Monitoring changing patterns in HER2 addiction by liquid biopsy in advanced breast cancer patients.

BACKGROUND: During targeted treatment, HER2-positive breast cancers invariably lose HER2 DNA amplification. In contrast, and interestingly, HER2 proteins may be either lost or gained. To longitudinally and systematically appreciate complex/discordant changes in HER2 DNA/protein stoichiometry, HER2 DNA copy numbers and soluble blood proteins (aHER2/sHER2) were tested in parallel, non-invasively (by liquid biopsy), and in two-dimensions, hence HER2-2D. METHODS: aHER2 and sHER2 were assessed by digital PCR and ELISA before and after standard-of-care treatment of advanced HER2-positive breast cancer patients (n=37) with the antibody-drug conjugate (ADC) Trastuzumab-emtansine (T-DM1). RESULTS: As expected, aHER2 was invariably suppressed by T-DM1, but this loss was surprisingly mirrored by sHER2 gain, sometimes of considerable entity, in most (30/37; 81%) patients. This unorthodox split in HER2 oncogenic dosage was supported by reciprocal aHER2/sHER2 kinetics in two representative cases, and an immunohistochemistry-high status despite copy-number-neutrality in 4/5 available post-T-DM1 tumor re-biopsies from sHER2-gain patients. Moreover, sHER2 was preferentially released by dying breast cancer cell lines treated in vitro by T-DM1. Finally, sHER2 gain was associated with a longer PFS than sHER2 loss (mean PFS 282 vs 133 days, 95% CI [210-354] vs [56-209], log-rank test p=0.047), particularly when cases (n=11) developing circulating HER2-bypass alterations during T-DM1 treatment were excluded (mean PFS 349 vs 139 days, 95% CI [255-444] vs [45-232], log-rank test p=0.009). CONCLUSIONS: HER2 gain is adaptively selected in tumor tissues and recapitulated in blood by sHER2 gain. Possibly, an increased oncogenic dosage is beneficial to the tumor during anti-HER2 treatment with naked antibodies, but favorable to the host during treatment with a strongly cytotoxic ADC such as T-DM1. In the latter case, HER2-gain tumors may be kept transiently in check until alternative oncogenic drivers, revealed by liquid biopsy, bypass HER2. Whichever the interpretation, HER2-2D might help to tailor/prioritize anti-HER2 treatments, particularly ADCs active on aHER2-low/sHER2-low tumors. TRIAL REGISTRATION: NCT05735392 retrospectively registered on January 31, 2023 https://www. CLINICALTRIALS: gov/search?term=NCT05735392.

Trastuzumab-functionalized bionic pyrotinib liposomes for targeted therapy of HER2-positive breast cancer.

In this study, we prepared a bionic nanosystem of trastuzumab-functionalized SK-BR-3 cell membrane hybrid liposome-coated pyrotinib (Ptb-M-Lip-Her) for the treatment of HER2-positive breast cancer. Transmission electron microscopy, dynamic light scattering, polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting were used to verify the successful preparation of Ptb-M-Lip-Her. In vitro drug release experiments proved that Ptb-M-Lip-Her had a sustained release effect. Cell uptake experiments and in vivo imaging experiments proved that Ptb-M-Lip-Her had good targeting ability to homologous tumor cells (SK-BR-3). The results of cell experiments such as MTT, flow cytometry, immunofluorescence staining and in vivo antitumor experiments showed that Ptb-M-Lip-Her could significantly promote apoptosis and inhibit the proliferation of SK-BR-3 cells. These results clearly indicated that Ptb-M-Lip-Her may be a promising biomimetic nanosystem for targeted therapy of HER2-positive breast cancer.

Elimination of radiation-induced senescent cancer cells and stromal cells in vitro by near-infrared photoimmunotherapy.

INTRODUCTION: Therapy-induced senescent cancer and stromal cells secrete cytokines and growth factors to promote tumor progression. Therefore, senescent cells may be novel targets for tumor treatment. Near-infrared photoimmunotherapy (NIR-PIT) is a highly tumor-selective therapy that employs conjugates of a molecular-targeting antibody and photoabsorber. Thus, NIR-PIT has the potential to be applied as a novel senolytic therapy. This study aims to investigate the efficacy of NIR-PIT treatment on senescent cancer and stromal cells. METHODS: Two cancer cell lines (human lung adenocarcinoma A549 cells and human pancreatic cancer MIA PaCa-2 cells) and two normal cell lines (mouse fibroblast transfected with human epidermal growth factor receptor 2 [HER2] cells and human fibroblast WI38 cells) were used. The cytotoxicity of NIR-PIT was evaluated using anti-epidermal growth factor receptor (EGFR) antibody panitumumab and anti-HER2 antibody transtuzumab. RESULTS: Cellular senescence was induced in A549 and MIA PaCa-2 cells by 10 Gy γ-irradiation. The up-regulation of cellular senescence markers and characteristic morphological changes in senescent cells, including enlargement, flattening, and multinucleation, were observed in cancer cells after 5 days of γ-irradiation. Then, NIR-PIT targeting EGFR was performed on these senescent cancer cells. The NIR-PIT induced morphological changes, including bleb formation, swelling, and the inflow of extracellular fluid, and induced a significant decrease in cellular viability. These results suggested that NIR-PIT may induce cytotoxicity using the same mechanism in senescent cancer cells. In addition, similar morphological changes were also induced in radiation-induced senescent 3T3-HER2 fibroblasts by NIR-PIT targeting human epidermal growth factor receptor 2. CONCLUSION: NIR-PIT eliminates both senescent cancer and stromal cells in vitro suggesting it may be a novel strategy for tumor treatment.

Synthesis and evaluation of antibody-drug conjugates with high drug-to-antibody ratio using dimaleimide-DM1 as a linker- payload.

The notable characteristics of recently emerged Antibody-Drug Conjugates (ADCs) encompass the targeting of Human Epidermal growth factor Receptor 2 (HER2) through monoclonal antibodies (mAbs) and a high ratio of drug to antibody (DAR). The achievements of Kadcyla® (T-DM1) and Enhertu® (T-Dxd) have demonstrated that HER2-targeting antibodies, such as trastuzumab, have shown to be competitive in terms of efficacy and price for development. Furthermore, with the arrival of T-Dxd and Trodelvy®, high-DAR (7-8) ADCs, which differ from the moderate DAR (3-4) ADCs that were formerly regarded as conventional, are being acknowledged for their worth. Following this trend of drug development, we endeavored to develop a high-DAR ADC using a straightforward approach involving the utilization of DM1, a highly potent substance, in combination with the widely recognized trastuzumab. To achieve a high DAR, DM1 was conjugated to reduced cysteine through the simple design and synthesis of various dimaleimide linkers with differing lengths. Using LC and MS analysis, we have demonstrated that our synthesis methodology is uncomplicated and efficacious, yielding trastuzumab-based ADCs that exhibit a remarkable degree of uniformity. These ADCs have been experimentally substantiated to exert an inhibitory effect on cancer cells in vitro, thus affirming their value as noteworthy additions to the realm of ADCs.

Phase Ib dose-escalation trial of taselisib (GDC-0032) in combination with HER2-directed therapies in patients with advanced HER2+ breast cancer.

BACKGROUND: In most patients with advanced human epidermal growth factor receptor-2-positive (HER2+) breast cancer, anti-HER2 therapies fail due to the development of acquired resistance, potentially mediated through phosphoinositide-3-kinase (PI3K) signaling. We investigated adding taselisib, an α-selective potent oral inhibitor of PI3K, to different HER2-directed regimens in order to improve disease control. PATIENTS AND METHODS: Patients (n = 68) with advanced HER2+ breast cancer were enrolled to this open-label, dose-escalation phase Ib study. The primary endpoint was defining the maximal tolerated dose (MTD) for the various taselisib-containing combinations. The secondary endpoint was safety. Exploratory endpoints included circulating tumor DNA analysis. The study included four cohorts: (A) taselisib + trastuzumab emtansine (T-DM1), (C) taselisib + trastuzumab and pertuzumab (TP), (D) taselisib + TP + paclitaxel, and (E) taselisib + TP + fulvestrant. RESULTS: Following dose escalation, the taselisib MTD was defined as 4 mg once daily. Treatment was associated with significant toxicities, as 34 out of 68 patients experienced grade ≥3 adverse events (AEs) attributed to taselisib, the most common all-grade AEs being diarrhea, fatigue, and oral mucositis. At a median follow-up of 43.8 months, median progression-free survival (PFS) for the MTD-treated population in cohorts A, C, and E was 6.3 [95% confidence interval (CI) 3.2-not applicable (NA)] months, 1.7 (95% CI 1.4-NA) months, and 10.6 (95% CI 8.3-NA) months, respectively. The median PFS for patients in cohort A with prior T-DM1 use was 10.4 (95% CI 2.7-NA) months. CONCLUSIONS: PIK3CA targeting with taselisib in combination with HER2-targeted therapies was associated with both promising efficacy and substantial toxicities.

Blockade of SIRPα-CD47 axis by anti-SIRPα antibody enhances anti-tumor activity of DXd antibody-drug conjugates.

Signal regulatory protein alpha (SIRPα) is an immune inhibitory receptor on myeloid cells including macrophages and dendritic cells, which binds to CD47, a ubiquitous self-associated molecule. SIRPα-CD47 interaction is exploited by cancer cells to suppress anti-tumor activity of myeloid cells, therefore emerging as a novel immune checkpoint for cancer immunotherapy. In blood cancer, several SIRPα-CD47 blockers have shown encouraging monotherapy activity. However, the anti-tumor activity of SIRPα-CD47 blockers in solid tumors seems limited, suggesting the need for combination therapies to fully exploit the myeloid immune checkpoint in solid tumors. Here we tested whether combination of SIRPα-CD47 blocker with antibody-drug conjugate bearing a topoisomerase I inhibitor DXd (DXd-ADC) would enhance anti-tumor activity in solid tumors. To this end, DS-1103a, a newly developed anti-human SIRPα antibody (Ab), was assessed for the potential combination benefit with datopotamab deruxtecan (Dato-DXd) and trastuzumab deruxtecan (T-DXd), DXd-ADCs targeting human trophoblast cell-surface antigen 2 and human epidermal growth factor receptor 2, respectively. DS-1103a inhibited SIRPα-CD47 interaction and enhanced antibody-dependent cellular phagocytosis of Dato-DXd and T-DXd against human cancer cells. In a whole cancer cell vaccination model, vaccination with DXd-treated cancer cells led to activation of tumor-specific T cells when combined with an anti-mouse SIRPα (anti-mSIRPα) Ab, implying the benefit of combining DXd-ADCs with anti-SIRPα Ab on anti-tumor immunity. Furthermore, in syngeneic mouse models, both Dato-DXd and T-DXd combination with anti-mSIRPα Ab showed stronger anti-tumor activity over the monotherapies. Taken together, this study provides a preclinical rationale of novel therapies for solid tumors combining SIRPα-CD47 blockers with DXd-ADCs.

3D layered co-culture model enhances Trastuzumab Deruxtecan sensitivity and reveals the combined effect with G007-LK in HER2-positive non-small cell lung cancer.

Human epidermal growth factor receptor 2 (HER2) aberrations are observed in various cancers. In non-small cell lung cancer, genetic alterations activating HER2, mostly exon 20 insertion mutations, occur in approximately 2-4% of cases. Trastuzumab deruxtecan (T-DXd), a HER2-targeted antibody-drug conjugate has been approved as the first HER2-targeted drug for HER2-mutant lung cancer. However, some cases are not responsive to T-DXd and the primary resistant mechanism remains unclear. In this study, we assessed sensitivity to T-DXd in JFCR-007, a patient-derived HER2-mutant lung cancer cell line. Although JFCR-007 was sensitive to HER2 tyrosine kinase inhibitors, it showed resistance to T-DXd in attachment or spheroid conditions. Accordingly, we established a three-dimensional (3D) layered co-culture model of JFCR-007, where it exhibited a lumen-like structure and became sensitive to T-DXd. In addition, an in-house inhibitor library screening revealed that G007-LK, a tankyrase inhibitor, was effective when combined with T-DXd. G007-LK increased the cytotoxicity of topoisomerase-I inhibitor, DXd, a payload of T-DXd and SN-38. This combined effect was also observed in H2170, an HER2-amplified lung cancer cell line. These results suggest that the proposed 3D co-culture system may help in evaluating the efficacy of T-DXd and may recapitulate the tumor microenvironment.

Photoimmunotherapy of HER2-expressing Breast Cancer Cells.

BACKGROUND/AIM: Breast cancer (BC) is the most common malignant disease worldwide. Localized stages of BC can be successfully treated by surgery. However, local recurrence occurs in about 4-10% of patients, requiring systemic treatments that impair the patients' quality of life and shortens life expectancy. Therefore, new therapeutic options are needed, which can be used intraoperatively and contribute to the complete removal of residual tumor cells in the surgical area. In the present study, we describe a cysteine-modified variant of the anti-HER2 antibody trastuzumab, that was coupled to the silicon phthalocyanine photosensitizer dye WB692-CB1 for the photoimmunotherapy (PIT) of BC. MATERIALS AND METHODS: The cysteine modified trastuzumab variant was cloned and expressed in Expi293F cells. After purification via immobilized affinity chromatography, the antibody was coupled to the dye. Cell binding of the antibody and the antibody dye conjugate was measured by flow cytometry. After incubation of BC cells with the conjugate and activation of the dye by irradiation with red light, cell viability was determined. RESULTS: The antibody and the conjugate showed specific binding to HER2-expressing BC cells. Treatment of the HER2high BC cell line SK-BR-3 with the conjugate followed by irradiation with a red light dose of 32 J/cm2 led to complete cell killing within 24 h. CONCLUSION: Our novel antibody dye conjugate represents a promising candidate for intraoperative treatment of localized BC, aiming to eliminate residual tumor cells in the surgical area and potentially reduce local recurrence, thereby improving recovery prospects for BC patients.

In Vivo PET Imaging of 89Zr-Labeled Natural Killer Cells and the Modulating Effects of a Therapeutic Antibody.

Natural killer (NK) cells can kill cancer cells via antibody-dependent cell-mediated cytotoxicity (ADCC): a tumor-associated IgG antibody binds to the Fcγ receptor CD16 on NK cells via the antibody Fc region and activates the cytotoxic functions of the NK cell. Here, we used PET imaging to assess NK cell migration to human epidermal growth factor receptor 2 (HER2)-positive HCC1954 breast tumors, examining the influence of HER2-targeted trastuzumab antibody treatment on NK cell tumor accumulation. Methods: Human NK cells from healthy donors were expanded ex vivo and labeled with [89Zr]Zr-oxine. In vitro experiments compared the phenotypic markers, viability, proliferation, migration, degranulation, and ADCC behaviors of both labeled (89Zr-NK) and unlabeled NK cells. Female mice bearing orthotopic human breast HCC1954 tumors were administered 89Zr-NK cells alongside trastuzumab treatment or a sham treatment and then scanned using PET/CT imaging over 7 d. Flow cytometry and γ-counting were used to analyze the presence of 89Zr-NK cells in liver and spleen tissues. Results: 89Zr cell radiolabeling yields measured 42.2% ± 8.0%. At an average specific activity of 16.7 ± 4.7 kBq/106 cells, 89Zr-NK cells retained phenotypic and functional characteristics including CD56 and CD16 expression, viability, migration, degranulation, and ADCC capabilities. In vivo PET/CT studies indicated predominant accumulation of 89Zr-NK cells in the liver and spleen. Ex vivo analyses of liver and spleen tissues indicated that the administered human 89Zr-NK cells retained their radioactivity in vivo and that 89Zr did not transfer to cells of murine soft tissues, thus validating this 89Zr PET method for NK cell tracking. Notably, 89Zr-NK cells migrated to HER2-positive tumors, both with and without trastuzumab treatment. Trastuzumab treatment was associated with an increased 89Zr-NK cell signal at days 1 and 3 after injection. Conclusion: In vitro, 89Zr-NK cells maintained key cellular and cytotoxic functions. In vivo, 89Zr-NK cells trafficked to HER2-postive tumors, with trastuzumab treatment correlating with enhanced 89Zr-NK infiltration. This study demonstrates the feasibility of using PET to image 89Zr-NK cell infiltration into solid tumors.

An optimised patient-derived explant platform for breast cancer reflects clinical responses to chemotherapy and antibody-directed therapy.

Breast Cancer is the most common cancer among women globally. Despite significant improvements in overall survival, many tumours are refractory to therapy and so novel approaches are required to improve patient outcomes. We have evaluated patient-derived explants (PDEs) as a novel preclinical platform for breast cancer (BC) and implemented cutting-edge digital pathology and multi-immunofluorescent approaches for investigating biomarker changes in both tumour and stromal areas at endpoint. Short-term culture of intact fragments of BCs as PDEs retained an intact immune microenvironment, and tumour architecture was augmented by the inclusion of autologous serum in the culture media. Cell death/proliferation responses to FET chemotherapy in BC-PDEs correlated significantly with BC patient progression-free survival (p = 0.012 and p = 0.0041, respectively) and cell death responses to the HER2 antibody therapy trastuzumab correlated significantly with HER2 status (p = 0.018). These studies show that the PDE platform combined with digital pathology is a robust preclinical approach for informing clinical responses to chemotherapy and antibody-directed therapies in breast cancer. Furthermore, since BC-PDEs retain an intact tumour architecture over the short-term, they facilitate the preclinical testing of anti-cancer agents targeting the tumour microenvironment.

A metabolic inhibitor blocks cellular fucosylation and enables production of afucosylated antibodies.

The fucosylation of glycoproteins regulates diverse physiological processes. Inhibitors that can control cellular levels of protein fucosylation have consequently emerged as being of high interest. One area where inhibitors of fucosylation have gained significant attention is in the production of afucosylated antibodies, which exhibit superior antibody-dependent cell cytotoxicity as compared to their fucosylated counterparts. Here, we describe ß-carbafucose, a fucose derivative in which the endocyclic ring oxygen is replaced by a methylene group, and show that it acts as a potent metabolic inhibitor within cells to antagonize protein fucosylation. ß-carbafucose is assimilated by the fucose salvage pathway to form GDP-carbafucose which, due to its being unable to form the oxocarbenium ion-like transition states used by fucosyltransferases, is an incompetent substrate for these enzymes. ß-carbafucose treatment of a CHO cell line used for high-level production of the therapeutic antibody Herceptin leads to dose-dependent reductions in core fucosylation without affecting cell growth or antibody production. Mass spectrometry analyses of the intact antibody and N-glycans show that ß-carbafucose is not incorporated into the antibody N-glycans at detectable levels. We expect that ß-carbafucose will serve as a useful research tool for the community and may find immediate application for the rapid production of afucosylated antibodies for therapeutic purposes.

Plant-Derived Anti-Human Epidermal Growth Factor Receptor 2 Antibody Suppresses Trastuzumab-Resistant Breast Cancer with Enhanced Nanoscale Binding.

Traditional monoclonal antibodies such as Trastuzumab encounter limitations when treating Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer, particularly in cases that develop resistance. This study introduces plant-derived anti-HER2 variable fragments of camelid heavy chain domain (VHH) fragment crystallizable region (Fc) KEDL(K) antibody as a potent alternative for overcoming these limitations. A variety of biophysical techniques, in vitro assays, and in vivo experiments uncover the antibody's nanoscale binding dynamics with transmembrane HER2 on living cells. Single-molecule force spectroscopy reveals the rapid formation of two robust bonds, exhibiting approximately 50 pN force resistance and bond lifetimes in the second range. The antibody demonstrates a specific affinity for HER2-positive breast cancer cells, including those that are Trastuzumab-resistant. Moreover, in immune-deficient mice, the plant-derived anti-HER2 VHH-FcK antibody exhibits superior antitumor activity, especially against tumors that are resistant to Trastuzumab. These findings underscore the plant-derived antibody's potential as an impactful immunotherapeutic strategy for treating Trastuzumab-resistant HER2-positive breast cancer.

Conditional Cell Penetration of Masked CPPs by an ADEPT-like Approach.

The intracellular delivery of cargos via cell penetrating peptides (CPPs) holds significant promise as a drug delivery vehicle, but a major issue is their lack of cell type specificity, which can lead to detrimental off-target effects. We use an ADEPT-like concept to introduce conditional and selective activation of cellular uptake by using the lysine-rich, cationic, and amphiphilic L17E peptide as a model CPP. By masking the lysine residues of the L17E peptide with enzyme-cleavable acetyl protecting groups, the delivery of the covalently conjugated fluorophore TAMRA to HeLa cells was diminished. Recovery of cellular uptake could be achieved by deacetylation of the masked acetylated L17E peptide using the NAD-dependent sirtuin 2 (SirT2) deacetylase in vitro. Finally, trastuzumab-SirT2 and anti-B7H3-SirT2 antibody-enzyme conjugates were generated for the conditional and selective delivery of a cryptophycin cytotoxin by the L17E peptide. While the masked peptide still demonstrated some cytotoxicity, selective cell killing mediated by the antibody-enzyme conjugates was observed.

YAP inhibition overcomes adaptive resistance in HER2-positive gastric cancer treated with trastuzumab via the AKT/mTOR and ERK/mTOR axis.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) is a heterogeneous GC subtype characterized by the overexpression of HER2. To date, few specific targeted therapies have demonstrated durable efficacy in HER2-positive GC patients, with resistance to trastuzumab typically emerging within 1 year. However, the mechanisms of resistance to trastuzumab remain incompletely understood, presenting a significant challenge to clinical practice. METHODS: In this study, we integrated genetic screening and bulk transcriptome and epigenomic profiling to define the mechanisms mediating adaptive resistance to HER2 inhibitors and identify potential effective therapeutic strategies for treating HER2-positive GCs. RESULTS: We revealed a potential association between adaptive resistance to trastuzumab in HER2-positive GC and the expression of YES-associated protein (YAP). Notably, our investigation revealed that long-term administration of trastuzumab triggers extensive chromatin remodeling and initiates YAP gene transcription in HER2-positive cells characterized by the initial inhibition and subsequent reactivation. Furthermore, treatment of HER2-positive GC cells and cell line-derived xenografts (CDX) models with YAP inhibitors in combination with trastuzumab was found to induce synergistic effects through the AKT/mTOR and ERK/mTOR pathways. CONCLUSION: These findings underscore the pivotal role of reactivated YAP and mTOR signaling pathways in the development of adaptive resistance to trastuzumab and may serve as a promising joint target to overcome resistance to trastuzumab.

Efficacy and safety of pyrotinib combined with albumin-bound paclitaxel as first-line treatment for HER2-positive metastatic breast cancer in patients previously treated with adjuvant and/or neoadjuvant trastuzumab therapy: The stage 1 results of a single-arm, phase 2 prospective clinical trial.

OBJECTIVE: It has been observed that the prognosis of patients with HER2-positive metastatic breast cancer has improved significantly with HER2-targeted agents. However, there is still a lack of evidence regarding first-line anti-HER2 treatment options for patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer. Besides, there are no reliable markers that can predict the efficacy of anti-HER2 treatment in these patients. METHODS: Patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer were enrolled. Pyrotinib plus albumin-bound paclitaxel were used as first-line treatment. The primary endpoint was the objective response rate (ORR). The safety profile was also assessed. In order to explore predictive biomarkers using Olink technology, blood samples were collected dynamically. RESULTS: From December 2019 to August 2023, the first stage of the study involved 27 eligible patients. It has not yet reached the median PFS despite the median follow-up being 17.8 months. Efficacy evaluation showed that the ORR was 92.6%, and the DCR was 100%. Adverse events of grade 3 or higher included diarrhoea (29.6%), leukopenia (11.1%), neutropenia (25.9%), oral mucositis (3.7%), and hand-foot syndrome (3.7%). Toll-like receptor 3 (TLR3) and Proto-oncogene tyrosine-protein kinase receptor (RET) were proteins with significant relevance to PFS in these patients. CONCLUSIONS: This study demonstrates that pyrotinib plus albumin-bound paclitaxel as a first-line treatment regimen shows good efficacy and manageable safety for patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer. Besides, a significant association was identified between the expression levels of TLR3 and RET and the PFS in patients.

Bioinformatics and In Vitro Study Reveal ERα as The Potential Target Gene of Honokiol to Enhance Trastuzumab Sensitivity in HER2+ Trastuzumab-Resistant Breast Cancer Cells.

Trastuzumab resistance presents a significant challenge in the treatment of HER2+ breast cancer, necessitating the investigation of combination therapies to overcome this resistance. Honokiol, a compound with broad anticancer activity, has shown promise in this regard. This study aims to discover the effect of honokiol in increasing trastuzumab sensitivity in HER2+ trastuzumab-resistant breast cancer cells HCC1954 and the underline mechanisms behind. A bioinformatics study performed to explore the most potential target hub gene for honokiol in HER2+ breast cancer. Honokiol, trastuzumab and combined treatment cytotoxicity activity was then evaluated in both parental HCC1954 and trastuzumab resistance (TR-HCC1954) cells using MTT assay. The expression levels of these hub genes were then analyzed using qRT-PCR and those that could not be analyzed were subjected to molecular docking to determine their potential. Honokiol showed a potent cytotoxicity activity with an IC50 of 41.05 µM and 69.61 µM in parental HCC1954 and TR-HCC1954 cell line respectively. Furthermore, the combination of honokiol and trastuzumab resulted in significant differences in cytotoxicity in TR-HCC1954 cells at specific concentrations. Molecular docking and the qRT-PCR showed that the potential ERα identified from the bioinformatics analysis was affected by the treatment. Our results show that honokiol has the potential to increase the sensitivity of trastuzumab in HER2+ trastuzumab resistant breast cancer cell line HCC1954 by affecting regulating estrogen receptor signaling. Further research is necessary to validate these findings.

Trastuzumab deruxtecan versus trastuzumab emtansine in HER2-positive metastatic breast cancer patients with brain metastases from the randomized DESTINY-Breast03 trial.

BACKGROUND: DESTINY-Breast03 is a randomized, multicenter, open-label, phase III study of trastuzumab deruxtecan (T-DXd) versus trastuzumab emtansine (T-DM1) in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC) previously treated with trastuzumab and a taxane. A statistically significant improvement in progression-free survival (PFS) versus T-DM1 was reported in the primary analysis. Here, we report exploratory efficacy data in patients with and without brain metastases (BMs) at baseline. PATIENTS AND METHODS: Patients were randomly assigned 1 : 1 to receive T-DXd 5.4 mg/kg or T-DM1 3.6 mg/kg. Patients with clinically inactive/asymptomatic BMs were eligible. Lesions were measured as per modified RECIST, version 1.1. Outcomes included PFS by blinded independent central review (BICR), objective response rate (ORR), and intracranial ORR as per BICR. RESULTS: As of 21 May 2021, 43/261 patients randomized to T-DXd and 39/263 patients randomized to T-DM1 had BMs at baseline, as per investigator assessment. Among patients with baseline BMs, 20/43 in the T-DXd arm and 19/39 in the T-DM1 arm had not received prior local BM treatment. For patients with BMs, median PFS was 15.0 months [95% confidence interval (CI) 12.5-22.2 months] for T-DXd versus 3.0 months (95% CI 2.8-5.8 months) for T-DM1; hazard ratio (HR) 0.25 (95% CI 0.13-0.45). For patients without BMs, median PFS was not reached (95% CI 22.4 months-not estimable) for T-DXd versus 7.1 months (95% CI 5.6-9.7 months) for T-DM1; HR 0.30 (95% CI 0.22-0.40). Confirmed systemic ORR was 67.4% for T-DXd versus 20.5% for T-DM1 and 82.1% for T-DXd versus 36.6% for T-DM1 for patients with and without BMs, respectively. Intracranial ORR was 65.7% with T-DXd versus 34.3% with T-DM1. CONCLUSIONS: Patients with HER2-positive mBC whose disease progressed after trastuzumab and a taxane achieved a substantial benefit from treatment with T-DXd compared with T-DM1, including those with baseline BMs.

Early therapy evaluation of intra-arterial trastuzumab injection in a human breast cancer xenograft model using multiparametric MR imaging.

PURPOSE: To investigate the treatment efficacy of intra-arterial (IA) trastuzumab treatment using multiparametric magnetic resonance imaging (MRI) in a human breast cancer xenograft model. MATERIALS AND METHODS: Human breast cancer cells (BT474) were stereotaxically injected into the brains of nude mice to obtain a xenograft model. The mice were divided into four groups and subjected to different treatments (IA treatment [IA-T], intravenous treatment [IV-T], IA saline injection [IA-S], and the sham control group). MRI was performed before and at 7 and 14 d after treatment to assess the efficacy of the treatment. The tumor volume, apparent diffusion coefficient (ADC), and dynamic contrast-enhanced (DCE) MRI parameters (Ktrans, Kep, Ve, and Vp) were measured. RESULTS: Tumor volumes in the IA-T group at 14 d after treatment were significantly lower than those in the IV-T group (13.1 mm3 [interquartile range 8.48-16.05] vs. 25.69 mm3 [IQR 20.39-30.29], p = 0.005), control group (IA-S, 33.83 mm3 [IQR 32.00-36.30], p<0.01), and sham control (39.71 mm3 [IQR 26.60-48.26], p <0.001). The ADC value in the IA-T group was higher than that in the control groups (IA-T, 7.62 [IQR 7.23-8.20] vs. IA-S, 6.77 [IQR 6.48-6.87], p = 0.044 and vs. sham control, 6.89 [IQR 4.93-7.48], p = 0.004). Ktrans was significantly decreased following the treatment compared to that in the control groups (p = 0.002 and p<0.001 for vs. IA-S and sham control, respectively). Tumor growth was decreased in the IV-T group compared to that in the sham control group (25.69 mm3 [IQR 20.39-30.29] vs. 39.71 mm3 [IQR 26.60-48.26], p = 0.27); there was no significant change in the MRI parameters. CONCLUSION: IA treatment with trastuzumab potentially affects the early response to treatment, including decreased tumor growth and decrease of Ktrans, in a preclinical brain tumor model.

Quantifying Antibody-Dependent Cellular Cytotoxicity in a Tumor Spheroid Model: Application for Drug Discovery.

Monoclonal antibody-based immunotherapy targeting tumor antigens is now a mainstay of cancer treatment. One of the clinically relevant mechanisms of action of the antibodies is antibody-dependent cellular cytotoxicity (ADCC), where the antibody binds to the cancer cells and engages the cellular component of the immune system, e.g., natural killer (NK) cells, to kill the tumor cells. The effectiveness of these therapies could be improved by identifying adjuvant compounds that increase the sensitivity of the cancer cells or the potency of the immune cells. In addition, undiscovered drug interactions in cancer patients co-medicated for previous conditions or cancer-associated symptoms may determine the success of the antibody therapy; therefore, such unwanted drug interactions need to be eliminated. With these goals in mind, we created a cancer ADCC model and describe here a simple protocol to find ADCC-modulating drugs. Since 3D models such as cancer cell spheroids are superior to 2D cultures in predicting in vivo responses of tumors to anticancer therapies, spheroid co-cultures of EGFP-expressing HER2+ JIMT-1 breast cancer cells and the NK92.CD16 cell lines were set up and induced with Trastuzumab, a monoclonal antibody clinically approved against HER2-positive breast cancer. JIMT-1 spheroids were allowed to form in cell-repellent U-bottom 96-well plates. On day 3, NK cells and Trastuzumab were added. The spheroids were then stained with Annexin V-Alexa 647 to measure apoptotic cell death, which was quantitated in the peripheral zone of the spheroids with an automated microscope. The applicability of our assay to identify ADCC-modulating molecules is demonstrated by showing that Sunitinib, a receptor tyrosine kinase inhibitor approved by the FDA against metastatic cancer, almost completely abolishes ADCC. The generation of the spheroids and image acquisition and analysis pipelines are compatible with high-throughput screening for ADCC-modulating compounds in cancer cell spheroids.

Characterization of Potential Target Genes of Borneol in Increasing Trastuzumab Sensitivity in HER2+ Trastuzumab-Resistant Breast Cancer: Bioinformatics and In Vitro Studies.

OBJECTIVE: The long-term use of trastuzumab (TRZ), a therapeutic agent for human epidermal growth factor receptor 2 (HER2)+ breast cancer subtype (HER2+ BC), induces resistance. Borneol (BOR) exerts anticancer effects on various types of cancer. However, its anticancer effect on HER2+ BC remains unknown. This study aimed to determine the potential target genes of BOR and its effect on overcoming the resistance of HER2+ BC to TRZ. METHODS: The hub gene of  BOR's potential target on HER2+ BC cells was determined via a bioinformatics approach. Resistant HCC1954 cells (HCC1954-TR) were obtained through repeated inducement of HCC1954 cancer cells with TRZ. The cells were then subjected to cytotoxic tests involving single compounds and their combinations. Then, the hub gene expression was determined using quantitative reverse-transcription polymerase chain reaction. The interaction between BOR and selected proteins was measured through molecular docking. RESULTS: Hub genes IL6, TNF, ESR1, IL1B, CYP19A1, AR, NR3C1, RELA, CYP17A1, and GPT were obtained via a bioinformatics approach. HCC1954-TR cells were successfully established. The TRZ-BOR combination treatment of parental HCC1954 (400 µg/mL and 25 µM) and HCC1954-TR (800 µg/mL and 100 µM) yielded considerably better results compared with BOR or TRZ alone. The expressions of AR, GPT, and ESR1 under the TRZ-BOR combination were notably different compared with those under single exposure. The molecular docking study of CYP19A1, CYP17A1, NR3C1, and IL-1ß highlighted the potential interaction between BOR and such proteins. CONCLUSION: BOR improved the cytotoxic effects of TRZ on HCC1954 and HCC1954-TR cell lines, where it specifically targets AR, ESR1, and GPT genes. In addition, the BOR effect, which counteracted the resistance of HCC1954-TR cells to TRZ, was mediated by genes CYP19A1, CYP17A1, NR3C1, IL-1, and RELA. However, additional research is required to validate their role in BOR activity to circumvent the resistance of HER2+ BC to TRZ.