Design, Development, and Validation of Novel "Next Generation Flow" Approaches for Rapid, Specific, Sensitive, and Reproducible Detection of Tumor Cells in Cutaneous T-cell Lymphoma.

Primary cutaneous lymphomas are a group of tumors derived from lymphocytes (mostly T lymphocytes) that primarily affect the skin (such as mycosis fungoides, MF), although they can spread beyond the skin in more advanced stages - for example, to the blood - or may already be disseminated initially, as is the case with Sézary syndrome (SS), a tumor with very aggressive behavior from the beginning, which by definition already has blood dissemination at diagnosis. They are very rare tumors and difficult to diagnose because often the skin lesions are indistinguishable from benign processes (the latter much more common than cutaneous lymphomas). For this reason, it is not uncommon for the diagnosis to be delayed, with the consequent negative impact on the patient's prognosis if it is a tumor. Currently, the diagnosis of blood dissemination (the amount of which is also essential because it impacts the prognosis, the worse the higher tumor burden in the blood) is performed by flow cytometry, which has replaced conventional morphology. However, the flow cytometry techniques currently used in most clinical laboratories are not standardized among different centers, and therefore the comparability of the results (even over time, in the same center) and their use in the clinical settings is difficult.

In this project, the investigators HYPOTHESIZE that the application of novel "next-generation flow" strategies proposed by the international collaborative group EuroFlow (to which the applicant of this proposal belongs) would improve the detection of circulating tumor cells in patients with cutaneous T-cell lymphoma, which would allow improving the clinical management of the patients. Therefore, in this project, the aim as a GENERAL OBJECTIVE to apply standardized strategies of next-generation flow cytometry developed by the EuroFlow Consortium for the rapid, specific, sensitive, and reproducible detection and quantification of tumor cells in patients with MF/SS, through: i) the application of standardized sample staining procedures with antibody panels designed after previous rounds of testing, which would allow distinguishing tumor T lymphocytes from normal T cells (specificity); ii) adapting the technique to analyze a large number of cells, in order to achieve a high sensitivity of detection, also crucial for a more precise monitoring of residual disease in blood after treatment with the new therapies available in cutaneous T-cell lymphomas; and iii) development of automatic analysis strategies of cytometry data, so that the results do not depend on the personal experience of the cytometrist.

IMPACT. The availability of a new standardized flow cytometry strategy for sensitive and specific detection (and quantification) of circulating tumor cells in blood (and skin) of patients with cutaneous T-cell lymphoma will provide an essential tool to support dermo-hematological diagnosis, with the possibility of translating to routine diagnosis in the very short term after the completion of the project, for its application in hospitals that have a Cytometry/Immunopathology Laboratory, with the aim of: i) Making an early and accurate (differential) diagnosis between lymphoma - benign lesion in patients with skin lesions; ii) Detecting tumor cells in blood with greater sensitivity than conventional methods, to more precisely establish blood dissemination of a primary cutaneous T-cell lymphoma, and to assess the response to current treatments in a more reliable and sensitive way