A 77-year-old man diagnosed with mixed-phenotype acute
leukemia (MPAL (B/Myeloid), NOS) achieved complete remission (CR) after eight courses of hyper-CVAD/MA
therapy. However, 6 months later, blasts were observed on peripheral blood smear, and bone marrow aspiration revealed that the disease had relapsed as B
lymphoblastic leukemia (ALL). At this time, he had left
pleural effusion. He received two courses of
inotuzumab ozogamicin (InO) and achieved second hematological CR, but the left
pleural effusion worsened over time, suggesting poor disease control. After changing the regimen to
blinatumomab, aspiration biopsy cytology showed that the blasts in the pleural fluid disappeared and respiratory distress improved after one course of treatment. Flow cytometry results showed increased populations of CD3-positive T-cells, suggesting that
blinatumomab may have migrated into the pleural fluid and exerted an antitumor effect. Although new ALL-specific antibody drugs, such as InO and
blinatumomab, are expected to improve prognosis, only few reports have described their tissue migration. The difference between InO and
blinatumomab in terms of efficacy of treating
malignant pleural effusion remains unclear and should be explored in additional cases.