A secondary RET mutation in the activation loop conferring resistance to vandetanib

Abstract

Resistance to vandetanib, a type I RET kinase inhibitor, developed in a patient with metastatic lung adenocarcinoma harboring a CCDC6-RET fusion that initially exhibited a response to treatment. The resistant tumor acquired a secondary mutation resulting in a serine-to-phenylalanine substitution at codon 904 in the activation loop of the RET kinase domain. The S904F mutation confers resistance to vandetanib by increasing the ATP affinity and autophosphorylation activity of RET kinase. A reduced interaction with the drug is also observed in vitro for the S904F mutant by thermal shift assay. A crystal structure of the S904F mutant reveals a small hydrophobic core around F904 likely to enhance basal kinase activity by stabilizing an active conformer. Our findings indicate that missense mutations in the activation loop of the kinase domain are able to increase kinase activity and confer drug resistance through allosteric effects.

RET Solvent Front Mutations Mediate Acquired Resistance to Selective RET Inhibition in RET-Driven Malignancies

“…3C). In vitro experiments confirmed that selpercatinib, pralsetinib, cabozantinib, and vandetanib lost significant inhibitory activity against RET G810S, G810R, and G810C (although selpercatinib and pralsetinib maintained inhibitor activity against RET V804 gatekeeper and S904F mutations 19 in enzyme assays and cell-based assays (Table 1 and RET Solvent Front Residue G810 that direct inhibition of drug binding (rather than increased kinase activity) is most likely responsible for loss of inhibitory activity.…”

“…15,16 Although rare, RET mutation-mediated resistance to MKIs has been previously reported in single patients (e.g., RET V804M gatekeeper mutations and RET S904F), mechanisms underlying resistance to selective RET TKIs remain unknown. [17][18][19][20] Understanding these mechanisms is critical to enable the design of next-generation therapies that can overcome resistance.…”

Current and Future Molecular Testing in NSCLC, What Can We Expect from New Sequencing Technologies?

“…Carbozantinib and vandetanib were also tested in clinical trials; PFS and OS were 5 and 10 months, respectively. Recently, a resistance mutation ( RET p.Ser904Phe) was identified in a CCDC6-RET fusion tumor in a patient that developed secondary resistance to vandetanib suggesting that similar type of resistance mechanisms as for other targeted drugs can occur [ 78 ]. Specific drugs are expected soon with better effects [ 79 , 80 ].…”

Exploring ligand binding pathways on proteins using hypersound–accelerated molecular dynamics

“…Although molecular dynamics (MD) simulations enable atomic-level observations, they are limited to several microseconds on standard high-performance computers and are thus normally applicable only to relatively fast processes (2). Recently, the kinetics of slower protein interaction processes were explored through long MD simulations spanning timescales of tens of microseconds to milliseconds (3)(4)(5), which were achieved through the development of special-purpose supercomputers for high-speed simulations (e.g., ANTON (6)) and/or algorithms to aggregate many short simulations (e.g., Markov state models (MSMs) (7)).…”