TY - JOUR T1 - Effects of PIXY321, a granulocyte-macrophage colony-stimulating factor/interleukin 3 fusion protein, on human tumor colony-forming units taken directly from patients. JF - Clinical Cancer Research JO - Clin Cancer Res SP - 1713 LP - 1716 VL - 2 IS - 10 AU - Izquierdo, M A AU - Degen, D AU - Raymond, E AU - Caron, D AU - Ortiz, V AU - Banks, P AU - Von Hoff, D D Y1 - 1996/10/01 UR - http://clincancerres.aacrjournals.org/content/2/10/1713.abstract N2 - PIXY321, a granulocyte-macrophage colony-stimulating factor/interleukin 3 (GM-CSF/IL-3) genetically engineered hybrid, has shown greater biological activity in stimulating committed myeloid progenitors than either GM-CSF or IL-3 in vitro, in vivo, and in patients treated with high-dose chemotherapy. However, one concern is that PIXY321 may stimulate the proliferation of malignant cells which have functional GM-CSF or IL-3 receptors. Therefore, using a human tumor cloning assay, we have tested the effects of several concentrations of PIXY321 ranging from 0.1 to 100 ng/ml on tumor cells taken directly from 98 patients with solid tumors and Hodgkin's or non-Hodgkin's lymphomas. Of the 34 evaluable specimens, including 15 breast cancers, 5 ovarian cancers, 5 lung cancers, and 9 lymphomas, none showed stimulation of tumor growth. Interestingly, a significant inhibition of the tumor proliferation was seen in one breast cancer and in one large cell immunoblastic non-Hodgkin's lymphoma after continuous exposure of PIXY321. In conclusion, the use of PIXY321 to reduce myelosuppression after high-dose chemotherapy appears unlikely to result in stimulation of the growth of malignant cells in patients with lymphoma or cancers of the breast, lung, and ovary. ER -