Cell-free DNA concentration as a biomarker of response and recurrence in HER2-negative breast cancer receiving neoadjuvant chemotherapy

PURPOSE

We previously demonstrated the clinical significance of circulating tumor DNA (ctDNA) in patients with HER2-negative breast cancer receiving neoadjuvant chemotherapy (NAC). Here, we compared its predictive and prognostic value with cell-free DNA (cfDNA) concentration measured in the same samples from the same patients.

EXPERIMENTAL DESIGN

145 hormone receptor (HR)-positive/HER2-negative and 138 triple-negative breast cancer (TNBC) patients with ctDNA data from a previous study were included in the analysis. Associations of serial cfDNA concentration with residual cancer burden (RCB) and distant recurrence-free survival (DRFS) were examined.

RESULTS

In TNBC, we observed a modest negative correlation between cfDNA concentration 3 weeks after treatment initiation and RCB, but none of the other timepoints showed significant correlation. In contrast, ctDNA was significantly positively correlated with RCB at all timepoints (all R>0.3 and p<0.05). In the HR-positive/HER2-negative group, cfDNA concentration did not associate with response to NAC, but survival analysis showed that high cfDNA-shedders at pretreatment had a significantly worse DRFS than low shedders (hazard ratio 2.12, p=0.037). In TNBC, the difference in survival between high vs. low cfDNA-shedders at all timepoints was not statistically significant. In contrast, as previously reported, ctDNA at all timepoints was significantly correlated with DRFS in both subtypes.

CONCLUSIONS

In TNBC, cfDNA concentrations during therapy were not strongly correlated with response or prognosis. In the HR-positive/HER2-negative group, pretreatment cfDNA concentration was prognostic for DRFS. Overall, the predictive and prognostic value of cfDNA concentration was more limited than that of ctDNA.

Clinical significance and biology of circulating tumor DNA in high-risk early-stage HER2-negative breast cancer receiving neoadjuvant chemotherapy

Circulating tumor DNA (ctDNA) analysis may improve early-stage breast cancer treatment via non-invasive tumor burden assessment. To investigate subtype-specific differences in the clinical significance and biology of ctDNA shedding, we perform serial personalized ctDNA analysis in hormone receptor (HR)-positive/HER2-negative breast cancer and triple-negative breast cancer (TNBC) patients receiving neoadjuvant chemotherapy (NAC) in the I-SPY2 trial. ctDNA positivity rates before, during, and after NAC are higher in TNBC than in HR-positive/HER2-negative breast cancer patients. Early clearance of ctDNA 3 weeks after treatment initiation predicts a favorable response to NAC in TNBC only. Whereas ctDNA positivity associates with reduced distant recurrence-free survival in both subtypes. Conversely, ctDNA negativity after NAC correlates with improved outcomes, even in patients with extensive residual cancer. Pretreatment tumor mRNA profiling reveals associations between ctDNA shedding and cell cycle and immune-associated signaling. On the basis of these findings, the I-SPY2 trial will prospectively test ctDNA for utility in redirecting therapy to improve response and prognosis.

Outcomes and clinicopathologic characteristics associated with disseminated tumor cells in bone marrow after neoadjuvant chemotherapy in high-risk early stage breast cancer: the I-SPY SURMOUNT study

PURPOSE

Disseminated tumor cells (DTCs) expressing epithelial markers in the bone marrow are associated with recurrence and death, but little is known about risk factors predicting their occurrence. We detected EPCAM+/CD45- cells in bone marrow from early stage breast cancer patients after neoadjuvant chemotherapy (NAC) in the I-SPY 2 Trial and examined clinicopathologic factors and outcomes.

METHODS

Patients who signed consent for SURMOUNT, a sub-study of the I-SPY 2 Trial (NCT01042379), had bone marrow collected after NAC at the time of surgery. EPCAM+CD45- cells in 4 mLs of bone marrow aspirate were enumerated using immunomagnetic enrichment/flow cytometry (IE/FC). Patients with > 4.16 EPCAM+CD45- cells per mL of bone marrow were classified as DTC-positive. Tumor response was assessed using the residual cancer burden (RCB), a standardized approach to quantitate the extent of residual invasive cancer present in the breast and the axillary lymph nodes after NAC. Association of DTC-positivity with clinicopathologic variables and survival was examined.

RESULTS

A total of 73 patients were enrolled, 51 of whom had successful EPCAM+CD45- cell enumeration. Twenty-four of 51 (47.1%) were DTC-positive. The DTC-positivity rate was similar across receptor subtypes, but DTC-positive patients were significantly younger (p = 0.0239) and had larger pretreatment tumors compared to DTC-negative patients (p = 0.0319). Twenty of 51 (39.2%) achieved a pathologic complete response (pCR). While DTC-positivity was not associated with achieving pCR, it was significantly associated with higher RCB class (RCB-II/III, 62.5% vs. RCB-0/I; 33.3%; Chi-squared p = 0.0373). No significant correlation was observed between DTC-positivity and distant recurrence-free survival (p = 0.38, median follow-up = 3.2 years).

CONCLUSION

DTC-positivity at surgery after NAC was higher in younger patients, those with larger tumors, and those with residual disease at surgery.

Abstract LB111: Comparison of the predictive and prognostic significance of circulating tumor DNA in patients with high risk HER2-negative breast cancer receiving neoadjuvant chemotherapy

Background: We compared the predictive and prognostic value of ctDNA dynamics in high-risk hormone receptor-positive/HER2-negative (HR+/HER2-) and triple negative breast cancer (TNBC) receiving neoadjuvant chemotherapy (NAC) enrolled in the I-SPY 2 trial (NCT01042379). To our knowledge, this is the largest ctDNA study in breast cancer in the neoadjuvant setting.

Methods: Blood samples were collected at pre-treatment (T0), during treatment (T1 at 3 weeks, and T2 at 12 weeks) and after NAC (T3 at 24 weeks) from 106 HR+/HER2- and 97 TNBC patients. Plasma samples (n=734) were analyzed using a personalized and tumor-informed mPCR NGS-based ctDNA test (SignateraTM). Patients, all high risk for recurrence by MammaPrint, received paclitaxel-based treatment +/- experimental therapy followed by anthracycline. The median follow-up was 3.0 years (0.5 to 6.5). The predictive and prognostic value of ctDNA dynamics and status at different timepoints were examined. Our analysis is exploratory and does not adjust for other biomarkers.

Results: Pretreatment ctDNA positivity (Fisher p&lt;0.0001) and levels (mean tumor molecules/mL, MTM/mL, t test p=0.0062) were significantly higher in TNBC (90.7%, 14.7 MTM/mL) than in high risk HR+/HER2- (66.0%, 5.5 MTM/mL). Early and late ctDNA clearance during treatment (3 and 12 weeks of NAC) was predictive of pathologic complete response (pCR) and residual cancer burden (RCB), class 0-III, in TNBC but not HR+/HER2- (Table). In both subtypes: (1) ctDNA was a significant negative prognostic factor for distant recurrence-free survival (DRFS) at all timepoints (p&lt;0.05) except at pretreatment; (2) all patients who achieved pCR were ctDNA-negative after NAC; (3) among non-responding patients, ctDNA-negativity after NAC was associated with improved DRFS (Table).

Conclusions: The predictive value of ctDNA for prediction of pCR and RCB differed between subtypes (HR+/HER2- vs. TNBC), while similar prognostic value was observed. In TNBC, early clearance of ctDNA at 3 weeks was a significant predictor of favorable response to NAC. Compared to patients who were ctDNA-positive after NAC, ctDNA-negative status in both subtypes was associated with improved DRFS even in patients with residual cancer (no pCR or RCB-II/III). These findings could inform on the design of future studies that seek to demonstrate the utility of ctDNA in the curative setting.

Predictive and prognostic significance of ctDNA in early breast cancer in the neoadjuvant setting HR+HER2- (n=106) TNBC (n=97) Predictive value for prediction of pCR and RCB Fisher p-value Fisher p-value Early ctDNA clearance (between T0 and T1) and pCR 0.4521 &lt;0.0001 Late ctDNA clearance (between T0 and T2) and pCR 0.8071 0.0004 Early ctDNA clearance (between T0 and T1) and RCB (0-III) 0.1360 &lt;0.0001 Late ctDNA clearance (between T0 and T2) and RCB (0-III) 0.4869 0.0004 Early ctDNA clearance at T1 and pCR rates pCR rate pCR rate ctDNA clearance (ctDNA+ at T0/ctDNA- at T1) 21% 67% Late ctDNA clearance (betweeNo early clearance (ctDNA+ at T0/ctDNA+ at T1) 13% 14% Prognostic value for prediction of DRFS Log rank p-value Log rank p-value ctDNA at T3 and pCR vs no PCR 0.0002 &lt;0.0001 ctDNA at T3 and RCB (0-I vs II-III) 0.0110 &lt;0.0001 Timepoints: T0 - pretreatment; T1 - three weeks after treatment initiation; T2 - at 12 weeks, between paclitaxel-based and anthracycline regimens; T3- after neoadjuvant chemotherapy prior to surgery

Citation Format: Mark Jesus Mendoza Magbanua, Lamorna Brown Swigart, Derrick Renner, Svetlana Shchegrova, Gillian L. Hirst, Christina Yau, Denise M. Wolf, Hsin-Ta Wu, Ekaterina Kalashnikova, Amy L. Delson, A. Jo Chien, Debu Tripathy, Smita Asare, Raheleh Salari, Angel Rodriguez, Bernhard Zimmermann, Himanshu Sethi, Alexey Aleshin, Paul Billings, Rita Nanda, Hope S. Rugo, Laura J. Esserman, Minetta C. Liu, Angela DeMichele, Laura van 't Veer. Comparison of the predictive and prognostic significance of circulating tumor DNA in patients with high risk HER2-negative breast cancer receiving neoadjuvant chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB111.

Abstract P2-01-03: Elucidating the biology of circulating tumor DNA (ctDNA) shedding across receptor subtypes in high-risk early-stage breast cancer

Background: Identifying mechanisms that govern the shedding of ctDNA in blood could inform the use of liquid biopsy in individual patients. Previous studies in the I-SPY2 neoadjuvant trial involving high-risk breast cancer showed that the detection of ctDNA before treatment was associated with aggressive clinical characteristics and residual ctDNA after treatment was associated with poor outcomes. Moreover, ctDNA positivity rates significantly varied across breast cancer subtypes suggesting that ctDNA shedding may in part be driven by subtype-specific etiology. We performed genome-wide transcriptomic analysis to identify genes and biological processes associated with increased ctDNA shedding within and across receptor subtypes. Methods: Our study involved 227 patients in I-SPY2 with tumor gene expression and ctDNA data at pretreatment. All patients were at high risk for recurrence (MammaPrint high). Each subtype: HR+HER2- (n=109), HER2+ (n=19), and triple negative breast cancer (TNBC, n=99) was evaluated independently. We performed differential expression (DE) analysis on the global transcriptome (m=19,134 genes) and curated gene signature (cGS, m=31 signatures developed in I-SPY2) data between ctDNA+ and ctDNA- patients at baseline. Gene-set enrichment analysis (GSEA) was also performed across hallmark (H, m=50), canonical pathway (CP, m=5,501), gene ontology (GO, m=9,996) and immunologic (IM, m=4,872) gene sets. Features were associated with ctDNA shedding if Benjamini-Hochberg adjusted p &lt; 0.05. For subtypes with smaller sample size and unbalanced groups, we also report features with nominally significant p &lt; 0.05. Results: ctDNA positivity rate was significantly higher in TNBC (91%) than in HR+HER2- and HER2+ (65% and 74% respectively, Fisher p &lt;0.001). The HR+HER2- subtype had the most significant hits for DE analysis between ctDNA+ and ctDNA- patients, with 0.2% of genes and 3.2% of cGS. No genes or cGS were differentially expressed in TNBC and HER2+, likely due to imbalance or small size of these groups. For GSEA, we observed the most significant number of enrichments in HR+HER2- subtype, with 58%, 21.8%, 4.4% and 40.3% of H, CP, GO, and IM gene sets enriched, respectively. In the HER2+ subtype, 40% H, 15.7% CP and 36.4% IM gene sets were significantly enriched, while no gene sets were enriched in TNBC. To identify common mechanistic themes across subtypes, we also considered nominally significant features in DE and GSEA. Processes associated with infection and innate immune responses were enriched in ctDNA+ patients, while adaptive immune response and antigen presentation—e.g., T-cell, TCR and MHC II protein complex, and downregulation of MYC targets were enriched in ctDNA- patients. HR+HER2- and HER2+ subtypes shared the most common modulated features with 134 genes and 2,165 gene sets, including up-regulation of cell cycle and proliferation in ctDNA+ patients, as well as up- or down-regulation of specific immunologic and metabolic processes. In contrast, TNBC gene set enrichment was associated with more distinct biologic processes, sharing common enrichment of 113 and 27 gene sets with HR+HER2- and HER2+ subtype, respectively. Conclusions: Findings from our exploratory analysis suggest a key role of immune response pathways in the control of ctDNA release. Additionally, tumor cell proliferation was associated with increased shedding in HR+HER2- and HER2+ subtypes, while down regulation of MYC targets was associated with ctDNA- patients across all subtypes. These suggest an important role of cell cycle in ctDNA shedding. Overall, our analysis revealed common and unique mechanisms potentially associated with ctDNA shedding across and within subtypes. However, due to the unbalanced groups and limited sample sizes, validation in a larger cohort is warranted.

Citation Format: Rosalyn W. Sayaman, Denise M. Wolf, Christina Yau, Lamorna Brown Swigart, Gillian L. Hirst, Laura Sit, Nicholas O'Grady, Amy L. Delson, I-SPY2 Investigators, Laura Esserman, Laura J. van 't Veer, Mark Jesus M. Magbanua. Elucidating the biology of circulating tumor DNA (ctDNA) shedding across receptor subtypes in high-risk early-stage breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-01-03.

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

BACKGROUND

We examined the prognostic significance of circulating tumor cell (CTC) dynamics during treatment in metastatic breast cancer (MBC) patients receiving first-line chemotherapy.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Circulating tumor DNA and magnetic resonance imaging to predict neoadjuvant chemotherapy response and recurrence risk

We investigated whether serial measurements of circulating tumor DNA (ctDNA) and functional tumor volume (FTV) by magnetic resonance imaging (MRI) can be combined to improve prediction of pathologic complete response (pCR) and estimation of recurrence risk in early breast cancer patients treated with neoadjuvant chemotherapy (NAC). We examined correlations between ctDNA and FTV, evaluated the additive value of ctDNA to FTV-based predictors of pCR using area under the curve (AUC) analysis, and analyzed the impact of FTV and ctDNA on distant recurrence-free survival (DRFS) using Cox regressions. The levels of ctDNA (mean tumor molecules/mL plasma) were significantly correlated with FTV at all time points (p < 0.05). Median FTV in ctDNA-positive patients was significantly higher compared to those who were ctDNA-negative (p < 0.05). FTV and ctDNA trajectories in individual patients showed a general decrease during NAC. Exploratory analysis showed that adding ctDNA information early during treatment to FTV-based predictors resulted in numerical but not statistically significant improvements in performance for pCR prediction (e.g., AUC 0.59 vs. 0.69, p = 0.25). In contrast, ctDNA-positivity after NAC provided significant additive value to FTV in identifying patients with increased risk of metastatic recurrence and death (p = 0.004). In this pilot study, we demonstrate that ctDNA and FTV were correlated measures of tumor burden. Our preliminary findings based on a limited cohort suggest that ctDNA at surgery improves FTV as a predictor of metastatic recurrence and death. Validation in larger studies is warranted.

Abstract A50: Circulating tumor DNA (ctDNA) and magnetic resonance imaging (MRI) for monitoring and predicting response to neoadjuvant therapy (NAT) in high-risk early breast cancer patients in the I-SPY 2 TRIAL

Background: MRI measurements (Li et al., Magn Reson Imaging 2019; Hylton et al., Radiology 2016) and ctDNA (Magbanua et al., SABCS 2018) have both been independently shown to associate with response to NAT. We performed a retrospective study to examine correlation between ctDNA and MRI and to investigate whether information from these two measurements can be combined to improve early prediction of response.

Methods: We analyzed serial ctDNA and MRI data from 84 high-risk (stage II/III) breast cancer patients collected at baseline (T0), 3 weeks after initiation of paclitaxel-based NAT (T1), between paclitaxel and anthracycline regimens (T2), and after NAT prior to surgery (T3). The response variable was pathologic complete response (pCR), defined as the absence of invasive tumor in the breast and lymph nodes after NAT. We examined correlations between MR functional tumor volume (FTV) and ctDNA using Spearman's rho (r). Mean FTV between ctDNA+/- groups were compared using t-test. Monte Carlo simulation was used to assess correlation between FTV and ctDNA trajectories in individual patients. We investigated the impact of adding ctDNA information to MR FTV-based predictors using receiver operating characteristic curves to calculate area under the curve (AUC), logistic regressions, and decision trees using recursive partitioning.

Results: The mean levels of ctDNA (mutant molecules/mL plasma) were significantly correlated with FTV at all timepoints [T0 (r=0.49), T1 (r=0.42), T2 (r=0.42), T3 (r=0.43), all p&lt;0.05]. The mean FTV in patients who had detectable ctDNA was significantly higher compared to those who were negative (all timepoints, all p&lt;0.05). FTV and ctDNA trajectories in individual patients over the course of therapy were correlated (empirical 1-sided p=0.046). Adding continuous ctDNA information (mutant molecules/mL plasma) to FTV at T1 improved AUC in the pCR-prediction model, but the increase was not statistically significant (FTV: 0.59, FTV+ctDNA: 0.69, p=0.25). No improvements in AUCs were observed at other timepoints. Treated as a dichotomous variable, ctDNA positivity at T1 trended toward association with non-pCR in logistic regression models at T2 and T3 with MR-based prediction scores as a covariate (0.05).

Citation Format: Mark Jesus M. Magbanua, Laura H. Hendrix, Terry Hyslop, William T. Barry, Eric P. Winer, Clifford Hudis, Deborah Toppmeyer, Lisa Anne Carey, Ann H. Partridge, Jean-Yves Pierga, Tanja Fehm, José Vidal-Martínez, Dimitrios Mavroudis, Jose A. Garcia-Saenz, Justin Stebbing, Paola Gazzaniga, Luis Manso, Rita Zamarchi, María Luisa Antelo, Leticia De Mattos-Arruda, Daniele Generali, Carlos Caldas, Elisabetta Munzone, Luc Dirix, Amy L. Delson, Harold Burstein, Misbah Qadir, Cynthia Ma, Janet H. Scott, François-Clément Bidard, John W. Park, Hope S. Rugo. Circulating tumor DNA (ctDNA) and magnetic resonance imaging (MRI) for monitoring and predicting response to neoadjuvant therapy (NAT) in high-risk early breast cancer patients in the I-SPY 2 TRIAL [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A50.

Abstract P6-10-02: Assessing biomarkers to inform treatment de-escalation: Mid-treatment biopsy cellularity predicts pCR in the I-SPY 2 Trial

Background: The I-SPY 2 TRIAL enrolls women with locally advanced, molecular high-risk breast cancer. An integrated Residual Cancer Burden (iRCB), based on MRI volume change through treatment, is used to predict pathologic complete response (pCR) in the randomization/evaluation Bayesian engine. With the goal of effective de-escalation of treatment for patients exhibiting an early response, biomarkers are being assessed for their ability to predict pCR, alone or with MR data, during treatment. Here, we present the results of a pilot study to examine if invasive tumor cellularity in mid-treatment tissue core biopsies predicts pCR in a 40-patient cohort of I-SPY 2 patients. Other pathologic variables evaluated include Ki67, tumoral histologic features, and stromal tumor-infiltrating lymphocytes (sTILs).

Methods: I-SPY 2 TRIAL pathologists (N=4) were provided images of H&E-stained and Ki67 IHC- labelled (DAKO/Agilent, clone MIB-1) core biopsy sections from 40 patients at the inter-regimen time point, ~12-weeks into treatment. Of the 40 patients, 35 had 4 cores, 3 had 3 cores, and 2 had 2 cores assessed. In total, images from 153 cores were evaluated. For each core, pathologists were asked to score the % area occupied by tumor bed (treatment changes and/or residual cancer), % of viable invasive tumor (0-100%) within tumor bed (with Nottingham grading, % Ki67 labelled, and % sTILs, using standardized guidelines). As decided by the pathologist group, only cores with identified tumor bed were included in the initial analysis. Concordance between pathologists was assessed for all scored criteria, using % agreement for dichotomous variables, and Pearson correlation (r)/standard deviation (sd) for continuous variables. The maximum and average cellularity recorded over all cores/patient, averaged over all pathologists, were analyzed for association with pCR using t- tests (significance threshold: p&lt;0.05). Fisher’s Exact test was used for dichotomous variables, and Pearson’s correlation for association of continuous variables with the residual cancer burden (RCB) index.

Results: Pathologist were in general agreement about the presence or absence of tumor bed, with greater than 82% agreement between any two (83-96%), and an overall agreement of 77%. For scoring the % of the tumor bed involved by invasive cancer, correlations between pairs of pathologists ranged from 0.79-0.95 (mean(r)=0.87, sd=5%), and agreement on a binary presence/absence of invasive cancer was 78%. Both the mean (t-test: p=7.59E-05) and maximum (t-test: p=0.0012) %invasive tumor at 12 weeks, scored as an average over all pathologists, were significantly higher in patients who did not achieve pCR than in responders. We also treated %invasive cellularity as a dichotomous variable (present/absent). 90% (9/10) of patients scored by all pathologists as 0% invasive tumor cells (absent) achieved a pCR, vs only 20% (6/30) of patients scored as &gt;0% invasive cellularity by one or more pathologists (present) (OR=32, Fisher p=0.0005); yielding a positive predictive value for pCR of 0.9. Ki67 and sTILS at 12 weeks were fairly concordant across pathologists ((r,sd)=(0.92, 8.45%) and (0.82,5.5%), respectively), but did not associate with response (p&gt;0.05 for pCR, RCB01, or RCB index). Tumor histologic grade at 12 weeks, assessed in 29/30 patients with non-zero cellularity, trended toward association (Fisher p=0.078): 44% (4/9) with Grade 3 went on to have a pCR, vs. 15% (2/13) with Grade 2 and 0 with Grade 1. These data demonstrate the utility of invasive tumor cellularity as a predictor of pCR in a clinical setting.

Conclusion: In this pilot study we demonstrate that the absence of invasive cancer cells within identified tumor bed in mid-treatment core biopsy samples is highly predictive of pCR.

Citation Format: Sara J Venters, Denise M Wolf, Lamorna Brown-Swigart, Christina Yau, Amy L Delson, Bev Parker, Ron Balassanian, Jodi Carter, Yunn-Yi Chen, Kimberly Cole, Laila Khazai, Molly Klein, Dina Kokh, Gregor Krings, Sunati Sahoo, Jane Wei, I-SPY 2 TRIAL Consortium, Laura J Esserman, Laura J van't Veer, W Fraser Symmans. Assessing biomarkers to inform treatment de-escalation: Mid-treatment biopsy cellularity predicts pCR in the I-SPY 2 Trial [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 P6-10-02.

Synchronous Detection of Circulating Tumor Cells in Blood and Disseminated Tumor Cells in Bone Marrow Predicts Adverse Outcome in Early Breast Cancer

PURPOSE

We examined the prognostic impact of circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) detected at the time of surgery in 742 untreated patients with early breast cancer.

EXPERIMENTAL DESIGN

DTCs in bone marrow were enumerated using the EPCAM-based immunomagnetic enrichment and flow cytometry (IE/FC) assay. CTCs in blood were enumerated either by IE/FC or CellSearch. Median follow-up was 7.1 years for distant recurrence-free survival (DRFS) and 9.1 years for breast cancer-specific survival (BCSS) and overall survival (OS). Cox regressions were used to estimate hazard ratios for DRFS, BCSS, and OS in all patients, as well as in hormone receptor-positive (HR-positive, 87%) and HR-negative (13%) subsets.

RESULTS

In multivariate models, CTC positivity by IE/FC was significantly associated with reduced BCSS in both all (n = 288; P = 0.0138) and HR-positive patients (n = 249; P = 0.0454). CTC positivity by CellSearch was significantly associated with reduced DRFS in both all (n = 380; P = 0.0067) and HR-positive patients (n = 328; P = 0.0002). DTC status, by itself, was not prognostic; however, when combined with CTC status by IE/FC (n = 273), double positivity (CTC+/DTC+, 8%) was significantly associated with reduced DRFS (P = 0.0270), BCSS (P = 0.0205), and OS (P = 0.0168). In HR-positive patients, double positivity (9% of 235) was significantly associated with reduced DRFS (P = 0.0285), BCSS (P = 0.0357), and OS (P = 0.0092).

CONCLUSIONS

Detection of CTCs in patients with HR-positive early breast cancer was an independent prognostic factor for DRFS (using CellSearch) and BCSS (using IE/FC). Simultaneous detection of DTCs provided additional prognostic power for outcome, including OS.

Abstract P3-01-02: Detection of circulating tumor cells (CTC) in blood and disseminated tumor cells (DTC) in bone marrow at surgery identifies breast cancer patients (pts) with long-term risk of distant recurrence and breast cancer-specific death

We examined the prognostic impact of CTCs and DTCs detected at the time of definitive surgery in pts diagnosed with early breast cancer (EBC).

Methods: Blood and bone marrow samples from 742 treatment-naïve EBC pts, not eligible for neoadjuvant therapy, were collected immediately prior to surgery. 87% were hormone receptor (HR)-positive, and 71% were node-negative. DTCs (n=584) were enumerated using an EPCAM-based method involving immunomagnetic enrichment and flow cytometry (IE/FC). CTCs were enumerated either by IE/FC (n=288) or CellSearch (n=380). Optimal cutoffs for CTC-/DTC-positivity were selected using Monte-Carlo cross validation. Multivariate Cox regression analysis was performed to determine correlation between levels of CTCs/DTCs vs. distant recurrence-free survival (DRFS) and breast cancer-specific survival (BCSS). The overall median follow-up was 7.1 years for DRFS and and 9.1 years for BCSS, but extended up to 13.3 years in subset analyses (Table 1).

Results: CTC-positivity by CellSearch was associated with HER2-positivity (Fisher p=0.01). Using optimized cutoffs in multivariate analyses, we found that CTC-positive pts by CellSearch had a statistically significant increased risk of distant recurrence (HR 4.93, p=0.0067). Moreover, pts who were CTC-positive by IE/FC had a statistically significant increased risk of breast cancer-specific death (HR=3.54, p=0.0138). DTC status, by itself, was not prognostic; however, when combined with CTC status by IE/FC (n=273), positive detection for both (CTC+DTC+) was significantly associated with increased risk of distant recurrence (HR=3.09, p=0.0270) and breast cancer-specific death (HR=4.55, p=0.0205).

Table 1.Multivariate analysis to determine the prognostic significance of CTCs and DTCs detected at the time of surgery in treatment naive early breast cancer patients. Adjusted for age at diagnosis, tumor size, pathologic stage, HR and HER2 status, node status and grade.  DRFS  BCSS  Variable and Method% positiveHR [95% CI]Wald p-valueMedian f/u [range] Years*HR [95% CI]Wald p-valueMedian f/u [range] Years*CTC+ vs. CTC- by CellSearch94.93[1.56-15.6]0.00676.4 [0.16-13.8]4.50[0.76-26.5]0.09627.5 [0.71-15.0]CTC+ vs. CTC- by IE/FC401.92[0.93-3.95]0.07599.8 [0.09-18.5]3.54[1.29-9.72]0.013813.3 [1.93-18.5]DTC+ vs. DTC- by IE/FC181.46[0.75-2.81]0.26317.5 [0.09-18.5]1.48[0.64-3.42]0.35429.8 [1.55-18.5]CTC+DTC+ vs. CTC-DTC- by IE/FC8**3.09[1.14-8.40]0.02709.8 [0.09-18.5]4.55[1.26-16.39]0.020513.3 [1.93-18.5]*f/u - follow-up; **double positive

Conclusions: We demonstrate the impact of quantitative evaluation of CTCs and DTCs by IE/FC. Our large single institution dataset, in which CTCs and DTCs have been contemporaneously quantitated, has the longest patient follow-up. Simultaneous detection of CTCs and DTCs at the time of definitive surgery in treatment naïve EBC pts is an independent prognostic factor associated with increased long-term risk of distant recurrence and death due to breast cancer. Given the lack of early endpoints for low-risk patients, liquid biopsy may be an important consideration for future studies.

Citation Format: Magbanua MJM, Yau C, Wolf D, Lee JS, Chattopadhyay A, Scott JH, Yoder E, Hwang S, Alvarado M, Ewing CA, Delson AL, van't Veer L, Esserman L, Park JW. Detection of circulating tumor cells (CTC) in blood and disseminated tumor cells (DTC) in bone marrow at surgery identifies breast cancer patients (pts) with long-term risk of distant recurrence and breast cancer-specific death [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-02.