It has been reported that FGFR kinase domain mutations and PIK3CA activation mutations contribute to erdafitinib acquired resistance in FGFR‐driven bladder cancers.[7] Furthermore, paracrine activation of the NRG1/HER3 axis mediated by adipocyte precursors can also promote resistance to erdafitinib rapidly.[38]  In contrast, our work uncovers a novel intrinsic resistance mechanism. The gene discussed is PIK3CA; the disease is urinary bladder cancer.