Ambulatory High-dose Methotrexate Administration in Pediatric Osteosarcoma Patients at a Single Institution in Argentina.

Abstract

The purpose of this study was to evaluate the feasibility and safety of ambulatory high-dose methotrexate (HDMTX) administration with oral hydration, alkalinization, and leucovorin rescue. HDMTX (12 g/m) was given intravenously over 4 hours after urine alkalinization. Families and patients were instructed to continue ambulatory oral hydration and alkalinization to monitor urine pH and to adjust bicarbonate according to our institution's treatment algorithm. Clinical status and MTX levels were controlled every 24 hours, and oral leucovorin dose was adjusted accordingly. From April 2007 to December 2010, 150 of 447 courses of HDMTX (31.4%) were given on an outpatient basis, and 91.2% were successfully completed. The main causes of failure were poor oral tolerance (n=6) and fever (n=4). Most patients (81%) had MTX levels of <10 μmol/L 24 hours post-HDMTX; only in 1 course the levels were >50 μmol/L (50.96 μmol/L). Neutropenia grade III/IV was observed in 18.3% of the courses, grade III/IV leukopenia in 2.7%, and grade III/IV thrombocytopenia and anemia in 4.7%. Around 39% were associated with grade III/IV hepatic toxicity (asymptomatic hypertransaminasemia), grade III-IV gastrointestinal toxicity (vomiting and diarrhea) (5%), grade III-IV mucositis (4%), and none of the patients developed renal toxicity. Ambulatory HDMTX administration is feasible and safe in a population with poor resources in a developing country.