Extracellular vesicles and PD-L1 suppress macrophages, inducing therapy resistance in TP53-deficient B-cell malignancies

Elena Izquierdo, Daniela Vorholt, Stuart Blakemore, Benedict Sackey, Janica L. Nolte, Verena Barbarino, Jan Schmitz, Nadine Nickel, Daniel Bachurski, Liudmila Lobastova, Milos Nikolic, Michael Michalik, Reinhild Brinker, Olaf Merkel, Marek Franitza, Theodoros Georgomanolis, René Neuhaus, Maximilian Koch, Niklas Nasada, Gero KnittelBjörn Chapuy, Nicole Ludwig, Eckart Meese, Lukas Frenzel, Hans Christian Reinhardt, Martin Peifer, Rocio Rebollido-Rios, Heiko Bruns, Marcus Krüger, Michael Hallek, Christian P. Pallasch

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Genetic alterations in the DNA damage response (DDR) pathway are a frequent mechanism of resistance to chemoimmunotherapy (CIT) in B-cell malignancies. We have previously shown that the synergy of CIT relies on secretory crosstalk elicited by chemotherapy between the tumor cells and macrophages. Here, we show that loss of multiple different members of the DDR pathway inhibits macrophage phagocytic capacity in vitro and in vivo. Particularly, loss of TP53 led to decreased phagocytic capacity ex vivo across multiple B-cell malignancies. We demonstrate via in vivo cyclophosphamide treatment using the Eμ-TCL1 mouse model that loss of macrophage phagocytic capacity in Tp53-deleted leukemia is driven by a significant downregulation of a phagocytic transcriptomic signature using small conditional RNA sequencing. By analyzing the tumor B-cell proteome, we identified a TP53-specific upregulation of proteins associated with extracellular vesicles (EVs). We abrogated EV biogenesis in tumor B-cells via clustered regularly interspaced short palindromic repeats (CRISPR)-knockout (KO) of RAB27A and confirmed that the EVs from TP53-deleted lymphoma cells were responsible for the reduced phagocytic capacity and the in vivo CIT resistance. Furthermore, we observed that TP53 loss led to an upregulation of both PD-L1 cell surface expression and secretion of EVs by lymphoma cells. Disruption of EV bound PD-L1 by anti–PD-L1 antibodies or PD-L1 CRISPR-KO improved macrophage phagocytic capacity and in vivo therapy response. Thus, we demonstrate enhanced EV release and increased PD-L1 expression in TP53-deficient B-cell lymphomas as novel mechanisms of macrophage function alteration in CIT resistance. This study indicates the use of checkpoint inhibition in the combination treatment of B-cell malignancies with TP53 loss.

Original languageEnglish
Pages (from-to)3617-3629
Number of pages13
Issue number25
StatePublished - 22 Jun 2022
Externally publishedYes


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