Semiconductor quantum dots for multiplexed bio-detection on solid-state microarrays.

International audienc

Single- and two-photon imaging of human micrometastases and disseminated tumour cells with conjugates of nanobodies and quantum dots.

Early detection of malignant tumours and, especially, micrometastases and disseminated tumour cells is still a challenge. In order to implement highly sensitive diagnostic tools we demonstrate the use of nanoprobes engineered from nanobodies (single-domain antibodies, sdAbs) and fluorescent quantum dots (QDs) for single- and two-photon detection and imaging of human micrometastases and disseminated tumour cells in ex vivo biological samples of breast and pancreatic metastatic tumour mouse models expressing human epidermal growth factor receptor 2 (HER2) or carcinoembryonic antigen (CEA). By staining thin (5-10 µm) paraffin and thick (50 µm) agarose tissue sections, we detected HER2- and CEA-positive human tumour cells infiltrating the surrounding tissues or metastasizing to different organs, including the brain, testis, lung, liver, and lymph nodes. Compared to conventional fluorescently labelled antibodies the sdAb-HER2-QD and sdAb-CEA-QD nanoprobes are superior in detecting micrometastases in tissue sections by lower photobleaching and higher brightness of fluorescence signals ensuring much better discrimination of positive signals versus background. Very high two-photon absorption cross-sections of QDs and small size of the nanoprobes ensure efficient imaging of thick tissue sections unattainable with conventional fluorescent probes. The nanobody-QD probes will help to improve early cancer diagnosis and prognosis of progression by assessing metastasis.Open-Access-Publikationsfonds 2018peerReviewe

Phage Display and Selections on Purified Antigens

International audienceThe isolation of antibody fragments targeting proteins implicated in cancers and other diseases remains a crucial issue on targeted therapy or diagnostic tool development. In many case, the protein of interest, or a relevant portion of this protein such as its extracellular domain, is available as purified protein. In such cases, phage display on purified antigen is an easy and fast way to select antibody fragment able to efficiently bind this antigen. However the output of phage selection can vary significantly depending on the way to immobilize the purified antigen during selection. The following protocols describe the selection of phage antibody on purified antigen adsorbed on plastic, i.e., panning, or a selection in solution, using a biotinylated antigen as well as the corresponding screening produces, and give hints on the advantage and drawbacks of each approach

Therapeutic application of monoclonal antibodies in cancer: advances and challenges

IntroductionMonoclonal antibody (mAb)-based products are highly specific for a particular antigen. This characteristic feature of the molecules makes them an ideal tool for many applications including cancer diagnosis and therapy.Sources of dataWe performed comprehensive searches of PubMed, Medline and the Food and Drug Administration website using keywords such as 'therapeutic antibodies' and 'anti-cancer antibodies'.Areas of agreementTreatment of cancer patients with antibodies when used alone or in combination with chemotherapy and radiotherapy, or conjugated to drugs or radioisotopes, prolongs overall survival in cancer patients. Currently, there are 14 mAb-based drugs that have been approved for the treatment of cancer patients.Areas of controversyThe response of cancer patients to antibody therapy can be of short duration. Therapeutic antibodies are expensive and may have side effects. There are no reliable predictive biomarkers for sensitivity or resistance to certain therapeutic antibodies.Future focusThere should be additional studies to discover novel therapeutic targets, to develop more effective antibody-based drugs with fewer side effects, to identify more reliable predictive biomarker(s) for response to therapy with antibody-based drugs and to develop alternative strategies (e.g. transgenic plants, transgenic farm animals) for production of large quantities and more affordable batches of therapeutic antibodies.Areas timely for developing researchA better understanding of cancer biology, the hallmarks of human cancers and the immune system would lead to identification of additional cell surface biomarkers. These in turn would facilitate the development of novel and biosimilar antibody-based drugs and their routine use as 'magic bullets' for the targeted therapy of human cancers