c-CBL (CBL) encodes a member of the Cbl family of proteins, which functions as an E3 ubiquitin ligase. We describe a dominant developmental disorder resulting from germline missense CBL mutations, which is characterized by constitutional anomalies that include impaired growth, developmental delay, cryptorchidism, and a predisposition to juvenile myelomonocytic leukemia (JMML). Some individuals experienced spontaneous regression of their JMML but developed vasculitis later in life. Importantly, JMML specimens from affected children show loss of the normal CBL allele through acquired isodisomy. Consistent with these genetic data, the common p.Y371H mutant Cbl protein induces cytokine-independent growth and constitutive phosphorylation of ERK, AKT, and S6 only in hematopoietic cells in which normal Cbl expression is reduced by RNA interference. We conclude that germline CBL mutations have developmental, tumorigenic, and functional consequences that are reminiscent of disorders that are caused by hyperactive Ras/Raf/MEK/ERK signaling and include neurofibromatosis type 1, and Noonan, Costello, cardiofaciocutaneous, and Legius syndromes.

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Infections continue to be a significant cause of morbidity in cardiac surgery patients. Knowledge of risk factors for infection could be useful in preventive and treatment strategies for these high-risk groups.

BK virus is a significant cause of hemorrhagic cystitis after hematopoietic stem cell transplantation (HSCT). However, its role in nephropathy post-HSCT is less studied. We retrospectively evaluated clinical outcomes in pediatric HSCT patients with hemorrhagic cystitis. Although most of these patients had very high urine BK viral loads (viruria), patients with higher BK plasma loads (viremia) had significant renal dysfunction, a worse clinical course, and decreased survival. Patients with a peak plasma BK viral load of >10,000 copies/mL (high viremia) were more likely to need dialysis and aggressive treatment for hemorrhagic cystitis compared to patients with ≤ 10,000 copies/mL (low viremia). Conversely, most patients with low viremia had only transient elevations in creatinine, and less severe hemorrhagic cystitis that resolved with supportive therapy. Overall survival (OS) at 1 year post-HSCT was 89% in the low viremia group and 48% in the high viremia group. We conclude that the degree of BK viremia, and not viruria, may predict renal, urologic, and overall outcome in the post-HSCT population.

• Alemtuzumab levels impact acute GVHD, mixed chimerism, and lymphocyte recovery after alemtuzumab, fludarabine, and melphalan RIC HCT.• An in vivo lytic threshold appears to lie near 0.1 to 0.16 mg/mL; targeted dose trials are warranted to optimize outcomes.Reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) with alemtuzumab, fludarabine, and melphalan is an effective approach for patients with nonmalignant disorders. Mixed chimerism and graft-versus-host-disease (GVHD) remain limitations on success. We hypothesized that higher levels of alemtuzumab at day 0 would result in a low risk of acute GVHD, a higher risk of mixed chimerism, and delayed early lymphocyte recovery and that alemtuzumab level thresholds for increased risks of these outcomes would be definable. We collected data from 105 patients to examine the influence of peritransplant alemtuzumab levels on acute GVHD, mixed chimerism, and lymphocyte recovery. The cumulative incidences of initial grades I-IV, II-IV, and III-IV acute GVHD in patients with alemtuzumab levels £0.15 vs ‡0.16 mg/mL were 68% vs 18% (P < .0001), 47% vs 13% (P 5 .0002), and 32% vs 8%, respectively (P 5 .005). The cumulative incidence of mixed chimerism in patients with an alemtuzumab level £0.15 mg/mL was 21%, vs 42% with levels of 0.16 to 4.35 mg/mL, and 100% with levels >4.35 mg/mL (P 5 .003). Patients with alemtuzumab levels £0.15 or 0.16 to 0.56 mg/mL had higher lymphocyte counts at day 130 and higher T-cell counts at day 1100 compared with patients with levels ‡0.57 mg/mL (all P < .05). We conclude that peritransplant alemtuzumab levels impact acute GVHD, mixed chimerism, and lymphocyte recovery following RIC HCT with alemtuzumab, fludarabine, and melphalan. Precision dosing trials are warranted. We recommend a day 0 therapeutic range of 0.2 to 0.4 mg/mL. (Blood.

Reduced-intensity conditioning (RIC) improves the outcomes of hematopoietic cell transplantation (HCT) in patients with hemophagocytic lymphohistiocytosis (HLH). Proximal (ie, close to graft infusion) dosing of alemtuzumab is associated with a high incidence of mixed chimerism, whereas distal (ie, distant from graft infusion) dosing is associated with less mixed chimerism but more acute graft-versus-host disease (GVHD). The alemtuzumab dose per kilogram of body weight also influences these outcomes. We hypothesized that an intermediate alemtuzumab dosing schedule would reduce mixed chimerism and maintain a low incidence of acute GVHD. In this study, 24 consecutive HCTs were performed in patients with HLH or a related disorder using a novel intermediate alemtuzumab schedule of 1 mg/kg starting on day -14. The cumulative incidences (CIs) of mixed chimerism, upfront acute GVHD grades II-IV, and receipt of additional hematopoietic cell products after HCT were compared in patients treated with a distal alemtuzumab schedule (n = 15) and those treated with a proximal alemtuzumab schedule (n = 33). All patients received fludarabine and melphalan. The CI of mixed chimerism was 31% in the intermediate group, 72% in the proximal group (P < .01), and 75% in the distal group patients who received ≥2 mg/kg alemtuzumab (P = .03). The CI of acute GVHD grades II-IV before the development of mixed chimerism was 4% in the intermediate group, 0% in the proximal group, and 13% in the distal group (P = .04, proximal versus distal). The 1-year CI of administration of additional hematopoietic cell products for mixed chimerism (donor lymphocyte infusion ± hematopoietic stem cell boost ± repeat HCT) was 14% in the intermediate group, 53% in the proximal group (P = .01), and 38% in the distal ≥2 mg/kg alemtuzumab group (P = .02). Our findings indicate that intermediate RIC reduces the incidence of mixed chimerism, is associated with a low incidence of upfront acute GVHD, and decreases the need for additional hematopoietic cell products after HCT.

• Alternative donor HCT can be performed in patients with FA without using radiation.• All 26 patients younger than 10 years of age undergoing HCT for marrow failure using lower-dose busulfancontaining regimen survived.Fanconi anemia (FA) is an inherited bone marrow failure syndrome characterized by chromosomal fragility, progressive marrow failure, and cancer predisposition. Hematopoietic cell transplantation (HCT) is curative for FA-related marrow failure or leukemia, but both radiation exposure during transplant and graft-versus-host disease (GVHD) may increase risk of later malignancies of the head and neck and anogenital area. In this study, we tested a radiation-free conditioning regimen with a T-cell-depleted graft to eliminate radiation exposure and minimize early and late toxicities of transplant. Forty-five patients (median age, 8.2 years; range 4.3-44) with FA underwent HCT between June 2009 and May 2014. The preparative regimen included busulfan, cyclophosphamide, fludarabine, and rabbit anti-thymocyte globulin. Busulfan levels were monitored to avoid excess toxicity. All grafts were CD34-selected/T-cell-depleted using the CliniMacs CD34 columns (Miltenyi). Thirty-four patients (75.6%) with marrow failure and 11 (24.4%) with myelodysplastic syndrome underwent HCT using matched unrelated (n 5 25, 55.5%), mismatched unrelated (n 5 14, 31.1%), or mismatched related donors (n 5 6, 13.4%). One year probabilities of overall and disease-free survival for the entire cohort, including patients with myeloid malignancy and those receiving mismatched related/haploidentical grafts, were 80% (66%) and 77.7% (66.2%), respectively (median follow-up 41 months). All young children (<10 years of age) undergoing HCT for marrow failure using low-dose busulfancontaining regimen survived. No patients developed acute grade 3-4 GVHD. Sequential reduction of busulfan dose was successfully achieved per study design. Our results show excellent outcomes in patients with FA undergoing alternative donor HCT without radiation exposure. The study is registered to www.clinicaltrials.gov as #NCT01082133. (Blood. 2017;129(16):2308-2315

Alemtuzumab, fludarabine, and melphalan reduced-intensity conditioning (RIC) regimens are increasingly used for the hematopoietic cell transplantation (HCT) of pediatric and young adult patients with nonmalignant diseases. Early experience suggests that these regimens are associated with good survival but a high incidence of mixed chimerism, which we have previously shown to be influenced by the alemtuzumab schedule. We hypothesized that the underlying diagnosis and donor graft source would also affect the development of mixed chimerism and that the majority of patients would survive RIC HCT without graft loss. To examine this, we conducted a retrospective study of 206 patients with metabolic diseases, non-Fanconi anemia marrow failure disorders, and primary immune deficiencies who underwent 210 consecutive RIC HCT procedures at Cincinnati Children’s Hospital. Ninety-seven percent of the patients engrafted. Mixed donor and recipient chimerism developed in 46% of patients. Patients with marrow failure had a low risk of mixed chimerism (hazard ratio [HR], .208; 95% confidence interval [CI], .061 to .709; P = .012). The risk of mixed chimerism was high in patients who received a cord blood graft (HR, 3.122; 95% CI, 1.236 to 7.888; P = .016). As expected, patients who received a proximal or higher dose per kilogram of alemtuzumab schedule also experienced higher rates of mixed chimerism (all HR > 2, all P < .05). At the time of last follow-up (median, 654 days; range, 13 to 3337), over 75% of patients had greater than 90% whole blood donor chimerism. A second transplantation was performed in 5% of patients. Three-year survival without retransplantation was 84% (95% CI, 71% to 98%) for patients who underwent transplantation with an HLA-matched sibling donor. Survival without retransplantation was negatively affected by lack of a matched related donor, increasing age, and development of grades III and IV acute graft-versus-host disease. We conclude that alemtuzumab, fludarabine, and melphalan RIC HCT offers good results for many patients and that the risk of developing mixed chimerism is influenced by underlying diagnosis, graft source, and alemtuzumab dosing.