The standard treatment of osteosarcoma includes cisplatin and high-dose methotrexate (HDMTX); both agents exert significant toxicity, and HDMTX requires complex pharmacokinetic monitoring and leucovorin rescue. In the previous OS91 trial, the treatment of localized disease with carboplatin, ifosfamide, doxorubicin, and HDMTX yielded outcomes comparable to those of cisplatin-based regimens and caused less toxicity. To build on this experience, the authors conducted a multi-institutional trial (OS99) that evaluated the efficacy of carboplatin, ifosfamide, and doxorubicin without HDMTX in patients with newly diagnosed, localized, resectable osteosarcoma.

Treatment was comprised of 12 cycles of chemotherapy administered over 35 weeks: 3 cycles of carboplatin (dose targeted to area under the concentration-time curve of 8 mg/mL × min on Day 1) and ifosfamide (at a dose of 2.65 g/m(2) daily ×3 days) and 1 cycle of doxorubicin (at a dose of 25 mg/m(2) daily ×3 days) before surgical resection, followed by 2 additional cycles of the combination of carboplatin and ifosfamide and 3 cycles each of doxorubicin (25 mg/m(2) daily ×2 days) combined with ifosfamide or carboplatin.

A total of 72 eligible patients (median age, 13.4 years) were enrolled between May 1999 and May 2006. Forty of the 66 (60.6%) evaluable patients had good histologic responses (>90% tumor necrosis) to preoperative chemotherapy. The estimated 5-year event-free survival rate was 66.7% ± 7.0% for the OS99 trial compared with 66.0% ± 6.8% for the OS91 trial (P = .98). The estimated 5-year survival rate was 78.9% ± 6.3% for the OS99 trial and 74.5% ± 6.3% for the OS91 trial (P = .40).

The regimen used in the OS99 trial was found to produce outcomes comparable to those of cisplatin-containing or HDMTX-containing regimens. This therapy offers a good alternative for patients, particularly those who demonstrate an intolerance of HDMTX, and for institutions that cannot provide pharmacokinetic monitoring for MTX.