Sepsis in Neutropenic Patients: Autologous Stem Cell Transplantation as Model: a Transcriptomic Approach.

Treatment of cancer, and more particularly of haematological malignancies, partly relies on chemotherapy. Most therapeutic regimens display various toxicities, one of the most common being haematological toxicity, affecting the three lineages. While anaemia and thrombopenia can be overcome by haematological growth factors and transfusion, one of the most severe life-threatening toxicity is sepsis that develops during neutropenia. Neutropenia, despite the use of granulocyte colony-stimulating factors (G-CSF) and antibiotics, is still a major limitation in chemotherapy which is responsible for the majority of treatment-related morbidity and mortality and for prolonged hospitalisation.

In neutropenic patients, sepsis is more frequent and more severe than in non-neutropenic patients. While the occurence of neutropenia and sepsis is often unpredictable and thus difficult to study in a prospective way, stem cell transplantation represents a quite convenient model to study such a question. Autologous stem cell transplantation indications in haematology are mainly multiple myeloma and relapsed lymphoma or Hodgkin disease. Briefly, after a mobilization procedure, a graft of patient's hematopoietic stem cells is collected by cytapheresis and frozen. When the patient has reached complete remission by conventional chemotherapy, he benefits from a very high dose myeloablative chemotherapy (called "conditioning regimen"). The "conditioning regimen" targeted to have high antitumoral activity leads to a "cytokine storm" resulting in a "programmed inflammation". 36 hours after the lasting of the conditioning regimen, the CD34+ cells are thawed and infused to the patient. Thus neutropenia usually begins at D4 post transplantation and lasts for 10 days, until graft becomes "functional". Thus, the timing and duration of neutropenia are very homogeneous. During neutropenia, fever and sepsis are very frequent (>80% patients), thus, most patient will be informative regarding sepsis, and there is an easy possibility of biological sampling before" programmed inflammation" (due to conditioning regimen), after inflammation before sepsis, then during and after the sepsis. Since the patient is hospitalized, the kinetic monitoring is quite easy