Caveolae-Mediated Endocytosis as a Novel Mechanism of Resistance to Trastuzumab Emtansine (T-DM1)

• Published in: Molecular cancer therapeutics 2018-01, Vol.17 (1), p.243-253
• Main Authors: Sung, Matthew, Tan, Xingzhi, Lu, Bingwen, Golas, Jonathan, Hosselet, Christine, Wang, Fang, Tylaska, Laurie, King, Lindsay, Zhou, Dahui, Dushin, Russell, Myers, Jeremy S, Rosfjord, Edward, Lucas, Judy, Gerber, Hans-Peter, Loganzo, Frank
• Format: Article
• Language: English
• Subjects: Animal models; Animals; Antineoplastic Agents, Immunological - pharmacology; Antineoplastic Agents, Immunological - therapeutic use; Biomarkers; Biotechnology; Breast cancer; Cancer; Caveolae; Caveolin; Caveolin-1; Cell culture; Drug resistance; Drug Resistance, Neoplasm; Endocytosis; Endocytosis - drug effects; ErbB-2 protein; Female; Humans; Immunotherapy; Intracellular; Male; MDR1 protein; Metastases; Mice; Molecular modelling; Monoclonal antibodies; P-Glycoprotein; Payloads; Protein transport; Proteins; Targeted cancer therapy; Trastuzumab; Trastuzumab - pharmacology; Trastuzumab - therapeutic use; Tumors
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-17-0403

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC) that has demonstrated clinical benefit for patients with HER2 metastatic breast cancer; however, its clinical activity is limited by inherent or acquired drug resistance. The molecular mechanisms that drive clinical resistance to T-DM1, especially in HER2 tumors, are not well understood. We used HER2 cell lines to develop models of T-DM1 resistance using a cyclical dosing schema in which cells received T-DM1 in an "on-off" routine until a T-DM1-resistant population was generated. T-DM1-resistant N87 cells (N87-TM) were cross-resistant to a panel of trastuzumab-ADCs (T-ADCs) with non-cleavable-linked auristatins. N87-TM cells do not have a decrease in HER2 protein levels or an increase in drug transporter protein (e.g., MDR1) expression compared with parental N87 cells. Intriguingly, T-ADCs using auristatin payloads attached via an enzymatically cleavable linker overcome T-DM1 resistance in N87-TM cells. Importantly, N87-TM cells implanted into athymic mice formed T-DM1 refractory tumors that remain sensitive to T-ADCs with cleavable-linked auristatin payloads. Comparative proteomic profiling suggested enrichment in proteins that mediate caveolae formation and endocytosis in the N87-TM cells. Indeed, N87-TM cells internalize T-ADCs into intracellular caveolin-1 (CAV1)-positive puncta and alter their trafficking to the lysosome compared with N87 cells. T-DM1 colocalization into intracellular CAV1-positive puncta correlated with reduced response to T-DM1 in a panel of HER2 cell lines. Together, these data suggest that caveolae-mediated endocytosis of T-DM1 may serve as a novel predictive biomarker for patient response to T-DM1. .