Kimberly A. Kasow

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.

Human CD4+CD25+ Regulatory T Cells Share Equally Complex and Comparable Repertoires with CD4+CD25− Counterparts

CD4+CD25+ T cells are critical mediators of peripheral immune tolerance. However, many developmental and functional characteristics of these cells are unknown, and knowledge of human regulatory T cells is particularly limited. To better understand how human CD4+CD25+ T cells develop and function, we examined the diversity of CD4+CD25+ and CD4+CD25− T cell repertoires in both thymus and peripheral blood. Levels of T receptor excision circles (TREC) were comparable in purified CD4+CD25+ and CD4+CD25− thymic populations, but were significantly higher than those in samples derived from peripheral blood, consistent with murine studies demonstrating thymic development of CD4+CD25+ regulatory T cells. Surprisingly, CD4+CD25− T cells isolated from peripheral blood had greater TREC quantities than their CD4+CD25+ counterparts, supporting the possibility of extrathymic expansion as well. CD4+CD25+ and CD4+CD25− T cells from a given individual showed overlapping profiles with respect to diversity by Vβ staining and spectratyping. Interestingly, CD4+CD25+ T cells have lower quantities of CD3 than CD4+CD25− T cells. Collectively, these data suggest that human CD4+CD25+ T cells recognize a similar array of Ags as CD4+CD25− T cells. However, reduced levels of TCR on regulatory T cells suggest different requirements for activation and may contribute to how the immune system regulates whether a particular response is suppressed or augmented.

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.

Amifostine Protects Against Cisplatin-Induced Ototoxicity in Children With Average-Risk Medulloblastoma

PURPOSE To determine the role of amifostine as a protectant against cisplatin-induced ototoxicity in patients with average-risk (AR) medulloblastoma treated with craniospinal radiotherapy and four cycles of cisplatin-based, dose-intense chemotherapy and stem-cell rescue. PATIENTS AND METHODS The primary objective was to determine whether, in patients with AR medulloblastoma (n = 62), amifostine would decrease the need for hearing aids (defined as >or= grade 3 ototoxicity in one ear) compared with a control group (n = 35), 1 year from initiating treatment. Ninety-seven patients received craniospinal irradiation (23.4 Gy) followed by 55.8 Gy to the primary tumor bed using three-dimensional conformal technique, and four cycles of high-dose cyclophosphamide (4,000 mg/m(2)/cycle), cisplatin (75 mg/m(2)/cycle), and vincristine (two 1.5 mg/m(2) doses/cycle) and stem-cell rescue. When used, amifostine (600 mg/m(2)/dose) was administered as a bolus immediately before and 3 hours into the cisplatin infusion. RESULTS The median age of the 97 patients was 8.7 years (range, 3.2 to 20.2 years). The study and control groups were similar in age and sex distribution. Amifostine was well-tolerated. One year after treatment initiation, 13 patients (37.1%) in the control group versus nine (14.5%; one-sided chi(2) test P = .005) of the amifostine-treated patients had at least grade 3 ototoxicity, requiring hearing aid in at least one ear. CONCLUSION Amifostine administered before and during the cisplatin infusion can significantly reduce the risk of severe ototoxicity in patients with AR medulloblastoma receiving dose-intense chemotherapy.

Outcomes of pediatric bone marrow transplantation for leukemia and myelodysplasia using matched sibling, mismatched related, or matched unrelated donors

Although some trials have allowed matched or single human leukocyte antigen (HLA)-mismatched related donors (mmRDs) along with HLA-matched sibling donors (MSDs) for pediatric bone marrow transplantation in early-stage hematologic malignancies, whether mmRD grafts lead to similar outcomes is not known. We compared patients < 18 years old reported to the Center for International Blood and Marrow Transplant Research with acute myeloid leukemia, acute lymphoblastic leukemia, chronic myeloid leukemia, and myelodysplastic syndrome undergoing allogeneic T-replete, myeloablative bone marrow transplantation between 1993 and 2006. In total, patients receiving bone marrow from 1208 MSDs, 266 8/8 allelic-matched unrelated donors (URDs), and 151 0-1 HLA-antigen mmRDs were studied. Multivariate analysis showed that recipients of MSD transplants had less transplantation-related mortality, acute graft-versus-host disease (GVHD), and chronic GVHD, along with better disease-free and overall survival than the URD and mmRD groups. No differences were observed in transplant-related mortality, acute and chronic GVHD, relapse, disease-free survival, or overall survival between the mmRD and URD groups. These data show that mmRD and 8/8 URD outcomes are similar, whereas MSD outcomes are superior to the other 2 sources. Whether allele level typing could identify mmRD recipients with better outcomes will not be known unless centers alter practice and type mmRD at the allele level.

A prospective cohort study of late sequelae of pediatric allogeneic hematopoietic stem cell transplantation.

As survivors of pediatric allogeneic hematopoietic stem cell transplantations (HSCTs) increase in number, it is increasingly important to evaluate their well-being. We conducted this prospective cohort study to evaluate the cumulative incidence and risk factors for late sequelae of HSCT. Comprehensive surveillance tests were performed annually on every participant, regardless of signs and symptoms, to obtain accurate information on the time-of-onset of each late event to allow hazard function analyses. All participants included in this report had been followed for at least 3 years after HSCT. With a median follow-up of 9 years and a current age of 18.5 years, only 20 of the 155 participants (13%) had no late sequelae; 18 survivors (12%) had 1 chronic health condition, 71 (46%) had 2-4 conditions, and 46 (30%) had 5-9 conditions. Risk factors for increasing number of chronic conditions included young age at the time of HSCT, female sex, high radiation dose, and history of chronic graft-versus-host disease. The cumulative incidence at 10 years for common late events was as follows (ordered by the median time-of-onset): osteonecrosis 13.8%, chronic renal insufficiency 26.8%, hypothyroidism 45.1%, growth hormone deficiency 31.2%, female hypogonadism 57.4%, osteopenia 47.7%, cataracts 43.4%, pulmonary dysfunction 63.2%, and male hypogonadism 20.3%. Coexistence of multiple late sequelae was common in HSCT survivors. Our findings provide a basis for more effective patient counseling, optimal surveillance, and early intervention. Abbreviations: ACTH = adrenocorticotropin, CI = confidence intervals, DLCO = diffusing capacity of carbon monoxide, FEV1 = forced expiratory volume in 1 second, FSH = follicle-stimulating hormone, FT4 = free thyroxine, FVC = forced vital capacity, GVHD = graft-versus-host disease, HSCTs = hematopoietic stem cell transplantations, IGFBP3 = insulin-like growth factor binding protein-3, LH = luteinizing hormone, OR = odds ratio, PFT = pulmonary function test, TBI = total body irradiation, TLC = total lung capacity, TSH = thyroid stimulating hormone.

A pilot study of risk-adapted radiotherapy and chemotherapy in patients with supratentorial PNET

We undertook this study to estimate the event-free survival (EFS) of patients with newly diagnosed supratentorial primitive neuroectodermal tumor (SPNET) treated with risk-adapted craniospinal irradiation (CSI) with additional radiation to the primary tumor site and subsequent high-dose chemotherapy supported by stem cell rescue. Between 1996 and 2003, 16 patients with SPNET were enrolled. High-risk (HR) disease was differentiated from average-risk (AR) disease by the presence of residual tumor (M(0) and tumor size > 1.5 cm(2)) or disseminated disease in the neuraxis (M(1)-M(3)). Patients received risk-adapted CSI: those with AR disease received 23.4 Gy; those with HR disease, 36-39.6 Gy. The tumor bed received a total of 55.8 Gy. Subsequently, all patients received four cycles of high-dose cyclophosphamide, cisplatin, and vincristine with stem cell support. The median age at diagnosis was 7.9 years; eight patients were female. Seven patients had pineal PNET. Twelve patients are alive at a median follow-up of 5.4 years. The 5-year EFS and overall survival (OS) estimates for all patients were 68% +/- 14% and 73% +/- 13%. The 5-year EFS and OS estimates were 75% +/- 17% and 88% +/- 13%, respectively, for the eight patients with AR disease and 60% +/- 19% and 58% +/- 19%, respectively, for the eight with HR disease. No deaths were due to toxicity. High-dose cyclophosphamide-based chemotherapy with stem cell support after risk-adapted CSI results in excellent EFS estimates for patients with newly diagnosed AR SPNET. Further, this chemotherapy allows for a reduction in the dose of CSI used to treat AR SPNET without compromising EFS.

Successful Matched Sibling Donor Marrow Transplantation Following Reduced Intensity Conditioning in Children with Hemoglobinopathies

Fifty‐two children with symptomatic sickle cell disease sickle cell disease (SCD) (N = 43) or transfusion‐dependent thalassemia (N = 9) received matched sibling donor marrow (46), marrow and cord product (5), or cord blood (1) allografts following reduced intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan between March 2003 and May 2014*. The Kaplan–Meier probabilities of overall and event‐free survival at a median of 3.42 (range, 0.75–11.83) years were 94.2% and 92.3% for the group, 93% and 90.7% for SCD, and 100% and 100% for thalassemia, respectively. Treatment‐related mortality (all related to graft versus host disease, GVHD) was noted in three (5.7%) recipients, all 17–18 years of age. Acute and chronic GVHD was noted in 23% and 13%, respectively, with 81% of recipients off immunosuppression by 1 year. Graft rejection was limited to the single umbilical cord blood recipient who had prompt autologous hematopoietic recovery. Fourteen (27%) had mixed chimerism at 1 year and beyond; all had discontinued immunosuppression between 4 and 12 months from transplant with no subsequent consequence on GVHD or rejection. Infectious complications included predominantly bacteremia (48% were staphylococcus) and CMV reactivation (43%) necessitating preemptive therapy. Lymphocyte recovery beyond 6 months was associated with subsidence of infectious complications. All patients who engrafted were transfusion independent; no strokes or pulmonary complications of SCD were noted, and pain symptoms subsided within 6 months posttransplant. These findings support using RIC for patients with hemoglobinopathy undergoing matched sibling marrow transplantation (*www.Clinical Trials.gov: NCT00920972, NCT01050855, NCT02435901). Am. J. Hematol. 90:1093–1098, 2015.

Secondary solid cancer screening following hematopoietic cell transplantation.

Hematopoietic stem cell transplant (HCT) recipients have a substantial risk of developing secondary solid cancers, particularly beyond 5 years after HCT and without reaching a plateau overtime. A working group was established through the Center for International Blood and Marrow Transplant Research and the European Group for Blood and Marrow Transplantation with the goal to facilitate implementation of cancer screening appropriate to HCT recipients. The working group reviewed guidelines and methods for cancer screening applicable to the general population and reviewed the incidence and risk factors for secondary cancers after HCT. A consensus approach was used to establish recommendations for individual secondary cancers. The most common sites include oral cavity, skin, breast and thyroid. Risks of cancers are increased after HCT compared with the general population in skin, thyroid, oral cavity, esophagus, liver, nervous system, bone and connective tissues. Myeloablative TBI, young age at HCT, chronic GVHD and prolonged immunosuppressive treatment beyond 24 months were well-documented risk factors for many types of secondary cancers. All HCT recipients should be advised of the risks of secondary cancers annually and encouraged to undergo recommended screening based on their predisposition. Here we propose guidelines to help clinicians in providing screening and preventive care for secondary cancers among HCT recipients.

1α,25-dihydroxyvitamin D3 (vitamin D3) catalyzes suppressive activity on human natural regulatory T cells, uniquely modulates cell cycle progression, and augments FOXP3

Human natural regulatory T cells (nTregs) show great promise for therapeutically modulating immune-mediated disease, but remain poorly understood. One explanation under intense scrutiny is how to induce suppressive function in non-nTregs and increase the size of the regulatory population. A second possibility would be to make existing nTregs more effective, like a catalyst raises the specific activity of an enzyme. The latter has been difficult to investigate due to the lack of a robust short-term suppression assay. Using a microassay described herein we demonstrate that nTregs in distinct phases of cell cycle progression exhibit graded degrees of potency. Moreover, we show that physiological concentrations of 1α,25-dihydroxyvitamin D3 (vitamin D3) boosts nTregs function. The enhanced suppressive capacity is likely due to vitamin D3s ability to uniquely modulate cell cycle progression and elevate FOXP3 expression. These data suggest a role for vitamin D3 as a mechanism for catalyzing potency of nTregs.