(P 321) COMPARATIVE ANALYSIS OF FIRST-LINE DOXORUBICIN-BASED COMBINATION REGIMENS IN METASTATIC LEIOMYOSARCOMA: IMPACT ON SURVIVAL AND DISEASE CONTROL

Objective: First-line chemotherapy is crucial in the management of metastatic leiomyosarcoma; however, limited comparative data exist for approved combination regimens. This study examines progression-free survival (PFS), overall survival (OS), treatment sequencing, and safety profiles to determine optimal therapeutic strategies.

Methods: We retrospectively analyzed 73 metastatic leiomyosarcoma patients (2011–2024), assessing demographics, tumor features, treatments, and outcomes including response rates, PFS, PFS2, and OS using Kaplan-Meier analysis.

Results: The cohort (86% female, median age 54) included 42% uterine primaries and 50% metastatic cases. First-line regimens were mainly doxorubicin + dacarbazine (27%) and doxorubicin + trabectedin (24%). Doxorubicin + dacarbazine had the longest median PFS (12 months), followed by doxorubicin + trabectedin (8 months). PFS differences showed a non-significant trend (p=0.07), and median OS was similar across regimens (33 months, p=0.9).Doxorubicin + DTIC showed the highest disease control rate at 86.4%, indicating superior stabilization.
Second-line PFS is longer (12 months) in patients treated first with doxorubicin + trabectedin followed by gemcitabine + dacarbazine, compared to those starting with doxorubicin + dacarbazine followed by trabectedin (5 months).
Excluding uterine leiomyosarcomas, first-line PFS is longer with doxorubicin + trabectedin (18 months) than doxorubicin + dacarbazine (13 months), but not statistically significant (p=0.6).

Conclusion: Doxorubicin + dacarbazine showed the longest first-line PFS and highest disease control rate, though overall survival was similar across regimens.
Second-line PFS was longer when doxorubicin + trabectedin was used first.
Excluding uterine leiomyosarcomas, doxorubicin + trabectedin showed a non-significant PFS advantage over doxorubicin + dacarbazine

Descriptive analysis