(P 371) CLINICAL PROFILE AND TREATMENT PATTERNS OF ANGIOSARCOMA IN THE REAL- WORLD SETTING: A SINGLE CENTER EXPERIENCE FROM 1991-2024.

Objective: Angiosarcoma (AS) has high rates of metastasis and mortality. It is considered more sensitive to novel therapies in clinical trials, including immune checkpoint inhibitors (ICI)and oncolytic viruses (OV), but data for patients (pts) who are not clinical trial candidates is lacking.

Methods: AS pts were identified via electronic medical records for retrospective analysis from1991 to December 2024. Pt and disease characteristics were analyzed. Kaplan-Meier method and Cox regression were used for survival analysis.

Results: Total of 129 pts were identified with median age 69 years, 51% male, 93% Caucasian,39% ECOG PS 0, 33% PS 1, 16% PS 2, 15% radiation related, and 30% de-novo metastasis. Of 129, 117 (91%) had received at least 1 modality of treatment; 77% received at least 1systemic therapy. Wound healing complications (WHC) were noted in 18 (19%) pts after local modality treatment. Of head/neck AS (n = 37), 42% who received (n = 26) and 9% who did not receive (n = 11) radiation had WHC. Of 90, 48% had 1-line, 23% 2-lines, 16% 3-lines, 9% 4-lines of systemic therapies. Of 90, 39 (43%) had ICI use at least once; with 67% in first-line,26% in second, 3% in third and 5% in fourth line. Of 129, 71% died and 29% were censored at the time of analysis. Median OS was 24.3 months (95% CI 17.7–33.4). Median OS for nonmetastatic pts was 33.4 months (95% CI 23.1–61.2) and 12.8 months (95% CI 5.5–25.2) for metastatic pts with p = 0.0016. Median OS in pts who received ICI did not differ by metastatic status (30.9 vs 27.6 months, p = 0.67). Univariate cox regression showed age, ECOG PS, visceral AS, de novo metastasis, radiation or systemic therapy as first modality as significant predictors of inferior survival; multivariate model showed age and PS as significant predictor of inferior survival in pts without metastasis; PS and visceral AS primary for metastatic pts. Though early use of ICI (1st and 2nd line) did not show statistical significance, they numerically had lower hazard ratio (HR) (0.59 and 0.78, respectively). Six pts received an OV (4 non-metastatic and 2 metastatic); 3 in 1st, 2 in 3rd and 1 in 4th line. Median OS was 30.8 months in pts receiving OVs.

Conclusion: AS continues to have poor overall survival outcomes. Early ICI use resulted in improved HR, although sample size was small. New treatments for AS are urgently needed.