WASHINGTON - Drug regulators have called for more trials to establish the optimal hemoglobin target for use of erythropoiesis-stimulating agents (ESAs), such as Amgen Inc.'s Aranesp (darbepoetin alfa) and Epogen (epoetin alfa) and Centocor Ortho Biotech Inc.'s Procrit (epoetin alfa), in treating anemia in patients with chronic kidney disease. (BioWorld Today)