[Contribution of connected prescriptions (NetSIG) for the management of molecular pathology exams]

INTRODUCTION

This study describes our experience implementing a connected prescription software (NetSIG, Terascop) for molecular pathology exams.

MATERIAL AND METHODS

NetSIG was set up for liquid biopsies and tissue testing. After registration and activation of regional pathology laboratories, NetSIG was implemented for external then internal prescriptions.

RESULTS

NetSIG allows users to follow up on all prescriptions on the website, to interact through messages and to consult reports after validation. External set up was quick (3-4 months) and comprehensive (>70%). Prescriptions were made by physicians or more often by secretaries or referring pathologists. Internal prescriptions were made by pathologists then registered in NetSIG by our secretaries. This deployment strategy has resulted in very good completeness of prescriptions (>90%).

DISCUSSION AND CONCLUSION

Connected prescriptions made this complex circuit more fluid and facilitated the redistribution of different administrative and technical tasks. The number of phone calls decreased sharply. Half of the prescriptions were made by pathologists and half by oncologists (physicians or secretaries). The mean dearchiving duration for blocks was one day. Mean forwarding of blocks was 2.5 days. Mean turnaround time was 8 days for targeted techniques and 13 days for Next Generation Sequencing. Physicians appreciated the interactivity of the software and the fact that they could consult it on a smartphone.

Idylla EGFR assay on extracted DNA: advantages, limits and place in molecular screening according to the latest guidelines for non-small-cell lung cancer (NSCLC) patients

AIMS

Idylla epidermal growth factor receptor (EGFR) is a fast and fully automated mutation assay that is easy to implement. However, under the Biocartis-recommended technical conditions, tissue sections are directly introduced into the cartridge, at the risk of exhausting the tumour sample. In this study, we evaluate the performance of Idylla EGFR on extracted DNA and discuss its place within the global non-small-cell lung cancer (NSCLC) screening strategy.

METHODS

577 comparative tests between Idylla EGFR on extracted DNA and next-generation sequencing (NGS) were performed across two centres.

RESULTS

Preanalytical thresholds were established (20% tumour cell content, 50 ng DNA input) and challenged prospectively in routine practice. 16.8% of samples referred for screening were considered non eligible for Idylla EGFR testing. Due to discordant by design cases, Idylla EGFR sensitivity was 86.9% for currently actionable EGFR mutations. Idylla EGFR specificity was 100% in first-line screening. NGS was always feasible on the same DNA.

CONCLUSION

Idylla EGFR on extracted DNA is feasible and enables tumour material to be saved compared with tissue section use. It is not necessary to replace the analytical thresholds of the Biocartis algorithm. Due to both the limits of the mutational repertoire and the high increase of targetable genes in NSCLC, the use of Idylla EGFR should be restricted to clinical emergency situations accompanied by NGS.

The impact of the prevention programme of hepatitis C over more than a decade: the French experience

To assess the impact of the French national hepatitis C prevention programme initiated in 1999, we analysed trends in hepatitis C virus (HCV) prevalence, testing and characteristics of HCV-infected patient at first referral from 1994 to 2006. We used four data sources: Two national population-based sero-prevalence surveys carried out in 1994 and 2004; two surveillance networks, one based on public and private laboratories throughout France and the other on hepatology reference centres, which aim to monitor, respectively, trends of anti-HCV screening and of epidemiological-clinical characteristics of HCV patients at first referral. Between 1994 and 2004, the anti-HCV prevalence for adults aged 20-59 years decreased from 1.05 (95% confidence interval 0.75-1.34) to 0.71 (0.52-0.97). During the same period, those anti-HCV positive with detectable HCV RNA decreased from 81 to 57%, whereas, the proportion of anti-HCV positive persons aware of their status evolved from 24 to 56%. Anti-HCV screening activity increased by 45% from 2000 to 2005, but decreased in 2006 (-10%), while HCV positivity among those tested decreased from 4.3 to 2.9%. The proportion of cirrhosis at first referral remains around 10% between 2001 and 2006, with many patients with excessive alcohol consumption (34.7% among males) or viral co-infections (HIV seropositivity for 5.2% patients). Our analysis indicates that the national programme had a positive impact at the population level through improved prevention, screening and management. There is still a need to identify timely those at risk for earlier interventions, to assess co-morbidities better and for a multidisciplinary approach to HCV management.

Dendritic cells route human immunodeficiency virus to lymph nodes after vaginal or intravenous administration to mice

We have developed a murine model to study the involvement of dendritic cells (DC) in human immunodeficiency virus (HIV) routing from an inoculation site to the lymph nodes (LN). Murine bone marrow-derived DC migrate to the draining LN within 24 h after subcutaneous injection. After incubation of these cells with heat-inactivated (Hi) HIV type 1 (HIV-1), HIV RNA sequences were detected in the draining LN only. Upon injection of DC pulsed with infectious HIV, the virus recovered in the draining LN was still able to productively infect human T cells. After a vaginal challenge with Hi HIV-1, the virus could be detected in the iliac and sacral draining LN at 24 h after injection. After an intravenous challenge, the virus could be detected in peripheral LN as soon as 30 min after injection. The specific depletion of a myeloid-related LN DC population, previously shown to take up blood macromolecules and to translocate them into the LN, prevented HIV transport to LN. Together, our data demonstrate the critical role of DC for HIV routing to LN after either a vaginal or an intravenous challenge, which does not require their infection. Therefore, despite the fact that the mouse is not infectable by HIV, this small animal model might be useful to test preventive strategies against HIV.

[Dendritic cells and tumor cell therapy]

Antigen presentation to T lymphocytes appears to be one of the deficient step in the induction of anti-tumoral immune responses. To overcome this deficit, it should be possible to use the professional antigen presenting dendritic cells. The principle of this strategy would be to purify dendritic cells, to prime them ex vivo with tumoral antigen, and to re-inject them to patient. The purification of dendritic cells can be achieved from the spleen, bone marrow, and peripheral or cord blood. Their sensitization to tumoral antigen could be obtained using various antigeneic preparation such as crude tumoral extract, or purified antigen, that will lead to an MHC class II restricted antigenic presentation to CD4+ T cells. Gene transfer can be used in the case of a cloned antigen and would lead to the restricted MHC class I priming of CD8+ T cells. The mode of administration, the nature of the dendritic cells used, the number of sensitized cells to inject, might depend on the nature and the location of the tumour. In vitro, it has been shown that dendritic cells sensitized with tumoral antigen are capable of triggering proliferative immune responses as well as cytotoxic T cells. In vivo, injection of dendritic cells primed with tumour cell lysate leads to protection of mice against a tumour challenge. Finally, gene transfer to dendritic cells is shown hereby to be possible, although the efficacy of transduction is still very low, and must be improved. Altogether, it should soon be feasible to use ex vivo primed dendritic cells for triggering otherwise inefficient immune responses in pathologies such as cancer or HIV infection.

Conditional ablation of dendritic cells in transgenic mice

Dendritic cells (DC) are professional Ag-presenting cells that play a major role in T cell-mediated immune responses and in thymocyte differentiation. To better analyze their physiological importance, we sought to generate transgenic mice presenting a conditional DC deficiency. We used a strategy based on the cell-specific expression of a suicide gene. The DC-targeted expression is obtained using HIV regulatory sequences; indirect evidence has suggested that these sequences control a preferential expression in DC. The suicide gene is the herpes simplex virus type 1 thymidine kinase (HSV1-TK) which allows conditional ablation of dividing HSV1-TK-expressing cells by converting nucleoside analogs such as ganciclovir (GCV) into toxic molecules. We generated transgenic mice expressing an HSV1-TK gene transcribed from HIV regulatory sequences. A low but significant HSV1-TK expression was observed in mature DC and DC precursors grown from granulocyte-macrophage colony-stimulating factor-supplemented bone marrow cultures. These HSV1-TK-expressing DC precursors are specifically killed by GCV. We next treated transgenic mice with GCV, and obtained a specific ablation of DC in spleen and thymus. Ninety percent of spleen DC could be depleted within a week, indicating a turnover rate of approximately 15% per day. Interestingly, this DC depletion always correlated with a major thymic atrophy and disappearance of CD4+CD8+ thymocytes. This animal model should help to assess the physiological role of DC in the immune response and in thymocyte differentiation. It should also help to appreciate the consequences of DC dysfunction in pathological situations, such as HIV-infection or allograft rejection.

Conditional ablation of dendritic cells in transgenic mice

Dendritic cells (DC) are professional Ag-presenting cells that play a major role in T cell-mediated immune responses and in thymocyte differentiation. To better analyze their physiological importance, we sought to generate transgenic mice presenting a conditional DC deficiency. We used a strategy based on the cell-specific expression of a suicide gene. The DC-targeted expression is obtained using HIV regulatory sequences; indirect evidence has suggested that these sequences control a preferential expression in DC. The suicide gene is the herpes simplex virus type 1 thymidine kinase (HSV1-TK) which allows conditional ablation of dividing HSV1-TK-expressing cells by converting nucleoside analogs such as ganciclovir (GCV) into toxic molecules. We generated transgenic mice expressing an HSV1-TK gene transcribed from HIV regulatory sequences. A low but significant HSV1-TK expression was observed in mature DC and DC precursors grown from granulocyte-macrophage colony-stimulating factor-supplemented bone marrow cultures. These HSV1-TK-expressing DC precursors are specifically killed by GCV. We next treated transgenic mice with GCV, and obtained a specific ablation of DC in spleen and thymus. Ninety percent of spleen DC could be depleted within a week, indicating a turnover rate of approximately 15% per day. Interestingly, this DC depletion always correlated with a major thymic atrophy and disappearance of CD4+CD8+ thymocytes. This animal model should help to assess the physiological role of DC in the immune response and in thymocyte differentiation. It should also help to appreciate the consequences of DC dysfunction in pathological situations, such as HIV-infection or allograft rejection.