Paul Woodard

Cidofovir for the treatment of adenoviral infection in pediatric hematopoietic stem cell transplant patients

Background. Adenovirus (ADV) infections are associated with significant morbidity and mortality after hematopoietic stem cell transplantation (HSCT). The virus is endemic in the general pediatric population and frequently causes severe disease in immunocompromised patients, especially children. We report our experience with cidofovir (CDV) for treatment of ADV infection in 57 HSCT patients, median age 8 years (range 0.5–26). Methods. Peripheral blood was prospectively screened weekly on all patients for ADV by quantitative real-time PCR for the first 100 days post-HSCT or longer if clinically indicated. Cultures for viral pathogens were performed from other involved sites. Upon detection of ADV by PCR, culture or tissue histopathology, CDV was given intravenously at 5 mg/kg weekly for 2 consecutive weeks, then every 2 weeks until 3 consecutive ADV-negative samples were documented from all previously invoved sites. Results. The clinical manifestations of ADV infection were: diarrhea (53%), fever (21%), hemorrhagic cystitis (12%), and pneumonitis (11%). Eight patients (14%) presented with disseminated disease. CDV treatment resulted in complete resolution of clinical symptoms in 56 (98%) patients in whom the virus became undetectable by all methods. One patient died due to ADV pneumonitis. No cases of dose-limiting nephrotoxicity were observed. Conclusions. Cidofovir appeared safe and effective for the treatment of ADV infection in this predominantly pediatric HSCT population. Vigilant surveillance and early treatment with CDV can prevent the poor outcomes associated with ADV disease. A larger prospective study is needed to further determine the role of CDV in the treatment of ADV after HSCT.

T‐cell alloreactivity dominates natural killer cell alloreactivity in minimally T‐cell‐depleted HLA‐non‐identical paediatric bone marrow transplantation

Summary. Natural killer (NK) cell alloreactivity resulting from killer immunoglobulin‐like receptor (KIR) ligand incompatibility improves outcomes in patients receiving extensively T‐cell‐depleted bone marrow (BM) grafts. Patients with KIR ligand incompatibility are at risk for donor T‐cell alloreactivity. We investigated the relative significance of NK‐cell and T‐cell alloreactivity in 105 paediatric patients who received a minimally T‐cell‐depleted human leucocyte antigen‐non‐identical BM transplantation. Donor NK‐cell incompatibility did not improve patient outcome [engraftment, graft‐versus‐host disease (GVHD), relapse or overall survival]. In contrast, donor T‐cell incompatibility was a risk factor for acute GVHD, chronic GVHD and death. Thus, T‐cell alloreactivity dominated that of NK cells in minimally T‐cell‐depleted grafts.

Rapid immune reconstitution after a reduced‐intensity conditioning regimen and a CD3‐depleted haploidentical stem cell graft for paediatric refractory haematological malignancies

The main obstacles to successful haploidentical haematopoietic stem cell transplantation from a mismatched family member donor are delayed immune reconstitution, vulnerability to infections and severe graft‐versus‐host disease (GvHD). We designed a reduced‐intensity conditioning regimen that excluded total body irradiation and anti‐thymocyte globulin in order to expedite immune reconstitution after a CD3‐depleted haploidentical stem cell transplant. This protocol was used to treat 22 paediatric patients with refractory haematological malignancies. After transplantation, 91% of the patients achieved full donor chimaerism. They also showed rapid recovery of CD3+ T‐cells, T‐cell receptor (TCR) excision circle counts, TCRβ repertoire diversity and natural killer (NK)‐cells during the first 4 months post‐transplantation, compared with those results from a group of patients treated with a myeloablative conditioning regimen. The incidence and extent of viremia were limited and no lethal infection was seen. Only 9% of patients had grade 3 acute GvHD, while 27% patients had grade 1 and another 27% had grade 2 acute GvHD. This well‐tolerated regimen appears to accelerate immune recovery and shorten the duration of early post‐transplant immunodeficiency, thereby reducing susceptibility to viral infections. Rapid T‐cell reconstitution, retention of NK‐cells in the graft and induction of low grade GvHD may also enhance the potential anti‐cancer immune effect.

Changes in outcomes (1996-2004) for pediatric oncology and hematopoietic stem cell transplant patients requiring invasive mechanical ventilation

Objective: To assess the following hypotheses regarding mechanically ventilated pediatric oncology patients, including those receiving hematopoietic stem cell transplant (HSCT) and those not receiving HSCT: 1) outcomes are more favorable for nontransplant oncology patients than for those requiring HSCT; 2) outcomes have improved for both populations over time; and 3) there are factors available during the time of mechanical ventilation that identify patients with a higher likelihood of dying. Design: Retrospective review. Setting: Free-standing, tertiary care, pediatric hematology oncology hospital. Patients: All patients requiring invasive mechanical ventilation with a diagnosis of cancer or following HSCT from January 1996 to December 2004. Interventions: Bivariate and multivariate analysis. Dates of admission were grouped into time periods for analysis: 1996–1998, 1999–2001, and 2002–2004. Measurements and Main Results: There were 401 courses of mechanical ventilation (329 patients) analyzed. Forty-five percent of HSCT admissions (92 of 206) vs. 75% of non-HSCT oncology admissions (146 of 195) were extubated and discharged from the pediatric intensive care unit (p < .0001). Twenty-five percent of HSCT vs. 60% of non-HSCT admissions survived 6 months (p < .0001). Among admissions with an abnormal chest radiograph and a Pao2/Fio2 ratio <200, pediatric intensive care unit survival increased for each successive time period, with 45% of HSCT and 83% of non-HSCT admissions surviving during 2002–2004. In multivariate analysis of all study patients, Pediatric Risk of Mortality scores on the day of intubation, allogeneic HSCT, cardiovascular failure, hepatic failure, neurologic failure, a previous course of mechanical ventilation within 6 months, and the time period intubated were associated with mortality. With the exception of time period, these same variables were associated with mortality in multivariate analysis of only HSCT patients. Conclusions: HSCT patients who require mechanical ventilation have worse outcomes than non-HSCT oncology patients. Outcomes for both groups have improved over time. Allogeneic transplant, higher Pediatric Risk of Mortality scores, need for repeated mechanical ventilation, and concomitant organ system dysfunction are risk factors for death.

Hemorrhagic Cystitis after Allogeneic Bone Marrow Transplantation in Children: Clinical Characteristics and Outcome

Hemorrhagic cystitis (HC) is a well-documented adverse event experienced by patients undergoing hematopoietic stem cell transplantation. When severe, HC causes significant morbidity, leads to renal complications, prolongs hospitalization, increases health-care costs, and occasionally contributes to death. We retrospectively studied the medical records of 245 children undergoing an initial allogeneic bone marrow transplantation for malignant disease at St. Jude Childrens Research Hospital between 1992 and 1999 to describe the clinical course of HC in all patients and to identify the risk factors for HC in this cohort. Conditioning regimens included cyclophosphamide, cytarabine, and total body irradiation. Grafts from unrelated or mismatched related donors were depleted of T lymphocytes, whereas matched sibling grafts were unmanipulated. All patients received cyclosporine as prophylaxis for graft-versus-host disease. Recipients of grafts from matched siblings also received pentoxifylline or short-course methotrexate. Severe HC developed in 27 patients (11.0%). The median duration of HC was 73 days (range, 5-619 days); 12 patients had ongoing HC at the time of death. In univariate analyses, patients were at increased risk of severe HC if they were male (P =.021) or had received T cell-depleted grafts (P =.017), grafts from unrelated donors (P =.021), a lower total nucleated cell dose (P =.032), or antithymocyte globulin (P =.0446). Multiple regression analysis revealed male sex (beta =.97; P =.027) and unrelated donor graft recipients (beta =.83; P =.039) to be significant factors.

Brain parenchymal damage after haematopoietic stem cell transplantation for severe sickle cell disease

Prospective magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), neuropsychological testing and neurological examinations were performed to determine the long‐term effect of successful haematopoietic stem cell transplantation on the neurological status of nine children with sickle cell disease. A scoring system for severity of brain parenchymal and vascular lesions was developed and applied. Neurological examinations and neuropsychometric tests were stable, but MRI and MRA studies were not. Transient changes occurred early in two patients. Persistent changes occurred in five. Parenchymal lesions occurred in zero of two patients without prior lacunae or infarcts and in all seven with prior lacunae or infarcts (P = 0·0278).

Outcome of hematopoietic stem cell transplantation for pediatric patients with therapy‐related acute myeloid leukemia or myelodysplastic syndrome

Therapy‐related myelodysplastic syndrome (t‐MDS) and acute myeloid leukemia (t‐AML) carry a poor prognosis. We analyzed the results of allogeneic HSCT in 38 children to determine which factors, if any, affected outcome.

Pulmonary Nodular Lesions in Bone Marrow Transplant Recipients Impact of Histologic Diagnosis on Patient Management and Prognosis

Bone marrow transplantation is associated with numerous pulmonary complications, which may manifest as nodules. We studied 33 bone marrow transplant (BMT) recipients in whom pulmonary nodular lesions (PNLs) developed during a 5-year period and who underwent open lung biopsy (OLB) for diagnosis. Of 33 patients with PNL, 15 (45%) had pulmonary cytolytic thrombi (PCT), a recently described condition characterized histologically by occlusive vascular lesions and hemorrhagic infarcts and clinically by a favorable outcome. Clinical symptoms and radiologic abnormalities disappeared during a period of a few weeks. None of the patients died of PCT; 10 were alive at last contact. The second most common cause of PNL (8/33 [24%]) was Aspergillus infection, which was the cause of death in 6. OLB is an effective way of obtaining diagnostic tissue in BMT recipients with PNLs. Histologic examination is accurate in determining the cause of PNLs and identifying lesions that have a favorable outcome and those that require a change in treatment.

Effective donor lymphohematopoietic reconstitution after haploidentical CD34+ -selected hematopoietic stem cell transplantation in children with refractory severe aplastic anemia

Summary:Peritransplant toxicity and a delay in effective immune reconstitution have limited the utility of alternate donor transplantation for children with refractory severe aplastic anemia. We have assessed the effectiveness of infusing large numbers of highly purified haploidentical CD34+ cells after immunoablative conditioning in three patients who had failed intensive immunosuppression, lacked unrelated donors, and had active or recent serious infections. One patient rejected the first infusion, but engrafted after a second infusion from the same donor. This patient died 4 months after hematopoietic stem cell transplantation with no evidence of lymphoid reconstitution. Two patients experienced mixed chimerism requiring treatment with antibodies and/or donor lymphocyte infusion. Both currently survive more than 1 year after transplantation with normal blood counts, 100% donor engraftment, effective lymphoid reconstitution, and no chronic graft-versus-host disease. We observed functional thymopoiesis as measured by lymphocyte immunophenotyping, T cell receptor excision circles and T cell receptor Vβ spectratyping complexity analysis. Further study is required to validate the initial promise of these preliminary observations.

Effect of HLA class I or class II incompatibility in pediatric marrow transplantation from unrelated and related donors

The degree of histoincompatibility that can be tolerated, and the relative importance of matching at individual HLA class I and class II locus in bone marrow transplantation (BMT) has not been established. We hypothesized that matching for HLA-DR may not be more important than matching for HLA-A or HLA-B in selection of a donor for successful BMT. We retrospectively analyzed the outcomes of 248 consecutive pediatric patients who received allogeneic BMT from related donors (RD, n = 119) or unrelated donors (URD, n = 129). HLA-A and HLA-B were serologically matched, and HLA-DRB1 were identical by DNA typing in 69% of donor-recipient pairs. Most patients (89%) had hematologic malignancies; the rest had aplastic anemia or a congenital disorder. One HLA-A antigen mismatch was associated with a decrease in survival (p = 0.003) and a delay in granulocyte engraftment (p = 0.02) in recipients of RD marrow; as well as a decrease in survival (p = 0.02) and the development of severe acute graft-versus-host disease (GVHD) (p = 0.03) in recipients of URD marrow. One HLA-B antigen mismatch was associated with a decrease in the survival (p = 0.05) and the development of severe GVHD (p = 0.0007) in recipients of RD marrow. One HLA-DRB1 allele mismatch was associated only with a decrease in the survival (p = 0.0003) of recipients of RD marrow. Results of this study suggest that disparity in HLA-A and HLA-B antigens may not be better tolerated than disparity in HLA-DR allele in allogeneic BMT. Further studies are warranted to confirm our results.