Identification of Novel Small Molecule Inhibitors of Oncogenic RET Kinase

Abstract

Oncogenic mutation of the RET receptor tyrosine kinase is observed in several human malignancies. Here, we describe three novel type II RET tyrosine kinase inhibitors (TKI), ALW-II-41-27, XMD15-44 and HG-6-63-01, that inhibit the cellular activity of oncogenic RET mutants at two digit nanomolar concentration. These three compounds shared a 3-trifluoromethyl-4-methylpiperazinephenyl pharmacophore that stabilizes the ‘DFG-out’ inactive conformation of RET activation loop. They blocked RET-mediated signaling and proliferation with an IC50 in the nM range in fibroblasts transformed by the RET/C634R and RET/M918T oncogenes. They also inhibited autophosphorylation of several additional oncogenic RET-derived point mutants and chimeric oncogenes. At a concentration of 10 nM, ALW-II-41-27, XMD15-44 and HG-6-63-01 inhibited RET kinase and signaling in human thyroid cancer cell lines carrying oncogenic RET alleles; they also inhibited proliferation of cancer, but not non-tumoral Nthy-ori-3-1, thyroid cells, with an IC50 in the nM range. The three compounds were capable of inhibiting the ‘gatekeeper’ V804M mutant which confers substantial resistance to established RET inhibitors. In conclusion, we have identified a type II TKI scaffold, shared by ALW-II-41-27, XMD15-44 and HG-6-63-01, that may be used as novel lead for the development of novel agents for the treatment of cancers harboring oncogenic activation of RET.

Targeting EphA2 impairs cell cycle progression and growth of basal-like/triple-negative breast cancers

“… 24 Studies from our laboratory using cell line and mouse models of non-small cell lung cancer confirmed EphA2 targeting. 22 , 23 A more recent study, however, reported that ALW-II-41-27 inhibits RET tyrosine kinase activity and function in RET-transformed fibroblasts, HEK293 cells, and in primary tumor cells and cell lines from human thyroid cancer, 25 raising the possibility that this inhibitor could impair TNBC growth in our models by targeting other kinases. Since no other group to our knowledge has tested the potential off-target effects in an EphA2-null model, we decided to test the impact of ALW-II-41-27 on EphA2-deficient C3-TAg tumor cells relative to NG-25 analog control.…”

New insights in the molecular signature of advanced medullary thyroid cancer: evidence of a bad outcome of cases with doubleRETmutations

“…The majority of TKIs tested until now are multitarget therapies14 15 26 but only a few of them are active against RET . Some new products with a high specificity for several oncogenic RET mutants and chimeric oncogenes have been recently reported,27 28 thus highlighting the necessity to screen for somatic RET mutations, possibly all MTC, or at least those presenting as advanced cases, which are potentially treatable with TKI.…”

Analysis of Cell-Free DNA from 32,989 Advanced Cancers Reveals Novel Co-occurring Activating RET Alterations and Oncogenic Signaling Pathway Aberrations

“…While these agents are nonspecific, they have been investigated in RETdriven NSCLC with response rates as high or higher than with chemotherapy, although lower than that of other oncogenetargeted therapies in NSCLC such as those for EGFR, ALK, ROS1, and BRAF V600E (24)(25)(26). Gatekeeper RET V804M/L mutations may be acquired after targeting of RET fusions with vandetanib or cabozantinib; however, their prevalence in a clinical setting is not known (27)(28)(29)(30). More selective RET inhibitors are showing promise in early-phase clinical trials in patients with RET-driven advanced solid tumors and also have activity against the V804 gatekeeper mutation (NCT03157128, NCT03037385, NCT01877811; refs.…”