OS Therapies (OSTX) investor relations material

Executive summary

• Completed submission of Phase 2b clinical and biomarker data for OST-HER2 to the FDA for a Pre-BLA meeting, with similar filings planned for EMA and MHRA in April 2026.

• Achieved regulatory alignment on immune biomarkers as surrogate efficacy endpoints, supporting accelerated approval pathways in the U.S., Europe, and U.K.

• OST-HER2 demonstrated statistically significant event-free survival and overall survival in recurrent, fully resected, pulmonary metastatic osteosarcoma.

• Acquired listeria monocytogenes immunotherapy platform, eliminating $20 million in milestone payments and reducing net royalties to 1.5%.

• OST-HER2 received multiple regulatory designations, including Orphan Drug, Fast Track, and Rare Pediatric Disease from FDA and EMA.

Financial highlights

• Recorded a net operating loss of $28.75 million for 2025, compared to $8.82 million in 2024, primarily due to increased R&D and administrative expenses.

• Net loss per share was $0.98 in 2025 on 290.235 million weighted average shares, versus $1.28 per share in 2024 on 6.950 million shares.

• Raised $5.5 million in capital during the first quarter of 2026.

Outlook and guidance

• Expects Pre-BLA meeting with FDA in May 2026 and to initiate confirmatory Phase 3 trial in Australia in Q3 2026.

• Anticipates receiving BLA under Accelerated Approval in the U.S. and Conditional Marketing Authorizations in Europe and U.K. in the second half of 2026.

• Plans to sell a Priority Review Voucher if BLA is granted, referencing a recent PRV sale at $205 million, though actual proceeds are uncertain.