- Chemotherapy =< 21 days prior to first administration of study treatment and/or monoclonal antibody =< 6 weeks prior to first administration of study treatment; immunotherapy, radiotherapy or experimental therapy within 28 days of first day of study drug dosing, or within six weeks of first day of study drug dosing in the event that nitrosoureas or mitomycin were used; concurrent systemic immunosuppressant therapy other than corticosteroids (e.g. cyclosporine A, tacrolimus, etc) must be discontinued within 28 days of the first dose of study drug