 The biology and outcome of adult t(4;11)(q21;q23)/MLL-AFF1 acute lymphoblastic leukemia are poorly understood.     ///    "The clinical characteristics, therapy and outcome of 85 adults with acute lymphoblastic leukemia and t(4;11)(q21;q23)/MLL-AFF1 prospectively treated in the UKALLXII/ECOG2993 trial.. "