Phase II study of neoadjuvant high-dose ifosfamide with concurrent radiotherapy followed by surgical resection in high-risk soft tissue sarcoma: A Spanish Group for Research on Sarcomas (GEIS) study.

Abstract

10052 Background: High-dose ifosfamide (HDI) has shown promising activity as single agent in first-line chemotherapy for advanced soft tissue sarcoma (STS). The purpose of this study was to assess the activity and toxicity of a preoperative doxorubicin-free regimen of HDI given concurrently with radiotherapy (RT) and followed by surgery in patients (pts) with localized high-risk STS. Methods: Pts with localized > 5 cm grade 2-3 and deep STS of the extremities and trunk wall, ≤65 years, no prior chemotherapy and ECOG PS 0-1 were enrolled in this multicenter phase II study. Pts received 3 cycles of preoperative HDI at a dose of 12 gr/m2 by continuous infusion over 5 days every 3 weeks, with mesna and prophylactic GCSF support, and concomitant external beam RT to a total dose of 50 Gy, followed by surgical resection. Postoperatively, pts with pathological response received 2 cycles of HDI and those with positive surgical margins 16 Gy of RT. The primary study endpoint was pathologic response (≥ 95% pathologic necrosis). A Simon 2-stage design (response rate P0=15%, P1=35%, α=0.10, β=0.10) required at least 2 responses in the first 17 pts to expand to a second cohort, and 7/32 responses to be considered of positive. Results: From March 08 to December 10, 34 pts were included. Two pts were ineligible. Median age was 54 (18-65). Tumor location was extremity (28 pts) and trunk wall (4). Preoperative planned treatment was completed in 87.5% pts. HDI was completed in 87.5% pts while RT in 94% pts. Grade 3-4 toxicities included neutropenic fever (3 pts), anemia (4), asthenia (2), infection (2) and radiation dermatitis (2). 31 pts underwent surgery: 27 were R0 resections, of which 2 were amputations, and 4 were R1 resections. Pathologic response was ≥ 95% necrosis in 9 pts (28%) and 50%-94% necrosis in 12 pts. After a median follow-up of 21 months, estimated 2-year rates for disease-free survival and overall survival were 58% (95%CI, 40%-77%) and 77% (95%CI, 61%-93%), respectively. Conclusions: Preoperative treatment with HDI given concurrently with RT in pts with high-risk STS is feasible and safe, yielding promising pathologic response rates.