Isolated salivary gland extramedullary relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia during blinatumomab treatment

Excerpt

A 15-year-old boy diagnosed with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) achieved molecular complete remission (MCR) with a combination of conventional chemotherapy and dasatinib. During maintenance therapy, the patient presented with dasatinib-induced hemorrhagic colitis and was switched from dasatinib to imatinib. Ten months after completion of maintenance therapy, minor BCR/ABL transcripts were detected in peripheral blood mononuclear cells, using in-house nested PCR. The transcript was not detected by conventional quantitative real-time PCR (Q-PCR) two months after we employed a watchful waiting strategy with resumption of imatinib. However, ten months later, the transcript level in the bone marrow increased to a level detectable by Q-PCR for the first time. Therefore, we strongly recommended allogeneic hematopoietic cell transplantation (allo-HSCT). The patient was switched from imatinib to ponatinib during the search for an unrelated matched donor. However, hematological relapse accompanied by BCR-ABL T315I and F486S mutations was detected two months later. Lumbar puncture revealed no blasts in the cerebrospinal fluid. Computed tomography of the head and whole body revealed no extramedullary disease. …