Burkitt lymphoma (BL), an aggressive B-cell lymphoma, is most frequently associated with a chromosomal translocation t(8;14) that relocates the MYC oncogene near the IGH gene locus. Exploring translocation formation mechanisms and approaches to diminish the risk of their formation is a promising aim. We aimed to investigate the kinetics of t(8;14) accumulation in a cell culture and to assess how targeting different cellular pathways affects translocation frequency. Methods: CRISPR/Cas9 was used to generate double-strand breaks (DSBs) in the IGH and MYC gene loci in a human B-cell line. We evaluated the t(8;14) level 48 hours, two, three, four, five and six weeks after DSBs induction by qPCR [1]. We also analyzed the level of t(8;14) 48 hours after the simultaneous DSBs induction and addition of chemical inhibitors to cell medium. We used NU7026 (DNA-PKcs inhibitor, canonical NHEJ), L67 (Lig1/Lig3 inhibitor, alternative NHEJ), sodium azide (electron-transport chain inhibitor). Results: We found that acquiring t(8;14)does not provide any selective advantage in the overall cell population as the level of t(8;14) progressively declined after DSBs induction. This can be due to increased expression of MYC in cells with t(8;14), which is known to induce apoptosis via the p53 pathway [2]. When testing the effect of different drugs on translocation efficiency in our in vitro system, we found that sodium azide decreased the level of t(8;14), which can be explained by energy depletion, as DNA repair is an ATP-dependent pathway [3]. We also observed that L67 significantly decreased the level of t(8;14), while NU7026 significantly increased the level of t(8;14). Conclusions: We revealed that in vitro IGH-MYC translocation provides no selective advantage as the translocation is lost during long cell culturing. We also found that energy depletion and alternative NHEJ inhibition can decrease the level of t(8;14) translocations. We can thus conclude that translocations in our model are mainly due to alternative NHEJ. Funding: The work was supported by grants from Plan Cancer (ENVIBURKITT), ANRS and LNCC to YV. AS was supported by a fellowship form the Boehringer Ingelheim Fonds. References 1. Germini D, Bou Saada Y, Tsfasman T et al. A One-Step PCR-Based Assay to Evaluate the Efficiency and Precision of Genomic DNA-Editing Tools. Mol Ther Methods Clin Dev. 2017;5: 43–50. 2. Phesse TJ, Myant KB, Cole AM et al. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo. Cell Death Differ. 2014;21: 956–966. 3. Lu J, Sharma LK, Bai Y. Implications of mitochondrial DNA mutations and mitochondrial dysfunction in tumorigenesis. Cell Res. 2009;19: 802–815.