Abstract
Abstract 1329
Chronic granulomatous disease (CGD) is a congenital disorder resulting from decreased or absent oxidase production by neutrophils. As a result, patients with CGD are prone to bacterial and fungal infections and have a shortened life expectancy. Hematopoietic stem cell transplantation (HSCT) can be curative, and patients are increasingly referred for transplant due to an ongoing infection not amenable to cure using standard treatments. The use of granulocyte transfusions has been described in patients undergoing transplant with an underlying infection at the time of conditioning, but reports are limited to single cases. We describe here the effects of granulocyte transfusions in four patients undergoing either an HLA matched sibling or unrelated donor HSCT, using an alemtuzumab containing regimen and sirolimus as GVHD prophylaxis. Age of the patients was 6 to 25 (mean 11.5) yrs, and weight was 15.3 to 54 (mean 27.5) kg. Three of the patients had persistent Aspergillus infection involving the spine, lung, and/or brain despite long term combination antifungal therapy including a triazole, echinocandin and/or amphotericin. The fourth patient had an Actinomyces pneumonia progressive on combination antibacterial treatment. None of the patients had detectable HLA antibodies prior to the transfusions, and none received G-CSF post-transplant. The granulocytes were started on the anticipated day of neutropenia after conditioning and graft infusion and continued until evidence of graft recovery. Volunteer community donors underwent mobilization with dexamethasone 8 mg PO plus G-CSF 480 mcg SC, followed the next day by a 7-liter leukapheresis procedure (Spectra) using Tricitrasol/Hetastarch (Hespan) as the anticoagulant/sedimenting solution. Patients received a mean of 4.5 transfusions each, with three patients receiving biweekly transfusions and one receiving transfusions three times a week. The mean number of granulocytes per component transfused was 6.17 × 10e10 (range 4.0–9.12). This resulted in a mean of 2.78 × 10e9 granulocytes transfused per kg recipient weight (range 0.76–4.48). All patients tolerated the infusions well, without respiratory symptoms. The mean increase in absolute neutrophil count posttransfusion was 1.95 × 10e3/uL (range 0.5–4.61), although the timing of collection of the blood count samples was variable for each transfusion. Using a dihydrorhodamine (DHR) fluorescence based assay we were able to track the presence of oxidase positive cells to help differentiate transfused donor from residual host cells. DHR assays were performed before and after every transfusion in one patient. The number of DHR positive cells prior to infusion was 0–1.4% with a rise to 68.2% 24 hours after transfusion. 24.5% oxidase positive cells were still detectable almost 72 hours after transfusion, just prior to the next transfusion. One product required sedimentation for ABO incompatibility. The mean time to engraftment was 22 days and did not differ in patients with CGD receiving the same transplant regimen with (n=4) or without (n=6) peri-transplant granulocyte transfusions (30 days). Although all four patients had infectious processes not responding to standard antimicrobial therapy prior to transplant, there was no evidence of progressive infection during the period of neutropenia. Imaging studies of the brain, lung and/or spine suggested improvement in the infectious process in all four patients, although the timing of the scans made assessments inconclusive. Our prior experience with granulocyte transfusions in patients with CGD not undergoing transplant is that the cells do not persist in the circulation longer than 24 hours. Higher cell doses per kg in our four patients may have contributed to the sustained detection of transfused circulating cells, particularly as three of the patients weighed less than 21 kg. Peri-transplant immune suppression may also have facilitated the longer circulation time of the cells. We conclude that community-donor granulocyte transfusions are well tolerated in non-alloimmunized CGD patients undergoing HSCT, do not impact engraftment, are logistically feasible, and may provide a therapeutic bridge for patients with an underlying infection during a prescribed period of neutropenia, thus decreasing transplantation risk for such patients.
Disclosures:
No relevant conflicts of interest to declare.
915. Insertional Analyses in Rhesus Monkey Blood Cells after Non-Myeloablative Hematopoietic Stem Cell Marking with a Therapeutic Onco-Retroviral Vector for X-Linked Chronic Granulomatous Disease
