Association between 21-gene-assay and detection of disseminated tumor cells in patients with early breast cancer: results from the IRMA trial

PURPOSE

Disseminated tumor cells (DTCs) in the bone marrow (BM) are known to be of prognostic value for patients with early breast cancer (EBC). In addition to histopathological features, multigene expression assays, such as the commercially available 21-gene Breast Recurrence Score® assay, have been validated for evaluating prognosis and making decisions concerning adjuvant treatment in EBC. In a previous retrospective study from our group, the 21-gene assay was shown to be associated with DTC-detection. A secondary endpoint of the prospective IRMA trial was to evaluate the association between Recurrence Score® (RS) result and tumor cell dissemination in patients with EBC.

METHODS

DTC-status and RS result were assessed in patients with ER-positive/HER2-negative EBC with 0-3 pathologic lymph nodes who underwent primary surgical treatment at the Department for Women's Health of Tuebingen University, Germany.

RESULTS

Patients with a high RS result (≥ 26) were more frequently DTC-positive (22.6%) than patients with a low RS result (8.6%, p = 0.034). The odds for DTC-positivity increased with rising RS values (p = 0.047).

CONCLUSION

We therefore confirm that a high genomic risk is associated with tumor cell dissemination into the BM. Further trials are needed to investigate whether therapeutic decisions could be further individualized by combining DTC-status and prognostic gene signature testing.

RANK pathway in cancer: underlying resistance and therapeutic approaches

Cancer remains one of the deadliest diseases despite advances in treatment. Metastatic cancers are the leading cause of death for advanced cancer patients. Those with advanced cancer with osteolytic-type bone metastases have a significantly lower quality of life. A novel treatment plan is needed now more than ever for breast cancer patients with bone metastases. There are shreds of evidence that cancer cells in the bloodstream interact with the bone microenvironment and that this interaction is a contributing component to breast cancer progression. Preventing any stage of this cycle can result in anti-metastasis effects. Since RANKL interacts with its receptor RANK and plays an important role in the vicious cycle, it has proven to be a successful therapeutic target in cancer treatment. As a result, we have presented a complete overview of the RANK pathway in cancer and discussed RANK signaling and tumor microenvironment, and potential therapeutic approaches in this review.

Circulating erythroblast abnormality associated with systemic pathologies may indicate bone marrow damage

Background:

The circulating rare cell population is diverse and rich in diagnostic information. Its characterization and clinical exploitation by cell-based liquid biopsy is an ongoing research task. Bone marrow is one of the major contributors to the peripheral blood rare cell population and, consequently, determines individual rare cell profiles thus depending on bone marrow health status. Bone marrow damage has been associated with aggressive or late-stage systemic diseases and egress of various bone marrow cells into the blood circulation. The association of quantity and heterogeneity of circulating erythroblast with bone marrow damage is of particular interest.

Methods:

Circulating CD71^high/CD45-/Hoechst^high blast cells from healthy, noncancer- and cancer-afflicted donors were enriched by CD45 depletion and analyzed by immunofluorescence microscopy.

Results:

A new finding of aberrant and mitotic circulating erythroid-like cells that appear similar across blood donors afflicted with various systemic pathologies is reported. Further presented is a classification of said erythroblast-like cells in nine subcategories according to morphological differences between phenotypically similar cells.

Conclusion:

Aberrant and mitotic bone marrow-derived rare circulating erythroid-like cells can be detected in the blood of afflicted individuals but not in healthy donors, suggesting the cause of bone marrow damage.

Evaluation of disseminated tumor cells and circulating tumor cells in patients with breast cancer receiving adjuvant zoledronic acid

We evaluated disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) in patients with stage I-III breast cancer with >4 MM/mL DTC at baseline who received adjuvant zoledronic acid (ZOL). ZOL was administered every 4 weeks for 24 months, and patients underwent bone marrow aspiration at baseline, and 12 and 24 months of ZOL. Complete DTC response (<4 DTC/mL), serial CTCs, survival, recurrence, and toxicity were determined. Forty-five patients received ZOL. Median baseline DTC was 13.3/mL. Significant reduction in median DTC occurred from baseline to 12 months, and 24 months. Complete DTC response was seen in 32% at 12 months, and 26% at 24 months. Nine patients developed recurrence. Baseline DTC > 30/mL and CTC > 0.8/mL were significantly associated with recurrence and death. Serial reduction in DTCs occurred. Higher baseline DTC > 30/mL and CTC > 0.8/mL correlated with recurrence and death.

Disseminated tumour cells from the bone marrow of early breast cancer patients: Results from an international pooled analysis

PURPOSE

Presence of disseminated tumour cells (DTCs) in the bone marrow (BM) has been described as a surrogate of residual disease in patients with early breast cancer (EBC). PADDY (Pooled Analysis of DTC Detection in Early Breast Cancer) is a large international analysis of pooled data that aimed to assess the prognostic impact of DTCs in patients with EBC.

EXPERIMENTAL DESIGN

Individual patient data were collected from 11 centres. Patients with EBC and available follow-up data in whom BM sampling was performed at the time of primary diagnosis before receiving any anticancer treatment were eligible. DTCs were identified by antibody staining against epithelial cytokeratins. Multivariate Cox regression was used to compare the survival of DTC-positive versus DTC-negative patients.

RESULTS

In total, 10,307 patients were included. Of these, 2814 (27.3%) were DTC-positive. DTC detection was associated with higher tumour grade, larger tumour size, nodal positivity, oestrogen receptor and progesterone receptor negativity, and HER2 positivity (all p < 0.001). Multivariate analyses showed that DTC detection was an independent prognostic marker for overall survival, disease-free survival and distant disease-free survival with hazard ratios (HR) and 95% confidence intervals (CI) of 1.23 (95% CI: 1.06-1.43, p = 0.006), 1.30 (95% CI: 1.12-1.52, p < 0.001) and 1.30 (95% CI: 1.08-1.56, p = 0.006), respectively. There was no association between locoregional relapse-free survival and DTC detection (HR 1.21; 95% CI 0.68-2.16; p = 0.512).

CONCLUSIONS

DTCs in the BM represent an independent prognostic marker in patients with EBC. The heterogeneous metastasis-initiating potential of DTCs is consistent with the concept of cancer dormancy.

The Role of the RANKL/RANK Axis in the Prevention and Treatment of Breast Cancer with Immune Checkpoint Inhibitors and Anti-RANKL

The receptor activator of nuclear factor-κB (RANK) and the RANK ligand (RANKL) were reported in the regulation of osteoclast differentiation/activation and bone homeostasis. Additionally, the RANKL/RANK axis is a significant mediator of progesterone-driven mammary epithelial cell proliferation, potentially contributing to breast cancer initiation and progression. Moreover, several studies supported the synergistic effect of RANK and epidermal growth factor receptor (EGFR) and described RANK's involvement in epidermal growth factor receptor 2 (ERBB2)-positive carcinogenesis. Consequently, anti-RANKL treatment has been proposed as a new approach to preventing and treating breast cancer and metastases. Recently, RANKL/RANK signaling pathway inhibition has been shown to modulate the immune environment and enhance the efficacy of anti-CTLA-4 and anti-PD-1 monoclonal antibodies against solid tumors. Clinical and experimental trials have emerged evaluating RANKL inhibition as an enhancer of the immune response, rendering resistant tumors responsive to immune therapies. Trials evaluating the combinatorial effect of immune checkpoint inhibitors and anti-RANKL treatment in double-positive (RANK+/ERBB2+) patients are encouraging.

Molecular Interplay between Dormant Bone Marrow-Resident Cells (BMRCs) and CTCs in Breast Cancer

Despite widespread knowledge that bone marrow-resident breast cancer cells (BMRCs) affect tumor progression, signaling mechanisms of BMRCs implicated in maintaining long-term dormancy have not been characterized. To overcome these hurdles, we developed a new experimental model of clinical dormancy employing patient-isolated Circulating Tumor Cells (de novo CTCs) and their injection in xenografts with subsequent tumor monitoring and CTC characterization (ex vivo CTCs). We hypothesized that significant distinctions exist between signaling pathways of bone marrow-homing vs metastasis-competent CTCs upon transplantation in xenografts. Comparative transcriptomic analyses of ex vivo vs de novo CTCs identified increased mTOR signaling—a critical pathway frequently dysregulated in breast cancer and implicated in cell survival and dormancy—with contrasting actions by its two complementary arms (mTORC2/mTORC1). Heightened mTORC2 downstream targets augmented quiescent CTCs (Ki67−/RBL2+ cells) in paired breast cancer tissues, along with high mTORC2 activity in solitary BMRCs and tissue-resident CTCs. Further, shRNA mediated the knockdown of RICTOR, an essential component of mTORC2, and augmented Ki67/PCNA biomarker expression and proliferation. Collectively, these findings suggest that the balance between mTORC1 vs mTORC2 signaling regulates CTC-associated mitotic and/or dormancy characteristics.

Genomic and expression profiling reveal molecular heterogeneity of disseminated tumor cells in bone marrow of early breast cancer

Detection of disseminated tumor cells (DTCs) in bone marrow is an established negative prognostic factor. We isolated small pools of (~20) EPCAM-positive DTCs from early breast cancer patients for genomic profiling. Genome-wide copy number profiles of DTC pools (n = 45) appeared less aberrant than the corresponding primary tumors (PT, n = 16). PIK3CA mutations were detected in 26% of DTC pools (n = 53), none of them were shared with matched PTs. Expression profiling of DTC pools (n = 30) confirmed the upregulation of EPCAM expression and certain oncogenes (e.g., MYC and CCNE1), as well as the absence of hematopoietic features. Two expression subtypes were observed: (1) luminal with dual epithelial-mesenchymal properties (high ESR1 and VIM/CAV1 expression), and (2) basal-like with proliferative/stem cell-like phenotype (low ESR1 and high MKI67/ALDH1A1 expression). We observed high discordance between ESR1 (40%) and ERRB2 (43%) expression in DTC pools vs. the clinical ER and HER2 status of the corresponding primary tumors, suggesting plasticity of biomarker status during dissemination to the bone marrow. Comparison of expression profiles of DTC pools with available data from circulating tumor cells (CTCs) of metastatic breast cancer patients revealed gene expression signatures in DTCs that were unique from those of CTCs. For example, ALDH1A1, CAV1, and VIM were upregulated in DTC pools relative to CTCs. Taken together, analysis of pooled DTCs revealed molecular heterogeneity, possible genetic divergence from corresponding primary tumor, and two distinct subpopulations. Validation in larger cohorts is needed to confirm the presence of these molecular subtypes and to evaluate their biological and clinical significance.

Circulating Tumor Cells Dynamics in Pancreatic Adenocarcinoma Correlate With Disease Status: Results of the Prospective CLUSTER Study

OBJECTIVES

Previous retrospective studies demonstrated that circulating tumor cells (CTCs) subtypes correlate with overall survival in patients with pancreatic ductal adenocarcinoma (PDAC). Herein, we report results of a prospective observational study on CTCs dynamics to assess their clinical significance.

METHODS

The CLUSTER study is a prospective longitudinal study on PDAC CTCs dynamics (NCT02974764). Multiple peripheral blood samples were collected from 200 consecutively enrolled patients with presumed PDAC diagnosis. CTCs were isolated and characterized by immunofluorescence.

RESULTS

Two major CTCs subtypes were identified in PDAC patients: epithelial CTCs (eCTCs) and epithelial/mesenchymal CTCs (mCTCs). Patients who received neoadjuvant chemotherapy had significantly lower total CTCs (tCTCs, P = 0.007), eCTCs (P = 0.007), and mCTCs (P = 0.034), compared with untreated patients eligible for upfront resection. Surgical resection of the primary tumor resulted in significant reduction, but not disappearance, of CTCs burden across all cell subtypes (P < 0.001). In multivariable logistic regression analysis, preoperative numbers of all CTCs subpopulations were the only predictors of early recurrence within 12 months from surgery in both chemo-naive and post-neoadjuvant patients (odds ratio 5.9 to 11.0). Alterations in CTCs were also observed longitudinally, before disease recurrence. A risk assessment score based on the difference of tCTCs increase accurately identified disease recurrence within the next 2 months, with an accuracy of 75% and 84% for chemo-naive and post-neoadjuvant patients, respectively.

CONCLUSION

We report novel findings regarding CTCs from a large prospective cohort of PDAC patients. CTCs dynamics reflect progression of disease and response to treatment, providing important information on clinical outcomes, not available by current tumor markers and imaging.

Tumor biomarker conversion between primary and metastatic breast cancer: mRNA assessment and its concordance with immunohistochemistry

Biomarker changes between primary (PT) and metastatic tumor (MT) site may be significant in individualizing treatment strategies and can result from actual clonal evolution, biomarker conversion, or technical limitations of diagnostic tests. This study explored biomarker conversion during breast cancer (BC) progression in 67 patients with different tumor subtypes and metastatic sites via mRNA quantification and subsequently analyzed the concordance between real-time qPCR and immunohistochemistry (IHC). Immunostaining for estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki-67 was performed on formalin-fixed, paraffin-embedded PT and MT tissue sections. RT-qPCR was performed using a multiplex RT-qPCR kit for ESR1, PGR, ERBB2, and MKI67 and the reference genes B2M and CALM2. Subsequent measurement of tumor biomarker mRNA expression to detect conversion revealed significant decreases in ESR1 and PGR mRNA and MKI67 upregulation (all p < 0.001) in MT compared to PT of all tumor subtypes and ERBB2 upregulation in MT from triple-negative PT patients (p = 0.023). Furthermore, ERBB2 mRNA was upregulated in MT brain biopsies, particularly those from triple-negative PTs (p = 0.023). High concordance between RT-qPCR and IHC was observed for ER/ESR1 (81%(κ 0.51) in PT and 84%(κ 0.34) in MT, PR/PGR (70%(κ 0.10) in PT and 78% (κ -0.32) in MT), and for HER2/ERBB2 (100% in PT and 89% in MT). Discordance between mRNA biomarker assessments of PT and MT resulting from receptor conversion calls for dynamic monitoring of BC tumor biomarkers. Overall, RT-qPCR assessment of BC target genes and their mRNA expression is highly concordant with IHC protein analysis in both primary and metastatic tumor.