Modified Glasgow prognostic score (mGPS) is correlated with sarcopenia and dominates the prognostic role of baseline body composition parameters in advanced gastric and esophagogastric junction cancer patients undergoing first-line treatment from the phase III EXPAND trial.

BACKGROUND: Sarcopenia represents an established adverse prognostic factor in cancer patients. Consequently, different means to counteract sarcopenia have been proposed to improve cancer treatment. Computed tomography (CT)-based measurements, also labor intensive, are well validated for the analysis of sarcopenia. As inflammation plays a key role in the development of sarcopenia, we here studied the role of the modified Glasgow prognostic score (mGPS), consisting of inflammation parameters plasma C-reactive protein (CRP) and albumin, to predicting sarcopenia and adipose tissue-related body composition (BC) parameters at baseline and their changes during treatment and to analyze its prognostic role in conjunction with BC parameters. PATIENTS AND METHODS: CT measurements of BC parameters were carried out at baseline and week 12 in patients with advanced gastric or esophagogastric junction cancer from the phase III EXPAND trial, undergoing first-line platinum-fluoropyrimidine chemotherapy. mGPS was calculated from baseline CRP and albumin plasma levels. Pearson correlation and Cox regression analyses were carried out. RESULTS: mGPS is strongly prognostic for overall survival (OS). Baseline mGPS is significantly correlated with baseline mean muscle attenuation (MA; P < 0.0001). Baseline mGPS did not predict a decline in muscle or adipose tissue parameters during 12 weeks of treatment and a decline in muscle or adipose tissue parameters was not prognostic for OS. MA lost its prognostic role for OS when mGPS or CRP was entered into the Cox models. Eastern Cooperative Oncology Group performance status together with CRP or mGPS remained the sole baseline prognostic factors for OS. CONCLUSIONS: Our findings support a model where tumor-mediated inflammatory response represents a strong prognostic factor, which is causally related to sarcopenia, but with no direct causal path from sarcopenia to survival. Therefore, therapeutic targeting of systemic inflammation should be further explored as a promising strategy to improve both sarcopenia and the efficacy and tolerability of cancer treatment.

Capsid Engineering Overcomes Barriers Toward Adeno-Associated Virus Vector-Mediated Transduction of Endothelial Cells.

Endothelial cells (EC) are targets in gene therapy and regenerative medicine, but they are inefficiently transduced with adeno-associated virus (AAV) vectors of various serotypes. To identify barriers hampering efficient transduction and to develop an optimized AAV variant for EC transduction, we screened an AAV serotype 2-based peptide display library on primary human macrovascular EC. Using a new high-throughput selection and monitoring protocol, we identified a capsid variant, AAV-VEC, which outperformed the parental serotype as well as first-generation targeting vectors in EC transduction. AAV vector uptake was improved, resulting in significantly higher transgene expression levels from single-stranded vector genomes detectable within a few hours post-transduction. Notably, AAV-VEC transduced not only proliferating EC but also quiescent EC, although higher particle-per-cell ratios had to be applied. Also, induced pluripotent stem cell-derived endothelial progenitor cells, a novel tool in regenerative medicine and gene therapy, were highly susceptible toward AAV-VEC transduction. Thus, overcoming barriers by capsid engineering significantly expands the AAV tool kit for a wide range of applications targeting EC.

Direct comparison between in vivo and in vitro microsized particle phagocytosis assays in Drosophila melanogaster.

The effects of micro and nanoparticles on the innate immune system have been widely investigated and a general lack of agreement between in vivo and in vitro assays has been observed. In order to determine the origin of these discrepancies, there is a need for comparing the results of in vivo and in vitro phagocytosis assays obtained using the same particles and same immune cells. Here, we establish an in vivo polystyrene microsized particle phagocytosis assay in Drosophila melanogaster and compare it with an in vitro assay consisting of exposing the same immune cells in culture to the same particles. The distribution of number of phagocytized beads per cell was shifted to lower numbers of beads per cell in the case of the in vitro assay compared to the in vivo assay, which we suggest is partly due to a reduced amount of membrane available in cultured cells.

A combination of low-dose bevacizumab and imatinib enhances vascular normalisation without inducing extracellular matrix deposition.

BACKGROUND: Vascular endothelial growth factor (VEGF)-targeting drugs normalise the tumour vasculature and improve access for chemotherapy. However, excessive VEGF inhibition fails to improve clinical outcome, and successive treatment cycles lead to incremental extracellular matrix (ECM) deposition, which limits perfusion and drug delivery. We show here, that low-dose VEGF inhibition augmented with PDGF-R inhibition leads to superior vascular normalisation without incremental ECM deposition thus maintaining access for therapy. METHODS: Collagen IV expression was analysed in response to VEGF inhibition in liver metastasis of colorectal cancer (CRC) patients, in syngeneic (Panc02) and xenograft tumours of human colorectal cancer cells (LS174T). The xenograft tumours were treated with low (0.5 mg kg-1 body weight) or high (5 mg kg-1 body weight) doses of the anti-VEGF antibody bevacizumab with or without the tyrosine kinase inhibitor imatinib. Changes in tumour growth, and vascular parameters, including microvessel density, pericyte coverage, leakiness, hypoxia, perfusion, fraction of vessels with an open lumen, and type IV collagen deposition were compared. RESULTS: ECM deposition was increased after standard VEGF inhibition in patients and tumour models. In contrast, treatment with low-dose bevacizumab and imatinib produced similar growth inhibition without inducing detrimental collagen IV deposition, leading to superior vascular normalisation, reduced leakiness, improved oxygenation, more open vessels that permit perfusion and access for therapy. CONCLUSIONS: Low-dose bevacizumab augmented by imatinib selects a mature, highly normalised and well perfused tumour vasculature without inducing incremental ECM deposition that normally limits the effectiveness of VEGF targeting drugs.

Treatment with Antiangiogenic Drugs in Multiple Lines in Patients with Metastatic Colorectal Cancer: Meta-Analysis of Randomized Trials.

Background. In metastatic colorectal cancer (mCRC), continuing antiangiogenic drugs beyond progression might provide clinical benefit. We synthesized the available evidence in a meta-analysis. Patients and Methods. We conducted a meta-analysis of studies investigating the use of antiangiogenic drugs beyond progression. Eligible studies were randomized phase II/III trials. Primary endpoints were overall survival (OS) and progression-free survival (PFS). Secondary endpoints were the impact of continuing antiangiogenic drugs (i) in subgroups, (ii) in different types of compounds targeting the VEGF-axis (monoclonal antibodies versus tyrosine kinase inhibitors), and (iii) on remission rates and prevention of progression. Results. Eight studies (3,668 patients) were included. Continuing antiangiogenic treatment beyond progression significantly improved PFS (HR 0.64; 95%-CI, 0.55-0.75) and OS (HR 0.83; 95%-CI, 0.76-0.89). PFS was significantly improved in all subgroups with comparable HR. OS was improved in all subgroups stratified by age, gender, and ECOG status. The rate of patients achieving at least stable disease was improved with an OR of 2.25 (95%-CI, 1.41-3.58). Conclusions. This analysis shows a significant PFS and OS benefit as well as a benefit regarding disease stabilization when using antiangiogenic drugs beyond progression in mCRC. Future studies should focus on the optimal sequence of administering antiangiogenic drugs.

Inhibitors of Angiogenesis.

Angiogenesis plays a pivotal role in malignant, ischemic, inflammatory, infectious and immune disorders. The increasing molecular understanding of angiogenic processes fostered the development of strategies to induce or inhibit angiogenesis for therapeutic purposes. Here, we focus on anti-angiogenic therapies, which represent a standard of care in the treatment of different cancer types and in neovascular age-related macular degeneration. Specifically, strategies related to the blockade of angiogenic proteins and receptors will be outlined covering both preclinical and clinical aspects. Finally, examples of gene therapy based anti-angiogenic approaches are presented.

Dual targeting of Angiopoetin-2 and VEGF potentiates effective vascular normalisation without inducing empty basement membrane sleeves in xenograft tumours.

BACKGROUND: Effective vascular normalisation following vascular endothelial growth factor (VEGF) inhibition is associated with endothelial cell regression leaving empty basement membrane sleeves (BMS). These long-lived BMS permit the rapid regrowth of tumour vasculature upon treatment cessation and promote resistance to VEGF-targeting drugs. Previous attempts at removing BMS have failed. Angiopoietin-2 (Ang2) is a vascular destabilizing factor that antagonises normalisation. We hypothesised that Ang2 inhibition could permit vascular normalisation at significantly reduced doses of VEGF inhibition, avoiding excessive vessel regression and the formation of empty BMS. METHODS: Mice xenografted with human colorectal cancer cells (LS174T) were treated with low (0.5 mg kg(-1)) or high (5 mg kg(-1)) doses of the VEGF-targeting antibody bevacizumab with or without an Ang2 blocking peptibody L1-10. Tumour growth, BMS formation and normalisation parameters were examined including vessel density, pericyte coverage, adherence junctions, leakiness, perfusion, hypoxia and proliferation. RESULTS: Dual targeting of VEGF and Ang2 achieved effective normalisation at only one-tenth of the dose required with bevacizumab alone. Pericyte coverage, vascular integrity, adherence junctions and perfusion as prerequisites for improved access of chemotherapy were improved without inducing empty BMS that facilitate rapid vascular regrowth. CONCLUSIONS: Dual targeting of VEGF and Ang2 can potentiate the effectiveness of VEGF inhibitors and avoid the formation of empty BMS.

[Neoadjuvant chemotherapy or primary surgery for colorectal liver metastases. Pro adjuvant chemotherapy]. / Neoadjuvante Chemotherapie oder primäre Chirurgie bei kolorektalen Lebermetastasen. Pro neoadjuvante Chemotherapie.

Medicinal treatment of colorectal cancer liver metastases has undergone significant developments in the past two decades. Cytotoxic treatment regimens have demonstrated greater efficacy and contributed to a significant improvement in survival. Perioperative therapy with FOLFOX has demonstrated progression-free survival benefits in resectable colorectal liver metastases in a prospective randomized controlled trial. The safety of perioperative chemotherapy was found to be acceptable and only a few patients showed initial progression. In general, preoperative chemotherapy should not extend beyond 3-4 months to avoid chemotherapy-associated liver damage. For patients with borderline resectable metastases, a response to chemotherapy can establish secondary resectability. Combinations of cytotoxic drugs are adequate in this situation. The addition of bevacizumab or anti-epidermal growth factor receptor (EGFR) antibodies for tumors without RAS mutations are reasonable choices for a better response and improved survival outcome. It is crucial that all treatment decisions for systemic colorectal liver metastases include correct definitions of treatment goals and endpoints and are derived based on appropriate multidisciplinary considerations.

Phase I/II trial of capecitabine and oxaliplatin in combination with bevacizumab and imatinib in patients with metastatic colorectal cancer: AIO KRK 0205.

BACKGROUND: Combined inhibition of platelet-derived growth factor receptor beta signalling and vascular endothelial growth factor promotes vascular normalisation in preclinical models and may lead to increased delivery of chemotherapy to tumour tissue. This phase I/II trial assessed the safety and efficacy of capecitabine plus oxaliplatin (XELOX) plus bevacizumab and imatinib in the first-line treatment of patients with metastatic colorectal cancer. METHODS: Two dose levels (I/II) were defined: capecitabine 850/1000 mg m(-2) twice daily on days 1-14; oxaliplatin 100/130 mg m(-2) on day 1; bevacizumab 7.5 mg kg(-1) on day 1; imatinib 300 mg day(-1) on days 1-21 every 21 days. The primary study endpoint was safety. The phase II secondary endpoint was 6-month progression-free survival (PFS). RESULTS: Dose level I was chosen for phase II testing because, even though further dose escalation was permitted by the protocol, gastrointestinal toxicities were considered to be clinically significant. A total of 49 patients were evaluated. The 6-month PFS rate was 76%, median PFS was 10.6 months and median overall survival was 23.2 months. Haematological toxicities were generally mild. Sensory neuropathy and diarrhoea were the most common grade 3 toxicities. CONCLUSION: The combination of XELOX with bevacizumab and imatinib is tolerable and has promising efficacy.

Regorafenib in combination with FOLFOX or FOLFIRI as first- or second-line treatment of colorectal cancer: results of a multicenter, phase Ib study.

BACKGROUND: Metastatic colorectal cancer (mCRC) is commonly treated with 5-fluorouracil, folinic acid, and oxaliplatin or irinotecan. The multitargeted kinase inhibitor, regorafenib, was combined with chemotherapy as first- or second-line treatment of mCRC to assess safety and pharmacokinetics (primary objectives) and tumor response (secondary objective). PATIENTS AND METHODS: Forty-five patients were treated every 2 weeks with 5-fluorouracil 400 mg/m(2) bolus then 2400 mg/m(2) over 46 h, folinic acid 400 mg/m(2), and either oxaliplatin 85 mg/m(2) or irinotecan 180 mg/m(2). On days 4-10, patients received regorafenib 160 mg orally once daily. RESULTS: The median duration of treatment was 108 (range 2-345 days). Treatment was stopped for adverse events or death (17 patients), disease progression (11 patients), and consent withdrawal or investigator decision (11 patients). Six patients remained on regorafenib at data cutoff (two without chemotherapy). Drug-related adverse events occurred in 44 patients [grade ≥ 3 in 32 patients: mostly neutropenia (17 patients) and leukopenia, hand-foot skin reaction, and hypophosphatemia (four patients each)]. Thirty-three patients achieved disease control (partial response or stable disease) for a median of 126 (range 42-281 days). CONCLUSION: Regorafenib had acceptable tolerability in combination with chemotherapy, with increased exposure of irinotecan and SN-38 but no significant effect on 5-fluorouracil or oxaliplatin pharmacokinetics.

[Recent results of research on cancer of the colon, gastric cancer, sarcoma and bronchial carcinoma]. / Neue Forschungsergebnisse zum Kolonkarzinom, Magenkarzinom, Sarkomen und Bronchialkarzinom.

In patients up to 70 years of age with colon carcinoma stage III adjuvant chemotherapy with infusions of fluorouracil (5-FU) or oral capecitabine combined with oxaliplatin should be the standard method. A new standard for the palliative treatment of Her2/newly positive advanced gastric cancer and cancer at the gastro-esophageal junction is the administration of trastuzumab combined with chemotherapy. Patients with high-risk soft tissue sarcoma can be helped, in addition to surgical resection and subsequent radiotherapy, by neoadjuvant chemotherapy combined with regional deep hyperthermia. For patients with lung cancer additional individualized treatment is about to become routine. In addition to the EGFR mutation status, all non-smokers should in future be tested for aberration in the anaplastic lymphoma kinase (ALK) gene.

[Multimodality therapy of colorectal cancer]. / Multimodale Therapie des kolorektalen Karzinoms.

Adjuvant chemotherapy for resected stage III colon cancer is indicated for all patients, including elderly patients >70 years. In general, adjuvant oxaliplatin-fluoropyrimidine chemotherapy should be started within 6 weeks after tumor resection and should be given for a period of 6 months. However, patients aged >70 should receive fluoropyrimidine mono-chemotherapy. This mono-therapy, but not an oxaliplatin-based combination, can also be considered for patients with standard risk stage II tumors without microsatellite instability. In stage II patients with a high risk constellation adjuvant oxaliplatin-fluoropyrimidine combination therapy should be considered. Patients with stage II and III rectal cancer require neoadjuvant radiochemotherapy with fluoropyrimidine followed by adjuvant fluoropyrimidine treatment. There is no role for the use of VEGF- or EGFR-antibodies in the adjuvant therapy of colon cancer or in neoadjuvant therapy of rectal cancer. The prognosis of patients with primary resectable colorectal liver metastases may be improved by adjuvant or perioperative chemotherapy, while neoadjuvant systemic chemotherapy frequently facilitates potential curative resection of initially non-resectable liver metastases.

Identification of serum angiopoietin-2 as a biomarker for clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy.

BACKGROUND: The combination of chemotherapy with the vascular endothelial growth factor (VEGF) antibody bevacizumab is a standard of care in advanced colorectal cancer (CRC). However, biomarkers predicting outcome of bevacizumab-containing treatment are lacking. As angiopoietin-2 (Ang-2) is a key regulator of vascular remodelling in concert with VEGF, we investigated its role as a biomarker in metastatic CRC. METHODS: Serum Ang-2 levels were measured in 33 healthy volunteers and 90 patients with CRC. Of these, 34 had metastatic disease and received bevacizumab-containing therapy. To determine the tissue of origin of Ang-2, quantitative real-time PCR was performed on microdissected cryosections of human CRC and in a murine xenograft model of CRC using species-specific amplification. RESULTS: Ang-2 originated from the stromal compartment of CRC tissues. Serum Ang-2 levels were significantly elevated in patients with metastatic CRC compared with healthy controls. Amongst patients receiving bevacizumab-containing treatment, low pre-therapeutic serum Ang-2 levels were associated with a significant better response rate (82 vs 31%; P<0.01), a prolonged median progression-free survival (14.1 vs 8.5 months; P<0.01) and a reduction of 91% in the hazard of death (P<0.05). CONCLUSION: Serum Ang-2 is a candidate biomarker for outcome of patients with metastatic CRC treated with bevacizumab-containing therapy, and it should be further validated to customise combined chemotherapeutic and anti-angiogenic treatment.

Leukapheresis in chronic myelomonocytic leukemia with leukostasis syndrome: elevated serum lactate levels as an early sign of microcirculation failure.

We present the course of three patients suffering from chronic myelomonocytic leukemia (CMML), who presented with a markedly increase of their WBC (>200 G/l). All patients were started on chemotherapy consisting of ARA-C given as continuous infusion. Due to acute respiratory insufficiency, all patients were treated in the ICCU with ventilation support. Respiratory insufficiency was most likely due to pulmonary leukostasis since pulmonary infection or edema were excluded by X-ray in all patients. Therapeutic leukapheresis was therefore initiated and resulted in a dramatic improvement in one patient. Two patients died due to multiorganic failure despite effective leukocyte depletion (>40%) and maximum supportive care. At the onset of symptoms, two patients had markedly elevated serum lactate levels most likely due to microcirculatory failure. Both patients died because of deteriorating sequelae of pulmonary leukostasis, however, the patient with marginally elevated serum lactate levels survived. Leukapheresis is an established therapeutic approach in patients with hyperleukocytosis and leukostasis, which improves the prognosis of high-risk patients. In our opinion, patients presenting with asymptomatic hyperleukocytosis may benefit from early leukapheresis, particularly when increasing serum lactate levels indicate the early onset of microcirculatory failure.

Weekly irinotecan in a patient with metastatic colorectal cancer on hemodialysis due to chronic renal failure.

BACKGROUND: The cytotoxic treatment of patients suffering from advanced or metastatic cancer undergoing hemodialysis due to chronic renal failure still remains a problem, since for those patients pharmacokinetic and pharmacodynamic data on most cytotoxic agents are lacking. CASE REPORT: We report a 45-year-old male who suffered from chronic renal failure and was diagnosed with stage-3 colorectal cancer (CRC) in February 2000. After surgical removal of the tumor an adjuvant chemotherapy of dose-reduced i.v. bolus 5-fluorouracil and folinic acid was begun (Mayo protocol). Due to excessive gastrointestinal toxicity, therapy was discontinued after the first cycle. In April 2000 liver metastases were diagnosed. The patient was then put on a weekly schedule of dose-reduced CPT-11 (50 mg/m(2), 80 mg total). No hematological or non-hematological toxicity grade 3/4 was observed. Due to excellent tolerability and lack of severe side effects the dose was increased up to 80 mg/m(2) (140 mg total) weekly. A dose escalation to 100 mg/m(2) (180 mg total) resulted in severe diarrhea (grade 4). Within 2 months of treatment the patient achieved a lasting partial remission until April 2001 (12 months). A significant progression of hepatic metastases required an alternative treatment regimen beginning in July 2001 (HAI, hepatic artery infusion). CONCLUSION: This case report demonstrates the feasibility and efficacy of a weekly treatment with dose-reduced CPT-11 in a patient with metastatic CRC on hemodialysis due to chronic renal failure.

Efficient and selective AAV2-mediated gene transfer directed to human vascular endothelial cells.

Gene therapy vectors based on adeno-associated virus-2 (AAV2) offer considerable promise for human gene therapy. Applications for AAV vectors are limited to tissues efficiently transduced by the vector due to its natural tropism, which is predominantly skeletal muscle, neurons, and hepatocytes. Tropism modification to elevate efficiency and/or selectivity to individual cell types would enhance the scope of AAV for disease therapies. The vascular endothelium is implicitly important in cardiovascular diseases and cancer, but is relatively poorly transduced by AAV vectors. We therefore genetically incorporated the peptide SIGYPLP, which targets endothelial cells (EC), into position I-587 of AAV capsids. SIGYPLP-modified AAV (AAVsig) showed enhanced transduction of human EC compared with AAV with a wild-type capsid (AAVwt), a phenotype independent of heparan sulphate proteoglycan (HSPG) binding. In contrast, AAVsig did not enhance transduction of primary human vascular smooth muscle cells or human hepatocytes, principal targets for AAV vectors in local or systemic gene delivery applications, respectively. Furthermore, infection of EC in the presence of bafilomycin A(2) indicated that intracellular trafficking of AAV particles was altered by targeting AAV by means of SIGYPLP. AAV vectors with enhanced tropism for EC will be useful for diverse gene therapeutics targeted at the vasculature.

Influence of the IL-1Ra gene polymorphism on in vivo synthesis of IL-1Ra and IL-1beta after live yellow fever vaccination.

The inflammatory response in infectious and autoimmune diseases is regulated by the balance between pro- and anti-inflammatory cytokines. The IL-1 complex contains polymorphic genes coding for IL-1alpha, IL-1beta and IL-1Ra. The IL-1Ra (variable number of tanden repeat) VNTR polymorphism has been shown to influence the capacity to produce IL-1beta and IL-1Ra after in vitro stimulation. Allele 2 of this polymorphism is associated with a number of inflammatory diseases. To determine the impact of the IL-1Ra polymorphism on in vivo human cytokine synthesis, we used a yellow fever vaccination model for the induction of cytokine synthesis in healthy volunteers. Two different yellow fever vaccines were used. After administration of the RKI vaccine (34 volunteers), plasma TNF-alpha concentration increased from 13.4 +/- 0.9 pg/ml to 23.3 +/- 1.1 pg/ml (P < 0.001), and plasma IL-1Ra concentration increased from 308 +/- 25 pg/ml to 1019 +/- 111 pg/ml (P < 0.001), on day 2. Using Stamaril vaccine, no increase in the plasma concentrations of either TNF-alpha or IL-1Ra could be detected (n = 17). Only the RKI vaccine induced TNF-alpha synthesis after in vitro stimulation of MNC. Carriers of allele 2 of the IL-1Ra polymorphism had increased baseline concentrations of IL-1Ra (350 +/- 32 pg/ml) compared with non-carriers (222 +/- 18 pg/ml, P < 0.001), and decreased concentrations of IL-1beta (0.9 +/- 0.2 pg/ml for carriers versus 2.8 +/- 0.7 pg/ml for non-carriers, P = 0.017). After yellow fever vaccination (RKI vaccine), no significant differences in the increase of IL-1Ra plasma levels were detected between carriers and non-carriers of allele 2 of the IL-1Ra gene polymorphism. This is the first study to examine the influence of this genetic polymorphism on in vivo-induced human IL-1beta and IL-1Ra synthesis. Baseline concentrations of IL-1Ra and IL-1beta were significantly influenced by the IL-1Ra polymorphism. No influence of the IL-1Ra polymorphism on the in vivo-induced production of IL-1Ra and IL-1beta could be detected.

Dual role of the fringe connection gene in both heparan sulphate and fringe-dependent signalling events.

The precise regulation of growth factor signalling is crucial to the molecular control of development in Drosophila. Post-translational modification of signalling molecules is one of the mechanisms that modulate developmental signalling specificity. We describe a new gene, fringe connection (frc), that encodes a nucleotide-sugar transporter that transfers UDP-glucuronic acid, UDP-N-acetylglucosamine and possibly UDP-xylose from the cytoplasm into the lumen of the endoplasmic reticulum/Golgi. Embryos with the frc mutation display defects in Wingless, Hedgehog and fibroblast growth factor signalling. Clonal analysis shows that fringe-dependent Notch signalling is disrupted in frc mutant tissue.

Standard heparin, low molecular weight heparin, low molecular weight heparinoid, and recombinant hirudin differ in their ability to inhibit transduction by recombinant adeno-associated virus type 2 vectors.

Recombinant adeno-associated virus type 2 (rAAV) is a promising vector for in vivo gene therapy. Transduction by rAAV requires binding to heparan sulfate proteoglycan on the cell surface, and heparin can block this binding. Because heparin is administered to most patients undergoing cardiovascular gene transfer in order to prevent thrombotic events, it is important to identify anticoagulants which do not interfere with rAAV transduction. Therefore, we examined the influence of different anticoagulants on rAAV transduction in vitro. rAAV transduction was inhibited by 40.5 +/- 7.9% at heparin concentrations of 0.1 U/ml, and by 81.7 +/- 3.6% at 1.0 U/ml. The low molecular weight (LMW) heparin tinzaparin inhibited rAAV transduction by 20.2 +/- 3.8% at 0.1 U/ml and 37.1 +/- 1.8% at 1.0 U/ml. The inhibitory effect was significantly weaker compared with heparin at 1.0 U/ml, (P < 0.01). The LMW heparinoid danaparoid inhibited rAAV transduction by 8.8 +/- 3.5% at 0.1 U/ml (P < 0.01 compared with heparin). In contrast, recombinant hirudin did not interfere at all with rAAV transduction. In summary, the results demonstrate that inhibition of rAAV transduction by heparin occurs rapidly and at therapeutically used concentrations. LMW heparinoids and above all recombinant hirudin might be alternatives for heparin when vascular gene transfer with rAAV requires transient anticoagulation.