1
|
Casadevall D, Hernandez-Prat A, Garc A-Alonso S, Arpi-Llucia O, Menendez S, Qin M, Guardia C, Morancho B, Sanchez-Mart N FJ, Zazo S, Gavilan E, Sabbaghi M, Eroles P, Cejalvo JM, Lluch A, Rojo F, Pandiella A, Rovira A, Albanell J. mTOR inhibition and trastuzumab-emtansine (T-DM1) in HER2-positive breast cancer. Mol Cancer Res 2022; 20:1108-1121. [PMID: 35348729 DOI: 10.1158/1541-7786.mcr-21-0545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 02/06/2022] [Accepted: 03/23/2022] [Indexed: 12/09/2022]
Abstract
In patients with trastuzumab-resistant HER2-positive breast cancer, the combination of everolimus (mTORC1 inhibitor) with trastuzumab failed to show a clinically significant benefit. However, the combination of mTOR inhibition and the antibody-drug conjugate (ADC) trastuzumab-emtansine (T-DM1) remains unexplored. We tested T-DM1 plus everolimus in a broad panel of HER2-positive breast cancer cell lines. The combination was superior to T-DM1 alone in four cell lines (HCC1954, SKBR3, EFM192A, and MDA-MB-36) and in two cultures from primary tumor cells derived from HER2-positive patient-derived xenografts (PDX), but not in BT474 cells. In the trastuzumab-resistant HCC1954 cell line, we characterized the effects of the combination using TAK-228 (mTORC1 and 2 inhibitor) and knockdown of the different mTOR complex components. T-DM1 did not affect mTOR downstream signaling nor induct autophagy. Importantly, mTOR inhibition increased intracellular T-DM1 levels, leading to increased lysosomal accumulation of the compound. The increased efficacy of mTOR inhibition plus T-DM1 was abrogated by lysosome inhibitors (chloroquine and bafilomycin A1). Our experiments suggest that BT474 are less sensitive to T-DM1 due to lack of optimal lysosomal processing and intrinsic resistance to the DM1 moiety. Finally, we performed several in vivo experiments that corroborated the superior activity of T-DM1 and everolimus in HCC1954 and PDX-derived mouse models. In summary, everolimus in combination with T-DM1 showed strong antitumor effects in HER2-positive breast cancer, both in vitro and in vivo. This effect might be related, at least partially, to mTOR-dependent lysosomal processing of T-DM1, a finding that might apply to other ADCs that require lysosomal processing. Implications: Inhibition of mTOR increases the anti-tumor activity of T-DM1, supporting that the combination of mTOR inhibitors and antibody-drug conjugates warrants clinical evaluation in patients with HER2-positive breast cancer.
Collapse
Affiliation(s)
| | | | | | - Oriol Arpi-Llucia
- IMIM (Institut Hospital del Mar d'Investigacions M�diques), Barcelona, Barcelona, Spain
| | | | - Mengjuan Qin
- Hospital del Mar Research Institute (IMIM), Barcelona, Spain
| | - Cristina Guardia
- Institut Hospital del Mar d'Investigacions Mèdiques, Barcelona, Barcelona, Spain
| | | | | | - Sandra Zazo
- IIS-Fundaci�n Jim�nez D�az-CIBERONC, UAM, Madrid, Spain
| | | | | | - Pilar Eroles
- INCLIVA Biomedical Research Institute - University of Valencia, Spain. CIBERONC, Valencia, Valencia, Spain
| | - Juan Miguel Cejalvo
- Biomedical Health Research Institute INCLIVA, University of Valencia, Valencia, Spain
| | - Ana Lluch
- University of Valencia - Biomedical Research Institute INCLIVA-Hospital Cl�nico de Valencia-CIBERONC, Valencia, Valencia, Spain
| | - Federico Rojo
- IIS-Fundaci�n Jim�nez D�az-CIBERONC, UAM, Madrid, Spain
| | - Atanasio Pandiella
- Centro de Investigaci�n del C�ncer, CIBERONC and IBSAL, Salamanca, Spain
| | | | - Joan Albanell
- Hospital Del Mar Medical Research Instiiute, Barcelona, Spain
| |
Collapse
|