9563 Objectives: The current first line standard chemotherapy for advanced soft-tissue sarcomas is the combination of doxorubicine and ifosfamide. Liposomal encapsulation is a strategy pursued to reduce toxicity and improve tumor uptake. There are so far only limited systematic data regarding the efficacy of liposomal anthracyclines in advanced soft-tissue sarcomas. We have previously reported on a phase II study with liposomal daunorubicine (L-Dauno) with ifosfamide, named IDx1. Here we report on an additional cohort of the phase II study using liposomal doxorubicine (L-Doxo). Methods: In a single-arm two cohort phase II study 55 patients with advanced soft-tissue sarcoma had received first line a maximum of 6 cycles (median 2 cycles) of ifosphamide (5 g/m2) and in cohort 1 L-Dauno (100 mg/m2, 40 patients) or in cohort 2 the approximate equivalent of L-Doxo (75 mg/m2, 15 patients). Cycles were repeated every 4 weeks in absence of disease progression. Primary study endpoint was response rate. Results: The overall response rate was 25% (n = 14). In the L-Dauno group the results were as follows: CR 3% (n = 1), PR 29% (n = 10), SD 17% (n = 6), PD 37% (n = 13), NED or intermittent death 14% (n = 5), and in the L-Doxo group: PR 20% (n =3), SD 26% (n =4) and PD 53% (n = 8). Interestingly, all three liposarcoma patients (two in the L-Dauno group, one in the L-Doxo group) responded, whereas liposarcoma usually carries a poor response rate. For both combinations toxicity was similarly tolerable with short episodes of hematotoxicity (leucocyte nadir on day 9, platelet nadir on day 11), 11 febrile episodes, no grade 3 or 4 mucositis, no cardiac toxicity and 5 episodes of grade 2 acute ifosfamide-related CNS-toxicity. Based on the hematotoxicity kinetics, three weekly regimens appear feasible. Conclusion: The combination of liposomal anthracyclines and ifosfamide is a safe and effective first line regimen in the treatment for advanced soft tissue sarcoma. Further evaluation in a randomized trial will be pursued. The unexpected high responsiveness of liposarcoma warrants further phase II investigation. 1Siehl JM et al. Cancer 2005. No significant financial relationships to disclose.
