EURAMOS-1 MAP Chemotherapy Regimen for Resectable High-Grade Osteosarcoma
The standard EURAMOS-1 MAP regimen for patients ≤40 years with resectable high-grade osteosarcoma consists of high-dose methotrexate (12 g/m²), doxorubicin (75 mg/m²), and cisplatin (120 mg/m²) administered in a specific sequence over approximately 29 weeks. 1
Preoperative Phase (Weeks 0-10)
The neoadjuvant component includes two 5-week cycles before surgery:
- Methotrexate: 12 g/m² IV over 4 hours (given twice per cycle, typically weeks 0,1,5,6)
- Cisplatin: 120 mg/m² IV (weeks 3,8)
- Doxorubicin: 37.5 mg/m²/day IV for 2 consecutive days (total 75 mg/m² per cycle; weeks 3,8)
- Leucovorin rescue: 15 mg orally every 6 hours for 10 doses starting 24 hours after methotrexate infusion 2
This preoperative chemotherapy was completed according to protocol in 94% of patients in the EURAMOS-1 trial 1.
Surgery
Definitive surgical resection is performed after completion of neoadjuvant chemotherapy, with histologic response assessment determining subsequent treatment.
Postoperative Phase
For Good Responders (<10% viable tumor):
Four additional cycles of MAP (two full MAP cycles + two MA cycles without methotrexate) 3:
- Continue the same MAP regimen for 2 cycles
- Follow with 2 cycles of doxorubicin and cisplatin only (MA)
- Total treatment duration: approximately 29 weeks from start
Critical finding: Adding pegylated interferon alfa-2b to MAP in good responders did NOT improve event-free survival (HR 0.83,95% CI 0.61-1.12, P=0.214) and is not recommended 3.
For Poor Responders (≥10% viable tumor):
Continue with MAP alone postoperatively. The EURAMOS-1 poor response trial definitively showed that adding ifosfamide and etoposide (MAPIE regimen) provided no survival benefit (HR 0.98,95% CI 0.78-1.23) but significantly increased toxicity, including more grade 4 non-hematological toxicity (24% vs 12%) and febrile neutropenia (73% vs 50%) 4. This establishes MAP as standard of care even for poor responders 5.
Dosing Schedule from FDA Label
The methotrexate FDA label provides the specific EURAMOS-based schedule 2:
| Drug | Dose | Treatment Weeks After Surgery |
|---|---|---|
| Methotrexate | 12 g/m² IV over 4 hours | 4,5,6,7,11,12,15,16,29,30,44,45 |
| Leucovorin | 15 mg PO q6h × 10 doses | Starting 24h after MTX |
| Doxorubicin (single) | 30 mg/m²/day × 3 days | 8,17 |
| Doxorubicin + Cisplatin | 50 mg/m² + 100 mg/m² | 20,23,33,36 |
Age-Specific Considerations
For patients >40 years: High-dose methotrexate (8 g/m²) can be challenging to administer. Alternative regimens combining doxorubicin, cisplatin, and potentially ifosfamide are acceptable options 6. However, recent data suggests that when MAP is used in older adults, treatment completion rates drop significantly (22% in ≥40 years vs 72% in pediatric patients), primarily due to delayed methotrexate elimination 7.
Critical Safety Requirements
When administering high-dose methotrexate 2:
- Use preservative-free formulation only (benzyl alcohol-containing formulations are contraindicated for high-dose therapy)
- Monitor methotrexate levels to ensure peak concentration of 1,000 micromolar at end of infusion
- If inadequate levels achieved, escalate dose to 15 g/m² in subsequent cycles
- Ensure adequate hydration and urinary alkalinization
- Monitor renal function closely (methotrexate elimination is reduced in renal impairment, ascites, or pleural effusions)
Expected Toxicity Profile
Grade 3-4 toxicities from the EURAMOS-1 trial 1:
- Neutropenia: 83% of cycles
- Infection during neutropenia: 59% of cycles
- Treatment-related mortality: 0.13% during preoperative phase
Outcomes
- Good responders: 3-year event-free survival 76% (95% CI 72-79%)
- Poor responders: Outcomes remain inferior despite treatment intensification
- Histologic response rate: 50% achieve ≥90% necrosis
The EURAMOS-1 trial definitively established that MAP remains the standard backbone regimen, and attempts to intensify therapy based on histologic response have failed to improve outcomes 6, 5, 4.