Chemotherapy-induced activation of caspase-1 and IL-1α release by cancer cells remotely skews myelopoiesis to drive pro tumorigenic systemic neutrophil-dominant inflammation.

While chemotherapy-induced tumor cell death is known to modulate the local immune landscape, its systemic impact on distant bone marrow-a site essential for immune cell maturation-remains underexplored. Here, we show that gemcitabine chemotherapy induces inflammatory caspase-1-dependent pyroptosis in epithelial cancer cells (epiCaspase-1). Despite its inflammatory nature, epiCaspase-1-mediated cell death is non-immunogenic. Clinically, elevated expression of an epiCaspase-1 gene signature correlates with worse patient outcomes. Mechanistically, epiCaspase-1 triggers the noncanonical release of IL-1α through NINJ1 lytic pores, remotely skewing bone marrow hematopoiesis towards granulocyte-monocyte progenitors and mature neutrophil output. This systemic reprogramming elevates the neutrophil-to-lymphocyte ratio (NLR) in both peripheral blood and the local tumor microenvironment. Pharmacological inhibition of caspase-1 and IL-1α disrupts this cascade, normalizes hematopoiesis, and recalibrates NLR by promoting intratumoral CD8+ T cell infiltration and activation, ultimately enhancing chemotherapeutic efficacy. These findings challenge the assumption that inflammatory pyroptosis is inherently immunogenic; instead, it can reshape systemic immune landscape towards a neutrophil-dominant inflammation in the chemotherapy context.