FGFR2 and neoplasm: Prolonged treatment of SNU16 tumour cells in vitro and SNU16 xenograft tumours in vivo with infigratinib resulted in tumour cell stasis for a period of 1–2 weeks, followed by acquired resistance to infigratinib and reinitiation of tumour growth concomitant with increased FGFR2 amplifications on ecDNA (Fig. 4f and Extended Data Fig. 10a–c).