Doripenem versus meropenem as first-line empiric therapy of febrile neutropenia in patients with acute leukemia: a prospective, randomized study.

Febrile neutropenia is often observed in patients with hematologic malignancies, especially in those with acute leukemia. Meropenem has potent and broad antibacterial activity against gram-positive and gram-negative bacteria, and is recommended as first-line empiric therapy for febrile neutropenia. In contrast, the safety and efficacy of doripenem in patients with febrile neutropenia and hematologic malignancies is limited. In this randomized, prospective, cooperative, open-label trial, we compared doripenem (1.0 g every 8 h) to meropenem (1.0 g every 8 h) as first-line empiric antibacterial treatment of febrile neutropenia. To evaluate efficacy and safety, 133 hospitalized patients with acute leukemia or high-risk myelodysplastic syndrome, who developed febrile neutropenia during or after chemotherapy, were randomized to each drug. Resolution of fever within 3 to 5 days without treatment modification (i.e., the primary endpoint) did not significantly differ between the doripenem and meropenem groups (60.0% vs. 45.6%, respectively; P = 0.136). However, resolution of fever within 7 days of treatment was significantly higher in the doripenem group than in the meropenem group (78.4% vs. 60.2%, respectively; P = 0.037). Similar rates of adverse events (grades 1-2) were observed in both groups. Thus, we conclude that both drugs are safe and well-tolerated for the treatment of febrile neutropenia in patients with acute leukemia or high-risk myelodysplastic syndrome, and that the clinical efficacy of doripenem is noninferior to that of meropenem. UMIN Clinical Trial Registry number: 000006124.

Successful cord blood transplantation in an adult acute lymphoblastic leukemia patient with congenital heart disease.

Recent advances in surgical corrections and supportive care for congenital heart disease have resulted in increasing numbers of adult survivors who may develop hematological malignancies. Treatments including chemotherapy for such patients may cause serious hemodynamic or cardiac complications, especially in those receiving stem cell transplantation. We present a 29-year-old woman with acute lymphoblastic leukemia and congenital heart disease. She had been diagnosed with pulmonary atresia with an intact ventricular septum at birth, and the anomaly was surgically corrected according to the Fontan technique at age 9 years. Her induction chemotherapy required modifications due to poor cardiac status with Fontan circulation. However, after surgical procedures including total cavopulmonary connection and aortic valve replacement at first complete remission, her cardiac status was significantly improved. Subsequently, she underwent cord blood stem cell transplantation at the third complete remission. She required intensive supportive care for circulatory failure as a pre-engraftment immune reaction and stage III acute graft versus host disease of the gut, but recovered from these complications. She was discharged on day 239, and remained in complete remission at 1-year post-transplantation.

Bortezomib induces thrombocytopenia by the inhibition of proplatelet formation of megakaryocytes.

Bortezomib is a potent proteasome inhibitor that has been extensively used to treat multiple myeloma. One of the most common grade 3 adverse events is cyclic thrombocytopenia. In this study, we studied the mechanism by which bortezomib induces thrombocytopenia in a mouse model. After the intravenous administration of bortezomib (2.5 mg/kg) via tail vein, platelet counts significantly decreased on days 2-4 and recovered to the normal range on day 6. Bortezomib (2.5 mg/kg) injected into mice in vivo did not affect colony-forming unit-megakaryocytes (CFU-Mk) or megakaryocytes in the bone marrow. However, proplatelet formation (PPF) significantly decreased on days 2 and 4, after bortezomib administration to mice. Meanwhile, CFU-Mk formation and the ploidy distribution of cultured megakaryocytes in vitro were not affected by bortezomib used at concentrations of ≤ 1 ng/mL. The PPF of megakaryocytes in vitro significantly decreased with 0.1, 1, 10, and 100 ng/mL bortezomib. Considering the bortezomib concentration in clinical studies, these data strongly suggest that decreased PPF activity induces thrombocytopenia. To elucidate the mechanism behind decreased PPF, Western blot was performed. Activated Rho expression increased after the incubation of murine platelets with bortezomib. Decreased PPF activity was eliminated by the addition of Y27632, a Rho kinase inhibitor, in vitro. Given that the Rho/Rho kinase pathway is a negative regulator of PPF, bortezomib increases activated Rho, inducing decreased PPF, which results in decreased platelet count.