Maintenance liposomal doxorubicin following induction doxorubicin in soft tissue sarcoma: A single-center observational study.

Abstract

e23568 Background: Maintenance chemotherapy prolongs progression-free survival (PFS) in several malignancies, but its role in soft tissue sarcoma (STS) remains unclear. Conventional doxorubicin is limited by cumulative toxicities. Liposomal doxorubicin offers a safer formulation and may enable prolonged therapy. Given the absence of prospective data, real-world evidence may inform feasibility and potential clinical benefit in STS. We evaluated outcomes of patients treated with maintenance liposomal doxorubicin following induction doxorubicin. Methods: This was a single-center retrospective study using the Quebec Sarcoma Registry (SaRC-Q) data from 2015 to 2025. Eligible patients had histologically confirmed STS and received doxorubicin-based induction therapy. Those achieving disease control, defined as stable disease, partial response or complete response, were subsequently treated with maintenance liposomal doxorubicin. Clinical variables included demographics, tumor characteristics, treatment details, adverse events, and outcomes. PFS and overall survival (OS) were analyzed using Kaplan-Meier estimates. Results: Twenty-four patients were included (median age 64 years; 62.5% male). The most frequent histologies were leiomyosarcoma and undifferentiated pleomorphic sarcoma (29.2% each). At diagnosis, 62.5% had localized disease and subsequently developed recurrent metastatic disease, while 37.5% presented with metastatic disease. Median induction exposure was six cycles. Maintenance liposomal doxorubicin was administered at 40 mg/m² every 28 days in 96% of patients for a median of 5 cycles (range, 1-19). Median PFS was 12.6 months (95% CI 10.4-14.8 months) and median maintenance PFS was 6.7 months (95% CI 4.2-9.2 months). Oligoprogression occurred in 20.8% of patients and was managed with local therapy. Commonly reported adverse events included anemia (21%) and fatigue (21%), with cardiac toxicity, cutaneous reactions, and peripheral edema each occurring in 8% of patients. Treatment was discontinued in 15 patients (62.5%) due to progression and in 2 patients (8.3%) due to adverse events, while 5 patients (20.8%) remained on therapy at data cutoff. Median OS was 60.3 months (95% CI 24.2-65.6 months). Conclusions: In this retrospective real-word cohort, maintenance liposomal doxorubicin appeared feasible, durable and well tolerated, with encouraging disease control in selected patients with advanced STS. These findings provide the first dedicated real-world evidence describing maintenance liposomal doxorubicin following induction doxorubicin and support prospective evaluation of anthracycline-maintenance strategies in STS.