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Novel human-derived RET fusion NSCLC cell lines have heterogeneous responses to RET inhibitors and differential regulation of downstream signaling

RET rearrangements occur in 1-2% of lung adenocarcinomas as well as other malignancies and are now established targets for tyrosine kinase inhibitors. We developed three novel RET-positive(RET+) patient-derived cancer cell lines, CUTO22(KIF5B-RET+), CUTO32(KIF5B-RET+) and CUTO42(EML4-RET+) to study RET signaling and response to therapy. We confirmed each of our cell lines express the RET fusion protein and assessed their sensitivity to RET inhibitors. We found that the CUTO22 and CUTO42 cell lines were sensitive to multiple RET inhibitors while the CUTO32 cell line was >10-fold more resistant to three RET inhibitors. We discovered that our RET+ cell lines had differential regulation of the MAPK and PI3K/AKT pathways. Following inhibition of RET, the CUTO42 cells had robust inhibition of pAKT, while CUTO22 and CUTO32 cells had sustained AKT activation. Next, we performed a drug screen which revealed that the CUTO32 cells were sensitive (<1nM IC50) to inhibition of two cell cycle-regulating proteins, PLK1 and Aurora kinase A. Finally, we show that two of these cell lines, CUTO32 and CUTO42, successfully establish xenografted tumors in nude mice. We demonstrated that the RET inhibitor BLU-667 was effective at inhibiting tumor growth in CUTO42 tumors, but had a much less profound effect in CUTO32 tumors, consistent with our in vitro experiments. These data highlight the utility of new RET+ models to elucidate differences in response to tyrosine kinase inhibitors and downstream signaling regulation. Our RET+ cell lines effectively recapitulate interpatient heterogeneity observed in response to RET inhibitors and reveal opportunities for alternative or combination therapies. Significance Statement We have derived and characterized three novel RET fusion non-small cell lung cancer cell lines and demonstrated that they have differential responses to RET inhibition as well as regulation of downstream signaling; an area that has previously been limited by a lack of diverse cell line modes with endogenous RET fusions. These data offer important insight into regulation of response to RET tyrosine kinase inhibitors and other potential therapeutic targets.

Related Products

Cat.No. Product Name Information Publications Customer Product Validation
S8716 Pralsetinib (BLU-667) Pralsetinib (BLU-667, CS 3009, Gavreto) is a highly potent and selective RET (c-RET) inhibitor with an IC50 of 0.4 nM for WT RET. It also demonstrates potent activity (IC50 0.4 nmol/L) against common oncogenic RET alterations, including RET (M918T). (3)

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