Agnieszka Dąbkowska, Martyna Janowska, Agata Pastorczak, Krzysztof Domka, Zuzanna Nowicka, Zuzanna Urbanska, Weronika Zając, Mikołaj Bugajewski, Julia Grzybowska, Pola Pruchniak, Klaudyna Fidyt, Wojciech Fendler, Jason Taslim, Nicholas T Crump, Alexey Ushmorov, Elzbieta Patkowska, Malgorzata Firczuk
B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is characterized by impaired B-cell maturation and poor prognosis in relapsed/refractory (R/R) cases. While CD20-targeted immunotherapies offer clinical benefit, their efficacy is limited by low and heterogeneous CD20 expression on BCP-ALL cells. In this study, we demonstrate that overexpression of wild-type IKZF1, a tumor suppressor frequently mutated in high-risk BCP-ALL, upregulates CD20 and promotes leukemic B cell maturation. Using a transcriptional mimicry approach, we identified mTORC1 inhibitors as compounds showing similarity to selected IKZF1-induced transcriptional signatures, including convergence on B-cell maturation and induction of CD20 expression both in vitro and in vivo. mTORC1 inhibition enhanced the antitumor efficacy of anti-CD20 monoclonal antibodies and promoted B-lineage antigen expression, while downregulating immature markers. Mechanistically, CD20 upregulation was mediated via the AKT-FOXO1 axis, with AKT phosphorylation being essential for this effect. Importantly, this phenotypic shift was observed in BCP-ALL models with IKZF1 deletions, highlighting the relevance to high-risk disease. Our findings support the use of mTORC1 inhibitors to sensitize BCP-ALL cells to CD20-directed immunotherapies and provide a strong rationale for their clinical evaluation as adjuncts to anti-CD20 immunotherapy in BCP-ALL.