[Blinatumomab-based combination treatment for CD19-positive acute leukemia of an ambiguous lineage]

Acute leukemia of ambiguous lineage (ALAL) is a rare type of acute leukemia and is extremely difficult to treat. Here, we present six patients with CD19-positive ALAL who were successfully treated with blinatumomab-based combination treatment in the front-line setting. Five were diagnosed with B-cell/myeloid mixed phenotype acute leukemia (MPAL) and one with B-cell/T cell MPAL. All six patients achieved complete remission after one cycle of blinatumomab combination treatment. Furthermore, 3 (50%) patients achieved MRD-negative (<0.01%) by flow cytometry and 2 (50%) of four patients with evaluable molecular MRD achieved molecular remission. At some point during the treatment, 5 (83.3%) patients achieved MRD negativity and all four patients with evaluable molecular MRD had molecular remission. The overall survival was 100%, and the event-free survival was 83.3% after a median follow-up time of 15 months. This study provides preliminary evidence that blinatumomab-based combination therapy is an effective and safe treatment for patients with CD19-positive ALAL in the front-line setting.