Shaymaa Bahnassy

Background: Although anti-HER2 monoclonal antibody therapy with trastuzumab and pertuzumab is highly effective for HER2-positive breast cancer, co-expression of estrogen receptor (ER) significantly reduces pathologic complete response rates. Objective: We investigated how HER2-targeted inhibition affects HER2 cellular localization and ER genomic binding in ER-positive, HER2-positive breast cancer. Methods: We evaluated HER2 localization in a tissue microarray of treatment-naive patients. Using cellular fractionation, immunofluorescence, chromatin immunoprecipitation, and genome-wide profiling (CUT&RUN), we evaluated HER2 localization and ER genomic binding following acute anti-HER2 treatment and in models of treatment resistance. The treatment-induced ER-bound gene signature was assessed for associations with pathologic complete response and survival in breast cancer clinical cohorts. Results: In treatment-naive primary breast tumors, nuclear HER2 inversely correlated with ER levels. In cell models, treatment with trastuzumab and pertuzumab induced nuclear and chromatin accumulation of HER2. Concurrently, acute anti-HER2 treatment displaced ER from canonical estrogen response elements at classical target genes, yet genome-wide profiling revealed redistribution of ER binding toward non-canonical zinc finger motifs adjacent to pro-survival Wnt and RAGE pathway genes (FZD8, RELA). Expression of a drug-induced ER-bound gene signature was significantly higher in tumors of individuals who did not achieve pathologic complete response following neoadjuvant anti-HER2 therapy and significantly correlated with reduced distant metastasis-free survival in clinical cohorts. Conclusions: Anti-HER2 targeted therapy causes dynamic cistromic reprogramming of ER from classical estrogen pathways toward alternative pro-survival networks. These findings implicate ER redistribution as a possible mediator of resistance and highlight novel therapeutic targets in ER-positive, HER2-positive breast cancer.

PURPOSE: Current precision medicine (CPM) matches patients to therapies using traditional biomarkers, but inevitably resistance develops. Dynamic precision medicine (DPM) is a new evolutionary guided precision medicine (EGPM) approach undergoing translational development. It tracks intratumoral genetic heterogeneity and evolutionary dynamics, adapts as frequently as every 6 weeks, plans proactively for future resistance development, and incorporates multiple therapeutic agents. Simulations indicated DPM can significantly improve long-term survival and cure rates in a cohort of 3 million virtual patients representing a variety of clinical scenarios. Given the cost and invasiveness of monitoring subclones frequently, we sought to determine the value of a short DPM window of only two 6-week adaptations (moves). METHODS: In a new simulation, nearly 3 million virtual patients, differing in DPM input parameters of initial subclone compositions, drug sensitivities, and growth and mutational kinetics, were simulated as previously described. Each virtual patient was treated with CPM, DPM, and DPM for two moves followed by CPM. RESULTS: The first two DPM moves provide similar average benefit to a 5-year, 40-move sequence in the full virtual population. If the first two moves are identical for DPM and CPM, patients will not benefit from DPM (65% negative predictive value). A patient subset (20%) in which 2-move DPM and 40-move DPM provide closely similar outcomes has extraordinary predicted benefit (hazard ratio of DPM/CPM 0.03). CONCLUSION: The first two DPM moves provide most of the clinical benefit of DPM, reducing the duration required for subclone monitoring. This also leads to an evolutionary classifier selecting patients who will benefit: those in whom DPM and CPM recommendations differ early. These advances bring DPM (and potentially other EGPM approaches) closer to potential clinical testing.

Invasive Lobular Carcinoma (ILC) is a subtype of breast cancer characterized by distinct biological features, and limited glucose uptake coupled with increased reliance on amino acid and lipid metabolism. Our prior studies highlight the importance of glutamate as a key regulator of ILC tumor growth and therapeutic response. Here we examine the expression of four key proteins involved in glutamate transport and metabolism – SLC3A2, SLC7A11, GPX4, and GLUD1/2 – in a racially diverse cohort of 72 estrogen receptor-positive (ER+) ILC and 50 ER+ invasive ductal carcinoma, no special type (IDC/NST) patients with primary disease. All four proteins associate with increased tumor size in ILC, with three showing stronger associations in Black women, but not in IDC/NST. Among these three proteins in ILC, GLUD1/2 uniquely associates with ER expression in all women, while GLUD1/2 and SLC3A2 are enriched in hypertensive women. GLUD1/2 and GPX4 are upregulated in endocrine therapy-resistant ILC cell lines, and pharmacological inhibition of GLUD1 reduces ER protein levels and cell viability. Together, these findings support a potentially important role for glutamate metabolism in ILC and suggest GLUD1 and other glutamate-handling proteins as candidate targets for therapeutic intervention in ILC.

Mass spectrometry methods supplement

Metabolomics datasets and siRNA analyses

ILC tumor metabolic gene expression

BioID setup and proof-of-concept

ILC tumor metabolic gene expression

Mass spectrometry methods supplement

Supplementary File 2 from WNT4 Regulates Cellular Metabolism via Intracellular Activity at the Mitochondria in Breast and Gynecologic Cancers