Targeting FGFRs by pemigatinib induces G1 phase cell cycle arrest, cellular stress and upregulation of tumor suppressor microRNAs.

Background: Fibroblast growth factor receptor (FGFR) gene family alterations are found in several cancers, indicating their importance as potential therapeutic targets. The FGFR-tyrosine kinase inhibitor (TKI) pemigatinib has been introduced in the treatment of advanced cholangiocarcinoma and more recently for relapsed or refractory myeloid/lymphoid neoplasms with FGFR2 and FGFR1 rearrangements, respectively. Several clinical trials are currently investigating the possible combination of pemigatinib with immunotherapy. In this study, we analyzed the biological and molecular effects of pemigatinib on different cancer cell models (lung, bladder, and gastric), which are currently objective of clinical trial investigations.

Methods: NCI-H1581 lung, KATO III gastric and RT-112 bladder cancer cell lines were evaluated for FGFR expression by qRT-PCR and Western blot. Cell lines were treated with Pem and then characterized for cell proliferation, apoptosis, production of intracellular reactive oxygen species (ROS), and induction of senescence. The expression of microRNAs with tumor suppressor functions was analyzed by qRT-PCR, while modulation of the proteins coded by their target genes was evaluated by Western blot and mRNA. Descriptive statistics was used to analyze the various data and student's t test to compare the analysis of two groups.

Results: Pemigatinib exposure triggered distinct signaling pathways and reduced the proliferative ability of all cancer cells, inducing G1 phase cell cycle arrest and strong intracellular stress resulting in ROS production, senescence and apoptosis. Pemigatinib treatment also caused the upregulation of microRNAs (miR-133b, miR-139, miR-186, miR-195) with tumor suppressor functions, along with the downregulation of validated protein targets with oncogenic roles (c-Myc, c-MET, CDK6, EGFR).

Conclusions: These results contribute to clarifying the biological effects and molecular mechanisms mediated by the anti-FGFR TKI pemigatinib in distinct tumor settings and support its exploitation for combined therapies.