Project description:Estrogen receptor positive (ER+) breast cancers that develop resistance to therapies that target the ER are the most common cause of breast cancer death. Beyond mutations in ER, which occur in 25-30% of patients treated with aromatase inhibitors (AIs), our understanding of clinical mechanisms of resistance to ER-directed therapies remains incomplete. We identified activating HER2 mutations in metastatic biopsies from eight patients with ER+ metastatic breast cancer who had developed resistance to ER-directed agents, including AIs, tamoxifen, and fulvestrant. Examination of treatment-naïve primary tumors in five patients revealed no evidence of pre-existing mutations in four of five patients, suggesting that these mutations were acquired under the selective pressure of ER-directed therapy. These mutations were mutually exclusive with ER mutations, suggesting a distinct mechanism of acquired resistance to ER-directed therapies. In vitro analysis confirmed that these mutations conferred estrogen independence. In addition, and in contrast to ER mutations, these mutations resulted in resistance to tamoxifen, fulvestrant, and the CDK4/6 inhibitor palbociclib. Resistance was overcome by combining ER-directed therapy with the irreversible HER2 kinase inhibitor neratinib, highlighting an effective treatment strategy in these patients.
Project description:Beyond acquired mutations in the estrogen receptor (ER), mechanisms of resistance to ER-directed therapies in ER+ breast cancer have not been clearly defined. We conducted a genome-scale functional screen spanning 10,135 genes to investigate genes whose overexpression confer resistance to selective estrogen receptor degraders. Pathway analysis of candidate resistance genes demonstrated that the FGFR, ERBB, insulin receptor, and MAPK pathways represented key modalities of resistance. In parallel, we performed whole exome sequencing in paired pre-treatment and post-resistance biopsies from 60 patients with ER+ metastatic breast cancer who had developed resistance to ER-targeted therapy. The FGFR pathway was altered via FGFR1, FGFR2, or FGF3/FGF4 amplifications or FGFR2 mutations in 24 (40%) of the post-resistance biopsies. In 12 of the 24 post-resistance tumors exhibiting FGFR/FGF alterations, these alterations were not detected in the corresponding pre-treatment tumors, suggesting that they were acquired or enriched under the selective pressure of ER-directed therapy. In vitro experiments in ER+ breast cancer cells confirmed that FGFR/FGF alterations led to fulvestrant resistance as well as cross-resistance to the CDK4/6 inhibitor palbociclib, through activation of the MAPK pathway. The resistance phenotypes were reversed by FGFR inhibitors and, to a lesser extent, MEK inhibitors, suggesting potential treatment strategies.
Project description:There is clinical need to predict sensitivity of metastatic hormone receptor-positive and HER2-negative (HR+/HER2-) breast cancer to endocrine therapy, and targeted RNA sequencing (RNAseq) offers diagnostic potential to measure both transcriptional activity and functional mutation. We developed the SET ER/PR index to measure gene expression microarray probe sets that were correlated with hormone receptors (ESR1 and PGR) and robust to pre-analytical and analytical influences. We tested SET ER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SETER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SET ER/PR index in metastatic samples predicted longer progression-free (PFS) and overall survival (OS) when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.534, 95% CI 0.299 to 0.955, p = 0.035; OS: HR 0.315, 95% CI 0.157 to 0.631, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1% to 98% of ESR1 transcripts (all had high SETER/PR index). A signature based on probe sets with good pre-analytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SET ER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript. We tested SET ER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SET ER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SET ER/PR index in metastatic samples predicted longer progression-free (PFS) and overall survival (OS) when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.485, 95% CI 0.265 to 0.889, p = 0.019; OS: HR 0.314, 95% CI 0.155 to 0.637, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1% to 98% of ESR1 transcripts (all had high SET ER/PR index). A signature based on probe sets with good pre-analytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SET ER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript.
Project description:Although the estrogen receptor (ER) positive variant of breast cancer is touted as the most indolent and favorable, the majority of breast cancer deaths are in fact from this subtype. There are several features of this category of breast cancers that likely account for this outcome. The first is that metastatic relapse can occur many years after initial diagnosis of primary disease. The second is that once the cancer cells awaken into full-blown metastatic disease, they are largely resistant to ER-directed therapies (i.e. hormonal therapy, HT). The third is that when metastases do occur, they are invariably in many locations. This observation suggests that these dormant/sleeping metastatic cells are “globally” awakened as if by a “systemic” infection. We suggest that these three processes be not only linked, but underlie the lethal features of metastatic disease. We hypothesized that mtDNA is necessary for the escape from therapy induced tumor dormancy of luminal breast cancer cells
Project description:There is clinical need to predict sensitivity of metastatic hormone receptor-positive and HER2-negative (HR+/HER2-) breast cancer to endocrine therapy, and targeted RNA sequencing (RNAseq) offers diagnostic potential to measure both transcriptional activity and functional mutation. We developed the SETER/PR index to measure gene expression microarray probe sets that were correlated with hormone receptors (ESR1 and PGR) and robust to pre-analytical and analytical influences. We tested SETER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SETER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SETER/PR index in metastatic samples predicted longer progression-free (PFS) and overall survival (OS) when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.534, 95% CI 0.299 to 0.955, p = 0.035; OS: HR 0.315, 95% CI 0.157 to 0.631, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1% to 98% of ESR1 transcripts (all had high SETER/PR index). A signature based on probe sets with good pre-analytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SETER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript.
Project description:Resistance to endocrine treatments and CDK4/6 inhibitors is considered a near-inevitability in most patients with estrogen receptor positive breast cancers (ER + BC). By genomic and metabolomics analyses of patients' tumours, metastasis-derived patient-derived xenografts (PDX) and isogenic cell lines we demonstrate that a fraction of metastatic ER + BC is highly reliant on oxidative phosphorylation (OXPHOS). Treatment by the OXPHOS inhibitor IACS-010759 strongly inhibits tumour growth in multiple endocrine and palbociclib resistant PDX. Mutations in the PIK3CA/AKT1 genes are significantly associated with response to IACS-010759. At the metabolic level, in vivo response to IACS-010759 is associated with decreased levels of metabolites of the glutathione, glycogen and pentose phosphate pathways in treated tumours. In vitro, endocrine and palbociclib resistant cells show increased OXPHOS dependency and increased ROS levels upon IACS-010759 treatment. Finally, in ER + BC patients, high expression of OXPHOS associated genes predict poor prognosis. In conclusion, these results identify OXPHOS as a promising target for treatment resistant ER + BC patients.
Project description:HT induces an OXPHOS metabolic editing of ER+ breast cancers, paradoxically establishing HT-driven self-renewal of dormant CD133hi/ERlo cells mediating metastatic progression, which is sensitive to dual targeted therapy In this study, we demonstrated that CD133hi cells can mediate HT resistance and metastatic progression. Using human luminal breast cancer cell lines we have developed an in vivo model of spontaneous metastatic disease recapitulating what is observed in patients. Combining in vivo and in vitro studies we identified a de-novo cancer stem cell population (CSCs) “CD133hi/ERlo/Notch3hi/IL6hi”, which are generated from non-CSCs via the sustained suppression of ER activity. We provide evidence that an ER-IL6-IL6R-CD133 loop is a mechanism mediating HT-resistance.