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Background: As an oncologic emergency related to abnormalities in calcium metabolism, hypercalcemia associated with paraneoplastic syndrome and bone metastases is well known. Meanwhile, the incidence of hypocalcemia is low, except in cases associated with bone-modifying agents used for bone metastases. Hypocalcemia induced by bone-modifying agents typically occurs early after the initial administration, and its incidence can be significantly reduced by preventive administration of calcium and vitamin D3 supplements., Case Report: We report two cases of recurrent severe hypocalcemia occurring during chemotherapy for metastatic breast cancer with multiple bone metastases. Case 1: A 35-year-old Japanese woman developed metastases in the bone, liver, and ovaries during postoperative endocrine therapy for invasive lobular carcinoma of the breast. She underwent chemotherapy and treatment with denosumab. She experienced recurrent episodes of severe hypocalcemia subsequent to a change in the chemotherapy regimen. Case 2: A 65-year-old Japanese woman encountered multiple bone metastases after postoperative anti-human epidermal growth factor receptor 2 therapy and during endocrine therapy for invasive ductal carcinoma of the breast. She underwent anti-human epidermal growth factor receptor 2 therapy and treatment with denosumab. She experienced recurrent severe hypocalcemia subsequent to a change in the chemotherapy regimen to letrozole + lapatinib, trastuzumab emtansine, and lapatinib + capecitabine., Conclusions: We observed two cases of recurrent severe hypocalcemia in patients with advanced breast cancer and bone metastases after modifications to their therapy regimens. These cases differed from the typical hypocalcemia induced by bone-modifying agents. It is possible that antitumor drugs affect calcium and bone metabolism associated with bone metastases. While these cases are rare, it is crucial for oncologists to be aware of hypocalcemia not only at the initiation of bone-modifying agents but also throughout the entire antitumor therapy, as hypocalcemia can lead to fatal outcomes., (© 2024. The Author(s).)

Aims: Trastuzumab, the first humanized monoclonal antibody that targets human epidermal growth factor receptor 2 (ERBB2/HER2), is currently used as a first-line treatment for HER2 (+) tumours. However, trastuzumab increases the risk of cardiac complications without affecting myocardial structure, suggesting a distinct mechanism of cardiotoxicity., Methods and Results: We used medium from trastuzumab-treated human umbilical vein endothelial cells (HUVECs) to treat CCC-HEH-2 cells, the human embryonic cardiac tissue-derived cell lines, and human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to assess the crosstalk between vascular endothelial cells (VECs) and cardiomyocytes. Protein mass spectrometry analysis was used to identify the key factors from VECs that regulate the function of cardiomyocytes. We applied RNA-sequencing to clarify the mechanism, by which PTX3 causes cardiac dysfunction. We used an anti-human/rat HER2 (neu) monoclonal antibody to generate a rat model that was used to evaluate the effects of trastuzumab on cardiac structure and function and the rescue effects of lapatinib on trastuzumab-induced cardiac side effects. Medium from trastuzumab-treated HUVECs apparently impaired the contractility of CCC-HEH-2 cells and iPSC-CMs. PTX3 from VECs caused defective cardiomyocyte contractility and cardiac dysfunction in mice, phenocopying trastuzumab treatment. PTX3 affected calcium homoeostasis in cardiomyocytes, which led to defective contractile properties. EGFR/STAT3 signalling in VECs contributed to the increased expression and release of PTX3. Notably, lapatinib, a dual inhibitor of EGFR/HER2, could rescue the cardiac complications caused by trastuzumab by blocking the release of PTX3., Conclusion: We identified a distinct mode of cardiotoxicity, wherein the activation of EGFR/STAT3 signalling by trastuzumab in VECs promotes PTX3 excretion, which contributes to the impaired contractility of cardiomyocytes by inhibiting cellular calcium signalling. We confirmed that lapatinib could be a feasible preventive agent against trastuzumab-induced cardiac complications and provided the rationale for the combined application of lapatinib and trastuzumab in cancer therapy., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate approved for use in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Case reports have suggested an association between T-DM1 and portal hypertension. Purpose To evaluate the association of T-DM1 therapy with spleen volume changes and portal hypertension on CT scans and clinical findings compared with lapatinib and capecitabine therapy. Materials and Methods Patients with HER2-positive breast cancer who were administered at least two cycles of T-DM1 or lapatinib and capecitabine (controls) in a tertiary institution from 2001 to 2020 and who underwent CT before initial treatment and at least once during treatment were retrospectively enrolled. Spleen volume changes and the signs of portal hypertension (gastroesophageal varix [GEV], spontaneous portosystemic shunt [SPSS], and ascites) were evaluated at contrast-enhanced CT. Patients were followed until treatment ended or for 2 years after the start of treatment. Spleen volume changes were measured with a deep learning algorithm and evaluated by using a linear mixed model. The incidences of splenomegaly and portal hypertension were compared between the T-DM1 and control groups by using a χ 2 test or Fisher exact test. Results The T-DM1 group included 111 patients (mean age, 54 years ± 11 [SD]; 111 women) and the control group included 122 patients (mean age, 50 years ± 9; 121 women). Spleen volume progressively increased with T-DM1 therapy but was constant in the control group (104% ± 5 vs -1% ± 6 at the 33rd treatment cycle, respectively; P < .001). Incidences of splenomegaly (46% [51 of 111] vs 3% [four of 122] of patients; P < .001), GEV (11% [12 of 111] vs 1% [one of 122] of patients; P < .001), and SPSS (27% [30 of 111] vs 1% [one of 122] of patients; P < .001) were higher in the T-DM1 group than in the control group. Conclusion Trastuzumab emtansine therapy was associated with noncirrhotic portal hypertension at CT, with higher incidences of splenomegaly, gastroesophageal varix, and spontaneous portosystemic shunt than those with lapatinib and capecitabine therapy. © RSNA, 2022 Online supplemental material is available for this article.

Purpose: Human epidermal growth factor receptor 2 (HER2)-targeted therapies improve survival for patients with HER2-positive breast cancer but carry risks of hematologic, cardiopulmonary, gastro-hepatobiliary, and other adverse events (AEs). In this review, we describe published AE incidences for HER2-targeted therapies for metastatic breast cancer (mBC)., Methods: We searched PubMed and Embase to identify studies on HER2-targeted therapies in HER2-positive mBC, reporting on AEs of special interest, and published between January 1, 2009, and February 6, 2020. Treatment regimens were categorized into mutually exclusive therapy-based categories, with primary therapy determined by worldwide approval date., Results: One hundred and fifty-three included articles assessed a combined 29,238 patients treated with the following therapy-based regimens: trastuzumab or biosimilars (78 studies), lapatinib (40), T-DM1 (ado-trastuzumab emtansine) (20), pertuzumab (14), neratinib (8), MM-302 (1), T-DXd (2), tucatinib (3), and pyrotinib (3). While direct comparisons of AE incidence are not warranted owing to study heterogeneity, proportions of patients experiencing any Grade 3 + AE ranged across therapy-based regimens from 39.4% (lapatinib) to 66.3% (neratinib). The most common hematologic AE of special interest, of any grade and regardless of causality, was leukopenia/white blood cells decreased [21.4% (T-DXd)-46.2% (pyrotinib)]. Cardiopulmonary AEs of special interest included interstitial lung disease [2.7% (trastuzumab)-5.2% (T-DXd)], pneumonitis [0.2% (lapatinib)-7.4% (trastuzumab)], and decreased ejection fraction [1% (T-DXd)-13.6% (trastuzumab)]. Gastro-hepatobiliary AEs of special interest included nausea [33.9% (trastuzumab)-78.3% (T-DXd)], vomiting [19.2% (T-DM1)-48.2% (T-DXd)], diarrhea [19.6% (T-DM1)-96.9% (pyrotinib)], and hepatotoxicity [5.9% (lapatinib)-53.6% (T-DM1)]., Conclusion: Differing AE profiles for anti-HER2 therapies should be considered when assessing benefit-risk profile for treatment options., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The choice of the anti-HER2 agent depends on country-specific availability, the specific, previously administered anti-HER2 therapy and the relapse-free interval, although there is not much published data on the use of lapatinib after progression on pertuzumab and/or T-DM1. The aim of this research is to determine efficacy of lapatinib in this setting. This research included 111 patients with metastatic HER2 positive breast cancer who received lapatinib with capecitabine at The Oncology Institute of Vojvodina. Lapatinib was given to 83 patients after trastuzumab without prior exposure to pertuzumab or T-DM1 while 28 patients received lapatinib after prior exposure to trastuzumab, pertuzumab and/or T-DM1. In order to determine efficacy of lapatinib in both groups, we measured progression free survival (PFS) and overall survival (OS), as well as by subsets: hormonal status (ER-positive and/or PR-positive tumours versus ER-negative and PR-negative tumours), the number of positive axillary lymph nodes (four or more positive axillary lymph nodes versus less than four positive axillary lymph nodes), marker of proliferation (Ki-67 ≥ 30 versus Ki-67 < 30), disease free interval (metastatic recurrence ≤ 1 year after initial diagnosis versus metastatic recurrence > 1 year after initial diagnosis or de novo metastatic disease. Median PFS was 5.6 months (95% CI 4.6-6.6) in the group of patients who received lapatinib after prior exposure to trastuzumab, pertuzumab and/or T-DM 1 and 7.4 months (95% CI 6.1-10.2) in the group of patients who received lapatinib after trastuzumab (HR, 0.79; 95% CI 0.61-0.98; P = 0.09). The patients with negative prognostic factors such as hormone receptor negativity, more than four positive axillary lymph nodes, marker of proliferation Ki 67 ≥ 30 and metastatic recurrence ≤ 1 year after initial diagnosis, had a similar PFS, regardless of receiving lapatinib after prior exposure to trastuzumab, pertuzumab and/or T-DM1 or without prior exposure. Median OS was 10.1 months (95% CI 8.6-NR) in the group that received lapatinib after exposure to trastuzumab, pertuzumab and/or T-DM1 and 16.3 months (95% CI 14.4-20.2) in the group of patients who received lapatinib after trastuzumab (HR, 0.76; 95% CI, 0.59-0.94; P = 0.04). Patients with negative prognostic factors such as hormone receptor negativity, more than four positive axillary lymph nodes and marker of proliferation Ki 67 ≥ 30, had no distinctly worse OS, regardless of receiving lapatinib after prior exposure to trastuzumab, pertuzumab and/or T-DM1 or without prior exposure. Lapatinib with capecitabine is an effective therapeutic option, especially in patients with negative prognostic factors, who have received prior chemotherapy, trastuzumab, pertuzumab, T-DM1 and remains an acceptable option for HER2 positive metastatic breast cancer until the novel drugs are approved in developing countries.

Lapatinib, an orally administered small-molecule tyrosine kinase inhibitor (SM-TKI), is an effective treatment for ErbB2-positive breast cancer. However, its efficacy as one of the targeted cancer therapies has been hampered by several adverse effects, especially gastrointestinal toxicity, commonly manifested as diarrhoea. Although it can be generally tolerated, diarrhoea is reported as the most common and most impactful on a patient's quality of life and associated with treatment interruption. Severe diarrhoea can result in malabsorption, leading to dehydration, fatigue, and even death. ErbB1 is an epidermal growth factor profoundly expressed in normal gut epithelium while lapatinib is a dual ErbB1/ErbB2 tyrosine kinase inhibitor. Thus, ErbB1 inhibition by lapatinib may affect gut homeostasis leading to diarrhoea. Nevertheless, the underlying mechanisms remain unclear. This review article provides evidence of the possible mechanisms of lapatinib-induced diarrhoea that may be related to/or modulated by ErbB1. Insight regarding the involvement of ErbB1 in the pathophysiological changes such as inflammation and intestinal permeability as the underlying cause of diarrhoea is covered in this article., Competing Interests: The authors declare that they have no competing interests., (Copyright © 2022 Raja Nur Firzanah Syaza Raja Sharin et al.)

Adverse drug reactions (ADRs) of targeted therapy drugs (TTDs) are frequently unexpected and long-term toxicities detract from exceptional efficacy of new TTDs. In this proof-of-concept study, we explored how molecular causation involved in trastuzumab-induced cardiotoxicity changes when trastuzumab was given in combination with doxorubicin, tamoxifen, paroxetine, or lapatinib. The data analytical platform Molecular Health Effect was utilized to map population ADR data from the US Food and Drug Administration (FDA) Adverse Event Reporting System to chemical and biological databases (such as UniProt and Reactome), for hypothesis generation regarding the underlying molecular mechanisms causing cardiotoxicity. Disproportionality analysis was used to assess the statistical relevance between adverse events of interest and molecular causation. Literature search was performed to compare the established hypotheses to published experimental findings. We found that the combination therapy of trastuzumab and doxorubicin may affect mitochondrial dysfunction in cardiomyocytes through different molecular pathways such as BCL-X and PGC-1α proteins, leading to a synergistic effect of cardiotoxicity. We found, on the other hand, that trastuzumab-induced cardiotoxicity would be diminished by concomitant use of tamoxifen, paroxetine, and/or lapatinib. Tamoxifen and paroxetine may cause less cardiotoxicity through an increase in antioxidant activities, such as glutathione conjugation. Lapatinib may decrease the apoptotic effects in cardiomyocytes by altering the effects of trastuzumab on BCL-X proteins. This patient-centered systems-based approach provides, based on the trastuzumab-induced ADR cardiotoxicity, an example of how to apply reverse translation to investigate ADRs at the molecular pathway and target level to understand the causality and prevalence during drug development of novel therapeutics., (© 2022 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Epidermal growth factor receptors 1 and 2 (EGFR and HER2) are frequently overexpressed in various malignancies. Lapatinib is a dual tyrosine kinase inhibitor that inhibits both EGFR and HER2. Although a phase III trial failed to show the survival benefits of lapatinib treatment after first-line chemotherapy in patients with EGFR/HER2-positive metastatic urothelial carcinoma, the efficacy of lapatinib for untreated urothelial carcinoma is not well defined. Here, we describe the therapeutic efficacy of lapatinib as a first-line treatment in a canine model of muscle-invasive urothelial carcinoma. In this non-randomized clinical trial, we compared 44 dogs with naturally occurring urothelial carcinoma who received lapatinib and piroxicam, with 42 age-, sex-, and tumor stage-matched dogs that received piroxicam alone. Compared to the dogs treated with piroxicam alone, those administered the lapatinib/piroxicam treatment had a greater reduction in the size of the primary tumor and improved survival. Exploratory analyses showed that HER2 overexpression was associated with response and survival in dogs treated with lapatinib. Our study suggests that lapatinib showed encouraging durable response rates, survival, and tolerability, supporting its therapeutic use for untreated advanced urothelial carcinoma in dogs. The use of lapatinib as a first-line treatment may be investigated further in human patients with urothelial carcinoma., (© 2022. The Author(s).)

Lapatinib (LAP) is an important anti-cancer drug and is frequently alongside doxorubicin (DOX) as a combination therapy for better anti-cancer efficacy. However, many studies have reported that LAP in combination with DOX may induce highly cardiotoxicity. Accordingly, we aimed to explore the potential mechanism involved in the synergistic effect of LAP in DOX-induced cardiotoxicity. Here, cell counting kit-8 was used to detect cell viability and lactate dehydrogenase measurement was performed to assess cell injury. Cell apoptosis was evaluated by TUNEL assay and western blot assay. Mitochondrial dysfunction was identified by JC-1 assay, adenosine triphosphate (ATP) and Cytochrome C. Moreover, the activity of ROS, SOD, CAT and GSH were measured to elucidate oxidative stress level. Ferroptosis was examined by levels of Fe 2+ , GPX4 and ASCL4. Expressions of PI3K/AKT signaling were identified by western blot assay. The results revealed that LAP inhibited the cell viability and exacerbated cell injury induced by Dox, as well as increased cell apoptosis. LAP aggravated DOX-induced mitochondria damage by changed mitochondrial membrane potential, decreased ATP and increased level of Cytochrome C. In addition, the combination of LAP and DOX induced oxidative stress and ferroptosis in H9c2 cells. The activation of PI3K/AKT signaling reversed the detrimental effects of LAP on DOX-induced H9c2 cells. The data in this study showed for the first time that LAP aggravated Dox-induced cardiotoxicity by promoting oxidative stress and ferroptosis in cardiomyocytes via PI3K/AKT-mediated mitochondrial dysfunction, suggesting that PI3K/AKT activation is a promising cardioprotective strategy for DOX /LAX combination therapies.