3 2024, due to pre-paid regulatory and pre-commercial expenses.

• Research and development expenses increased to $7.6 million from $2.0 million year-over-year, driven by clinical trial and regulatory activities.

• General and administrative expenses rose to $9.2 million from $1.9 million year-over-year, mainly due to advisory and marketing costs.

• Cash balance of $1.9 million as of September 30, 2025, with $1.5 million received after Q3 2025.

Outlook and guidance

• Plans to submit conditional MAA in the UK in December 2025, BLA in the US in January 2026, and MAA in the EU in Q1 2026 for OST-HER2.

• 2026 revenue expected from PRV sale; 2027 revenue to include US, UK, and EU product sales.

• Expects to incur increasing operating losses as development and regulatory activities accelerate.

• Current cash and proceeds expected to fund operations for 9-12 months; additional capital will be required.

• Platform designation for listeria immunotherapy to be sought once eligible.