Exploring evolutionary trajectories in ovarian cancer patients by longitudinal analysis of ctDNA

OBJECTIVES

We analysed whether temporal heterogeneity of ctDNA encodes evolutionary patterns in ovarian cancer.

METHODS

Targeted sequencing of 275 cancer-associated genes was performed in a primary tumor biopsy and in ctDNA of six longitudinal plasma samples from 15 patients, using the Illumina platform.

RESULTS

While there was low overall concordance between the mutational spectrum of the primary tumor biopsies vs. ctDNA, TP53 variants were the most commonly shared somatic alterations. Up to three variant clusters were detected in each tumor biopsy, likely representing predominant clones of the primary tumor, most of them harbouring a TP53 variant. By tracing these clusters in ctDNA, we propose that liquid biopsy may allow to assess the contribution of ancestral clones of the tumor to relapsed abdominal masses, revealing two evolutionary patterns. In pattern#1, clusters detected in the primary tumor biopsy were likely relapse seeding clones, as they contributed a major share to ctDNA at relapse. In pattern#2, similar clusters were present in tumors and ctDNA; however, they were entirely cleared from liquid biopsy after chemotherapy and were undetectable at relapse. ctDNA private variants were present among both patterns, with some of them mirroring subclonal expansions after chemotherapy.

CONCLUSIONS

We demonstrate that tracing the temporal heterogeneity of ctDNA, even below exome scale resolution, deciphers evolutionary trajectories in ovarian cancer. Furthermore, we describe two evolutionary patterns that may help to identify relapse seeding clones for targeted therapy.

A predictive and prognostic model for surgical outcome and prognosis in ovarian cancer computed by clinico-pathological and serological parameters (CA125, HE4, mesothelin)

OBJECTIVES

Numerous prognostic models have been proposed for ovarian cancer, extending from single serological factors to complex gene-expression signatures. Nonetheless, these models have not been routinely translated into clinical practice. We constructed a robust and readily calculable model for predicting surgical outcome and prognosis of ovarian cancer patients by exploiting commonly available clinico-pathological factors and three selected serum parameters.

METHODS

Serum CA125, human epididymis protein 4 (HE4) and mesothelin (MSL) were quantified by Lumipulse® G chemiluminescent enzyme immunoassay (Fujirebio) in a total of 342 serum samples from 190 ovarian cancer patients, including 152 paired pre- and post-operative samples.

RESULTS

Detection of pre-operative HE4 and CA125 was the optimal marker combination for blood-based prediction of surgical outcome (AUC=0.86). We constructed a prognostic model, computed by serum levels of pre-operative CA125, post-operative HE4, post-operative MSL and surgical outcome. Prognostic performance of our model was superior to any of these parameters alone and was independent from BRCA1/2 mutational status. We subsequently transformed our model into a prognostic risk index, stratifying patients as "lower risk" or "higher risk". In "higher risk" patients, relapse or death was predicted with an AUC of 0.89 and they had a significantly shorter progression free survival (HR: 9.74; 95 % CI: 5.95-15.93; p<0.0001) and overall survival (HR: 5.62; 95 % CI: 3.16-9.99; p<0.0001) compared to "lower risk" patients.

CONCLUSIONS

We present a robust predictive/prognostic model for ovarian cancer, which could readily be implemented into routine diagnostics in order to identify ovarian cancer patients at high risk of recurrence.

RANK Expression as an Independent Predictor for Response to Neoadjuvant Chemotherapy in Luminal-Like Breast Cancer: A Translational Insight from the GeparX Trial

PURPOSE

The GeparX study investigated whether denosumab as add-on treatment to nab-paclitaxel-based neoadjuvant chemotherapy (NACT) with two different schedules (125 mg/m² weekly vs. day 1, 8 every 22 days) may increase pathologic complete response (pCR) rate. The addition of denosumab to NACT did not improve pCR rates as recently published. In this study, we investigated whether receptor activator of nuclear factor-kappa B (RANK) expression, as part of the denosumab target pathway: (i) may retrospectively identify a subgroup of patients with additional clinical benefit of denosumab or (ii) may predict response to nab-paclitaxel NACT.

EXPERIMENTAL DESIGN

RANK protein was IHC-stained on pre-therapeutic core biopsies from patients of the GeparX study (n = 667) with the antibody RANK/Envision System HRP (DAB) and was analyzed for the percentage of membranous RANK tumor cell staining (>5% RANKhigh vs. ≤5% RANKlow).

RESULTS

We could not identify any patient subgroup with differential response under denosumab add-on treatment in patients with RANKhigh expression [139/667, 20.8%; OR, 0.86; 95% confidence interval (CI), 0.44-1.68; P = 0.667] or RANKlow expression (528/667 (79.2%) OR, 1.10; 95% CI, 0.78-1.56; P = 0.589; Pinteraction = 0.528). However, the pCR rate was higher in the RANKhigh subgroup compared with RANKlow (50% vs. 39%; OR, 1.52; 95% CI, 1.04-2.21; P = 0.037). RANK expression constituted an independent predictor of response to NACT frequently in patients with luminal-like subtype (HR+/HER2-; OR, 2.98; 95% CI, 1.30-6.79; P = 0.010). No predictive value of RANK expression among the different nab-paclitaxel regimens was observed.

CONCLUSION

We report RANK expression to be an independent predictive biomarker for response to NACT in patients with luminal-like breast cancer.

Correction: Diagnostic Benefit of the Detection of Mitotic Figures in Endometriotic Lesions

[This corrects the article DOI: 10.1055/a-1580-0601.].

Establishment and Molecular Characterization of an In Vitro Model for PARPi-Resistant Ovarian Cancer

Overcoming PARPi resistance is a high clinical priority. We established and characterized comparative in vitro models of acquired PARPi resistance, derived from either a BRCA1-proficient or BRCA1-deficient isogenic background by long-term exposure to olaparib. While parental cell lines already exhibited a certain level of intrinsic activity of multidrug resistance (MDR) proteins, resulting PARPi-resistant cells from both models further converted toward MDR. In both models, the PARPi-resistant phenotype was shaped by (i) cross-resistance to other PARPis (ii) impaired susceptibility toward the formation of DNA-platinum adducts upon exposure to cisplatin, which could be reverted by the drug efflux inhibitors verapamil or diphenhydramine, and (iii) reduced PARP-trapping activity. However, the signature and activity of ABC-transporter expression and the cross-resistance spectra to other chemotherapeutic drugs considerably diverged between the BRCA1-proficient vs. BRCA1-deficient models. Using dual-fluorescence co-culture experiments, we observed that PARPi-resistant cells had a competitive disadvantage over PARPi-sensitive cells in a drug-free medium. However, they rapidly gained clonal dominance under olaparib selection pressure, which could be mitigated by the MRP1 inhibitor MK-751. Conclusively, we present a well-characterized in vitro model, which could be instrumental in dissecting mechanisms of PARPi resistance from HR-proficient vs. HR-deficient background and in studying clonal dynamics of PARPi-resistant cells in response to experimental drugs, such as novel olaparib-sensitizers.

Palbociclib impairs the proliferative capacity of activated T cells while retaining their cytotoxic efficacy

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor palbociclib is an emerging cancer therapeutic that just recently gained Food and Drug Administration approval for treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor (Her)2-negative breast cancer in combination with the ER degrader fulvestrant. However, CDK4/6 inhibitors are not cancer-specific and may affect also other proliferating cells. Given the importance of T cells in antitumor defense, we studied the influence of palbociclib/fulvestrant on human CD3+ T cells and novel emerging T cell-based cancer immunotherapies. Palbociclib considerably inhibited the proliferation of activated T cells by mediating G0/G1 cell cycle arrest. However, after stopping the drug supply this suppression was fully reversible. In light of combination approaches, we further investigated the effect of palbociclib/fulvestrant on T cell-based immunotherapies by using a CD3-PSCA bispecific antibody or universal chimeric antigen receptor (UniCAR) T cells. Thereby, we observed that palbociclib clearly impaired T cell expansion. This effect resulted in a lower total concentration of interferon-γ and tumor necrosis factor, while palbociclib did not inhibit the average cytokine release per cell. In addition, the cytotoxic potential of the redirected T cells was unaffected by palbociclib and fulvestrant. Overall, these novel findings may have implications for the design of treatment modalities combining CDK4/6 inhibition and T cell-based cancer immunotherapeutic strategies.

The effect of denosumab on disseminated tumor cells (DTCs) of breast cancer patients with neoadjuvant treatment: a GeparX translational substudy

Background

Disseminated tumor cells (DTCs) in the bone marrow are observed in about 40% at primary diagnosis of breast cancer and predict poor survival. While anti-resorptive therapy with bisphosphonates was shown to eradicate minimal residue disease in the bone marrow, the effect of denosumab on DTCs, particularly in the neoadjuvant setting, is largely unknown. The recent GeparX clinical trial reported that denosumab, applied as an add-on treatment to nab-paclitaxel based neoadjuvant chemotherapy (NACT), did not improve the patient’s pathologic complete response (pCR) rate. Herein, we analyzed the predictive value of DTCs for the response to NACT and interrogated whether neoadjuvant denosumab treatment may eradicate DTCs in the bone marrow.

Methods

A total of 167 patients from the GeparX trial were analyzed for DTCs at baseline by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. Initially DTC-positive patients were re-analyzed for DTCs after NACT ± denosumab.

Results

At baseline, DTCs were observed in 43/167 patients (25.7%) in the total cohort, however their presence did not predict response to nab-paclitaxel based NACT (pCR rates: 37.1% in DTC-negative vs. 32.6% DTC-positive; p = 0.713). Regarding breast cancer subtypes, the presence of DTCs at baseline was numerically associated with response to NACT in TNBC patients (pCR rates: 40.0% in DTC-positive vs. 66.7% in DTC-negative patients; p = 0.16). Overall, denosumab treatment did not significantly increase the given DTC-eradication rate of NACT (NACT: 69.6% DTC-eradication vs. NACT + denosumab: 77.8% DTC-eradication; p = 0.726). In TNBC patients with pCR, a numerical but statistically non-significant increase of DTC-eradication after NACT + denosumab was observed (NACT: 75% DTC-eradication vs. NACT + denosumab: 100% DTC-eradication; p = 1.00).

Conclusion

This is the first study worldwide, demonstrating that neoadjuvant add-on denosumab over a short-term period of 24 months does not increase the DTC-eradication rate in breast cancer patients treated with NACT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-023-01619-2.

Bevacizumab May Differentially Improve Prognosis of Advanced Ovarian Cancer Patients with Low Expression of VEGF-A165b, an Antiangiogenic VEGF-A Splice Variant

PURPOSE

The identification of a robust IHC marker to predict the response to antiangiogenic bevacizumab in ovarian cancer is of high clinical interest. VEGF-A, the molecular target of bevacizumab, is expressed as multiple isoforms with pro- or antiangiogenic properties, of which VEGF-A165b is the most dominant antiangiogenic isoform. The balance of VEGF-A isoforms is closely related to the angiogenic capacity of a tumor and may define its vulnerability to antiangiogenic therapy. We investigated whether the expression of VEGF-A165b could be related to the effect of bevacizumab in advanced ovarian cancer patients.

EXPERIMENTAL DESIGN

Formalin-fixed paraffin-embedded tissues from 413 patients of the ICON7 multicenter phase III trial, treated with standard platinum-based chemotherapy with or without bevacizumab, were probed for VEGF-A165b expression by IHC.

RESULTS

In patients with low VEGF-A165b expression, the addition of bevacizumab to standard platinum-based chemotherapy significantly improved progression-free (HR: 0.727; 95% CI, 0.538-0.984; P = 0.039) and overall survival (HR: 0.662; 95% CI, 0.458-0.958; P = 0.029). Multivariate analysis showed that the addition of bevacizumab in low VEGF-A165b-expressing patients conferred significant improvements in progression-free survival (HR: 0.610; 95% CI, 0.446-0.834; P = 0.002) and overall survival (HR: 0.527; 95% CI, 0.359-0.775; P = 0.001), independently from established risk factors.

CONCLUSIONS

We demonstrate for the first time that bevacizumab may differentially improve the prognosis of advanced ovarian cancer patients with low expression of VEGF-A165b, an antiangiogenic VEGF-A splice variant. We envision that this novel biomarker could be implemented into routine diagnostics and may have direct clinical implications for guiding bevacizumab-related treatment decisions in advanced ovarian cancer patients.

Clinical impact of soluble Neuropilin-1 in ovarian cancer patients and its association with its circulating ligands of the HGF/c-MET axis

BACKGROUND

Neuropilin (NRP) is a transmembrane protein, which has been shown to be a pro-angiogenic mediator and implicated as a potential driver of cancer progression. NRP-1 up-regulation in ovarian cancer tissue predicts poor prognosis. However, the clinical relevance of the soluble form of NRP-1 (sNRP-1) as a circulating biomarker in ovarian cancer patients is unknown.

METHODS/PATIENTS COHORT

sNRP-1 levels were quantified in a cohort of 88 clinically documented ovarian cancer patients by a commercially available sNRP-1 enzyme-linked immunosorbent assay (ELISA) kit (Biomedica, Vienna, Austria). Patients (81.8% with FIGOIII/IV) received primary cytoreductive surgery with the aim of macroscopic complete resection (achieved in 55.7% of patients) and the recommendation of adjuvant chemotherapy in line with national guidelines.

RESULTS

Higher levels of sNRP-1 reflected more advanced disease (FIGO III/IV) and indicated a trend towards suboptimal surgical outcome, i.e. any residual tumor. sNRP-1 was neither related to the patients' age nor the BRCA1/2 mutational status. Patients with higher sNRP-1 levels at primary diagnosis had a significantly reduced progression-free survival (PFS) (HR = 0.541, 95%CI: 0.304 - 0.963; p = 0.037) and overall survival (OS) (HR = 0.459, 95%CI: 0.225 - 0.936; p = 0.032). Principal component analysis showed that sNRP-1 levels were unrelated to the circulating hepatocyte growth factor (HGF) and the soluble ectodomain of its receptor the tyrosine kinase mesenchymal-epithelial transition (c-MET), suggesting that there is no proportional serological concentration gradient of soluble components of the NRP-1/HGF/c-MET signaling axis.

CONCLUSIONS

In line with the previously shown tissue-based prognostic role, we demonstrated for the first time that sNRP-1 can also act as a readily accessible, prognostic biomarker in the circulation of patients with ovarian cancer at primary diagnosis. Given its known role in angiogenesis and conferring resistance to the poly ADP-ribose polymerase (PARP) inhibitor olaparib in vitro, our results encourage more detailed investigation into sNRP-1 as a potential predictive biomarker for bevacizumab and/or PARP-inhibitor treatment.

Defining a prognostic risk score in ovarian cancer patients by integrated analysis of serum mesothelin, HE4, CA125 and surgical outcome

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Background: In ovarian cancer, serum CA125 is currently the only biomarker used in routine clinical practice and has several limitations, e.g. it is not entirely specific for ovarian malignancy. Alternative serum biomarkers have been proposed for ovarian cancer, such as mesothelin or human epididymis protein 4 (HE4). Although it is known that single marker analysis is often insufficient for diagnostic purposes or relapse prediction, no comprehensive studies on the combination of these markers have been conducted, yet. Using a multi-marker prediction model, we herein investigated the clinical usefulness of mesothelin and HE4, detected in a sequence of pre- and post-operative serum samples, in complementing the standard marker CA125. Methods: Serum mesothelin, HE4 and CA125 were quantified by Lumipulse G chemiluminescent enzyme immunoassay (Fujirebio) in a total of 432 serum samples from 90 healthy controls and 192 ovarian cancer patients (thereof 81.8% with FIGO III/IV), including 151 paired pre- and post-operative samples. Results: Pre-operative serum mesothelin and HE4 were significantly elevated compared to healthy controls with a median ratio (IQR) to controls of 2.6 and 9.6, respectively (p < 0.0001). High pre-operative levels of mesothelin or HE4 alone were significantly correlated with advanced FIGO-stage (p < 0.0001) and predicted surgical outcome (p < 0.0001). We retrospectively compiled mesothelin and HE4 levels with CA125, BRCA mutational status and surgical outcome, in order to define a multi-marker setting. Both, mesothelin and HE4 levels were independent from BRCA mutational status, however they positively correlated with CA125. Detection of pre-operative HE4 > 498pM (OR = 4.1, p < 0.0001) combined with pre-operative CA125 > 516U/mL (OR = 2.2, p = 0.001) was the best combination to predict surgical outcome (AUC = 0.815). Finally, we defined a prognostic signature, including pre-operative CA125, post-operative mesothelin, HE4 and surgical outcome, which was superior to the individual prognostic capacity of all included parameters. Our model allowed the calculation of a weighted risk score, stratifying patient at “lower risk” (score 0-4) or at “higher risk” (score 5-10). Patients with higher risk had significantly shorter PFS (19.0 months (95%CI = 16.1-21.8) vs 64.1 months (95%CI = 56.8-71.3) p < 0.0001) and OS (34.0 months (95%CI = 28.6-39.3) vs 71.2 months (95%CI = 64.6-77.7) p < 0.0001). Conclusions: This is the first study, proposing an integrated prognostic risk score for ovarian cancer patients, which could easily be implemented into routine diagnostics and may guide personalized treatment decisions. Patients at “higher risk”, as identified by this model, could potentially benefit from an intensified therapy regime, whereas patients at “lower risk” might be suitable for treatment de-escalation.

Evaluation of circulating Dickkopf-1 as a prognostic biomarker in ovarian cancer patients

OBJECTIVES

Dickkopf-1 (DKK1) is a secreted protein, known for suppressing the differentiation and activity of bone-building osteoblasts by acting as an inhibitor of Wnt-signalling. Soluble DKK1 (sDKK1) has been proposed as prognostic biomarker for a wide range of malignancies, however, clinical relevance of sDKK1 as potential blood-based marker for ovarian cancer is unknown.

METHODS

sDKK1 levels were quantified in a cohort of 150 clinically documented ovarian cancer patients by a commercially available DKK1 ELISA (Biomedica, Vienna, Austria).

RESULTS

Median sDKK1 level was significantly elevated at primary diagnosis of ovarian cancer compared to healthy controls (estimated difference (ED) of 7.75 ng/mL (95% CI: 3.01-12.30 ng/mL, p=0.001)). Higher levels of sDKK1 at diagnosis indicated an increased volume of intraoperative malignant ascites (ED 7.08 pmol/L, 95% CI: 1.46-13.05, p=0.02) and predicted suboptimal debulking surgery (ED 6.88 pmol/L, 95% CI: 1.73-11.87, p=0.01). sDKK1 did not correlate with CA125 and higher sDKK1 levels predicted a higher risk of recurrence and poor survival (PFS: HR=0.507, 95% CI: 0.317-0.809; p=0.004; OS: HR=0.561, 95% CI: 0.320-0.986; p=0.044). Prognostic relevance of sDKK1 was partly sustained in wtBRCA patients (PFS: HR=0.507, 95% CI: 0.317-0.809; p=0.004).

CONCLUSIONS

This is the first study demonstrating the prognostic relevance of sDKK1 in ovarian cancer patients, including those with wtBRCA 1/2 status. Our data encourage further evaluation of sDKK1 in ovarian cancer patients, possibly in terms of a therapy monitoring marker or a response predictor for sDKK1-directed targeted therapies.

FNTB Promoter Polymorphisms Are Independent Predictors of Survival in Patients with Triple Negative Breast Cancer

In breast cancer, the promising efficacy of farnesyltransferase inhibitors (FTIs) in preclinical studies is in contrast to only limited effects in clinical Phase II–III trials. The objective of this study was to explore the clinical relevance of farnesyltransferase β-subunit (FNTB) single nucleotide promoter polymorphisms (FNTB-173 6G > 5G (rs3215788), -609 G > C (rs11623866) and -179 T > A (rs192403314)) in early breast cancer. FNTB genotyping was performed by pyrosequencing in 797 patients from a prospective multicentre observational PiA trial (NCT 01592825). In the total cohort, the FNTB-173 6G > 5G polymorphism was an independent predictor of RFI (HR = 0.568; 95% CI = 0.339–0.949, p = 0.031), OS (HR = 0.629; 95% CI = 0.403–0.980, p = 0.040) and BCSS (HR = 0.433; 95% CI = 0.213–0.882; p = 0.021), whereas the FNTB-609 G > C polymorphism was an independent predictor of RFI (HR = 0.453; 95% CI = 0.226–0.910, p = 0.026) and BCSS (HR = 0.227; 95% CI = 0.075–0.687, p = 0.009). Subtype analysis revealed the independent prognostic relevance of FNTB promoter polymorphisms, particularly in TNBC but not in luminal or HER2-positive intrinsic subtypes. Finally, we used electrophoretic mobility shift assays (EMSAs) to confirm in vitro that the polymorphism FNTB-173 6G > 5G resulted in the differential binding of nuclear proteins from five different breast cancer cell lines. This is the first study on breast cancer suggesting that FNTB promoter polymorphisms (i) are independent prognostic biomarkers, particularly in patients with early TNBC, and (ii) could modulate FNTB’s transcriptional activity.

Diagnostic Benefit of the Detection of Mitotic Figures in Endometriotic Lesions

Objectives Endometriosis is a chronic disease which is diagnosed by surgical intervention combined with a histological work-up. Current international and national recommendations do not require the histological determination of the proliferation rate. The diagnostic and clinical importance of the mitotic rate in endometriotic lesions still remains to be elucidated. Methods In this retrospective study, the mitotic rates and clinical data of 542 patients with histologically diagnosed endometriosis were analyzed. The mean patient age was 33.5 ± 8.0 (17 - 72) years, and the mean reproductive lifespan was 21.2 ± 7.8 (4 - 41) years. Patients were divided into two groups and patients' reproductive history and clinical endometriosis characteristics were compared between groups. The study group consisted of women with confirmed mitotic figures (n = 140, 25.83%) and the control group comprised women without proliferative activity according to their mitotic rates (n = 402, 74.27%). Results Women with endometriotic lesions and histologically confirmed mitotic figures were significantly more likely to have a higher endometriosis stage (p = 0.001), deep infiltrating endometriosis (p < 0.001), ovarian endometrioma (p = 0.012), and infertility (p = 0.049). A mitotic rate > 0 was seen significantly less often in cases with incidental findings of endometriosis (p = 0.031). The presence of symptoms and basic characteristics such as age, age at onset of menarche, reproductive lifespan and parity did not differ between the group with and the group without mitotic figures. Conclusion This study shows that a simple histological assessment of the mitotic rate offers additional diagnostic value for the detection of advanced stages of endometriosis. The possible role as a predictive marker for the recurrence of endometriosis or the development of endometriosis-associated cancer will require future study.

Reorganization of the osteocyte lacuno-canalicular network characteristics in tumor sites of an immunocompetent murine model of osteotropic cancers

Mechanosensitive osteocytes are central regulators of bone resorption and formation. However, during the formation of bone metastases, which arise as consequences of breast and prostate cancer and skew homeostatic bone remodeling to favor osteolytic, osteosclerotic or mixed lesions, only a paucity of data exists on tumor-associated osteocyte interaction. Herein, we used a suite of high-resolution imaging and histological techniques to evaluate the effect of osteotropic cancer on cortical bone microarchitecture. Confocal imaging highlighted a direct contact between tumor cells residing in the bone marrow and osteocytes. High-resolution microcomputed tomography revealed a 10-12% larger osteocyte lacuna volume in the presence of tumor cells at day 21 after intratibial injection of EO771-Luc breast and RM1-Luc prostate cancer cells. The 3D representative of the spatial distribution of cortical bone microporosity showed i) a regional accumulation of vascular canals and large lacunae with low connectivity in osteosclerotic regions of interest and ii) an absence of vascular canals and large lacunae in osteolytic regions. These findings pinpoint the relationship between the presence of tumor cells in the bone marrow microenvironment and osteocyte lacunar characteristics and cortical bone blood vessel structure.

Diminished PLK2 Induces Cardiac Fibrosis and Promotes Atrial Fibrillation

[Figure: see text].

The levels of soluble cMET ectodomain in the blood of patients with ovarian cancer are an independent prognostic biomarker

The tyrosine kinase mesenchymal–epithelial transition (cMET) is typically overexpressed in up to 75% of patients with ovarian cancer, and cMET overexpression has been associated with poor prognosis. The proteolytic release of the soluble cMET (sMET) ectodomain by metalloproteases, a process called ectodomain shedding, reflects the malignant potential of tumour cells. sMET can be detected in the human circulation and has been proposed as biomarker in several cancers. However, the clinical relevance of sMET in ovarian cancer as blood‐based biomarker is unknown and was therefore investigated in this study. sMET levels were determined by enzyme‐linked immunosorbent assay in a set of 432 serum samples from 85 healthy controls and 86 patients with ovarian cancer (87% FIGO III/IV). Samples were collected at primary diagnosis, at four longitudinal follow‐up time points during the course of treatment and at disease recurrence. Although there was no significant difference between median sMET levels at primary diagnosis of ovarian cancer vs. healthy controls, increased sMET levels at primary diagnosis were an independent predictor of shorter PFS (HR = 0.354, 95% CI: 0.130–0.968, P = 0.043) and shorter OS (HR = 0.217, 95% CI: 0.064–0.734, P = 0.014). In the follow‐up samples, sMET levels were prognostically most informative after the first three cycles of chemotherapy, with high sMET levels being an independent predictor of shorter PFS (HR = 0.245, 95% CI: 0.100–0.602, P = 0.002). This is the first study to suggest that sMET levels in the blood can be used as an independent prognostic biomarker for ovarian cancer. Patients at high risk of recurrence and with poor prognosis, as identified based on sMET levels in the blood, could potentially benefit from cMET‐directed therapies or other targeted regimes, such as PARP inhibitors or immunotherapy.

Prognostic relevance of longitudinal HGF levels in serum of patients with ovarian cancer

The pleiotropic protein hepatocyte growth factor (HGF) is the only known ligand of the tyrosine kinase mesenchymal–epithelial transition (cMET) receptor. The HGF/cMET pathway mediates invasion and migration of ovarian cancer cells, and upregulation of HGF/cMET pathway components has been associated with poor prognosis. This study investigated the clinical relevance of circulating HGF in serum of patients with ovarian cancer. Serum HGF (sHGF) was determined by enzyme‐linked immunosorbent assay in a total of 471 serum samples from 82 healthy controls and 113 patients with ovarian cancer (88.5% with ≥ FIGO III). Patient samples were collected at primary diagnosis and at four follow‐up time points throughout treatment and at disease recurrence. Patients with ovarian cancer showed elevated median sHGF levels at primary diagnosis, and sHGF levels transiently increased after surgery and normalized in the course of chemotherapy, even dropping below initial baseline. Higher levels of sHGF were an independent predictor for shorter overall survival (OS) (a) at primary diagnosis (HR = 0.41, 95% CI: 0.22–0.78, P = 0.006), (b) at longitudinal follow‐up time points (after surgery and before/during/after chemotherapy), (c) along the patients’ individual dynamics (HR = 0.21, 95% CI: 0.07–0.63, P = 0.005), and (d) among a subgroup analysis of patients with BRCA1/2 wild‐type ovarian cancer. This is the first study proposing sHGF as an independent prognostic biomarker for ovarian cancer at primary diagnosis and in the course of platinum‐based chemotherapy, irrespective of the postoperative residual disease after surgical debulking. sHGF could be implemented into clinical diagnostics as a CA125 auxiliary tumor marker for individualized prognosis stratification and sHGF‐guided therapy monitoring.

The effect of the triazene compound CT913 on ovarian cancer cells in vitro and its synergistic interaction with the PARP-inhibitor olaparib

OBJECTIVES

Extending the therapeutic spectrum of PARP-inhibitors (PARPi) beyond BRCA1-deficiency and/or overcoming PARPi-resistance is of high clinical interest. This is particularly true for the identification of innovative therapeutic strategies for ovarian cancer, given the recent advances in the use of PARPi in clinical practice. In this regard, the combination of PARPi with chemotherapy is a possible strategy for defining new therapeutic standards. In this study, we analyzed the therapeutic effect of novel triazene derivatives, including the drug CT913 and its metabolite CT913-M1 on ovarian cancer cells and describe their interaction with the PARPi olaparib.

METHODS

In vitro assays for drug characterization including RNA-Seq were applied in a selected panel of ovarian cancer cell lines.

RESULTS

CT913 treatment conferred a dose-dependent reduction of cell viability in a set of platinum-sensitive and platinum-resistant ovarian cancer cell lines with an IC₅₀ in the higher micromolar range (553-1083 μM), whereas its metabolite CT913-M1 was up to 69-fold more potent, especially among long-term treatment (IC₅₀ range: 8-138 μM). Neither of the drugs sensitized for cisplatin. CT913 conferred synthetic lethality in BRCA1-deficient ovarian cancer cells, indicating that its effect is augmented by a deficiency in homologous recombination repair (HR). Furthermore, CT913 showed a synergistic interaction with olaparib, independently of BRCA1 mutational status. CT913 strongly induced CDKN1A transcription, suggesting cell cycle arrest as an early response to this drug. It moreover downregulated a variety of transcripts involved in DNA-repair pathways.

CONCLUSIONS

This is the first study, suggesting the novel triazene drug CT913 as enhancer drug for extending the therapeutic spectrum of PARPi.

Anti-tumor effects of mevalonate pathway inhibition in ovarian cancer

BACKGROUND

Ovarian cancer remains the most fatal gynecological malignancy. Current therapeutic options are limited due to late diagnosis in the majority of the cases, metastatic spread to the peritoneal cavity and the onset of chemo-resistance. Thus, novel therapeutic approaches are required. Statins and amino-bisphosphonates are inhibitors of the mevalonate pathway, which is a fundamental pathway of cellular metabolism, essential for cholesterol production and posttranslational protein farnesylation and geranylgeranylation. While this pathway has emerged as a promising treatment target in several human malignancies, its potential as a therapeutic approach in ovarian cancer is still not fully understood.

METHODS

Human ovarian cancer cell lines (IGROV-1, A2780, A2780cis) were treated with increasing concentrations (0.5-100 μM) of statins (simvastatin, atorvastatin, rosuvastatin) and zoledronic acid. Effects on cell vitality and apoptosis were assessed using Cell Titer Blue®, Caspase 3/7 Glo®, clonogenic assays as well as cleaved poly (ADP-ribose) polymerase (cPARP) detection. The inhibition of the mevalonate pathway was confirmed using Western Blot of unprenylated Ras and Rap1a proteins. Quantitative real-time PCR and ELISA were used to analyze modulations on several key regulators of ovarian cancer tumorigenesis.

RESULTS

The treatment of IGROV-1 and A2780 cells with statins and zoledronic acid reduced vitality (by up to 80%; p < 0.001) and induced apoptosis by up to 8-folds (p < 0.001) in a dose-dependent fashion. Rescue experiments using farnesyl pyrophosphate or geranylgeranyl pyrophosphate evidenced that blocked geranylgeranylation is the major underlying mechanism of the pro-apoptotic effects. Gene expression of the tumor-promoting cytokines and mediators, such as transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), interleukin (IL)-8, and IL-6 were significantly suppressed by statins and zoledronic acid by up to 90% (p < 0.001). For all readouts, simvastatin was most potent of all agents used. Cisplatin-resistant A2780cis cells showed a relative resistance to statins and zoledronic acid. However, similar to the effects in A2780 cells, simvastatin and zoledronic acid significantly induced caspase 3/7 activation (6-folds; p < 0.001).

CONCLUSION

Our in vitro findings point to promising anti-tumor effects of statins and zoledronic acid in ovarian cancer and warrant additional validation in preclinical and clinical settings.

Influence of denosumab on disseminated tumor cells (DTC) in the bone marrow of breast cancer (BC) patients with neoadjuvant treatment: A GeparX translational substudy

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Background: DTCs in the bone marrow are observed in up to 30% at primary diagnosis of BC and their presence is an independent prognostic factor for reduced survival. It was shown that antiresorptive therapy eradicates DTCs and improves prognosis in DTC-positive BC patients (pts). In the GeparX phase III prospective randomized trial, denosumab (a monoclonal IgG2-anti-RANKL-antibody) was investigated as add-on treatment to neoadjuvant chemotherapy (NACT) with two different nab-paclitaxel schedules in early high-risk primary BC. In a translational substudy, we analyzed for the first time the influence of short-term denosumab treatment (24 weeks) on the presence of DTCs. Methods: A total of 167 pts from the GeparX trial were analyzed for DTCs at baseline by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. Initially DTC-positive pts were re-analyzed for DTCs after NACT±Denosumab. Results: Overall, 60/167 pts (35.9%) treated with NACT±Denosumab had a pathological complete response (pCR; 55.4% in TNBC, 43.3% in HER2+, 15.3% in HR+/HER2-). At baseline, 43/167 pts (25.7%) were DTC-positive and 41 of those were available for re-analysis of DTCs after NACT±Denosumab. DTC eradication was observed in 77.8% after NACT+Denosumab and in 69.6% after NACT alone (p = 0.726). Due to the limited number of pts eligible for DTC-re-analysis after NACT, a subtype specific analysis for the effect of denosumab was not possible. There was no significant association between pCR and i) the presence of DTCs at baseline (37.1% DTC-negative vs 32.6% positive, p = 0.71) or ii) the eradication of DTCs after NACT±Denosumab (36.7% vs 27.3%, p = 0.72). Notably, in TNBC, we observed a tendency that DTC-positivity at baseline or DTC-persistence after NACT could be associated with reduced pCR rate (40.0% in DTC-positive vs. 66.7% in DTC-negative pts, p = 0.16; 25% in DTC-persistent pts vs. 50% in DTC-eradicated pts, p = 0.59). Conclusions: Denosumab in addition to NACT does not improve pCR, but the suspected effect of denosumab on DTC eradication should be further analyzed in TNBC. Key words: GeparX trial, denosumab, disseminated tumor cells, bone marrow, neoadjuvant chemotherapy. Funding: GeparX and DTC substudy were financially supported by Amgen and Celgene. Clinical trial information: NCT02682693 .

Diphenhydramine increases the therapeutic window for platinum drugs by simultaneously sensitizing tumor cells and protecting normal cells

Platinum-based compounds remain a well-established chemotherapy for cancer treatment despite their adverse effects which substantially restrict the therapeutic windows of the drugs. Both the cell type-specific toxicity and the clinical responsiveness of tumors have been associated with mechanisms that alter drug entry and export. We sought to identify pharmacological agents that promote cisplatin (CP) efficacy by augmenting the levels of drug-induced DNA lesions in malignant cells and simultaneously protecting normal tissues from accumulating such damage and from functional loss. Formation and persistence of platination products in the DNA of individual nuclei were measured in drug-exposed cell lines, in primary human tumor cells and in tissue sections using an immunocytochemical method. Using a mouse model of CP-induced toxicity, the antihistaminic drug diphenhydramine (DIPH) and two methylated derivatives decreased DNA platination in normal tissues and also ameliorated nephrotoxicity, ototoxicity, and neurotoxicity. In addition, DIPH sensitized multiple cancer cell types, particularly ovarian cancer cells, to CP by increasing intracellular uptake, DNA platination, and/or apoptosis in cell lines and in patient-derived primary tumor cells. Mechanistically, DIPH diminished transport capacity of CP efflux pumps MRP2, MRP3, and MRP5 particularly in its C2+C6 bimethylated form. Overall, we demonstrate that DIPH reduces side effects of platinum-based chemotherapy and simultaneously inhibits key mechanisms of platinum resistance. We propose that measuring DNA platination after ex vivo exposure may predict the responsiveness of individual tumors to DIPH-like modulators.

Serum calretinin as an independent predictor for platinum resistance and prognosis in ovarian cancer

Calretinin (CRT) is a calcium-binding protein that controls intracellular calcium signaling. Besides its prominent expression in neurons, serum CRT (sCRT) has recently been suggested as blood-based biomarker for prediagnostic mesothelioma detection. CRT is expressed in ovarian cancer tissues in up to 40% of cases; however, its clinical relevance as blood-based biomarker for ovarian cancer is unknown. sCRT was determined by calretinin enzyme-linked immunoabsorbent assay (Calretinin-ELISA, DLD Diagnostika GmbH, Hamburg, Germany) in a total of 515 serum samples from 116 healthy controls and 134 ovarian cancer patients (thereof 86% with Fédération Internationale de Gynécologie et d'Obstétrique [FIGO] III/IV), including samples at primary diagnosis and at four longitudinal follow-up time points in the course of treatment and at recurrence. sCRT level was significantly increased in ovarian cancer patients compared to healthy controls (estimated difference = 0.3 ng/ml, p < 0.001), was mostly independent from CA125 (r ≤ 0.388) and enabled accurate discrimination between cases and controls (area under the curve = 0.85). Higher sCRT level at primary diagnosis predicted suboptimal debulking (p < 0.001) and was associated with advanced FIGO-stage (p < 0.001) and increased amount of ascites (p < 0.001). sCRT levels at primary diagnosis and its dynamics in the course of chemotherapy were independent predictors for poor progression-free survival (hazard ratio [HR] = 1.99, confidence interval [CI] = [1.13-3.52], p = 0.0181) and overall survival (HR = 15.4, CI = [1.92-124], p = 0.0099). Furthermore, sCRT at primary diagnosis or a relative sCRT increase in the time interval between surgery and the onset of chemotherapy were both independent predictors of platinum resistance (OR = 4.99, CI = [3.50-16,001], p = 0.0016; OR = 2.41, CI = [1.37-6,026], p = 0.0271, respectively). This is the first study that suggests sCRT as liquid biopsy marker for independent prediction of platinum resistance and prognosis.

Serum calretinin as a predictor for recurrence and overall survival in ovarian cancer

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Background: Calretinin (CRT) is a calcium-binding protein, controlling intracellular calcium signaling. Besides its prominent expression in neurons, CRT has diagnostic implications in cancer, particularly in mesothelioma. In a recent liquid biopsy approach, plasma CRT level has been suggested for pre-diagnostic detection of mesothelioma. CRT is also expressed in serous ovarian cancer in about 23% of cases; however, clinical relevance of serum CRT is completely unknown and shall therefore be analyzed, herein. Methods: Serum calretinin (sCRT) was determined by calretinin enzyme-linked immunoabsorbent assay (DLD-Diagnostika GmbH, Hamburg) in a total of 380 serum samples from 134 ovarian cancer patients (thereof n = 115 (86%) with FIGO III or IV), including samples at primary diagnosis and at 4 follow-up reading points in the course of adjuvant treatment. Results: sCRT levels were significantly increased in ovarian cancer patients compared to healthy controls (ED = 0.3ng/ml, p < 0.001) and enabled an accurate discrimination between ovarian cancer and controls (AUC = 0.85). High sCRT levels at primary diagnosis predicted suboptimal debulking surgery without achieving macroscopically complete tumor resection (p < 0.001) and were associated with advanced FIGO-stage (p < 0.001) and high volume of ascites (p < 0.001). Increased sCRT levels at primary diagnosis were an independent predictor of poor PFS (HR:1.99, p = 0.018) and also indicated poor OS (HR:2.49, p = 0.008). Increased sCRT levels before and after platinum-based chemotherapy were independent predictors of poor OS (HR:15.4, p = 0.01; HR:5.59, p = 0.026). Moreover, elevated sCRT levels at primary diagnosis indicated platinum-resistance (p = 0.002). Conclusions: This is the first study, suggesting sCRT as an innovative liquid biopsy marker for ovarian cancer by showing its independent prognostic relevance and its association with primary platinum-resistance.

Clinical relevance of circulating MACC1 and S100A4 transcripts for ovarian cancer

Metastasis‐associated in colon cancer 1 (MACC1) and S100 calcium‐binding protein A4 (S100A4) are prominent inducers of tumor progression and metastasis. For the first time, we systematically tracked circulating serum levels of MACC1 and S100A4 transcripts in the course of surgery and chemotherapy and analyzed their clinical relevance for ovarian cancer. MACC1 and S100A4 transcripts were quantified in a total of 318 serum samples from 79 ovarian cancer patients by RT‐qPCR and digital droplet PCR, respectively. MACC1 and S100A4 transcripts were significantly elevated in serum of ovarian cancer patients, compared to healthy controls (P = 0.024; P < 0.001). At primary diagnosis, high levels of MACC1 or S100A4 correlated with advanced FIGO stage (P = 0.042; P = 0.008), predicted suboptimal debulking surgery and indicated shorter progression‐free survival (PFS; P = 0.003; P = 0.001) and overall survival (OS; P = 0.001; P = 0.002). This is the first study in ovarian cancer to propose circulating MACC1 and S100A4 transcripts as potential liquid biopsy markers.

Abstract P6-09-03: Association of Caspase 8 polymorphisms with TILs and disease-free survival in primary breast cancer patients

BACKGROUND: The minor allele of two caspase-8 polymorphisms, namely CASP8 -652 6N InsDel and CASP8 Asp302His, were shown to promote survival of T-lymphocytes and were repeatedly associated with reduced breast cancer susceptibility. However, besides some preliminary findings, clinical relevance of these polymorphisms in patients with already existing primary breast cancer has not yet been established. Considering an immunomodulatory and potentially tumor-protective role of these caspase-8 variants, we genotyped 785 primary breast cancer patients and correlated caspase-8 variants with i) disease-free survival (DFS) and ii) the presence of tumor infiltrating lymphocytes (TILs).

METHODS: Primary breast cancer samples were collected at the Martin-Luther University, Halle-Wittenberg between 2009 and 2011 as part of the multicenter prospective PiA trial (NCT 01592825). The majority of patients had luminal-like tumors (75.9%), followed by triple negative (10.1%), luminal-Her2-like (9.6%) and Her2-enriched tumors (4.5%). Genotyping was performed by pyrosequencing, TILs status was assessed by hematoxylin and eosin staining.

RESULTS: The CASP8 -652 deletion was significantly associated with improved DFS in an allele-dose dependent manner (p=0.027). Homozygosity for the -652 6N Del variant was an independent predictor for improved DFS (p=0.005). In patients with a 302His/His genotype, there was no event of recurrence during the entire observation time. Combined analysis of diplotypes revealed that both polymorphisms had an influence on DFS (p=0.029). Interestingly, patients with the 302His/His variant among the unstratified patient cohort and among the luminal-like subtype alone had tumors with very low lymphocyte infiltration (0-10% TILs in 65% of cases compared to 31% of cases for other genotypes, p=0.025).

CONCLUSION: In line with previous epidemiological findings, we propose a prognostically favorable role of the CASP8 -652 6N Del and the Asp302His variant in primary breast cancer patients. Moreover, we suggest for the first time a role of the Asp302His variant in immunosurveillance and lymphocyte infiltration of breast cancer. Our findings strongly encourage further analyze of these genetic variants as a biomarker for prognostic and immunotherapeutic considerations.

Citation Format: Wimberger P, Bachmann HS, Kuhlmann JD, Link T, Kröber E, Thomssen C, Malle B, Vetter M, Kantelhardt EJ. Association of Caspase 8 polymorphisms with TILs and disease-free survival in primary 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 P6-09-03.

Extracellular vesicle-associated miRNAs in ovarian cancer – design of an integrated NGS-based workflow for the identification of blood-based biomarkers for platinum-resistance

Background

Extracellular vesicle (EV)-associated microRNAs (miRNAs) have been suggested as promising biomarkers for blood-based cancer diagnosis. However, one of the major limitations for the use of EVs with diagnostic purpose is the lack of standardized EV-profiling techniques. In this regard, the objective of our study was to design an integrated next-generation sequencing (NGS)-based workflow for analyzing the signature of EV-associated miRNA in the plasma of platinum-resistant ovarian cancer patients.

Methods

For EV-extraction, different enrichment methods were compared (ExoQuick vs. exoRNeasy). NGS was performed with the Illumina platform.

Results

We established an integrated NGS-based workflow, including EV-enrichment with the ExoQuick system, which resulted in an optimal RNA-yield and consistent small RNA libraries. We applied this workflow in a pilot cohort of clinically documented platinum-sensitive (n=15) vs. platinum-resistant (n=15) ovarian cancer patients, resulting in a panel of mature EV-associated miRNAs (including ovarian cancer associated miR-181a, miR-1908, miR-21, miR-486 and miR-223), which were differentially abundant in the plasma of platinum-resistant patients.

Conclusions

This is the first study, analyzing the profile of EV-associated miRNAs in platinum-resistant ovarian cancer patients. We provide rationale to further validate these miRNA candidates in an independent set of patients, in order to characterize their biomarker potential as predictors for platinum-resistance.

Precipitation with polyethylene glycol followed by washing and pelleting by ultracentrifugation enriches extracellular vesicles from tissue culture supernatants in small and large scales

Extracellular vesicles (EVs) provide a complex means of intercellular signalling between cells at local and distant sites, both within and between different organs. According to their cell-type specific signatures, EVs can function as a novel class of biomarkers for a variety of diseases, and can be used as drug-delivery vehicles. Furthermore, EVs from certain cell types exert beneficial effects in regenerative medicine and for immune modulation. Several techniques are available to harvest EVs from various body fluids or cell culture supernatants. Classically, differential centrifugation, density gradient centrifugation, size-exclusion chromatography and immunocapturing-based methods are used to harvest EVs from EV-containing liquids. Owing to limitations in the scalability of any of these methods, we designed and optimised a polyethylene glycol (PEG)-based precipitation method to enrich EVs from cell culture supernatants. We demonstrate the reproducibility and scalability of this method and compared its efficacy with more classical EV-harvesting methods. We show that washing of the PEG pellet and the re-precipitation by ultracentrifugation remove a huge proportion of PEG co-precipitated molecules such as bovine serum albumine (BSA). However, supported by the results of the size exclusion chromatography, which revealed a higher purity in terms of particles per milligram protein of the obtained EV samples, PEG-prepared EV samples most likely still contain a certain percentage of other non-EV associated molecules. Since PEG-enriched EVs revealed the same therapeutic activity in an ischemic stroke model than corresponding cells, it is unlikely that such co-purified molecules negatively affect the functional properties of obtained EV samples. In summary, maybe not being the purification method of choice if molecular profiling of pure EV samples is intended, the optimised PEG protocol is a scalable and reproducible method, which can easily be adopted by laboratories equipped with an ultracentrifuge to enrich for functional active EVs.

EMT-like circulating tumor cells in ovarian cancer patients are enriched by platinum-based chemotherapy

Background

Assuming that tumor cell dissemination requires a shift to a mesenchymal phenotype, we analyzed the incidence of epithelial-to-mesenchymal-transition (EMT)-like circulating tumor cells (CTCs) in ovarian cancer patients and inquired, how their molecular phenotypes respond to platinum-based chemotherapy and influence outcome.

Results

Before surgery, overall detection rate for epithelial CTCs was 18%. EMT-like CTCs were more frequently observed (30%) and were mutually exclusive to epithelial CTCs in the majority of patients (82%). After chemotherapy, EMT-like CTCs increased up to 52%, accompanied by the “de novo” emergence of PI3Kα+/Twist+ EMT-like CTCs. Before surgery, PI3K+ EMT-like CTCs in combination with epithelial CTCs indicated decreased OS (p = 0.02) and FIGO I-III patients with residual tumor burden after surgery were more likely to be positive for EMT-like CTCs after chemotherapy (p = 0.02). In the latter group, epithelial CTCs alone significantly correlated with decreased PFS and OS (p = 0.02, p = 0.002), supported by an additional inclusion of PI3K+ CTCs (OS, p = 0.001).

Materials and Methods

Blood samples of 91 ovarian cancer patients before surgery and 31 matched samples after adjuvant chemotherapy were evaluated for CTCs with the AdnaTest ovarian cancer and EMT-1, analyzing the epithelial-associated transcripts EpCAM, Muc-1 and CA125 and the EMT-associated transcripts PI3Kα, Akt-2 and Twist.

Conclusions

Platinum-based chemotherapy seems to select for EMT-like CTCs in ovarian cancer patients and provokes a shift towards PI3Kα and Twist expressing CTCs, which may reflect clonal tumor evolution towards therapy resistance. It has to be determined, whether this CTC subgroup may serve as a biomarker to identify patients at high risk.

A Subpopulation of Stromal Cells Controls Cancer Cell Homing to the Bone Marrow

Breast and prostate cancer cells home to the bone marrow, where they presumably hijack the hematopoietic stem cell niche. We characterize here the elusive premetastatic niche by examining the role of mesenchymal stromal cells (MSC) in cancer cell homing. Decreasing the number of MSC pharmacologically enhanced cancer cell homing to the bone marrow in mice. In contrast, increasing the number of these MSCs by various interventions including G-CSF administration diminished cancer cell homing. The MSC subpopulation that correlated best with cancer cells expressed stem, endothelial, and pericytic cell markers, suggesting these cells represent an undifferentiated component of the niche with vascular commitment. In humans, a MSC subpopulation carrying markers for endothelial and pericytic cells was lower in the presence of cytokeratin⁺ cells in bone marrow. Taken together, our data show that a subpopulation of MSC with both endothelial and pericytic cell surface markers suppresses the homing of cancer cells to the bone marrow. Similar to the presence of cytokeratin⁺ cells in the bone marrow, this MSC subpopulation could prove useful in determining the risk of metastatic disease, and its manipulation might offer a new possibility for diminishing bone metastasis formation.Significance: These findings establish an inverse relationship between a subpopulation of mesenchymal stromal cells and cancer cells in the bone marrow. Cancer Res; 78(1); 129-42. ©2017 AACR.

The conjugated antimetabolite 5-FdU-ECyd and its cellular and molecular effects on platinum-sensitive vs. -resistant ovarian cancer cells in vitro

Background

Resistance to platinum-based chemotherapy is a clinical challenge in the treatment of ovarian cancer (OC) and limits survival. Therefore, innovative drugs against platinum-resistance are urgently needed. Our therapeutic concept is based on the conjugation of two chemotherapeutic compounds to a monotherapeutic pro-drug, which is taken up by cancer cells and cleaved into active cytostatic metabolites. We explore the activity of the duplex-prodrug 5-FdU-ECyd, covalently linking 2'-deoxy-5-fluorouridine (5-FdU) and 3'-C-ethynylcytidine (ECyd), on platinum-resistant OC cells.

Methods

In vitro assays and RNA-Sequencing were applied for characterization of 5-FdU-ECyd treated platinum-sensitive A2780 and isogenic platinum-resistant A2780cis and independent platinum-resistant Skov-3-IP OC cells.

Results

Nano molar 5-FdU-ECyd concentrations induced a rapid dose-dependent decline of cell viability in platinum-sensitive and -resistant OC cells. The effect of 5-FdU-ECyd was accompanied by the formation of DNA double strand breaks and apoptosis induction, indicated by a strong increase of pro-apoptotic molecular markers. Moreover, 5-FdU-ECyd efficiently decreased migration of platinum-resistant OC cells and inhibited clonogenic or spheroidal growth. Transcriptome analysis showed early up-regulation of CDKN1A and c-Fos in both, platinum-resistant and -sensitive cells after 5-FdU-ECyd treatment and de-regulation of distinct cellular pathways involved in cell cycle regulation, apoptosis, DNA-damage response and RNA-metabolism. Combined treatment of 5-FdU-ECyd and cisplatin did not show a synergistic cellular response, suggesting the potential use of 5-FdU-ECyd as a monotherapeutic agent.

Conclusion

Our data provide novel mechanistic insight into the anti-tumor effect of 5-FdU-ECyd and we hypothesize that this duplex-prodrug could be a promising therapeutic option for OC patients with resistance to platinum-based chemotherapy.

The activity of the conjugated antimetabolite 5-FdU-ECyd against platinum-resistant ovarian cancer

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Background: Primary or secondary resistance to platinum-based chemotherapy is an important clinical challenge in the treatment of ovarian cancer (OC) and limits survival. Therefore, the development of innovative drugs against platinum resistance is urgently needed. Our therapeutic concept is based on the conjugation of two chemotherapeutic compounds to a monotherapeutic pro-drug, which is taken up by cancer cells and is subsequently cleaved into several active cytostatic metabolites. Our in vitro study evaluates the effects of the conjugated antimetabolite 5-FdU-ECyd, consisting of 2-deoxy-5-fluorouridine (5-FdU) and ethynylcytidine (ECyd), on platinum-resistant OC cells. Methods: In vitro assays and RNA-Seq (Illumina) were applied for characterization of 5-FdU-ECyd treated platinum-sensitive A2780 and isogenic platinum-resistant A2780cis as well as independent platinum-resistant Skov-3-IP OC cells. Results: Nano molar 5-FdU-ECyd concentrations induced a rapid dose-dependent decline of cell viability in platinum-sensitive and platinum-resistant OC cells. The cytotoxicity of 5-FdU-ECyd was accompanied by the formation of DNA double strand breaks and by the induction of apoptosis, indicated by a strong increase of pro-apoptotic molecular markers (caspase-3/7 activation, PARP-cleavage). Moreover, 5-FdU-ECyd efficiently decreased cell migration of platinum-resistant OC cells and inhibited other tumor-associated cellular functions, such as clonogenic or spheroidal growth. Transcriptome analysis indicated that, independently of platinum-resistance status, 5-FdU-ECyd influences distinct cellular pathways, involved in cell cycle regulation, apoptosis, DNA-damage response and RNA/pyrimidine metabolism. Combination treatment of 5-FdU-ECyd and platin did not show a synergistic cellular response, suggesting the potential use of 5-FdU-ECyd as a monotherapeutic agent. Conclusions: Our data provide a rationale to characterize the effect of 5-FdU-ECyd in a pre-clinical in vivo setting. We hypothesize that this conjugate is a promising therapeutic option for OC patients with resistance to conventional platinum-based chemotherapy.

ERCC1-expressing circulating tumor cells as a potential diagnostic tool for monitoring response to platinum-based chemotherapy and for predicting post-therapeutic outcome of ovarian cancer

BACKGROUND

We recently showed that the presence of ERCC1+CTCs is an independent predictive biomarker for platinum-resistance and poor prognosis of ovarian cancer. The goal of our current research was to determine how the auxiliary assessment of ERCC1-transcripts influences overall CTC-detection rate. We extended this investigation from an initially predictive setting to paired pre- and post-therapeutic blood analysis in order to see, whether ERCC1+CTCs dynamics mirror response to chemotherapy.

METHODS

65 Paired blood samples (10ml) of primary ovarian cancer patients at primary diagnosis and after chemotherapy were studied for CTCs with the AdnaTest Ovarian Cancer (QIAGEN Hannover GmbH). We analyzed the tumor-associated transcripts EpCAM, MUC-1 and CA-125. ERCC1-transcripts were investigated in a separate approach by singleplex RT-PCR.

RESULTS

Auxiliary assessment of ERCC1-transcripts enhanced the overall CTC-detection rate up to 17%. ERCC1+CTCs (defined as positive for one of the AdnaTest markers plus ERCC1-positivity) were detected in 15% of patients at primary diagnosis and in 12% after chemotherapy. The presence of ERCC1+CTCs after chemotherapy correlated with platinum-resistance (P=0.01), reduced PFS (P=0.0293) and OS (P=0.0008) and their persistence indicated poor post-therapeutic outcome (PFS: P=0.005; OS: P=0.0058). Interestingly, the assessment of ERCC1-transcripts alone was sufficient for the detection of prognostic relevant ERCC1-expressing CTCs.

CONCLUSION

Auxiliary assessment of ERCC1-transcripts expands the phenotypic spectrum of CTC detection and defines an additional overlapping fraction of ERCC1-expressing CTCs, which are potentially selected by platinum-based chemotherapy. Specifically, we suggest that ERCC1+CTCs could additionally be useful as a surrogate for monitoring platinum-based chemotherapy and to assess the post-therapeutic outcome of ovarian cancer.

ERCC1-expressing circulating tumor cells as a potential diagnostic tool for monitoring response to platinum-based chemotherapy and for predicting post-therapeutic outcome of ovarian cancer

BACKGROUND

We recently showed that the presence of ERCC1+CTCs is an independent predictive biomarker for platinum-resistance and poor prognosis of ovarian cancer. The goal of our current research was to determine how the auxiliary assessment of ERCC1-transcripts influences overall CTC-detection rate. We extended this investigation from an initially predictive setting to paired pre- and post-therapeutic blood analysis in order to see, whether ERCC1+CTCs dynamics mirror response to chemotherapy.

METHODS

65 Paired blood samples (10ml) of primary ovarian cancer patients at primary diagnosis and after chemotherapy were studied for CTCs with the AdnaTest Ovarian Cancer (QIAGEN Hannover GmbH). We analyzed the tumor-associated transcripts EpCAM, MUC-1 and CA-125. ERCC1-transcripts were investigated in a separate approach by singleplex RT-PCR.

RESULTS

Auxiliary assessment of ERCC1-transcripts enhanced the overall CTC-detection rate up to 17%. ERCC1+CTCs (defined as positive for one of the AdnaTest markers plus ERCC1-positivity) were detected in 15% of patients at primary diagnosis and in 12% after chemotherapy. The presence of ERCC1+CTCs after chemotherapy correlated with platinum-resistance (P=0.01), reduced PFS (P=0.0293) and OS (P=0.0008) and their persistence indicated poor post-therapeutic outcome (PFS: P=0.005; OS: P=0.0058). Interestingly, the assessment of ERCC1-transcripts alone was sufficient for the detection of prognostic relevant ERCC1-expressing CTCs.

CONCLUSION

Auxiliary assessment of ERCC1-transcripts expands the phenotypic spectrum of CTC detection and defines an additional overlapping fraction of ERCC1-expressing CTCs, which are potentially selected by platinum-based chemotherapy. Specifically, we suggest that ERCC1+CTCs could additionally be useful as a surrogate for monitoring platinum-based chemotherapy and to assess the post-therapeutic outcome of ovarian cancer.

Suppression of indoleamine-2,3-dioxygenase 1 expression by promoter hypermethylation in ER-positive breast cancer

Kynurenine formation by tryptophan-catabolic indoleamine-2,3-dioxygenase 1 (IDO1) plays a key role in tumor immune evasion and inhibition of IDO1 is efficacious in preclinical models of breast cancer. As the response of breast cancer to immune checkpoint inhibitors may be limited, a better understanding of the expression of additional targetable immunomodulatory pathways is of importance. We therefore investigated the regulation of IDO1 expression in different breast cancer subtypes. We identified estrogen receptor α (ER) as a negative regulator of IDO1 expression. Serum kynurenine levels as well as tumoral IDO1 expression were lower in patients with ER-positive than ER-negative tumors and an inverse relationship between IDO1 and estrogen receptor mRNA was observed across 14 breast cancer data sets. Analysis of whole genome bisulfite sequencing, 450k, MassARRAY and pyrosequencing data revealed that the IDO1 promoter is hypermethylated in ER-positive compared with ER-negative breast cancer. Reduced induction of IDO1 was also observed in human ER-positive breast cancer cell lines. IDO1 induction was enhanced upon DNA demethylation in ER-positive but not in ER-negative cells and methylation of an IDO1 promoter construct reduced IDO1 expression, suggesting that enhanced methylation of the IDO1 promoter suppresses IDO1 in ER-positive breast cancer. The association of ER overexpression with epigenetic downregulation of IDO1 appears to be a particular feature of breast cancer as IDO1 was not suppressed by IDO1 promoter hypermethylation in the presence of high ER expression in cervical or endometrial cancer.

Prognostic relevance of caspase 8 -652 6N InsDel and Asp302His polymorphisms for breast cancer

Background

The minor allele of two caspase 8 polymorphisms, namely CASP8 -652 6N InsDel (rs3834129) and CASP8 Asp302His (rs1045485), were repeatedly associated with reduced breast cancer susceptibility. Contrarily, the presence of the -652 6N Del or the CASP8 302His variant was reported to be an unfavorable prognostic factor in colorectal cancer or neuroblastoma. However, prognostic relevance of these genetic variants for breast cancer is completely unknown and is therefore adressed by the current study.

Methods

Genotyping was performed by pyrosequencing. Caspase 8 mRNA expression was quantified by comparative RT-qPCR.

Results

We observed an allele-dose dependent association between CASP8 -652 6N InsDel and caspase 8 mRNA expression in breast cancer tissue, with homozygous deletion carriers showing lowest relative caspase 8 expression (p = 0.0131). Intriguingly, the presence of the -652 6N Del or the 302His variant was shown to be a negative prognostic factor for breast cancer in terms of an allele-dose dependent influence on overall survival (OS, p = 0.0018, p = 0.0150, respectively). Moreover, both polymorphisms were independent predictors of OS after adjusting for co-variats (p = 0.007, p = 0.037, respectively). Prognostic relevance of both polymorphisms were confirmed to be independent from each other and combined analysis of diplotypes revealed an additive influence upon OS (p = 0.0002).

Conclusion

This is the first report, showing negative and independent prognostic impact of the CASP8 -652 6N Del and the 302His variant for breast cancer. Our data provide rationale to further validate clinical utility of these polymorphisms for breast cancer and to extend this investigation to a broad scope of other malignancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2662-x) contains supplementary material, which is available to authorized users.

Identification and Functional Testing of ERCC2 Mutations in a Multi-national Cohort of Patients with Familial Breast- and Ovarian Cancer

The increasing application of gene panels for familial cancer susceptibility disorders will probably lead to an increased proposal of susceptibility gene candidates. Using ERCC2 DNA repair gene as an example, we show that proof of a possible role in cancer susceptibility requires a detailed dissection and characterization of the underlying mutations for genes with diverse cellular functions (in this case mainly DNA repair and basic cellular transcription). In case of ERCC2, panel sequencing of 1345 index cases from 587 German, 405 Lithuanian and 353 Czech families with breast and ovarian cancer (BC/OC) predisposition revealed 25 mutations (3 frameshift, 2 splice-affecting, 20 missense), all absent or very rare in the ExAC database. While 16 mutations were unique, 9 mutations showed up repeatedly with population-specific appearance. Ten out of eleven mutations that were tested exemplarily in cell-based functional assays exert diminished excision repair efficiency and/or decreased transcriptional activation capability. In order to provide evidence for BC/OC predisposition, we performed familial segregation analyses and screened ethnically matching controls. However, unlike the recently published RECQL example, none of our recurrent ERCC2 mutations showed convincing co-segregation with BC/OC or significant overrepresentation in the BC/OC cohort. Interestingly, we detected that some deleterious founder mutations had an unexpectedly high frequency of > 1% in the corresponding populations, suggesting that either homozygous carriers are not clinically recognized or homozygosity for these mutations is embryonically lethal. In conclusion, we provide a useful resource on the mutational landscape of ERCC2 mutations in hereditary BC/OC patients and, as our key finding, we demonstrate the complexity of correct interpretation for the discovery of “bonafide” breast cancer susceptibility genes.

Approximately 5–10% of breast/ovarian cancer (BC/OC) cases have inherited an increased risk of developing this malignancy. However, mutations in the two major breast cancer susceptibility genes BRCA1 and BRCA2 explain only 15–20% of all familial BC/OC cases. With the emergence of the high throughput NGS-technology, the number of proposed novel candidate genes for breast cancer predisposition continuously increases. However, a “bonafide” proof of cancer susceptibility requires a detailed characterization of candidate mutations, which we addressed in the current study. Using the DNA repair gene ERCC2 as an example, we performed a comprehensive multi-center approach, analyzing ERCC2 mutations in 1000+ patients with hereditary BC/OC. We identified 25 potential candidate mutations for cancer breast cancer susceptibility, some of them affecting ERCC2 functional activity in appropriate cell-culture based assays. However, a more dissected analysis showed no convincing co-segregation with BC/OC and there was no longer a significant overrepresentation in BC/OC when compared to regionally matched controls instead of the global ExAc variant data base, pointing to the relevance of founder-mutations. In conclusion, we provide a useful resource on the mutational landscape of ERCC2 mutations in hereditary BC/OC patients and, as our key finding, we highlight the complexity of correct interpretation for the discovery of “bonafide” breast cancer susceptibility genes.

Abstract 447: The presence and persistence of ERCC1 positive circulating tumor cells predicts worse prognosis in primary ovarian cancer patients

Background: Resistance to platinum based chemotherapy in ovarian cancer can only be assessed retrospectively during post-chemotherapy follow-up. We recently showed that excision-repair cross-complementing rodent repair deficiency complementation group 1 nuclease (ERCC1)-positive (+) circulating tumor cells (CTCs) were an independent predictor for progression free survival (PFS), overall survival (OS) and for platinum-resistance in our ovarian cancer patients (pts). We now analyzed whether the negative prognostic impact of CTCs was related to the presence and persistence of ERCC1+ CTCs after platinum based chemotherapy.

Methods: 10 ml blood of 65 primary ovarian cancer pts before and after chemotherapy were studied for CTCs by immunomagnetic enrichment followed by multiplex RT-PCR to detect the transcripts EpCAM, MUC-1 and Ca 125 (AdnaTest OvarianCancer; QIAGEN Hannover GmbH, Germany). A patient was considered CTC+, if at least one of the three markers was detectable. ERCC1 was analyzed in a separate approach by single plex PCR, ß-actin served as an internal control and PCR-products were quantified on the Agilent Bioanalyzer 2100.

Results: CTCs were detected in 18/65 pts (28%) before and in 13/65 pts (20%) after chemotherapy. A persistence of CTCs was found in four pts, 14 pts were only positive before and nine pts only after therapy whereas in 38 pts, no CTCs were detected at any time. Pts with persisting CTCs had a significantly shorter PFS (p = 3.32E-05) and OS (0.00018) while pts initially CTC-negative before but CTC+ after therapy showed a reduced OS (p = 0.0039). ERCC1+CTCs were observed in 12/65 (18%) pts before and in 8/65 pts (12%) after therapy. A persistence of ERCC1+CTCs was found in three pts, nine pts were only positive before, five pts only after therapy whereas in 48 pts, no ERCC1+CTCs were detected at any time. Pts with persisting ERCC1+CTCs had a significantly shorter PFS (p = 0.032) and OS (0.0058) while pts initially ERCC1-negative before but ERCC1+ after therapy showed a reduced OS (p = 0.039). Up to now, no association between clinically defined platinum resistance and ERCC1-positivity was observed.

Conclusion: The negative prognostic impact of CTCs was related to the presence and persistence of ERCC1+CTCs after therapy supporting the idea to implement ERCC1 expression in CTC analysis of ovarian cancer pts as a biomarker for monitoring the disease to possibly change treatment in case of ERCC1 persistent CTCs.

Citation Format: Issam Chebouti, Paul Buderath, Jan Dominik Kuhlmann, Yvonne Bokeloh, Siggi Hauch, Rainer Kimmig, Sabine Kasimir-Bauer. The presence and persistence of ERCC1 positive circulating tumor cells predicts worse prognosis in primary ovarian cancer patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 447.

Gene expression profiling of single circulating tumor cells in ovarian cancer - Establishment of a multi-marker gene panel

The presence of circulating tumor cells (CTCs) in the blood of ovarian cancer patients was shown to correlate with decreased overall survival, whereby CTCs with epithelial-mesenchymal-transition (EMT) or stem-like traits are supposed to be involved in metastatic progression and recurrence. Thus, investigating the transcriptional profiles of CTCs might help to identify therapy resistant tumor cells and to overcome treatment failure. For this purpose, we established a multi-marker panel for the molecular characterization of single CTCs, detecting epithelial (EpCAM, Muc-1, CK5/7), EMT (N-cadherin, Vimentin, Snai1/2, CD117, CD146, CD49f) and stem cell (CD44, ALDH1A1, Nanog, SOX2, Notch1/4, Oct4, Lin28) associated transcripts. First primer specificity and PCR-performance of the multiplex-RT-PCRs were successfully validated on genomic DNA and cDNA isolated from OvCar3 cells. The assay sensitivity of the epithelial panel was evaluated by adding defined numbers of tumor cells into the blood of healthy donors and performing a subsequent immunomagnetic tumor cell enrichment (AdnaTest OvarianCancerSelect), resulting in a 100% concordance for the epithelial markers EpCAM and Muc-1 to the AdnaTest OvarianCancerDetect. Additionally, by processing blood from ovarian cancer patients, high assay sensitivity could be verified. In blood of healthy donors no signals for epithelial markers were detected, for EMT and stem cell markers, however, signals were obtained mainly originating from leukocytes which calls for single cell analysis. To that aim by using the ovarian cancer cell line OvCar3, we successfully established a workflow enabling the characterization of single CTCs. It consists of a density gradient-dependent enrichment for nucleated cells, a depletion of CD45-positive cells of hematopoietic origin followed by immunofluorescent labeling of CTCs by EpCAM and Muc-1. Single CTCs are then isolated by micromanipulation and processed for panel gene expression profiling. Finally, fifteen single CTCs from three ovarian cancer patients were analyzed and found to be positive for stem cell (CD44, ALDH1A1, Nanog, Oct4) and EMT markers (N-cadherin, Vimentin, Snai2, CD117, CD146). Albeit, inter-cellular and intra/inter-patient heterogeneity and co-expression of epithelial, mesenchymal and stem cell transcripts on the same CTC was observed. We have established a robust workflow to perform sensitive single cell panel gene expression analysis without the need of pre-amplification steps. Our data point towards a heterogeneous expression of stem cell and EMT associated transcripts in ovarian cancer CTCs.