V Subbiah1, T Shen2, S S Terzyan3, X Liu2, X Hu2, K P Patel4, M Hu5, M Cabanillas5, A Behrang6, F Meric-Bernstam7, P T T Vo8, B H M Mooers9, J Wu10. 1. Department of Investigational Cancer Therapeutics, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, USA. Electronic address: vsubbiah@mdanderson.org. 2. Peggy and Charles Stephenson Cancer Center, Oklahoma City, USA; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, USA. 3. Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA; Laboratory of Biomolecular Structure and Function, University of Oklahoma Health Sciences Center, Oklahoma City, USA. 4. Molecular Diagnostics Laboratory, Division of Diagnostic Imaging, the University of Texas MD Anderson Cancer Center, Houston, USA. 5. Endocrine and Neoplasia, Division of Diagnostic Imaging, the University of Texas MD Anderson Cancer Center, Houston, USA. 6. Musculoskeletal Imaging, Division of Diagnostic Imaging, the University of Texas MD Anderson Cancer Center, Houston, USA. 7. Department of Investigational Cancer Therapeutics, Division of Cancer Medicine, the University of Texas MD Anderson Cancer Center, Houston, USA. 8. Peggy and Charles Stephenson Cancer Center, Oklahoma City, USA. 9. Peggy and Charles Stephenson Cancer Center, Oklahoma City, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA; Laboratory of Biomolecular Structure and Function, University of Oklahoma Health Sciences Center, Oklahoma City, USA. Electronic address: blaine-mooers@ouhsc.edu. 10. Peggy and Charles Stephenson Cancer Center, Oklahoma City, USA; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, USA. Electronic address: jie-wu@ouhsc.edu.
Abstract
BACKGROUND: Selpercatinib (LOXO-292) and pralsetinib (BLU-667) are highly potent RET-selective protein tyrosine kinase inhibitors (TKIs) for treating advanced RET-altered thyroid cancers and non-small-cell lung cancer (NSCLC). It is critical to analyze RET mutants resistant to these drugs and unravel the molecular basis to improve patient outcomes. PATIENTS AND METHODS: Cell-free DNAs (cfDNAs) were analyzed in a RET-mutant medullary thyroid cancer (MTC) patient and a CCDC6-RET fusion NSCLC patient who had dramatic response to selpercatinib and later developed resistance. Selpercatinib-resistant RET mutants were identified and cross-profiled with pralsetinib in cell cultures. Crystal structures of RET-selpercatinib and RET-pralsetinib complexes were determined based on high-resolution diffraction data collected with synchrotron radiation. RESULTS: RETG810C/S mutations at the solvent front and RETY806C/N mutation at the hinge region were found in cfDNAs of an MTC patient with RETM918T/V804M/L, who initially responded to selpercatinib and developed resistance. RETG810C mutant was detected in cfDNAs of a CCDC6-RET-fusion NSCLC patient who developed acquired resistance to selpercatinib. Five RET kinase domain mutations at three non-gatekeeper residues were identified from 39 selpercatinib-resistant cell lines. All five selpercatinib-resistant RET mutants were cross-resistant to pralsetinib. X-ray crystal structures of the RET-selpercatinib and RET-pralsetinib complexes reveal that, unlike other TKIs, these two RET TKIs anchor one end in the front cleft and wrap around the gate wall to access the back cleft. CONCLUSIONS: RET mutations at the solvent front and the hinge are resistant to both drugs. Selpercatinib and pralsetinib use an unconventional mode to bind RET that avoids the interference from gatekeeper mutations but is vulnerable to non-gatekeeper mutations.
BACKGROUND:Selpercatinib (LOXO-292) and pralsetinib (BLU-667) are highly potent RET-selective protein tyrosine kinase inhibitors (TKIs) for treating advanced RET-altered thyroid cancers and non-small-cell lung cancer (NSCLC). It is critical to analyze RET mutants resistant to these drugs and unravel the molecular basis to improve patient outcomes. PATIENTS AND METHODS: Cell-free DNAs (cfDNAs) were analyzed in a RET-mutant medullary thyroid cancer (MTC) patient and a CCDC6-RET fusion NSCLCpatient who had dramatic response to selpercatinib and later developed resistance. Selpercatinib-resistant RET mutants were identified and cross-profiled with pralsetinib in cell cultures. Crystal structures of RET-selpercatinib and RET-pralsetinib complexes were determined based on high-resolution diffraction data collected with synchrotron radiation. RESULTS:RETG810C/S mutations at the solvent front and RETY806C/N mutation at the hinge region were found in cfDNAs of an MTC patient with RETM918T/V804M/L, who initially responded to selpercatinib and developed resistance. RETG810C mutant was detected in cfDNAs of a CCDC6-RET-fusion NSCLCpatient who developed acquired resistance to selpercatinib. Five RET kinase domain mutations at three non-gatekeeper residues were identified from 39 selpercatinib-resistant cell lines. All five selpercatinib-resistant RET mutants were cross-resistant to pralsetinib. X-ray crystal structures of the RET-selpercatinib and RET-pralsetinib complexes reveal that, unlike other TKIs, these two RET TKIs anchor one end in the front cleft and wrap around the gate wall to access the back cleft. CONCLUSIONS:RET mutations at the solvent front and the hinge are resistant to both drugs. Selpercatinib and pralsetinib use an unconventional mode to bind RET that avoids the interference from gatekeeper mutations but is vulnerable to non-gatekeeper mutations.
Authors: Jacob J Adashek; Aakash P Desai; Alexander Y Andreev-Drakhlin; Jason Roszik; Gilbert J Cote; Vivek Subbiah Journal: Mol Cancer Ther Date: 2021-09-06 Impact factor: 6.261
Authors: V Subbiah; T Shen; M Tetzlaff; A Weissferdt; L A Byers; T Cascone; A Behrang; F Meric-Bernstam; B H M Mooers; S M Rothenberg; K Ebata; J Wu Journal: Ann Oncol Date: 2021-02-20 Impact factor: 51.769