Tumor-derived cell-free DNA (cfDNA) has biomarker potential; therefore, this study aimed to identify cfDNA in the aqueous humor (AH) of retinoblastoma eyes and correlate somatic chromosomal copy-number alterations (SCNA) with clinical outcomes, specifically eye salvage. AH was extracted via paracentesis during intravitreal injection of chemotherapy or enucleation. Shallow whole-genome sequencing was performed using isolated cfDNA to assess for highly recurrent SCNAs in retinoblastoma including gain of 1q, 2p, 6p, loss of 13q, 16q, and focal MYCN amplification. Sixty-three clinical specimens of AH from 29 eyes of 26 patients were evaluated; 13 eyes were enucleated and 16 were salvaged (e.g., saved). The presence of detectable SCNAs was 92% in enucleated eyes versus 38% in salvaged eyes (P = 0.006). Gain of chromosome 6p was the most common SCNA found in 77% of enucleated eyes, compared with 25% of salvaged eyes (P = 0.0092), and associated with a 10-fold increased odds of enucleation (OR, 10; 95% CI, 1.8–55.6). The median amplitude of 6p gain was 1.47 in enucleated versus 1.07 in salvaged eyes (P = 0.001). The presence of AH SCNAs was correlated retrospectively with eye salvage. The probability of ocular salvage was higher in eyes without detectable SCNAs in the AH (P = 0.0028), specifically 6p gain. This is the first study to correlate clinical outcomes with SCNAs in the AH from retinoblastoma eyes, as such these findings indicate that 6p gain in the aqueous humor is a potential prognostic biomarker for poor clinical response to therapy. Implications: The correlation of clinical outcomes and SCNAs in the AH identified in the current study requires prospective studies to validate these finding before SCNAs, like 6p gain, can be used to predict clinical outcomes at diagnosis. Mol Cancer Res; 16(11); 1701–12. ©2018 AACR.

Abstract

Bi-directional crosstalk between the tumor and the tumor microenvironment (TME) has been shown to increase the rate of tumor evolution and to play a key role in neoplastic progression, therapeutic resistance, and a patient’s overall survival. Here, we set out to use a comprehensive liquid-biopsy analysis to study cancer and specific TME cells in circulation and their association with disease status. Cytokeratin+, CD45- circulating rare cells (CRCs) from nine breast and four prostate cancer patients were characterized through morphometrics, single-cell copy number analysis, and targeted multiplexed proteomics to delineate cancer cell lineage from other rare cells originating in the TME. We show that we can detect epithelial circulating tumor cells (EPI.CTC), CTCs undergoing epithelial-to-mesenchymal transition (EMT.CTC) and circulating endothelial cells (CECs) using a universal rare event detection platform (HDSCA). Longitudinal analysis of an index patient finds that CTCs are present at the time of disease progression, while CECs are predominately present at the time of stable disease. In a small cohort of prostate and breast cancer patients, we find high inter-patient and temporal intra-patient variability in the expression of tissue specific markers such as ER, HER2, AR, PSA and PSMA and EpCAM. Our study stresses the importance of the multi-omic characterization of circulating rare cells in patients with breast and prostate carcinomas, specifically highlighting overlapping and cell type defining proteo-genomic characteristics of CTCs and CECs.

Metastatic breast cancer (mBC) patients have a high risk of progression and face poor prognosis overall, with about one third (34%) surviving five years or more. In rare instances (2–4% of cases) patients with mBC have ERBB2 (HER2) activating mutations but are ERBB2 non-amplified. Neratinib is a potent, irreversible inhibitor that binds HER2 and inhibits downstream signaling. We used the previously validated high-definition single cell assay (HDSCA) workflow to investigate the clinical significance of the liquid biopsy in ERBB2 mutant, non-amplified, post-menopausal mBC patients starting neratinib and fulvestrant combination therapy. Characterization with a comprehensive liquid biopsy methodology (HDSCA) included genomic analysis of both the cell-free DNA (cfDNA) and single circulating tumor cells (CTCs) to monitor tumor evolution and identify potential mutational variants unique to the patient’s clinical response. A limited series of five sequentially enrolled patients presented here were from the MutHER (https://www.clinicaltrials.gov, NCT01670877) or SUMMIT (https://www.clinicaltrials.gov, NCT01953926) trials. Patients had an average of 5.4 lines of therapy before enrollment, variable hormone receptor status, and ERBB2 mutations at diagnosis and during treatment. CTC enumeration alone was not sufficient to predict clinical response. Treatment pressure was shown to lead to an observable change in CTC morphology and genomic instability (GI), suggesting these parameters may inform prognosis. Single cell copy number alteration (CNA) analysis indicated that the persistence or development of a clonal population of CTCs during treatment was associated with a worse response. Hierarchical clustering analysis of the single cells across all patients and timepoints identified distinct aberrant regions shared among patients, comprised of 26 genes that are similarly affected and may be related to drug resistance. Additionally, the genomic analysis of the cfDNA, identified new mutations in ERBB2, PIK3CA, and TP53 that arose likely due to treatment pressure in a patient with poor response, further providing insights on the dynamics of the cancer genome over the course of therapy. The data presented in this small cohort study demonstrates the feasibility of real-time molecular profiling of the cellular and acellular fractions of the liquid biopsy using the HDSCA methodology. Additional studies are necessary to determine the potential use of morphometric and genomic analysis as a prognostic tool to advance personalized oncology.

Purpose: Metastatic hormone receptor (HR)-positive, HER2-negative breast cancer is an important cause of cancer mortality. Endocrine treatment with or without additional targeted therapies has been the mainstay of treatment. This trial was designed to evaluate the combination of fulvestrant plus everolimus versus fulvestrant, everolimus, and anastrozole compared with fulvestrant alone in the first-line treatment of advanced HR-positive, HER2-negative breast cancer. Patients and Methods: This randomized placebo-controlled trial included postmenopausal women with HR-positive, HER2-negative advanced breast cancer who had received no prior systemic therapy for metastatic disease. Participants were randomized to one of three treatment arms and the primary outcome was progression-free survival (PFS), comparing combinations of fulvestrant and everolimus with or without anastrozole with fulvestrant alone. Circulating tumor cells (CTC), as measured with two different methods, and circulating tumor DNA (ctDNA) were evaluated serially prior to treatment and the beginning of the second cycle of therapy. Results: Due in part to changes in clinical practice, the study was closed after accruing only 37 participants. There was no evidence that everolimus-containing combination treatment improved PFS or overall survival relative to fulvestrant alone. When modeled continuously, an association was observed of baseline CTC and ctDNA with poorer survival. Conclusions: Although power of the study was limited, the findings were unable to support the routine use of everolimus combination endocrine therapy in the first-line treatment of advanced hormone-sensitive breast cancer. Prognostic impact of baseline ctDNA and copy-number variations in CTC was demonstrated.

The chief goal of the Blood Profiling Atlas in Cancer (BloodPAC) consortium is to promote collaborative efforts that support the development and implementation of liquid biopsy tests. Here, we report the results of a pilot study conducted by three BloodPAC members that aimed to demonstrate a multisite liquid biopsy testing framework using longitudinal blood specimens from 38 patients with metastatic breast cancer. Three laboratories receiving identical samples from two clinical sites each applied a different targeted sequencing platform to analyze mutations in cell-free DNA (cfDNA). The resulting mutational profiles reflected common breast cancer alterations, including clinically actionable mutations for 40% of hormone- receptor-positive patients. In 12 genes with shared target regions across sequencing panels, perfect inter-assay concordance was also observed for mutations detected above the lowest common assay limit of detection. Whole-genome copy number profiling of cfDNA and circulating tumor cells (CTCs) further revealed marked heterogeneity in copy number alterations and cfDNA tumor fractions across patients. Additionally, comparison of tumor fraction and CTC abundance demonstrated the complementary nature of cfDNA and CTC analyses. Overall, the framework described in this study may serve as a resource for future trials aiming to identify multimodal liquid biopsy biomarkers to guide clinical care.