COVD-23. PLANNED-USE GLUCARPIDASE FOR OUTPATIENT HIGH DOSE METHOTREXATE (HD-MTX) ADMINISTRATION IN PATIENTS WITH CNS LYMPHOMA (CNSL) DURING THE COVID-19 PANDEMIC

Infection with SARS CoV-2 virus has resulted in a global pandemic of COVID-19, a respiratory illness with a crude mortality rate of 3–4%. Risk of death is higher in the elderly and in patients with underlying comorbid conditions. When local incidence of COVID-19 is high, hospital resources are scarce and elective admissions and procedures are placed on hold. Patients with CNSL receiving first-line HD-MTX require admission for monitoring and aggressive hydration to prevent toxicity. This study explores the feasibility of planned-use glucarpidase, a recombinant bacterial enzyme that rapidly reduces serum MTX levels, to facilitate outpatient administration of HD-MTX. Eligible adult patients had isolated CNSL and had previously tolerated inpatient HD-MTX. MTX 3.5 g/m2 was administered in the outpatient setting with hydration. Patients returned 24 hours after MTX administration for glucarpidase 2000u and additional hydration. MTX level was determined by high pressure liquid chromatography (HPLC) 48 hours following MTX administration. To date, seven outpatient HD-MTX treatments have been administered to a total of three patients. In all cases, MTX levels were reduced to < 100 nmol/L at 48 hours. Three treatments resulted in grade 1 elevation of AST/ALT (two patients). One treatment resulted in a grade 2 creatinine increase. Creatinine returned to baseline following additional outpatient hydration. No patients required hospital admission. This study demonstrates feasibility of outpatient HD-MTX administration with planned-use glucarpidase during the COVID-19 pandemic. We are currently enrolling to a larger study of planned-use glucarpidase for repeated doses of outpatient HD-MTX.