Amgen Inc on Thursday said some patients with a deadly form of leukemia experienced complete remission after being treated with its Blincyto drug in a midstage clinical trial, results that could eventually lead to an expanded approval of the pricy cancer medicine. While providing few details, the world's largest biotechnology company said the drug, which helps the immune system to fight cancer, induced complete remission or complete remission with partial hematological recovery in a "clinically meaningful number of patients" with relapsed or refractory Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia .