Technical validation of a new microfluidic device for enrichment of CTCs from large volumes of blood by using buffy coats to mimic diagnostic leukapheresis products

Diagnostic leukapheresis (DLA) enables to sample larger blood volumes and increases the detection of circulating tumor cells (CTC) significantly. Nevertheless, the high excess of white blood cells (WBC) of DLA products remains a major challenge for further downstream CTC enrichment and detection. To address this problem, we tested the performance of two label-free CTC technologies for processing DLA products. For the testing purposes, we established ficollized buffy coats (BC) with a WBC composition similar to patient-derived DLA products. The mimicking-DLA samples (with up to 400 × 106 WBCs) were spiked with three different tumor cell lines and processed with two versions of a spiral microfluidic chip for label-free CTC enrichment: the commercially available ClearCell FR1 biochip and a customized DLA biochip based on a similar enrichment principle, but designed for higher throughput of cells. While the samples processed with FR1 chip displayed with increasing cell load significantly higher WBC backgrounds and decreasing cell recovery, the recovery rates of the customized DLA chip were stable, even if challenged with up to 400 × 106 WBCs (corresponding to around 120 mL peripheral blood or 10% of a DLA product). These results indicate that the further up-scalable DLA biochip has potential to process complete DLA products from 2.5 L of peripheral blood in an affordable way to enable high-volume CTC-based liquid biopsies.

Abstract P3-01-12: Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients

Introduction: The enumeration of circulating tumor cells (CTCs) has been shown to be of prognostic relevance for neoadjuvant, adjuvant and metastatic setting of breast cancer in multiple clinical trials. Moreover, the serial determination of CTCs enables therapy monitoring in the metastatic setting. One major caveat is the low number of CTCs detected by established methods which limits the possibility for further evaluation including phenotyping and genotyping. Therefore, the clinical use of CTCs as liquid biopsy for making therapy decisions is still under discussion. Diagnostic leukapheresis (DLA) has been previously established by our research group and implemented in the workflow for isolation and detection of CTCs enabling a reliable detection of CTCs at high frequency. The aim of this clinical study was to assess the safety of leukapheresis in 39 patients with primary and metastatic breast cancer.

Methods: DLA was performed at least 1d before surgery or chemotherapy. A median blood volume of 2.7 L (range, 1.0 L–5.3 L) was processed. Citrate dextrose solution A was used for anticoagulation with ratios ranging from 11:1 to 24:1. Complete blood count as well as measuring blood pressure and heart rate was performed before start of DLA and immediately after DLA. CTCs were enumerated using the CellSearch system. DLA products containing a median number of 1,8x108 MNCs were processed.

Results: 41 patients were eligible for DLA. Only in two patients DLA could not be performed due to technical problems. Thirty-nine patients underwent leukapheresis. Twenty-six patients had non metastatic breast cancer. Thirteen patients were diagnosed with metastatic breast cancer. Severe adverse events including hypotension, nauseas, tingling e.g. resulting in interruption of apheresis were not observed. The DLA did not interfere with the start of chemotherapy or surgery. Complete blood count before and after DLA showed statistic significant but clinically irrelevant decrease in numbers of leukocytes, thrombocytes, hemoglobin and the percentage of hematocrit. In 11/21 DLA samples (52%) of patients with primary breast cancer CTCs were detected. Number of CTCs ranged from 1 to 51. In 11/13 DLA samples (85%) of patients with MBC CTCs were detected. Number of CTCs ranged from 1 to 2913.

Conclusion: Establishing a routine DLA protocol we demonstrated that this procedure is clinically safe and can be implemented into the clinical workflow of breast cancer patient care.

Citation Format: Fehm T, Meier-Stiegen F, Jaeger B, Reinhardt F, Naskou J, Franken A, Neubauer H, Driemel C, Ruckhaeberle E, Niederacher D, Fischer J, Stoecklein N. Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-12.

A novel microfluidic platform for size and deformability based separation and the subsequent molecular characterization of viable circulating tumor cells

Circulating tumor cells (CTCs) were introduced as biomarkers more than 10 years ago, but capture of viable CTCs at high purity from peripheral blood of cancer patients is still a major technical challenge. Here, we report a novel microfluidic platform designed for marker independent capture of CTCs. The Parsortix™ cell separation system provides size and deformability-based enrichment with automated staining for cell identification, and subsequent recovery (harvesting) of cells from the device. Using the Parsortix™ system, average cell capture inside the device ranged between 42% and 70%. Subsequent harvest of cells from the device ranged between 54% and 69% of cells captured. Most importantly, 99% of the isolated tumor cells were viable after processing in spiking experiments as well as after harvesting from patient samples and still functional for downstream molecular analysis as demonstrated by mRNA characterization and array-based comparative genomic hybridization. Analyzing clinical blood samples from metastatic (n = 20) and nonmetastatic (n = 6) cancer patients in parallel with CellSearch(®) system, we found that there was no statistically significant difference between the quantitative behavior of the two systems in this set of twenty six paired separations. In conclusion, the epitope independent Parsortix™ system enables the isolation of viable CTCs at a very high purity. Using this system, viable tumor cells are easily accessible and ready for molecular and functional analysis. The system's ability for enumeration and molecular characterization of EpCAM-negative CTCs will help to broaden research into the mechanisms of cancer as well as facilitating the use of CTCs as "liquid biopsies."

Losses at chromosome 4q are associated with poor survival in operable ductal pancreatic adenocarcinoma

Here we tested the prognostic impact of genomic alterations in operable localized pancreatic ductal adenocarcinoma (PDAC). Fifty-two formalin-fixed and paraffin-embedded primary PDAC were laser micro-dissected and were investigated by comparative genomic hybridization after whole genome amplification using an adapter-linker PCR. Chromosomal gains and losses were correlated to clinico-pathological parameters and clinical follow-up data. The most frequent aberration was loss on chromosome 17p (65%) while the most frequent gains were detected at 2q (41%) and 8q (41%), respectively. The concomitant occurrence of losses at 9p and 17p was found to be statistically significant. Higher rates of chromosomal losses were associated with a more advanced primary tumor stage and losses at 9p and 18q were significantly associated with presence of lymphatic metastasis (chi-square: p = 0.03, p = 0.05, respectively). Deletions on chromosome 4 were of prognostic significance for overall survival and tumor recurrence (Cox-multivariate analysis: p = 0.026 and p = 0.021, respectively). In conclusion our data suggest the common alterations at chromosome 8q, 9p, 17p and 18q as well as the prognostic relevant deletions on chromosome 4q as relevant for PDAC progression. Our comprehensive data from 52 PDAC should provide a basis for future studies with a higher resolution to discover the relevant genes located within the chromosomal aberrations identified.

The immune system in neuroendocrine tumors

During the last 30 years the incidence of neuroendocrine tumors has increased considerably and the overall 5-year survival rate has not changed substantially. Conventional therapeutic approaches appear to show an unsatisfactory effect in the more insidious forms of malignancies. Hence, attempts were made to direct the patient's own immune system against cancer by vaccinating against different tumor antigens. Up to date, only sporadic achievements were demonstrated in the majority cases of vaccination trials. One of the main hindrances to a successful vaccination comprises tumor-immune-escape mechanisms. This review focuses on the current knowledge concerning tumor immunoevasion strategies and the immune system in neuroendocrine tumors.

Global histone modification pattern predicts poor prognosis in organic hyperinsulinism

Here we tested whether global histone modifications predict survival in organic hyperinsulinism and whether global histone modification pattern can be used to distinguish benign from malignant primary insulinoma. A tissue microarray (TMA) was built, using samples from 63 patients with organic hyperinsulinism. The TMA was classified according to the WHO classification of 2004 [WHO 1A: benign insulinoma (wdPET); WHO 1B: unknown behavior (wdPETub); WHO 2/3: malignant insulinoma (wdPEC/pdPEC)]. The TMA consisted of tissue cores from islands of Langerhans, primary insulinomas, lymph node metastases, and hepatic metastases. Immunohistochemistry was performed on consecutive TMA slides with antibodies against H3K9Ac, H3K18Ac, H4K12Ac, H3K4diMe, and H4R3diMe. The Remmele immunoreactive scoring system was used to classify the staining. The IHC staining results were correlated to the WHO-classification of 2004 as well as to clinical follow-up data (mean: 107 months; range: 1-312 months). A nuclear staining pattern was observed for all antibodies directed against histone H3 and H4 acetylation/methylation sites. We observed significant differences in the distribution of the medians across all investigated tissue types (H3K9Ac, p=0.004; H3K18Ac, p=0.001; H4K12Ac, p=0.006; H4R3diMe, p=0.002) except for H3K4diMe (p=0.183). Correlation of the histone modification with the WHO-classification and clinical follow-up data, showed in the dichotomized groups ["low" (score 0-3), "moderate" (4-7) vs. "high" (≥8)] that patients with lower H3K18Ac levels ("low + moderate") had a significantly decreased relapse-free survival vs. patients with high H3K18Ac levels (p=0.038). The WHO classification and age were also of significant prognostic impact upon univariate analysis. A backwards Cox proportional hazards model revealed the independent prognostic effekt of H3K18Ac levels. Our data revealed low K18 acetylation levels of histone H3 as independent prognostic factor in organic hyperinsulinism. This result warrants validation with independent data sets of organic hyperinsulinism, but is in line with several previous studies in different cancer entities. The broad applicability of this potential biomarker might lead to standardized diagnostic tests in near future and may help to manage insulinoma patients more effectively.

The hematopoietic stem cell in chronic phase CML is characterized by a transcriptional profile resembling normal myeloid progenitor cells and reflecting loss of quiescence

We found that composition of cell subsets within the CD34+ cell population is markedly altered in chronic phase (CP) chronic myeloid leukemia (CML). Specifically, proportions and absolute cell counts of common myeloid progenitors (CMP) and megakaryocyte-erythrocyte progenitors (MEP) are significantly greater in comparison to normal bone marrow whereas absolute numbers of hematopoietic stem cells (HSC) are equal. To understand the basis for this, we performed gene expression profiling (Affymetrix HU-133A 2.0) of the distinct CD34+ cell subsets from six patients with CP CML and five healthy donors. Euclidean distance analysis revealed a remarkable transcriptional similarity between the CML patients' HSC and normal progenitors, especially CMP. CP CML HSC were transcriptionally more similar to their progeny than normal HSC to theirs, suggesting a more mature phenotype. Hence, the greatest differences between CP CML patients and normal donors were apparent in HSC including downregulation of genes encoding adhesion molecules, transcription factors, regulators of stem-cell fate and inhibitors of cell proliferation in CP CML. Impaired adhesive and migratory capacities were functionally corroborated by fibronectin detachment analysis and transwell assays, respectively. Based on our findings we propose a loss of quiescence of the CML HSC on detachment from the niche leading to expansion of myeloid progenitors.

Expression of 17-1A antigen and complement resistance factors CD55 and CD59 on liver metastasis in colorectal cancer

Despite radical surgery, the prognosis for colorectal cancer patients with liver metastases has not changed markedly. Furthermore, no standard adjuvant therapeutic regimen has been developed. Adjuvant therapy with monoclonal antibodies (e.g., against 17-1A), which has been shown to be effective in preventing metastatic relapse in patients with Dukes' C colorectal cancer, might be a promising approach for these patients. However, the cytotoxic effects of monoclonal antibodies can be blocked by coexpression of complement resistance factors that inhibit antibody-dependent complement-mediated cytotoxicity. We therefore analyzed immunohistochemically the expression of 17-1A and the membrane-bound complement resistance factors CD55 and CD59 on metastatic tumor cells in the livers of 71 patients with colorectal carcinoma who had undergone resection of their metastases with curative intent. In 67 (94%) of 71 patients, liver metastases with homogeneous expression of 17-1A was seen. Heterogeneous expression of 17-1A was seen in four patients (6%). Heterogeneous expression of CD55 or CD59 was observed in 8 (11%) of 71 patients and 4 (6%) of 71 patients, respectively. None of the patients showed homogeneous expression of either CD55 or CD59. All patients with CD55 or CD59 expression showed homogeneous 17-1A expression, whereas none of the four patients with heterogeneous 17-1A expression was positive for CD55 or CD59. Our data indicate that 17-1A is widely expressed on liver metastases of patients with colorectal carcinoma. Therefore patients with completely resected liver metastases might be suitable candidates for adjuvant therapy with and-17-1A antibody since only a few of these lesions showed coexpression of complement resistance factors.

Esophageal cancer: the mode of lymphatic tumor cell spread and its prognostic significance

PURPOSE

Data on skip metastases and their significance are lacking for esophageal cancer. This issue is important to determine the extent of lymphadenectomy for esophageal resection. In this study we examined the lymphatic spread in esophageal cancer by routine histopathology and by immunohistochemistry.

PATIENTS AND METHODS

A total of 1,584 resected lymph nodes were obtained from 86 patients with resected esophageal carcinoma and evaluated by routine histopathology. Additionally, frozen tissue sections of 540 lymph nodes classified as tumor-free by routine histopathology were screened for micrometastases by immunohistochemistry with the monoclonal antibody Ber-EP4. The lymph nodes were mapped according to the mapping scheme of the American Thoracic Society modified by Casson et al.

RESULTS

Forty-four patients (51%) had pN1 disease, and 61 patients (71%) harbored lymphatic micrometastases detected by immunohistochemistry. Skip metastases detected by routine histopathology were present in 34% of pN1 patients. Skipping of micrometastases detected by immunohistochemistry was found in 66%. The presence of micrometastases was associated with a significantly decreased relapse-free and overall survival (56.0 v 10.0 months and > 64 v 15 months, P <.0001 and P =.004, respectively). Cox regression analysis revealed the independent prognostic influence of micrometastases in lymph nodes. Lymph node skipping had no significant independent prognostic influence on survival.

CONCLUSION

Histopathologically and immunohistochemically detectable skip metastases are a frequent event in esophageal cancer. Only extensive lymph node sampling, in conjunction with immunohistochemical evaluation, will lead to accurate staging. An improved staging system is essential for more individualized adjuvant therapy.

Expression and prognostic significance of immunoregulatory molecules in esophageal cancer

Major histocompatibility complex molecules (HLA), the co-stimulatory molecule B7 and the intercellular adhesion molecule 1 (ICAM-1) are key molecules involved in T cell-mediated immune surveillance. We aimed at assessing the expression pattern of these immunoregulatory molecules on primary esophageal carcinomas and evaluating their prognostic significance. Representative samples of primary tumors were obtained from 53 patients who had undergone radical en bloc esophagectomy without residual tumor. Cryostat sections of these tumors were stained with monoclonal antibodies (MAbs) directed against either HLA class I, HLA class II, B7 or ICAM-1. The median follow-up was 19 months (range, 6-43). We found that HLA class I expression was deficient on 27 tumors, while a significant neo-expression of HLA class II, B7 and ICAM-1 (> or =25% positive tumor cells) was observed on 17, 29 and 25, tumors, respectively. Kaplan-Meier analyses revealed a significant beneficial influence on relapse-free survival for patients with tumors expressing HLA class I, HLA class II and B7. Cox's regression analyses demonstrated that co-expression of HLA class I and ICAM-1 was a significant and independent predictor of a reduced risk of developing tumor recurrence, whereas expression of ICAM-1 on HLA class I negative tumors was correlated with an increased risk of tumor relapse.

Expression and prognostic significance of immunoregulatory molecules in esophageal cancer

Major histocompatibility complex molecules (HLA), the co-stimulatory molecule B7 and the intercellular adhesion molecule 1 (ICAM-1) are key molecules involved in T cell-mediated immune surveillance. We aimed at assessing the expression pattern of these immunoregulatory molecules on primary esophageal carcinomas and evaluating their prognostic significance. Representative samples of primary tumors were obtained from 53 patients who had undergone radical en bloc esophagectomy without residual tumor. Cryostat sections of these tumors were stained with monoclonal antibodies (MAbs) directed against either HLA class I, HLA class II, B7 or ICAM-1. The median follow-up was 19 months (range, 6-43). We found that HLA class I expression was deficient on 27 tumors, while a significant neo-expression of HLA class II, B7 and ICAM-1 (> or =25% positive tumor cells) was observed on 17, 29 and 25, tumors, respectively. Kaplan-Meier analyses revealed a significant beneficial influence on relapse-free survival for patients with tumors expressing HLA class I, HLA class II and B7. Cox's regression analyses demonstrated that co-expression of HLA class I and ICAM-1 was a significant and independent predictor of a reduced risk of developing tumor recurrence, whereas expression of ICAM-1 on HLA class I negative tumors was correlated with an increased risk of tumor relapse.

Early lymphatic tumor cell dissemination in pancreatic cancer: frequency and prognostic significance

Tumor relapse occurs frequently in patients with ductal pancreatic head cancer despite the absence of residual tumor detectable at primary surgery. Therefore it has to be assumed that current tumor staging procedures fail to detect minimal amounts of disseminated tumor cells present in secondary organs, which might be the seed for subsequent metastatic relapse. We evaluated lymph nodes from 18 patients without overt metastases who had undergone radical tumor resection (R0 resection). Lymph nodes judged as "tumor-free" by routine histopathology were further examined for the presence of single tumor cells using immunohistochemistry with the antiepithelial monoclonal antibody Ber-EP4. Sixteen of 37 "tumor-free" lymph nodes (43.2%), obtained from 13 of 18 patients (72.2%), displayed Ber-EP4+ tumor cells. Twelve of these 18 patients presented at pT2 stage. Nine of 12 patients (75%) staged as pN0 had these cells. Two of six pN1 patients had no Ber-EP4+ in histopathologically tumor-free lymph nodes. Using multivariate Cox's regression analysis, the presence of Ber-EP4+ cells in "tumor-free" lymph nodes was an independent factor for a significantly reduced relapse-free survival (p = 0.006) and overall survival (p = 0.01). Remarkably, all patients who were restaged as lymph node negative by both histopathology and immunohistochemistry survived the observation period without recurrence. The frequent occurrence of disseminated tumor cells in patients with pancreatic cancer and their prognostic impact support the need for a refined staging system of excised lymph nodes, which should include immunohistochemical examination. Thus patients with a minimal residual tumor load who might benefit from an adjuvant therapy could be selected.

Expression and prognostic significance of HLA class I, ICAM-1, and tumor-infiltrating lymphocytes in esophageal cancer

Most solid malignancies show some degree of lymphoid infiltration suggesting a specific immunologic host vs. tumor reaction. Tumor-infiltrating lymphocytes (i.e., CD3 + T-lymphocyte subsets), the human leukocyte antigen (HLA) class I molecules, and the intercellular adhesion molecule-1 (ICAM-1) are key factors involved in T-cell-mediated immune surveillance. The present study was designed to assess the expression pattern of intratumoral lymphocyte infiltrates and their relationship to HLA class I and ICAM-1 expression with regard to primary esophageal carcinoma and to evaluate their prognostic influence. Representative samples of primary tumors were obtained from 55 patients who had undergone radical en bloc esophagectomy. Frozen sections of these tumors were stained with monoclonal antibodies directed against CD3 for the assessment of tumor-infiltrating lymphocytes, HLA class I, and ICAM-1. The mean postoperative observation period was 19.5 months (range 5 to 45 months). Lymphocyte infiltration was absent in four tumors (8%), whereas 31 tumors (64%) showed moderate and 13 (27%) showed strong infiltration. HLA class I expression was deficient in 24 tumors (45%). Coexpression of HLA class I and ICAM-1 was significantly associated with lymphocyte infiltration of the tumor. Kaplan-Meier analyses revealed a significant beneficial influence on relapse-free survival for patients with lymphocyte infiltration of primary tumors compared to those with no lymphocyte infiltration of tumors (median 4 months vs. 18 months; P <0.002) and for HLA class I+ tumors compared to HLA class I- tumors (median survival >18 months vs. 7 months; P = 0.0081). The present data support the hypothesis that T-cell-mediated immunity may influence the fate of patients with esophageal cancer.