Puppet masters of B‐cell progenitor acute lymphoblastic leukemia: The preB cell receptor and the interleukin 7 receptor α

Abstract

B‐cell progenitor acute lymphoblastic leukemia (BCP‐ALL) is enriched for a preB cell phenotype, hinting at a specific vulnerability of this cell stage. Two signaling pathways via the preB cell receptor (preBCR) and the interleukin 7 receptor α (IL‐7Rα) chain govern the balance between differentiation and proliferation at this stage and both receptor pathways are routinely altered in human BCP‐ALL. Here, we review the immunobiology of both the preBCR as well as the IL‐7Rα and analyze the human BCP‐ALL spectrum in the light of these signaling complexes. Finally, we present a terminology for preBCR signaling modules that distinguishes a pro‐proliferative “phase‐I” module from a pro‐differentiative “phase‐II” module. This terminology might serve as a framework to better address shared oncogenic mechanics of preB cell stage BCP‐ALL.