HER3 as biomarker and therapeutic target in pancreatic cancer: new insights in pertuzumab therapy in preclinical models.

International audienceThe anti-HER2 antibody pertuzumab inhibits HER2 dimerization and affects HER2/HER3 dimer formation and signaling. As HER3 and its ligand neuregulin are implicated in pancreatic tumorigenesis, we investigated whether HER3 expression could be a predictive biomarker of pertuzumab efficacy in HER2low-expressing pancreatic cancer. We correlated in vitro and in vivo HER3 expression and neuregulin dependency with the inhibitory effect of pertuzumab on cell viability and tumor progression. HER3 knockdown in BxPC-3 cells led to resistance to pertuzumab therapy. Pertuzumab treatment of HER3-expressing pancreatic cancer cells increased HER3 at the cell membrane, whereas the anti-HER3 monoclonal antibody 9F7-F11 down-regulated it. Both antibodies blocked HER3 and AKT phosphorylation and inhibited HER2/HER3 heterodimerization but affected differently HER2 and HER3 homodimers. The pertuzumab/9F7-F11 combination enhanced tumor inhibition and the median survival time in mice xenografted with HER3-expressing pancreatic cancer cells. Finally, HER2 and HER3 were co-expressed in 11% and HER3 alone in 27% of the 45 pancreatic ductal adenocarcinomas analyzed by immunohistochemistry. HER3 is essential for pertuzumab efficacy in HER2low-expressing pancreatic cancer and HER3 expression might be a predictive biomarker of pertuzumab efficacy in such cancers. Further studies in clinical samples are required to confirm these findings and the interest of combining anti-HER2 and anti-HER3 therapeutic antibodies

Targeting HER3 receptor with therapeutic antibodies

De part, leur implication dans la prolifération cellulaire, l'invasion et leur surexpression dans de nombreux cancers, les récepteurs à tyrosine kinase de la famille HER constituent des cibles de choix en oncologie. Parmi ces récepteurs, le récepteur HER3 semble pertinent car il est impliqué dans la tumorigenèse de nombreux cancers (sein, ovaire, pancréas, mélanome…) et il est associé à un mauvais pronostic. De plus, la surexpression du récepteur HER3 est souvent associée à l'apparition de résistance aux thérapies ciblées. Nous avons sélectionné plusieurs anticorps anti-HER3 humains et murins respectivement par « phage display » et fusion cellulaire. Ces derniers reconnaissent spécifiqument le récepteur HER3. Parmi les nombreux anticorps découvert, nous avons sélectionné un anticorps anti-HER3 humain H4B-121 et 2 anticorps anti-HER3 murins 9F7-F11 et 16D3-C1. Ces derniers ont la capacité à faire régresser des tumeurs épidermoide, pancréatique et triple négative chez la souris, en présence ou en abscence de neuréguline et indépendamment du status HER2 et P53/PTEN. Cette inhibition est possible grâce à un blocage du cycle cellulaire en phase G1, une inhibition de la prolifération ainsi qu'une induction de l'apoptose. Ces trois anticorps sont capables de bloquer l'hétérodimérisation des récepteurs HER2/HER3 ainsi que la phosphorylation du récepteur HER3. Ils sont aussi capables d'inhiber la phosphorylation de la protéine AKT ainsi que de ses cibles (MDM2, FOXO et XIAP). De plus, nous avons montré que nos anticorps sont capables de lyser les cellules tumorales par ADCC (Antibody-dependent cell-mediated cytotoxicity). Cette étude démontre que ces anticorps anti-HER3 représentent une nouvelle thérapie pour les cancers du pancréas et du sein triple négatif.Due to their implication in the cellular proliferation, the invasion and their surexpression in numerous cancers, the tyrosine kinase receptors of HER family constitute one of the best targets in oncology. Within this family, the human epidermal growth factor receptor 3 (HER3) plays a role in tumorigenesis of different cancers (Breast, melanoma, pancreas and ovary). This receptor is implicated in drug resistance and he is over expressed in cancers that are not eligible for the currently approved targeted therapies. To this end, we generated specific antibodies (Abs) against domain 1 (D1) and domain 3 (D3) of HER3 that recognize epitopes that do not overlap with the neuregulin-binding site. The fully human H4B-121 Ab and the mouse monoclonal Abs 16D3-C1 and 9F7-F11 inhibited tumor growth in nude mice xenografted with epidermoid, pancreatic, or triple-negative breast cancer cells independently of NRG addiction, HER2 status and p53/PTEN mutations. The combination of one anti-HER3 Ab and trastuzumab improved tumor growth inhibition in mice xenografted with HER2(low) cancer cell lines, for which trastuzumab alone shows no or moderate efficiency. Ab-induced disruption of tumor growth was associated with G1 cell cycle arrest, proliferation inhibition, and apoptosis of cancer cells. Anti-HER3 Abs blocked HER2/HER3 heterodimerization and HER3 phosphorylation at the cell membrane, leading to inhibition of phosphorylation of the downstream AKT targets murine double minute 2, X-linked inhibitor of apoptosis, and forkhead box O1. Anti-HER3 Abs can also induice antibody dependant cell-mediated cytotoxicity. This study demonstrates that anti-HER3 D1 and D3 Abs could represent a new option for immunotherapy of pancreatic and triple-negative breast cancers

Molecular detection of human Plasmodium species using a multiplex real time PCR

International audienceMolecular detection methods have revealed higher sensitivity and specificity than conventional microscopy or rapid diagnostic tests for malaria diagnosis. In this study, we implemented, evaluated and validated according to the ISO 15,189 requirements, a multiplex real-time PCR assay to detect and identify the five human malaria parasites. DNA samples were extracted from whole blood or dried blood spots drawn from patients. Based on the External Quality Assessment (whole blood), this method shows 100% sensitivity and specificity. This PCR detected P. vivax up to 0.25 p/µl, P. falciparum and P. knowlesi up to 0.5 p/µl, P. ovale up to 1 p/µl and P. malariae up to 5 p/µl of blood. From blood spots (extraction from four punches), it detected P. vivax at 5 p/µl, P. falciparum , P. ovale and P. knowlesi at 20 p/µl and P. malariae at 125 p/µl. In conclusion, this quantitative PCR shows excellent performance, is easy to use and DNA saver. It is especially useful to actively screen large population groups and identify the five human malaria parasites in a context of low malaria transmission

Paludisme et orpaillage illégal en Guyane : un enjeu majeur de santé publique

National audienceIntroduction – Le nombre d’accès palustres diminue globalement en Guyane, alors que les orpailleurs travaillantsur les sites illégaux semblent particulièrement touchés par cette pathologie. Les objectifs de cette étudeétaient de déterminer la prévalence du paludisme dans cette population, les comportements associés ainsi quele niveau de résistance des parasites vis-à-vis des dérivés de l’artémisinine.Matériel et méthodes – Les inclusions ont eu lieu sur les sites de repli fréquentés par les orpailleurs le long dufleuve Maroni. Ont été effectués : un test de diagnostic rapide du paludisme, un questionnaire, un prélèvementsanguin pour PCR et un génotypage du gène pfK13 pour les PCR positives à Plasmodium falciparum.Résultats – De janvier à juin 2015, 421 orpailleurs ont été inclus, majoritairement des hommes (70,6%) brésiliens(93,8%). La prévalence du portage de plasmodies déterminée par PCR était en moyenne de 22,3%(IC95%: [18,3-26,3]), à 84% asymptomatiques. Les espèces identifiées étaient principalement P. falciparum(47,9%) puis P. vivax (37,2%), plus 10,6% de co-infections. Lors du dernier accès palustre, 52,4% des orpailleursavaient eu recours à l’automédication, majoritairement avec des dérivés de l’artémisinine (93,8%) avecune mauvaise observance (37,8%). L’analyse du gène pfK13 n’a pas mis en évidence de mutations associéesà la résistance à P. falciparumDiscussion – La prévalence élevée de porteurs asymptomatiques de plasmodies constitue un réservoir importantde transmission dans la région. L’utilisation massive de dérivés de l’artémisinine associée à une mauvaise observancedes traitements sont des facteurs de risque d’émergence de résistance imposant des mesures rapide

Risk factors linked to mobility outside the area around one’s home for <i>P</i>. <i>vivax</i> carriage among the whole study population, among children (under 18 years old) and among adults (18 years old and above.

Risk factors linked to mobility outside the area around one’s home for P. vivax carriage among the whole study population, among children (under 18 years old) and among adults (18 years old and above.</p

<i>Plasmodium</i> spp. carriage prevalence in the study population in 2017 and 2018 according to neighbourhood.

Plasmodium spp. carriage prevalence in the study population in 2017 and 2018 according to neighbourhood.</p

Study population distribution in the 12 different neighbourhoods of SGO which were included.

Study population distribution in the 12 different neighbourhoods of SGO which were included.</p

Study flow chart.

Despite the large reduction in malaria incidence in the last decade, the last kilometre to elimination is often the hardest, especially in international border areas. This study investigated the impact of mobility on Plasmodium spp. carriage in people living in a cross-border area in Amazonia with a low malaria transmission rate. We implemented a longitudinal ancillary study in the French Guiana town of St. Georges de l’Oyapock, which is located on the border with Brazil. It was based on data from two transversal surveys performed in October 2017 and October 2018. Data were collected on peri-domestic mobility for food-producing activities, and longer-distance mobility in high-risk areas. Participants were screened for Plasmodium spp. carriage using PCR tests, and treated if positive. Vector density around a participant’s home was estimated using a previously published model based on remote sensing and meteorological data. The association between Plasmodium spp. carriage and mobility was analysed using a generalized additive mixed model. A total of 1,192 inhabitants, aged between 0 and 92 years old, were included. Median age was 18 years in 2017 (IQR [8;35]). Plasmodium spp. prevalence in the study population was 7% in 2017 (n = 89) and 3% in 2018 (n = 35). Plasmodium spp. carriage was independently associated with i) travel to the adjoining Oiapoque Indigenous Territories in Brazil (OR = 1.76, p = 0.023), ii) the estimated vector density around a participant’s home (High versus Low risk OR = 4.11, p</div

Declines in prevalence alter the optimal level of sexual investment for the malaria parasite Plasmodium falciparum

International audienceSuccessful infectious disease interventions can result in large reductions in parasite prevalence. Such demographic change has fitness implications for individual parasites and may shift the parasite’s optimal life history strategy. Here, we explore whether declining infection rates can alter Plasmodium falciparum ’s investment in sexual versus asexual growth. Using a multiscale mathematical model, we demonstrate how the proportion of polyclonal infections, which decreases as parasite prevalence declines, affects the optimal sexual development strategy: Within-host competition in multiclone infections favors a greater investment in asexual growth whereas single-clone infections benefit from higher conversion to sexual forms. At the same time, drug treatment also imposes selection pressure on sexual development by shortening infection length and reducing within-host competition. We assess these models using 148 P. falciparum parasite genomes sampled in French Guiana over an 18-y period of intensive intervention (1998 to 2015). During this time frame, multiple public health measures, including the introduction of new drugs and expanded rapid diagnostic testing, were implemented, reducing P. falciparum malaria cases by an order of magnitude. Consistent with this prevalence decline, we see an increase in the relatedness among parasites, but no single clonal background grew to dominate the population. Analyzing individual allele frequency trajectories, we identify genes that likely experienced selective sweeps. Supporting our model predictions, genes showing the strongest signatures of selection include transcription factors involved in the development of P. falciparum ’s sexual gametocyte form. These results highlight how public health interventions impose wide-ranging selection pressures that affect basic parasite life history traits