Baseline Circulating Tumor Cells Research Articles

Abstract PO1-16-02: Correlation of Circulating Tumor Cells (CTC) with Clinical Characteristics, Pathological Factors, and Treatment Response in Patients with Metastatic Breast Cancer (MBC)

Abstract Background: Circulating Tumor Cells (CTC) can be isolated in 40-80% of patients with metastatic breast cancer (MBC). High levels of CTC, defined as ≥5/7.5 ml of blood are associated with shorter progression-free survival and overall survival. CTC can be tested for clinically relevant biomarkers, such as ER, and HER2 status, and have the potential to guide therapy as well as help with disease monitoring. We investigated CTC detection rate, its correlation with clinical characteristics, pathological characteristics, and response to treatment in patients with any type of metastatic breast cancer who progressed on at least one line of therapy. Methods: Eligible patients with MBC were enrolled in the IMAGE-II study (Individualized Molecular Analyses Guide Efforts in Breast Cancer) NCT02965755, in which we obtained archival tissue as part of the standard of care, and prospectively collected serial blood samples for CTC analysis. We compared CTC levels and biomarker status with clinical factors, tissue-based pathology, and molecular biomarkers. We assessed whether changes in CTC count correlated with treatment response. Blood samples were collected at baseline (Day 1), after 1-2 weeks of therapy, after 8-12 weeks, and at subsequent restaging (every 8-12 weeks). Medical records were reviewed every 3 months for ongoing treatment response, and death. Samples were processed at the Biocept CLIA-certified Laboratory. CTC were enumerated by the presence of CD45- and DAPI+ cells. Further CTC characterization was performed by antibody staining of specific protein biomarkers (ER, HER2). Fisher’s exact test was used to evaluate the association between baseline CTC < 5 and ≥5/7.5ml with patient characteristics. McNemar’s test was used to assess discordance between tissue-based and CTC-defined markers. Results: Between 1/26/2018 and 12/31/22 baseline samples were collected from 70 women with a median age of 56 (36-82) who were enrolled at four study sites. CTC was detected in 59 (84%) of participants. Baseline CTC counts were < 5/7.5 ml in 37/59 (63%) and ≥5/7.5 ml in 22/59 (37%) of participants. Differences between breast cancer subtype and CTC-receptor status were observed (Table 1). Among the 41 patients who were ER-positive, 31 (76%) were CTC ER-negative(p< 0.001). Among 29 patients who were ER-negative, 4 (14%) were CTC ER-Positive (P< 0.001). Among the 7 patients who were HER2 positive, 2(29%) were HER2 positive on CTC. Among 63 patients who were HER2 negative, 7(11%) had HER2 expression on their CTC. The discordance in the classification of HER2 wasn't statistically significant (p=0.77). Elevated CTC at baseline was more frequently detected in younger participants (< 50 years old) (55% vs 27%; P=0.22), in Black women compared to White (60 % vs 29 %, P=0.27), and in participants with visceral vs non-visceral metastasis (52% vs 28 %, P=0.40). Patients with CTC ≥5 vs < 5/7.5mL at baseline had a shorter duration of anti-HER2-based therapy (61.5 vs 836 days, p=0.04). There were no statistically significant differences among participants who received chemotherapy agents (316.5 vs 365.5 days, P=0.88), endocrine therapy (376 vs 490 days, P=0.89), or overall therapy (272 vs 390 days, P=0.21). Conclusions: We observed significant differences in the expression of ER between tumor tissue and CTC, which can be partly due to tumor evolution over time. Additionally, participants who are young, Black, and those who have visceral metastasis may have higher CTC counts. Higher CTC counts were associated with a shorter duration of anti-HER2 therapy. Although it didn’t meet statistical significance, a similar trend was observed in patients who received chemotherapy and endocrine therapy. Table 1: MBC Tissue-Based Subtype and CTC-receptor status at baseline Citation Format: Asnakech Bayable, Tingchang Wang, Amanda Blackford, Jessica Tao, Jenna Canzoniero, Seoho Lee, Faith Too, Barbara Blouw, Mary Wilkinson, Rima Couzi, Antonio Wolff, Christie Hiton, Ben Park, Vered Stearns, Cesar Santa-Maria. Correlation of Circulating Tumor Cells (CTC) with Clinical Characteristics, Pathological Factors, and Treatment Response in Patients with Metastatic Breast Cancer (MBC) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-16-02.

Abstract PO3-06-14: Phase I/II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic triple-negative breast cancer

Abstract Background: Activation of the RAS/MAPK pathway is associated with reduced tumor-infiltrating lymphocytes and poor outcomes in triple-negative breast cancer (TNBC). This trial evaluated the efficacy of pembrolizumab in combination with binimetinib, a MEK inhibitor. Methods: Patients with unresectable locally advanced or metastatic TNBC with ≤ 3 prior lines of therapy were enrolled. Treatment includes a 2-week run-in with binimetinib followed by pembrolizumab. There were 2 dose levels (DL) with binimetinib at 45 mg at DL 0 and 30 mg at DL -1. A standard 3+3 design was used in Phase I, and Simon’s two-stage Optimal design was used in Phase II. PD-L1 22C3 was performed in archival samples with CPS ≥ 10 considered as positive (PD-L1+). Tumor-infiltrating lymphocytes (TILs) were quantified into 0, 1, 2, and 3+. Circulating tumor cells (CTC) and circulating cancer-associated macrophage-like cells (CAML) were isolated using CellSieve microfilters and immunofluorescently labeled with PD-L1 and p-ERK. Wilcoxon rank sum test, Chi-square test, Cox regression model, and Spearman correlation were used for analysis. Results: 22 patients were enrolled with a median age of 58 years old. Dose-limiting toxicity (DLT) was observed in 2 out of 4 patients in DL 0, with grade 3 ALT abnormality, flank pain, and nausea. In the next 6 patients in DL -1, there was 1 DLT with grade 3 AST/ALT abnormality. There were 17 patients treated with DL -1 and were evaluable for response. The objective response rate (ORR) was 29.41% (95% CI: 10.31-55.9) with 1 complete response (CR) and 4 partial responses (PR). The clinical benefit rate (CBR ≥ 24 weeks) was 35.29% (95% CI: 14.21-61.67). ORR in patients without liver metastases was 55.56% (95% CI: 21.20 - 86.30) and CBR was 66.67% (95% CI: 29.93-92.51). No response was observed in all 5 patients with liver metastases. There were 40.9% of patients with PD-L1 CPS ≥ 10. ORR in patients with PD-L1+ was 80%. However, 11.1% of patients with PD-L1 negative tumors also had an objective response and 44.4% of patients had clinical benefit ≥ 24 weeks. PD-L1 expression in archival tissue was associated with ORR (p 0.032) but not CBR (p 0.198), progression-free survival (PFS, p 0.373), and overall survival (p 0.348). TILs in archival tissue were also not associated with CBR (p 0.155) and PFS (p 0.157). One patient with TILs 0 had a stable disease ≥ 24 weeks and 2 patients TILs 1+ also had an objective response. We further evaluated blood-based biomarkers with CTC and CAML. Baseline PD-L1 in CAML (p 0.04) and decline in CAML size (p 0.02) after 1 cycle was significantly associated with CBR. However, baseline CTC count, CAML count (p 0.64), CAML size (p 0.46), p-ERK in CAML (p 0.23), and changes in CTC count, CAML count (p 0.83), p-ERK (p 0.07), and PD-L1 (p 0.08) in CAML were not significantly associated with responses. Using Cox regression analysis, a reduction in CAML count (p 0.02), CAML size (p 0.01), and PD-L1 in CAML (p 0.03) were associated with significant improvement in overall survival but not the reduction in p-ERK (p 0.6). However, PD-L1 expression in CAML is not associated with PD-L1 expression in archival tissue (Spearman correlation 0.13). Conclusions: Pembrolizumab and binimetinib at 30 mg are safe with manageable toxicities. Consistent with the preclinical data that MEKi can restore T cell function, promising activity was observed even in patients with low TILs and PD-L1 negative, particularly in patients without liver metastases. PD-L1 expression in peripheral blood CAML rather than archival tumor tissue may serve as a better biomarker to predict the clinical benefit of this combination. Early reductions in CAML count and size, were also significantly associated with responses. Future larger clinical trials are warranted to further evaluate the efficacy of this chemotherapy-free combination. Citation Format: Saranya Chumsri, Joseph Larson, Daniel Adams, Kathleen Tenner, Cha-Mei Tang, Morgan Weidner, Amanda Arnold, Dana Haley, Pooja Advani, Kostandinos Sideras, Alvaro Moreno-Aspitia, Edith Perez, Keith Knutson. Phase I/II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-06-14.

Circulating tumor cells help differentiate benign ovarian lesions from cancer before surgery: A literature review and proof of concept study using flow cytometry with fluorescence imaging.

Current tools are insufficient for distinguishing patients with ovarian cancer from those with benign ovarian lesions before extensive surgery. The present study utilized a readily accessible platform employing a negative selection strategy, followed by flow cytometry, to enumerate circulating tumor cells (CTCs) in patients with ovarian cancer. These counts were compared with those from patients with benign ovarian lesions. CTC counts at baseline, before and after anticancer therapy, and across various clinical scenarios involving ovarian lesions were assessed. A negative-selection protocol we proposed was applied to patients with suspected ovarian cancer and prospectively utilized in those subsequently confirmed to have malignancy. The protocol was implemented before anticancer therapy and at months 3, 6, 9 and 12 post-treatment. A cut-off value for CTC number at 4.75 cells/ml was established to distinguish ovarian malignancy from benign lesions, with an area under the curve of 0.900 (P<0.001). In patients with ovarian cancer, multivariate Cox regression analysis revealed that baseline CTC counts and the decline in CTCs within the first three months post-therapy were significant predictors of prolonged progression-free survival. Additionally, baseline CTC counts independently prognosticated overall survival. CTC counts obtained with the proposed platform, used in the present study, suggest that pre-operative CTC testing may be able to differentiate between malignant and benign tumors. Moreover, CTC counts may indicate oncologic outcomes in patients with ovarian cancer who have undergone cancer therapies.

Circulating and Imaging Biomarkers of Radium-223 Response in Metastatic Castration-Resistant Prostate Cancer.

Radium-223 improves overall survival (OS) and reduces skeletal events in patients with bone metastatic castration-resistant prostate cancer (CRPC), but relevant biomarkers are lacking. We evaluated automated bone scan index (aBSI) and circulating tumor cell (CTC) analyses as potential biomarkers of prognosis and activity. Patients with bone metastatic CRPC were enrolled on a prospective single-arm study of standard radium-223. 99mTc-MDP bone scan images at baseline, 2 months, and 6 months were quantitated using aBSI. CTCs at baseline, 1 month, and 2 months were enumerated and assessed for RNA expression of prostate cancer-specific genes using microfluidic enrichment followed by droplet digital polymerase chain reaction. The median OS was 21.3 months in 22 patients. Lower baseline aBSI and minimal change in aBSI (<+0.7) from baseline to 2 months were each associated with better OS (P = .00341 and P = .0139, respectively). The higher baseline CTC count of ≥5 CTC/7.5 mL was associated with worse OS (median, 10.1 v 32.9 months; P = .00568). CTCs declined at 2 months in four of 15 patients with detectable baseline CTCs. Among individual genes in CTCs, baseline expression of the splice variant AR-V7 was significantly associated with worse OS (hazard ratio, 5.20 [95% CI, 1.657 to 16.31]; P = .00195). Baseline detectable AR-V7, higher aBSI, and CTC count ≥5 CTC/7.5 mL continued to have a significant independent negative impact on OS after controlling for prostate-specific antigen or alkaline phosphatase. Quantitative bone scan assessment with aBSI and CTC analyses are prognostic markers in patients treated with radium-223. AR-V7 expression in CTCs is a particularly promising prognostic biomarker and warrants validation in larger cohorts.

Analysis of baseline circulating tumor cells integrated with PET/CT findings in transplant-ineligible multiple myeloma

We aimed to improve prognostic predictors in transplant-ineligible multiple myeloma (TIE-MM) patients by combining baseline circulating clonal tumor cells (CTCs) and positron emission tomography/computed tomography (PET/CT) findings. The factors associated with prognosis were retrospectively investigated in 126 TIE-MM patients who underwent CTC quantification by multiparameter flow cytometry and PET/CT at the initial presentation. The total lesion glycolysis (TLG) level was calculated using Metavol software. The median percentage of CTC was 0.06% (range, 0%–4.82%), and 54 patients (42.9%) demonstrated high CTC levels. High CTC levels were associated with significantly poorer progression-free survival (PFS, 2-year 43.4% vs. 68.1%, P <0.001) and overall survival (OS, 5-year 39.0% vs. 68.3%, P <0.001). Similarly, high TLG levels significantly worsened the PFS (2-year, 41.2% vs. 67.6%, P = 0.038) and OS (5-year, 37.7% vs. 63.1%, P = 0.019). The multivariate analyses showed that Revised International Staging System (R-ISS) III, high CTC and TLG levels, and complete response were significant prognostic factors for PFS and OS. A novel predictive model was constructed using CTCs, TLG, and R-ISS III. The patients were stratified into three groups according to the number of risk factors, revealing an extremely high-risk group with a 2-year PFS of 0% and a 5-year OS of 20%. Patients without any high-risk features had better prognosis, with a 2-year PFS of 78.6% and a 5-year OS of 79.5%. The combination of CTCs and volumetric assessment of PET/CT at diagnosis augments the existing stratification systems and may pave the way for a risk-adapted treatment approach.

Circulating tumor cells as a predictor and prognostic tool for metastatic clear cell renal carcinoma: An immunocytochemistry and genomic analysis

BackgroundTreatment of metastatic clear cell renal carcinoma (mccRCC) has changed dramatically over the past 20 years, without improvement in the development of biomarkers. Recently, circulating tumor cells (CTCs) have been validated as a prognostic and predictive tool for many solid tumors. ObjectiveWe evaluated CTCs in blood samples obtained from patients diagnosed with mccRCC. Comparisons of CTC counts, protein expression profiling, and DNA mutants were made in relation to overall survival and progression-free survival. MethodsCTCs were isolated from 10 mL blood samples using the ISET® system (Isolation by SizE of Tumor Cells; Rarecells, France) and counted. Protein expression was evaluated in immunocytochemistry assays. DNA mutations were identified with next generation sequencing (NGS). ResultsBlood samples (10 mL) were collected from 12 patients with mccRCC before the start of first-line systemic therapy, and again 30 and 60 days after the start of treatment. All 12 patients had CTCs detected at baseline (median, 1.5 CTCs/mL; range: 0.25–7.75). Patients with CTC counts greater than the median had two or more metastatic sites and exhibited worse progression-free survival (19.7 months) compared to those with CTC counts less than the median (31.1 months). Disease progression was observed in 7/12 patients during the study. Five of these patients had baseline CTC counts greater than the median, one had higher CTC levels at the second blood collection, and one patient had CTCs present at 1 CTC/mL which positively stained for PD-L1, N-cadherin, VEGF, and SETD2. CTC DNA from six patients with worse outcomes was subjected to NGS. However, no conclusions could be made due to the low variant allele frequencies. ConclusionDetection of CTCs in patients with mccRCC receiving first-line treatment is a feasible tool with prognostic potential since increased numbers of CTCs were found to be associated with metastasis and disease progression.

Prospective Characterization of Circulating Tumor Cells in Hormone Sensitive Oligometastatic Prostate Cancer Patients on a Metastasis-Directed Therapy Trial

Prospective data have shown that metastasis-directed therapy (MDT) can alter the natural history of oligometastatic disease. In hormone-sensitive prostate cancer (HSPC), the clinical effect of MDT has been validated by STOMP, ORIOLE and SABR-COMET phase II trials. Circulating tumor cells (CTCs) are likely the source for the formation of macroscopic metastases. CTCs may provide an approach for identifying subgroups of patients with oligometastatic HSPC (oligoHSPC) that would benefit most from MDT. Our main goal was to evaluate the feasibility of CTC detection and subtypes in oligoHSPC patients that may benefit from MDT. ORIOLE randomized men with recurrent HSPC with 1-3 metastases to observation (Obs) vs. stereotactic ablative radiotherapy (SABR) MDT. Blood samples were prospectively collected at baseline (D0) and 6-mos (D180) and shipped for analysis on Epic Sciences liquid biopsy platform (Epic Sciences, San Diego, CA). Machine learning algorithms identified CTCs and characterized androgen receptor (AR) and PSMA expression. Association with clinical factors and outcomes were examined. Biochemical failure-free survival (BFFS) event was a PSA rise of at least 2 ng/mL and 25% above nadir. Progression-free survival (PFS) was a composite endpoint including BFFS event, radiologic progression (RECIST v1.1); symptomatic progression; initiation of ADT; or death. Comparisons of patient and tumor characteristics performed by two-sample t-tests. Survival curves were generated by the Kaplan-Meier method and evaluated by the log-rank test. Effect of SABR on post-SABR on CTC levels were calculated by McNemar test. A total of 82 samples were collected in ORIOLE: 70 SABR (35 D0 and 35 D180) and 12 Obs (7 D0 and 5 D180). 30/42 men had CTCs detected on D0 (71%; AR+ = 7, PSMA+ = 13) and in 26/40 on D180 (65%; AR+ = 9, PSMA+ = 8). Median follow-up was 41.7-mos. There was no association between CTC presence or subtypes (AR+ or PSMA+) with Gleason score or PSA. PFS was significantly lower in the patients with AR+ vs. AR- CTCs on D0 in the SABR arm (p = 0.011, median PFS: AR+ = 9.3- vs. AR+ = 27.1-mos). The median BFFS trended towards a difference for AR+ = 12.9- vs. AR- = 29.2-mos (D180, p = 0.058). SABR had no effect on the presence or subtypes of CTC at D180. Baseline and dynamic CTC levels and their subtypes in oligoHSPC from the ORIOLE randomized trial of MDT was examined. AR+ CTCs at baseline and 6-mos were correlated with clinical outcomes following SABR. Longer follow-up, further analysis and a greater number of patients are needed for a more comprehensive conclusion.

HER2 Expression in Circulating Tumor Cells as Prognostic and Predictive Biomarkers for Anti‐HER2 Therapy in Previously Treated Metastatic Colorectal Cancer

AbstractFor human epidermal growth factor receptor 2‐positive metastatic colorectal cancer (HER2+ mCRC), anti‐HER2 therapy shows benefits, while current HER2 testing using tumor biopsy remains controversial. Noninvasive circulating tumor cells (CTCs) may achieve more accurate HER2 diagnosis . Herein, enumeration and HER2 phenotyping on CTCs (HER2(0/1+/2+/3+) CTCs) are assessed using TUMORFISHER for 40 mCRC patients (20 HER2+; 20 HER2‐negative). Positive/negative HER2 phenotypes on CTCs (ctcHER2+/‐) are determined with or without &gt; 5% HER2(2+/3+) CTCs. After anti‐HER2 therapy, HER2+ patients without baseline CTCs show significantly better survivals than those with 1 ≤ CTCs ≤ 51 or ≥ 52 CTCs at baseline (mPFS; 5.6, 4.2, and 2.0 months; p = 0.0021) (mOS; not yet reached, 18.0 and 9.1 months; p = 0.0002). Among HER2+ patients with 1 ≤ CTCs ≤ 51 at baseline, ctcHER2+ has more favorable survivals than ctcHER2– (mPFS; 5.1 and 2.3 months; p = 0.0257) (mOS; not yet reached, 14.7 months; p = 0.0400). HER2+ patients with ≥ 52 CTCs or (with 1 ≤ CTCs ≤ 51 and maintained ctcHER2–) show a higher progression disease rate (60.0%, 0.0%; p = 0.0106). Therefore, CTC enumeration and ctcHER2 phenotyping may be prognostic and predictive biomarkers for HER2+ mCRC with anti‐HER2 therapy.

Longitudinal Assessment of Circulating Tumor Cells and Outcome in Small Cell Lung Cancer: A Sub-Study of RASTEN-A Randomized Trial with Low Molecular Weight Heparin.

Circulating tumor cells (CTCs) may provide a liquid biopsy approach to disease monitoring in small cell lung cancer (SCLC), a particularly aggressive tumor subtype. Yet, the prognostic role of CTCs during and after treatment in relation to baseline remains ill-defined. Here, we assessed the value of longitudinal CTC analysis and the potential of low-molecular-weight heparin (LMWH) to reduce CTC abundance in SCLC patients from a randomized trial (RASTEN). Blood samples were collected at baseline, before chemotherapy Cycle 3, and at 2-month follow-up from 42 patients in total, and CTCs were quantified using the FDA-approved CellSearch system. We found a gradual decline in CTC count during and after treatment, independently of the addition of LMWH to standard therapy. Detectable CTCs at baseline correlated significantly to reduced survival compared to undetectable CTCs (unadjusted hazard ratio (HR) of 2.75 (95% CI 1.05-7.20; p = 0.040)). Furthermore, a persistent CTC count at 2-month follow-up was associated with a HR of 4.22 (95% CI 1.20-14.91; p = 0.025). Our findings indicate that persistently detectable CTCs during and after completion of therapy offer further prognostic information in addition to baseline CTC, suggesting a role for CTC in the individualized management of SCLC.

Circulating tumor cells in patients with hormone receptor-positive, HER2-negative metastatic breast cancer receiving palbociclib with fulvestrant after progression on palbociclib with an aromatase inhibitor.

e13018 Background: High levels of circulating tumor cells (CTCs) at initiation of therapy in patients with metastatic breast cancer (MBC) are associated with worse prognosis. In patients with hormone receptor–positive (HR+), HER2-negative MBC, the benefit of maintaining CDK4/6 inhibitor (CDK4/6i) after progression on first-line therapy with endocrine therapy and CDK4/6i is not fully defined. To study the relationship between CTCs, tumor characteristics, and clinical outcomes, we enumerated CTC dynamics in patients with HR+ HER2- MBC enrolled on a phase II, multi-center, open-label interventional trial of palbociclib and fulvestrant after disease progression on prior palbociclib with an aromatase inhibitor (NCT02738866). Methods: Blood samples from study participants were collected at baseline (pretreatment), cycle 2 (C2, 8 weeks after initiation of fulvestrant and palbociclib), and at disease progression. Using a previously analytically validated assay (CellSearch), CTCs were enumerated. Progression-free survival (PFS) was estimated using the Kaplan Meier method. The relationship between CTC count at baseline (&lt; 5, &gt;5/7.5 ml Whole Blood (WB)) and PFS was analyzed using Cox proportional hazards regression. The association between PFS and CTC count among patients with baseline CTC ≥5 was estimated with a Cox proportional hazards model, adjusting for age, race, and progesterone receptor (PgR). Results: Between May 2017 and September 2022, baseline samples were collected from 52 of 60 trial participants enrolled at 5 centers in the United States, mean age 55 years (SD 14). Baseline CTC counts were &lt;5 in 30/52 (58%) and &gt;5 in 22/52 (42%) of participants. Among participants at baseline, only tissue PgR negativity was associated with higher likelihood of having elevated CTCs &gt;5 (p = 0.04). Association of CTCs &gt;5 and select patient and tumor characteristics is shown in Table 1. There was no statistically significant association between continuously measured CTC and PFS among those with elevated CTCs at baseline. Median duration of therapy among the entire 52 participant cohort was 4 months. Median PFS in participants with baseline CTC &lt;5 vs &gt;5/7.5 ml WB was 7.83 (95% CI [5.37, 12.60]) and 2.83 (95% CI [1.77, 4.73]) months, respectively (HR): 2.10, 95% CI [1.15, 3.82], p = 0.01). Conclusions: Baseline CTCs &gt;5/7.5 ml WB conferred a 2-fold increased risk of disease progression. Tissue PgR negativity was associated with baseline CTCs &gt;5. These data can be used to inform new studies in which baseline and early change in CTCs may inform second line treatment decisions in women with HR+, HER2- MBC. [Table: see text]

Circulating tumor cells (CTCs) dynamics after CDK4/6i for hormone-receptor positive (HR+) metastatic breast cancer (MBC): A biomarker analysis of the PACE randomized phase II study.

1059 Background: PACE is a multicenter randomized phase II trial investigating palbociclib (P) in combination with fulvestrant (F) after progression on any CDK4/6 inhibitor (CDK4/6i), with or without the PD-L1 inhibitor avelumab (A), in HR+/HER2- MBC. CTCs are rare cells in the blood stream whose detection is associated with worse outcome and treatment resistance. Methods: Eligible patients (pts) had HR+/HER2- MBC with prior progression after ≥ 6 months (mo) of AI and CDK4/6i for MBC, or during/within 12 mo in the adjuvant setting, with ≤ 1 prior chemotherapy for MBC. Pts were randomized 1:2:1 to F, F+P, or F+P+A. CTC detection and enumeration were performed utilizing CellSearch (Menarini Silicon Biosystems) at baseline (BL), at time of first tumor assessment (TTA1), and at progression. Results were dichotomized using the standard CTC threshold (≥ 5 CTCs/7.5 ml) into a novel prognostic classification: StageIVindolent and StageIVaggressive (Cristofanilli et al 2019). Concurrent ctDNA Sequencing was performed using Guardant360 (Guardant Health). Results: Of the 220 randomized pts, 203 (92%) had sample available for BL CTC enumeration, 155 had detectable CTCs (70.5%), and 99 (48.8%) were StageIVaggressive. De novo disease at initial diagnosis was associated with StageIVaggressive (47.5% vs 30.8% StageIVindolent), and distribution of visceral versus non-visceral disease was similar across the two CTCs groups. StageIVaggressive represented 38.3%, 54.8%, and 46.2% of the F, F+P and F+P+A treatment groups, respectively. BL CTCs were prognostic in the overall cohort; median PFS was 5.7mo vs 3.5mo for StageIVindolent vs StageIVaggressive (HR: 1.69, 90%CI 1.27,2.24, P&lt;0.001). Median PFS for the F, F+P and F+P+A arms was 1.9mo, 4.6mo and 5.4mo in StageIVaggressive compared to 8.2mo, 5.3mo and 8.3mo in StageIVindolent. Among patients in the StageIVaggressive subgroup, the F+P and F+P+A arms demonstrated improved outcomes compared to F alone. (F+P vs F HR 0.43, 90% CI 0.25-0.71, and F+P+A vs F HR 0.26, 90% CI 0.14-0.49). No benefit of F+P or F+P+A over F was observed in the StageIVindolent subgroup (F+P vs F HR 1.45, 90% CI 0.87 - 2.40 and F+P+A vs F HR 1.06, 90% CI 0.61 - 1.84, each p(interaction)&lt;0.01). Changes in StageIV CTC characterization (indolent vs aggressive) between BL and TTA1 among the subset of 175/203 pts with both timepoints available are reported. Conclusions: Baseline CTC enumeration is prognostic in patients receiving F with or without CDK4/6i. The StageIVaggressive subgroup may derive preferential benefit with combinations of F+P or F+P+A over F alone. Findings should be confirmed in other studies. ctDNA analyses are ongoing. Clinical trial information: NCT03147287 . [Table: see text]

A phase II study of olaparib (AZD2281) in patients (Pts) with metastatic/advanced urothelial carcinoma and other genitourinary (GU) tumors with DNA-repair defects.

TPS4607 Background: Olaparib is a poly-ADP-ribose polymerase (PARP) inhibitor that induces synthetic lethality in tumor cells with dysfunctional DNA damage repair (DDR) from loss of function of BRCA or other DDR genes. It improves survival in advanced ovarian, pancreatic, prostate and breast carcinoma with DDR gene alterations and is FDA approved for these indications. PARP inhibitors still have an undefined role in non-prostate GU tumors. We hypothesize that PARP inhibitors will have activity in DDR deficient tumors, regardless of histology. We are conducting a phase 2 trial of olaparib in non-prostate GU cancers with DDR gene defects. Methods: Eligible pts must have metastatic/advanced urothelial carcinoma or other non-prostate GU cancers and have measurable disease by RECIST 1.1. Pts in Cohorts 1 and 2 must harbor tumor or liquid pathologic DDR alterations identified by FoundationOne CDx (F1CDx) panel and reviewed by a molecular genetics review panel: Cohort 1 includes BRCA1, BRCA2, ATM, BAP1, MSH2, PALB2, and BRIP1 alterations, and pts with high tumor mutational burden (TMB) (&gt;15 mutations/megabase); Cohort 2 (exploratory cohort) includes ABL1, ATR, ATRX, BARD1, BRD4, CCND1, CHEK1, CHEK2, DOTIL, FANCC, FANCE, FANCG, FANCL, IKBKE, MEN1, MLH1, MSH2, MSH6, MUTYH, NPM1, PMS2, POLD1, POLE, RAD51, SMARCB1, STEK11, and TP53 alterations. Cohort 3 (natural history) will include pts without pathologic alterations in any Cohort 1 or 2 genes. Pts with eligible gene alterations (Cohorts 1 and 2) will be given olaparib 300mg twice daily until progressive disease, unacceptable adverse events, withdrawal of consent or death. They will have circulating tumor cells (CTCs) collected at baseline and every 4 weeks, and CT restaging every 8 weeks. Pts in Cohort 3 will receive standard of care treatment and have baseline CTC collection and be followed for survival. The primary objective is to evaluate the objective response rates (ORR) in Cohorts 1 and 2. Secondary objectives include progression-free survival (PFS), overall survival (OS) and safety. In these cohorts, the trial will have a Simon optimal two-stage design. In Cohort 1, 25 evaluable pts will be required to provide 90% power with alpha = 0.1 to differentiate between a promising ORR of 30% versus an unacceptably low ORR of 10%. In Cohort 2, 35 evaluable pts will be required to provide 90% power with alpha = 0.05 to differentiate between a promising ORR of 30% versus an unacceptably low ORR of 10%. Exploratory objectives include estimating the distribution of DDR alterations in non-prostate GU malignancies, assessing the effectiveness of NGS in detecting DDR alterations in circulating tumor DNA (ctDNA), assessing levels of baseline CTCs and changes in CTC level with olaparib, and correlating with clinical outcomes. This is an ECTCN network clinical trial and is open to enrollment. Clinical trial information: NCT03375307 .

Baseline circulating tumor cell (CTC) count as a prognostic marker of overall survival (OS) in metastatic hormone sensitive prostate cancer (mHSPC): Results from SWOG S1216, a phase III randomized trial of androgen deprivation plus orteronel (cyp17 inhibitor) or bicalutamide.

5080 Background: Biomarkers are needed to predict clinical outcomes in mHSPC. We previously reported that baseline CTC counts in S1216 were prognostic of PSA response and disease progression ( ASCO 2020; CCR 2021). However, the trial’s primary overall survival (OS) endpoint was not yet mature at that time. Here we present the final results of S1216 using all available samples to assess the prognostic value of CTC counts for response, progression, OS, and treatment arm interactions. Methods: In S1216, peripheral blood was drawn with informed consent at registration (baseline) and at progression to metastatic castrate resistant prostate cancer (mCRPC). CTCs were enumerated on the FDA-cleared CellSearch platform (Menarini). CTC counts were evaluated for associations with 3 pre-specified trial endpoints: 7-month PSA (7mPSA) ≤ 0.2 ng/ml vs. 0.2–4.0 vs. &gt; 4.0 using a generalized logit model; and progression-free survival (PFS) and OS using Cox regression. Results: From 2014 to 2021, 503 evaluable samples were collected at baseline and 93 at progression. Baseline CTC count was ≥5 in 11.9% of samples, 1-4 in 19.3%, and 0 in 66.8%. Comparing men with 0 vs. ≥5 CTCs at baseline, those with 0 CTCs were significantly more likely to attain a complete PSA response and had significantly lower risk of a PFS event and death after adjusting for clinical covariates (disease burden, bone metastases, age, race, alkaline phosphatase, hemoglobin, PSA, treatment arm). These associations were not modified by treatment arm. Progression CTCs &lt;5 vs. ≥5 also were prognostic of OS (logrank p=0.001), consistent with prior findings in mCRPC. Same-patient CTC counts in matched baseline-progression pairs (n=61) were highly correlated (Spearman p&lt;0.001). Conclusions: CTC count at the start of treatment for mHSPC was highly prognostic of PSA response, PFS, and OS; associations that held in both treatment arms. Moreover, baseline CTC count strongly correlated with progression count, suggesting that mild vs. aggressive disease phenotypes may persist from mHSPC to mCRPC. This evidence from a large prospective phase 3 trial suggests that baseline CTC count is a valuable prognostic marker in men initiating therapy for mHSPC, discriminating those likely to experience favorable vs. unfavorable response and OS. [Table: see text]

Circulating tumor cell abundance in head and neck squamous cell carcinoma decreases with successful chemoradiation and cetuximab treatment

Head and neck squamous cell carcinoma (HNSCC) is a common and deadly cancer. Circulating tumor cell (CTC) abundance may a valuable, prognostic biomarker in low- and intermediate-risk patients. However, few technologies have demonstrated success in detecting CTCs in these populations. We prospectively collected longitudinal CTC counts from two cohorts of patients receiving treatments at our institution using a highly sensitive device that purifies CTCs using biomimetic cell rolling and dendrimer-conjugated antibodies. In patients with intermediate risk human papillomavirus (HPV)-positive HNSCC, elevated CTC counts were detected in 13 of 14 subjects at screening with a median of 17 CTC/ml (range 0.2–2986.5). A second cohort of non-metastatic, HPV- HNSCC subjects received cetuximab monotherapy followed by surgical resection. In this cohort, all subjects had elevated baseline CTC counts median of 73 CTC/ml (range 5.4–332.9) with statistically significant declines during treatment. Interestingly, two patients with recurrent disease had elevated CTC counts during and following treatment, which also correlated with growth of size and ki67 expression in the primary tumor. The results suggest that our device may be a valuable tool for evaluating the success of less intensive treatment regimens.

Abstract 5454: Peripheral blood biomarkers in Phase II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic triple-negative breast cancer

Abstract Background: Activation of the RAS/MAPK pathway is associated with reduced tumor-infiltrating lymphocytes and poor outcomes in triple-negative breast cancer (TNBC). This trial evaluated the efficacy of pembrolizumab and MEK inhibitor, binimetinib. Here we evaluated potential biomarkers in peripheral blood to predict response. Methods: Patients with unresectable locally advanced or metastatic TNBC with ≤ 3 prior lines of therapy were enrolled. Treatment includes a 2-week run-in with binimetinib followed by pembrolizumab. There were 2 dose levels (DL) with binimetinib at 45 mg at DL 0 and 30 mg at DL -1. A standard 3+3 design was used in phase I, and Simon’s two-stage Optimal design was used in phase II. Circulating tumor cells (CTC) and circulating cancer-associated macrophage-like cells (CAML) were isolated using CellSieve microfilters and immunofluorescently labeled with PD-L1 and p-ERK. Wilcoxon rank sum test and Cox regression model were used for analysis. Results: A total of 22 patients were enrolled, with a median age of 58 years old. Dose-limiting toxicity (DLT) was observed in 2 out of 4 patients in DL 0, with grade 3 ALT abnormality, flank pain, and nausea. In the next 6 patients in DL -1, there was 1 DLT with grade 3 AST/ALT abnormality. There were 17 patients treated with DL -1 and were evaluable for response. The objective response rate (ORR) was 29.41% (95% CI: 10.31-55.9) with 1 complete response (CR) and 4 partial responses (PR). The clinical benefit rate (CBR ≥ 24 weeks) was 35.29% (95% CI: 14.21-61.67). ORR in patients without liver metastases was 55.56% (95% CI: 21.20 - 86.30), and CBR was 66.67% (95% CI: 29.93-92.51). There was no response observed in all 5 patients with liver metastases. Baseline mean CTC count was 1.3 cells, and CAML count was 8.9 cells/7.5 mL. Baseline PD-L1 in CAML (p 0.04) and decline in CAML size (p 0.02) after 1 cycle were significantly associated with CBR. However, baseline CTC count, CAML count (p 0.64), CAML size (p 0.46), p-ERK in CAML (p 0.23), and changes in CTC count, CAML count (p 0.83), p-ERK (p 0.07), and PD-L1 (p 0.08) in CAML were not significantly associated with responses. Using Cox regression analysis, a reduction in CAML count (p 0.02), CAML size (p 0.01), and PD-L1 in CAML (p 0.03) were associated with significant improvement in overall survival but not the reduction in p-ERK (p 0.6). Conclusions: Pembrolizumab and binimetinib at 30 mg are safe with manageable toxicities. Promising activity was observed in patients without liver metastases. Baseline PD-L1 expression, early reduction in CAML count, size, and PD-L1 expression were significantly associated with subsequent responses, providing potential noninvasive biomarkers to predict response to this combination. Future larger clinical trials are warranted to further evaluate the efficacy of this combination. Citation Format: Saranya Chumsri, Joseph J. Larson, Daniel L. Adams, Kathleen S. Tenner, Cha-Mei Tang, Morgan T. Weidner, Amanda N. Arnold, Dana L. Haley, Pooja Advani, Kostandinos Sideras, Alvaro Moreno-aspitia, Edith A. Perez, Keith L. Knutson. Peripheral blood biomarkers in Phase II study of pembrolizumab in combination with oral binimetinib in patients with unresectable locally advanced or metastatic triple-negative breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5454.

MP29-10 PROGNOSTIC VALUE OF NEUTROPHIL-TO-LYMPHOCYTE RATIO (NLR) IN PATIENTS WITH METASTATIC CASTRATION-RESISTANT PROSTATE CANCER (MCRPC) RECEIVING PROSTATE-SPECIFIC MEMBRANE ANTIGEN (PSMA) TARGETED RADIONUCLIDE THERAPY (TRT)

You have accessJournal of UrologyCME1 Apr 2023MP29-10 PROGNOSTIC VALUE OF NEUTROPHIL-TO-LYMPHOCYTE RATIO (NLR) IN PATIENTS WITH METASTATIC CASTRATION-RESISTANT PROSTATE CANCER (MCRPC) RECEIVING PROSTATE-SPECIFIC MEMBRANE ANTIGEN (PSMA) TARGETED RADIONUCLIDE THERAPY (TRT) Judith Stangl-Kremser, Michael Sun, Benedict Ho, Joseph Thomas, Jones Nauseef, Joseph Osborne, Ana Molina, Cora Sternberg, David Nanus, Neil Bander, and Scott Tagawa Judith Stangl-KremserJudith Stangl-Kremser More articles by this author , Michael SunMichael Sun More articles by this author , Benedict HoBenedict Ho More articles by this author , Joseph ThomasJoseph Thomas More articles by this author , Jones NauseefJones Nauseef More articles by this author , Joseph OsborneJoseph Osborne More articles by this author , Ana MolinaAna Molina More articles by this author , Cora SternbergCora Sternberg More articles by this author , David NanusDavid Nanus More articles by this author , Neil BanderNeil Bander More articles by this author , and Scott TagawaScott Tagawa More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003257.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: PSMA TRT is a promising therapy for patients with mCRPC. Known prognostic factors for mCRPC include CALGB (Halabi) risk group and baseline circulating tumor cell (CTC) count. Here, we report associations between NLR and PSA response and overall survival (OS) in men with mCRPC treated on sequential prospective clinical trials at a single institution. METHODS: Patients treated on prospective studies from 2000 to 2021 were included in this analysis. Variables assessed: baseline neutrophil count:lymphocyte count ratio, baseline CTC count (CellSearch, favorable vs unfavorable), CALGB risk group, and administered radioactivity level. We used a Cox proportional hazards model to investigate the association between NLR and OS and logistic regression to determine the association between NLR and >50% PSA decline (PSA50). RESULTS: 180 patients were included in this analysis. Median age 71 (IQR 66-77.5), PSA 57.3 ng/mL (21.3-294.9), 80 (44.4%) prior chemotherapy, 86 (47.7%) prior abiraterone or androgen receptor signaling inhibitor, 167 (92.8%) bone metastases, 141 (78.3%) nodal metastases, 113 (62.8%) CALGB high-risk group. 94 (52.2%) received 177Lu-J591, 51 (28.3%) 177Lu-PSMA-617, 28 (15.6%) 225Ac-J591, 7 (3.9%) 90Y-J591. Median ANC 4.1 (IQR 3.1-5.1), ALC 1 (0.75-1.5), NLR 3.75 (2.63-5.92). On univariate analysis, higher NLR was associated with worse OS (HR 1.06, 95%CI 1.02-1.09, p=0.002) and trended toward lower rates of PSA50 (HR 1.08; 95% CI 0.99-1.17, p=0.067). On multivariable analysis, after controlling for CTC count and CALGB risk group, the relationship between higher NLR and worse OS persisted (HR 1.05; 95% CI 1.003-1.11, p=0.036). Stratifying patients by low vs high NLR (relative to median NLR), patients with low NLR had longer OS (23.7 vs 15 months, p=0.024). CONCLUSIONS: For patients with mCRPC receiving PSMA TRT, NLR may have prognostic implications with higher NLR associating with lower likelihood of PSA response and shorter overall survival. Source of Funding: NIH, Department of Defense, Weill Cornell Medicine, Prostate Cancer Foundation © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e384 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Judith Stangl-Kremser More articles by this author Michael Sun More articles by this author Benedict Ho More articles by this author Joseph Thomas More articles by this author Jones Nauseef More articles by this author Joseph Osborne More articles by this author Ana Molina More articles by this author Cora Sternberg More articles by this author David Nanus More articles by this author Neil Bander More articles by this author Scott Tagawa More articles by this author Expand All Advertisement PDF downloadLoading ...

Baseline CTC Count as a Predictor of Long-Term Outcomes in High-Risk Prostate Cancer.

The aim of the present study was to verify whether the baseline circulating tumor cell (CTC) count might serve as a predictor of overall survival (OS) and metastasis-free survival (MFS) in patients with high-risk prostate cancer (PCa) during a follow-up period of at least 5 years. CTCs were enumerated using three different assay formats in 104 patients: the CellSearch® system, EPISPOT assay and GILUPI CellCollector. A total of 57 (55%) patients survived until the end of the follow-up period, with a 5 year OS of 66% (95% CI: 56-74%). The analysis of univariate Cox proportional hazard models identified a baseline CTC count ≥ 1, which was determined with the CellSearch® system, a Gleason sum ≥ 8, cT ≥ 2c and metastases at initial diagnosis as significant predictors of a worse OS in the entire cohort. The CTC count ≥ 1 was also the only significant predictor of a worse OS in a subset of 85 patients who presented with localized PCa at the baseline. The baseline CTC number did not affect the MFS. In conclusion, the baseline CTC count can be considered a determinant of survival in high-risk PCa and also in patients with a localized disease. However, determining the prognostic value of the CTC count in patients with localized PCa would optimally require longitudinal monitoring of this parameter.

In vivo detection demonstrates circulating tumor cell reduction instead of baseline number has prognostic value in bladder cancer patients receiving neoadjuvant chemotherapy

Previous studies have suggested the potential prognostic value of circulating tumor cells (CTCs) in bladder cancer (BC) patients. This study aims to validate the prognostic value of in vivo detection of CTCs in muscle invasive bladder cancer (MIBC) patients receiving neoadjuvant chemotherapy (NAC). A total of 107 MIBC patients were enrolled in this study. All patients had one in vivo detection of CTCs before initial treatment as baseline, and those who received neoadjuvant chemotherapy (NAC) had a second detection after NAC and before radical cystectomy. CTCs dynamic change after NAC was analyzed. Prognostic value of in vivo CTCs detection was investigated. Among 68 patients who received NAC, 45 patients (66%) had a CTC reduction after NAC. CTC reduction instead of baseline CTC positivity was a key prognostic factor for better progression free survival (PFS) among all MIBC patients receiving NAC in Kaplan-Meier analysis (P < 0.01) and in both crude (HR 6.14, 95%CI 1.63-23.21) and adjusted regression model (HR 6.76, 95% CI 1.59-28.88). The AUC was 0.85. Our study demonstrated the prognostic value of in vivo detection of CTCs. The dynamic change of CTCs count may help evaluate the efficacy of NAC.

Abstract GS3-09: GS3-09 Circulating Tumor Cells-driven choice of first line therapy for ER+ HER2- metastatic breast cancer: overall survival analysis of the randomized STIC CTC trial

Abstract Background: High circulating tumor cell (CTC) count (CTChigh) is a strong adverse prognostic factor in patients with metastatic breast cancer (mBC). In the STIC CTC trial (NCT01710605), run before the introduction of CDK4/6 inhibitors for ER+/HER2- mBC, we showed that CTC count (CTC arm) was non inferior to clinician’s choice (standard arm) on progression-free survival (PFS) to guide first line treatment selection between chemotherapy (CT) and endocrine therapy (ET) (Bidard et al., JAMA Oncol 2021). Of note, patients who had treatment escalated from ET (a priori clinician choice) to CT in the CTC arm, had a significantly longer PFS. We report here overall survival (OS) results of this multicenter CTC clinical utility trial. Methods: In the CTC arm, N=377 patients had their treatment determined by baseline CTC count: CT if CTChigh (≥5 CTCs/7.5 mL, CellSearch®), ET if CTClow. In the standard arm (N=378 patients), the choice was left to the investigator: CT if clinical high risk (Clinhigh), ET if clinical low risk (Clinlow). Therefore, patients with discordant Clinlow/CTChigh or Clinhigh/CTClow profiles had their first line treatment escalated from ET (standard arm) to CT (CTC arm) or de-escalated from CT (standard arm) to ET (CTC arm), respectively. Patients with concordant Clinlow/CTClow and Clinhigh/CTChigh profiles received ET and CT in both arms, respectively. Results: Among 755 randomized patients, N=189 (25.0%) had a Clinlow/CTChigh profile, N=103 (13.6%) Clinhigh/CTClow, N=363 (48.2%) Clinlow/CTClow and N=100 (13.2%) Clinhigh/CTChigh. OS was analyzed after a median follow-up of 57 months and 382 events (50.6%). In the Clinlow/CTChigh subgroup, CT in the CTC arm led a longer OS (mOS: 51.8 months [43.3-NR]) than ET in the standard arm (35.4 months [30.4-45.4]; HR=0.53 [0.36-0.78], p=0.001). In patients Clinhigh/CTClow, no significant difference was observed whether they received CT (standard arm) or ET (CTC arm) (45.9 months [36.3-59.8] vs 49.4 months [35.4-65.4]; HR=0.88 [0.51-1.51], p=0.63). Pooling the two discordant groups (Clinlow/CTChigh or Clinhigh/CTClow), the CTC-driven strategy was superior to the clinician-driven treatment decision (HR=0.63 [0.46-0.86], p=0.02). Pooling all concordant and discordant groups together, a median OS of 45.5 (95%CI=[40.9-51.1]) and 51.3 months [46.8-55.1] was observed in the standard and CTC arms, respectively (HR=0.84 [0.69-1.03], p=0.10). Conclusions: Prognostic information brought by CTC or standard factors is discordant in 40% of patients with ER+ HER2- mBC. In case of a discordant estimate, the STIC CTC trial shows the superiority on OS of the CTC-driven treatment decision strategy. These results also suggest a possible clinical utility of CTC to adjust systemic treatment for mBC in second and later lines, after progression on CDK4/6 inhibitors. Funding:The study was funded by Institut Curie; the French National Cancer Institute (INCa), as part of the Programme de Soutien aux Techniques Innovantes Coûteuses 2011 (STIC 2011); and Menarini Silicon Biosystems (Castel Maggiore, Italy). Citation Format: Francois-Clement Bidard, Nicolas Kiavue, Catherine Alix-Panabières, Sylvain Dureau, Thomas Bachelot, Hugues Bourgeois, Anthony Gonçalves, Etienne Brain, Sylvain Ladoire, Florence Dalenc, Joseph Gligorov, Luis Teixeira, George Emile, Jean-Marc Ferrero, Delphine Loirat, Luc Cabel, Véronique Diéras, Frédérique Berger, William Jacot, Jean-Yves Pierga. GS3-09 Circulating Tumor Cells-driven choice of first line therapy for ER+ HER2- metastatic breast cancer: overall survival analysis of the randomized STIC CTC trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS3-09.

Abstract P6-01-29: Serial genomic analysis of circulating free DNA and change of immune-related gene signature in triple negative and HER2 positive advanced, metastatic breast cancer

Abstract Background: Circulating tumor cells (CTCs) and circulating free DNA (cfDNA) have a promising role for detecting early response and progression in breast cancer. Furthermore, change of immune-related gene signature during systemic treatment influence the treatment response of breast cancer. Herein we report the outcome of serial genomic analysis of CTC, cfDNA and change of immune-related gene signature in advanced, metastatic triple negative breast cancer (TNBC) and HER2 positive breast cancer (BC). Methods: Serial whole blood were prospectively collected in 18 early or advanced, and 10 metastatic BC patients periodically during systemic chemotherapy. CTC was isolated from whole blood through EpCAM positive bead selection, and ctDNA was isolated from plasma. For genomic profiling of CTC and ctDNA, Oncomine™ Comprehensive Assay Plus and Oncomine™ Pan-Cancer cfDNA assay (included BRCA1, BRCA2 and MYCN customized panel) was performed and analyzed, respectively. Total RNA was extracted using whole blood and analyzed using Nanostring Pancancer Immunology Panel. Results: Total 61 serial samples were obtained from 28 patients during the study. At baseline, FGFR4 mutation was the most commonly detected (10 patients, 76.9%) with median variant of allele frequency (VAF) of 54.5% (range 20.87~99.8%) in advanced and metastatic TNBC based on CTC analysis. In case of cfDNA, 11 patients (84.6%) showed TP53 mutation with low VAF (median 1.8%, range 0.1~12.3%). In HER2 positive BC, FGFR4 was also the most common mutation (5 patients [62.5%]; median VAF 57.9%) in CTC analysis and TP53 was most frequently detected (5 patients, [62.5%]; median VAF 3.0%) in cfDNA analysis. In three pathogenic gBRCA1 mutated patients, BRCA1 was identically detected in 2 patients based on CTC analysis and in 3 patients based on cfDNA analysis with VAF of approximately 50%. There were no significant changes of VAF in target mutations of CTC and cfDNA during systemic treatment, irrespective of tumor response and subtype. However, in one patients who harbored 13 mutations detected based on baseline CTC analysis, showed disappearance of 12 mutations in final CTC analysis with partial response based on radiologic findings. In contrary, there was another patient who gained multiple mutations during CTC analysis during neoadjuvant chemotherapy (NAC) with gain of tumor mutational burden (TMB). She did not achieve pathologic complete response and RCB score was 3 after completion of NAC. Most TNBC patients who received NAC and showed partial response, TMB showed gradual decrease during treatment. Baseline immune-related gene signatures were compared between HER2(+) BC and TNBC, and type 1 interferon signaling pathway was upregulated in HER2 (+) BC compared to TNBC. Conclusions: Our study suggest that serial follow up CTC and ctDNA, immune-related gene signature is feasible and reflect the general characteristics of baseline characteristics and dynamic molecular alteration of breast cancer. Further analysis with larger patient sample and correlation with tumor tissue is warranted in the future. Citation Format: Jieun Lee, Kabsoo Shin, Seung Yeon Joe, Hayoon Lee, Byung Hee Jeon, Ahwon Lee. Serial genomic analysis of circulating free DNA and change of immune-related gene signature in triple negative and HER2 positive advanced, metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-29.