TREATMENT OF HUMAN B-CELL PRECURSOR LEUKEMIA IN SCID MICE USING A COMBINATION OF THE INVESTIGATIONAL BIOTHERAPEUTIC AGENT B43-PAP WITH CYTOSINE-ARABINOSIDE

Combined immunochemotherapy regimens using the investigational biother apeutic agent B43(anti-CD19)-pokeweed antiviral protein (PAP) immunoto xin may offer an effective treatment for refractory B-cell precursor l eukemias. The purpose of the present study was to explore and identify effective combinations of B43-PAP with standard chemotherapeutic drug s, including the anthracyclin doxorubicin, the epipodophyllotoxin etop oside, the nitrosurea carmustine, and the antimetabolite cytosine arab inoside. Here, we report that the B43-PAP plus cytosine arabinoside co mbination has potent antileukemic activity against human B-cell precur sor leukemia in SCID mice and leads to 100% long-term event-free survi val from an otherwise invariably fatal leukemia. Surprisingly, none of the other treatment protocols tested, including combinations of B43-P AP with carmustine, doxorubicin, or etoposide, proved more effective t han B43-PAP alone.