INITIAL EXPERIENCE IN ESTIMATING TUMOR MUTATION BURDEN IN PEDIATRIC HEPATOCELLULAR CARCINOMA
The level of tumor mutation burden (TMB) is a predictive factor of immune checkpoints that determines the potential effectiveness of immune checkpoint inhibitors and indications for their prescription regardless of the type of tumor in adults and children. However, the prevalence of tumors with high TMB in the pediatric population has not been well studied. Objective of the research: to assess the detection frequency of high TMB (>10 mutations per megabase) in pediatric hepatocellular carcinoma (HCC). Materials and methods of research: Next Generation Sequencing, Ion AmpliSeq™ Comprehensive Cancer Panel (409 genes) of tumor DNA samples from 4 children with HCC was performed. The calculation of the mutational load was carried out according to the work of Z.R. Chalmers et al. Results: out of 4 analyzed samples, TMB levels have lower cut-off value than needed for the immunity checkpoint inhibitors for 2 patients to administer: 5,9 mut/MB (primary tumor), 9,2 mut/MB (metastasis), while in 2 other patients the TMB has level above the threshold – 10,9 mut/MB (primary tumor) and 48,5 mut/MB (relapse metastasis), respectively. Conclusion: this paper presents the initial experience of estimation of the TMB level in children with HCC. In our case series report, the level allowing the prescription of immunotherapy (>10 mut/MB) was observed in 2 patients. Further research on a larger cohort of patients is useful to assess the role of mutational burden in disease prediction and effectiveness of immunotherapy.