Kristina Aaltonen

Co-targeting of the PI3K pathway improves the response of BRCA1 deficient breast cancer cells to PARP1 inhibition

Although pre-clinical and clinical studies on PARP1 inhibitors, alone and in combination with DNA-damaging agents, show promising results, further ways to improve and broaden the scope of application of this therapeutic approach are warranted. To this end, we have investigated the possibility of improving the response of BRCA1 mutant breast cancer cells to PARP1 inhibition by co-targeting the PI3K pathway. Human breast cancer cell lines with or without the expression of BRCA1 and/or PTEN were treated with PARP1 and PI3K inhibitors as single agents and in combination. PARP1 inhibition induced DNA damage conferring a G2/M arrest and decrease in viability, paralleled by the induction of apoptosis. PI3K inhibition alone caused a G1 arrest and decreased cell growth. Most importantly, sequential combination of PARP and PI3K inhibitors interacted synergistically to significantly decrease growth compared to PARP inhibition alone. Global transcriptional profiling revealed that this decrease in growth was associated with down-regulation of macromolecule biosynthesis and the induction of apoptosis. Taken together, these results suggest an improved treatment strategy for BRCA1-mutant and possibly also triple-negative breast cancers with similar molecular defects.

Systemic Monocytic-MDSCs Are Generated from Monocytes and Correlate with Disease Progression in Breast Cancer Patients.

Myeloid-derived suppressor cells (MDSCs) are highly immunosuppressive myeloid cells, which increase in cancer patients. The molecular mechanism behind their generation and function is unclear. Whereas granulocytic-MDSCs correlate with poor overall survival in breast cancer, the presence and relevance of monocytic-MDSCs (Mo-MDSCs) is unknown. Here we report for the first time an enrichment of functional blood Mo-MDSCs in breast cancer patients before they acquire a typical Mo-MDSC surface phenotype. A clear population of Mo-MDSCs with the typical cell surface phenotype (CD14+HLA-DRlow/-CD86low/-CD80low/-CD163low/-) increased significantly first during disease progression and correlated to metastasis to lymph nodes and visceral organs. Furthermore, monocytes, comprising the Mo-MDSC population, from patients with metastatic breast cancer resemble the reprogrammed immunosuppressive monocytes in patients with severe infections, both by their surface and functional phenotype but also at their molecular gene expression profile. Our data suggest that monitoring the Mo-MDSC levels in breast cancer patients may represent a novel and simple biomarker for assessing disease progression.

Prognostic impact of circulating tumor cell apoptosis and clusters in serial blood samples from patients with metastatic breast cancer in a prospective observational cohort

BackgroundPresence of circulating tumor cells (CTCs) is a validated prognostic marker in metastatic breast cancer. Additional prognostic information may be obtained by morphologic characterization of CTCs. We explored whether apoptotic CTCs, CTC clusters and leukocytes attached to CTCs are associated with breast cancer subtype and prognosis at base-line (BL) and in follow-up (FU) blood samples in patients with metastatic breast cancer scheduled for first-line systemic treatment.MethodsPatients with a first metastatic breast cancer event were enrolled in a prospective observational study prior to therapy initiation and the CellSearch system (Janssen Diagnostics) was used for CTC enumeration and characterization. We enrolled patients (N = 52) with ≥5 CTC/7.5 ml blood at BL (median 45, range 5–668) and followed them with blood sampling for 6 months during therapy. CTCs were evaluated for apoptotic changes, CTC clusters (≥3 nuclei), and leukocytes associated with CTC (WBC-CTC, ≥1 CTC + ≥1 leukocytes) at all time-points by visual examination of the galleries generated by the CellTracks Analyzer.ResultsAt BL, patients with triple-negative and HER2-positive breast cancer had blood CTC clusters present more frequently than patients with hormone receptor-positive cancer (P = 0.010). No morphologic characteristics were associated with prognosis at BL, whereas patients with apoptotic CTCs or clusters in FU samples had worse prognosis compared to patients without these characteristics with respect to progression-free (PFS) and overall survival (OS) (log-rank test: P = 0.0012 or lower). Patients with apoptotic or clustered CTCs at any time-point had impaired prognosis in multivariable analyses adjusting for number of CTCs and other prognostic factors (apoptosis: HROS = 25, P < 0.001; cluster: HROS = 7.0, P = 0.006). The presence of WBC-CTCs was significantly associated with an inferior prognosis in terms of OS at 6 months in multivariable analysis.ConclusionsPatients with a continuous presence of apoptotic or clustered CTCs in FU samples after systemic therapy initiation had worse prognosis than patients without these CTC characteristics. In patients with ≥5 CTC/7.5 ml blood at BL, morphologic characterization of persistent CTCs could be an important prognostic marker during treatment, in addition to CTC enumeration alone.Clinical Trials (NCT01322893), registration date 21 March 2011

Laser capture microdissection (LCM) and whole genome amplification (WGA) of DNA from normal breast tissue --- optimization for genome wide array analyses

BackgroundLaser capture microdissection (LCM) can be applied to tissues where cells of interest are distinguishable from surrounding cell populations. Here, we have optimized LCM for fresh frozen normal breast tissue where large amounts of fat can cause problems during microdissection. Since the amount of DNA needed for genome wide analyses, such as single nucleotide polymorphism (SNP) arrays, is often greater than what can be obtained from the dissected tissue, we have compared three different whole genome amplification (WGA) kits for amplification of DNA from LCM material. In addition, the genome wide profiling methods commonly used today require extremely high DNA quality compared to PCR based techniques and DNA quality is thus critical for successful downstream analyses.FindingsWe found that by using FrameSlides without glass backing for LCM and treating the slides with acetone after staining, the problems caused by excessive fat could be significantly decreased. The amount of DNA obtained after extraction from LCM tissue was not sufficient for direct SNP array analysis in our material. However, the two WGA kits based on Phi29 polymerase technology (Repli-g® (Qiagen) and GenomiPhi (GE Healthcare)) gave relatively long amplification products, and amplified DNA from Repli-g® gave call rates in the subsequent SNP analysis close to those from non-amplified DNA. Furthermore, the quality of the input DNA for WGA was found to be essential for successful SNP array results and initial DNA fragmentation problems could be reduced by switching from a regular halogen lamp to a VIS-LED lamp during LCM.ConclusionsLCM must be optimized to work satisfactorily in difficult tissues. We describe a work flow for fresh frozen normal breast tissue where fat is inclined to cause problems if sample treatment is not adapted to this tissue. We also show that the Phi29-based Repli-g® WGA kit (Qiagen) is a feasible approach to amplify DNA of high quality prior to genome wide analyses such as SNP profiling.

Transurethral Bladder Tumor Resection Can Cause Seeding of Cancer Cells into the Bloodstream

PURPOSE Transurethral bladder tumor resection is the initial diagnostic procedure for bladder cancer. Hypothetically tumor resection could induce seeding of cancer cells into the circulation and subsequent metastatic disease. In this study we ascertain whether transurethral bladder tumor resection induces measurable seeding of cancer cells into the vascular system. MATERIALS AND METHODS Patients newly diagnosed with suspected invasive bladder cancer and planned for transurethral resection of bladder tumor in 2012 to 2013 were enrolled in the study. Before transurethral bladder tumor resection a vascular surgeon placed a venous catheter in the inferior vena cava via the femoral vein. Blood samples were drawn before and during the resection from the inferior vena cava and a peripheral vein, and analyzed for circulating cancer cells using the CellSearch® system. The number of circulating tumor cells identified was compared in preoperative and intraoperative blood samples. RESULTS The circulating tumor cell data on 16 eligible patients were analyzed. In 6 of 7 positive inferior vena cava samples (86%) the number of circulating tumor cells was increased intraoperatively (28 vs 9, 28 vs 0, 28 vs 5, 3 vs 0, 4 vs 0, 1 vs 0), and results were similar, although less conclusive, for the corresponding peripheral vein samples. CONCLUSIONS Our study confirms that tumor cells can be released into the circulation during transurethral bladder tumor resection. It is currently unknown whether this will increase the risk of metastatic disease.

Increased gene copy number of KIT and VEGFR2 at 4q12 in primary breast cancer is related to an aggressive phenotype and impaired prognosis.

Triple‐negative breast cancer (TNBC) is associated with poor prognosis and no targeted treatments are available for TNBC. Drugs inhibiting tyrosine kinases, such as vascular endothelial growth factor receptor 2 (VEGFR2) and KIT, have shown some promising results for patients with TNBC. The aim of the study was to investigate whether gains and/or amplifications of VEGFR2 and KIT, located at 4q12, occur in TNBC. Fluorescence in situ hybridization (FISH) was used to quantify gene copy numbers of VEGFR2 and KIT in 83 primary human breast cancers including 31 TNBCs. Gains were defined as ≥4 gene copies in >40% of the cancer cells, whereas amplification was defined as CEP >2 in more than 10% of the cancer cells. A tumor was considered FISH positive for KIT and/or VEGFR2 if it displayed copy number gain and/or amplification. Ten (32%) of the TNBCs were VEGFR2 FISH positive and nine (29%) were KIT FISH positive, whereas non‐TNBCs were FISH positive for VEGFR2 and KIT in nine (18%) cases for both genes, but no significant difference between TNBCs and non‐TNBCs was found. FISH positivity for VEGFR2 and KIT was significantly correlated (χ2 test, P < 0.001), and significantly related to ER negativity and high Nottingham histological grade (NHG). A significantly worse 5‐year breast cancer specific survival (BCSS) was seen for FISH positive cases. Increased copy number of VEGFR2 and KIT thus has the potential of functioning as a novel predictive biomarker for selected targeted therapy particularly in the difficult‐to‐treat TNBC patient category.

Adult UrologyOncology: Adrenal/Renal/Upper Tract/BladderTransurethral Bladder Tumor Resection Can Cause Seeding of Cancer Cells into the Bloodstream

PURPOSE Transurethral bladder tumor resection is the initial diagnostic procedure for bladder cancer. Hypothetically tumor resection could induce seeding of cancer cells into the circulation and subsequent metastatic disease. In this study we ascertain whether transurethral bladder tumor resection induces measurable seeding of cancer cells into the vascular system. MATERIALS AND METHODS Patients newly diagnosed with suspected invasive bladder cancer and planned for transurethral resection of bladder tumor in 2012 to 2013 were enrolled in the study. Before transurethral bladder tumor resection a vascular surgeon placed a venous catheter in the inferior vena cava via the femoral vein. Blood samples were drawn before and during the resection from the inferior vena cava and a peripheral vein, and analyzed for circulating cancer cells using the CellSearch® system. The number of circulating tumor cells identified was compared in preoperative and intraoperative blood samples. RESULTS The circulating tumor cell data on 16 eligible patients were analyzed. In 6 of 7 positive inferior vena cava samples (86%) the number of circulating tumor cells was increased intraoperatively (28 vs 9, 28 vs 0, 28 vs 5, 3 vs 0, 4 vs 0, 1 vs 0), and results were similar, although less conclusive, for the corresponding peripheral vein samples. CONCLUSIONS Our study confirms that tumor cells can be released into the circulation during transurethral bladder tumor resection. It is currently unknown whether this will increase the risk of metastatic disease.

The Three Receptor Tyrosine Kinases c-KIT, VEGFR2 and PDGFRα, Closely Spaced at 4q12, Show Increased Protein Expression in Triple-Negative Breast Cancer.

Background Triple-negative breast cancer (TNBC) is a heterogeneous subgroup of breast cancer with poor prognosis and no targeted therapy available. Receptor tyrosine kinases (RTKs) are emerging targets in anticancer therapy and many RTK-inhibiting drugs are currently being developed. The aim of this study was to elucidate if there is a correlation between the protein expression of three RTKs c-KIT, VEGFR2 and PDGFRα, their gene copy number, and prognosis in TNBC compared to non-TNBC. Methods Tumor tissue samples from patients diagnosed with primary breast cancer were stained with immunohistochemistry (IHC) for protein assessment, and with fluorescence in situ hybridization (FISH) for gene copy number determination. Breast cancer mortality (BCM), measured from the date of surgery to death, was used as endpoint. Results The cohort included 464 patients, out of which 34 (7.3%) had a TNBC. High expression of the three RTKs was more common in TNBC compared to non-TNBC: c-KIT 49% vs. 10% (P<0.001), PDGFRα 32% vs. 19% (P = 0.07) and VEGFR2 32% vs. 6% (P<0.001). The odds ratio (OR) of c-KIT, VEGFR2 and PDGFRα positivity, adjusted for tumor characteristics, was 6.8, 3.6 and 1.3 times higher for TNBC than for non-TNBC. 73.5% of the TNBC had high expression of at least one of the three investigated receptors, compared to 30.0% of the non-TNBC (P<0.001). Survival analysis showed no significant difference in BCM for TNBC patients with high vs. low c-KIT, PDGFRα or VEGFR2 protein expression. 193 (42%) tumors were evaluated with FISH. No correlation was seen between increased gene copy number and TNBC, or between increased gene copy number and high protein expression of the RTK. Conclusion c-KIT, VEGFR2 and PDGFRα show higher protein expression in TNBC compared to non-TNBC. Further investigation clarifying the importance of these RTKs in TNBC is encouraged, as they are possible targets for anticancer therapy.

A novel method for downstream characterization of breast cancer circulating tumor cells following CellSearch isolation.

BackgroundEnumeration of circulating tumor cells (CTCs) obtained from minimally invasive blood samples has been well established as a valuable monitoring tool in metastatic and early breast cancer, as well as in several other cancer types. The gold standard technology for detecting CTCs in blood against a backdrop of millions of leukocytes is the FDA-approved CellSearch system (Janssen Diagnostics), which relies on EpCAM-based immunomagnetic separation. Secondary characterization of these cells could enable treatment selection based on specific targets in these cells, as well as providing a real time window into the metastatic process and offering unique insights into tumor heterogeneity. The objective of this study was to develop a method for downstream characterization of CTCs following isolation with the CellSearch system.MethodsAn in vitro CTC model system focusing on clinically useful treatment predictive biomarkers in breast cancer, specifically the estrogen receptor α (ERα) and the human epidermal growth factor receptor 2 (HER2), was established using healthy donor blood spiked with breast cancer cell lines MCF7 (ERα+/HER2−) and SKBr3 (ERα−/HER2+). Following CTC isolation by CellSearch, the captured CTCs were further enriched and fixed on a microscope slide using the in-house-developed CTC-DropMount technique.ResultsThe recovery rate of CTCs after CellSearch Profile analysis and CTC-DropMount was 87%. A selective and consistent triple-immunostaining protocol was optimized. Cells positive for DAPI, cytokeratin (CK) 8, 18 and 19, but negative for the leukocyte-specific marker CD45, were classified as CTCs and subsequently analyzed for ERα and HER2 expression. The method was verified in breast cancer patient samples, thus demonstrating its clinical relevance.ConclusionsOur results show that it is possible to ascertain the status of important predictive biomarkers expressed in breast cancer CTCs using the newly developed CTC-DropMount technique. Downstream characterization of multiple biomarkers using a standard fluorescence microscope demonstrates that important clinical and biological information may be obtained from a single patient blood sample following either CellSearch epithelial or profile analyses.Trial registrationClinical Trials NCT01322893

Circulating tumor cells in patients with advanced urothelial carcinoma of the bladder: Association with tumor stage, lymph node metastases, FDG-PET findings, and survival

BACKGROUND There are currently no methods in clinical use that can detect early systemic dissemination of urothelial tumor cells. OBJECTIVE To evaluate measurement of circulating tumor cells (CTCs) as a biomarker for disseminated disease in patients with advanced bladder cancer. DESIGN, SETTING, AND PARTICIPANTS Between March 2013 and October 2015, 88 patients were prospectively included in the study: 78 were scheduled for radical cystectomy (RC) ± perioperative chemotherapy and 10 treated with palliative chemotherapy. The CellSearch CTC test was further assessed in this context by investigating expression of epithelial cell adhesion molecule (EpCAM) in primary tumors obtained at cystectomy from an independent cohort of 409 patients. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Presence of CTCs was tested for association with tumor stage, lymph node metastases, metastatic disease on [18 F]-fluorodeoxyglucose-positron emission tomography (FDG-PET), and cancer-specific and progression-free survival. RESULTS CTCs were detected in 17/88 patients (19%). In 61 patients who underwent FDG-PET-computed tomography (CT), a statistically significant association with presence of CTCs was found for radiological metastatic disease but not for normal PET-CT results (12/35 [34%] vs. 2/26 [8%], P = 0.014). After a median follow-up time of 16.5 months (95% CI: 9.6-21.4), presence of CTCs was associated with an increased risk of progression among patients treated with RC with or without perioperative chemotherapy (n = 75, P = 0.049). A multivariate analysis adjusted for clinical tumor stage, clinical lymph node status, and age showed that CTCs were an independent marker of progression (n = 75; hazard ratio = 2.78; 95% CI: 1.005-7.69; P = 0.049) but not of cancer-specific death (P = 0.596). In 409 cystectomised patients, more than 392 (96%) of the bladder tumors expressed EpCAM. CONCLUSIONS CTCs were present in 19% of patients with advanced urothelial tumors and were associated with metastatic disease on FDG-PET-CT and with increased risk of disease progression after RC. A significant portion of urothelial cancer cells do express EpCAM and can thus be identified using EpCAM-antigen-based CTC detection methods.