Clinical applications of next-generation sequencing-based ctDNA analyses in breast cancer: defining treatment targets and dynamic changes during disease progression.

The advancements in the detection and characterization of circulating tumor DNA (ctDNA) have revolutionized precision medicine and are likely to transform standard clinical practice. The non-invasive nature of this approach allows for molecular profiling of the entire tumor entity, while also enabling real-time monitoring of the effectiveness of cancer therapies as well as the identification of resistance mechanisms to guide targeted therapy. Although the field of ctDNA studies offers a wide range of applications, including in early disease, in this review we mainly focus on the role of ctDNA in the dynamic molecular characterization of unresectable locally advanced and metastatic BC (mBC). Here, we provide clinical practice guidance for the rapidly evolving field of molecular profiling of mBC, outlining the current landscape of liquid biopsy applications and how to choose the right ctDNA assay. Additionally, we underline the importance of exploring the clinical relevance of novel molecular alterations that potentially represent therapeutic targets in mBC, along with mutations where targeted therapy is already approved. Finally, we present a potential roadmap for integrating ctDNA analysis into clinical practice.

Is the CTS5 a helpful decision-making tool in the extended adjuvant therapy setting?

PURPOSE: The Clinical Treatment Score post-5 years (CTS5) is an easy-to-use tool estimating the late distant recurrence (LDR) risk in patients with hormone receptor-positive breast cancer after 5 years of endocrine therapy (ET). Apart from evaluating the prognostic value and calibration accuracy of CTS5, the aim of this study is to clarify if this score is able to identify patients at higher risk for LDR who will benefit from extended ET. METHODS: Prognostic power, calibration, and predictive value of the CTS5 was tested in patients of the prospective ABCSG-06 and -06a trials (n = 1254 and 860 patients, respectively). Time to LDR was analyzed with Cox regression models. RESULTS: Higher rates of LDR in the years five to ten were observed in high- and intermediate-risk patients compared to low-risk patients (HR 4.02, 95%CI 2.26-7.15, p < 0.001 and HR 1.93, 95%CI 1.05-3.56, p = 0.035). An increasing continuous CTS5 was associated with increasing LDR risk (HR 2.23, 95% CI 1.74-2.85, p < 0.001). Miscalibration of CTS5 in high-risk patients could be observed. Although not reaching significance, high-risk patients benefitted the most from prolonged ET with an absolute reduction of the estimated 5-year LDR of - 6.1% (95%CI - 14.4 to 2.3). CONCLUSION: The CTS5 is a reliable prognostic tool that is well calibrated in the lower and intermediate risk groups with a substantial difference of expected versus observed LDR rates in high-risk patients. While a numerical trend in favoring prolonged ET for patients with a higher CTS5 was found, a significantly predictive value for the score could not be confirmed. CLINICAL TRIAL REGISTRATION: ABCSG-06 trial (NCT00309491), ABCSG-06A7 1033AU/0001 (NCT00300508).

Does the number of 6-monthly adjuvant zoledronate infusions received affect treatment efficacy for early breast cancer? A sub-study of ABCSG-12.

BACKGROUND: The widespread adoption of adjuvant bisphosphonate therapy for postmenopausal early breast cancer (EBC) patients was based on results of the Early Breast Cancer Trialist Group (EBCTCG) meta-analysis. Despite multiple regimens evaluated, there was no signal of varying efficacy with type, dose/dose intensity of bisphosphonate administration. We evaluated the effect of early treatment cessation using long-term outcome data from the ABCSG-12 trial. PATIENTS AND METHODS: ABCSG-12 randomized 1803 hormone-receptor positive EBC patients on ovarian suppression between 1999 and 2006 to receive 4 mg zoledronic acid 6-monthly or not (and tamoxifen or anastrozole, 2:2 factorial design). In the current study, we evaluated whether the number of zoledronate infusions had an impact on breast cancer-specific outcomes. We hypothesized that amongst patients who received at least one zoledronate infusion, the number of infusions had no effect on outcomes. Time-to-event endpoints were analysed with Cox models and Kaplan Meier curves starting from a 3-year landmark. BMD analysis was restricted to patients who participated in the BMD sub-study. RESULTS: 725 patients who received at least one zoledronate infusion were included in the time-to-event analysis. There was no statistically significant difference in disease-free or overall survival in the patients who received ≤6 zoledronate infusions (n = 170) compared to those who received ≥7 zoledronate infusions (n = 555). CONCLUSIONS: Comparable to efforts to de-escalate treatment duration in metastatic bone disease, there was no evidence to indicate that a reduced number of zoledronate infusions is associated with reduced adjuvant efficacy. Further studies to define optimal regimens of adjuvant bone-targeted therapies are required.

Influence of Height on Risk and Outcome of Patients with Early Breast Cancer: A Pooled Analysis of 4,925 Patients from 5 Randomized Trials of the Austrian Breast and Colorectal Cancer Study Group (ABCSG).

Background: Associations between height, cancer risk and worse outcome have been reported for several cancers including breast cancer. We hypothesized that in breast cancer clinical trials, tall women should be overrepresented and might have worse prognosis. Methods: Data of 4,935 women, included from 1990 to 2010 in 5 trials of the Austrian Breast and Colorectal Cancer Study Group (ABCSG), were analyzed retrospectively. The primary objective was to determine differences in height distribution between the ABCSG cohort and the Austrian female population according to a cross-sectional health survey conducted by the Austrian Statistic Center in 2006 and 2007. Secondary endpoints were disease-free survival (DFS) and overall survival (OS) in different height classes and differences of body mass index (BMI) distribution. Results: Breast cancer patients in the ABCSG cohort were only slightly but statistically significantly smaller compared to unselected Austrian adult females (mean 164.3 vs. 164.8 cm; p < 0.0001) and significantly more patients were seen in the lower body height class (50 vs. 46%; p < 0.0001) when using the median as a cutoff. However, after adjustment for age, the difference in body height between the two cohorts was no longer significant (p = 0.089). DFS and OS in the two upper height groups (≥170 cm) compared to the two lowest height groups (<160 cm) was not significantly different (5-year DFS: 84.7 vs. 83.0%; HR 0.91, 95% CI 0.73-1.13, p = 0.379; 5-year OS: 94.8 vs. 91.7%; HR 0.74, 95% CI 0.55-1.00, p = 0.051). The BMI of ABCSG patients was significantly higher than in the reference population (mean BMI 24.64 vs. 23.96; p < 0.0001). Conclusions: Our results do not confirm previous findings that greater body height is associated with a higher breast cancer risk and worse outcome.

Transferring MINDACT to Daily Routine: Implementation of the 70-Gene Signature in Luminal Early Breast Cancer - Results from a Prospective Registry of the Austrian Group Medical Tumor Therapy (AGMT).

Background: For hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative early breast cancer (EBC), adjuvant chemotherapy (ACT) is recommended in the case of high-risk features only. The MINDACT trial showed that patients with high clinical risk (CR) but low genomic risk (GR) defined by the 70-gene signature (MammaPrint®; 70-GS) did not benefit from ACT. In this registry, we investigated the frequency and feasibility of 70-GS and concurrent 80-gene subtyping (BluePrint®) use in HR-positive, HER2-negative EBC. Furthermore, we recorded the frequency of ACT recommendation and the adherence to it when the "MINDACT strategy" was used. Methods: This prospective registry included patients from 2 Austrian cancer centers. Similar to MINDACT, a modified version of Adjuvant!Online was used to determine CR, and 70-GC was used to determine GR in high-CR patients. ACT was recommended to patients with high CR and high GR. Results: Of 224 enrolled patients, 76 (33.9%) had high CR and 67 (88.2%) received genomic testing. Of those, 43 (64.2%) were classified as low and 24 (35.8%) as high GR, respectively. All 24 patients with high CR and GR (10.7% of all patients) received the recommendation for ACT, but ACT was started in only 15 patients (62.5%). The median time from surgery to the start of ACT was 45 days (range 32-68), and the median time from test decision to the test result was 15 days (range 9-56). Conclusion: We showed that the results of the MINDACT trial are reproducible in an Austrian population. Incorporating 70-GS into the daily clinical routine is feasible and mostly accepted by physicians for the guidance of treatment recommendations.

Persistence of ctDNA in Patients with Breast Cancer During Neoadjuvant Treatment Is a Significant Predictor of Poor Tumor Response.

PURPOSE: Accurate response assessment during neoadjuvant systemic treatment (NST) poses a clinical challenge. Therefore, a minimally invasive assessment of tumor response based on cell-free circulating tumor DNA (ctDNA) may be beneficial to guide treatment decisions. EXPERIMENTAL DESIGN: We profiled 93 genes in tissue from 193 patients with early breast cancer. Patient-specific assays were designed for 145 patients to track ctDNA during NST in plasma. ctDNA presence and levels were correlated with complete pathological response (pCR) and residual cancer burden (RCB) as well as clinicopathologic characteristics of the tumor to identify potential proxies for ctDNA release. RESULTS: At baseline, ctDNA could be detected in 63/145 (43.4%) patients and persisted in 25/63 (39.7%) patients at mid-therapy (MT) and 15/63 (23.8%) patients at the end of treatment. ctDNA detection at MT was significantly associated with higher RCB (OR = 0.062; 95% CI, 0.01-0.48; P = 0.0077). Of 31 patients with detectable ctDNA at MT, 30 patients (96.8%) were nonresponders (RCB II, n = 8; RCB III, n = 22) and only one patient responded to the treatment (RCB I). Considering all 145 patients with baseline (BL) plasma, none of the patients with RCB 0 and only 6.7% of patients with RCB I had ctDNA detectable at MT, whereas 30.6% and 29.6% of patients with RCB II/III, respectively, had a positive ctDNA result. CONCLUSIONS: Overall, our results demonstrate that the detection and persistence of ctDNA at MT may have the potential to negatively predict response to neoadjuvant treatment and identify patients who will not achieve pCR or be classified with RCB II/III.

Long-Term Outcomes of Adjuvant Denosumab in Breast Cancer.

BACKGROUND: Adjuvant aromatase inhibitors increase osteoporosis and fractures in patients with hormone receptor­positive breast cancer. We have previously reported outcomes of the ABCSG-18 (study 18 from the Austrian Breast & Colorectal Cancer Study Group) trial showing that adjuvant anti­receptor activator of nuclear factor-κB ligand denosumab treatment counteracts these adverse effects and may improve outcomes. We report here the final long-term outcomes. METHODS: ABCSG-18 is a prospective, double-blind, placebo-controlled, phase 3 trial in which 3425 postmenopausal patients with early hormone receptor­positive breast cancer receiving aromatase inhibitor therapy were randomly assigned in 58 trial centers to receive either denosumab 60 mg or placebo administered subcutaneously every 6 months. The primary end point was the time to first clinical fracture after randomization. Secondary disease outcome­related end points were disease-free survival (DFS), bone metastasis­free survival (BMFS), and overall survival (OS). RESULTS: For this final protocol-defined analysis, median follow-up is 8 years (interquartile range, 6 to 9.6 years). There were 309 versus 368 DFS events (hazard ratio, 0.83; 95% confidence interval [CI], 0.71 to 0.97) in the denosumab versus the placebo group, respectively, resulting in an absolute 9-year DFS benefit of 3.5 percentage points (79.4 vs. 75.9%). Adjuvant denosumab improved BMFS by 2.5 percentage points (88.9 vs. 86.4%; hazard ratio, 0.81; 95% CI, 0.65 to 1.00) and OS by 1.0 percentage point (90.9 vs. 89.9%; hazard ratio, 0.80; 95% CI, 0.64 to 1.01). No new toxicities for this dose of adjuvant denosumab were observed. CONCLUSIONS: DFS, BMFS, and OS continued to show benefit in this final long-term analysis of ABCSG-18. There were no new toxicities. (Funded by Amgen; ClinicalTrials.gov number, NCT00556374.)

Duration of Adjuvant Aromatase-Inhibitor Therapy in Postmenopausal Breast Cancer.

BACKGROUND: For postmenopausal women with hormone-receptor-positive breast cancer, the most effective duration for adjuvant therapy with an aromatase inhibitor remains unclear. METHODS: In this prospective, phase 3 trial, we randomly assigned postmenopausal women with hormone-receptor-positive breast cancer who had received 5 years of adjuvant endocrine therapy to receive the aromatase inhibitor anastrozole for an additional 2 years (2-year group, receiving a total of 7 years) or an additional 5 years (5-year group, receiving a total of 10 years). The primary end point was disease-free survival. The primary analysis included all the patients who were still participating in the trial and who had no recurrence 2 years after randomization (i.e., when treatment in the 2-year group had ended). Secondary end points were overall survival, contralateral breast cancer, second primary cancer, and clinical bone fracture. RESULTS: Among the 3484 women who were enrolled in the trial, 3208 remained in the trial without disease progression after the first 2 years of extended anastrozole treatment following randomization. Among these women, disease progression or death occurred in 335 women in each treatment group in the primary-analysis set at 8 years (hazard ratio, 0.99; 95% confidence interval [CI], 0.85 to 1.15; P = 0.90). No between-group differences occurred in most secondary end points, and subgroup analyses did not indicate differences in any particular subgroup. The risk of clinical bone fracture was higher in the 5-year group than in the 2-year group (hazard ratio, 1.35; 95% CI, 1.00 to 1.84). CONCLUSIONS: In postmenopausal women with hormone-receptor-positive breast cancer who had received 5 years of adjuvant endocrine therapy, extending hormone therapy by 5 years provided no benefit over a 2-year extension but was associated with a greater risk of bone fracture. (Funded by AstraZeneca and the Austrian Breast and Colorectal Cancer Study Group; ABCSG-16/SALSA ClinicalTrials.gov number, NCT00295620.).

Comparison of high tone therapy and transcutaneous electrical nerve stimulation therapy in chemotherapy-induced polyneuropathy.

INTRODUCTION: Chemotherapy-induced peripheral neuropathy (CIPN) is a worldwide concern in patients receiving neurotoxic agents for cancer therapy. High tone external muscle stimulation is a promising therapeutic approach to alleviate symptoms of CIPN. METHODS: This pilot study aims to investigate whether the application of home-based high-tone external muscle stimulation therapy (HTEMS) improves symptoms of CIPN. The trial is planned as a therapist- and assessor-blinded, 1:1 randomized controlled study. A total of 50 patients with chemotherapy-induced peripheral polyneuropathy will be included. All patients will perform therapy at home. Study participants will be allocated randomly to the HTEMS therapy (intervention group) or to the transcutaneous electrical nerve stimulation (TENS, control group), respectively, following a standardized therapy schedule. Compliance of participants can be verified by reading out the tool box. Outcomes will be evaluated at baseline and after 8 weeks of home-based therapy. The primary outcome includes improvement of CIPN according to the patient-reported EORTC QLQ-CIPN 20 questionnaire. Secondary outcomes are the patient-reported change in health-related quality of life and clinician-reported changes of vibration sensibility, tendon reflexes, temperature sensibility, perception of touch, and strength of the lower leg muscles. Further a safety- and process evaluation will be performed. DISCUSSION: This pilot RCT aims to evaluate the impact of home-based HTEMS as compared to TENS in CIPN. There is a need for an effective treatment for CIPN and the results of this study are expected to possibly identify a novel and effective treatment strategy in the future.

Poly-ligand profiling differentiates trastuzumab-treated breast cancer patients according to their outcomes.

Assessing the phenotypic diversity underlying tumour progression requires the identification of variations in the respective molecular interaction networks. Here we report proof-of-concept for a platform called poly-ligand profiling (PLP) that surveys these system states and distinguishes breast cancer patients who did or did not derive benefit from trastuzumab. We perform tissue-SELEX on breast cancer specimens to enrich single-stranded DNA (ssDNA) libraries that preferentially interact with molecular components associated with the two clinical phenotypes. Testing of independent sample sets verifies the ability of PLP to classify trastuzumab-treated patients according to their clinical outcomes with ROC-AUC of 0.78. Standard HER2 testing of the same patients gives a ROC-AUC of 0.47. Kaplan-Meier analysis reveals a median increase in benefit from trastuzumab-containing treatments of 300 days for PLP-positive compared to PLP-negative patients. If prospectively validated, PLP may increase success rates in precision oncology and clinical trials, thus improving both patient care and drug development.

Bone-targeted therapy in metastatic breast cancer - all well-established knowledge?

Bone-targeted therapies like bisphosphonates (zoledronic acid or pamidronate) or denosumab are recommended in all patients with metastatic breast cancer and bone metastases, whether they are symptomatic or not. The choice between these 2 different agents, however, remains open. In this review, we critically discuss the emerging evidence for direct anti-tumor activity of bone-targeting agents, the utility of bone turnover markers for treatment decision and efficacy prediction, as well as the safety and financial aspects of bisphosphonates and denosumab. Furthermore, we provide a possible therapeutic algorithm, and present new pharmacologic agents which are being investigated for the treatment of metastatic bone disease.

Neoadjuvant chemotherapy and targeted therapy in breast cancer: past, present, and future.

Traditionally, neoadjuvant treatment for breast cancer was preserved for locally advanced and inflammatory disease, converting an inoperable to a surgical resectable cancer. In recent years, neoadjuvant therapy has become an accepted treatment option also for lower tumor stages in order to increase the rate of breast conserving therapy and to reduce the extent of surgery. Furthermore, treatment response can be monitored, and therefore, patient compliance may be increased. Neoadjuvant trials, additionally, offer the opportunity to evaluate new treatment options in a faster way and with fewer patients than large adjuvant trials. Compared to the metastatic setting, the issue of acquired resistance and pretreatments, which may distort treatment efficacy, can be avoided. New trial designs like window-of-opportunity trials or postneoadjuvant trials provide the chance to identify tumor sensitivity or to overcome tumor resistance in early tumor stages. In particular, in HER2-positive breast cancer, the neoadjuvant approach yielded great successes. The dual HER2 blockade with trastuzumab and pertuzumab recently showed the highest pCR rates ever reported. Many new drugs are in clinical testing with the aim to further increase pCR rates. Whether this endpoint really represents a surrogate for long-term outcome is not answered yet and will be discussed in this review.

Capecitabine and Vinorelbine as an All-Oral Chemotherapy in HER2-Negative Locally Advanced and Metastatic Breast Cancer.

BACKGROUND: The oral formulation of vinorelbine together with capecitabine allows for an all-oral combination chemotherapy which promises to raise quality of life of patients with advanced breast cancer. PATIENTS AND METHODS: Patients with HER2-negative, locally advanced, inoperable or metastatic breast cancer were included in this prospective observational trial (treatment schedule: capecitabine 500 mg/m2 twice daily, days 1-14; vinorelbine 60 mg/m2, days 1+8; repeated in 3-week cycles). RESULTS: All 32 patients (median age 50 years) were evaluable for toxicity, and 30 patients for response. Twentyfour patients received therapy as first-line treatment, and 8 patients as beyond first-line treatment. Median time to progression was 8 months, and median overall survival was 32 months. Complete response was observed in 1 patient (3%), partial response in 10 patients (33%), and disease stabilization for more than 6 months (SD > 6) in 10 patients (33%). This results in an overall response rate (ORR) of 37% and a clinical benefit rate (ORR + SD > 6) of 70%. The only grade 3/4 toxicities were neutropenia (19%) and hand-foot syndrome (9%). CONCLUSIONS: The all-oral combination of capecitabine/vinorelbine at this schedule appears to be an effective, well-tolerated regimen for treatment of advanced breast cancer, and offers a promising alternative to single-agent capecitabine and vinorelbine as well as intravenous polychemotherapy.

Predicting for activity of second-line trastuzumab-based therapy in her2-positive advanced breast cancer.

BACKGROUND: In Her2-positive advanced breast cancer, the upfront use of trastuzumab is well established. Upon progression on first-line therapy, patients may be switched to lapatinib. Others however remain candidates for continued antibody treatment (treatment beyond progression). Here, we aimed to identify factors predicting for activity of second-line trastuzumab-based therapy. METHODS: Ninety-seven patients treated with > 1 line of trastuzumab-containing therapy were available for this analysis. Her2-status was determined by immunohistochemistry and re-analyzed by FISH if a score of 2+ was gained. Time to progression (TTP) on second-line therapy was defined as primary study endpoint. TTP and overall survival (OS) were estimated using the Kaplan-Meier product limit method. Multivariate analyses (Cox proportional hazards model, multinomial logistic regression) were applied in order to identify factors associated with TTP, response, OS, and incidence of brain metastases. p values < 0.05 were considered to indicate statistical significance. RESULTS: Median TTP on second-line trastuzumab-based therapy was 7 months (95% CI 5.74-8.26), and 8 months (95% CI 6.25-9.74) on first-line, respectively (n.s.). In the multivariate models, none of the clinical or histopthological features could reliably predict for activity of second-line trastuzumab-based treatment. OS was 43 months suggesting improved survival in patients treated with trastuzumab in multiple-lines. A significant deterioration of cardiac function was observed in three patients; 40.2% developed brain metastases while on second-line trastuzumab or thereafter. CONCLUSION: Trastuzumab beyond progression showed considerable activity. None of the variables investigated correlated with activity of second-line therapy. In order to predict for activity of second-line trastuzumab, it appears necessary to evaluate factors known to confer trastuzumab-resistance.

Trastuzumab and gemcitabine as salvage therapy in heavily pre-treated patients with metastatic breast cancer.

PURPOSE: In Her2-postive metastatic breast carcinoma, first-line trastuzumab-based therapy is well established; many centres continue antibody treatment beyond disease progression. In this trial, we evaluated the efficacy and safety of gemcitabine and trastuzumab after earlier exposure to anthracyclines, docetaxel and/or vinorelbine, and trastuzumab. METHODS: Twenty-nine consecutive patients were included as eligible. Patients received gemcitabine at a dose of 1,250 mg/m2 on day one and eight, every 21 days. Trastuzumab was administered in three-week cycles. Clinical benefit rate (CBR; CR + PR + SD > or = 6 months) was defined as primary endpoint. RESULTS: As of July 2007, all patients are evaluable for toxicity, and 26 for response. Earlier therapies consisted of trastuzumab (100%), anthracyclines (100%), vinorelbine (96.6%), docetaxel (72.4%), and capecitabine (72.4%). 19.2% of patients experienced PR, and SD > or = 6 months was observed in a further 26.9%, resulting in a CBR of 46.2%. Time to progression was median 3 months, and overall survival 17 months. Neutropenia (20.7%), thrombocytopenia (13.8%), and nausea (3.4%) were the only treatment-related adverse events that occurred with grade 3 or 4 intensity. Four patients (13.8%) developed brain metastases while on therapy. CONCLUSIONS: While CBR was low when compared to trastuzumab-based first-line therapy, it is higher than what would be expected from gemcitabine monotherapy in a similar setting. Together with the favourable toxicity profile, this regimen appears to be a safe and potentially effective salvage therapy option in a heavily pre-treated population.