Vaccination Ameliorates Cellular Inflammatory Responses in SARS-CoV-2 Breakthrough Infections

BACKGROUND

Data on cellular immune responses in persons with SARS-CoV-2 infection following vaccination are limited. The evaluation of these patients with SARS-CoV-2 breakthrough infections may provide insight into how vaccinations limit the escalation of deleterious host inflammatory responses.

METHODS

We conducted a prospective study of peripheral blood cellular immune responses to SARS-CoV-2 infection in 21 vaccinated patients, all with mild disease, and 97 unvaccinated patients stratified based on disease severity.

RESULTS

We enrolled 118 persons (50±14.5 years, 52 women) with SARS-CoV-2 infection. Compared to unvaccinated patients, vaccinated patients with breakthrough infections had a higher percentage of antigen presenting monocytes (HLA-DR+), mature monocytes (CD83+), functionally competent T cells (CD127+), and mature neutrophils (CD10+); and lower percentages of activated T cells (CD38+), activated neutrophils (CD64+) and immature B cells (CD127+CD19+). These differences widened with increased disease severity in unvaccinated patients. Longitudinal analysis showed that cellular activation decreased over time but persisted in unvaccinated patients with mild disease at 8-month follow-up.

CONCLUSIONS

Patients with SARS-CoV-2 breakthrough infections exhibit cellular immune responses that limit the progression of inflammatory responses and suggest mechanisms by which vaccination limits disease severity. These data may have implications for developing more effective vaccines and therapies.

High-affinity CD16 integration into a CRISPR/Cas9-edited CD38 locus augments CD38-directed antitumor activity of primary human natural killer cells

Background

Adoptive transfer of natural killer (NK) cells with augmented antibody-dependent cellular cytotoxicity (ADCC) capabilities and resistance to CD38 targeting has the potential to enhance the clinical anti-myeloma activity of daratumumab (DARA). Therefore, we sought to develop an efficient CRISPR/Cas9-based gene editing platform to disrupt CD38 expression (CD38 knockout (KO)) in ex vivo expanded NK cells and simultaneously arm CD38^KO NK cells with a high-affinity CD16 (CD16-158V) receptor.

Methods

CD38^KO human NK cells were generated using Cas9 ribonucleoprotein complexes. The platform was expanded by incorporating messenger RNA (mRNA) transfection of CD38^KO NK cells and targeted gene insertion at the CD38 locus to mediate gene knockin (KI). The capacity of these gene-edited NK cells to persist and mediate ADCC in the presence of DARA was tested in vitro and in a MM.1S xenograft mouse model.

Results

Highly efficient CD38 gene disruption was achieved in ex vivo expanded NK cells without affecting their proliferative or functional capacity. CD38 KO conferred resistance to DARA-induced NK cell fratricide, enabling persistence and augmented ADCC against myeloma cell lines in the presence of DARA in vitro and in a MM.1S xenograft mouse model. CD38^KO NK cells could be further modified by transfection with mRNA encoding a CD16-158V receptor, resulting in augmented DARA-mediated ADCC. Finally, we observed that a homology-directed repair template targeted to the CD38 locus facilitated an efficient 2-in-1 CD38 KO coupled with KI of a truncated CD34 reporter and CD16-158V receptor, with CD38^KO/CD16^KI NK cells demonstrating a further enhancement of DARA-mediated ADCC both in vitro and in vivo.

Conclusions

Adoptive immunotherapy using ex vivo expanded CD38^KO/CD16^KI NK cells has the potential to boost the clinical efficacy of DARA. By incorporating complementary genetic engineering strategies into a CD38 KO manufacturing platform, we generated NK cells with substantially augmented CD38-directed antitumor activity, establishing a strong rationale for exploring this immunotherapy strategy in the clinic.

170 Novel gene editing approach to enhance CD38-directed antitumor activity of primary human natural killer cells

Background

Natural killer (NK) cells play an important role in the antitumor responses of therapeutic monoclonal antibodies (mAbs) by mediating antibody-dependent cellular cytotoxicity (ADCC). ADCC occurs when tumor-ligated mAbs trigger NK cell killing by engaging CD16 on NK cells. Further, infusions of ex vivo expanded NK cells to potentiate the antitumor effects of mAbs is a promising immunotherapeutic approach. Daratumumab (DARA) is an anti-CD38 mAb used in the treatment of multiple myeloma (MM) that efficiently induces NK-mediated ADCC. However, CD38 is also expressed on NK cells, which leads to DARA-mediated NK cell destruction and impaired ADCC against MM. Harnessing NK cells to fully exploit the ADCC mechanism of DARA has the potential to improve DARA’s efficacy.

Methods

We developed a novel approach to maximize DARA-mediated ADCC against MM by protecting NK cells from DARA targeting while simultaneously boosting their ADCC capacity. We designed a CRISPR/Cas9-based gene editing platform to couple the disruption of CD38 expression with site-specific insertion of a gene encoding a high-affinity variant of CD16 at the CD38 locus in ex vivo expanded NK cells. To achieve this, we delivered a ribonucleoprotein composed of a single guide RNA and Cas9 nuclease to induce a double strand break within CD38, followed by infection with engineered AAV particles to deliver a homology directed repair template encoding either a truncated CD34 reporter or a FLAG-tagged high-affinity CD16 to be integrated at the site of CD38 gene disruption. Gene editing and insertion efficiency were assessed by flow cytometry for CD38, CD34, and/or FLAG. Transgene integration was confirmed by junction PCR.

Results

High CD38 knockout efficiency was achieved (90.1 ± 4.1%). Using an EF-1 alpha promoter-containing CD34 donor template, stable CD34 expression was seen in 90.2 ± 5.1% NK cells. Insertion of high-affinity CD16, as assessed by FLAG expression, was observed in 47.7 ± 6.1% of edited NK cells. NK cells modified to express high-affinity CD16 also exhibited a higher number of CD16-positive NK cells compared to unedited control NK cells (10.94 ± 1.8%). Functionally, CD38 knockout NK cells expressing high-affinity CD16 demonstrated augmented degranulation in ADCC assays and killing of daratumumab-treated MM cells compared to unedited control and CD38 knockout NK cells.

Conclusions

Novel gene editing techniques can be successfully applied to generate NK cells with enhanced antitumor capabilities. We established an efficient gene editing platform that can be utilized to produce NK cells optimized for adoptive combination with daratumumab.

Considerations in Pfizer-BioNTech COVID-19 vaccine preparation in clinic: Quality vs quantity

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

Subclinical hypernatraemia in a population of endurance racing sled dogs

Electrolyte disturbances occur in both human and veterinary endurance athletes; however, hypernatraemia is poorly documented in dogs. To further explore electrolyte changes in canine endurance athletes, we collected blood from two teams of dogs (n=16) participating in the mid-distance (336 km) CanAm race. Serum samples were collected 36 hours before the start and within 20 minutes of race completion. Serum was similarly collected from 18 dogs withdrawn after completing 264 km. Biochemical profiles and aldosterone assays were performed. Mean serum sodium (>155 mEq/l) and corrected chloride concentrations were significantly increased (P<0.01) from baseline in finishing and withdrawn dogs; however, unlike sodium, corrected chloride concentrations remained within the reference interval. Serum phosphorous, hepatic enzymes, cholesterol, creatinine kinase, blood urea nitrogen, globulin, glucose, and iron concentrations were also significantly increased (P<0.01) compared to baseline in both finishing and withdrawn dogs. Both mean serum aldosterone and urea nitrogen concentrations were significantly increased (P<0.01) from baseline in finishing and withdrawn dogs, with finishers having greater concentrations than withdrawn dogs (P<0.01). Pre-race and matched finishing dog populations were then used for correlation analysis. Serum sodium concentrations were significantly (P<0.01) and strongly correlated with chloride (r=0.92), albumin (r=0.88), total protein (r=0.87), globulin (r=0.81), and potassium (r=0.86). Serum sodium concentrations were not significantly correlated with serum aldosterone concentrations (r=0.04, P=0.87). This study uniquely described subclinical hypernatraemia in the canine endurance athlete. The data lend support of dehydration through free water loss as a cause of hypernatraemia likely compounded by insufficient replenishment by drinking. Elevations in aldosterone concentrations in the face of hypernatraemia may be attributed to concurrent extra-renal hypotonic water losses, counter regulatory hormone influences, or physiological hyperthermia. Such findings demonstrate a degree of clinical tolerance for euvolemic driven hypernatraemia in endurance sled dogs, while highlighting the need for appropriate water supplementation.

CD73 immune checkpoint defines regulatory NK cells within the tumor microenvironment

High levels of ecto-5'-nucleotidase (CD73) have been implicated in immune suppression and tumor progression, and have also been observed in cancer patients who progress on anti-PD-1 immunotherapy. Although regulatory T cells can express CD73 and inhibit T cell responses via the production of adenosine, less is known about CD73 expression in other immune cell populations. We found that tumor-infiltrating NK cells upregulate CD73 expression and the frequency of these CD73-positive NK cells correlated with larger tumor size in breast cancer patients. In addition, the expression of multiple alternative immune checkpoint receptors including LAG-3, VISTA, PD-1, and PD-L1 was significantly higher in CD73-positive NK cells than in CD73-negative NK cells. Mechanistically, NK cells transport CD73 in intracellular vesicles to the cell surface and the extracellular space via actin polymerization-dependent exocytosis upon engagement of 4-1BBL on tumor cells. These CD73-positive NK cells undergo transcriptional reprogramming and upregulate IL-10 production via STAT3 transcriptional activity, suppressing CD4-positive T cell proliferation and IFN-γ production. Taken together, our results support the notion that tumors can hijack NK cells as a means to escape immunity and that CD73 expression defines an inducible population of NK cells with immunoregulatory properties within the tumor microenvironment.

Compassionate Use of Remdesivir for Patients with Severe Covid-19

BACKGROUND

Remdesivir, a nucleotide analogue prodrug that inhibits viral RNA polymerases, has shown in vitro activity against SARS-CoV-2.

METHODS

We provided remdesivir on a compassionate-use basis to patients hospitalized with Covid-19, the illness caused by infection with SARS-CoV-2. Patients were those with confirmed SARS-CoV-2 infection who had an oxygen saturation of 94% or less while they were breathing ambient air or who were receiving oxygen support. Patients received a 10-day course of remdesivir, consisting of 200 mg administered intravenously on day 1, followed by 100 mg daily for the remaining 9 days of treatment. This report is based on data from patients who received remdesivir during the period from January 25, 2020, through March 7, 2020, and have clinical data for at least 1 subsequent day.

RESULTS

Of the 61 patients who received at least one dose of remdesivir, data from 8 could not be analyzed (including 7 patients with no post-treatment data and 1 with a dosing error). Of the 53 patients whose data were analyzed, 22 were in the United States, 22 in Europe or Canada, and 9 in Japan. At baseline, 30 patients (57%) were receiving mechanical ventilation and 4 (8%) were receiving extracorporeal membrane oxygenation. During a median follow-up of 18 days, 36 patients (68%) had an improvement in oxygen-support class, including 17 of 30 patients (57%) receiving mechanical ventilation who were extubated. A total of 25 patients (47%) were discharged, and 7 patients (13%) died; mortality was 18% (6 of 34) among patients receiving invasive ventilation and 5% (1 of 19) among those not receiving invasive ventilation.

CONCLUSIONS

In this cohort of patients hospitalized for severe Covid-19 who were treated with compassionate-use remdesivir, clinical improvement was observed in 36 of 53 patients (68%). Measurement of efficacy will require ongoing randomized, placebo-controlled trials of remdesivir therapy. (Funded by Gilead Sciences.).

A pilot trial of complement inhibition using eculizumab to overcome platelet transfusion refractoriness in human leukocyte antigen allo-immunized patients

Heavily transfused patients frequently develop human leukocyte antigen (HLA) allo-immunization resulting in platelet transfusion refractoriness and a high risk for life-threatening thrombocytopenia. Data suggest complement activation leading to the destruction of platelets bound by HLA allo-antibodies may play a pathophysiologic role in platelet refractoriness. Here we conducted a pilot trial to investigate the use of eculizumab, a monoclonal antibody that binds and inhibits C5 complement, to treat platelet transfusion refractoriness in allo-immunized patients with severe thrombocytopenia. A single eculizumab infusion was administered to 10 eligible patients, with four (40%) patients overcoming platelet refractories assessed measuring the corrected platelet count increment (CCI) 10-60 min and 18-24 h post transfusion. Responding patients had a reduction in the requirement for subsequent platelet transfusions and had higher post-transfusion platelet increments for 14 days following eculizumab administration. Remarkably, three of the four responders met CCI criteria for response despite receiving HLA-incompatible platelets. Our results suggest that eculizumab has the ability to overcome platelet transfusion refractoriness in patients with broad HLA allo-immunization. This study establishes proof of principle that complement inhibition can treat platelet transfusion refractoriness, laying the foundation for a large multicentre trial to assess the overall efficacy of this approach (ClinicalTrials.gov, identifier: NCT02298933).

Fatal encephalopathy with wild-type JC virus and ruxolitinib therapy

OBJECTIVE

JC virus (JCV) infection is a lytic infection of oligodendrocytes in progressive multifocal leukoencephalopathy; less common forms of central nervous system manifestations associated with JCV infection include granule cell neuronopathy, encephalopathy, and meningitis. Presented is the first case of fatal JCV encephalopathy after immunosuppressive therapy that included ruxolitinib.

METHODS

Postmortem analysis included next generation sequencing, Sanger sequencing, tissue immunohistochemistry, and formalin-fixed hemisphere 7T magnetic resonance imaging.

RESULTS

JCV DNA isolated from postmortem tissue samples identified a novel 12bp insertion that altered the transcription site binding pattern in an otherwise "wild-type virus," which has long been thought to be the nonpathogenic form of JCV. Anti-VP1 staining demonstrated infection in cortical neurons, hippocampal neurons, and glial and endothelial cells.

INTERPRETATION

This expands the spectrum of identified JCV diseases associated with broad-spectrum immunosuppression, including JAK-STAT inhibitors, and sheds light on an additional neurotropic virus strain of the archetype variety. ANN NEUROL 2019;86:878-884.

Abstract 1434: The Costimulatory Signal Domains 4-1BB and CD3ζ Do Not Improve the Function of CD16A Chimeric Antigen Receptor Transduced NK Cells

Chimeric Antigen Receptors (CAR)-T cells are genetically modified to express an extracellular binding domain, transmembrane domain and intracellular signaling domain. The extracellular binding domain is usually derived from antibodies; however, it can be replaced with other ligand-receptor binding systems, such as with an Fc receptor. CD16A has been tested in second-generation 4-1BB-CD3ζ CAR T cells and NK cell lines (NK-92) and enhances tumor killing; however, it is not clear whether these cells provide superior tumor killing compared to cells modified to express CD16A alone.

In this study, we designed three CAR constructs containing the extracellular binding domain of high affinity mutant CD16A (CD16A-V158) and intracellular signal through 4-1 BB-CD3ζ that differed in leader sequences and transmembrane domains. CAR1 contained the CD16A leader and CD16A transmembrane domain; CAR2 had the CD16A leader and CD8α transmembrane domain; CAR3 contained the CD8α leader and CD8α transmembrane domain. When transduced into Jurkat cells via lentivirus, CD16A V158 and all three CARs showed stable high surface expression of CD16A (&gt; 70%). In contrast, NK-92 cells were only successfully transduced to express CD16 by CD16A V158 (29.8%), CAR2 (42.3%), and CAR3 (42.5%) with no expression of CD16A by CAR1. Transduced cells were sorted by FACs based on CD16A expression. All sorted cells showed &gt;90% stable expression of the constructs for up to 42 days post sorting. We observed a much higher CD16 MFI in cells transduced with CAR2 and CAR3 compared with CD16A V158. Western blotting with anti-CD3ζ identified the full assembly of CARs.

We then tested the function of the transduced cells by a Rituximab binding assay. Although there was no difference in binding to Rituximab at 0.01 and 0.1 mg/mL; CAR2 and CAR3 showed better binding at the 1 and 10 mg/mL. In a 4-hour coculture toxicity assay with 721.221 LCLs, CD16A V158 and CAR3 increased the target lysis by two-fold while CAR2 only showed a 50% increase. When cocultured with 721.221 HLA-E+ LCLs, a 721.221 subclone more resistant to killing by NK-92 cells, we observed similar tumor killing with CD16A V158 and CAR3 (killing doubled) in contrast to CAR2(killing increased by only 50%). We next tested against the B-cell line Raji and found that there was only a mild increase of target lysis with transduced NK-92 cells; however, the CD16A V158 and CAR3 still showed higher toxicity (around a 40% increase).

In summary, CAR2 and CAR3 expressed a higher CD16 MFI in NK cells and demonstrated better binding to Rituximab at1 and 10 mg/mL compared to CD16A V158; however, CAR3 and CD16A V158 had similar killing of target cells that was higher than was observed with CAR2. Our data indicate that NK cells transduced to have a CAR structure combining CD16A with 4-1BB-CD3ζ have augmented ADCC, although this augmentation is not superior to NK cells that are simply transduced to express CD16A alone.

Citation Format: Long Chen, Vicky Li, David Allan, Robert Reger, Elena Cherkasova, Stephanie Pierre, Stefan Barisic, David Granadier, Emily Levy, Giacomo Waller, Susan Doh, Mala Chakraborty, Kate Stringaris, Richard Childs. The Costimulatory Signal Domains 4-1BB and CD3ζ Do Not Improve the Function of CD16A Chimeric Antigen Receptor Transduced NK Cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1434.

Enhanced Bone Marrow Homing of Natural Killer Cells Following mRNA Transfection With Gain-of-Function Variant CXCR4R334X

Adoptive transfer of natural killer (NK) cells can induce remission in patients with relapsed/refractory leukemia and myeloma. However, to date, clinical efficacy of NK cell immunotherapy has been limited to a sub-fraction of patients. Here we show that steps incorporated in the ex vivo manipulation/production of NK cell products used for adoptive infusion, such as over-night IL-2 activation or cryopreservation followed by ex vivo expansion, drastically decreases NK cell surface expression of the bone marrow (BM) homing chemokine receptor CXCR4. Reduced CXCR4 expression was associated with dampened in vitro NK cell migration toward its cognate ligand stromal-derived factor-1α (SDF-1α). NK cells isolated from patients with WHIM syndrome carry gain-of-function (GOF) mutations in CXCR4 (CXCR4^R334X). Compared to healthy donors, we observed that NK cells expanded from WHIM patients have similar surface levels of CXCR4 but have a much stronger propensity to home to BM compartments when adoptively infused into NOD-scid IL2Rgamma^null (NSG) mice. Therefore, in order to augment the capacity of adoptively infused NK cells to home to the BM, we genetically engineered ex vivo expanded NK cells to express the naturally occurring GOF CXCR4^R334X receptor variant. Transfection of CXCR4^R334X-coding mRNA into ex vivo expanded NK cells using a clinically applicable method consistently led to an increase in cell surface CXCR4 without altering NK cell phenotype, cytotoxic function, or compromising NK cell viability. Compared to non-transfected and wild type CXCR4-coding mRNA transfected counterparts, CXCR4^R334X-engineered NK cells had significantly greater chemotaxis toward SDF-1α in vitro. Importantly, expression of CXCR4^R334X on expanded NK cells resulted in significantly greater BM homing following adoptive transfer into NSG mice compared to non-transfected NK cell controls. Collectively, these data suggest up-regulation of cell surface CXCR4^R334X on ex vivo expanded NK cells via mRNA transfection represents a novel approach to improve homing and target NK cell-based immunotherapies to BM where hematological malignancies reside.

The oral microbiome of patients undergoing treatment for severe aplastic anemia: a pilot study

The microbiome, an intriguing component of the human body, composed of trillions of microorganisms, has prompted scientific exploration to identify and understand its function and role in health and disease. As associations between microbiome composition, disease, and symptoms accumulate, the future of medicine hinges upon a comprehensive knowledge of these microorganisms for patient care. The oral microbiome may provide valuable and efficient insight for predicting future changes in disease status, infection, or treatment course. The main aim of this pilot study was to characterize the oral microbiome in patients with severe aplastic anemia (SAA) during their therapeutic course. SAA is a hematologic disease characterized by bone marrow failure which if untreated is fatal. Treatment includes either hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). In this study, we examined the oral microbiome composition of 24 patients admitted to the National Institutes of Health (NIH) Clinical Center for experimental SAA treatment. Tongue brushings were collected to assess the effects of treatment on the oral microbiome. Twenty patients received standard IST (equine antithymocyte globulin and cyclosporine) plus eltrombopag. Four patients underwent HSCT. Oral specimens were obtained at three time points during treatment and clinical follow-up. Using a novel approach to 16S rRNA gene sequence analysis encompassing seven hypervariable regions, results demonstrated a predictable decrease in microbial diversity over time among the transplant patients. Linear discriminant analysis or LefSe reported a total of 14 statistically significant taxa (p < 0.05) across time points in the HSCT patients. One-way plots of relative abundance for two bacterial species (Haemophilus parainfluenzae and Rothia mucilaginosa) in the HSCT group, show the differences in abundance between time points. Only one bacterial species (Prevotella histicola) was noted in the IST group with a p value of 0.065. The patients receiving immunosuppressive therapy did not exhibit a clear change in diversity over time; however, patient-specific changes were noted. In addition, we compared our findings to tongue dorsum samples from healthy participants in the Human Microbiome Project (HMP) database and found among HSCT patients, approximately 35% of bacterial identifiers (N = 229) were unique to this study population and were not present in tongue dorsum specimens obtained from the HMP. Among IST-treated patients, 45% (N = 351) were unique to these patients and not identified by the HMP. Although antibiotic use may have likely influenced bacterial composition and diversity, some literature suggests a decreased impact of antimicrobials on the oral microbiome as compared to their effect on the gut microbiome. Future studies with larger sample sizes that focus on the oral microbiome and the effects of antibiotics in an immunosuppressed patient population may help establish these potential associations.

Spleen and Liver Volumetrics as Surrogate Markers of Hepatic Venous Pressure Gradient in Patients With Noncirrhotic Portal Hypertension

Noncirrhotic portal hypertension (NCPH) is a rare disease that may lead to serious clinical consequences. Currently, noninvasive tools for the assessment of NCPH are absent. We investigated the utility of spleen and liver volumetrics as a marker of the presence and severity of portal hypertension in this population. A cohort of NCPH patients evaluated between 2003 and 2015 was retrospectively studied. The association of spleen and liver volumes with the hepatic venous pressure gradient (HVPG) level was evaluated using locally weighted scatterplot smoothing curves. A cohort of patients with viral hepatitis-related liver disease was used as controls. Of the 86 patients with NCPH evaluated during the study period, 75 (mean age, 35 ± 17; 73% males) were included in the final analysis. Patients with portal hypertension had significantly higher spleen and liver to body mass index (BMI) ratios compared to patients with HVPG <5 mm Hg (39.5 ± 27.9 versus 22.8 ± 10.6 cm3/kg/m2, P = 0.003; 91.1 ± 40.1 versus 71.4 ± 16.7 cm3/kg/m2, P = 0.014, for spleen/BMI and liver/BMI, respectively). In contrast to the patients with viral hepatitis, a positive linear correlation was observed in the NCPH cohort between spleen/BMI and liver/BMI (above a cutoff of 25 and 80 cm3/kg/m2, respectively) and HVPG level. Additionally, only in the NCPH cohort was an increase in spleen/BMI range quartile predictive of a higher prevalence of portal hypertension and clinically significant portal hypertension (trend, P = 0.014 and 0.031, respectively). Conclusion: Spleen and liver volumetrics may have utility in the assessment of NCPH as a noninvasive biomarker that can be performed using routine radiologic examinations. Further studies are needed to validate these findings. (Hepatology Communications 2018; 00:000-000).

Highly efficient IL-21 and feeder cell-driven ex vivo expansion of human NK cells with therapeutic activity in a xenograft mouse model of melanoma

Natural killer (NK) cells are promising antitumor effector cells, but the generation of sufficient NK cell numbers for adoptive immunotherapy remains challenging. Therefore, we developed a method for highly efficient ex vivo expansion of human NK cells. Ex vivo expansion of NK cells in medium containing IL-2 and irradiated clinical-grade feeder cells (EBV-LCL) induced a 22-fold NK cell expansion after one week that was significantly increased to 53-fold by IL-21. Repeated stimulation with irradiated EBV-LCL and IL-2 and addition of IL-21 at the initiation of the culture allowed sustained NK cell proliferation with 10¹¹-fold NK cell expansion after 6 weeks. Compared to naive NK cells, expanded NK cells upregulated TRAIL, NKG2D, and DNAM-1, had superior cytotoxicity against tumor cell lines in vitro and produced more IFNγ and TNF-α upon PMA/Iono stimulation. Most importantly, adoptive transfer of NK cells expanded using feeder cells, IL-2 and IL-21 led to significant inhibition of tumor growth in a melanoma xenograft mouse model, which was greater than with NK cells activated with IL-2 alone. Intriguingly, adoptively transferred NK cells maintained their enhanced production of IFNγ and TNF-α upon ex vivo restimulation, although they rapidly lost their capacity to degranulate and mediate tumor cytotoxicity after the in vivo transfer. In conclusion, we developed a protocol for ex vivo NK cell expansion that results in outstanding cell yields. The expanded NK cells possess potent antitumor activity in vitro and in vivo and could be utilized at high numbers for adoptive immunotherapy in the clinic.

Haploidentical cord transplantation-The best of both worlds

Haploidentical (haplo)-cord transplantation combines infusion of an umbilical cord blood (UCB) unit with CD34-selected cells usually from human leukocyte antigen (HLA) mismatched donors. Initial rapid count recovery from the haplo-hematopoietic progenitors, is gradually replaced by durable engraftment from UCB progenitors. UCB grafts used for haplo-cord are smaller, but better matched than those required for single or double UCB stem cell transplant (SCT). More than 200 patients with hematological malignancies have been transplanted. Median age was 54 years (range 17-74) and 77 were over age 60. One-year survival was 64% for patients with intermediate- and low-risk disease, with no deaths beyond 2 years. In high-risk disease, 1-year survival was 44%. In a comparison with patients undergoing double UCB SCT, haplo-cord transplant resulted in faster hematopoietic recovery, lower rates of acute and chronic graft-versus-host disease (GVHD), lower rates of disease recurrence, and improved GVHD- and relapse-free survival (GRFS). Excellent results were also reported for patients with aplastic anemia where 18 of 21 patients had sustained cord blood engraftment. Rates of GVHD and of disease recurrence after haplo-cord are encouraging. However, in the approximately 10% of patients with failure of the UCB graft disease recurrence is high, supporting the important role of UCB-mediated graft-versus-leukemia (GVL). Ongoing efforts are aimed at identifying determinants of UCB engraftment, at reducing rates of disease recurrence in high risk patients and at optimizing dose and schedule of ATG -necessary to avoid early haplo-graft rejection, but also contributing to early post-transplant immunocompromise. For those lacking haploidentical donors, unrelated donors have been successfully utilized.

Monoclonal gammopathy-associated pure red cell aplasia

Pure red cell aplasia (PRCA) is a rare disorder characterized by inhibition of erythroid precursors in the bone marrow and normochromic, normocytic anaemia with reticulocytopenia. Among 51 PRCA patients, we identified 12 (24%) patients having monoclonal gammopathy, monoclonal gammopathy of undetermined significance or smouldering multiple myeloma, with presence of monoclonal protein or abnormal serum free light chains and atypical bone marrow features of clonal plasmacytosis, hypercellularity and fibrosis. Thus far, three patients treated with anti-myeloma based therapeutics have responded with reticulocyte recovery and clinical transfusion independence, suggesting plasma cells play a key role in the pathogenesis of this specific monoclonal gammopathy-associated PRCA.

Spiritual Well-Being in Hispanic and Non-Hispanic Survivors of Allogeneic Hematopoietic Stem Cell Transplantation

Research suggests that spiritual well-being positively contributes to quality of life during and following cancer treatment. This relationship has not been well-described in ethnically diverse survivors of allogeneic transplantation.  This study compares spiritual well-being and quality of life of Hispanic (n = 69) and non-Hispanic (n = 102) survivors. Hispanic participants were significantly younger and reported significantly greater spiritual well-being than non-Hispanic survivors. Survivors with higher spiritual well-being had significantly better quality of life. Meaning and Peace significantly predicted quality of life. Although Hispanic survivors report greater spiritual well-being, Meaning and Peace, irrespective of ethnicity, have a salutary effect on quality of life.

Genome-wide detection of DNase I hypersensitive sites in single cells and FFPE tissue samples

DNase I hypersensitive sites (DHSs) provide important information on the presence of transcriptional regulatory elements and the state of chromatin in mammalian cells. Conventional DNase sequencing (DNase-seq) for genome-wide DHSs profiling is limited by the requirement of millions of cells. Here we report an ultrasensitive strategy, called single-cell DNase sequencing (scDNase-seq) for detection of genome-wide DHSs in single cells. We show that DHS patterns at the single-cell level are highly reproducible among individual cells. Among different single cells, highly expressed gene promoters and enhancers associated with multiple active histone modifications display constitutive DHS whereas chromatin regions with fewer histone modifications exhibit high variation of DHS. Furthermore, the single-cell DHSs predict enhancers that regulate cell-specific gene expression programs and the cell-to-cell variations of DHS are predictive of gene expression. Finally, we apply scDNase-seq to pools of tumour cells and pools of normal cells, dissected from formalin-fixed paraffin-embedded tissue slides from patients with thyroid cancer, and detect thousands of tumour-specific DHSs. Many of these DHSs are associated with promoters and enhancers critically involved in cancer development. Analysis of the DHS sequences uncovers one mutation (chr18: 52417839G>C) in the tumour cells of a patient with follicular thyroid carcinoma, which affects the binding of the tumour suppressor protein p53 and correlates with decreased expression of its target gene TXNL1. In conclusion, scDNase-seq can reliably detect DHSs in single cells, greatly extending the range of applications of DHS analysis both for basic and for translational research, and may provide critical information for personalized medicine.

Documenting stress in caregivers of transplantation patients: initial evidence of HPA dysregulation

There is growing evidence linking caregiver stress with an increased risk for morbidity and mortality. While the emotional and practical burden experienced by caregivers is well established, the physiological changes that may affect the caregiver's health are less understood. This study sought to compare self-reported stress, anxiety and depression along with neuroendocrine and immune markers of stress among adult caregivers of allogeneic hematopoietic stem cell transplantation patients during the acute transplant recovery period to matched non-caregivers controls. Biomarkers and self-reported data were collected at three points during the patient's HSCT: (1) before transplant, (2) after initial transplantation discharge (±7 days) and (3) 6 weeks after initial transplantation discharge. Mixed linear modeling was used to examine differences by group and time. Twenty-one caregivers and 20 controls completed all study procedures. The majority of caregivers were female (57% or 57.1%) and married (95.2%), with a mean age of 52 ± 11.4 years. Caregiver perceived stress, anxiety and depression scores were significantly higher than controls (p < 0.001) with effect sizes (ES) ranging from 1.37 to 1.80 and they did not change over time (p > 0.05) for either group. Caregivers had significantly lower serum cortisol levels than controls at both discharge (p = 0.013; ES = 0.81) and 6 weeks after discharge (p = 0.028; ES = 0.72) but exhibited no significant relationship between self-reported stress and serum cortisol. In addition, caregivers showed a significant inverse relationship between stress and epinephrine levels (r(s)=-0.654, p = 0.021). These findings support the evidence of the caregiving experience being stressful. The counter-intuitive relationship between cortisol and epinephrine might suggest dysregulation of the HPA axis and central nervous system but additional research on the physiological impact of caregiving is warranted.

CXCL10-induced migration of adoptively transferred human natural killer cells toward solid tumors causes regression of tumor growth in vivo

Adoptive infusion of natural killer (NK) cells is being increasingly explored as a therapy in patients with cancer, although clinical responses are thus far limited to patients with hematological malignancies. Inadequate homing of infused NK cells to the tumor site represents a key factor that may explain the poor anti-tumor effect of NK cell therapy against solid tumors. One of the major players in the regulation of lymphocyte chemotaxis is the chemokine receptor chemokine (C-X-C motif) receptor 3 (CXCR3) which is expressed on activated NK cells and induces NK cell migration toward gradients of the chemokine (C-X-C motif) ligand (CXCL9, 10 and 11). Here, we show that ex vivo expansion of human NK cells results in a tenfold increased expression of the CXCR3 receptor compared with resting NK cells (p = 0.04). Consequently, these NK cells displayed an improved migratory capacity toward solid tumors, which was dependent on tumor-derived CXCL10. In xenograft models, adoptively transferred NK cells showed increased migration toward CXCL10-transfected melanoma tumors compared with CXCL10-negative wild-type tumors, resulting in significantly reduced tumor burden and increased survival (median survival 41 vs. 32 days, p = 0.03). Furthermore, administration of interferon-gamma locally in the tumor stimulated the production of CXCL10 in subcutaneous melanoma tumors resulting in increased infiltration of adoptively transferred CXCR3-positive expanded NK cells. Our findings demonstrate the importance of CXCL10-induced chemoattraction in the anti-tumor response of adoptively transferred expanded NK cells against solid melanoma tumors.

The clinical and financial burden of pre-emptive management of cytomegalovirus disease after allogeneic stem cell transplantation-implications for preventative treatment approaches

BACKGROUND AIMS

Although cytomegalovirus (CMV) infection after allogeneic stem cell transplantation (SCT) is rarely fatal, the management of CMV by pre-emptive medication for viral reactivation has toxicity and carries a financial burden. New strategies to prevent CMV reactivation with vaccines and antiviral T cells may represent an advance over pre-emptive strategies but have yet to be justified in terms of transplantation outcome and cost.

METHODS

We compared outcomes and post-transplantation treatment cost in 44 patients who never required pre-emptive CMV treatment with 90 treated patients undergoing SCT at our institute between 2006 and 2012. Eighty-one subjects received CD34+ selected myeloablative SCT, 12 umbilical cord blood transplants, and 41 T-replete non-myeloablative SCT. One hundred nineteen patients (89%) were at risk for CMV because either the donor or recipient was seropositive. Of these, 90 patients (75.6%) reactivated CMV at a median of 30 (range 8-105) days after transplantation and received antivirals.

RESULTS

There was no difference in standard transplantation risk factors between the two groups. In multivariate modeling, CMV reactivation >250 copies/mL (odds ratio = 3, P < 0.048), total duration of inpatient IV antiviral therapy (odds ratio = 1.04, P < 0.001), type of transplantation (T-deplete vs. T-replete; odds ratio = 4.65, P < 0.017) were found to be significantly associated with increased non-relapse mortality. The treated group incurred an additional cost of antiviral medication and longer hospitalization within the first 6 months after SCT of $58,000 to $74,000 per patient.

CONCLUSIONS

Our findings suggest that to prevent CMV reactivation, treatment should be given within 1 week of SCT. Preventative treatment may improve outcome and have significant cost savings.

Voriconazole metabolism, toxicity, and the effect of cytochrome P450 2C19 genotype

BACKGROUND

Prospective evaluation of the antifungal drug, voriconazole, is needed to determine whether drug toxicity correlates with CYP2C19 genotype or serum concentrations of voriconazole or its metabolites.

METHODS

We conducted a prospective study of 95 patients to determine voriconazole toxicity and its relationship to genotype and serum levels of voriconazole and its two metabolites. Efficacy was not evaluated because, in most cases, the drug was given for empirical or prophylactic therapy.

RESULTS

Hallucinations occurred in 16 patients (16.8%), visual changes in 17 (17.9%), photosensitivity in 10 (10.5%), and hepatotoxicity in 6 (6.3%). There was no correlation between photosensitivity or hepatotoxicity and levels of voriconazole or metabolites. Patients with hallucinations had higher average voriconazole levels (4.5 vs 2.5 μg/mL) but with extensive overlap. The recommended oral dose of 200 mg did not provide consistently detectable serum voriconazole levels in adults. CYP2C19 and CYP2C9 genotypes had a minor influence over levels, though the 4 patients homozygous for the 2C19*2 genotype had higher average levels for voriconazole (4.3 vs 2.5 μg/mL) and lower N-oxide levels (1.6 vs 2.5 μg/mL).

CONCLUSIONS

CYP2C19 and 2C9 genotypes were not major determinants of voriconazole metabolism. No toxic serum level of voriconazole or its metabolites could be identified.

Active thrombopoiesis is associated with worse severity and activity of chronic GVHD

Chronic GVHD (cGVHD) is a major complication of allogeneic hematopoietic SCT. Post transplant thrombocytopenia in patients with cGVHD has been associated with poor outcome and its etiology is unclear. We investigated whether thrombopoiesis, assessed via measurement of the absolute immature platelet number (AIPN) in the blood, is impaired in cGVHD, and whether the level of thrombopoiesis correlates with the severity and activity of cGVHD as assessed via the National Institutes of Health (NIH) organ scoring system. We used a cohort of 110 well-characterized cGVHD patients, including 83 (75%) with severe cGVHD per NIH global score. Higher AIPN was associated with active therapeutic intent (P=0.026), lower Karnofsky score (P=0.0013), worse joint/fascia cGVHD (P=0.0005) and worse skin cGVHD (P=0.0044). AIPN correlated with platelet counts and was not correlated with ANC, WBC, C-reactive protein (CRP), absolute lymphocyte count (ALC), albumin, total and average NIH scores, or number of prior systemic therapies. AIPN values for cGVHD patients substantially overlapped those of the normal population. Higher AIPN, as marker of active thrombopoiesisis, was associated with worse severity and activity of cGVHD, especially skin and joints/fascia manifestations. Among patients with stable moderate or severe cGVHD, there was no evidence of hypoproduction of platelets. Future studies should further investigate the role of thrombopoiesis in cGVHD.

Human papillomavirus reactivation following treatment of genital graft-versus-host disease

Vaginal chronic graft-versus-host disease (cGVHD) is a common complication of stem cell transplantation. Human papillomavirus (HPV) disease can reactivate after transplantation, presumably because of immune factors affecting systemic immunity, such as waning antibody titers, impaired T- and B-lymphocyte responses, and the use of immunosuppressive therapies. However, a relationship between the use of local immunosuppressive agents and HPV reactivation and spread has not been previously described, to our knowledge. A 30-year-old woman, 2 years post transplant receiving systemic cyclosporine for cGVHD, was treated with vaginal dilators, topical corticosteroids, and estrogen for vaginal cGVHD. Colposcopy and biopsy for abnormal cytology revealed condylomatous cervicitis. Over the next 4 months, while continuing dilator therapy, linear verrucous lesions developed in the vagina and vulva, and were successfully treated with laser therapy. Use of local immunosuppression and dilators for genital GVHD can enhance spread of HPV infection. Integration of HPV screening and treatment into the care of women with genital cGVHD and development of strategies to manage both conditions simultaneously are warranted.

Successful autologous cord blood transplantation in a child with acquired severe aplastic anemia

Over 400 cases of pediatric SAA occur annually in the United States. A growing number of children with SAA may have had their stem cells harvested through cord blood collection. We describe a nine-yr-old male with SAA treated successfully with an autologous cord blood transplant following immunoablative chemotherapy. With the increasing number of people cryopreserving autologous cord blood, the use of autologous cord blood in the treatment of SAA might be considered as initial therapy. This case serves to discuss approaches to preparative therapy as well as the potential complications in this growing cohort of patients.

Doxorubicin sensitizes human tumor cells to NK cell- and T-cell-mediated killing by augmented TRAIL receptor signaling

Doxorubicin (DOX) is an anthracycline antibiotic that is widely used to treat different types of malignancy. In this study, it was studied whether DOX could be used to render tumor cells susceptible to apoptosis by NK and T cells. Pretreatment with subapoptotic doses of DOX sensitized tumor cell lines of various histotypes to both NK and T cells resulting in a 3.7 to 32.7% increase in lysis (2.5 mean fold increase, p < 0.0001) and a 2.9 to 14.2% increase in lysis (3.0 mean-fold increase, p < 0.05), respectively. The sensitizing effect of the drug was primarily dependent on the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/TRAIL-receptor signaling, but not on Fas-ligand, perforin, NKG2D or DNAM-1. The central role of the TRAIL signaling pathway was further supported by an increased expression of TRAIL-R2 on DOX-treated tumor cells and by downregulation of cellular FLICE inhibitory protein, the inhibitors of death receptor-mediated apoptosis. Compared to untreated cells, pretreatment of tumor cells with DOX showed increased processing and activation of caspase-8 on coculture with NK or T cells. The significance of this treatment strategy was confirmed using a xenogeneic tumor-bearing mouse model. Tumor progression was delayed in mice that received either NK cells (p < 0.05) or T cells (p < 0.0001) following DOX treatment compared to mice receiving either cell type alone. Moreover, combined infusion of both NK and T cells following DOX treatment not only delayed tumor progression but also significantly improved the long-term survival (p < 0.01). Based on these findings, it was proposed that DOX can be used to improve the efficacy of adoptive cell therapy in patients with cancer.

CMV reactivation is associated with a lower incidence of relapse after allo-SCT for CML

Preemptive therapy at CMV reactivation has diminished post-transplant CMV mortality. Furthermore, recent studies suggest a favorable 'virus-versus-leukemia' effect from reactivating CMV, reducing relapse of AML after SCT. We studied the relationship of CMV reactivation with leukemic relapse in 110 patients with CML receiving HLA-identical sibling SCT between 1993 and 2008. Of these, 79 (72%) were in chronic phase, 5 in second chronic phase, 17 in accelerated phase and 9 in blast phase. A total of 97 patients (88%) received a myeloablative conditioning regimen, 97 received 4-log ex vivo T cell-depleted grafts and 13 received T-replete grafts. CMV reactivation before day 100 was observed in 72 patients (65.5%). At a median follow-up of 6.2 years, CMV reactivation < day 100 as a time-dependent covariate was an independent factor associated with decreased relapse. We conclude that CMV reactivation may contribute to a beneficial GVL effect in CML transplant recipients.

Toso, a functional IgM receptor, is regulated by IL-2 in T and NK cells

We find that the cell surface receptor Toso is dramatically downregulated by in vitro stimulation of human T and NK cells with IL-2 in a STAT5-dependent manner. The fact that IL-2 is known to prime NK and T cells for Fas/TNF-mediated activation-induced cell death (AICD) fits nicely with the original and recent descriptions of Toso as an inhibitor of Fas/TNF-induced apoptosis. In support of this possibility, effector memory T cells express markedly lower levels of Toso than those of naive T cells, indicating that activation in vivo correlates with the downregulation of Toso. Moreover, in vitro activation of memory T cells through TCR dramatically downregulates Toso expression compared with that of naive CD4 T cells. However, overexpression of Toso in human NK cells and Jurkat T cells does not inhibit Fas-mediated apoptosis, and, in agreement with other recent reports, Toso clearly functions as an IgM receptor. Unlike CD16, Toso expression by NK cells does not convey cytotoxic potential, but its ligation does trigger intracellular signaling in NK cells. In summary, our data indicate that Toso is a functional IgM receptor that is capable of activating signaling molecules, is regulated by IL-2, and is not inherently an antiapoptotic molecule.

Lymphodepletion is permissive to the development of spontaneous T-cell responses to the self-antigen PR1 early after allogeneic stem cell transplantation and in patients with acute myeloid leukemia undergoing WT1 peptide vaccination following chemotherapy

PR1, an HLA-A*0201 epitope shared by proteinase-3 (PR3) and elastase (ELA2) proteins, is expressed in normal neutrophils and overexpressed in myeloid leukemias. PR1-specific T cells have been linked to graft-versus-leukemia (GVL) effect. We hypothesized that lymphopenia induced by chemo-radiotherapy can enhance weak autoimmune responses to self-antigens such as PR1. We measured PR1-specific responses in 27 patients 30-120 days following allogeneic stem cell transplant (SCT) and correlated these with ELA2 and PR3 expression and minimal residual disease (MRD). Post-SCT 10/13 CML, 6/9 ALL, and 4/5 solid tumor patients had PR1 responses correlating with PR3 and ELA2 expression. At day 180 post-SCT, 8/8 CML patients with PR1 responses were BCR-ABL-negative compared with 2/5 BCR-ABL-positive patients (P = 0.025). In contrast, PR1 responses were detected in 2/4 MRD-negative compared with 4/5 MRD-positive ALL patients (P = 0.76). To assess whether the lymphopenic milieu also exaggerates weak T-cell responses in the autologous setting, we measured spontaneous induction of PR1 responses in 3 AML patients vaccinated with WT1-126 peptide following lymphodepletion. In addition to WT1-specific T cells, we detected PR1-specific T cells in 2 patients during hematopoietic recovery. Our findings suggest that lymphopenia induced by chemo-radiotherapy enhances weak autoimmune responses to self-antigens, which may result in GVL if the leukemia expresses the relevant self-antigen.

Nonmyeloablative stem cell transplantation as immunotherapy for kidney cancer and other metastatic solid tumors

Over the past few decades, great strides have been made to advance the field of allogeneic hematopoietic stem cell transplantation. The donor immune mediated graft-vs-tumor effect that follows the procedure is now widely accepted as the most effective form cancer immunotherapy available for patients with a variety of advanced hematological malignancies. Recognition that a transplanted immune system could cure patients with treatment refractory leukemia led to the development of ;low-intensity' conditioning regimens, which have improved the safety of the procedure and broadened the application of allogeneic immunotherapy to a growing list of neoplastic diseases. Here we discuss the investigational use of allogeneic transplantation as immunotherapy for patients with metastatic, treatment-refractory solid tumors.

Selectively T cell-depleted allografts from HLA-matched sibling donors followed by low-dose posttransplantation immunosuppression to improve transplantation outcome in patients with hematologic malignancies

We evaluated a photodepletion technique to selectively deplete host-reacting T cells from human leukocyte antigen (HLA)-matched sibling stem cell transplantations with the goal of reducing posttransplantation immunosuppression to improve antimalignancy effects postallografting. Donor lymphocytes were stimulated with irradiated expanded recipient T lymphocytes in an ex vivo mixed lymphocyte reaction. Alloactivated T cells preferentially retaining the photosensitizer 4,5-dibromorhodamine 123 (TH9402) were eliminated by exposure to visible light. Twenty-four patients with hematologic malignancies (16 high risk) conditioned with fludarabine, cyclophosphamide, and totalbody irradiation received a CD34-selected stem cell allograft from an HLA-matched sibling along with 5 × 10(6)/kg selectively depleted donor T cells. Low-dose cyclosporine was used for posttransplantation immunosuppression. Eleven patients survived at a median of 30 months. Probabilities (± SEM) for overall and disease-free survival are 39% ± 12% and 30% ± 12%, respectively, whereas grade III-IV acute graft-versus-host disease (aGVHD) was 13% ± 7%. Six patients relapsed, with a relapse probability of 27% ± 10%. These results suggest that selectively photodepleted allografts in matched sibling transplantations followed by low-dose immunosuppression may protect against severe aGVHD but is associated with delayed immune recovery.

Function, adjustment, quality of life and symptoms (FAQS) in allogeneic hematopoietic stem cell transplantation (HSCT) survivors: a study protocol

Background

The population of survivors following allogeneic HSCT continues to increase, and yet their experiences of recovery and long-term survivorship have not been fully characterized. This paper presents a study protocol examining over time the functional status, psychosocial adjustment, health-related quality of life, and symptom experience of survivors who have undergone allogeneic transplantation. The aims of the study are to: 1) explore the patterns of change in these health outcomes during the survivorship phase; 2) characterize subgroups of survivors experiencing adverse outcomes; and 3) examine relationships among outcomes and demographic and clinical factors (such as age, graft-versus-host disease (GVHD), and disease relapse).

Methods

In this longitudinal observational study, adults who survive a minimum of 3 years from date of allogeneic transplantation complete a series of questionnaires annually. Demographic and clinical data are collected along with a series of patient-reported outcome measures, specifically: 1) Medical Outcomes Study SF- 36; 2) Functional Assessment of Chronic Illness Therapy (FACIT) - General, 3) FACIT-Fatigue; 4) FACIT- Spiritual; 5) Psychosocial Adjustment to Illness Scale; 6) Rotterdam Symptom Checklist-Revised; and 7) Pittsburgh Sleep Quality Index.

Conclusions

This study will provide multidimensional patient-reported outcomes data to expand the understanding of the survivorship experience across the trajectory of allogeneic transplantation recovery. There are a number of inherent challenges in recruiting and retaining a diverse and representative sample of long-term transplant survivors. Study results will contribute to an understanding of outcomes experienced by transplant survivors, including those with chronic GVHD, malignant disease relapse, and other late effects following allogeneic transplantation.

Trial Registration

ClinicalTrials.gov: NCT00128960

A pilot study evaluating the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers

This study evaluated the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers. Three cohorts of six subjects received two different doses of plerixafor separated by at least 2 weeks to allow for adequate pharmacodynamic wash-out. The following dosing cohorts were evaluated: 0·24 and 0·32 mg/kg (Cohort 1); 0·32 and 0·40 mg/kg (Cohort 2); and 0·40 and 0·48 mg/kg (Cohort 3). Circulating CD34+ cells were measured 0, 2, 4, 6, 8, 10, 12, 14, 18 and 24 h after each dose. Blood colony-forming units were measured at baseline and 6 h after each dose. Common adverse events were diarrhoea, injection site erythema, perioral numbness, sinus tachycardia, headache, nausea, abdominal distention and injection site pain. No dose limiting toxicities occurred. When higher doses of plerixafor were administered, there was a trend towards higher peak CD34+ counts and CD34+ area under the curves, although these differences did not achieve statistical significance, perhaps due to intra-subject variability. Together, these data show that the higher doses of plerixafor evaluated in this study are reasonably safe and suggest that a larger study should be performed to definitively answer whether increased numbers of CD34+ cell are mobilized with higher doses of plerixafor.

National Institutes of Health Center for Human Immunology Conference, September 2009

Although studies of the laboratory mouse model have laid the groundwork for our rich understanding of immunobiology, they have fallen short in deciphering human disease and providing much needed therapeutic modalities. Indeed, bench-to-bedside approaches have not been a particularly effective means of developing translational research.(1) Recently, a symposium was held at the National Institutes of Health (NIH) entitled "Meeting the Human Immunology Challenge," highlighting the opportunities for the new Intramural NIH Center for Human Immunology, Autoimmunity, and Inflammation (http://www.nhlbi.nih.gov/resources/chi/); among other things it has become clear that a broader definition of the human immune spectrum in health and disease is needed. The human immunology meeting was held in the Clinical Center of the National Institutes of Health, Bethesda, Maryland, on September 3 and 4, 2009.

High-dose continuous infusion beta-lactam antibiotics for the treatment of resistant Pseudomonas aeruginosa infections in immunocompromised patients

OBJECTIVE

To report a case series of high-dose continuous infusion beta-lactam antibiotics for the treatment of resistant Pseudomonas aeruginosa infections.

CASE SUMMARY

Continuous infusion ceftazidime or aztreonam was administered to achieve target drug concentrations at or above the minimum inhibitory concentration, when possible, in 3 patients with P. aeruginosa infections. The maximal calculated target drug concentration was 100 mg/L. In the first patient, with primary immunodeficiency, neutropenia, and aggressive cutaneous T-cell lymphoma/leukemia, continuous infusion ceftazidime (6.5-9.6 g/day) was used to successfully treat multidrug-resistant P. aeruginosa bacteremia. In the second patient, with leukocyte adhesion deficiency type 1, continuous infusion aztreonam (8.4 g/day) was used to successfully treat multidrug-resistant P. aeruginosa wound infections. In the third patient, with severe aplastic anemia, continuous infusion ceftazidime (7-16.8 g/day) was used to treat P. aeruginosa pneumonia and bacteremia. In each patient, bacteremia cleared, infected wounds healed, and pneumonia improved in response to continuous infusion ceftazidime or aztreonam.

DISCUSSION

Treatment strategies for multidrug-resistant P. aeruginosa infections are limited. A novel treatment strategy, when no other options are available, is the continuous infusion of existing beta-lactam antibiotics to maximize their pharmacodynamic activity. High-dose continuous infusion ceftazidime or aztreonam was used for the successful treatment of resistant systemic P. aeruginosa infections in 3 chronically immunocompromised patients.

CONCLUSIONS

Continuous infusion beta-lactam antibiotics are a potentially useful treatment strategy for resistant P. aeruginosa infections in immunocompromised patients.