(P 115) SINGLE-CENTER EXPERIENCE WITH TYROSIN KINASA INHIBITORS IN ADVANCED BONE SARCOMA: EFFICACY AND SAFETY OUTCOMES

Objective: Tyrosine kinase inhibitors (TKIs) have emerged as potential therapeutic options for refractory osteosarcoma and Ewing sarcoma. However, clinical experience remains limited, and outcomes are variable.

Methods: We conducted a retrospective analysis of patients with primary advancedbone sarcomas treated with TKIs at our institution between December 2013 and March 2025. Primary endpoints included progression-free survival (PFS) with different TKIs and objective response rate (ORR).

Results: Twenty-eight patients were included (18 osteosarcoma, 4 Ewing sarcoma, 1 Ewing sarcoma-like, and 5 other sarcoma histologies). Median age was 28 years (range 13–55). Fifty-three percent of the patients were male. The majority of patients had received more than two prior lines of therapy (57.1%). TKIs used included sorafenib (n=17, 60.7%), cabozantinib (n=5, 17.9%), regorafenib (n=4, 14.3%), and pazopanib (n=2, 7.1%). Median progression-free survival (PFS) with all TKIs was 4 months (95% CI: 1.3–6.4), with better outcomes observed with cabozantinib (median PFS 4 months, 95% CI: 2.8–5.1) and pazopanib (median PFS 10 months, though only 2 patients). Cabozantinib achieved the highest ORR (66.7% stable disease [SD] and 33.3% partial responses [PR]), with a disease control rate of 100%. The observed toxicities were consistent with those reported in clinical trials.

Conclusion: Our experience confirms the modest activity of TKIs in refractory bone sarcomas, with similar PFS rates across all drugs. Cabozantinib appears to have the highest disease control rates and a more favorable toxicity profile, as reported in the literature.