Liquid Micro-biopsy: a Novel Approach to Study Tumor Microenvironment From the Peripheral Blood

Overview

This is a prospective multicentre, tissue-based, non-profit study that includes two enrolling centres: Operating Unit (OU) No. 1 of Haematology and OU No. 2 of Medical Oncology, both at the IRCCS Azienda Ospedaliera-Universitaria di Bologna (AOUBO). Given the rarity of the pathology investigated and the lack of evidence from the literature, the study should be considered exploratory, aimed at providing provisional evidence and generating hypotheses that could be tested in future studies. The study involves the collection of peripheral blood samples from healthy volunteers (HD) matched for sex/age (n=30; Group 1) and patients with acute myeloid leukaemia at diagnosis (n=30; Group 2) at UO1 and patients with visceral sarcoma with measurable disease (n=30; Group 3) at UO2. Specifically, peripheral blood (equal to 60 mL) from healthy volunteers will be collected after obtaining the signed informed consent of the volunteers of the Associazione Onlus AIL Bologna ODV. From all participants in Groups 2 and 3, 60 mL of peripheral blood and 20 mL of bone marrow blood will be collected at routine clinical examinations. Bone biopsies (10 sections) will also be collected from Group 2 patients. All samples will be collected at the time of diagnosis (T0). All samples will be centralised at the Haematology Unit, IRCCS AOUBO and submitted for laboratory analysis. For patients with acute myeloid leukaemia, responses to treatment will be assessed on the basis of standard criteria according to the recommendations of the European LeukemiaNet of 2022 (Döhner H et al, Blood 2022). Clinical response for sarcoma patients according to the international RECIST imaging criteria assessed by routine computed tomography or magnetic resonance imaging scans.

Survival of AML is globally poor, with an overall survival at 5 years largely inferior to 50%. The diagnosis of several diseases, such as AML relies on invasive procedures. An increasing amount of evidence supports the straightforward relations between bone marrow (BM) biopsies and blood in hematological malignancies, including AML. Novel approaches to the characterization of TME have been developed. In this regard, scRNA-seq analysis emerged as a potent tool, capable of profoundly characterizing genomic profiles at the single-cell level. However, ST have the potential to improve our understanding of TME composition and cellular interactions, representing a powerful tool capable of identifying cell types and gene expression profiles on a structural and spatial level. Since the question of a comprehensive characterization of tumor heterogeneity and cell-cell interactions is still unsolved, new ways to detect its modulation using blood are highly warranted for tumor diagnosing and monitoring. Indeed, conventional and invasive methods are insufficient to decipher the heterogeneous nature of tumors. Based on these premises, the driving hypothesis of the study is that performing an in-parallel analysis on both circulating cells and EVs might provide a broader characterization of the genomic landscape of tumors than using cells themselves. The integration of LB within the clinical management of cancer patients may represent an essential step towards a deeper understanding of cancer biology. It might have important implications for better disease monitoring and improved drug development.