Assessment of left ventricular diastolic function during trastuzumab treatment in patients with HER2-positive breast cancer

HER2-Targeted Therapy-From Pathophysiology to Clinical Manifestation: A Narrative Review

Trastuzumab is the primary treatment for all stages of HER2-overexpressing breast cancer in patients. Though discovered over 20 years ago, trastuzumab-induced cardiotoxicity (TIC) remains a research topic in cardio-oncology. This review explores the pathophysiological basis of TIC and its clinical manifestations. Their understanding is paramount for early detection and cardioprotective treatment. Trastuzumab renders cardiomyocytes susceptible by inhibiting the cardioprotective NRG-1/HER2/HER4 signaling pathway. The drug acts on HER2-receptor-expressing cardiomyocytes, endothelium, and cardiac progenitor cells (see the Graphical Abstract). The activation of immune cells, fibroblasts, inflammation, and neurohormonal systems all contribute to the evolution of TIC. A substantial amount of research demonstrates that trastuzumab induces overt and subclinical left ventricular (LV) systolic failure. Data suggest the development of right ventricular damage, LV diastolic dysfunction, and heart failure with preserved ejection fraction. Further research is needed to define a chronological sequence of cardiac impairments to guide the proper timing of cardioprotection implementation.

New Insights in the Era of Clinical Biomarkers as Potential Predictors of Systemic Therapy-Induced Cardiotoxicity in Women with Breast Cancer: A Systematic Review

Cardiotoxicity induced by breast cancer therapies is a potentially serious complication associated with the use of various breast cancer therapies. Prediction and better management of cardiotoxicity in patients receiving chemotherapy is of critical importance. However, the management of cancer therapy-related cardiac dysfunction (CTRCD) lacks clinical evidence and is based on limited clinical studies.

AIM

To provide an overview of existing and potentially novel biomarkers that possess a promising predictive value for the early and late onset of CTRCD in the clinical setting.

METHODS

A systematic review of published studies searching for promising biomarkers for the prediction of CTRCD in patients with breast cancer was undertaken according to PRISMA guidelines. A search strategy was performed using PubMed, Google Scholar, and Scopus for the period 2013-2023. All subjects were >18 years old, diagnosed with breast cancer, and received breast cancer therapies.

RESULTS

The most promising biomarkers that can be used for the development of an alternative risk cardiac stratification plan for the prediction and/or early detection of CTRCD in patients with breast cancer were identified.

CONCLUSIONS

We highlighted the new insights associated with the use of currently available biomarkers as a standard of care for the management of CTRCD and identified potentially novel clinical biomarkers that could be further investigated as promising predictors of CTRCD.

Pediatric malignancies: Is the prechemotherapy left ventricular function normal?

PURPOSE

We compared the left ventricular (LV) systolic function in children with cancer before initiation of chemotherapy with matched controls using speckle tracking echocardiography.

METHODS AND RESULTS

In this retrospective study, we analyzed the echocardiograms of 89 cancer patients before the initiation of chemotherapy and 82 age- (8.4 ± 5.2 vs. 8.9 ± 3.9 years, P = .4) and gender-matched (64% vs. 67%, males, P = .4) healthy controls. Peak systolic LV longitudinal strain (LS) was significantly lower in cancer patients in apical two (-19.8 ± 3.0 vs. -23.5 ± 4.0, P < .001), three (-19.4 ± 3.2 vs. -23.4 ± 4.0, P < .001), and four-chamber views (-19.7 ± 3.4 vs. -22.5 ± 3.0, P < .001) compared to controls, as was global longitudinal strain (GLS) (-19.8 ± 2.7 vs. -23.4 ± 3.2, P < .001). The prechemotherapy group also had a higher E/e' ratio compared to controls at the septal (9.3 ± 3.9 vs. 7.9 ± 1.7, P = .005) and lateral annulus (7.9 ± 3.3 vs. 5.9 ± 1.4, P < .001) of the mitral valve. The LV ejection fraction was lower in cancer patients compared to controls (63.5 ± 4.9 vs. 66.8 ± 4.1, P < .001), although still within normal limits. There were no differences in LV myocardial performance index (0.30 ± 0.05 vs. 0.30 ± 0.09, P < .65) and shortening fraction (35.8 ± 5.2 vs. 36.1 ± 6.1, P < 0.75) between the two groups. Subgroup analysis showed no difference in LV GLS between patients with solid tumors (n = 56) and blood cancers (n = 33) (GLS -19.2 ± 2.9 vs. 19.5 ± 2.4, P > 0.05).

CONCLUSION

Our data demonstrating abnormalities in LV GLS in pediatric cancer patients even prior to initiation of chemotherapy are novel and perplexing. Further longitudinal follow-up is required to assess the implications of this abnormal LV function in these patients.

Serial Measurements of Left Ventricular Systolic and Diastolic Function by Cardiac Magnetic Resonance Imaging in Patients with Early Stage Breast Cancer on Trastuzumab

Our aim was to evaluate the temporal changes in left ventricular (LV) diastolic filling in relation to other LV parameters using cardiac MRI (CMR) in patients with HER2 positive breast cancer receiving trastuzumab therapy. Fourty-one women with early stage HER2+ breast cancer underwent serial CMR (baseline, 6, 12, and 18 months) after initiation of trastuzumab therapy. A single, blinded observer measured LV parameters on de-identified CMRs in random order. Linear mixed models were used to investigate temporal changes. Compared to baseline, there were significant decreases in systolic function as measured by both left ventricular ejection fraction (LVEF) (p <0.001 at 6 and 12 months) and peak ejection rate corrected for end-diastolic volume (PER/LVEDV) (p = 0.008 at 6 months, p = 0.01 at 12 months). However, these differences were no longer significant at 18 months. In contrast, significant reductions in diastolic function as measured by LV peak filling rate corrected for end-diastolic volume (PFR/LVEDV) were observed at 6 months (p = 0.012), 12 months (p = 0.031), and up to 18 months (p = 0.034). There were no significant temporal changes in the time to peak filling rate corrected for cardiac cycle (TPF/RR). The reduction in PFR/LVEDV at 18 months was no longer significant when corrected for heart rate. In conclusion, there were significant subclinical deleterious effects on both LV systolic and diastolic function among patients receiving trastuzumab. While there was recovery in LV systolic function after therapy cessation at 18 months, reduction in PFR/LVEDV appeared to persist. Thus, diastolic dysfunction may serve as a marker of trastuzumab-induced cardiotoxicity that needs to be confirmed in a larger study.

An Experimental Analysis of the Molecular Effects of Trastuzumab (Herceptin) and Fulvestrant (Falsodex), as Single Agents or in Combination, on Human HR+/HER2+ Breast Cancer Cell Lines and Mouse Tumor Xenografts

Purpose

To investigate the effects of trastuzumab (herceptin) and fulvestrant (falsodex) either in combination or alone, on downstream cell signaling pathways in lab-cultured human HR+/HER2+ breast cancer cell lines ZR-75-1 and BT-474, as well as on protein expression levels in mouse xenograft tissue.

Methods

Cells were cultivated in the presence of trastuzumab or fulvestrant or both. Molecular events that resulted in an inhibition of cell proliferation and cell cycle progression or in an increased rate of apoptosis were studied. The distribution and abundance of the proteins p-Akt and p-Erk expressed in these cells in response to single agents or combinatorial treatment were also investigated. In addition, the effects of trastuzumab and fulvestrant, either as single agents or in combination on tumor growth as well as on expression of the protein p-MED1 expressed in in vivo mouse xenograft models was also examined.

Results

Cell proliferation was increasingly inhibited by trastuzumab or fulvestrant or both, with a CI<1 and DRI>1 in both human cell lines. The rate of apoptosis increased only in the BT-474 cell line and not in the ZR-75-1 cell line upon treatment with fulvestrant and not trastuzumab as a single agent (P<0.05). Interestingly, fulvestrant, in combination with trastuzumab, did not significantly alter the rate of apoptosis (in comparison with fulvestrant alone), in the BT-474 cell line (P>0.05). Cell accumulation in the G1 phase of cell cycle was investigated in all treatment groups (P<0.05), and the combination of trastuzumab and fulvestrant reversed the effects of fulvestrant alone on p-Akt and p-Erk protein expression levels. Using ZR-75-1 or BT-474 to generate in vivo tumor xenografts in BALB/c athymic mouse models, we showed that a combination of both drugs resulted in a stronger inhibition of tumor growth (P<0.05) and a greater decrease in the levels of activated MED1 (p-MED1) expressed in tumor issues compared with the use of either drug as a single agent.

Conclusions

We demonstrate that the administration of trastuzumab and fulvestrant in combination results in positive synergistic effects on both, ZR-75-1 and BT-474 cell lines. This combinatorial approach is likely to reduce physiological side effects of both drugs, thus providing a theoretical basis for the use of such combination treatment in order to resolve HR+/HER2+ triple positive breast cancer that has previously been shown to be resistant to endocrine treatment alone.