Abstract 4307
Background
Oncogenic activation of the receptor tyrosine kinase (RTK) RET via point mutation or genomic rearrangement has been identified in multiple cancers, including medullary and papillary thyroid cancers, and non-small cell lung cancer (NSCLC). Two multi-kinase RET inhibitors vandetanib and cabozantinib have been approved for thyroid cancer. Current investigational RET inhibitors BLU-667 and LOXO-292 have demonstrated efficacy in RET aberrant NSCLC and thyroid cancers. Multiple resistance mutations have been reported from preclinical studies, including the gatekeeper mutation V804L to cabozantinib and solvent front mutations (SFMs) G810A/S to vandetanib. Given that current TKIs often lead to resistance, TPX-0046, a next generation RET inhibitor that is structurally differentiated and potent against various mutations, especially SFMs, was designed.
Methods
A series of macrocyclic RET inhibitors were rationally designed and characterized in RET-related biological assays. TPX-0046 was further evaluated in RET-driven tumor models in vivo.
Results
TPX-0046 is a potent and selective next-generation RET/SRC inhibitor with a small and rigid macrocyclic structure that is structurally differentiated from current RET inhibitors. In enzymatic assays, TPX-0046 demonstrated low nanomolar potency against WT and many mutated RETs, as well as SRC, and is VEGFR2-sparing. TPX-0046 potently inhibited RET phosphorylation and cell proliferation in in-house engineered Ba/F3 KIF5B-RET, TT, and LC2/ad cells with IC50s of approximately 1 nM. TPX-0046 is potent against the SFM G810R in Ba/F3 cell proliferation assay with a mean IC50 of 17 nM, whereas comparable proxy molecules for BLU-667 and LOXO-292 have IC50s >500 nM. TPX-0046 demonstrated marked anti-tumor efficacy in vivo in multiple RET-driven cancer cell-derived and patient-derived xenograft tumor models.
Conclusions
TPX-0046 is a novel next generation RET/SRC inhibitor with favorable pharmaceutical properties and possesses potent in vitro and in vivo activity against diverse RET alterations, including the SFM G810R. The novel macrocyclic structure may provide opportunities to overcome treatment resistance from current RET inhibitors. TPX-0046 is currently in IND-enabling studies.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Turning Point Therapeutics, Inc.
Funding
Turning Point Therapeutics, Inc.
Disclosure
E. Rogers: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. D. Zhai: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. W. Deng: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. X. Zhang: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. D. Lee: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. J. Ung: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. J. Whitten: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. H. Zhang: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. J. Liu: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. T. Hu: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. H. Zhuang: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. Y. Lu: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. Z. Huang: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. A. Graber: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. Z. Zimmerman: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. R. Xin: Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics, Inc. J..J. Cui: Leadership role, Travel / Accommodation / Expenses, Shareholder / Stockholder / Stock options, Full / Part-time employment: Turning Point Therapeutics. All other authors have declared no conflicts of interest.
Resources from the same session
1269 - One-year follow-up results of eribulin for soft-tissue sarcoma including rare subtypes in a real-world observational study in Japan
Presenter: Shunji Takahashi
Session: Poster Display session 1
Resources:
Abstract
2868 - Prevalence of chemotherapy use and its impact on overall survival in patients with bone- and soft tissue sarcomas -A population-based analysis of 3746 patients
Presenter: Herbert Loong
Session: Poster Display session 1
Resources:
Abstract
3042 - Clinical course and therapeutic management of classical and endemic Kaposi’s Sarcoma (C/E KS)
Presenter: Lina Benajiba
Session: Poster Display session 1
Resources:
Abstract
3141 - The final outcomes of study on combined therapy of adult patients with localized synovial sarcoma
Presenter: Katarzyna Kozak
Session: Poster Display session 1
Resources:
Abstract
5449 - Real-world Outcomes of Patients with Locally Advanced or Metastatic Epithelioid Sarcoma
Presenter: Mrinal Gounder
Session: Poster Display session 1
Resources:
Abstract
4465 - SAKK 57/16 Nab-Paclitaxel And Gemcitabine in soft tissue sarcoma (NAPAGE): results from the phase I part of a phase I/II trial
Presenter: Antonia Digklia
Session: Poster Display session 1
Resources:
Abstract
5013 - Outcome of 98 patients with epithelioid sarcoma treated in curative intent: a retrospective study from the French Sarcoma Group (GSF-GETO)
Presenter: Maud Pedrono
Session: Poster Display session 1
Resources:
Abstract
5614 - Comparison of filgrastim and pegfilgrastim prophylaxis in sarcoma patients receiving highly myelosuppressive chemotherapy.
Presenter: Paolo Tarantino
Session: Poster Display session 1
Resources:
Abstract
1033 - Access to clinical trials for soft tissue sarcoma patients in Western and Eastern Europe
Presenter: Vasilii Ostafiichuk
Session: Poster Display session 1
Resources:
Abstract
4094 - Treatment outcomes for adult patients with localized osteosarcoma treated with chemotherapy without methotrexate
Presenter: Marília Silva
Session: Poster Display session 1
Resources:
Abstract