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Background: Gene mutations play a crucial role in the occurrence and development of tumors, particularly in breast cancer (BC). Neoadjuvant therapy (NAT) has shown greater clinical benefit in HER2‐positive breast cancer. However, further clinical investigation is needed to fully understand the correlation between genetic mutations and NAT efficacy and the long‐term prognosis in HER2‐positive BC. Methods: This was a retrospective cohort study of 222 patients receiving NAT between 2017 and 2021 in the Department of Breast Surgery of Fudan University Shanghai Cancer Center. Tumor samples from these patients were subjected to Next Generation Sequencing (NGS) to analyze mutations in 513 cancer‐related genes. This study aimed to investigate the association between these genetic mutations and postoperative pathological complete response (pCR), as well as their impact on disease‐free survival (DFS). Results: In total, 48.65% patients reached pCR, ER‐negative status (p < 0.001), PR‐negative status (p < 0.001), Ki67 ≥ 20 (p = 0.011), and dual‐targeted therapy (p < 0.001) were all associated with enhanced pCR rates. The frequency of somatic alterations in TP53 (60%), PIK3CA (15%), and ERBB2 (11%) was highest. In the HER2+/HR‐ cohort, patients who achieved pCR had a significant benefit in prognosis (HR = 3.049, p = 0.0498). KMT2C (p = 0.036) and TP53 (p = 0.037) mutations were significantly increased in patients with DFS events. Moreover, TP53 mutations had prognostic significance in HER2‐positive BC patients with HR‐negative (HR = 3.712, p = 0.027) and pCR (HR = 6.253, p = 0.027) status and who received herceptin‐only targeted therapy (HR = 4.145, p = 0.011). Conclusions: The genetic mutation profiles of Chinese HER2+ patients who received NAT were discrepant with respect to HR status or DFS events. TP53 mutations have significant prognostic value in patients with NAT for HER2‐positive BC and patients benefit differently depending on HR status, the neoadjuvant regimen and response, which highlights the significance of genetic factors in treatment customization based on individual genetic and clinical characteristics. [ABSTRACT FROM AUTHOR]

Abstract Near‐infrared photoimmunotherapy (NIR‐PIT) is a novel form of cancer treatment using conjugates of antibody against overexpressed antigens in cancers and photoabsorber IRDye700DX. HER2 is overexpressed in various cancers, for which molecular targeted therapy such as trastuzumab has been developed. The present study investigated the efficacy potential of HER2‐targeted NIR‐PIT using trastuzumab‐IRDye700DX conjugate (Tra‐IR700) in HER2‐positive breast cancer. We first examined the reactivity of Tra‐IR700 and the cytotoxicity of NIR‐PIT in vitro. HER2‐positive BT‐474 and SK‐BR‐3 cells and HER2‐negative BT‐20 cells were used. Tra‐IR700 fluorescence was only observed in HER2‐positive breast cancer cell lines, and the fluorescence was localized to the cell surface. Furthermore, HER2‐positive breast cancer cell lines treated with NIR‐PIT showed swelling and blebbing shortly after irradiation, and eventually increased PI‐positive dead cells. Next, tumor accumulation of Tra‐IR700 and tumor damage by NIR‐PIT were examined in vivo. Tra‐IR700 was administered intravenously to a xenograft model in which BT‐474 cells were implanted subcutaneously in BALB/c nude mice. Tra‐IR700 fluorescence was the highest in tumor tissue 1 day after administration, and the fluorescence was localized to the cell membrane of tumor cells. At this time point, NIR‐PIT resulted in diffuse necrosis of tumor tissues 1 day after irradiation. These results suggest that NIR‐PIT with Tra‐IR700 induces a highly selective therapeutic effect in a HER2‐positive breast cancer model. NIR‐PIT using Tra‐IR700 is expected to be a novel treatment for HER2‐positive cancers, including breast cancer.

Near‐infrared photoimmunotherapy (NIR‐PIT) is a novel form of cancer treatment using conjugates of antibody against overexpressed antigens in cancers and photoabsorber IRDye700DX. HER2 is overexpressed in various cancers, for which molecular targeted therapy such as trastuzumab has been developed. The present study investigated the efficacy potential of HER2‐targeted NIR‐PIT using trastuzumab‐IRDye700DX conjugate (Tra‐IR700) in HER2‐positive breast cancer. We first examined the reactivity of Tra‐IR700 and the cytotoxicity of NIR‐PIT in vitro. HER2‐positive BT‐474 and SK‐BR‐3 cells and HER2‐negative BT‐20 cells were used. Tra‐IR700 fluorescence was only observed in HER2‐positive breast cancer cell lines, and the fluorescence was localized to the cell surface. Furthermore, HER2‐positive breast cancer cell lines treated with NIR‐PIT showed swelling and blebbing shortly after irradiation, and eventually increased PI‐positive dead cells. Next, tumor accumulation of Tra‐IR700 and tumor damage by NIR‐PIT were examined in vivo. Tra‐IR700 was administered intravenously to a xenograft model in which BT‐474 cells were implanted subcutaneously in BALB/c nude mice. Tra‐IR700 fluorescence was the highest in tumor tissue 1 day after administration, and the fluorescence was localized to the cell membrane of tumor cells. At this time point, NIR‐PIT resulted in diffuse necrosis of tumor tissues 1 day after irradiation. These results suggest that NIR‐PIT with Tra‐IR700 induces a highly selective therapeutic effect in a HER2‐positive breast cancer model. NIR‐PIT using Tra‐IR700 is expected to be a novel treatment for HER2‐positive cancers, including breast cancer. [ABSTRACT FROM AUTHOR]

HER2‐targeted therapy, especially the anti‐HER2 antibody trastuzumab, is standard for HER2‐positive breast cancer; however, its efficacy is limited in a subpopulation of patients. HER3 ligand (heregulin)‐dependent HER2‐HER3 interactions play a critical role in the evasion of apoptosis and are therefore a target for oncotherapy to treat HER2‐positive breast cancer. The anti‐HER2 antibody pertuzumab and anti‐HER3 antibody patritumab both target this heregulin–HER3‐HER2 complex in different ways. This study examined the anticancer efficacy of dual HER2 and HER3 blockade in trastuzumab‐resistant HER2‐positive breast cancer. HER2‐positive SKBR3 or BT474 cells overexpressing heregulin (SKBR3‐HRG, BT474‐HRG) were used to evaluate the efficacy of trastuzumab, pertuzumab, and patritumab in vitro by performing cell viability, immunoblotting, and clonogenic assays. The effects of these agents were then evaluated in vivo using BT474‐HRG and an intrinsic heregulin‐expressing and HER2‐positive JIMT‐1 xenograft models. SKBR3‐HRG and BT474‐HRG cells lost sensitivity to trastuzumab, which was accompanied by Akt activation. Unexpectedly, trastuzumab in combination with pertuzumab or patritumab also showed limited efficacy toward these cells. In contrast, trastuzumab/pertuzumab/patritumab triple treatment demonstrated potent anticancer efficacy, concomitant with strong repression of Akt. Finally, in heregulin‐expressing BT474‐HRG and JIMT‐1 xenograft models, the addition of pertuzumab and patritumab to trastuzumab also enhanced antitumor efficacy leading to tumor regression. The current study found that triple blockade of HER2 and HER3 using trastuzumab, pertuzumab, and patritumab could overcome resistance to trastuzumab therapy in heregulin‐expressing and HER2‐positive breast cancer, which could be exploited clinically. HER2‐targeted therapy, especially the anti‐HER2 antibody trastuzumab, is standard for HER2‐positive breast cancer; however, its efficacy is limited in a subpopulation of patients. The current study found that blockade of HER2 and HER3 using pertuzumab and patritumab could overcome resistance to trastuzumab therapy in heregulin‐expressing and HER2‐positive breast cancer, which could be exploited clinically. [ABSTRACT FROM AUTHOR]