Targeting ID2 to augment doxorubicin antitumor efficacy and enhance antibacterial defense without neutropenia.

This study identifies and characterizes ID2-iNeu, a novel antagonist of inhibitor of differentiation-2 (ID2), which exhibits dual bioactivities in promoting neutrophil differentiation and potentiating antitumor efficacy while ameliorating chemotherapy-induced neutropenia. Surface plasmon resonance (SPR) analysis verified the specific binding of ID2-iNeu to human ID2 protein. In vivo experiments in C57BL/6 mice demonstrated that ID2-iNeu markedly elevated neutrophil counts in peripheral blood and spleen, a phenotypic effect not observed for the well-established ID inhibitors AGX51 and AK778-XXMU. In a murine peritonitis model, ID2-iNeu improved bacterial clearance more efficiency, which was closely correlated with the increased abundance of neutrophils. In the B16 melanoma xenograft model, ID2-iNeu exerted potent antitumor activity and synergistically enhanced the therapeutic efficacy of doxorubicin (ADM). Notably, single-agent ADM treatment significantly reduced peripheral neutrophil levels, whereas combinatorial administration with ID2-iNeu effectively reversed ADM-induced neutropenia without exacerbating ADM-associated cardiotoxicity. Bone marrow RNA-sequencing analysis revealed that ID2-iNeu globally remodels the transcriptional profile of hematopoietic differentiation, modulating core signaling pathways (including IGF, PDGF, and Hippo cascades) and key transcription factor families (bHLH, Homeobox, and zf-C2H2), thereby facilitating neutrophil lineage commitment. Molecular docking simulations further revealed that a unique cation-π interaction formed between ID2-iNeu and the Lys58 residue of ID2 protein, which accounts for its distinct functional properties, distinguishing it from the other two ID-targeting compounds AGX51 and AK778-XXMU. Collectively, these findings demonstrate that ID2-iNeu serves as a promising therapeutic candidate for simultaneously alleviating chemotherapy-induced neutropenia and augmenting antitumor therapeutic responses.