Successful Ifosfamide Rechallenge in Soft-Tissue Sarcoma

Objectives: Treatment options for metastatic soft-tissue sarcomas are limited. The aim of this study was to investigate the clinical activity of ifosfamide rechallenge in synovial sarcoma (SS), liposarcoma (LPS), leiomyosarcoma (LMS), and high-grade sarcomas not otherwise specified. Methods: A retrospective search of the Royal Marsden Sarcoma Unit Database was performed to identify patients initially treated with ifosfamide (as single agent or in combination) and who were subsequently rechallenged with single-agent ifosfamide. Baseline demographics and response assessment were retrospectively obtained. Results: Sixty-seven patients were identified and the median age at diagnosis was 41 years (range, 18 to 71 y). There were 29 cases of SS, 17 of LPS, 12 of LMS, and 9 of sarcomas not otherwise specified. First-line ifosfamide-containing therapy was given to 14 patients as adjuvant therapy (adjuvant group) and 53 patients as palliative therapy (palliative group). Clinical activity (partial response or stable disease) with single-agent ifosfamide rechallenge was documented in 50.0% of patients in the adjuvant group (7 in the second line) and 34.0% of patients in the palliative group (15 in the second line, 1 in third line, and 2 in the fourth line). The median progression-free survival in patients with documented clinical activity was 11.5 months (95% CI, 8.8-12.3) and 6.9 months (95% CI, 5.1-9.0), respectively, in the adjuvant and palliative group. Ifosfamide rechallenge was mostly active in SS patients (49.3%, 14 out of 29 patients with partial remission or stable disease). Conclusions: Ifosfamide rechallenge has clinical activity in soft-tissue sarcoma and can be considered a viable option in treating metastatic disease.

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