A prospective multi-institutional study of eculizumab to treat high-risk stem cell transplantation-associated TMA.

ABSTRACT: High-risk, complement mediated, untreated transplant-associated thrombotic microangiopathy (hrTMA) has dismal outcomes due to multi-organ dysfunction syndrome (MODS). The complement C5 blocker eculizumab shows promising results in hrTMA, but has not been prospectively studied in hematopoietic stem cell transplant (HCT) recipients. We performed the first multi-institutional prospective study in children and young adults to evaluate eculizumab as an early targeted intervention for hrTMA/MODS. We hypothesized that eculizumab would more than double survival in HCT recipients with hrTMA, compared to our prior study of prospectively screened, untreated hrTMAs serving as historical controls. HrTMA features (elevated terminal complement (sC5b-9) and proteinuria measured by random urine protein/creatinine ratio (≥1mg/mg)) were required for inclusion. The primary endpoint was survival at 6 six-months from hrTMA diagnosis. Secondary endpoints were cumulative incidence of MODS 6 months after hrTMA diagnosis and 1-year posttransplant survival. Eculizumab dosing included intensive loading, induction, and maintenance phases for up to 24 weeks of therapy. All 21 evaluated study subjects had MODS. Primary and secondary study endpoints were met by demonstrating survival of 71% (P < .0001) 6 months after hrTMA diagnosis and 62% 1 year after transplant. Of fifteen survivors, 11 (73%) fully recovered organ function and are well. Our study demonstrates significant improvement in survival and recovery of organ function in hrTMA using an intensified eculizumab dosing and real time biomarker monitoring. This study serves as a benchmark for planning future studies that should focus on preventative measures or targeted therapy to be initiated prior to organ injury. This trial was registered at www.clinicaltrials.gov as #NCT03518203.

A randomized phase 2 trial of oral vitamin A for graft-versus-host disease in children and young adults.

ABSTRACT: Vitamin A plays a key role in the maintenance of gastrointestinal homeostasis and promotes a tolerogenic phenotype in tissue resident macrophages. We conducted a prospective randomized double-blinded placebo-controlled clinical trial in which 80 recipients of hematopoietic stem cell transplantation (HSCT) were randomized 1:1 to receive pretransplant high-dose vitamin A or placebo. A single oral dose of vitamin A of 4000 IU/kg, maximum 250 000 IU was given before conditioning. The primary end point was incidence of acute graft-versus-host disease (GVHD) at day +100. In an intent-to-treat analysis, incidence of acute GVHD was 12.5% in the vitamin A arm and 20% in the placebo arm (P = .5). Incidence of acute gastrointestinal (GI) GVHD was 2.5% in the vitamin A arm (P = .09) and 12.5% in the placebo arm at day +180. Incidence of chronic GVHD was 5% in the vitamin A arm and 15% in the placebo arm (P = .02) at 1 year. In an "as treated" analysis, cumulative incidence of acute GI GVHD at day +180 was 0% and 12.5% in recipients of vitamin A and placebo, respectively (P = .02), and cumulative incidence of chronic GVHD was 2.7% and 15% in recipients of vitamin A and placebo, respectively (P = .01). The only possibly attributable toxicity was asymptomatic grade 3 hyperbilirubinemia in 1 recipient of vitamin A at day +30, which self-resolved. Absolute CCR9+ CD8+ effector memory T cells, reflecting gut T-cell trafficking, were lower in the vitamin A arm at day +30 after HSCT (P = .01). Levels of serum amyloid A-1, a vitamin A transport protein with proinflammatory effects, were lower in the vitamin A arm. The vitamin A arm had lower interleukin-6 (IL-6), IL-8, and suppressor of tumorigenicity 2 levels and likely a more favorable gut microbiome and short chain fatty acids. Pre-HSCT oral vitamin A is inexpensive, has low toxicity, and reduces GVHD. This trial was registered at www.ClinicalTrials.gov as NCT03202849.

Detection of Bronchiolitis Obliterans Syndrome after Pediatric Hematopoietic Stem Cell Transplantation: An Official American Thoracic Society Clinical Practice Guideline.

Background: Many children undergo allogeneic hematopoietic stem cell transplantation (HSCT) for the treatment of malignant and nonmalignant conditions. Unfortunately, pulmonary complications occur frequently post-HSCT, with bronchiolitis obliterans syndrome (BOS) being the most common noninfectious pulmonary complication. Current international guidelines contain conflicting recommendations regarding post-HSCT surveillance for BOS, and a recent NIH workshop highlighted the need for a standardized approach to post-HSCT monitoring. As such, this guideline provides an evidence-based approach to detection of post-HSCT BOS in children. Methods: A multinational, multidisciplinary panel of experts identified six questions regarding surveillance for, and evaluation of, post-HSCT BOS in children. A systematic review of the literature was undertaken to answer each question. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations addressing the role of screening pulmonary function testing and diagnostic tests in children with suspected post-HSCT BOS were made. Following a Delphi process, new diagnostic criteria for pediatric post-HSCT BOS were also proposed. Conclusions: This document provides an evidence-based approach to the detection of post-HSCT BOS in children while also highlighting considerations for the implementation of each recommendation. Further, the document describes important areas for future research.

Complement blockade for TA-TMA: lessons learned from a large pediatric cohort treated with eculizumab.

Overactivated complement is a high-risk feature in hematopoietic stem cell transplant (HSCT) recipients with transplant-associated thrombotic microangiopathy (TA-TMA), and untreated patients have dismal outcomes. We present our experience with 64 pediatric HSCT recipients who had high-risk TA-TMA (hrTA-TMA) and multiorgan injury treated with the complement blocker eculizumab. We demonstrate significant improvement to 66% in 1-year post-HSCT survival in treated patients from our previously reported untreated cohort with same hrTA-TMA features that had 1-year post-HSCT survival of 16.7%. Responding patients benefited from a brief but intensive course of eculizumab using pharmacokinetic/pharmacodynamic-guided dosing, requiring a median of 11 doses of eculizumab (interquartile range [IQR] 7-20). Treatment was discontinued because TA-TMA resolved at a median of 66 days (IQR 41-110). Subjects with higher complement activation measured by elevated blood sC5b-9 at the start of treatment were less likely to respond (odds ratio, 0.15; P = .0014) and required more doses of eculizumab (r = 0.43; P = .0004). Patients with intestinal bleeding had the fastest eculizumab clearance, required the highest number of eculizumab doses (20 vs 9; P = .0015), and had lower 1-year survival (44% vs 78%; P = .01). Over 70% of survivors had proteinuria on long-term follow-up. The best glomerular filtration rate (GFR) recovery in survivors was a median 20% lower (IQR, 7.3%-40.3%) than their pre-HSCT GFR. In summary, complement blockade with eculizumab is an effective therapeutic strategy for hrTA-TMA, but some patients with severe disease lacked a complete response, prompting us to propose early intervention and search for additional targetable endothelial injury pathways.

Single-center results reporting improved hematopoietic stem cell mobilization success in pediatric and young adult patients with solid tumors and lymphoma.

BACKGROUND: High-dose chemotherapy with autologous hematopoietic stem cell transplantation (auto-HSCT) is an established treatment for pediatric and young adult patients with solid tumors and lymphomas. Plerixafor is a CXC chemokine receptor type 4 (CXCR4) antagonist that can be used with granulocyte colony stimulating factor (G-CSF) to amplify the mobilization of hematopoietic stem cells (HSCs). METHODS: We performed a retrospective analysis of 167 pediatric solid tumor and lymphoma patients from January 2010 to July 2020 in whom HSCs were mobilized using G-CSF alone or with plerixafor. RESULTS: Thirteen heavily pretreated patients (33.3%) required twice-daily dosing of G-CSF compared to five patients (3.9%) in the not heavily pretreated group (p = .0005). Fourteen heavily pretreated patients (35.9%) required plerixafor compared to four patients (3.1%) in the comparison cohort (p = .0002). The number of mobilization days was similar between both cohorts, with 5 days (range 3-11 days) in the heavily pretreated group and 5 days (range 3-13 days) in the not heavily pretreated group (p = .55). The number of harvest days was 2 days (range 1-5 days) in the heavily pretreated group and 1 day (range 1-4 days) in the not heavily pretreated group (p = .0025). The final cluster of differentiation (CD)34+ /kilogram (kg) count was 9.52 × 106 /kg among heavily pretreated patients compared to 34.99 × 106 /kg CD34+ cells in the comparison group (p < .0001). Three heavily pretreated patients (7.7%) failed HSC mobilization. CONCLUSIONS: Patients at the highest risk for poor HSC mobilization can be successfully treated with more frequent G-CSF dosing or G-CSF with plerixafor in a large majority of cases.

Comparison of levetiracetam versus phenytoin/fosphenytoin for busulfan seizure prophylaxis at a pediatric institution.

INTRODUCTION: Busulfan is a chemotherapy agent used in hematopoietic stem cell transplant (HSCT) conditioning regimens. Busulfan is associated with tonic-clonic seizures in ~10% of patients if administered without seizure prophylaxis. Historically, phenytoin was the most commonly utilized seizure prophylaxis agent; however, phenytoin is associated with CYP450 drug interactions and potentially increases the clearance of busulfan. Levetiracetam is being used more recently for busulfan seizure prophylaxis and is not associated with drug-drug interactions; however, data supporting use in pediatric patients are limited. The primary objective is to determine whether there is any difference in seizure rates or safety profile between phenytoin and levetiracetam when used for seizure prophylaxis. METHODS: We conducted a retrospective chart review including patients who received busulfan between 2010 and 2019 were identified. The data were evaluated to compare the incidence of busulfan-induced seizures in HSCT patients receiving either phenytoin or levetiracetam and to determine the impact of drug-drug interactions on treatment outcomes/adverse events. RESULTS: A total of 342 patients were included with a median age of six years. Overall, five patients within the phenytoin group (n = 126) (4%) and zero patients in the levetiracetam group (n = 216) experienced a seizure (P = .007). There were no differences in liver enzyme elevations, recurrence rates of primary disease, and veno-occlusive disease. CONCLUSION: Levetiracetam is effective at preventing seizures associated with busulfan administration with no clinically significant adverse effects when compared to phenytoin.

Overproduction of the AlgT Sigma Factor Is Lethal to Mucoid Pseudomonas aeruginosa.

Pseudomonas aeruginosa isolates from chronic lung infections often overproduce alginate, giving rise to the mucoid phenotype. Isolation of mucoid strains from chronic lung infections correlates with a poor patient outcome. The most common mutation that causes the mucoid phenotype is called mucA22 and results in a truncated form of the anti-sigma factor MucA that is continuously subjected to proteolysis. When a functional MucA is absent, the cognate sigma factor, AlgT, is no longer sequestered and continuously transcribes the alginate biosynthesis operon, leading to alginate overproduction. In this work, we report that in the absence of wild-type MucA, providing exogenous AlgT is toxic. This is intriguing, since mucoid strains endogenously possess high levels of AlgT. Furthermore, we show that suppressors of toxic AlgT production have mutations in mucP, a protease involved in MucA degradation, and provide the first atomistic model of MucP. Based on our findings, we speculate that mutations in mucP stabilize the truncated form of MucA22, rendering it functional and therefore able to reduce toxicity by properly sequestering AlgT.IMPORTANCEPseudomonas aeruginosa is an opportunistic bacterial pathogen capable of causing chronic lung infections. Phenotypes important for the long-term persistence and adaption to this unique lung ecosystem are largely regulated by the AlgT sigma factor. Chronic infection isolates often contain mutations in the anti-sigma factor mucA, resulting in uncontrolled AlgT and continuous production of alginate in addition to the expression of ∼300 additional genes. Here, we report that in the absence of wild-type MucA, AlgT overproduction is lethal and that suppressors of toxic AlgT production have mutations in the MucA protease, MucP. Since AlgT contributes to the establishment of chronic infections, understanding how AlgT is regulated will provide vital information on how P. aeruginosa is capable of causing long-term infections.

Modeling rectal cancer to advance neoadjuvant precision therapy.

Progress in rectal cancer therapy has been hindered by the lack of effective disease-specific preclinical models that account for the unique molecular profile and biology of rectal cancer. Thus, we developed complementary patient-derived xenograft (PDX) and subsequent in vitro tumor organoid (PDTO) platforms established from preneoadjuvant therapy rectal cancer specimens to advance personalized care for rectal cancer patients. Multiple endoscopic samples were obtained from 26 Stages 2 and 3 rectal cancer patients prior to receiving 5FU/RT and implanted subcutaneously into NSG mice to generate 15 subcutaneous PDXs. Second passaged xenografts demonstrated 100% correlation with the corresponding human cancer histology with maintained mutational profiles. Individual rectal cancer PDXs reproduced the 5FU/RT response observed in the corresponding human cancers. Similarly, rectal cancer PDTOs reproduced significant heterogeneity in cellular morphology and architecture. PDTO in vitro 5FU/RT treatment response replicated the clinical 5FU/RT neoadjuvant therapy pathologic response observed in the corresponding patient tumors (p < 0.05). The addition of cetuximab to the 5FU/RT regiment was significantly more sensitive in the rectal cancer PDX and PDTOs with wild-type KRAS compared to mutated KRAS (p < 0.05). Considering the close relationship between the patient's cancer and the corresponding PDX/PDTO, rectal cancer patient-derived research platforms represent powerful translational research resources as population-based tools for biomarker discovery and experimental therapy testing. In addition, our findings suggest that cetuximab may enhance RT effectiveness by improved patient selection based on mutational profile in addition to KRAS or by developing a protocol using PDTOs to identify sensitive patients.

Improving Oral Health and Modulating the Oral Microbiome to Reduce Bloodstream Infections from Oral Organisms in Pediatric and Young Adult Hematopoietic Stem Cell Transplantation Recipients: A Randomized Controlled Trial.

Bloodstream infections (BSIs) from oral organisms are a significant cause of morbidity and mortality in hematopoietic stem cell transplantation (HSCT) recipients. There are no proven strategies to decrease BSIs from oral organisms. The aim of this study was to evaluate the impact of daily xylitol wipes in improving oral health, decreasing BSI from oral organisms, and modulating the oral microbiome in pediatric HSCT recipients. This was a single-center 1:1 randomized controlled trial in pediatric HSCT recipients age >2 years. Age-matched healthy children were enrolled to compare the oral microbiome. The oral hygiene standard of care (SOC) group continued to receive the standard oral hygiene regimen. The xylitol group received daily oral xylitol wipes (with .7 g xylitol) in addition to the SOC. The intervention started from the beginning of the transplantation chemotherapy regimen and extended to 28 days following transplantation. The primary outcome was oral health at interval time points, and secondary outcomes included BSIs from oral organisms in the first 30 days following transplantation, oral microbiome abundance, and diversity and oral pathogenic organism abundance. The study was closed early due to efficacy after an interim analysis of the first 30 HSCT recipients was performed (SOC group, n = 16; xylitol group, n = 14). The xylitol group had a significantly lower rate of gingivitis at days 7, 14, and 28 following transplantation (P = .031, .0039, and .0005, respectively); oral plaque at days 7 and 14 (P = .045 and .0023, respectively); and oral ulcers >10 mm at day 14 (P = .049) compared with the SOC group. The xylitol group had no BSI from oral organisms compared with the SOC group, which had 4 (P = .04). The xylitol group had significantly lower abundance of potential BSI pathogens, such as Staphylococcus aureus (P = .036), Klebsiella pneumoniae (P = .033), and Streptococcus spp (P = .011) at the day after transplantation compared with the SOC group. Healthy children and young adults had significantly increased oral microbiome diversity compared with all HSCT recipients (P < .001). The addition of xylitol to standard oral care significantly improves oral health, decreases BSI from oral organisms, and decreases the abundance of pathogenic oral organisms in pediatric and young adult HSCT recipients.

Thinking Beyond HLH: Clinical Features of Patients with Concurrent Presentation of Hemophagocytic Lymphohistiocytosis and Thrombotic Microangiopathy.

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive immune system activation driven mainly by high levels of interferon gamma. The clinical presentation of HLH can have considerable overlap with other inflammatory conditions. We present a cohort of patients with therapy refractory HLH referred to our center who were found to have a simultaneous presentation of complement-mediated thrombotic microangiopathy (TMA). Twenty-three patients had therapy refractory HLH (13 primary, 4 EVB-HLH, 6 HLH without known trigger). Sixteen (69.6%) met high-risk TMA criteria. Renal failure requiring renal replacement therapy, severe hypertension, serositis, and gastrointestinal bleeding were documented only in patients with HLH who had concomitant complement-mediated TMA. Patients with HLH and without TMA required ventilator support mainly due to CNS symptoms, while those with HLH and TMA had respiratory failure predominantly associated with pulmonary hypertension, a known presentation of pulmonary TMA. Ten patients received eculizumab for complement-mediated TMA management while being treated for HLH. All patients who received the complement blocker eculizumab in addition to the interferon gamma blocker emapalumab had complete resolution of their TMA and survived. Our observations suggest co-activation of both interferon and complement pathways as a potential culprit in the evolution of thrombotic microangiopathy in patients with inflammatory disorders like refractory HLH and may offer novel therapeutic approaches for these critically ill patients. TMA should be considered in children with HLH and multi-organ failure, as an early institution of a brief course of complement blocking therapy in addition to HLH-targeted therapy may improve clinical outcomes in these patients.

The histone-like protein AlgP regulon is distinct in mucoid and nonmucoid Pseudomonas aeruginosa and does not include alginate biosynthesis genes.

The opportunistic bacterial pathogen Pseudomonas aeruginosa causes acute and chronic infections that are notoriously difficult to treat. In people with cystic fibrosis, P. aeruginosa can cause lifelong lung infections, and isolation of mucoid P. aeruginosa, resulting from the overproduction of alginate, is associated with chronic infection. The histone-like protein AlgP has previously been implicated in the control of alginate gene expression in mucoid strains, but this regulation is unclear. To explore AlgP in further detail, we deleted algP in mucoid strains and demonstrated that the deletion of algP did not result in a nonmucoid phenotype or a decrease in alginate production. We showed that the algP promoter is expressed by both the nonmucoid strain PAO1 and the isogenic mucoid strain PDO300, suggesting that there may be genes that are differentially regulated between these strains. In support of this, using RNA sequencing, we identified a small AlgP regulon that has no significant overlap between PAO1 and PDO300 and established that alginate genes were not differentially regulated by the deletion of algP. Of note, we found that deleting algP in PAO1 increased expression of the nitric oxide operon norCBD and the nitrous oxide reductase genes nosRZ and subsequently promoted growth of PAO1 under anaerobic conditions. Altogether, we have defined a narrow regulon of genes controlled by AlgP and provided evidence that alginate production is not greatly affected by AlgP, countering the long-standing premise in the field.

Ibrutinib for the treatment of chronic graft-vs-host disease in pediatric hematopoietic stem cell transplant patients: A single-center experience.

cGVHD is a significant cause of morbidity and mortality after transplant. Ibrutinib has been studied as treatment for cGVHD in the adult population. Pediatric dosing and safety of ibrutinib are unknown. We conducted a retrospective review on the use of ibrutinib in 22 children with cGVHD at Cincinnati Children's Hospital Medical Center. All patients received a dose of 250 mg/m2 orally, once daily. Responses were measured at 6 months after drug initiation using the 2014 NIH consensus panel response criteria. Twenty-two patients of median age 13.5 years received ibrutinib. cGVHD grades were severe (n = 15), moderate (n = 6), and mild (n = 1). Eight patients stopped ibrutinib prior to 3 months due to adverse events or death and could not be evaluated for 6-month response. Of the 14 evaluable patients, 12 achieved a partial response at 6 months and two patients had progressive disease. Seven evaluable patients with lung involvement had stable lung function at 6 months. One patient had EBV reactivation, and one patient developed pneumococcal sepsis despite appropriate prophylaxis while on ibrutinib therapy. No fungal infections occurred while on ibrutinib. Adverse events leading to discontinuation included recurrent fevers without a source, extensive bruising, oral bleeding, gastrointestinal distress, lower GI bleeding, dizziness, elevated transaminases, and pneumococcal sepsis. Ibrutinib administration of 250 mg/m2 oral daily shows promising responses in pediatric cGVHD. Pediatric-focused pharmacokinetic-directed studies are needed to establish optimal dosing and define efficacy in children.

Busulfan Pharmacokinetics and Precision Dosing: Are Patients with Fanconi Anemia Different?

It is well known that pharmacokinetics (PK)-guided busulfan (BU) dosing increases engraftment rates and lowers hepatotoxicity in patients undergoing hematopoietic cell transplantation (HCT). However, there are no published PK data in patients with Fanconi anemia (FA), who are known to have baseline DNA repair defect and related inherent sensitivity to chemotherapy. In our prospective, multi-institutional study of alternative donor HCT for FA using chemotherapy-only conditioning, we replaced the single dose of total-body irradiation with BU at initial doses of 0.8 to 1.0 mg/kg and 0.6 to 0.8 mg/kg given i.v. every 12 hours for 4 doses. Patients received the first dose of i.v. busulfan on day -8, and blood levels for PK were obtained. PK samples were drawn following completion of infusion. BU PK levels were collected at 2 hours, 2 hours and 15 minutes, and 4, 5, 6, and 8 hours from the start of infusion. The remaining 3 doses of BU were given on days -7 and -6. Thirty-seven patients with available BU PK data with a median age of 9.2 years (range, 4.3 to 44 years) are included in the final analyses. The overall BU PK profile in patients with FA is similar to non-FA patients after considering their body weight. In our cohort, a strong correlation between BU clearance and weight supports current practice of per kilogram dosing. However, not surprisingly, we show that the disease (ie, host) sensitivity related to FA is the main determinant of total dose of BU that can be safely administered to patients in this high-risk population. On the basis of our results, we propose an optimal BU concentration at steady-state level of ≤350 ng/mL (equivalent to total cumulative exposure of 16.4 mg*h/L for 4 doses over 2 days) for patients with FA undergoing HCT. To our knowledge, this is the first and largest report of prospective BU PK in patients with FA undergoing HCT, providing an optimal BU target cutoff to achieve stable donor engraftment while avoiding excessive toxicity.

Lower levels of vitamin A are associated with increased gastrointestinal graft-versus-host disease in children.

Vitamin A promotes development of mucosal tolerance and enhances differentiation of regulatory T cells. Vitamin A deficiency impairs epithelial integrity, increasing intestinal permeability. We hypothesized that higher vitamin A levels would reduce the risk of graft-versus-host disease (GVHD) through reduced gastrointestinal (GI) permeability, reduced mucosal injury, and reduced lymphocyte homing to the gut. We tested this hypothesis in a cohort study of 114 consecutive patients undergoing allogeneic stem cell transplant. Free vitamin A levels were measured in plasma at day 30 posttransplant. GI GVHD was increased in patients with vitamin A levels below the median (38% vs 12.4% at 100 days, P = .0008), as was treatment-related mortality (17.7% vs 7.4% at 1 year, P = .03). Bloodstream infections were increased in patients with vitamin A levels below the median (24% vs 8% at 1 year, P = .03), supporting our hypothesis of increased intestinal permeability. The GI mucosal intestinal fatty acid-binding protein was decreased after transplant, confirming mucosal injury, but was not correlated with vitamin A levels, indicating that vitamin A did not protect against mucosal injury. Expression of the gut homing receptor CCR9 on T-effector memory cells 30 days after transplant was increased in children with vitamin A levels below the median (r = -0.34, P = .03). Taken together, these data support our hypothesis that low levels of vitamin A actively promote GI GVHD and are not simply a marker of poor nutritional status or a sicker patient. Vitamin A supplementation might improve transplant outcomes.

The Natural Product Elegaphenone Potentiates Antibiotic Effects against Pseudomonas aeruginosa.

Natural products represent a rich source of antibiotics that address versatile cellular targets. The deconvolution of their targets via chemical proteomics is often challenged by the introduction of large photocrosslinkers. Here we applied elegaphenone, a largely uncharacterized natural product antibiotic bearing a native benzophenone core scaffold, for affinity-based protein profiling (AfBPP) in Gram-positive and Gram-negative bacteria. This study utilizes the alkynylated natural product scaffold as a probe to uncover intriguing biological interactions with the transcriptional regulator AlgP. Furthermore, proteome profiling of a Pseudomonas aeruginosa AlgP transposon mutant provided unique insights into the mode of action. Elegaphenone enhanced the elimination of intracellular P. aeruginosa in macrophages exposed to sub-inhibitory concentrations of the fluoroquinolone antibiotic norfloxacin.

Combination of High-Dose Methylprednisolone and Defibrotide for Veno-Occlusive Disease in Pediatric Hematopoietic Stem Cell Transplant Recipients.

Veno-occlusive disease (VOD) is a serious complication of hematopoietic stem cell transplant (HSCT), with high mortality in severe cases and until recently very limited therapeutic options consisting largely of supportive care. Defibrotide was recently approved in the United States for the treatment of severe VOD in patients with renal or pulmonary dysfunction after HSCT. Our group previously published on the use of high-dose methylprednisolone (500 mg/m2 per dose every 12 hours for 6 doses) in patients with VOD, showing good success. A small subset of these individuals were also treated with defibrotide, but additional studies using the combination of high-dose methylprednisolone and defibrotide for the treatment of VOD are lacking. We present a single-institution retrospective chart review of 15 HSCT patients with VOD treated with the combination of high-dose methylprednisolone and defibrotide. VOD developed at a median of 17 days post-HSCT, and combination therapy was initiated within 1 day of VOD diagnosis. Twelve of 15 patients (80%) had multiorgan failure. Our single-center experience using both high-dose methylprednisolone and defibrotide showed a day +100 survival rate of 73% and an overall VOD complete resolution rate of 66.7%, higher than the rates reported in the recent literature using defibrotide alone (40% to 50% day +100 overall survival). These data suggest that the combination of high-dose steroids and defibrotide may be superior to defibrotide alone and warrant further investigation.

Single Ultra-High-Dose Cholecalciferol to Prevent Vitamin D Deficiency in Pediatric Hematopoietic Stem Cell Transplantation.

Vitamin D deficiency is prevalent among childhood hematopoietic stem cell transplantation (HSCT) recipients and associated with inferior survival at 100 days after transplantation. Achieving and maintaining therapeutic vitamin D levels in HSCT recipients is extremely challenging in the first 3 to 6 months after transplantation due to poor compliance in the setting of mucositis and the concomitant use of critical transplantation drugs that interfere with vitamin D absorption. We sought to evaluate the safety and efficacy of a single, ultra-high-dose of vitamin D given before childhood HSCT to maintain levels in a therapeutic range during the peritransplantation period. Ten HSCT recipients with pretransplantation 25-OH vitamin D (25OHD) level <50 ng/mL and with no history of hypercalcemia, nephrolithiasis, or pathological fractures were enrolled on this pilot study. A single enteral vitamin D dose (maximum 600,000 IU) was administered to each patient based on weight and pretransplantation vitamin D level before the day of HSCT. Vitamin D levels between 30 and 150 ng/mL were considered therapeutic. All patients received close clinical observation and monitoring of 25OHD levels, calcium, phosphate, parathyroid hormone, urine calcium/creatinine ratio, and n-telopeptide for safety and efficacy assessment. The mean age of the study subjects was 5.8 ± 4.9 years, and the mean pretransplantation 25OHD level was 28.9 ± 13.1 ng/mL. All patients tolerated single, ultra-high-oral dose of vitamin D under direct medical supervision. No other oral vitamin D supplements were administered during the observation window of 8 weeks. Three of 10 patients received 400 IU/day of vitamin D in parenteral nutrition only for 5 days during the study window. A mean peak serum vitamin D level of 80.4 ± 28.6 ng/mL was reached at a median of 9 days after the vitamin D dose. All patients achieved a therapeutic vitamin D level of >30 ng/mL. Mean vitamin D levels were sustained at or above 30 ng/mL during the 8-week observation window. There were no electrolyte abnormalities attributed to the ultra-high-dose of vitamin D. Most patients had mildly elevated urine calcium/creatinine ratios during treatment, but none showed clinical or radiologic signs of nephrocalcinosis or nephrolithiasis. Our findings indicate that single ultra-high-oral dose vitamin D treatment given just before HSCT is safe and well tolerated in the immediate peritransplant period in children. Patients in our study were able to achieve and sustain therapeutic vitamin D levels throughout the critical period during which vitamin D insufficiency is associated with decreased overall survival. Larger prospective studies are needed to address the impact of single ultra-high-dose vitamin D treatment on HSCT outcomes.

The clinical implications of immunogenomics in colorectal cancer: A path for precision medicine.

Colorectal cancer (CRC) remains the third most common malignancy and the second-leading cause of cancer-related deaths in the United States. Large multi-omic databases, such as The Cancer Genome Atlas and the International Colorectal Cancer Subtyping Consortium, have identified distinct molecular subtypes related to anatomy. The identification of genomic alterations in CRC is now critical because of the recent success and US Food and Drug Administration approval of pembrolizumab and nivolumab for microsatellite-instable tumors. In parallel, landmark studies have established the prognostic significance of the CRC tumor-infiltrating lymphocyte and the clinical impact of the tumor immune microenvironment. As a result, there is a growing appreciation for immunogenomics, the interconnected relation between tumor genomics and the immune microenvironment. The clinical implications of CRC immunogenomics continue to expand, and it will likely serve as a guide for next-generation immunotherapy strategies for improving outcomes for this disease. Cancer 2018;124:1650-9. © 2018 American Cancer Society.

Micafungin antifungal prophylaxis in children undergoing HSCT: can we give higher doses, less frequently? A pharmacokinetic study.

Background: Micafungin has a distinct advantage for antifungal prophylaxis in HSCT owing to its better safety profile, specifically in terms of hepatic and renal toxicity. In children, prophylactic micafungin is given as either 1 mg/kg every day or 3 mg/kg every other day. Objectives: We performed a prospective single-centre observational study that investigated the pharmacokinetics (PK) of a single 5 mg/kg dose of micafungin in young children undergoing HSCT, to ascertain the eventual feasibility of twice-weekly prophylactic administration. Methods: Nine children, ≤10 years of age undergoing HSCT, were enrolled and received a single intravenous dose of 5 mg/kg micafungin. Blood samples were obtained for PK analysis. Micafungin plasma concentration of >0.2 mg/L was chosen for target attainment (i.e. considered adequate prophylactic concentration). In addition, a population PK model was developed based on current and our previous PK study data. We also evaluated PK model-based simulation of PK profiles and target attainment using Monte Carlo simulation, for several dosing scenarios. Results: Mean clearance was 15.3 mL/h/kg (range 11.0-21.4 mL/h/kg) and the mean elimination half-life was 11.6 h (range 7.8-16.6 h). The mean concentration at 96 h was 0.11 mg/L (range 0.03-0.26 mg/L). Eleven percent (n = 1) of patients achieved target attainment at the end of 96 h. Simulation data showed that 1 mg/kg daily dosing and 3 mg/kg alternate-day dosing strategies achieved at least 99% and 81% target attainment, respectively, whereas a 5 mg/kg with 3 day-interval dosing strategy resulted in 64%, 72% and 84% target attainments in patients with body weights of 10, 20 and 30 kg, respectively. Conclusions: Micafungin at 5 mg/kg dosing did not achieve target attainment at the end of 96 h for antifungal prophylaxis in children undergoing HSCT. Simulation data suggest that a dosing strategy of micafungin at 5 mg/kg every 72 h is more likely to achieve target attainment in children with a higher body weight in comparison with children with a lower body weight. A cautious approach is advisable when using a high, but less frequent, dosing strategy in very young children.

Pretransplant Absolute Lymphocyte Counts Impact the Pharmacokinetics of Alemtuzumab.

Alemtuzumab is frequently used as part of reduced-intensity conditioning (RIC) regimens for allogeneic hematopoietic cell transplantation (HCT) in pediatric patients with nonmalignant diseases. We previously suggested an optimal day 0 targeted range of alemtuzumab, but there are no pediatric data regarding the pharmacokinetics (PK) of subcutaneous alemtuzumab to guide precision dosing trials. The goal of this study was to prospectively characterize alemtuzumab PK and to explore absolute lymphocyte count (ALC) as a predictor of interindividual variability. We prospectively enrolled 23 patients who received an alemtuzumab, fludarabine, and melphalan RIC regimen. Seventeen patients completed study and received 1 mg/kg alemtuzumab divided over 5 days subcutaneously, starting on day -14. The median age was 7 years (range, .5 to 18). Blood sampling for PK measurements and descriptive PK analyses were performed. The median maximum alemtuzumab concentration was 2.39 µg/mL (interquartile range, 1.98 to 2.92). The median terminal half-life was 5.2 days (interquartile range, 2.7 to 7.8). The median concentration at day 0 was 1.27 µg/mL (interquartile range, .35 to 1.51). Importantly, day 0 alemtuzumab levels and area under the curve negatively correlated with predose ALC and ALC area-time, respectively. In conclusion, we reported the PK of subcutaneous alemtuzumab given to pediatric allogeneic HCT patients and observed that almost all patients have persistence of lytic levels of alemtuzumab beyond day 0, at levels in excess of that needed to reduce the risk of acute graft-versus-host disease. Additionally, levels correlate with pretransplant ALC. These results will allow the development of population PK models for precision dosing trials.