PhD Scientific Days 2021

CL_V_P: Clinical Medicine V. Posters

Novel Liquid Biopsy Markers of Central Nervous System Involvement in Pediatric Acute Lymphoblastic Leukemia

Text of the abstract

Introduction: Refractory central nervous system (CNS) involvement is among the major causes of therapy failure in childhood acute leukemia. Applying contemporary diagnostic methods, CNS disease is often underdiagnosed.

Aims: To explore more sensitive CNS status indicators, we examined microRNA (miR) expression in body fluids of patients with pediatric leukemia. The main set of proteins associated with CNS trafficking and regulated by our candidate miRs were also studied in correlation with miR expressions.

Methods: In an acute lymphoblastic leukemia (ALL) discovery cohort, 47 miRs were screened using Custom TaqMan Advanced Low-Density Array gene expression cards. As a validation step, a selected promising miR family was further scrutinized with TaqMan Advanced miRNA Assays on serial cerebrospinal fluid (CSF), bone marrow (BM) and peripheral blood samples (n=132). Next, enzyme-linked immunosorbent assays were used to measure vascular endothelial growth factor A (VEGF-A) and integrin alpha 6 (ITGA6) levels in CSF and BM samples.

Results: Regarding the discovery study, principal component analysis identified the role of miR-181-family (miR-181a, -181b, -181c) in clustering CNS-positive (CNS+) and CNS-negative (CNS‒) CSF samples. We were able to validate miR-181a expression differences: it was about 52 times higher in CSF samples of patients with CNS+ ALL compared to CNS‒ cases (n=8 vs. n=10, ΔFC=52.30, p=1.5E-4). The sensitivity of CSF miR-181a measurement highly exceeded those of conventional cytospin in the initial diagnosis of CNS+ ALL (90.0% vs. 54.5%). Decrease in miR-181a level from the diagnosis of ALL to the 33rd day of therapy was also detectable in BM samples among CNS+ patients (ΔFC=-187.96, p=0.006). Analysis of CSF and BM samples of the validation cohort revealed a slight correlation between miR-181a and VEGF-A levels (n=46, Pearson’s r=0.36, p=0.015). In addition, CSF VEGF-A concentration distinguished patients with CNS+ and CNS‒ ALL (p=0.023), which is in parallel with previous preclinical data from the literature.

Conclusion: After validating in international cohorts, quantification of miR-181a and/or VEGF-A might provide novel tools to adjust CNS-directed therapy in pediatric ALL.

Funding: New National Excellence Program (ÚNKP-20-3-II-SE-20) and Co-operative Doctoral Program (KDP-2020/1008491) of the Ministry of Innovation and Technology

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine