Authors: Mariela Cortés-López, Laura Schulz, Mihaela Enculescu, Claudia Paret, Bea Spiekermann, Mathieu Quesnel-Vallières, Manuel Torres-Diz, Sebastian Unic, Anke Busch, Anna Orekhova, Monika Kuban, Mikhail Mesitov, Miriam M. Mulorz, Rawan Shraim, Fridolin Kielisch, Jörg Faber, Yoseph Barash, Andrei Thomas-Tikhonenko, Kathi Zarnack, Stefan Legewie, Julian König
Published: 2022-09-22
DOI: 10.1038/s41467-022-31818-y
Source: Full article
AbstractFollowing CART-19 immunotherapy for B-cell acute lymphoblastic leukaemia (B-ALL), many patients relapse due to loss of the cognate CD19 epitope. Since epitope loss can be caused by aberrant CD19 exon 2 processing, we herein investigate the regulatory code that controls CD19 splicing. We combine high-throughput mutagenesis with mathematical modelling to quantitatively disentangle the effects of all mutations in the region comprising CD19 exons 1-3. Thereupon, we identify ~200 single point mutations that alter CD19 splicing and thus could predispose B-ALL patients to developing CART-19 resistance. Furthermore, we report almost 100 previously unknown splice isoforms that emerge from cryptic splice sites and likely encode non-functional CD19 proteins. We further identify cis-regulatory elements and trans-acting RNA-binding proteins that control CD19 splicing (e.g., PTBP1 and SF3B4) and validate that loss of these factors leads to pervasive CD19 mis-splicing. Our dataset represents a comprehensive resource for identifying predictive biomarkers for CART-19 therapy.