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Abstract: Adenovirus vaccine vectors derived from rare human serotypes have been shown to be less potent than serotype 5 (Ad5) at inducing immune responses to encoded antigens. To identify highly immunogenic adenovirus vectors, we assessed pro-inflammatory cytokine expression, binding to the CD46 receptor, and immunogenicity. Species D adenoviruses uniquely suppressed pro-inflammatory cytokines and induced high levels of type I interferon. Thus, it was unexpected that a vector derived from a representative serotype, Ad28, induced significantly higher transgene-specific T cell responses than an Ad35 vector. Prime–boost regimens with Ad28, Ad35, Ad14, or Ad5 significantly boosted T cell and antibody responses. The seroprevalence of Ad28 was confirmed to be <10% in the United States. Together, this shows that a rare human serotype-based vector can elicit strong immune responses, which was not predicted by in vitro results. [Copyright &y& Elsevier]

Objective: Nonmyeloablative cytoreduction is used in clinical hematopoietic stem cell gene therapy trials to increase engraftment of gene-modified cells. We utilized an infant rhesus monkey model to identify an optimal dosage of busulfan that results in efficient long-term gene marking with minimal toxicities. Methods: Bone marrow (BM) was harvested, followed by a single 2-hour intravenous infusion of busulfan at escalating dosages of 0 to 160 mg/m2. CD34+ cells were immunoselected from BM, transduced overnight with a simian immunodeficiency virus–based lentiviral vector carrying a nonexpressed marker gene, and injected intravenously 48 hours post–busulfan administration. Pharmacokinetics were assessed, as well as adverse effects and peripheral blood and BM gene marking. Results: Increasing dosages of busulfan resulted in increased area-under-the-curve (AUC) with some variability at each dosage level, suggesting interindividual variation in clearance. Blood chemistries were normal and no adverse effects were observed as a result of busulfan infusion. At 120 and 160 mg/m2, transient neutropenia and thrombocytopenia were noted but not lymphopenia. Over the 6 months of study posttransplantation, a busulfan dosage-related increase in gene marking was observed ranging from undetectable (no busulfan) up to 0.1% gene-containing cells in animals achieving the highest busulfan AUC. This corresponds to a more than 100-fold increase in gene marking over the busulfan dosage range studied. Conclusions: These data indicate that increased gene marking of hematopoietic stem cells can be achieved by escalating busulfan dosages from 40 to 160 mg/m2 without significant toxicity in infant nonhuman primates. [Copyright &y& Elsevier]

Abstract: HIV-1-derived lentiviral vectors have been pseudotyped with various envelope glycoproteins to alter their host range. Previously, we found that envelope glycoproteins derived from the alphavirus Ross River virus (RRV) can pseudotype lentiviral vectors and mediate efficient transduction of a variety of epithelial and fibroblast-derived cell lines. In this study, we have investigated transduction of hematopoietic cells using RRV-pseudotyped vectors encoding the enhanced green fluorescent protein (EGFP). RRV-mediated transduction of human CD34+ cord blood cells and progenitors was very inefficient, even at multiplicities of infection of 100 (0.4% EGFP-positive progenitor colonies). Inefficient transduction was also observed in a variety of hematopoietic cell lines. However, two erythroleukemia-derived cell lines and monocytic cells that were driven to macrophage-like differentiation were moderately transduced. Transduction of hematopoietic cells with a control VSV-G-pseudotyped lentiviral vector was generally efficient, but unexpectedly decreased up to threefold upon stimulation of lymphocytic cell lines or primary murine bone marrow cells. Also, the tested hematopoietic cell lines were essentially nonpermissive for adeno-associated type 2 (AAV) vectors, and this was not affected by lineage, activity, or differentiation. Treatment of permissive 293 cells with proteases revealed that transduction with both the RRV- and the VSV-G-pseudotyped vectors in part depends on the presence of cell surface proteins. These results show a severely restricted ability of RRV glycoproteins to mediate transduction in hematopoietic cells that is likely due to specific receptor requirements that differ from those of VSV-G and AAV. Conversely, transduction with the VSV glycoprotein is affected by cellular activation more than widely believed. Our findings suggest that the envelope glycoproteins and culture conditions employed need to be carefully evaluated for each application. Furthermore, the uniquely restricted host range of RRV-pseudotyped vectors may aid in the design of novel cell-selective transduction strategies. [Copyright &y& Elsevier]

Abstract: A multivariate analysis of 121 dogs conditioned with 200, 100, or 50 cGy of total body irradiation (TBI) followed by hematopoietic stem cell transplantation from matched littermates showed that TBI dose was the only factor examined that was statistically significantly associated with the percentage of donor myeloid engraftment in stable long-term chimeras (P = .008). To understand the direct effects of low-dose irradiation on hematopoietic stem/progenitor cells, nonirradiated and irradiated human CD34+ cells were evaluated for competitive repopulating ability in nonobese diabetic/severe combined immunodeficiency beta2m−/− mice. As expected, the results showed a radiation dose-dependent loss of competitive repopulating ability. Flow cytometric analysis indicated that, within a viable cell gate, there was reduced expression of P-selectin glycoprotein ligand-1 and L selectin on irradiated compared with nonirradiated CD34+ cells; this suggests that irradiated stem/progenitor cells may be compromised in their ability to home to or interact with the marrow microenvironment. However, the CD34+/P-selectin glycoprotein ligand-1 dim cells also showed activation of caspase-3, indicating that they were destined to die. These results suggest that the TBI dose determines the degree of myeloid engraftment by compromising the resident stem/progenitor cell compartment. [Copyright &y& Elsevier]

The efficiency of transduction of both human and non-human primate cells by lentiviral vectors is influenced by interactions with members of the TRIM5α family of cytoplasmic proteins. This has been a particular problem when using HIV-1-derived vectors in rhesus macaque hematopoietic cells, where the vectors are strongly restricted by rhesus TRIM5α, although SIV-derived vectors are not. Current models to explain this variation in restriction postulate that the recruitment of cyclophilin A (CypA) by HIV-1 capsid protects the virus from TRIM5α restriction in human cells, but not in macaque cells. Conversely, although the SIVmac capsid does not bind CypA, it is not significantly restricted by human TRIM5α. We wanted to further investigate the role of the CypA-capsid interaction in the restriction of lentiviral vectors by transducing various cell types with VSV-G-pseudotyped lentiviral vectors expressing the enhanced green fluorescent protein (eGFP) gene and then analyzing gene expression by FACS. As expected, we found that treatment of human embryonic kidney cells (HEK293A) cells with cyclosporine A (CsA), which inhibits the CypA-capsid interaction, resulted in a ∼2-fold drop in transduction with the HIV-1-based vector. Inclusion of either the HIV-2 or SIV nef proteins in the vector did not relieve its sensitivity to CsA. In contrast, transduction with HIV-1 vectors containing certain capsid substitutions within the CypA-binding site (Chatterji et al., JBC;280(48):40293–40300) was not negatively affected by CsA treatment, suggesting that the mutated vectors no longer require CypA for efficient transduction of human cells. These vectors also transduced owl monkey and rhesus macaque kidney cells more efficiently than the wild-type vector. Vectors derived from different SIVmac-strains were found to transduce rhesus macaque cell lines at equal efficiency, but transduction of primary rhesus CD34+ cells with an SIVmac1A11-derived vector (Hanawa et al., Blood;103:4062–4069) was significantly more efficient (30–60 %) than with an SIVmac251-derived vector (4–12%) (Nègre et al., Gene Therapy;7:1613–1623). Experiments in which the SIVmac transfer vectors were crosspackaged with capsids from the other SIVmac strains revealed that this property maps to the transfer vector and not to the packaging construct. CsA treatment increased transduction with SIVmac-derived vectors in both rhesus and owl monkey cell lines and in primary human CD34+ cells, suggesting that the SIVmac capsid is susceptible to restriction in these tissues. In contrast, CsA treatment had no effect on transduction with either HIV-1 or SIVmac-derived vectors in primary rhesus macaque CD34+ cells. Together, these results show differential restriction of lentiviral vectors that varies with the species and cell type transduced. These findings may be relevant for studies using lentiviral gene transfer into non-human primate models.Molecular Therapy (2006) 13, S140–S140; doi: 10.1016/j.ymthe.2006.08.427 [ABSTRACT FROM AUTHOR]

An abstract of the article "Busulfan Dose Escalation to Increase Gene Marking of Hematopoietic Stem Cells by Lentiviral Vectors in Infant Rhesus Monkeys," by Christoph A. Kahl and colleagues is presented.

Molecular biomarkers and primary tumour sidedness guide treatment decisions in metastatic colorectal cancer. Comprehensive molecular profiling aims to identify targetable alterations and measure tumour mutational burden (TMB) to enable precision oncology. FoundationOne® next-generation sequencing identified single-nucleotide variants (SNVs), copy number alterations, high TMB (TMB-H) and high-grade microsatellite instability (MSI-H) in patients treated in the FIRE-3 trial. Data were correlated with objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). Three hundred seventy-three (49.6%) of 752 patients provided material for this analysis. Frequent SNVs included TP53, APC, KRAS , PIK3CA , BRAF , SMAD4 and FBXW7. KRAS, BRAF V600E and SMAD4 mutations were confirmed as prognostic biomarkers by logistic penalised regression for ORR. OS was significantly longer in patients with SMAD4 wild-type (WT) tumours than in those with SMAD4-mutated tumours (hazard ratio = 0.59 [95% confidence interval {CI} = 0.34–1.01], p = 0.05), with a higher probability of ORR [odds ratio, SMAD4 SNV versus WT = 0.32 [95% CI = 0.10–0.98], p = 0.05] when treated with cetuximab. MSI-H (30.0%, p = 0.03) and TMB-H (17.3%, p = 0.003) tumours were enriched by FBXW7 mutations. Numerically lower ORR, OS and PFS were observed in MSI-H tumours. RAS , BRAF V600E and SMAD4 mutations were identified as poor prognostic biomarkers in patients of the FIRE-3 trial, whereas improved outcome was observed for BRAF non-V600E mutation. SMAD4 mutation might provide predictive relevance for cetuximab efficacy. MSI-H tumours showed numerically lower ORR, OS and PFS. • Next-generation sequencing identified additional mutations of KRAS and BRAF. • SMAD4- mutated tumours were associated with lower susceptibility to cetuximab. • BRAF non-V600E–mutated tumours were associated with favourable prognosis and CMS4. • Tumours of the right, transverse and left colon differed in mutational profiles. [ABSTRACT FROM AUTHOR]

Background Combination chemotherapy has shown benefit in the treatment of biliary cancer and further improvements might be achieved by the addition of a biological agent. We report here the effect of chemotherapy with the monoclonal EGFR antibody panitumumab as therapy for KRAS wild-type biliary cancer. Patients and methods Patients with advanced biliary tract cancer were randomised (2:1) to receive cisplatin 25 mg/m 2 and gemcitabine 1000 mg/m 2 on day 1 and day 8/q3w with (arm A) or without panitumumab (arm B; 9 mg/kg BW, i.v q3w). The primary end-point was the evaluation of progression-free survival (PFS) at 6 months. Secondary end-points included objective response rate (ORR), overall survival (OS), and toxicity. In addition, a post hoc assessment of genetic alterations was performed. Finally, we performed a meta-analysis of trials with chemotherapy with and without EGFR antibodies. Results Sixty-two patients were randomised in arm A and 28 patients in arm B. Patients received 7 treatment cycles in median (1–35) with a median treatment duration of 4.7 months (141 days, 8–765). PFS rate at 6 months was 54% in patients treated with cisplatin/gemcitabine and panitumumab but was 73% in patients treated with cisplatin/gemcitabine without antibody, respectively. Secondary end-points were an ORR of 45% in treatment arm A compared with 39% receiving treatment B and a median OS of 12.8 months (arm A) and of 20.1 months (arm B), respectively. In contrast to the p53-status, genetic alterations in IDH1/2 were linked to a high response after chemotherapy and prolonged survival. In accordance with our results, the meta-analysis of 12 trials did not reveal a survival advantage for patients treated with EGFR antibodies compared with chemotherapy alone. Conclusions Panitumumab in combination with chemotherapy does not improve ORR, PFS and OS in patients with KRAS wild-type, advanced biliary cancer. Genetic profiling should be included in CCA trials to identify and validate predictive and prognostic biomarkers. Clinical Trials Number The trial was registered with NCT01320254 . [ABSTRACT FROM AUTHOR]

Background: FIRE-3 compared first-line 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) plus cetuximab with FOLFIRI plus bevacizumab in patients with KRAS exon 2 wild-type metastatic colorectal cancer. The same study also reported an exploratory analysis of a subgroup of patients with tumours that were wild-type at other RAS genes (KRAS and NRAS exons 2-4). We report here efficacy results for the FIRE-3 final RAS (KRAS/NRAS, exons 2-4) wild-type subgroup. Moreover, new metrics of tumour dynamics were explored during a centralised radiological review to investigate how FOLFIRI plus cetuximab conferred overall survival benefit in the absence of differences in investigator-assessed objective responses and progression-free survival.Methods: FIRE-3 was a randomised phase 3 trial comparing FOLFIRI plus cetuximab with FOLFIRI plus bevacizumab in the first-line treatment of patients with KRAS exon 2 wild-type metastatic colorectal cancer. The primary endpoint of the FIRE-3 study was the proportion of patients achieving an objective response according to Response Evaluation Criteria In Solid Tumors (RECIST) 1.0 in the intention-to-treat population. A centralised radiological review of CT scans was done in a post-hoc analysis to assess objective response according to RECIST 1.1, early tumour shrinkage, depth of response, duration of response, and time to response in the final RAS wild-type subgroup. Comparisons between treatment groups with respect to objective response rate and early tumour shrinkage were made using Fisher's exact test (two-sided), while differences in depth of response were investigated with a two-sided Wilcoxon test. This trial is registered at ClinicalTrials.gov, number NCT00433927.Findings: In the final RAS wild-type population (n=400), median overall survival was better in the FOLFIRI plus cetuximab group than the FOLFIRI plus bevacizumab group (33·1 months [95% CI 24·5-39·4] vs 25·0 months [23·0-28·1]; hazard ratio 0·70 [0·54-0·90]; p=0·0059), although investigator-assessed objective response and progression-free survival were comparable between treatment groups. Centralised radiological review of CT-assessable patients (n=330) showed that the proportion of patients achieving an objective response (113 of 157, 72·0% [95% CI 64·3-78·8] vs 97 of 173, 56·1% [48·3-63·6]; p=0·0029), frequency of early tumour shrinkage (107 of 157, 68·2% [60·3-75·4] vs 85 of 173, 49·1% [41·5-56·8]; p=0·0005), and median depth of response (-48·9% [-54·3 to -42·0] vs -32·3% [-38·2 to -29·2]; p<0·0001) were significantly better in extended RAS wild-type patients receiving FOLFIRI plus cetuximab versus those receiving FOLFIRI plus bevacizumab. No differences in duration of response and time to response were observed between treatment groups.Interpretation: This analysis provides a new framework that connects alternative metrics of response to overall survival. Superior response-related outcome parameters, such as early tumour shrinkage and depth of response, obtained by centralised radiological review correlated with the overall survival benefit conferred by FOLFIRI plus cetuximab compared with FOLFIRI plus bevacizumab in the extended RAS wild-type subgroup.Funding: Merck KGaA and Pfizer. [ABSTRACT FROM AUTHOR]

Systemic delivery of a lentiviral vector carrying a therapeutic gene represents a new treatment for monogenic disease. Previously, we have shown that transfer of the adenosine deaminase (ADA) cDNA in vivo rescues the lethal phenotype and reconstitutes immune function in ADA-deficient mice. In order to translate this approach to ADA-deficient severe combined immune deficiency patients, neonatal ADA-deficient mice and newborn rhesus monkeys were treated with species-matched and mismatched vectors and pseudotypes. We compared gene delivery by the HIV-1-based vector to murine γ-retroviral vectors pseudotyped with vesicular stomatitis virus-glycoprotein or murine retroviral envelopes in ADA-deficient mice. The vesicular stomatitis virus-glycoprotein pseudotyped lentiviral vectors had the highest titer and resulted in the highest vector copy number in multiple tissues, particularly liver and lung. In monkeys, HIV-1 or simian immunodeficiency virus vectors resulted in similar biodistribution in most tissues including bone marrow, spleen, liver, and lung. Simian immunodeficiency virus pseudotyped with the gibbon ape leukemia virus envelope produced 10- to 30-fold lower titers than the vesicular stomatitis virus-glycoprotein pseudotype, but had a similar tissue biodistribution and similar copy number in blood cells. The relative copy numbers achieved in mice and monkeys were similar when adjusted to the administered dose per kg. These results suggest that this approach can be scaled-up to clinical levels for treatment of ADA-deficient severe combined immune deficiency subjects with suboptimal hematopoietic stem cell transplantation options. [ABSTRACT FROM AUTHOR]

Summary Background Cetuximab and bevacizumab have both been shown to improve outcomes in patients with metastatic colorectal cancer when added to chemotherapy regimens; however, their comparative effectiveness when partnered with first-line fluorouracil, folinic acid, and irinotecan (FOLFIRI) is unknown. We aimed to compare these agents in patients with KRAS (exon 2) codon 12/13 wild-type metastatic colorectal cancer. Methods In this open-label, randomised, phase 3 trial, we recruited patients aged 18–75 years with stage IV, histologically confirmed colorectal cancer, an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2, an estimated life expectancy of greater than 3 months, and adequate organ function, from centres in Germany and Austria. Patients were centrally randomised by fax (1:1) to FOLFIRI plus cetuximab or FOLFIRI plus bevacizumab (using permuted blocks of randomly varying size), stratified according to ECOG performance status, number of metastatic sites, white blood cell count, and alkaline phosphatase concentration. The primary endpoint was objective response analysed by intention to treat. The study has completed recruitment, but follow-up of participants is ongoing. The trial is registered with ClinicalTrials.gov , number NCT00433927 . Findings Between Jan 23, 2007, and Sept 19, 2012, 592 patients with KRAS exon 2 wild-type tumours were randomly assigned and received treatment (297 in the FOLFIRI plus cetuximab group and 295 in the FOLFIRI plus bevacizumab group). 184 (62·0%, 95% CI 56·2–67·5) patients in the cetuximab group achieved an objective response compared with 171 (58·0%, 52·1–63·7) in the bevacizumab group (odds ratio 1·18, 95% CI 0·85–1·64; p=0·18). Median progression-free survival was 10·0 months (95% CI 8·8–10·8) in the cetuximab group and 10·3 months (9·8–11·3) in the bevacizumab group (hazard ratio [HR] 1·06, 95% CI 0·88–1·26; p=0·55); however, median overall survival was 28·7 months (95% CI 24·0–36·6) in the cetuximab group compared with 25·0 months (22·7–27·6) in the bevacizumab group (HR 0·77, 95% CI 0·62–0·96; p=0·017). Safety profiles were consistent with the known side-effects of the study drugs. The most common grade 3 or worse adverse events in both treatment groups were haematotoxicity (73 [25%] of 297 patients in the cetuximab group vs 62 [21%] of 295 patients in the bevacizumab group), skin reactions (77 [26%] vs six [2%]), and diarrhoea (34 [11%] vs 40 [14%]). Interpretation Although the proportion of patients who achieved an objective response did not significantly differ between the FOLFIRI plus cetuximab and FOLFIRI plus bevacizumab groups, the association with longer overall survival suggests that FOLFIRI plus cetuximab could be the preferred first-line regimen for patients with KRAS exon 2 wild-type metastatic colorectal cancer. Funding Merck KGaA. [ABSTRACT FROM AUTHOR]

Immune responses to transgene products may lead to rejection of transduced cells, limiting successful gene therapy for genetic diseases. While moderate dosages of chemotherapeutic agents such as busulfan may increase hematopoietic stem cells (HSC) engraftment, they are not immune suppressive and do not abrogate immune responses to transgene products. Studies focused on nonmyeloablative conditioning with busulfan ± fludarabine in a clinically relevant monkey model to induce immune suppression to allow cells expressing a foreign transgene product to persist. Bone marrow CD34+ HSC were transduced in two equal fractions using simian immunodeficiency virus (SIV)-based lentiviral vectors carrying a nonexpressed DNA sequence tag (NoN) and the green fluorescent protein (GFP) reporter gene. Post-transplant there was no evidence of elimination of cells containing the potentially immunogenic GFP gene; several recipients had stable persistence of cells, and no differences were detected with fludarabine, which was rapidly cleared. Antibodies and cellular immune responses to GFP developed in recipients with the highest levels of GFP-marked cells, although these cells were not eliminated. These studies establish a clinically relevant pediatric primate model to assess the effects of conditioning regimens on the engraftment of transduced HSC and the immune responses to cells expressing a foreign gene product. [ABSTRACT FROM AUTHOR]

Abstract: Patients with neutropenia lasting for more than 10d, who develop fever and pulmonary infiltrates, are at risk of treatment failure under conventional broad-spectrum antibacterial therapy. Filamentous fungi are predominant causes of failure, however, multi-resistant gram-negative rods such as Pseudomonas aeruginosa or Stenotrophomonas maltophilia may be involved. Prompt addition of mould-active systemic antifungal therapy, facilitated by early thoracic computed tomography, improves clinical outcome. Non-culture-based diagnostic procedures to detect circulating antigens such as galactomannan or 1,3-beta-d-glucan, or PCR techniques to amplify circulating fungal DNA from blood, bronchoalveolar lavage or tissue specimens, may facilitate the diagnosis of invasive pulmonary aspergillosis. CT-guided bronchoalveolar lavage is useful in order to identify causative microorganisms such as multidrug-resistant bacteria, filamentous fungi or Pneumocystis jiroveci. For pre-emptive antifungal treatment, voriconazole or liposomal amphotericin B is preferred. In patients given broad-spectrum azoles for antifungal prophylaxis, non-azole antifungals or antifungal combinations might become first choice in this setting. Antifungal treatment should be continued for at least 14 d before non-response and treatment modification are considered. Microbial isolates from blood cultures, bronchoalveolar lavage or respiratory secretions must be critically interpreted with respect to their aetiological relevance for pulmonary infiltrates. [Copyright &y& Elsevier]