Timing of exercise therapy when initiating adjuvant chemotherapy for breast cancer: a randomized trial.

AIMS: The most appropriate timing of exercise therapy to improve cardiorespiratory fitness (CRF) among patients initiating chemotherapy is not known. The effects of exercise therapy administered during, following, or during and following chemotherapy were examined in patients with breast cancer. METHODS AND RESULTS: Using a parallel-group randomized trial design, 158 inactive women with breast cancer initiating (neo)adjuvant chemotherapy were allocated to receive (1:1 ratio): usual care or one of three exercise regimens-concurrent (during chemotherapy only), sequential (after chemotherapy only), or concurrent and sequential (continuous) (n = 39/40 per group). Exercise consisted of treadmill walking three sessions/week, 20-50 min at 55%-100% of peak oxygen consumption (VO2peak) for ≈16 (concurrent, sequential) or ≈32 (continuous) consecutive weeks. VO2peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and ≈16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO2peak change between concurrent exercise and usual care during chemotherapy vs. VO2peak change between sequential exercise and usual care after chemotherapy [overall difference, -0.88 mL O2·kg-1·min-1; 95% confidence interval (CI): -3.36, 1.59, P = 0.48]. In secondary analysis, continuous exercise, approximately equal to twice the length of the other regimens, was well-tolerated and the only strategy associated with significant improvements in VO2peak from baseline to post-intervention (1.74 mL O2·kg-1·min-1, P < 0.001). CONCLUSION: There was no statistical difference in CRF improvement between concurrent vs. sequential exercise therapy relative to usual care in women with primary breast cancer. The promising tolerability and CRF benefit of ≈32 weeks of continuous exercise therapy warrant further evaluation in larger trials.

Effects of Exercise Therapy Dosing Schedule on Impaired Cardiorespiratory Fitness in Patients With Primary Breast Cancer: A Randomized Controlled Trial.

BACKGROUND: Current exercise guidelines for clinical populations recommend an exercise therapy (ET) prescription of fixed intensity (moderate), duration (40-50 minutes per session), and volume (120-160 min/wk). A critical overarching element of exercise programming that has received minimal attention is dose scheduling. We investigated the tolerability and efficacy of 2 exercise training dose regimens on cardiorespiratory fitness and patient-reported outcomes in patients with posttreatment primary breast cancer. METHODS: Using a parallel-group randomized trial, we randomly allocated 174 postmenopausal patients (2.8 years after adjuvant therapy) with impaired peak oxygen consumption (VO2peak) to 1 of 2 supervised exercise training interventions delivered with a standard linear (LET) (fixed dose intensity per session for 160 min/wk) or nonlinear (NLET) (variable dose intensity per session for ≈120 min/wk) schedule compared with a stretching attention control group for 16 consecutive weeks. Stretching was matched to exercise dosing arms on the basis of location, frequency, duration, and treatment length. The primary end point was change in VO2peak (mL O2·kg-1·min-1) from baseline to after intervention. Secondary end points were patient-reported outcomes, tolerability, and safety. RESULTS: No serious adverse events were observed. Mean attendance was 64%, 75%, and 80% for attention control, LET, and NLET, respectively. In intention-to-treat analysis, VO2peak increased 0.6±1.7 mL O2·kg-1·min-1 (P=0.05) and 0.8±1.8 mL O2·kg-1·min-1 (P=0.07) in LET and NLET, respectively, compared with attention control. Change in VO2peak ranged from -2.7 to 4.1 mL O2·kg-1·min-1 and from -3.6 to 5.1 mL O2·kg-1·min-1 in LET and NLET, respectively. Approximately 40% of patients in both exercise dosing regimens were classified as VO2peak responders (ie, Δ ≥1.32 mL O2·kg-1·min-1). NLET improved all patient-reported outcomes compared with attention control. CONCLUSIONS: Short-term exercise training, independently of dosing schedule, is associated with modest improvements in cardiorespiratory fitness in patients previously treated for early-stage breast cancer. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01186367.

Long-term follow-up assessment of cardiac safety in SAFE-HEaRt, a clinical trial evaluating the use of HER2-targeted therapies in patients with breast cancer and compromised heart function.

PURPOSE: HER2-targeted therapies are associated with cardiotoxicity which is usually asymptomatic and reversible. We report the updated cardiac safety assessment of patients with compromised heart function receiving HER2-targeted therapy for breast cancer, enrolled in the SAFE-HEaRt trial, at a median follow-up of 3.5 years. METHODS: Thirty patients with stage I-IV HER2-positive breast cancer receiving trastuzumab with or without pertuzumab, or ado-trastuzumab emtansine (T-DM1), with asymptomatic LVEF (left ventricular ejection fraction) 40-49%, were started on cardioprotective medications, with the primary endpoint being completion of HER2-targeted therapy without cardiac events (CE) or protocol-defined asymptomatic worsening of LVEF. IRB-approved follow-up assessment included 23 patients. RESULTS: Median follow-up as of June 2020 is 42 months. The study met its primary endpoint with 27 patients (90%) completing their HER2-targeted therapies without cardiac issues. Of the 23 evaluable patients at long-term f/u, 14 had early stage breast cancer, and 9 had metastatic disease, 8 of whom remained on HER2-targeted therapies. One patient developed symptomatic heart failure with no change in LVEF. There were no cardiac deaths. The mean LVEF improved to 52.1% from 44.9% at study baseline, including patients who remained on HER2-targeted therapy, and those who received prior anthracyclines. CONCLUSIONS: Long-term follow-up of the SAFE-HEaRt study continues to provide safety data of HER2-targeted therapy use in patients with compromised heart function. The late development of cardiac dysfunction is uncommon and continued multi-disciplinary oncologic and cardiac care of patients is vital for improved patient outcomes.

Cardiac outcomes of trastuzumab therapy in patients with HER2-positive breast cancer and reduced left ventricular ejection fraction.

PURPOSE: Asymptomatic decline in left ventricular ejection fraction (LVEF) or heart failure (HF) occurs in up to 25% of patients treated with trastuzumab and can result in incomplete breast cancer therapy. The cardiac safety of continuing trastuzumab in patients with asymptomatic LVEF decline is unknown. We report the cardiac outcomes of patients treated with trastuzumab after a significant asymptomatic LVEF decline. METHODS: Patients with HER2-positive breast cancer and asymptomatic LVEF decline to < 50% during trastuzumab were identified from an institutional echocardiogram database. Patients who received trastuzumab with a LVEF < 50% were classified as the continued group, whereas patients who had trastuzumab held until LVEF improved to ≥ 50% or who had trastuzumab permanently discontinued were classified as the interrupted group. Cardiac events were defined as HF (New York Heart Association class III-IV) or cardiovascular death. RESULTS: Sixty patients were included; the median age was 54 years. In 23 patients who continued trastuzumab, 14 (61%) tolerated trastuzumab without a cardiac event, 6 (26%) developed worsening LVEF (range 25-42%) leading to trastuzumab discontinuation, and three (13%) developed a cardiac event (1 HF, 2 possible/probable cardiovascular deaths). In 37 patients with interrupted trastuzumab, 15 (41%) were re-challenged with trastuzumab after LVEF improved to > 50%, 21 (57%) were not re-challenged, and one (3%) developed HF. More patients in the continued trastuzumab group had metastatic disease (39% vs. 5%, p = 0.002). The final LVEF after median follow-up of 633 days was similar between patients with trastuzumab continuation versus interruption (54% vs. 56%, p = 0.29). CONCLUSION: Continuation of trastuzumab after an asymptomatic LVEF decline to < 50% in patients who are expected to benefit from additional anti-HER2 therapy is a promising approach that warrants further investigation.

Cardiotoxicity of HER2-targeted therapies.

PURPOSE OF REVIEW: Cardiotoxicity is a well recognized adverse effect of human epidermal growth factor receptor 2 (HER2)-targeted therapies. The goal of this review is to highlight recent studies that have advanced our knowledge of the diagnosis, prevention, and management of cardiotoxicity associated with HER2-targeted agents. RECENT FINDINGS: Several clinical risk factors for cardiotoxicity associated with HER2-targeted therapies have been identified including age, low-baseline left ventricular ejection fraction, and treatment with anthracyclines; however, these remain insufficient to identify all patients at risk for cardiotoxicity. Routine cardiac monitoring remains the standard for cardiotoxicity surveillance, although the optimal frequency and modality of monitoring remains uncertain. Global longitudinal strain, T1/T2 weighted CMR imaging protocols, and circulating biomarkers can detect early signs of cardiotoxicity, but studies are needed to investigate whether use of these markers in clinical practice improves patient outcomes. Cardioprotective medications (e.g. beta-blockers or ACE-inhibitors) may be of benefit to patients at increased risk for cardiotoxicity from HER2-taregeted therapies, particularly those who are treated with an anthracycline-containing regimen. SUMMARY: Improved risk stratification of patients during HER2-targeted therapy and effective prevention and management strategies for cardiotoxicity are needed to enhance the value of longitudinal cardiac monitoring and increase cardiac safety so that optimal breast cancer treatment can be delivered.

Cardiotoxicity of Contemporary Breast Cancer Treatments.

OPINION STATEMENT: Treatment-related cardiotoxicity remains a significant concern for breast cancer patients undergoing cancer treatment and extends into the survivorship period, with adverse cardiovascular (CV) outcomes further compounded by the presence of pre-existing CV disease or traditional CV risk factors. Awareness of the cardiotoxicity profiles of contemporary breast cancer treatments and optimization of CV risk factors are crucial in mitigating cardiotoxicity risk. Assessment of patient- and treatment-specific risk with appropriate CV surveillance is another key component of care. Mismatch between baseline cardiotoxicity risk and intensity of cardiotoxicity surveillance can lead to unnecessary downstream testing, increased healthcare expenditure, and interruption or discontinuation of potentially life-saving treatment. Efforts to identify early imaging and/or circulating biomarkers of cardiotoxicity and develop effective management strategies are needed to optimize the CV and cancer outcomes of breast cancer survivors.

Cardiac Safety of Dual Anti-HER2 Therapy in the Neoadjuvant Setting for Treatment of HER2-Positive Breast Cancer.

BACKGROUND: Trastuzumab and pertuzumab are approved for the neoadjuvant treatment of human epidermal growth receptor 2 (HER2)-positive breast cancer, but cardiac safety data is limited. We report the cardiac safety of dose-dense doxorubicin and cyclophosphamide (AC) followed by paclitaxel, trastuzumab, and pertuzumab (THP) in the neoadjuvant setting followed by adjuvant trastuzumab-based therapy. METHODS: Fifty-seven patients treated with neoadjuvant dose-dense AC-THP followed by adjuvant trastuzumab-based therapy between September 1, 2013, and March 1, 2015, were identified. The primary outcome was cardiac event rate, defined by heart failure (New York Heart Association [NYHA] class III/IV) or cardiac death. Patients underwent left ventricular ejection fraction (LVEF) monitoring at baseline, after AC, and serially during 1 year of anti-HER2 therapy. RESULTS: The median age was 46 years (range 26-68). Two (3.5%) patients developed NYHA class III/IV heart failure 5 and 9 months after initiation of trastuzumab-based therapy, leading to permanent discontinuation of anti-HER2 treatment. Seven (12.3%) patients developed a significant LVEF decline (without NYHA class III/IV symptoms). The median LVEF was 65% (range 55%-75%) at baseline and 64% (range 53%-72%) after AC, and decreased to 60% (range 35%-70%), 60% (range 23%-73%), 61% (range 25%-73%), and 58% (range 28%-66%) after 3, 6, 9, and 12 months (± 6 weeks) of trastuzumab-based therapy. CONCLUSION: The incidence of NYHA class III/IV heart failure after neoadjuvant AC-THP (followed by adjuvant trastuzumab-based therapy) is comparable to rates reported in trials of sequential doxorubicin and trastuzumab. Our findings do not suggest an increased risk of cardiotoxicity from trastuzumab plus pertuzumab following a doxorubicin-based regimen. IMPLICATIONS FOR PRACTICE: Dual anti-human epidermal growth receptor 2 (HER2) therapy with trastuzumab and pertuzumab combined with standard chemotherapy has received accelerated approval for the neoadjuvant treatment of stage II-III HER2-positive breast cancer. Cardiac safety data for trastuzumab and pertuzumab in this setting are limited to clinical trials that utilized epirubicin-based chemotherapy. Formalized investigations into the cardiac safety of trastuzumab and pertuzumab with doxorubicin- (rather than epirubicin) based regimens are important because these regimens are widely used for the adjuvant and neoadjuvant treatment of breast cancer. The known role of HER2 signaling in the physiological adaptive responses of the heart provides further rationale for study on the potential cardiotoxicity of dual anti-HER2 blockade. Findings from this retrospective study provide favorable preliminary data on the cardiac safety of trastuzumab and pertuzumab in combination with a regimen of neoadjuvant doxorubicin and cyclophosphamide followed by paclitaxel, one of the preferred breast cancer treatment regimens, according to the National Comprehensive Cancer Network.

Pathologic Complete Response with Neoadjuvant Doxorubicin and Cyclophosphamide Followed by Paclitaxel with Trastuzumab and Pertuzumab in Patients with HER2-Positive Early Stage Breast Cancer: A Single Center Experience.

OBJECTIVES: Trastuzumab (H) and pertuzumab (P) with standard chemotherapy is approved for use in the neoadjuvant setting for human epidermal growth receptor 2 -positive patients. A retrospective analysis was performed of patients treated with dose-dense (dd) doxorubicin and cyclophosphamide (AC) followed by paclitaxel (T), trastuzumab, and pertuzumab (THP) in the neoadjuvant setting. Here, the pathologic complete response (pCR) rates are reported. METHODS: An electronic medical record review was conducted of patients treated with HP-based therapy in the neoadjuvant setting from September 1, 2013, to March 1, 2015. Data on patient demographics, stage of breast cancer, pathology reports, surgical data, and information on systemic therapy were collected. The pCR was defined as total (tpCR, ypT0/is ypN0), German Breast Group (GBG) pCR (ypT0 ypN0), breast pCR (bpCR) with in situ disease (ypT0/is) and without in situ disease (ypT0), and explored axillary pCR (ypN0). RESULTS: Charts from 66 patients were reviewed, and 57 patients were evaluable for pCR. Median age was 46 years (range 26-68 years). Median tumor size was 4 cm. Of 57 patients, 53 (93%) had operable breast cancer (T1-3, N0-1, M0). Three patients (5.3%) had locally advanced disease (T2-3, N2-3, M0 or T4a-c, any N, M0), and 1 (1.7%) had inflammatory breast cancer (T4d, any N, M0). Overall, 44 (77%) and 13 (23%) had hormone receptor (HR)-positive and negative diseases, respectively. Median numbers of cycles of neoadjuvant treatment were as follows: AC (4, range 1-4), T (4, range 1-4), trastuzumab (6, range 3-8), and pertuzumab (6, range 2-8). In these 57 patients, the rates of tpCR and bpCR with in situ disease were demonstrated in 41/57 (72%) patients, and the rates of GBG pCR and bpCR without in situ disease were found in 30/57 (53%) patients. Of 26 patients with biopsy-proven lymph nodal involvement, axillary pCR occurred in 22 (85%) patients. CONCLUSION: At a single center, the tpCR and GBG pCR rates of dd AC followed by THP are high at 72% and 53%, respectively. The Oncologist 2017;22:139-143Implications for Practice: This is the first study describing the role of doxorubicin and cyclophosphamide followed by paclitaxel and dual anti-HER2 therapy with trastuzumab and pertuzumab (ACTHP) in patients with early stage HER2-positive breast cancer. Total (breast + lymph node) pathological complete remission (pCR) remission (ypT0/is ypN0) and German Breast Group pCR rates (ypT0/ ypN0) were high at 72% and 53%, respectively, with the ACTHP regimen. Rate of axillary clearance in patients with known axillary involvement was high at 85%, which may translate into less extensive axillary surgeries in this subset in the future.

Cardiac safety of non-anthracycline trastuzumab-based therapy for HER2-positive breast cancer.

PURPOSE: Trastuzumab improves overall survival for women with HER2-positive breast cancer but is associated with cardiotoxicity, especially when administered after anthracyclines. Use of non-anthracycline trastuzumab-based regimens is rising, particularly for patients with low-risk disease or with multiple cardiovascular risk factors. We performed a single-center retrospective cohort study to assess the cardiac safety of trastuzumab without anthracyclines outside of a clinical trial setting. METHODS: A retrospective chart review was conducted of patients with HER2-positive early-stage breast cancer receiving non-anthracycline trastuzumab-based therapy between January 2010 and June 2014. Cardiovascular risk factors, left ventricular ejection fraction (LVEF), and treatment interruption data were collected. The primary outcome was a cardiac event (CE), defined by New York Heart Association class III or IV heart failure or cardiac death. The secondary outcome was a significant asymptomatic decline of LVEF (>10% to <55% or >16% from baseline). RESULTS: A total of 165 patients were identified with a median age of 59 years (range 32-85 years). Seventy (42%) had hypertension, 52 (32%) had hyperlipidemia, 29 (18%) had diabetes, and 5 (3%) had coronary artery disease. All patients had a LVEF >50% (median 67%; range 50-80%) at baseline. Two (1.2%) patients with multiple cardiovascular risk factors developed a CE. After discontinuation of trastuzumab, both patients had recovery of LVEF to >50% and resolution of heart failure symptoms. Ten (6.1%) patients developed significant asymptomatic LVEF decline during trastuzumab therapy. CONCLUSIONS: The overall incidence of symptomatic heart failure and asymptomatic LVEF decline among patients receiving trastuzumab without anthracyclines remains low. These findings suggest that less intensive cardiac monitoring may be appropriate during trastuzumab therapy without anthracyclines.

Cardiac Safety of Paclitaxel Plus Trastuzumab and Pertuzumab in Patients With HER2-Positive Metastatic Breast Cancer.

INTRODUCTION: Myocardial strain imaging and blood biomarkers have been proposed as adjuncts to left ventricular ejection fraction (LVEF) monitoring for the early detection of cardiotoxicity during cancer therapy. We report the results of a preplanned cardiac safety analysis of global longitudinal strain (GLS), and troponin-I (TnI) and brain natriuretic peptide (BNP) levels in the phase II study of paclitaxel, trastuzumab, and pertuzumab (THP) for metastatic HER2-positive breast cancer. PATIENTS AND METHODS: Patients with 0-1 lines of prior therapy were treated with weekly paclitaxel (80 mg/m(2)) plus trastuzumab (8 mg/kg loading dose followed by 6 mg/kg) and pertuzumab (840 mg loading dose followed by 420 mg) every 3 weeks. Exploratory endpoints were GLS measured with speckle-tracking echocardiography every 3 months and TnI and BNP levels measured every 6 weeks (immediately pre- and postchemotherapy infusion) at 6 time points. RESULTS: Sixty-seven of 69 enrolled patients were treated with THP: 19 (28%) had hypertension, 8 (12%) had diabetes, 11 (16%) had hyperlipidemia, and 26 (38%) had smoking history. After a median follow-up of 21 months (range: 3-38 months), no patients developed symptomatic heart failure. Two patients (3.0%) experienced asymptomatic LVEF decline (grade 2). The mean GLS (±SD) was 19% ± 2% (baseline), 19% ± 2% (month 6), and 19% ± 3% (month 12). Detectable TnI (>0.06 ng/mL) and elevated BNP (>100 pg/mL) levels were observed in 3 (4.3%) and 2 (3.0%) patients, respectively, but were not associated with LVEF decline. CONCLUSION: The absence of any significant changes in GLS and cardiac biomarkers (TnI and BNP) further support the cardiac safety of THP in patients with metastatic HER2-positive breast cancer. IMPLICATIONS FOR PRACTICE: Dual anti-HER2 therapy with trastuzumab and pertuzumab in combination with taxane-based chemotherapy improves overall survival in patients with metastatic HER2-positive breast cancer. There is a critical need to investigate the potential cardiotoxicity of dual anti-HER2 blockade, given the importance of HER2 signaling in cardiac homeostasis and stress response. Global longitudinal strain and cardiac biomarkers have been proposed as adjuncts to left ventricular ejection fraction for the early detection of cardiotoxicity. In this phase II study of combination trastuzumab and pertuzumab with paclitaxel, no clinically significant change was observed in global longitudinal strain or cardiac biomarkers. These results further support the cardiac safety of dual anti-HER2 blockade previously reported in the CLEOPATRA study. The findings in the current study also call into question the role of intensive cardiac monitoring among patients treated with anti-HER2 therapy in the absence of anthracyclines. Less frequent cardiac assessments could lead to a reduction in unnecessary treatment interruption and is an important consideration given the rise in medical expenditures, but this requires further investigation.

Continuous Trastuzumab Therapy in Breast Cancer Patients With Asymptomatic Left Ventricular Dysfunction.

BACKGROUND: Adjuvant trastuzumab is a highly effective targeted treatment that improves survival for patients with HER2-positive breast cancer. However, trastuzumab interruption is recommended for patients who develop treatment-induced cardiotoxicity (i.e., decline in left ventricular ejection fraction [LVEF], with or without symptoms) and can lead to an incomplete course of treatment. We studied the cardiac safety of continuous trastuzumab therapy among patients with asymptomatic declines in LVEF. METHODS: We retrospectively evaluated patients with HER2-positive breast cancer treated with adjuvant trastuzumab at our institution between 2005 and 2010. Treatment-induced cardiotoxicity was defined by an absolute decrease in LVEF of ≥10% to below 55% or an absolute decrease of ≥16%. Logistic regression was used to determine the association between candidate risk factors and treatment-induced cardiotoxicity. RESULTS: Among 573 patients, 92 (16%) developed treatment-induced cardiotoxicity. Trastuzumab was continued without interruption in 31 of 92 patients with treatment-induced cardiotoxicity­all were asymptomatic with LVEF of ≥50% at cardiotoxicity diagnosis with median LVEF of 53% (range, 50%-63%), and none developed heart failure during follow-up. Risk factors associated with treatment-induced cardiotoxicity included age (p = .011), anthracycline chemotherapy (p = .002), and lower pretrastuzumab LVEF (p < .001). CONCLUSION: Among patients who develop asymptomatic treatment-induced cardiotoxicity with LVEF of ≥50%, continuous trastuzumab therapy appears to be safe.

Trastuzumab interruption and treatment-induced cardiotoxicity in early HER2-positive breast cancer.

Trastuzumab improves outcomes among patients with HER2-positive breast cancer but is associated with a risk of treatment-induced cardiotoxicity (TIC). It is unclear how frequently TIC leads to trastuzumab interruption outside of prospective trials, and how TIC is managed in clinical practice. Patients with HER2-postive breast cancer receiving adjuvant trastuzumab from 2005 to 2010 were identified (n = 608). We evaluated the incidence, risk factors, and management of trastuzumab interruption due to TIC. In total, 488 (80 %) patients were treated with anthracycline prior to trastuzumab. Trastuzumab was interrupted in 108 (18 %) patients. Cumulative trastuzumab dose was lower in the interrupted group (median 86 vs. 108 mg/kg, p < 0.0001). The most common reason for interruption was TIC (66 of 108 patients): 20 had symptomatic heart failure and 46 had asymptomatic left ventricular ejection fraction (LVEF) decline. Patients with trastuzumab interruption for TIC were older (54 vs. 50 years, p = 0.014) with lower LVEF before anthracycline (63 vs. 67 %, p < 0.0001) and trastuzumab (62 vs. 67 %, p < 0.0001) therapy. Mean LVEF at baseline, TIC diagnosis, and follow-up after trastuzumab interruption was 63, 45, and 55 %, respectively. Thirty-three of 66 patients with TIC were re-challenged with trastuzumab, and five patients had recurrent LVEF decline. In clinical practice, trastuzumab interruption is common and most often due to TIC, with most patients receiving anthracycline prior to trastuzumab. Cardiac dysfunction improves after trastuzumab interruption but may not fully recover to baseline. Strategies to minimize cardiotoxicity and treatment interruption should be investigated to prevent persistent left ventricular dysfunction in affected patients.

Cardiomyopathy associated with cancer therapy.

Chemotherapy-associated cardiomyopathy is a well known cardiotoxicity of contemporary cancer treatment and a cause of increasing concern for both cardiologists and oncologists. As cancer outcomes improve, cardiovascular disease has become a leading cause of morbidity and mortality among cancer survivors. Asymptomatic or symptomatic left ventricular systolic dysfunction in the setting of cardiotoxic chemotherapy is an important entity to recognize. Early diagnosis of cardiac injury through the use of novel blood-based biomarkers or noninvasive imaging modalities may allow for the initiation of cardioprotective medications or modification of chemotherapy regimen to minimize or prevent further damage. Several clinical trials are currently underway to determine the efficacy of cardioprotective medications for the prevention of chemotherapy-associated cardiomyopathy. Implementing a strategy that includes both early detection and prevention of cardiotoxicity will likely have a significant impact on the overall prognosis of cancer survivors. Continued coordination of care between cardiologists and oncologists remains critical to maximizing the oncologic benefit of cancer therapy while minimizing any early or late cardiovascular effects.

Mechanisms of Exercise Intolerance Across the Breast Cancer Continuum: A Pooled Analysis of Individual Patient Data.

PURPOSE: The purpose of this study is to evaluate the prevalence of abnormal cardiopulmonary responses to exercise and pathophysiological mechanism(s) underpinning exercise intolerance across the continuum of breast cancer (BC) care from diagnosis to metastatic disease. METHODS: Individual participant data from four randomized trials spanning the BC continuum ([1] prechemotherapy [n = 146], [2] immediately postchemotherapy [n = 48], [3] survivorship [n = 138], and [4] metastatic [n = 47]) were pooled and compared with women at high-risk of BC (BC risk; n = 64). Identical treadmill-based peak cardiopulmonary exercise testing protocols evaluated exercise intolerance (peak oxygen consumption; V̇O2peak) and other resting, submaximal, and peak cardiopulmonary responses. The prevalence of 12 abnormal exercise responses was evaluated. Graphical plots of exercise responses were used to identify oxygen delivery and/or uptake mechanisms contributing to exercise intolerance. Unsupervised, hierarchical cluster analysis was conducted to explore exercise response phenogroups. RESULTS: Mean V̇O2peak was 2.78 ml O2.kg-1·min-1 (95% confidence interval [CI], -3.94, -1.62 mL O2.kg-1·min-1; P < 0.001) lower in the pooled BC cohort (52 ± 11 yr) than BC risk (55 ± 10 yr). Compared with BC risk, the pooled BC cohort had a 2.5-fold increased risk of any abnormal cardiopulmonary response (odds ratio, 2.5; 95% confidence interval, 1.2, 5.3; P = 0.014). Distinct exercise responses in BC reflected impaired oxygen delivery and uptake relative to control, although considerable inter-individual heterogeneity within cohorts was observed. In unsupervised, hierarchical cluster analysis, six phenogroups were identified with marked differences in cardiopulmonary response patterns and unique clinical characteristics. CONCLUSIONS: Abnormal cardiopulmonary response to exercise is common in BC and is related to impairments in oxygen delivery and uptake. The identification of exercise response phenogroups could help improve cardiovascular risk stratification and guide investigation of targeted exercise interventions.

Rationale and design of a cardiac safety study for reduced cardiotoxicity surveillance during HER2-targeted therapy.

BACKGROUND: Echocardiograms are recommended every 3 months in patients receiving human epidermal growth factor 2 (HER2)-targeted therapy for surveillance of left ventricular ejection fraction (LVEF). Efforts to tailor treatment for HER2-positive breast cancer have led to greater use of non-anthracycline regimens that are associated with lower cardiotoxicity risk, raising into question the need for frequent cardiotoxicity surveillance for these patients. This study seeks to evaluate whether less frequent cardiotoxicity surveillance (every 6 months) is safe for patients receiving a non-anthracycline HER2-targeted treatment regimen. METHODS/DESIGN: We will enroll 190 women with histologically confirmed HER2-positive breast cancer scheduled to receive a non-anthracycline HER2-targeted treatment regimen for a minimum of 12 months. All participants will undergo echocardiograms before and 6-, 12-, and 18-months after initiation of HER2-targeted treatment. The primary composite outcome is symptomatic heart failure (New York Heart Association class III or IV) or death from cardiovascular causes. Secondary outcomes include: 1) echocardiographic indices of left ventricular systolic function; 2) incidence of cardiotoxicity, defined by a ≥ 10% absolute reduction in left ventricular ejection fraction (LVEF) from baseline to < 53%; and 3) incidence of early interruption of HER2-targeted therapy. CONCLUSIONS: To our knowledge, this will be the first prospective study of a risk-based approach to cardiotoxicity surveillance. We expect findings from this study will inform the development of updated clinical practice guidelines to improve cardiotoxicity surveillance practices during HER2-positive breast cancer treatment. TRIAL REGISTRATION: The trial was registered in the ClinicalTrials.gov registry (identifier NCT03983382) on June 12, 2019.

Association of Circulating Cardiomyocyte Cell-Free DNA With Cancer Therapy-Related Cardiac Dysfunction in Patients Undergoing Treatment for ERBB2-Positive Breast Cancer.

Importance: Cancer therapy-related cardiac dysfunction (CTRCD) is a potentially serious cardiotoxicity of treatments for ERBB2-positive breast cancer (formerly HER2). Identifying early biomarkers of cardiotoxicity could facilitate an individualized approach to cardiac surveillance and early pharmacologic intervention. Circulating cell-free DNA (cfDNA) of cardiomyocyte origin is present during acute cardiac injury but has not been established as a biomarker of CTRCD. Objective: To determine whether circulating cardiomyocyte cfDNA is associated with CTRCD in patients with ERBB2-positive breast cancer treated with anthracyclines and ERBB2-targeted therapy. Design, Setting, and Participants: A prospective cohort of 80 patients with ERBB2-positive breast cancer enrolled at an academic cancer center between July 2014 and April 2016 underwent echocardiography and blood collection at baseline, after receiving anthracyclines, and at 3 months and 6 months of ERBB2-targeted therapy. Participants were treated with doxorubicin-based chemotherapy followed by trastuzumab (+/- pertuzumab). The current biomarker study includes participants with sufficient biospecimen available for analysis after anthracycline therapy. Circulating cardiomyocyte-specific cfDNA was quantified by a methylation-specific droplet digital polymerase chain reaction assay. Data for this biomarker study were collected and analyzed from June 2021 through April 2022. Main Outcomes and Measures: The outcome of interest was 1-year CTRCD, defined by symptomatic heart failure or an asymptomatic decline in left ventricular ejection fraction (≥10% from baseline to less than lower limit of normal or ≥16%). Values for cardiomyocyte cfDNA and high-sensitivity cardiac troponin I (hs-cTnI) measured after patients completed treatment with anthracyclines were compared between patients who later developed CTRCD vs patients who did not using the Wilcoxon rank sum test, and the association of post-anthracycline cardiomyocyte cfDNA level with CTRCD was estimated using logistic regression. Results: Of 71 patients included in this study, median (IQR) age was 50 (44-58) years, all were treated with dose-dense doxorubicin, and 48 patients underwent breast radiotherapy. Ten of 71 patients (14%) in this analysis developed CTRCD. The level of cardiomyocyte cfDNA at the post-anthracycline time point was higher in patients who subsequently developed CTRCD (median, 30.5 copies/mL; IQR, 24-46) than those who did not (median, 7 copies/mL; IQR, 2-22; P = .004). Higher cardiomyocyte cfDNA level after completion of anthracycline chemotherapy was associated with risk of CTRCD (hazard ratio, 1.02 per 1-copy/mL increase; 95% CI, 1.00-1.03; P = .046). Conclusions and Relevance: This study found that higher cardiomyocyte cfDNA level after completion of anthracycline chemotherapy was associated with risk of CTRCD. Cardiomyocyte cfDNA quantification shows promise as a predictive biomarker to refine risk stratification for CTRCD among patients with breast cancer receiving cardiotoxic cancer therapy, and its use warrants further validation. Trial Registration: ClinicalTrials.gov Identifier: NCT02177175.