Matthew Salzberg

The proto-oncogene Rearranged During Transfection (RET) encodes a receptor tyrosine kinase that is essential for neural, renal, and thyroid development. Pathogenic RET alterations, including mutations and fusions, drive oncogenesis, most notably medullary and papillary thyroid carcinomas and non-small cell lung cancer, by constitutively activating downstream RAS–MAPK, PI3K–AKT, and JAK–STAT signaling. Early multi-kinase inhibitors such as vandetanib and cabozantinib demonstrated modest efficacy with significant toxicity, whereas the selective RET inhibitors selpercatinib and pralsetinib have achieved improved response rates and tolerability. However, resistance remains a key clinical challenge, arising from secondary RET mutations and bypass signaling via MET or EGFR pathways. Continued investigation into next-generation inhibitors and rational combination therapies aims to overcome resistance and optimize treatment sequencing, advancing precision oncology for RET-altered malignancies. Nonetheless, resistance, driven by secondary mutations and bypass signaling, presents a major therapeutic challenge. Ongoing development of next-generation inhibitors and combination strategies aims to overcome resistance and improve patient outcomes.

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases that are involved in the regulation of cell proliferation, survival, and development. FGFR alterations including amplifications, fusions, rearrangements, and mutations can result in the downstream activation of tyrosine kinases, leading to tumor development. Targeting these FGFR alterations has shown to be effective in treating cholangiocarcinoma, urothelial carcinoma, and myeloid/lymphoid neoplasms, and there are currently four FGFR inhibitors approved by the Food and Drug Administration (FDA). There have been developments in multiple agents targeting the FGFR pathway, including selective FGFR inhibitors, ligand traps, monoclonal antibodies, and antibody–drug conjugates. However, most of these agents have variable and low responses, with some intolerable toxicities and acquired resistances. This review will summarize previous clinical experiences and current developments in agents targeting the FGFR pathway, and will also discuss future directions for FGFR-targeting agents.

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases that involve in regulation of cell proliferation, survival, and development. FGFR alterations including amplifications, fusions, rearrangements, and mutations can result downstream activation of tyrosine kinases leading to tumor development. Targeting those FGFR alterations has shown to be effective in cholangiocarcinoma, urothelial carcinoma, and myeloid/lymphoid neoplasms and there are currently four FGFR inhibitors approved by the Food and Drug Administration (FDA). There have been developments of multiple agents targeting FGFR pathway including selective FGFR inhibitors, ligand traps, monoclonal antibodies, and antibody drug conjugates. However, most of these agents have variable and low responses with some intolerable toxicities and acquired resistances. This review will summarize previous clinical experiences and current developments of agents targeting FGFR pathway and discuss future directions of FGFR targeting agents.