The Ontogeny and Vulnerabilities of Lapatinib Drug Tolerant Persisters [NPY1R]

Despite significant advances in HER2-targeted therapies, therapeutic resistance in HER2-positive (HER2+) breast cancer remains a significant clinical problem, especially in the metastatic setting. “Drug tolerant persisters” (DTPs), a sub-population of cancer cells that survive via reversible, non-genetic mechanisms, are implicated in resistance to tyrosine kinase inhibitors (TKIs) in several cancer models, but DTPs for HER2-targeted TKIs (e.g., lapatinib, neratinib, tucatinib) have not been characterized extensively. Here, we report that HER2+ER+ and HER2+ER- breast cancer lines give rise to distinct types of “lapatinib-DTPs,” characterized by different transcriptional programs and sensitivity to lapatinib/anti-estradiol combination. Lapatinib-DTPs from HER2+/ER+ cells rewire the PI3K/AKT/mTORC1 pathway via transcriptional induction of SGK3 to enable AKT-independent mTORC1 activation and survival. Lentiviral barcoding experiments, combined with single cell RNA-sequencing, suggest that HER2+ cells stochastically cycle through a cell state (“pre-DTP”) capable of transition to DTPs. Collectively, our results provide insight into DTP ontogeny and therapeutic vulnerabilities. mRNA profiles of NPY1R high vs. low BT474 breast cancer cells