UNASSIGNED: Cardiotoxicity (CTX) induced by adjuvant chemotherapy is a significant factor that impacts the prognosis and quality of life in breast cancer (BC) patients. In this study, we aimed to investigate the changes in epicardial adipose tissue (EAT) before and after treatment in BC patients who received anthracyclines adjuvant chemotherapy protocol (AC-T) and anthracyclines combined with trastuzumabadjuvant chemotherapy protocol (AC-TH). Additionally, we assessed whether there were any differences in the changes in EAT between the two groups of patients. Our objective was to examine the effects of anthracyclines and trastuzumab on EAT and determine the potential role of EAT changes on CTX.
UNASSIGNED: We reviewed female BC patients who were treated with adjuvant chemotherapy protocols of AC-T and AC-TH, all of whom underwent baseline (T0) and follow-up (T1) chest computed tomography (CT) and echocardiography. A cohort of healthy women, matched in age, underwent two chest CTs. EAT was quantified on chest CT using semi-automated software. CTX was defined as a > 10% reduction in left ventricular ejection fraction (LVEF) from baseline, with an absolute value of < 53%.
UNASSIGNED: A total of 41 BC patients were included in the study, with 23 patients in the AC-T group and 18 patients in the AC-TH group. Additionally, 22 healthy females were included as the normal group. None of the BC patients developed CTX after chemotherapy. The age did not differ significantly between the normal group and the AC-T group (p = 0.341) or the AC-TH group (p = 0.853). Similarly, the body mass index (BMI) of the normal group was comparable to that of the AC-T group (p = 0.377, 0.346) and the AC-TH group (p = 0.148, 0.119) before and after chemotherapy. The EAT volume index (mL/kg/ m 2 ) was significantly higher in both the AC-T group (5.11 ± 1.85 vs. 4.34 ± 1.55, p < 0.001) and the AC-TH group (4.53 ± 1.61 vs. 3.48 ± 1.62, p < 0.001) at T1 compared with T0. In addition, both the AC-T group (-72.95 ± 5.01 vs. -71.22 ± 3.91, p = 0.005) and the AC-TH group (-72.55 ± 5.27 vs. -68.20 ± 5.98, p < 0.001) exhibited a significant decrease in EAT radiodensity (HU) at T1 compared to T0. However, there was no significant difference observed in the normal group. At T0, no difference was seen in EAT volume index (4.34 ± 1.55 vs. 3.48 ± 1.62, p = 0.090) and radiodensity (-71.22 ± 3.91 vs. -68.20 ± 5.98, p = 0.059) between the AC-T and AC-TH groups. Similarly, at T1, there was still no significant difference observed in the EAT volume index (-5.11 ± 1.85 vs. 4.53 ± 1.61, p = 0.308) and radiodensity (-72.95 ± 5.00 vs. -72.54 ± 5.27, p = 0.802) between the two groups.
UNASSIGNED: BC patients who underwent AC-T and AC-TH adjuvant chemotherapy protocols demonstrated a significant rise in the volume index of EAT, along with a substantial reduction in its radiodensity post-chemotherapy. These findings indicate that alterations in EAT could potentially aid in identifying cardiac complications caused by chemotherapeutic agents and remind clinicians to focus on changes in EAT after adjuvant chemotherapy in BC patients to prevent the practical occurrence of CTX.

About 20% of breast cancer patients are positive for HER2. The efficacy of current treatments is limited by primary and secondary resistance to trastuzumab. tRNA-derived fragments (tRFs) have shown crucial regulatory roles in various cancers. This study aimed to evaluate the role of tRF-27 in regulating the resistance of HER2-positive breast cancer against trastuzumab. tRF-27 was highly expressed in trastuzumab-resistant cells, and its expression level could predict the resistance to trastuzumab. High expression of tRF-27 promoted the growth and proliferation of trastuzumab-exposed cells. RNA-pulldown assay and mass spectrometry were performed to identify Ras GTPase-activating protein-binding proteins 1 and 2 (G3BPs) (two proteins targeted by tRF-27); RNA-immunoprecipitation (RIP) to confirm their bindings; co-immunoprecipitation (co-IP) and RNA-pulldown assay to determine the binding domains between G3BPs and tRF-27.tRF-27 bound to the nuclear transport factor 2 like domain(NTF2 domain) of G3BPs through a specific sequence. tRF-27 relied on G3BPs and NTF2 domain to increase trastuzumab tolerance. tRF-27 competed with lysosomal associated membrane protein 1(LAMP1) for NTF2 domain, thereby inhibiting lysosomal localization of G3BPs and tuberous sclerosis complex (TSC). Overexpression of tRF-27 inhibited phosphorylation of TSCs and promoted the activation of mechanistic target of rapamycin complex 1(MTORC1) to enhance cell proliferation and entice the resistance of HER2-positive breast cancer against trastuzumab.

Breast cancer (BC) is the prevailing malignancy among women, with HER2 overexpression observed in 20-30 % of all BC, thereby serving as a prognostic indicator for unfavorable outcomes in affected individuals. There is a necessity to establish innovative treatment protocols to expand the therapeutic alternatives accessible for managing HER2-positive BC. In this study, we report a case of HER2-positive BC that was managed in our department using a combination of three targeted drugs (Trastuzumab, Pertuzumab and Pyrotinib) along with chemotherapy. The treatment resulted in a pathological complete response (pCR) and was observed to be well-tolerated, without any significant adverse reactions. Hence, the combination of Pyrotinib and Dual HER2 blockade treatment shows promise as a neoadjuvant therapy for locally advanced HER2-positive BC to achieve a pCR in surgery. Nevertheless, this conclusion necessitates additional validation via meticulously designed clinical research investigations encompassing larger patient populations.

OBJECTIVE: Resistance to targeted therapy is one of the critical obstacles in cancer management. Resistance to trastuzumab frequently develops in the treatment for HER2+ cancers. The role of protein tyrosine phosphatases (PTPs) in trastuzumab resistance is not well understood. In this study, we aim to identify pivotal PTPs affecting trastuzumab resistance and devise a novel counteracting strategy.
METHODS: Four public datasets were used to screen PTP candidates in relation to trastuzumab responsiveness in HER2+ breast cancer. Tyrosine kinase (TK) arrays were used to identify kinases that linked to protein tyrosine phosphate receptor type O (PTPRO)-enhanced trastuzumab sensitivity. The efficacy of small activating RNA (saRNA) in trastuzumab-conjugated silica nanoparticles was tested for PTPRO upregulation and resistance mitigation in cell models, a transgenic mouse model, and human cancer cell line-derived xenograft models.
RESULTS: PTPRO was identified as the key PTP which influences trastuzumab responsiveness and patient survival. PTPRO de-phosphorated several TKs, including the previously overlooked substrate ERBB3, thereby inhibiting multiple oncogenic pathways associated with drug resistance. Notably, PTPRO, previously deemed \"undruggable,\" was effectively upregulated by saRNA-loaded nanoparticles. The upregulated PTPRO simultaneously inhibited ERBB3, ERBB2, and downstream SRC signaling pathways, thereby counteracting trastuzumab resistance.
CONCLUSIONS: Antibody-conjugated saRNA represents an innovative approach for targeting \"undruggable\" PTPs.

Antibody-drug conjugates (ADCs) have demonstrated effectiveness in treating various cancers, particularly exhibiting specificity in targeting human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Recent advancements in phase 3 clinical trials have broadened current understanding of ADCs, especially trastuzumab deruxtecan, in treating other HER2-expressing malignancies. This expansion of knowledge has led to the US Food and Drug Administration\'s approval of trastuzumab deruxtecan for HER2-positive and HER2-low breast cancer, HER2-positive gastric cancer, and HER2-mutant nonsmall cell lung cancer. Concurrent with the increasing use of ADCs in oncology, there is growing concern among health care professionals regarding the rise in the incidence of interstitial lung disease or pneumonitis (ILD/p), which is associated with anti-HER2 ADC therapy. Studies on anti-HER2 ADCs have reported varying ILD/p mortality rates. Consequently, it is crucial to establish guidelines for the diagnosis and management of ILD/p in patients receiving anti-HER2 ADC therapy. To this end, a panel of Chinese experts was convened to formulate a strategic approach for the identification and management of ILD/p in patients treated with anti-HER2 ADC therapy. This report presents the expert panel\'s opinions and recommendations, which are intended to guide the management of ILD/p induced by anti-HER2 ADC therapy in clinical practice.

BACKGROUND: Inetetamab is the first domestically developed innovative anti-HER2 monoclonal antibody in China, proven effective and safe in HER2-positive advanced breast cancer. However, its efficacy and safety in neoadjuvant treatment of HER2-positive locally advanced breast cancer (LABC) remain to be validated.
METHODS: This prospective cohort study aimed to evaluate the efficacy and safety of inetetamab combined with pertuzumab, taxanes, and carboplatin (TCbIP) in neoadjuvant therapy for HER2-positive LABC, comparing it to data from patients treated with the TCbHP regimen (trastuzumab combined with pertuzumab, taxanes, and carboplatin) using propensity score matching (PSM). The primary endpoint was total pathological complete response (tpCR). Adverse events (AEs), objective response rate (ORR), and near-pCR were key secondary endpoints.
RESULTS: Forty-four patients with clinical stage IIA-IIIC HER2-positive LABC were prospectively enrolled and treated with the TCbIP regimen. The tpCR rate among 28 patients who completed surgery was 60.7%, comparable to and slightly higher than the TCbHP group in PSM (60.7% vs. 53.6%, P = 0.510). The ORR was 96.4%, and the DCR reached 100.0%. The most common ≥ grade 3 AE was neutropenia (21.4% vs. 11.9%, P = 0.350). No significant reduction in left ventricular ejection fraction was observed, and no patient withdrew from treatment due to AEs.
CONCLUSIONS: Neoadjuvant therapy with TCbIP showed good efficacy and safety in patients with HER2-positive LABC and might be another promising option for neoadjuvant treatment.
BACKGROUND: NCT05749016 (registration date: Nov 01, 2021).

Resistance to HER2-targeted therapy is the major cause of treatment failure in patients with HER2+ breast cancer (BC). Given the key role of immune microenvironment in tumor development, there is a lack of an ideal prognostic model that fully accounts for immune infiltration. In this study, WGCNA analysis was performed to discover the relationship between immune-related signaling and prognosis of HER2+ BC. After Herceptin-resistant BC cell lines established, transcriptional profiles of resistant cell line and RNA-sequencing data from GSE76360 cohort were analyzed for candidate genes. 85 samples of HER2+ BC from TCGA database were analyzed by the Cox regression, XGBoost and Lasso algorithm to generalize a credible immune-related prognostic index (IRPI). Correlations between the IRPI signature and tumor microenvironment were further analyzed by multiple algorithms, including single-cell RNA sequencing data analysis. Patients with high IRPI had suppressive tumor immune microenvironment and worse prognosis. The suppression of type I interferon signaling indicated by the IRPI in Herceptin-resistant HER2+ BC was validated. And we elucidated that the suppression of cGAS-STING pathway is the key determinant underlying immune escape in Herceptin-resistant BC with high IRPI. A combination of STING agonist and DS-8201 could serve as a new strategy for Herceptin-resistant HER2+ BC.

Gastric cancer is one of the most prevalent cancers worldwide, and human epidermal growth factor receptor 2 (HER2)-positive cases account for approximately 20% of the total cases. Currently, trastuzumab + chemotherapy is the recommended first-line treatment for patients with HER2-positive advanced gastric cancer, and the combination has exhibited definite efficacy in HER2-targeted therapy. However, the emergence of drug resistance during treatment considerably reduces its effectiveness; thus, it is imperative to investigate the potential mechanisms underlying resistance. In the present review article, we comprehensively introduce multiple mechanisms underlying resistance to trastuzumab in HER2-positive gastric cancer cases, aiming to provide insights for rectifying issues associated with resistance to trastuzumab and devising subsequent treatment strategies.

BACKGROUND: Trastuzumab and pertuzumab combination has been approved for the treatment of patients with HER2-positive metastatic breast cancer. However, trastuzumab and pertuzumab combination did not show improvement in overall survival in patients with HER2-positive metastatic gastric cancer.
METHODS: We developed a new HER2-targeted monoclonal antibody, HLX22, targeting HER2 subdomain IV as trastuzumab but with non-overlapping epitopes. We examined the antitumor effects of this novel HER2-antibody in gastric cell lines and cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) models.
RESULTS: HLX22 in combination with HLX02 (trastuzumab biosimilar) induced enhancement of HER2/HER2 homodimers and HER2/EGFR heterodimers internalization, which ultimately led to the reduction in signal transductions involving STAT3, P70 S6, and AKT; gene expressions of FGF-FGFR-PI3K-MTOR, EGF-EGFR-RAS, TGF-β-SMAD, PLCG and cell cycle progression related pathways that favor tumor development, proliferation, progression, migration and survival in gastric cancer cell line NCI-N87 were also reduced. These differing but complementary actions contributed to the synergistic antitumor efficacy of the HLX22 and HLX02 combination in gastric cancer cell lines, CDX and PDX. In addition, HLX22 in combination with HLX02 demonstrated stronger antitumor efficacy than HLX02 and HLX11 (a potential pertuzumab biosimilar) combination treatment both in vitro and in vivo.
CONCLUSIONS: These results suggested that the application of non-competing antibodies HLX22 and HLX02 targeting HER2 subdomain IV together may be of substantial benefit to gastric cancer patients who currently respond suboptimal to trastuzumab therapy.

Chimeric antigen receptor (CAR) T cell therapy shows promise in treating malignant tumors. However, the use of human epidermal growth factor receptor-2 (HER2) CAR-T cells carries the risk of severe toxicity, including cytokine release syndrome, due to their \"on-target off-tumor\" recognition of HER2. Enhancing the quality and functionality of HER2 CARs could greatly improve the therapeutic potential of CAR-T cells. In this study, we developed a novel anti-HER2 monoclonal antibody, Ab8, which targets domain III of HER2, distinct from the domain IV recognition of trastuzumab. Although two anti-HER2 mAbs induced similar levels of antibody-dependent cellular cytotoxicity, trastuzumab-based CAR-T cells exhibited potent antitumor activity against HER2-positive cancer cells. In conclusion, our findings provide scientific evidence that antibody recognition of the membrane-proximal domain promotes the anti-tumor response of HER2-specific CAR-T cells.