Search

Relapse is a major problem in acute myeloid leukemia (AML) and adversely impacts survival.\ud In this phase II study, we investigated the effect of vaccination with dendritic cells (DCs)\ud electroporated with Wilms’ tumor 1 (WT1) mRNA as post-remission treatment in 30 AML\ud patients at very high risk of relapse. There was a demonstrable anti-leukemic response in 13\ud patients. Nine patients achieved molecular remission as demonstrated by normalization\ud of WT1 transcript levels, 5 of which are sustained after a median follow-up of 109.4 months.\ud Disease stabilization was achieved in 4 other patients. Five-year overall survival (OS) was\ud higher in responders than in non-responders (53.8% vs. 25.0%; P=0.01). In patients\ud receiving DCs in first complete remission (CR1), there was a vaccine-induced relapse\ud reduction rate of 25% and the 5-year relapse-free survival was higher in responders than in\ud non-responders (50% vs. 7.7%; P65 years who received DCs\ud in CR1, 5-year OS was 69.2% and 30.8% respectively, as compared to 51.7% and 18% in\ud the Swedish Acute Leukemia Registry (SALR). Long-term clinical response was correlated\ud with increased circulating frequencies of poly-epitope WT1-specific CD8+ T-cells. Long-term\ud OS was correlated with interferon-γ+ and tumor necrosis factor-α+ WT1-specific responses in delayed type hypersensitivity-infiltrating CD8+ T-lymphocytes. In conclusion, vaccination of\ud AML patients with WT1 mRNA-electroporated DCs can be an effective strategy to prevent or\ud delay relapse after standard chemotherapy, translating into improved OS rates, which are\ud correlated with the induction of WT1-specific CD8+ T-cell response. This trial was registered\ud at www.clinicaltrials.gov as #NCT00965224.

Key Clinical Message The possibility of hemophagocytic lymphohistiocytosis should always be kept in mind when examining/treating a patient with fever of unknown origin and sepsis‐like symptoms. Early diagnosis leading to prompt initiation of immunosuppressive therapy as well as aggressive supportive care, including correction of coagulation abnormalities and treatment of opportunistic infections, can decrease mortality.

Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary immune response. We studied the effects of frequent exposure to viral infectious challenges on immunity. Furthermore, we assessed whether repetitive exposures to varicella-zoster virus (VZV) elicited persistently high immune responses. Blood samples from 11 pediatricians and matched controls were assessed at 3 time points and 1 time point, respectively. Besides the assessment of general immunity by means of measuring T-cell subset percentages, antibody titers and gamma interferon (IFN-γ)/interleukin 2 (IL-2)-producing T-cell percentages against adenovirus type 5 (AdV-5), cytomegalovirus (CMV), tetanus toxin (TT), and VZV were determined. Pediatricians had lower levels of circulating CD4+-naive T cells and showed boosting of CD8+effector memory T cells. Although no effect on humoral immunity was seen, repetitive exposures to VZV induced persistently higher percentages of IFN-γ-positive T cells against all VZV antigens tested (VZV glycoprotein E [gE], VZV intermediate-early protein 62 [IE62], and VZV IE63) than in controls. T cells directed against latency-associated VZV IE63 benefitted the most from natural exogenous boosting. Although no differences in cellular or humoral immunity were found between the pediatricians and controls for AdV-5 or TT, we did find larger immune responses against CMV antigens in pediatricians. Despite the high infectious burden, we detected a robust and diverse immune system in pediatricians. Repetitive exposures to VZV have been shown to induce a stable increased level of VZV-specific cellular but not humoral immunity. Based on our observations, VZV IE63 can be considered a candidate for a zoster vaccine.

Longitudinal clinical or experimental immunological studies warrant the use of cryopreserved samples for flow cytometric phenotyping. Most notably CD62L + and CD25 +Foxp3 + counts were shown to be reduced by past studies. Here we are the first to compare the effects of cryopreservation on cell type calculations performed on a longitudinal dataset. We first compared lymphocyte subpopulation counts from fresh samples with those from samples frozen for either 5 or 6 months coming from 9 individuals. This way, we found that the cell counts obtained after basic lymphocyte differentiation in CD3 + CD4 +, CD3 + CD8 +, CD3 − CD19 + and CD3 − CD56 + were relatively robust for cryopreservation. However, when further subtyping CD4 + and CD8 + cells, we only found CCR7 and CD45RA to have a relation between fresh and cryopreserved counts, but we could not conclude the same for CD62L. Also, CD4 + CD25 + Foxp3 + were shown to be approximately 0.5 times less counted after cryopreservation. Next, we performed basic longitudinal calculations for which we either subtracted the cell counts at time 1 from the cell counts at time 2 or calculated the ratio between the cell counts at time 2 and time 1, for both fresh and cryopreserved samples. This way, we found that the use of absolute cell counts supported a good one-to-one relation between fresh and cryopreserved counts for all markers except CD62L and CD4 + CD25 + Foxp3 +. In conclusion, we found no support for the use of CD62L and CD4 + CD25 + Foxp3 + as markers for calculations on flow cytometric counts from cryopreserved longitudinal datasets. However, all other basic lymphocyte markers proved to be relatively robust if absolute counts were used.

Tumor recurrence and lack of tumor control are major problems in cancer treatment. In order to control malignant disease, we performed phase I/II dendritic cell (DC) vaccination studies in an adjuvant setting in 30 patients with acute myeloid leukemia (AML) and in 36 patients with solid tumors. Following chemotherapy, the patients underwent leukapheresis; CD14+ monocytes were isolated, cultured into clinical-grade mature DC, electroporated with mRNA encoding the Wilms' tumor protein WT1 and injected intradermally (Van Tendeloo et al. PNAS 2010;107:13824-9). No major DC-related systemic toxicity was observed. DC vaccination as a post-remission treatment was evaluated in 30 AML patients following chemotherapy; 27 patients were in complete remission (CR) but at very high risk of relapse and 3 in partial remission (PR). WT1 mRNA levels in blood and marrow were followed as a measure of residual disease. Clinical and molecular response, as determined by normalization of WT1 transcript levels in blood and/or marrow, occurred in 8/23 patients who had increased levels of that marker at the start of DC vaccination. Of these 8 responding patients, 5 are still in complete and molecular remission, all of them now more than 5 years after diagnosis and most probably cured; 1 of those 5 patients was in PR following chemotherapy and was brought into complete and molecular remission by the DC vaccination only. There was a possible effect of DC vaccination in 6 additional patients: 3 with stable disease, some of it late; and 3 at high risk of relapse but without increased WT1 mRNA levels before DC vaccination: 1 patient with erythroleukemia and 2 patients with initial leucocytosis >20,000/µL have remained in CR, now at respectively 57, 52 and 45 months post-diagnosis. Overall 8/30 patients have not relapsed yet, with a median follow-up from diagnosis and start of DC vaccination of respectively 70 months (range 45 - 92 months) and 63 months (range 39-90 months). Delayed type hypersensitivity (DTH) testing showed immunoreactivity to the DC vaccine in all patients tested. WT1 epitope tetramer+ CD8+ T-cells were evaluated in 13 HLA-A2+ patients: an increase following DC vaccination in tetramer+ T-cells for at least 2/4 epitopes tested was only observed in patients with long-standing CR. Ten patients with unresectable, epithelial-type malignant pleural mesothelioma and non-progressive disease after platinum/pemetrexed-based chemotherapy received DC vaccination. Evaluation of response according to RECIST criteria showed 7 patients with stable disease and 3 with progressive disease. DTH testing showed vaccine-elicited immunity in 9/10 patients. Median overall survival (OS) from start of chemotherapy was 32 months; this compares with an OS of 22 months reported in the literature for a similar subgroup of patients treated with chemotherapy only (Hillerdal et al. J Thorac Oncol 2008). Twenty-six patients with other advanced and pre-treated cancers also underwent DC vaccination (13 with breast cancer (12 with metastatic disease), 5 with glioblastoma multiforme (GBM), 1 with brain stem astrocytoma and 1 each with metastatic melanoma, Ewing sarcoma, esophageal, colon, pancreatic, renal cell and ovarian cancer). Significant DTH responses were recorded in all patients. At a median follow-up from start of DC vaccination of 23.3 months, 8/26 patients (31%) are still alive and median OS was 23.5 months. Evaluation of response showed 3 patients with PR (1 brain stem astrocytoma, 1 GBM and 1 breast cancer) and 1 patient with CR (1 GBM). In the breast cancer patient subgroup, 5/13 patients are still alive (38%) and median OS was 33.5 months after start of DC vaccination; this compares with OS data from the literature of 21.7 months after diagnosis (Kiely et al. J Clin Oncol 2011;29:456-63). In the GBM (n=5) patient subgroup, 1/5 patients is alive in CR 26 months and median OS was 14.7 months after start of DC vaccination; this compares with OS data from the literature of 14.6 months after diagnosis (Stupp et al. N Engl J Med 2005;352:987-96). In conclusion, WT1-targeted DC vaccination is feasible, safe and immunogenic in cancer patients. In AML, metastatic breast cancer and malignant glioma, there is evidence of objective response. In addition, OS data in solid tumors compare favorably with the best data reported so far for similar cohorts of patients, suggesting that adjuvant WT1/DC-based immunotherapy provides a clinical benefit to these patients. Disclosures Off Label Use: Dendritic cells as immunotherapy.

Multiple myeloma (MM) is a B-cell malignancy characterized by the expansion of malignant plasma cells within the bone marrow. Previous studies that have examined the Ig VH genes of IgG and IgA MMs have shown the presence of somatic mutations, suggesting that in these cases, the myeloma precursor cell passed through the phase of antigenic selection within the germinal center but is no longer exposed to the somatic mutation process. However, no information about this matter is available in the rare IgD and IgM MM variants. Therefore, we have analyzed the Ig VH genes of three IgD, one IgM, and one biclonal (IgG and IgM) MM for the presence of somatic mutations. Our study demonstrates that all of these myeloma clones have accumulated a high number of somatic mutations within their Ig VH genes but show no intraclonal variation. Moreover, proof that the clone sustained a strong antigenic selection pressure could be provided in three cases (one IgD and two IgMs). Therefore, this study strongly implies that IgD and IgM MMs emerge from a postgerminal center preswitched B cell that is no longer exposed to the somatic mutation process or able to undergo further isotype switching in vivo.

Relapse remains a major problem in acute myeloid leukemia (AML) and has an important impact on survival, especially in the majority of older patients who cannot undergo allogeneic hematopoietic stem cell transplantation. In a phase II study, we investigated the impact on relapse of dendritic cell (DC) vaccination as a post-remission treatment in 29 AML patients; 26 patients were in complete remission and 3 in partial remission following chemotherapy. DC were derived from blood monocytes, electroporated with mRNA encoding the Wilms' tumor 1 protein (WT1) and administered via the intradermal route. Three different WT1 constructs were used to generate mRNA by in vitro transcription: 'construct 1' encoding full-length WT1, 'construct 2' with a Sig-DC-LAMP major histocompatibility complex (MHC) class II-skewing signal and a deletion of the WT1 nuclear localization signal and 'construct 3', a codon-optimized version of construct 2. WT1 mRNA levels in blood and marrow were followed as a measure of minimal residual disease. DC electroporated with mRNA derived from constructs 1, 2 and 3 were used to vaccinate respectively 13, 6 and 10 AML patients at very high risk of relapse. In those 3 groups, clinical and molecular response, as determined by normalization of WT1 transcript levels in blood and/or marrow, occurred in respectively 7/13, 1/4 and 0/6 patients who had increased levels of that marker at the start of DC vaccination. Of these 8 responding patients, 3 relapsed and died; the other 5 are still in complete remission, 4 of them now more than 5 years after diagnosis and most probably cured; 1 of those 4 patients was in partial remission following chemotherapy and was brought into complete and molecular remission by the DC vaccination only. All 15 patients who did not normalize WT1 mRNA levels following DC vaccination relapsed and/or died. There was a possible effect of DC vaccination in 6 additional patients: 3 with stable disease, some of it late; and 3 at high risk of relapse but without increased WT1 mRNA levels before DC vaccination: 1 patient with erythroleukemia and 2 patients with initial leucocytosis > 20,000/µL have remained in complete remission, now at respectively 46, 42 and 35 months post-diagnosis. Overall 8/29 patients have not relapsed yet, with a median follow-up from diagnosis and start of DC vaccination of respectively 60 months (range 35 - 84 months) and 53 months (range 27-78 months). Delayed type hypersensitivity (DTH) testing showed immunoreactivity to the DC vaccine components in all patients tested. There was also evidence of natural killer (NK) cell activation following DC vaccination. WT1 epitope tetramer+ CD8+ T-cells were evaluated in 13 HLA-A2+ patients: an increase following DC vaccination in tetramer+ T-cells for at least 2/4 epitopes tested was only observed in patients with long-standing complete remission. In conclusion, DC vaccination had a demonstrable antileukemic effect in 8/29 AML patients and a possible effect in another 6. Contrary to expectations, the WT1 constructs with MHC class II-skewing signal did not seem to have superior activity over the full-length WT1 construct without that signal. Vaccination with WT1 mRNA-transfected DC is emerging as a non-toxic strategy to prevent or delay relapse in AML. Disclosures: Off Label Use: Dendritic cell vaccination.

Clinical and scientific work routinely relies on antecubital venipunctures for hematological, immunological or other analyses on blood. This study tested the hypothesis that antecubital veins can be considered to be a good proxy for other sampling sites. Using a hematocytometer and a flow cytometer, we analyzed the cell counts from samples coming from the radial artery, the dorsal hand veins and the antecubital veins from 18 volunteers. Most surprisingly, we identified the greatest difference not to exist between arterial and venous circulation, but between the distal (radial artery & dorsal hand veins) and proximal (antecubital veins) sampling sites. Naive T cells had a higher cell count distally compared to proximally and the reverse was true for effector memory T cells. Despite these differences there were high correlations between the different sampling sites, which partially supports our initial hypothesis. Our findings are crucial for the future design and interpretation of immunological research, and for clinical practice. Furthermore, our results suggest a role for interval lymph nodes in the trafficking of lymphocytes. The authors thank the University of Antwerp for the financial support received. B.O., D. P. and E. S. thank the Research Foundation Flanders (FWO) for the financial support they have received. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

N-Methylepinephrine was analysed in human urine using a high-performance liquid chromatographic catecholamine assay. The identity of the compound was confirmed by gas chromatography-mass spectrometry. The excretion of N-methylepinephrine is slightly less than that of epinephrine: excretion values were in the range 2–65 nmol per 24 h (0.4–13 μg per 24 h) in 150 hypertensive patients. In addition to increased epinephrine excretion, increased urinary excretion of N-methylepinephrine was found in three out of five patients with histologically proven pheochromocytoma.

N-Methylepinephrine was analysed in human urine using a high-performance liquid chromatographic catecholamine assay. The identity of the compound was confirmed by gas chromatography-mass spectrometry. The excretion of N-methylepinephrine is slightly less than that of epinephrine: excretion values were in the range 2-65 nmol per 24 h (0.4-13 micrograms per 24 h) in 150 hypertensive patients. In addition to increased epinephrine excretion, increased urinary excretion of N-methylepinephrine was found in three out of five patients with histologically proven pheochromocytoma

A procedure is described for the concurrent assay of free norepinephrine, epinephrine, dopamine, vanillylmandelic acid and homovanillic acid in physiological fluids using high-performance liquid chromatography with electrochemical detection. The column packing is an octadecyl-bonded silica. A single mobile phase containing 1-octanesulphonate is used for the assay of catecholamines and for the assay of the acidic metabolites. An efficient sample preparation scheme is presented for the isolation of the catecholamines and their acidic metabolites from the same sample aliquot. Catecholamines are extracted by ion exchange on small columns and adsorption on alumina, using dihydroxybenzylamine as an internal standard. Vanillylmandelic acid and homovanillic acid are recovered from the combined loading and washing effluents of the ion-exchange column by a solvent extraction procedure. Recovery of catecholamines averages 67%. The limit of detection for individual catecholamines is ca. 30 pg. Recoveries of vanillylmandelic acid and homovanillic acid average 77% and 87%, respectively. The use of the same mobile phase for the concurrent assay of catecholamines and their acidic metabolites considerably increases the throughput of samples in the chromatographic system by eliminating the time-consuming column-equilibration periods.

We describe five cases of severe alpha 1-antitrypsin (AAT) deficiency to illustrate the importance of visual inspection of electrophoretic patterns of serum proteins. In four patients the diagnosis of AAT deficiency was clinically unsuspected; in the other patient, the electrophoretic pattern was the first clue to confirm the diagnosis. Densitometric scanning of these patterns invariably overestimated the concentration of alpha 1-globulin. By visually inspecting electrophoretic strips instead of relying on densitometry, clinical chemists can help detect AAT deficiency earlier.

We describe five cases of severe alfa1-antitrypsin (AAT) deficiency to illustrate the importance of visual inspection of electrophoretic patterns of serum proteins. In four patients the diagnosis of AAT deficiency was clinically unsuspected; in the other patient, the electrophoretic pattern was the first clue to confirm the diagnosis. Densitometric scanning of these patterns invariably overestimated the concentration of alfa1-globulin. By visually inspecting electrophoretic strips instead of relying on densitometry, clinical chemists can help detect AAT deficiency earlier.