Baseline Circulating Tumor Cells Research Articles

An Australian Three-Centre Feasibility Study of Neoadjuvant Modified FOLFIRINOX and Stereotactic Body Radiotherapy for Locally Advanced Pancreatic Cancer with Collection of Baseline Circulating Tumor Cells

Stereotactic body radiotherapy (SBRT) has an increasing role for treatment of locally advanced pancreatic adenocarcinoma (LAPC). Selection of appropriate cases may be improved with identification of useful prognostic and predictive clinical biomarkers. This study aimed to establish the feasibility and safety of neoadjuvant modified FOLFIRINOX (mFOLFIRINOX) chemotherapy followed by SBRT for patients with LAPC (including borderline resectable), and to identify a role for circulating tumor cells (CTCs) in prognostication. Eligible patients were enrolled to a three-center prospective pilot study (MASTERPLAN Pilot ACTRN12617001642370). Eligibility criteria included age > 18 years, histological confirmation of PA, ECOG 0-1, with confirmation of borderline resectable (BRPC) or unresectable LAPC according to NCCN guidelines. The initial patient cohort was enrolled in a sub-study, to collect peripheral blood CTCs at baseline (bCTCs) which was correlated with overall survival (OS), progression free survival (PFS) and locoregional relapse free survival (LRFS). Patients received 4 cycles of mFOLFIRINOX (oxaliplatin, irinotecan, 5-fluorouracil), followed by insertion of pancreatic fiducials and 5 fractions of SBRT to a dose of 30Gy with a simultaneous integrated boost to 45Gy, determined by proximity to organs at risk. Acute toxicity was collected to 3 months post-SBRT. Between April 2018 and October 2019, 12 patients were enrolled (initial 10 to the bCTC sub-study). The median follow-up from diagnosis was 10 months (range 4-18). Three patients did not commence treatment after enrollment, and 2 patients did not proceed to SBRT after mFOLFIRINOX. Seven patients with a median age of 62 years completed trial therapy. The median CA19.9 at baseline was 225kU/L (range 1-2558), 72% had BRPC and 57% were lymph node positive. One patient with BRPC proceeded to resection with positive surgical margins. At the time of evaluation, two further patients with BRPC were awaiting re-evaluation prior to surgery. Of those alive at 6 and 12 months follow up, local control was achieved in 83.3% and 66.7% of patients respectively. The first patient experienced acute Grade 3 neutropenia. Thereafter, G-CSF was administered with mFOLFIRINOX and no further Grade 3 toxicities were seen. Six patients experienced Grade 2 acute toxicity, and no patients developed Grade 4 toxicity. Nine patients had bCTCs collected, and of these, 6 completed trial therapy. The median number of CTCs was 11 per 8mls blood (range 1-12), and in this study bCTCs did not significantly correlate with OS, PFS or LRFS, however due to small numbers interpretation of this data is limited. Neoadjuvant mFOLFIRINOX with G-CSF and SBRT to 30-45Gy is feasible and safe. A role of bCTCs in prognostication was not identified in this small study.

Blood-based gene expression signature associated with metastatic castrate-resistant prostate cancer patient response to abiraterone plus prednisone or enzalutamide.

Precision medicine approaches for managing patients with metastatic castrate-resistant prostate cancer (mCRPC) are lacking. Non-invasive approaches for molecular monitoring of disease are urgently needed, especially for patients suffering from bone metastases for whom tissue biopsy is challenging. Here we utilized baseline blood samples to identify mCRPC patients most likely to benefit from abiraterone plus prednisone (AAP) or enzalutamide. Baseline blood samples were collected for circulating tumor cell (CTC) enumeration and qPCR-based gene expression analysis from 51 men with mCRPC beginning treatment with abiraterone or enzalutamide. Of 51 patients (median age 68 years [51-82]), 22 received AAP (abiraterone 1000 mg/day plus prednisone 10 mg/day) and 29 received enzalutamide (160 mg/day). The cohort was randomly divided into training (n = 37) and test (n = 14) sets. Baseline clinical variables (Gleason score, PSA, testosterone, and hemoglobin), CTC count, and qPCR-based gene expression data for 141 genes/isoforms in CTC-enriched blood were analyzed with respect to overall survival (OS). Genes with expression most associated with OS included MSLN, ARG2, FGF8, KLK3, ESRP2, NPR3, CCND1, and WNT5A. Using a Cox-elastic net model for our test set, the 8-gene expression signature had a c-index of 0.87(95% CI [0.80, 0.94]) and was more strongly associated with OS than clinical variables or CTC count alone, or a combination of the three variables. For patients with a low-risk vs. high-risk gene expression signature, median OS was not reached vs. 18 months, respectively (HR 5.32 [1.91-14.80], p = 0.001). For the subset of 41 patients for whom progression-free survival (PFS) data was available, the median PFS for patients with a low-risk vs high-risk gene expression signature was 20 vs. 5 months, respectively (HR 2.95 [1.46-5.98], p = 0.003). If validated in a larger prospective study, this test may predict patients most likely to benefit from second-generation antiandrogen therapy.

Serial Analysis of Circulating Tumor Cells in Metastatic Breast Cancer Receiving First-Line Chemotherapy.

We examined the prognostic significance of circulating tumor cell (CTC) dynamics during treatment in metastatic breast cancer (MBC) patients receiving first-line chemotherapy. Serial CTC data from 469 patients (2202 samples) were used to build a novel latent mixture model to identify groups with similar CTC trajectory (tCTC) patterns during the course of treatment. Cox regression was used to estimate hazard ratios for progression-free survival (PFS) and overall survival (OS) in groups based on baseline CTCs, combined CTC status at baseline to the end of cycle 1, and tCTC. Akaike information criterion was used to select the model that best predicted PFS and OS. Latent mixture modeling revealed 4 distinct tCTC patterns: undetectable CTCs (56.9% ), low (23.7%), intermediate (14.5%), or high (4.9%). Patients with low, intermediate, and high tCTC patterns had statistically significant inferior PFS and OS compared with those with undetectable CTCs (P < .001). Akaike Information Criterion indicated that the tCTC model best predicted PFS and OS compared with baseline CTCs and combined CTC status at baseline to the end of cycle 1 models. Validation studies in an independent cohort of 1856 MBC patients confirmed these findings. Further validation using only a single pretreatment CTC measurement confirmed prognostic performance of the tCTC model. We identified 4 novel prognostic groups in MBC based on similarities in tCTC patterns during chemotherapy. Prognostic groups included patients with very poor outcome (intermediate + high CTCs, 19.4%) who could benefit from more effective treatment. Our novel prognostic classification approach may be used for fine-tuning of CTC-based risk stratification strategies to guide future prospective clinical trials in MBC.

Clinical Correlations of Programmed Cell Death Ligand 1 Status in Liquid and Standard Biopsies in Breast Cancer.

Data regarding the prognostic value of programmed cell death ligand 1 (PD-L1) expression on circulating tumor cells (CTCs) are lacking. However, CTCs could represent an alternative approach to serial biopsies, allowing real-time monitoring of cancer phenotype. We evaluated, in a dedicated prospective clinical trial, the clinicopathological correlations and prognostic value of PD-L1(+)-CTCs in 72 patients with metastatic breast cancer (MBC). Eighteen of 56 patients with available archival tissue presented at least one positive (≥1%) PD-L1 tumor sample. Baseline CTCs and PD-L1(+)-CTCs were detected in 57 (79.2%) and 26 (36.1%) patients. No significant correlation was found between PD-L1 tumors and CTC expression. In univariate analysis, triple negative (TN) phenotype, number of metastatic treatments, >2 metastatic sites, ≥5 CTCs and PD-L1(+)-CTCs were significantly associated with progression-free survival, while tissue PD-L1 expression was not. In multivariate analysis, TN phenotype, number of metastatic treatments and of metastatic sites were the only 3 variables independently associated with progression-free survival. Progesterone receptor negativity, TN phenotype, >2 metastatic sites and ≥5 CTCs were significantly associated with overall survival in univariate analysis. In multivariable analysis, TN phenotype and >2 metastatic sites were the only 2 independent variables. Unlike PD-L1(+)-tumor, PD-L1(+)-CTCs correlate to survival in MBC. Reappraisal of the role of PD-L1 expression by tumor tissue and by CTCs under anti-PD-1/PD-L1 treatment is necessary to evaluate its predictive value and potential role as a stratifying factor in strategies and trials for MBC patients with MBC. NCT02866149.

Baseline circulating tumor cell (CTC) count as a prognostic marker of PSA response and progression in metastatic castrate sensitive prostate cancer (mCSPC): Results from SWOG S1216, a phase III randomized trial of androgen deprivation plus orteronel (cyp17 inhibitor) or bicalutamide.

5506 Background: In mCSPC, androgen deprivation therapy (ADT) combined with chemotherapy or androgen receptor signaling inhibition (ARSI) is the new standard of care. Biomarkers that predict clinical outcomes with these therapies are needed. We hypothesized that CellSearch CTC count, an FDA-cleared biomarker in metastatic castrate resistant PC (mCRPC), may be a valuable biomarker in mCSPC. Methods: In S1216, peripheral blood was drawn with informed consent at registration (baseline), and CTCs were enumerated on the FDA-cleared CellSearch platform (Menarini) per standard manufacturer protocol. CTC counts were analyzed centrally for associations with 2 pre-specified trial intermediate endpoints: 7-month PSA (7mPSA) ≤ 0.2 ng/ml vs. 0.2–4.0 vs. &gt; 4.0, (intermediate endpoint for overall survival, OS); and progression-free survival (PFS) &lt; vs. &gt; 2 years. Because OS data have not matured, analysis was pooled and equal numbers of samples were analyzed from each treatment arm and outcome measure (7mPSA and PFS) as stipulated by the Data Safety Monitoring Committee. Results: From 2014 to 2017, 523 baseline samples were collected. In the 7mPSA analysis (n = 264), CTCs were detected in 38% of men, with a median of 4 CTCs in those with detectable CTCs. In the PFS analysis (n = 336), CTCs were detected in 37% of men, with a median of 3 CTCs in those with detectable CTCs. Adjusting for disease burden (minimal vs. extensive) and ADT status (already initiated or not) at the time of CTC measurement, men with undetectable CTCs were 6.1-fold more likely to attain 7mPSA ≤ 0.2 (OR 6.1, 95% CI 2.1-17.2, p &lt; 0.001) and 3.7-fold more likely to achieve &gt; 2 years PFS (OR 3.7, 95% CI 1.7-8.1, p &lt; 0.001) compared to men with baseline CTCs ≥ 5. Other cutpoints previously validated in mCRPC studies (CTC &lt; 5 vs. ≥5 and CTCs 0 vs. ≥1) also strongly discriminated 7mPSA and PFS with statistical significance in this mCSPC cohort. Conclusions: CTC count at the start of treatment for mCSPC was highly prognostic of 7-month PSA response (intermediate endpoint for OS) and of PFS at 2 years. To our knowledge, this is the first such strong evidence from a prospective phase 3 trial of this magnitude. Additional analyses are planned when the trial is fully reported. Baseline CTC count may serve as a valuable prognostic marker to discriminate men likely to respond favorably to hormonal therapies from those who may benefit from early alternate interventions.

Circulating Tumor Cells and Early Relapse in Node-positive Melanoma.

There is a need for sensitive, reproducible biomarkers for patients with stage III melanoma to guide clinical decision making. Circulating tumor cells (CTCs) can be detected in patients with melanoma; however, there are limited data regarding their significance in stage III disease. The aim of this study was to determine whether CTCs are associated with early relapse in stage III melanoma. We prospectively assessed CTCs at first presentation in clinic (baseline) for 243 patients with stage III melanoma. CTCs were measured using the CellSearch System. Relapse-free survival (RFS) was compared between patients with one or more baseline CTC versus those with no CTCs. Log-rank test and Cox regression analysis were applied to establish associations of CTCs with RFS. At least one baseline CTC was identified in 90 of 243 (37%) patients. Forty-five (19%), 67 (28%), 118 (49%), and 13 (5%) patients were stage IIIA, IIIB, IIIC, or IIID, respectively. CTC detection was not associated with substage, or primary tumor characteristics. Multivariable analysis demonstrated that the detection of ≥1 baseline CTC was significantly associated with decreased 6-month RFS [log-rank, P < 0.0001; HR, 3.62, 95% confidence interval (CI), 1.78-7.36; P < 0.0001] and 54-month RFS (log-rank, P = 0.01; HR, 1.69; 95% CI, 1.13-2.54; P = 0.01). ≥1 CTC was independently associated with melanoma relapse, suggesting that CTC assessment may be useful to identify patients at risk for relapse who could derive benefit from adjuvant therapy.

Association Between Baseline Circulating Tumor Cells, Molecular Tumor Profiling, and Clinical Characteristics in a Large Cohort of Chemo-naïve Metastatic Colorectal Cancer Patients Prospectively Collected

BackgroundClinicopathologic characteristics and prognostic and predictive factors offer valuable guidance when selecting optimal first-line treatment in patients with metastatic colorectal cancer (CRC). The association between baseline circulating tumor cell (bCTC) count, molecular tumor profile, and clinicopathologic features was analyzed in a chemo-naïve metastatic CRC population. Patients and MethodsA total of 1202 patients from the Spanish VISNÚ-1 (FOLFIRINOX/bevacizumab vs. FOLFOX/bevacizumab) and VISNÚ-2 (FOLFIRI/bevacizumab vs. FOLFIRI/cetuximab; RAS-wildtype) studies were analyzed for mutational status and bCTC count. The association between clinicopathologic characteristics and bCTC count, mutational status, and microsatellite instability (MSI) was analyzed in 589 eligible patients. ResultsInterestingly, 41% of the population studied presented ≥3 bCTC count. bCTC count ≥3 was associated with worse performance status (according Eastern Cooperative Oncology Group scale), stage IV at diagnosis, at least 3 metastatic sites, and elevated carcinoembryonic antigen (CEA) levels; but not with RAS or BRAF mutations or high MSI. BRAFmut (BRAF mutated) tumors were associated with right-sided primary tumors, peritoneum, distant lymph node metastasis, and less frequent liver involvement. RASmut (RAS mutated) was associated with worse performance status; stage IV at diagnosis; right-sided primary tumors; liver, lung, and bone metastases; at least 3 metastatic sites; and elevated CEA, whereas PIK3CAmut (PIK3CA mutated) tumors were associated with right-sided primary tumors, high CEA serum levels, and older age. High MSI was associated with right-sided primary tumors, distant lymph nodes metastasis, and lower CEA levels. ConclusionsIn our study, elevated bCTCs and RASmut were associated with clinicopathologic features known to be associated with poor prognosis; whereas the poor prognosis of BRAFmut tumors in chemo-naïve metastatic CRC is not explained by associations with poor clinicopathologic prognostic factors, except right-sided primary tumors. Trial registration numberVISNU 1 ClinicalTrials.gov ID: NCT01640405/ VISNU 2 ClinicalTrials.gov ID: NCT01640444

Niraparib in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) and biallelic DNA-repair gene defects (DRD): Correlative measures of tumor response in phase II GALAHAD study.

118 Background: Niraparib, a highly potent and selective poly (ADP-ribose) polymerase inhibitor (PARPi) received breakthrough designation by US FDA for treatment of pts with BRCA1,2 mutant mCRPC who progressed on taxane and androgen receptor-targeted therapy. Circulating tumor cells (CTC) detection associates with poor outcomes, with declining counts consistent with improved survival [1,2]. Methods: GALAHAD study assessed niraparib (300 mg daily) in pts with mCRPC+DRD (NCT02854436). Patients with non-measurable soft tissue disease by RECIST 1.1 were required to have a baseline CTC count ≥1 cell/7.5 mL blood. CTC response was defined as CTC conversion to &lt;5 for pts with baseline CTC≥5 and CTC drop to 0 post-baseline for pts with ≥1 baseline CTC. Alkaline phosphatase (ALP) was collected at each monthly cycle. Results: For primary efficacy population of pts with BRCA1/2 mutations, the objective response rate (ORR) by RECIST 1.1 criteria was 41.4%. CTC response rates for this population were as high as ORR regardless of measurability (Table). Time to CTC response for each CTC responder will be shown. Radiographic progression-free survival (rPFS) durations were similar for patients with a measurable disease response and patients with CTC conversion. Median duration of treatment for responders of any type was 6.7mo (range: 2–27). DRD status, both BRCA and non- BRCA, for each responder will also be discussed. Trends in disease burden and markers of bone metabolism will also be quantitatively explored including 24% pts who were on treatment for at least one cycle who had ≥25% decreased unfractionated ALP from baseline. Conclusions: Niraparib showed clinical activity with CTC response and decline in ALP levels in mCRPC pts having biallelic BRCA mutations, which further supports its recent breakthrough designation. Clinical trial information: NCT02854436. [Table: see text]

Preliminary results of a prospective assessment of androgen receptor splice variants in mCRPC patients undergoing androgen receptor targeted agents.

246 Background: Different treatment options for metastatic castrate resistant prostate cancer (mCRPC) are currently available, including Androgen Receptor Targeted Agents (ARTA) and Taxane based chemotherapy. However, selection criteria aiming to drive the therapeutic choice in this setting are lacking, and no standardized therapeutic sequence is validated. In our institution, a prospective study testing predictive value of circulating tumor cells (CTC) in patients (pts) receiving a first line ARTA for mCRPC is currently ongoing (PRIMERA). Here, we present preliminary results from the first enrolled cohort. Methods: Pts affected by mCRPC eligible for Androgen Deprivation Therapy (ADT) plus ARTA were prospectively enrolled and underwent baseline determination of androgen-receptor splice variant 7 (AR-V7) and androgen-receptor-full length (ARFL) variants on CTC at baseline (ARTA start). Fisher Exact Test was conducted to explore the correlation between baseline features and CTC detection rate. Results: Overall, 26 pts were enrolled and baseline results are available for 13 pts. CTC were found in 5 (38.5%) pts. No significant difference was reported in terms of CTC detection probability for pts with high vs low burden of disease according to CHARTEED definition (p=0.42), neither for pts with PSA at CRPC diagnosis &lt; or &gt; 10 ng/ml, (p=0.2). However, a PSA &gt; 10 ng/ml at ADT start in metastatic hormone sensitive setting (mHSPC) was significantly related to CTC detection probability (p=0.01). AR-V7 variants were found in 1 out 5 (20%) CTC-positive pts. Conclusions: PSA at ADT start may significantly be related to CTC detection rate. CTC detection could be particularly useful in pts with a high burden of disease at the beginning of systemic therapy. Metastatic disease could remain dormant until development of CRPC status, with consequent release of increased amount of CTC, more likely to be detected in this setting. AR-V7 expression was found in 20% of CTC positive pts, in line with literature data.[Table: see text]

Abstract OT1-02-02: A pilot study to examine the feasibility of measuring CTC and inflammatory biomarker changes resulting from atorvastatin as adjuvant therapy in TNBC and TN-IBC patients with residual disease after neoadjuvant chemotherapy

Abstract Background: Patients who have TNBC or triple negative-IBC (TN-IBC) and do not achieve pathological complete response after neoadjuvant chemotherapy are at significant risk for distant relapse and death from recurrent disease. Apart from capecitabine, there are no proven adjuvant therapies that may improve these poor outcomes of patients with chemo-resistant tumors. Therefore, there is an unmet need for effective systemic therapy for this subset of patients with TNBC. Epidemiological evidence reveals that statin use after diagnosis is associated with improved breast cancer relapse-free survival and decreased mortality. However, direct evidence of in vivo mechanisms explaining this association are lacking. Preclinical studies using statins in breast cancer reveal pathways that statins can inhibit proliferation, stem cell self-renewal and metastatic potential. Trial Design: This is a pilot study designed in 2 phases to assess feasibility of completion while providing a signal of efficacy in biomarker changes. In the first phase, we will follow the initial 30 patients who meet eligibility for atorvastatin treatment for the 2-year treatment window, or until disease recurrence. We will collect blood samples prior to, and during atorvastatin treatment for circulating tumor cells (CTCs), cytokine and inflammatory biomarker analyses. We defined a positive outcome as CTCs remaining non-detected at 6 months when baseline CTC is undetected, or a reduction in the number of CTCs at 6 months compared to baseline. If we observe a positive outcome among the initial 30 patients, then we will open the second phase of this study for an additional 50 patients. Here we will follow both patient cohorts who receive and not receive atorvastatin treatment to collect longitudinal data on biomarkers as a function of the natural history of TNBC to better understand the activity of atorvastatin. Trial Eligibility: Patients with stage II-III TNBC who have residual cancer burden (RCB)-II or RCB-III or stage 3 TN-IBC with any amount of residual disease, and are not taking a statin or any other anti-lipidemic agent are candidates for the study. Patients must have adequate hematologic, organ, and cardiac function and must have recovered from the acute effects of any prior treatments. Baseline lipid profile will be assessed by a cardiologist to determine the patients’ eligibility to take atorvastatin based on current ACC/AHA guideline, and to select between moderate (20mg) or high intensity treatment (40mg). Specific Aims: The primary objective is to determine the proportion of patients with undetectable CTCs at 6 months with and without atorvastatin therapy. Secondary objectives include correlation of baseline lipid profiles/lipid profile changes with 2 year-relapse free survival (RFS), CTC counts and inflammatory biomarkers. Statistical Methods: The total estimated enrollment is 80 patients, including at least 5 treated with adjuvant capecitabine and at least 5 without adjuvant capecitabine. The study overall is powered with the assumption that 48 patients will receive atorvastatin and 32 will not, and this will allow us to estimate the percent of patients with negative CTCs at 6 months with a standard error not larger than 7% and 9%, respectively. All other analyses including inflammatory biomarkers and RFS differences between groups are exploratory and considered hypothesis-generating rather than conclusive. Citation Format: Angela Alexander, Takeo Fujii, Michael C Stauder, Wendy A Woodward, James M Reuben, Yu Shen, Diane Liu, Sangeetha M Reddy, Vicente Valero, Susan C Gilchrist, Bora Lim, Anthony Lucci, Naoto T Ueno, Carlos H Barcenas. A pilot study to examine the feasibility of measuring CTC and inflammatory biomarker changes resulting from atorvastatin as adjuvant therapy in TNBC and TN-IBC patients with residual disease after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-02-02.

Prospective study with circulating tumor cells as potential prognosis biomarker in metastatic colorectal cancer.

203 Background: Colorectal cancer (CRC) is one of the most common cancer worldwide. Around 30% present metastatic disease at diagnosis and 50%–60% of patients develop metastasis. New prognostic markers are needed and circulating tumor cells (CTCs) are a promising tool. Methods: Prospective study conducted by blood collection from 75 patients (pts) with metastatic CRC (mCRC), twice, with 2 months interval, together with image exams for therapeutic response evaluation. CTCs were detected by ISET and identified by immunocytochemistry. Results: The mean age was 57.3 years old (24-81). RAS mutations in primary tumor was found in 38% (19/50) of patients (pts) and left colon topography in 41.3% (31/75). Comparing the baseline CTC level (CTC1) with the level at first follow-up (CTC 2), pts with CTC2 – CTC1 &gt; 5.5 per ml demonstrated poor progression-free survival (PFS) (3.2 months) when compared to CTC 2 – CTC1 ≤ 5.5 (9.1 months) (p= 0.005). The median overall survival (OS) was 24.5 months for pts with CTC 1 &gt; 1.5 per ml and 34.2 months for those with CTC1 ≤ 1.5 per (HR=1.89, 95% CI, 1.01 to 3.52; p= 0.041). Patients with RAS mutation (P= 0.001), primary tumor in the right colon (p= 0.014) and expression of Multidrug Resistance Protein 1 in CTCs (p= 0.044) had worse OS. By multivariable analyses, CTC 1 &gt; 1.5/mL (p= 0.025) was an independent prognostic factor. Conclusions: This prospective study confirmed that counts of CTCs at baseline (CTC1) is an important prognostic marker for monitoring mCRC and correlates with other established prognostic factors. Clinical trial information: NCT02979470.

A lab-on-a-disc platform enables serial monitoring of individual CTCs associated with tumor progression during EGFR-targeted therapy for patients with NSCLC

Rationale: Unlike traditional biopsy, liquid biopsy, which is a largely non-invasive diagnostic and monitoring tool, can be performed more frequently to better track tumors and mutations over time and to validate the efficiency of a cancer treatment. Circulating tumor cells (CTCs) are considered promising liquid biopsy biomarkers; however, their use in clinical settings is limited by high costs and a low throughput of standard platforms for CTC enumeration and analysis. In this study, we used a label-free, high-throughput method for CTC isolation directly from whole blood of patients using a standalone, clinical setting-friendly platform.Methods: A CTC-based liquid biopsy approach was used to examine the efficacy of therapy and emergent drug resistance via longitudinal monitoring of CTC counts, DNA mutations, and single-cell-level gene expression in a prospective cohort of 40 patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer.Results: The change ratio of the CTC counts was associated with tumor response, detected by CT scan, while the baseline CTC counts did not show association with progression-free survival or overall survival. We achieved a 100% concordance rate for the detection of EGFR mutation, including emergence of T790M, between tumor tissue and CTCs. More importantly, our data revealed the importance of the analysis of the epithelial/mesenchymal signature of individual pretreatment CTCs to predict drug responsiveness in patients.Conclusion: The fluid-assisted separation technology disc platform enables serial monitoring of CTC counts, DNA mutations, as well as unbiased molecular characterization of individual CTCs associated with tumor progression during targeted therapy.

The prognostic value of baseline circulating tumor cells in patients with metastatic breast cancer: a meta-analysis

The prognostic value of baseline circulating tumor cells in patients with metastatic breast cancer: a meta-analysis

The Prognostic Value of Circulating Tumor Cells in Asian Neuroendocrine Tumors

Circulating tumor cells (CTC) play important roles in various cancers; however, few studies have assessed their clinical utility in neuroendocrine tumors. This study aimed to prospectively evaluate the prognostic value of CTC counts in Asian patients with neuroendocrine tumors before and during anti-cancer therapy. Patients who were diagnosed with unresectable histological neuroendocrine tumors between September 2011 and September 2017 were enrolled. CTC testing was performed before and during anti-cancer therapy using a negative selection protocol. Chromogranin A levels were also assessed. Univariate and multivariate Cox’s proportional hazard model with forward LR model was performed to investigate the impact of independent factors on overall survival and progression-free survival. Kaplan–Meier method with log-rank tests were used to determine the difference among different clinicopathological signatures and CTC cutoff. The baseline CTC detection rate was 94.3% (33/35). CTC counts were associated with cancer stages (I-III vs. IV, P = 0.015), liver metastasis (P = 0.026), and neuroendocrine tumor grading (P = 0.03). The median progression-free survival and overall survivals were 12.3 and 30.4 months, respectively. In multivariate Cox regression model, neuroendocrine tumors grading and baseline CTC counts were both independent prognostic factors for progression-free survival (PFS, P = 0.005 and 0.015, respectively) and overall survival (OS, P = 0.018 and 0.023, respectively). In Kaplan-Meier analysis, lower baseline chromogranin A levels were associated with longer PFS (P = 0.024). Baseline CTC counts are associated with the clinicopathologic features of neuroendocrine tumors and are an independent prognostic factor for this malignancy.

Circulating tumor cells in lung cancer are prognostic and predictive for worse tumor response in both targeted- and chemotherapy.

It is unknown whether the presence of circulating tumor cells (CTC), a known prognostic factor, influences treatment outcome. We investigated whether baseline CTC in non-small cell lung cancer (NSCLC) patients treated with tyrosine kinase inhibitors (TKI) or chemotherapy was associated with response to therapy. We included consecutive advanced NSCLC patients, stratified by therapy. Before treatment the number of CTC was measured by CellSearch. Tumor response rates, progression free survival (PFS) and overall survival (OS) in patients with and without CTC at baseline were compared. We included 86 patients (34 treated by TKI). Response rates of patients with CTC were lower than in patients without CTC (OR =0.22, P<0.01, adjusted for performance score and smoking status). In both treatment groups, the difference in response rates between patients with and without CTC was similar (TKI response: 25% with CTC versus 73% without CTC, chemotherapy response: 35% versus 51% respectively, interaction P=0.17). CTC was associated with a worse PFS [hazard ratio (HR) =2.0, 95% confidence interval (CI): 1.2-3.2, P=0.01] and OS (HR =1.7, 95% CI: 1.1-2.8, P=0.03) after adjustment for performance score and stage. The association remained significant after adding tumor response to the model (PFS: HR =1.9, 95% CI: 1.0-3.0, P=0.01, OS: HR =1.6, 95% CI: 1.0-2.6, P=0.05). No significant interaction between CTC presence and therapy was observed (P=0.42 for PFS and P=0.83 for OS). Presence of CTC in advanced NSCLC patients is associated with low response rates, shorter PFS and OS, independent of the received therapy.

889P - Circulating tumour cells (CTC) count and prostate-specific antigen (PSA) response measures in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) treated with docetaxel (Doc)

BackgroundClinically meaningful measures of response are needed in mCRPC. Post-treatment CTC decline have shown to be superior to PSA response in determining outcome in pts treated with AR signalling inhibitors. We compared the performance of CTC and PSA measures of response in mCRPC Doc-treated pts. MethodsBaseline and post-treatment (6 to 9 weeks) CTC of mCRPC pts treated with Doc at first or second-line in a prospective study were determined with CellSearchTM platform. CTC response was defined: 30% decline from baseline (CTC30%), conversion (≥5 to<5; CTCConv) or decline to 0 CTC in pts with >0 baseline CTC (CTC0). PSA response was determined at 12w as 30% (PSA30) or 50% decline (PSA50) from baseline. Cox-regression model were used to evaluate the association of baseline CTC (BLCTC), CTC response and PSA response measures with overall survival (OS), progression-free survival (PFS) or time to PSA progression (TTPP). C-index were used to evaluate the performance of each of the Cox regression model. Results80 pts had evaluable BLCTC, 52 had evaluable post-treatment CTC count. Of 80 eligible pts, 53 (66.3%) received Doc at first-line. Median OS was 19 m (95%CI:16.4-21.8); median BLCTC was 7. BLCTC were associated with bone mts, higher PSA, ALP and LDH, and lower albumin levels. BLCTC was associated with OS (HR: 3.5; p<0.001), PFS (HR: 1.98; p=0.001) and TTPP (HR: 1.8; p=0.001). CTC (CTC30%, CTCConv, CTC0) but not PSA (PSA30, PSA50) response measures were significantly associated with OS. C-index values were higher for CTC resp endpoints (Table). 24 pts had discordant PSA30 and CTC30% response; longer OS (18.4 vs 8.4m; p=0.188) was observed in pts with CTC30% resp, without PSA30 resp.Table889PTableN (%)HR (95%CI); p-valueC-indexCTC Conv27 (51.9)0.33 (0.18-0.60); p<0.0010.665CTC08 (15.4)0.26 (0.10-0.67); p=0.0050.602CTC30%34 (65.4)0.33 (0.18-0.61); p<0.0010.644PSA3032 (61.5)0.72 (0.40-1.30); p=0.2710.563PSA5022 (42.3)0.68 (0.38-1.20); p=0.1830.595 ConclusionsBaseline CTC were associated with OS, PFS and TTPP. CTC response measures were significantly associated with outcome, and showed a greater performance than PSA response measures in mCRPC Doc-treated pts. Legal entity responsible for the studySpanish National Cancer Research Center (CNIO) and The Institute of Cancer Research (ICR). FundingHas not received any funding. DisclosureR. Lozano Mejorada: Honoraria (self): Roche, Janssen-Cilag, Bayer; Research grant / Funding (institution): Bayer, Janssen-Cilag; Travel / Accommodation / Expenses: Roche, Janssen-Cilag, Astellas Pharma. D. Lorente: Honoraria (self): Janssen-Cilag, Bayer, Astellas Pharma, Sanofi; Advisory / Consultancy: Janssen-Cilag, Bayer, Sanofi; Travel / Accommodation / Expenses: Sanofi, Astellas, Janssen-Cilag, Celgene. E. Castro: Honoraria (self): Astellas Pharma, Janssen-Cilag, AstraZeneca, Bayer, Pfizer; Advisory / Consultancy: Bayer, Janssen-Cilag, AstraZeneca, Clovis Oncology; Research grant / Funding (institution): Janssen-Cilag, AstraZeneca, Bayer; Travel / Accommodation / Expenses: Bayer, Janssen-Cilag, Roche, Astellas Pharma. N. Romero Laorden: Honoraria (self): MSD, Sanofi-Aventis, Astellas, Janssen-Cilag; Travel / Accommodation / Expenses: Bayer, Janssen-Cilag, Roche, PharmaMar; Research grant / Funding (institution): Bayer, Astellas, Janssen-Cilag, Sanofi-Aventis. E. Almagro Casado: Honoraria (self): MSD; Travel / Accommodation / Expenses: BMS. M. Saez: Honoraria (self): Bristol-Myers Squibb, Pfizer, Novartis, Bayer, Janssen-Cilag, Sanofi-Aventis, Astellas Pharma, Ipsen, EUSA Pharma; Advisory / Consultancy: Bristol-Myers Squibb, Pfizer, Novartis, Bayer, Janssen-Cilag, Sanofi-Aventis, Astellas Pharma, Ipsen, EUSA Pharma; Travel / Accommodation / Expenses: Bristol-Myers Squibb, Pfizer, Novartis, Bayer, Janssen-Cilag, Sanofi-Aventis, Astellas Pharma, Ipsen, EUSA Pharma. D. Olmos Hidalgo: Honoraria (self): Janssen-Cilag, Bayer, Sanofi; Advisory / Consultancy: Bayer, Janssen-Cilag, AstraZeneca, Clovis Oncology; Research grant / Funding (institution): Bayer, Janssen-Cilag, AstraZeneca, Roche/Genentech, Medications/Pfizer, Astellas, Tokai, MSD, GSK; Travel / Accommodation / Expenses: Bayer, Janssen-Cilag, Ipsen. All other authors have declared no conflicts of interest.

320P - Untargeted assessment of tumour fractions in plasma for monitoring and prognostication from metastatic breast cancer patients undergoing systemic treatment

BackgroundThe aim of this study was to assess the prognostic and predictive value of an untargeted assessment of tumor fractions in the plasma of metastatic breast cancer patients and to compare circulating tumor DNA (ctDNA) with circulating tumor cells (CTC) and conventional tumor markers. MethodsPatients and methods: 29 patients with metastatic breast cancer were included in this single-institution observational cohort study. Blood samples were obtained at first diagnosis of metastases, during several lines of treatment, and/or at every further moment of progression/development of new metastases. We assessed tumor fractions in plasma using an untargeted mFAST-SeqS method. CTCs were captured using a sized-based microfilter and identified as nucleated, cytokeratin positive/CD45 negative cells. Resulting ctDNA z-scores were compared to tumor fractions established with the recently published ichorCNA algorithm and associated with the clinical outcome. ResultsWe observed a close correlation between mFAST-SeqS z-scores and ichorCNA ctDNA quantifications. Patients with mFAST-SeqS z-scores above three (34.5%) showed significantly worse overall (p=0.014) and progression-free survival (p=0.018) compared to patients with lower values. Elevated z-score values were clearly associated with radiological proven progression. In contrast, baseline CTC count, CEA, and CA15-5 had no prognostic impact on the outcome of patients in the analyzed cohort. ConclusionsThis proof of principle study demonstrates the prognostic impact of ctDNA levels detected with mFAST-SeqS as a very fast and cost-effective means to assess the ctDNA fraction without prior knowledge of the genetic landscape of the tumor. Furthermore, mFAST-SeqS-based ctDNA levels provided an early means of measuring treatment response. Legal entity responsible for the studyThe authors. FundingKrebshilfe Steiermark. DisclosureAll authors have declared no conflicts of interest.

Detection and prognostic relevance of circulating tumour cells (CTCs) in Asian breast cancers using a label-free microfluidic platform.

ObjectivesWe aimed to study the prevalence of CTCs in breast cancer (BC) patients undergoing neoadjuvant or palliative therapy with a label-free microfluidic platform (ClearCell FX), and its prognostic relevance in metastatic BC (mBC).Materials and methodsPeripheral blood samples were collected from 108 BC patients before starting a new line of treatment (“baseline”), majority of whom had mBC (76/108; 70.4%). CTCs were retrieved by dean flow fractionation that enriched for larger cells, and enumerated using immunofluorescence-based staining. Progression-free survival (PFS) in mBC patients was analysed using Kaplan-Meier method; cox proportional hazard models were used for univariable and multivariable analyses.ResultsThe detection rate of CTCs before starting a new line of treatment was 75.9% (n = 108; median: 8 CTCs/7.5 ml blood) at a cut off of ≥2 CTCs. PFS was inferior for mBC patients with baseline CTC count ≥5 CTCs/7.5 ml blood vs. those with < 5 CTCs/7.5 ml blood (median PFS: 4.3 vs. 7.0 months; p-value: 0.037). The prognostic relevance of CTCs was most significant in patients with HER2- mBC (median PFS: 4.1 vs. 8.3 months; p-value: 0.032), luminal (HR+HER2-) subtype (median PFS: 4.2 vs. 8.3 months; p-value: 0.048), and patients who had one or more prior treatments (median PFS: 4.2 vs. 7.0 months; p-value: 0.02). On multivariable analysis, baseline CTC level (hazard ratio (HR): 1.84, p-value: 0.02) and pre-treatment status (HR: 1.87, p-value: 0.05) were independent predictors of PFS.ConclusionsThis work demonstrates the prognostic significance of CTCs in mBC detected using a label-free size-based enrichment platform.

Pre-Treatment Circulating Tumor Cell Levels Correlate with Regional and Distant Failure Rates Following Stereotactic Body Radiation Therapy for Early Stage Non-Small Cell Lung Cancer

Stereotactic body radiation therapy (SBRT) has become the standard of care for patients with medically inoperable early stage non-small cell lung cancer (NSCLC) due to good local control rates and minimal morbidity. However, of patients treated with SBRT, 10-15% patients fail regionally and 25% fail distantly. Our hypothesis underlying this prospective trial was that a high burden of circulating tumor cells (CTCs) prior to treatment is a useful prognostic marker for increased risk of recurrence following SBRT. 92 subjects with stage I NSCLC treated with SBRT were prospectively enrolled on an IRB-approved protocol. CTCs were enumerated by an assay utilizing a green fluorescent protein (GFP)-expressing adenoviral probe that detects the elevated telomerase activity in cancer cells. CTC “positivity” was defined as 1.3 GFP-positive cells per mL of peripheral blood samples. Pre-treatment samples were collected at the time of treatment consent for SBRT or at simulation. RT was delivered to a median dose of 50Gy (range, 40-60 Gy) in five fractions. Patient characteristics: female (58%), Caucasian (80%), and current (20%) or former (75%) smokers; median age was 71 years. Subjects had T1a (64%), T1b (23%), or T2a (13%) NSCLC with a median tumor size of 1.7 cm (range, 0.5-5.0 cm). Kaplan-Meier survival analysis and Cox multivariate regression analysis explored the relative effect of covariates on recurrence and survival outcomes, controlling for history of previous NSCLC, tumor size, and pre-treatment PET scan SUVmax. Receiver operating characteristic curves were generated for a series of baseline CTC values between 2 and 7 to identify if there were a threshold value prognostic of disease recurrence. With a median follow-up of 24 months (range, 2-62 months), the 2-year local, regional and distant control rates were 90.0%, 86.4%, and 86.5%, respectively. 38 of 92 subjects (40%) had a positive CTC test prior to treatment. Overall, a positive CTC test when compared to a negative test was not associated with local, nodal, or distant recurrence. A pre-SBRT cutoff of ≥5 CTCs/mL demonstrated the maximal area under the cure in predicting any event of recurrence (AUC=0.64, specificity=90.4%), therein defining favorable (n=78) and unfavorable (n=14) prognostic groups by baseline CTC. Increased risk of nodal and distant failure was observed in the unfavorable versus favorable cohorts, with 2-year freedom from nodal and distant failure of 83.9% and 75.7% versus 86.7% (HR 3.92, p=0.04) and 89.2%, (HR 4.29, p=0.03). Higher pre-treatment CTC counts appears to be predictive of increased risks of regional and distant recurrences following SBRT for early stage NSCLC, thus potentially identifying the subset of patients at highest risk of regional and distant recurrences who could benefit most from intensified or adjuvant systemic therapy.

Improved Stratification for Risk of Early Metastases by Baseline Circulating Tumor Cell Counts for Locally Advanced Rectal Cancer in Neoadjuvant Setting: an Exploratory Analysis from a Phase III trial

Improved Stratification for Risk of Early Metastases by Baseline Circulating Tumor Cell Counts for Locally Advanced Rectal Cancer in Neoadjuvant Setting: an Exploratory Analysis from a Phase III trial