The clinical impact of antibacterial prophylaxis and cycling antibiotics for febrile neutropenia in a hematological malignancy and transplantation unit.

Febrile neutropenia is an expected complication during treatment of aggressive hematological malignancies and hematopoietic cell transplantation. We conducted a prospective cohort trial to determine the effects and safety of prophylactic fluoroquinolone administration, and rotation of empiric antibiotics for neutropenic fever in this patient population. From March 2002 through 2004, patients were treated with prophylactic levofloxacin during prolonged neutropenia, and a cycling schedule of empiric antibiotic therapy for neutropenic fever was initiated. The rates of bacteremia, resistance and complications were compared to a retrospective cohort of previously treated patients. The rate of gram-negative bacteremia decreased after the initiation of prophylactic levofloxacin (4.7 vs 1.8 episodes/1000 patient days, P<0.05). Gram-positive bacteremia rates remained unchanged, but more isolates of Enterococcus faecium were resistant to vancomycin after the intervention began. Resistance to the antibiotic agents used in the rotation did not emerge. There was no change in mortality during the intervention period. A prophylactic and cycling antibiotic schedule was successfully implemented on a hematological malignancy and hematopoietic cell transplant unit. gram-negative bacteremia was significantly decreased, without emergence of resistance. Concerns with Gram-positive resistance will require further observation.

Thiotepa and fractionated TBI conditioning prior to allogeneic stem cell transplantation for advanced hematologic malignancies: a phase II single institution trial.

Relapse of hematologic malignancies after allogeneic stem cell transplantation remains a common problem, in particular for patients who have advanced disease at the time of transplantation. Thiotepa has excellent antileukemic and immunosuppressive activity, and could therefore be a useful drug in the conditioning regimen for patients with advanced hematologic neoplasms. We retrospectively analyzed toxicity, engraftment and survival data of 41 patients who received a conditioning regimen of thiotepa (600 mg/m2) and hyperfractionated TBI (10 Gy) prior to matched related (n = 25) or matched unrelated (n = 16) allogeneic stem cell transplantation. The mean age at transplantation was 37.8 years (range 20-59), all but five patients had advanced hematologic malignancies at the time of transplantation. GVHD prophylaxis was with standard cyclosporine and methotrexate. Engraftment was excellent, but the regimen was associated with a high incidence of grade III renal (41%) and hepatic (15%) toxicity, and high transplant-related mortality (44% at day +90). The 3-year event-free survival was 13% and overall survival 14%. We conclude that this regimen requires modification to reduce toxicity.

Hematopoietic stem cell transplantation in hematologic malignancy.

Hematopoietic stem cell transplantation has become increasingly important in the treatment of hematologic malignancies over the past 20 years. While it is associated with significant morbidity, it offers the only chance of cure in many circumstances. Autologous and allogeneic transplantation have been used successfully to treat a variety of hematologic malignancies. These 2 approaches offer different risks and benefits which are discussed in this review. Timing of transplantation and selection of patients are also discussed. New innovations in stem cell transplantation including umbilical cord blood and non-myeloablative transplantation are reviewed.

Molecular chaperone GRP94 binds to the Fanconi anemia group C protein and regulates its intracellular expression.

The FAC protein encoded by the gene defective in Fanconi anemia (FA) complementation group C binds to at least three ubiquitous cytoplasmic proteins in vitro. We used here the complete coding sequence of FAC in a yeast two-hybrid screen to identify interacting proteins. The molecular chaperone GRP94 was isolated twice from a B-lymphocyte cDNA library. Binding was confirmed by coimmunoprecipitation of FAC and GRP94 from cytosolic, but not nuclear, lysates of transfected COS-1 cells, as well as from mouse liver cytoplasmic extracts. Deletion mutants of FAC showed that residues 103-308 were required for interaction with GRP94, and a natural splicing mutation within the IVS-4 of FAC that removes residues 111-148 failed to bind GRP94. Ribozyme-mediated inactivation of GRP94 in the rat NRK cell line led to significantly reduced levels of immunoreactive FAC and concomitant hypersensitivity to mitomycin C, similar to the cellular phenotype of FA. Our results demonstrate that GRP94 interacts with FAC both in vitro and in vivo and regulates its intracellular level in a cell culture model. In addition, the pathogenicity of the IVS-4 splicing mutation in the FAC gene may be mediated in part by its inability to bind to GRP94.

Paroxysmal nocturnal hemoglobinuria: new insights from murine Pig-a-deficient hematopoiesis.

A large fraction of the hematopoietic cells of patients with paroxysmal nocturnal hemoglobinuria (PNH) are deficient in membrane expression of glycosylphosphatidylinositol-anchored proteins (GPI-APs). Current evidence suggests that this deficiency is sufficient to account for the hemolytic and thrombotic manifestations of this disease but not for its frequent association with aplastic anemia, an autoimmune disorder in which the patients' own hematopoietic progenitor cells are the target. Mutations in X-linked gene PIG-A, encoding one of several enzymes required for the biosynthesis of the glycophosphatidylinositol anchor, have been found in all PNH patients studied to date. Recent experiments with murine Pig-a knock-out embryonic stem cells show that although embryogenesis is critically dependent on normal GPI-AP expression, Pig-a-deficient cells can undergo apparently normal hematopoietic differentiation if they develop in a GPI-AP-replete environment. Thus, in an in vitro mouse model of PNH, Pig-a mutations confer no gross proliferative or differentiative advantage or disadvantage, suggesting an unidentified process selecting for these mutations in the bone marrow of patients with the PNH-aplastic anemia syndrome. The rescue of hematopoiesis observed in chimeric cultures of knock-out and normal cells was accompanied by intercellular transfer of GPI-AP, suggesting exciting new possibilities for future therapeutic manipulations in PNH patients.