2. Academic Validation
  3. A bi-steric mTORC1-selective inhibitor overcomes drug resistance in breast cancer

A bi-steric mTORC1-selective inhibitor overcomes drug resistance in breast cancer

  • Oncogene. 2023 Jun 1. doi: 10.1038/s41388-023-02737-z.
Delong Meng 1,  Xin Zhao 1,  Yu Chi Yang 2,  Albertas Navickas 3 4 5 6 7,  Ciara Helland 2,  Hani Goodarzi 3 4 5 6,  Mallika Singh 2,  Sourav Bandyopadhyay 8 9 10
Affiliations

Affiliations

  • 1 Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
  • 2 Department of Biology, Revolution Medicines Inc., Redwood City, CA, USA.
  • 3 Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94158, USA.
  • 4 Department of Urology, University of California, San Francisco, San Francisco, CA, USA.
  • 5 Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA.
  • 6 Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA.
  • 7 Institut Curie, PSL Research University, CNRS UMR3348, INSERM U1278, Orsay, France.
  • 8 Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA. [email protected].
  • 9 Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA. [email protected].
  • 10 Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA. [email protected].
PMID: 37264081 DOI: 10.1038/s41388-023-02737-z
Abstract

Activation of the PI3K-mTOR pathway is central to breast Cancer pathogenesis including resistance to many targeted therapies. The mTOR kinase forms two distinct complexes, mTORC1 and mTORC2, and understanding which is required for the survival of malignant cells has been limited by tools to selectively and completely impair either subcomplex. To address this, we used RMC-6272, a bi-steric molecule with a rapamycin-like moiety linked to an mTOR active-site inhibitor that displays >25-fold selectivity for mTORC1 over mTORC2 substrates. Complete suppression of mTORC1 by RMC-6272 causes Apoptosis in ER+/HER2- breast Cancer cell lines, particularly in those that harbor mutations in PIK3CA or PTEN, due to inhibition of the rapamycin resistant, mTORC1 substrate 4EBP1 and reduction of the pro-survival protein MCL1. RMC-6272 reduced translation of ribosomal mRNAs, MYC target genes, and components of the CDK4/6 pathway, suggesting enhanced impairment of oncogenic pathways compared to the partial mTORC1 Inhibitor everolimus. RMC-6272 maintained efficacy in hormone therapy-resistant acquired cell lines and patient-derived xenografts (PDX), showed increased efficacy in CDK4/6 inhibitor treated acquired resistant cell lines versus their parental counterparts, and was efficacious in a PDX from a patient experiencing resistance to CDK4/6 inhibition. Bi-steric mTORC1-selective inhibition may be effective in overcoming multiple forms of therapy-resistance in ER+ breast cancers.

Figures
Products