BackgroundAtrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all‐cause mortality may guide interventions.Methods and ResultsIn the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose‐adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all‐cause mortality in the 14 171 participants in the intention‐to‐treat population. The median age was 73 years, and the mean CHADS 2 score was 3.5. Over 1.9 years of median follow‐up, 1214 (8.6%) patients died. Kaplan–Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all‐cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33–1.70, P<0.0001) and age ≥75 years (hazard ratio 1.69, 95% CI 1.51–1.90, P<0.0001) were associated with higher all‐cause mortality. Multiple additional characteristics were independently associated with higher mortality, with decreasing creatinine clearance, chronic obstructive pulmonary disease, male sex, peripheral vascular disease, and diabetes being among the most strongly associated (model C‐index 0.677).ConclusionsIn a large population of patients anticoagulated for nonvalvular atrial fibrillation, ≈7 in 10 deaths were cardiovascular, whereas <1 in 10 deaths were caused by nonhemorrhagic stroke or systemic embolism. Optimal prevention and treatment of heart failure, renal impairment, chronic obstructive pulmonary disease, and diabetes may improve survival.Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00403767.

Reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (allo-HCT) can cure patients with AML in CR. However, relapse after RIC allo-HCT may indicate heterogeneity in the stringency of CR. Strict definition of CR requires no evidence of leukemia by both morphologic and flow cytometric criteria. We re-evaluated 85 AML patients receiving RIC allo-HCT in CR to test if a strict definition of CR had direct implications for the outcome. These patients had leukemia immunophenotype documented at diagnosis and analyzed at allo-HCT. Eight (9.4%) had persistent leukemia by flow cytometric criteria at allo-HCT. The patients with immunophenotypic persistent leukemia had a significantly increased relapse (hazard ratio (HR): 3.7; 95% confidence interval (CI): 1.3-10.3, P ¼ 0.01) and decreased survival (HR: 2.9; 95% CI: 1.3-6.4, Po0.01) versus 77 patients in CR by both morphology and flow cytometry. However, the pre-allo-HCT bone marrow (BM) blast count (that is, 0-4%) was not significantly associated with risks of relapse or survival. These data indicate the presence of leukemic cells, but not the BM blast count affects survival. A strict morphologic and clinical lab flow cytometric definition of CR predicts outcomes after RIC allo-HCT, and therefore is critical to achieve at transplantation. Keywords: allogeneic hematopoietic cell transplantation; reduced-intensity conditioning regimen; AML; relapse; minimal residual disease; CR INTRODUCTIONAllogeneic hematopoietic SCT (allo-HCT) remains the most effective treatment for most patients with AML. 1 The two main mechanisms by which allo-HCT can cure AML are through the immunologically based GVL effect and leukemic cell cytoreduction by HCT conditioning. 2-5 Reduced-intensity conditioning (RIC) was introduced to allo-HCT more than a decade ago for patients who are older, had significant co-morbid conditions or poorer performance status. [6][7][8] The anti-neoplastic potency of these RIC HCT regimens relies primarily on the GVL effect rather than ablating all residual leukemic disease. 9 It is clear that patients with active leukemia had more relapse and worse OS after allo-HCT regardless of donor type or patient age. [10][11][12][13][14][15] Following allo-HCT, 40-60% of AML patients in CR1 enjoy long-term OS, whereas o20% of refractory or relapsed AML patients survive. 1,11 Yet even for allo-HCT during CR, relapse remains the most frequent complication of allo-HCT. 16 As relapse has been reported more frequently after RIC allo-HCT compared with myeloablative conditioning (MAC) allo-HCT in patients with AML, this suggests heterogeneity in the interpretation of a CR, which may be more important after RIC allo-HCT. [17][18][19][20][21][22][23] The CR definition updated in 2003 24 clearly requires no evidence of leukemia by flow cytometry in addition to the morphologic remission as reported: 'The presence of a unique phenotype (by flow cytometry) identical to what was found in the pretreatment specimen (for example, CD34, CD7 coexpression) should be viewed ...

Patients undergoing hematopoietic cell transplantation (HCT) with reduced intensity conditioning (RIC) commonly receive fludarabine. Higher exposure of F-ara-A, the active component of fludarabine, has been associated with a greater risk of non-relapse mortality (NRM). We sought to develop a model for fludarabine dosing in adult HCT recipients that would allow for precise dose targeting and predict adverse clinical outcomes. We developed a pharmacokinetic model from 87 adults undergoing allogeneic RIC HCT that predicts F-ara-A population clearance (Clpop) accounting for ideal body weight and renal function. We then applied the developed model to an independent cohort of 240 patients to identify whether model predictions were associated with NRM and acute graft vs host disease (GVHD). Renal mechanisms accounted for 35.6% of total F-ara-A Clpop. In the independent cohort the hazard ratio of NRM at day 100 was significantly higher in patients with predicted F-ara-A clearance (Clpred) <8.50 L/hr (p<0.01) and area under the curve (AUCpred)>6.00 μg*hr/mL (p=0.01). A lower Clpred was also associated with more NRM at month 6 (p=0.01) and trended towards significance at 12 months (p=0.05). In multivariate analysis, low fludarabine clearance trended towards higher risk of acute GVHD (p=0.05). We developed a model that predicts an individual's systemic F-ara-A exposure accounting for kidney function and weight. This model may provide guidance in dosing in overweight individuals and those with altered kidney function.

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Given age-related differences in drug metabolism and indications for hematopoietic stem cell transplantation (HSCT), personalized drug dosing of the conditioning regimen and post-transplant immunosuppression may reduce graft rejection, relapse rates, and toxicity in pediatric HSCT recipients. This manuscript summarizes the pharmacokinetic/dynamic data of HSCT conditioning and postgrafting immunosuppression, presented at the First Annual Pediatric Bone Marrow Transplant Consortium meeting in April 2013. Personalized dosing of BU to a target plasma exposure reduces graft rejection in children and improves relapse/toxicity rates in adults. Current weight-based dosing achieves the target BU exposure in only a minority (24.3%) of children. The initial BU dose should be based on the European Medicines Agency nomogram or population pharmacokinetic models to improve the numbers of children achieving the target exposure. There are limited pharmacokinetic data for treosulfan, cyclophosphamide, fludarabine, and alemtuzumab as HSCT conditioning in children. For postgrafting immunosuppression, mycophenolic acid (MPA) clearance may be increased in younger children (< 12 years). The preferred MPA pharmacokinetic monitoring parameters and target range are still evolving in HSCT recipients. Multi-institutional trials incorporating properly powered pharmacokinetic/dynamic studies are needed to assess the effect of variability in the plasma exposure of drugs/metabolites on clinical outcomes in pediatric HSCT recipients.

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Background No rabies post-exposure prophylaxis (PEP) failure has been documented in humans in the United States using modern cell-culture vaccines. In January 2021, an 84-year-old male died from rabies six months after being bitten by a rabid bat despite receiving timely rabies post-exposure prophylaxis (PEP). We investigated the cause of breakthrough infection. Methods We reviewed medical records, laboratory results, and autopsy findings, and performed whole genome sequencing (WGS) to compare patient and bat virus sequences. Storage, administration, and integrity of PEP biologics administered to the patient were assessed; samples from leftover rabies immunoglobulin were evaluated for potency. We conducted risk assessments for persons potentially exposed to the bat and for close contacts of the patient. Results Rabies virus antibodies present in serum and cerebrospinal fluid were non-neutralizing. Antemortem blood testing revealed the patient had unrecognized monoclonal gammopathy of unknown significance. Autopsy findings showed rabies meningoencephalitis and metastatic prostatic adenocarcinoma. Rabies virus sequences from the patient and the offending bat were identical by WGS. No deviations were identified in potency, quality control, administration, or storage of administered PEP. Of 332 persons assessed for potential rabies exposure to the case patient, three (0.9%) warranted PEP. Conclusion This is the first reported failure of rabies PEP in the Western Hemisphere using a cell culture vaccine. Host-mediated primary vaccine failure attributed to previously unrecognized impaired immunity is the most likely explanation for this breakthrough infection. Clinicians should consider measuring rabies neutralizing antibody titers after completion of PEP if there is any suspicion for immunocompromise.

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