HER2 signaling modulates the equilibrium between pro- and antiangiogenic factors via distinct pathways: implications for HER2-targeted antibody therapy

Neuro-ophthalmic complications of modern anti-cancer drugs

PURPOSE

Targeted cancer therapies have been responsible for a dramatic shift in treatment strategies for cancer, and the number of drugs, classes, and indications are continually growing. Neuro-ophthalmic complications of these medications are an uncommon but important subset of adverse events which profoundly impact vision. This review aims to collate studies and reports of known neuro-ophthalmic complications of targeted therapies and describe their management.

METHODS

The anti-cancer drugs included in the review were any drugs targeting specific molecules involved in the cancer disease process. PubMed, EMBASE, and Web of Science were searched using the generic names of each drug and keywords of neuro-ophthalmic conditions. The prescribing information published by the US Food and Drug Administration (FDA) for each drug was also reviewed.

RESULTS

Several classes of targeted anti-cancer drugs were found to cause neuro-ophthalmic adverse effects. Immune checkpoint inhibitors are responsible for a raft of immune-related adverse events such as optic neuritis, ischemic optic neuropathy, PRES, and myasthenia gravis. Therapies with anti-VEGF activity can provoke posterior reversible leukoencephalopathy, which commonly presents with visual loss and can be fatal if not treated promptly. Inhibitors of BCR-ABL1, VEGF, ALK, and proteasomes have all been linked to optic nerve disorders which can have debilitating consequences for vision.

CONCLUSION

The neuro-ophthalmic complications of modern anti-cancer drugs can limit or necessitate the withdrawal of these life-prolonging medications. Ophthalmologists should be alert for neuro-ophthalmic complications in these medications to facilitate prompt diagnosis and treatment and reduce the risk of severe and permanent consequences.

Multiparametric MR characterization for human epithelial growth factor receptor 2 expression in bladder cancer: an exploratory study

PURPOSE

To investigate the application value of multiparametric MRI in evaluating the expression status of human epithelial growth factor receptor 2 (HER2) in bladder cancer (BCa).

METHODS

From April 2021 to July 2023, preoperative imaging manifestations of 90 patients with pathologically confirmed BCa were retrospectively collected and analyzed. All patients underwent multiparametric MRI including synthetic MRI, DWI, from which the T1, T2, proton density (PD) and apparent diffusion coefficient (ADC) values were obtained. The clinical and imaging characteristics as well as quantitative parameters (T1, T2, PD and ADC values) between HER2-positive and -negative BCa were compared using student t test and chi-square test. The diagnostic efficacy of parameters in predicting HER2 expression status was evaluated by calculating the area under ROC curve (AUC).

RESULTS

In total, 76 patients (mean age, 63.59 years ± 12.84 [SD]; 55 men) were included: 51 with HER2-negative and 25 with HER2-positive BCa. HER2-positive group demonstrated significantly higher ADC, T1, and T2 values than HER2-negative group (all P < 0.05). The combination of ADC values and tumor grade yielded the best diagnostic performance in evaluating HER2 expression level with an AUC of 0.864.

CONCLUSION

The multiparametric MR characterization can accurately evaluate the HER2 expression status in BCa, which may further guide the determination of individualized anti-HER2 targeted therapy strategies.

Plasma THBS1 as a predictive biomarker for poor prognosis and brain metastasis in patients with HER2-enriched breast cancer

BACKGROUND

Thrombospondin-1 (THBS1) is a secretory adhesive glycoprotein involved in the progression of multiple malignancies, including breast cancer. However, the clinical significance and prognostic role of plasma THBS1 in breast cancer have yet to be clarified.

METHODS

Plasma THBS1 levels in 627 breast cancer patients were analyzed by enzyme-linked immunosorbent assay. Bone marrow blood was drawn from the anterior/posterior superior iliac spine to detect the presence of disseminated tumor cells (DTCs). The effects of plasma THBS1 on the clinicopathological characteristics and survival prediction of breast cancer patients were explored.

RESULTS

Plasma THBS1 did not correlate with overall survival, breast cancer-specific survival (BCSS), and distant disease-free survival (DDFS) in the entire breast cancer cohort. Notably, HER2-enriched patients with high-plasma THBS1 levels had significantly shorter BCSS (P = 0.027) and DDFS (P = 0.011) than those with low levels. Multivariate analyses revealed that plasma THBS1 was an independent prognostic marker of BCSS (P = 0.026) and DDFS (P = 0.007) in HER2-enriched patients. THBS1 levels were 24% higher in positive DTC patients than in negative DTC patients (P = 0.031), and high levels were significantly associated with poor BCSS in positive DTC patients (HR 2.08, 95% CI 1.17-3.71; P = 0.019). Moreover, high-plasma THBS1 levels were specifically associated with an increased occurrence of brain metastasis in HER2-enriched patients (P = 0.041).

CONCLUSION

These findings suggest that plasma THBS1 may be serving as an unfavorable prognosis predictor for HER2-enriched breast cancer and justifies the need for further research.

Metronomic chemotherapy and drug repurposing: A paradigm shift in oncology

Cancer represents a significant global health and economic burden due to its high mortality rates. While effective in some instances, traditional chemotherapy often falls short of entirely eradicating various types of cancer. It can cause severe side effects due to harm to healthy cells. Two therapeutic approaches have risen to the forefront to address these limitations: metronomic chemotherapy (MCT) and drug repurposing. Metronomic chemotherapy is an innovative approach that breaks from traditional models. It involves the administration of chemotherapeutic regimens at lower doses, without long drug-free intervals that have previously been a hallmark of such treatments. This method offers a significant reduction in side effects and improved disease management. Simultaneously, drug repurposing has gained considerable attraction in cancer treatment. This approach involves utilizing existing drugs, initially developed for other therapeutic purposes, as potential cancer treatments. The application of known drugs in a new context accelerates the timeline from laboratory to patient due to pre-existing safety and dosage data. The intersection of these two strategies gives rise to a novel therapeutic approach named 'Metronomics.' This approach encapsulates the benefits of both MCT and drug repurposing, leading to reduced toxicity, potential for oral administration, improved patient quality of life, accelerated clinical implementation, and enhanced affordability. Numerous clinical studies have endorsed the efficacy of metronomic chemotherapy with tolerable side effects, underlining the potential of Metronomics in better cancer management, particularly in low- and middle-income countries. This review underscores the benefits and applications of metronomic chemotherapy and drug repurposing, specifically in the context of breast cancer, showcasing the promising results of pre-clinical and clinical studies. However, we acknowledge the necessity of additional clinical investigations to definitively establish the role of metronomic chemotherapy in conjunction with other treatments in comprehensive cancer management.

National Cancer Institute Experience in Micro-invasive Breast Carcinoma Treatment and Outcome

AbstractBackground: Significant relationship between breast cancer immunophenotype and risk of recurrence either local and/or distant may help determine which patients might benefit more from axillary staging and whether axillary staging is warranted in all cases or not. Patients with microinvasive carcinoma can present with axillary LN. metastasis, with incidence ranges from 0% to 20% . Thus, sentinel node biopsies are considered for patients with microinvasive carcinoma. The role of axillary staging in MIBC is not well defined, with the rate of axillary L.N. metastases ranging 0–11 %. Current studies focus on the clinical characteristics of MIBC. However, only a few studies have evaluated the survival and treatment, especially adjuvant chemotherapy after surgery, for patients with MIBC.Methods: This is a retrospective study of 139 cases diagnosed with microinvasive breast carcinoma from 2011 to 2015 who were identified in the National Cancer Institute, Cairo University. The pathologic database of our hospital was searched to identify patients with a pathologic diagnosis of MIBC on surgical specimens. The clinical features, sonographic and mammographic images and pathology records were reviewed.Results: There is increased incidence of MIBC over the past decade. Patients with MIBC were managed surgically with BCS. MIBC have the good prognosis. However, patients who are negative hormonal receptors have relatively substantial risk of relapse within the first 5 years after surgical operation. Adjuvant chemotherapy can only improve the outcomes of patients with negative hormonal receptors. Further studies with prolonged follow-up of large cohort are warranted to assess the prognostic significance and treatment of this lesion.Keywords: MIBC, CIS, DCIS, BC

Downregulation of miR-375 contributes to ERBB2-mediated VEGFA overexpression in esophageal cancer

Esophageal cancer (EC) is a lethal cancer with an extremely aggressive nature and poor survival rate. However, the molecular mechanisms driving the occurrence and progression of EC are not well understood. MicroRNAs (miRNAs) are small RNA molecules that regulate the expression of protein-coding genes. miRNA-mediated gene regulation plays an important role in EC. By cross-referencing studies from NCBI, we found that microRNA-375 (miR-375) is one of the most frequently downregulated miRNAs in EC. We assessed expression of miR-375 in EC cell lines and primary EC tissues and their matched normal tissues. We found significant downregulation of miR-375 in both cell lines and EC tissues. Forced expression of miR-375 attenuated EC cell proliferation and invasion. Human epidermal growth factor receptor 2 (HER2, ERBB2), a known proto-oncogene, was identified here as one of the potential target genes of miR-375. Ectopic expression of miR-375 significantly suppressed the expression of ERBB2 and subsequently downregulated one of its target genes, vascular endothelial growth factor A (VEGFA), which is related to cancer invasion and metastasis. These findings suggest that miR-375 acts as a tumor suppressor by blocking the ERBB2/VEGFA pathway with the potential to modulate the occurrence and/ or progression of EC.

Breast ductal Carcinoma in situ associated with microinvasion induces immunological response and predicts ipsilateral invasive recurrence

Although microinvasion (Mi) is often thought to be an interim stage between ductal carcinoma in situ (DCIS) and established invasive ductal carcinoma, survival outcomes and biological behaviour of DCIS-Mi are still poorly understood. This study investigated the potential influence of Mi on disease-free survival (DFS) and assessed its correlations with clinicopathological parameters, prognosis, molecular, and immune markers. CD4, CD8, forkhead box P3 (FOXP3), CD68, CD163, programmed cell death protein 1 (PD-1), and its ligand (PD-L1) expression in pure DCIS and DCIS-Mi, from a cohort of 198 patients, were determined by immunohistochemistry. DFS, clinicopathological parameters, immune markers, and biomarker expression were correlated with presence of Mi. Twelve out of 198 DCIS cases were associated with Mi. DCIS-Mi was significantly linked with ipsilateral invasive recurrence (p = 0.032). Kaplan-Meier analysis revealed that DCIS-Mi had worse DFS for ipsilateral invasive recurrence (p = 0.011) and this was affirmed by multivariate Cox regression analysis (95% CI 1.181-9.010, HR = 3.262, p = 0.023). DCIS-Mi was associated with higher densities of immune infiltrates positive for CD4 (p = 0.037), FOXP3 (p = 0.037), CD163 (p = 0.01), and PD-L1 (p = 0.015). This study demonstrated that DCIS-Mi was correlated with high densities of immune infiltrates and predicted ipsilateral invasive recurrence.

Trastuzumab: More than a Guide in HER2-Positive Cancer Nanomedicine

HER2 overexpression, which occurs in a fifth of diagnosed breast cancers as well as in other types of solid tumors, has been traditionally linked to greater aggressiveness. Nevertheless, the clinical introduction of trastuzumab has helped to improve HER2-positive patients' outcomes. As a consequence, nanotechnology has taken advantage of the beneficial effects of the administration of this antibody and has employed it to develop HER2-targeting nanomedicines with promising therapeutic activity and limited toxicity. In this review, the molecular pathways that could be responsible for trastuzumab antitumor activity will be briefly summarized. In addition, since the conjugation strategies that are followed to develop targeting nanomedicines are essential to maintaining their efficacy and tolerability, the ones most employed to decorate drug-loaded nanoparticles and liposomes with trastuzumab will be discussed here. Thus, the advantages and disadvantages of performing this trastuzumab conjugation through adsorption or covalent bindings (through carbodiimide, maleimide, and click-chemistry) will be described, and several examples of targeting nanovehicles developed following these strategies will be commented on. Moreover, conjugation methods employed to synthesized trastuzumab-based antibody drug conjugates (ADCs), among which T-DM1 is well known, will be also examined. Finally, although trastuzumab-decorated nanoparticles and liposomes and trastuzumab-based ADCs have proven to have better selectivity and efficacy than loaded drugs, trastuzumab administration is sometimes related to side toxicities and the apparition of resistances. For this reason also, this review focuses at last on the important role that newer antibodies and peptides are acquiring these days in the development of HER2-targeting nanomedicines.

Overcoming trastuzumab resistance in HER2-positive breast cancer using combination therapy

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) comprises around 20-30% of all BC subtypes and is correlated with poor prognosis. For many years, trastuzumab, a monoclonal antibody, has been used to inhibit the HER2 activity. Though, the main resistance to trastuzumab has challenged the use of this drug in the management of HER2-positive BC. Therefore, the determination of resistance mechanisms and the incorporation of new agents may lead to the development of a better blockade of the HER family receptor signaling. During the last few years, some therapeutic drugs have been developed for treating patients with trastuzumab-resistant HER2-positive BC that have more effective influences in the management of this condition. In this regard, the present study aimed at reviewing the mechanisms of trastuzumab resistance and the innovative therapies that have been investigated in trastuzumab-resistant HER2-positive BC subjects.

Postoperative administration of ketorolac averts morphine-induced angiogenesis and metastasis in triple-negative breast cancer

AIMS

Opioids (i.e. morphine) were found to induce triple negative breast cancer (TNBC) metastasis while nonsteroidal anti-inflammatory drugs (i.e. ketolorac) were associated with decreased metastasis in TNBC. These contradictory findings demand clarification on the effect of postoperative morphine and ketorolac on TNBC metastasis.

MATERIALS AND METHODS

TNBC xenograft mice were established using MDA-MB-231 cells. When tumors reached ~100 mm³, the primary tumor was resected. Mice were then randomly assigned to four groups (n = 14): (i) saline, (ii) morphine (10 mg kg^-1) (iii) morphine + ketorolac (10 mg kg^-1 of morphine and 20 mg kg^-1 of ketorolac) (iv) ketorolac (20 mg kg^-1); administrated for three consecutive days after resection. Three weeks after resection, the number of lung metastases was measured. Microvessel density, thrombospondin-1 (TSP-1) and c-Myc expression in recurrent tumors were determined. To elucidate the above phenomenon in vitro, MDA-MB-231 cells were treated according to the regiment above; with or without supplementation of an AKT inhibitor to determine the activation of PI3K/AKT/c-Myc pathway.

KEY FINDINGS

In mice, morphine promoted TNBC metastasis and angiogenesis, decreased TSP-1 expression and increased c-Myc expression, while co-administration of ketorolac significantly reversed the phenotypes above (p < .05). Mechanistically, morphine inhibited TSP-1 secretion by activating PI3K/AKT/c-Myc pathway (p < .05), while ketorolac promoted TSP-1 secretion (p < .05) by suppressing PI3K/AKT/c-Myc pathway.

SIGNIFICANCE

Our study indicated that morphine enhanced TNBC metastasis and angiogenesis while ketorolac suppressed this effect. Mechanistically, this may be related to the enhancement of TSP-1 synthesis after ketorolac administration which further de-activated PI3K/AKT/c-Myc pathway.

A new anti-HER2 antibody that enhances the anti-tumor efficacy of trastuzumab and pertuzumab with a distinct mechanism of action

The majority of patients with metastatic breast cancer who are treated with the anti-HER2 monoclonal antibody, trastuzumab, generally develop resistance to the drug within a year after initiation of the treatment. Here we describe a new anti-HER2 humanized monoclonal antibody, 19H6-Hu, which binds to HER2 extracellular domain (ECD) with high affinity and inhibits proliferation of multiple HER2-overexpressing cancer cell lines as a single agent or in combination with trastuzumab. 19H6-Hu binds to the domain III in proximity to the domain IV of HER2 ECD, which differs from trastuzumab and pertuzumab. 19H6-Hu in combination with trastuzumab was more effective at blocking phosphorylation of ERK1/2, AKT(S473)and HER2 (Y1248) in HER2-positive cancer cells compared to trastuzumab alone or in combination with pertuzumab. Combination of three antibodies, 19H6-Hu, inetetamab (a trastuzumab analog) and pertuzumab exhibited much stronger inhibition of large NCI-N87 tumor xenografts (>400mm³) than the current standard of care, inetetamab (trastuzumab) plus Docetaxel (DTX), as well as the combination of 19H6-Hu, inetetamab and DTX. Our results highlight the functional variability of HER2 domains and provide a new insight into the design of HER2-targeting agents.

Tumor progression-dependent angiogenesis in gastric cancer and its potential application

Despite improvements in the early diagnosis, prognosis and therapeutic strategies for gastric cancer (GC), human GC remains one of the most frequently diagnosed malignant tumors in the world, and the survival rate of GC patients remains very poor. Thus, a suitable therapeutic strategy for GC is important for prolonging survival. Both tumor cells themselves and the tumor microenvironment play an important role in tumorigenesis, including angiogenesis, inflammation, immunosuppression and metastasis. Importantly, these cells contribute to gastric carcinogenesis by altering the angiogenic phenotype switch. The development, relapse and spreading of tumors depend on new vessels that provide the nutrition, growth factors and oxygen required for continuous tumor growth. Therefore, a state of tumor dormancy could be induced by blocking tumor-associated angiogenesis. Recently, several antiangiogenic agents have been identified, and their potential for the clinical management of GC has been tested. Here, we provide an up-to-date summary of angiogenesis and the angiogenic factors associated with tumor progression in GC. We also review antiangiogenic agents with a focus on the anti-vascular endothelial growth factor receptor (VEGFR)-mediated pathway for endothelial cell growth and their angiogenesis ability in GC. However, most antiangiogenic agents have reported no benefit to overall survival (OS) compared to chemotherapy alone in local or advanced GC. In phase III clinical trials, only ramucirumab (anti-VEGFR blocker) and apatinib (VEGFR-TKI blocker) have reported an improved median overall response rate and prolonged OS and progression-free survival outcomes as a 2nd-line agent combined with chemotherapy treatment in advanced GC. By providing insights into the molecular mechanisms of angiogenesis associated with tumor progression in GC, this review will hopefully aid the optimization of antiangiogenesis strategies for GC therapy in combination with chemotherapy and adjuvant treatment.

Prognostic and therapeutic role of HER2 expression in micropapillary carcinoma of the bladder

Micropapillary carcinoma of the bladder (MPBC) is a variant type of infiltrating urothelial carcinoma, which portends a poor biological behavior in terms of disease stage at first diagnosis and clinical outcome; its peculiar morphology raises issues concerning the ability of tumor detection by imaging techniques and proper biopsy procedure, and the appropriate treatment for non-muscle infiltrating and muscle-infiltrating MPBC remains a matter of debate. On the basis of its established prognostic and therapeutic role in breast and gastro-esophageal cancer in the first instance, the human epidermal growth factor receptor-2 (HER2) has been investigated in selected case series of MPBC over the last 10 years. The aim of the present review was to summarize the existing evidence on HER2 status in MPBC, and to discuss its present and future utility in risk assessment and treatment choice of this uncommon, yet aggressive, disease.

Mechanism of action of the trastuzumab biosimilar CT-P6

Objectives: Therapeutic monoclonal antibody biosimilars are expected to help reduce the sizeable economic burden of targeted treatments. Trastuzumab (Herceptin®), a recombinant humanized monoclonal antibody that binds to the extracellular domain of HER2, is approved for use in HER2-overexpressing breast cancer (in both the adjuvant and metastatic settings) and HER2-positive gastric cancer. CT-P6 (Herzuma®) is a biosimilar of trastuzumab, designed to bind with high affinity and specificity to the same HER2 epitope as the reference product. We investigated whether CT-P6 exerts its effects through the same mechanism of action as trastuzumab. Methods: The mechanism of action of CT-P6 and trastuzumab, both as monotherapy and in combination with paclitaxel or pertuzumab, was compared in HER2-overexpressing breast cancer and gastric cancer cell models. Results: We confirmed that CT-P6 functions in a manner similar to trastuzumab by binding to the HER2 receptor, which is central to the effects of trastuzumab in all indications. Conclusions: Collectively, the results of this study show that the mechanisms of action of CT-P6 and trastuzumab are similar in HER2-positive breast cancer and gastric cancer models and, therefore, CT-P6 can be expected to perform similarly in the clinical setting.

Co-Expression of VEGF and IL-6 Family Cytokines is Associated with Decreased Survival in HER2 Negative Breast Cancer Patients: Subtype-Specific IL-6 Family Cytokine-Mediated VEGF Secretion

Breast cancer cell-response to inflammatory cytokines such as interleukin-6 (IL-6) and oncostatin M (OSM) may affect the course of clinical disease in a cancer subtype-dependent manner. Furthermore, vascular endothelial growth factor A (VEGF) secretion induced by IL-6 and OSM may also be subtype-dependent. Utilizing datasets from Oncomine, we show that poor survival of invasive ductal carcinoma (IDC) breast cancer patients is correlated with both high VEGF expression and high cytokine or cytokine receptor expression in tumors. Importantly, epidermal growth factor receptor-negative (HER2-), but not HER2-positive (HER2+), patient survival is significantly lower with high tumor co-expression of VEGF and OSM, OSMRβ, IL-6, or IL-6Rα compared to low co-expression. Furthermore, assessment of HER2- breast cancer cells in vitro identified unique signaling differences regulating cytokine-induced VEGF secretion. The levels of VEGF secretion were analyzed by ELISA with siRNAs for hypoxia inducible factor 1 α (HIF1α) and signal transducer and activator of transcription 3 (STAT3). Specifically, we found that estrogen receptor-negative (ER-) MDA-MB-231 cells respond only to OSM through STAT3 signaling, while ER+ T47D cells respond to both OSM and IL-6, though to IL-6 to a lesser extent. Additionally, in the ER+ T47D cells, OSM signals through both STAT3 and HIF1α. These results highlight that the survival of breast cancer patients with high co-expression of VEGF and IL-6 family cytokines is dependent on breast cancer subtype. Thus, the heterogeneity of human breast cancer in relation to IL-6 family cytokines and VEGF may have important implications in clinical treatment options, disease progression, and ultimately patient prognosis.

Phase 1b Study of Trebananib Plus Paclitaxel and Trastuzumab in Patients With HER2-Positive Locally Recurrent or Metastatic Breast Cancer

INTRODUCTION

Trebananib, a peptide-Fc fusion protein, blocks angiogenesis by inhibiting binding of angiopoietin-1/2 to the receptor tyrosine kinase Tie2. Trebananib plus trastuzumab and paclitaxel was evaluated in human epidermal growth factor receptor 2-positive breast cancer in an open-label phase 1b clinical study.

PATIENTS AND METHODS

Women with human epidermal growth factor receptor 2-positive breast cancer received weekly paclitaxel (80 mg/m²), trastuzumab (8 mg/m² then 6 mg/kg every 3 weeks), and intravenous trebananib (10 mg/kg or 30 mg/kg weekly) beginning week 2. The primary end point was the incidence of dose-limiting toxicities. Secondary end points included incidence of adverse events (AEs), pharmacokinetics, and tumor response (objective response and duration of response).

RESULTS

Forty women were enrolled; 2 experienced dose-limiting toxicities (grade 3 ocular transient ischemic attack [10 mg/kg cohort] and grade 3 elevation in γ-glutamyl transferase [30 mg/kg cohort]). The most common treatment-emergent AEs were peripheral edema (n = 28), diarrhea (n = 27), alopecia (n = 26), fatigue (n = 24), and nausea (n = 24). Maximum observed concentration and area under the concentration-time curve increased proportionally with the trebananib dose. Objective response was confirmed in 31 patients. In the 10 mg/kg cohort, 16 patients (80%) experienced partial response, and none experienced complete response. In the 30 mg/kg cohort, 12 patients (71%) experienced partial response and 3 (18%) experienced complete response. Median (95% confidence interval) duration of response in the 10 and 30 mg/kg cohorts was 12.6 (4.3-20.2) and 16.6 (8.2-not estimable) months, respectively.

CONCLUSION

This phase 1b study showed that trebananib was tolerated with manageable AEs at a dose up to 30 mg/kg weekly. Trebananib demonstrated anticancer activity, as indicated by objective response and duration of response.

Mechanisms Underlying the Action and Synergism of Trastuzumab and Pertuzumab in Targeting HER2-Positive Breast Cancer

Human epidermal growth factor receptor (HER) 2 (HER2) is overexpressed in 20⁻30% of breast cancers. HER2 is a preferred target for treating HER2-positive breast cancer. Trastuzumab and pertuzumab are two HER2-targeted monoclonal antibodies approved by the Food and Drug Administration (FDA) to use as adjuvant therapy in combination with docetaxel to treat metastatic HER2-positive breast cancer. Adding the monoclonal antibodies to treatment regimen has changed the paradigm for treatment of HER2-positive breast cancer. Despite improving outcomes, the percentage of the patients who benefit from the treatment is still low. Continued research and development of novel agents and strategies of drug combinations is needed. A thorough understanding of the molecular mechanisms underlying the action and synergism of trastuzumab and pertuzumab is essential for moving forward to achieve high efficacy in treating HER2-positive breast cancer. This review examined and analyzed findings and hypotheses regarding the action and synergism of trastuzumab and pertuzumab and proposed a model of synergism based on available information.

Current Targeted Therapies in HER2-Positive Gastric Adenocarcinoma

Gastric cancer is one of the most common types of cancer in the world, usually diagnosed at an advanced stage. Despite the advances in specific anticancer agents' development, the survival rates remain modest, even in early stages. In 15%-20% of cases, the human epidermal growth factor receptor 2 (HER2) overexpression was identified. We conducted a general review to summarize the progress that has been made in the targeted treatment of HER2-positive esogastric junction or gastric adenocarcinoma. According to our findings, trastuzumab is the only validated anti-HER2 agent in locally advanced or metastatic disease and its adjuvant effectiveness is assessed in a RTOG phase III study. In a previously treated advanced disease, the maytansine derivate TDM 1 failed to be approved as a second-line regimen, and the tyrosine kinase inhibitor, lapatinib, shows modest results. The antiangiogenics have not been analyzed in specific populations and targeting the mesenchymal-epithelial transition factor (MET) receptor, overexpressed in up to 46% of the advanced disease, seems encouraging. Regarding the checkpoint inhibitors, based on KEYNOTE 059 multilevel ongoing trial, stratified according to the HER2 and programmed death-ligand (PD-L) 1 status, pembrolizumab was approved for third-line treatment of gastric or gastroesophageal junction adenocarcinoma.

Microinvasive Carcinoma versus Ductal Carcinoma In Situ: A Comparison of Clinicopathological Features and Clinical Outcomes

PURPOSE

Although microinvasive carcinoma is distinct from ductal carcinoma in situ (DCIS), the clinical significance of microinvasion in DCIS remains elusive. The purpose of this study is to evaluate the clinicopathological features and clinical outcomes of microinvasive carcinoma compared with pure DCIS.

METHODS

We assessed 613 cases of DCIS and microinvasive carcinoma that were consecutively resected from 2003 to 2014 and analyzed clinicopathological variables, expression of standard biomarkers such as the estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), p53, and Ki-67, and tumor recurrence.

RESULTS

Among the 613 cases, 136 (22.2%) were classified as microinvasive carcinoma. Microinvasive carcinoma was significantly associated with DCIS with a large extent, high nuclear grade, necrosis, and comedotype architectural pattern. ER and PR expressions were dominantly observed in pure DCIS, whereas positive HER2 status, p53 overexpression, and high Ki-67 proliferation indices were more frequently observed in microinvasive carcinoma. Lymph node metastasis was found in only four cases of microinvasive carcinoma with multifocal microinvasion. In the multivariate analysis, DCIS with a large extent, comedo-type architectural pattern, and negative ER status were found to be independent predictors of microinvasion. During follow-up, 12 patients had ipsilateral breast recurrence, and no differences in recurrence rates were observed between patients with DCIS and those with microinvasive carcinoma. The triple-negative subtype was the only factor that was associated with tumor recurrence.

CONCLUSION

Microinvasive carcinomas are distinct from DCIS in terms of clinicopathological features and biomarker expressions but are similar to DCIS in terms of clinical outcomes. Our results suggest that microinvasive carcinoma can be treated and followed up as pure DCIS.

Trastuzumab-Resistant HER2+ Breast Cancer Cells Retain Sensitivity to Poly (ADP-Ribose) Polymerase (PARP) Inhibition

HER2-targeted therapies, such as trastuzumab, have increased the survival rates of HER2⁺ breast cancer patients. However, despite these therapies, many tumors eventually develop resistance to these therapies. Our lab previously reported an unexpected sensitivity of HER2⁺ breast cancer cells to poly (ADP-ribose) polymerase inhibitors (PARPi), agents that target homologous recombination (HR)-deficient tumors, independent of a DNA repair deficiency. In this study, we investigated whether HER2⁺ trastuzumab-resistant (TR) breast cancer cells were susceptible to PARPi and the mechanism behind PARPi induced cytotoxicity. We demonstrate that the PARPi ABT-888 (veliparib) decreased cell survival in vitro and tumor growth in vivo of HER2⁺ TR breast cancer cells. PARP-1 siRNA confirmed that cytotoxicity was due, in part, to PARP-1 inhibition. Furthermore, PARP-1 silencing had variable effects on the expression of several NF-κB-regulated genes. In particular, silencing PARP-1 inhibited NF-κB activity and reduced p65 binding at the IL8 promoter, which resulted in a decrease in IL8 mRNA and protein expression. Our results provide insight in the potential mechanism by which PARPi induces cytotoxicity in HER2⁺ breast cancer cells and support the testing of PARPi in patients with HER2⁺ breast cancer resistant to trastuzumab. Mol Cancer Ther; 17(5); 921-30. ©2018 AACR.

The effects of trastuzumab on HER2-mediated cell signaling in CHO cells expressing human HER2

BACKGROUND

Targeted therapy with trastuzumab has become a mainstay for HER2-positive breast cancer without a clear understanding of the mechanism of its action. While many mechanisms have been suggested for the action of trastuzumab, most of them are not substantiated by experimental data. It has been suggested that trastuzumab functions by inhibiting intracellular signaling initiated by HER2, however, the data are very controversial. A major issue is the different cellular background of various breast cancer cells lines used in these studies. Each breast cancer cell line has a unique expression profile of various HER receptors, which could significantly affect the effects of trastuzumab.

METHODS

To overcome this problem, in this research we adopted a cell model that allow us to specifically examine the effects of trastuzumab on a single HER receptor without the influence of other HER receptors. Three CHO cell lines stably expressing only human EGFR (CHO-EGFR), HER2 (CHO-K6), or HER3 (CHO-HER3) were used. Various methods including cytotoxicity assay, immunoblotting, indirect immunofluorescence, cross linking, and antibody-dependent cellular cytotoxicity (ADCC) were employed in this research.

RESULTS

We showed that trastuzumab did not bind EGFR and HER3, and thus did not affect the homodimerization and phosphorylation of EGFR and HER3. However, overexpression of HER2 in CHO cells, in the absence of other HER receptors, resulted in the homodimerization of HER2 and the phosphorylation of HER2 at all major pY residues. Trastuzumab bound to HER2 specifically and with high affinity. Trastuzumab inhibited neither the homodimerization of HER2, nor the phosphorylation of HER2 at most phosphotyrosine residues. Moreover, trastuzumab did not inhibit the phosphorylation of ERK and AKT in CHO-K6 cells, and did not inhibit the proliferation of CHO-K6 cells. However, trastuzumab induced strong ADCC in CHO-K6 cells.

CONCLUSION

We concluded that, in the absence of other HER receptors, trastuzumab exerts its antitumor activity through the induction of ADCC, rather than the inhibition of HER2-homodimerization and phosphorylation.

Outcomes of re-treatment with first-line trastuzumab plus a taxane in HER2 positive metastatic breast cancer patients after (neo)adjuvant trastuzumab: A prospective multicenter study

Trastuzumab is the backbone of HER2-positive early breast cancer (eBC) and metastatic breast cancer (mBC) treatment, but limited data exist as to re-treatment in relapsed patients. In this prospective, single arm, multicenter trial, we assessed efficacy and safety of trastuzumab and taxane combination in Chinese patients with HER2-positive mBC relapsed after prior (neo)adjuvant trastuzumab. Patients with previous (neo)adjuvant trastuzumab treatment for≥9 weeks and a relapse-free interval ≥6 months were assigned to trastuzumab treatment with paclitaxel or docetaxel. The primary endpoint was progression free survival (PFS). Secondary endpoints included overall response rate (ORR), clinical benefit rate (CBR), duration of response (DOR), time to progression (TTP), overall survival (OS) and safety profile. Thirty-two patients were enrolled and treated for a median duration of 33.5 weeks. The median PFS was 9.9 months (95% CI, 6.28 - 13.63 months). The ORR was 81.3% (95% CI, 63.6% - 92.8%) and CBR (CR+PR+SD≥6months) was 81.3% (95% CI, 63.6% - 92.8%). The median DOR was 9.8 months (95% CI, 5.82 - 11.60 months) and median TTP was 9.9 months (95% CI, 6.28-13.63 months). OS median follow-up time was 20.1 months and 25% OS time was 25.5 months. The safety profile was acceptable with common adverse events including leukopenia (59.4%), neutropenia (56.3%), hypoaesthesia (34.4%) and granulocytopenia (31.3%). In conclusion, re-treatment with trastuzumab plus a taxane as first-line therapy is an effective regimen for patients with HER2-positive mBC relapsed after (neo)adjuvant trastuzumab. The safety profile was good and the adverse reactions were tolerable and manageable.

Novel multi‑kinase inhibitor, T03 inhibits Taxol‑resistant breast cancer

Activation of kinase-associated signaling pathways is one of the leading causes of various malignant phenotypes in breast tumors. Strategies of drug discovery and development have investigated approaches to target the inhibition of protein kinase signaling. In the current study, the anti‑tumor activities of a novel multi‑kinase inhibitor, T03 were evaluated in breast cancer. T03 inhibited Taxol‑resistant breast cancer cell proliferation and induced cell cycle arrest and apoptosis in vitro and in vivo. The current results demonstrated that T03 downregulated c‑Raf, platelet‑derived growth factor receptor‑β and other kinases, thus inhibited Raf/mitogen‑activated protein kinase kinase/extracellular signal‑regulated kinase and Akt/mechanistic target of rapamycin survival pathways in MCF‑7 and MCF‑7/Taxol xenograft tumors. At a dose of 100 mg/kg, T03 inhibited tumor growth by 62.90 and 59.98% in tumor weight in MX‑1 and MX‑1/T xenograft models, respectively and by 62.60 and 60.22% in MCF‑7 and MCF‑7/T tumors, respectively. These data indicate that the novel multi‑kinase inhibitor, T03, may present as a potential compound to develop novel treatments against breast cancer and Taxol‑resistant breast tumors.

Differential expression of VEGFR2 protein in HER2 positive primary human breast cancer: potential relevance to anti-angiogenic therapies

Background

Clinically relevant predictive biomarkers to tailor anti-angiogenic therapies to breast cancer (BRC) patient subpopulations are an unmet need.

Methods

We analyzed tumor vascular density and VEGFR2 protein expression in various subsets of primary human BRCs (186 females; Mean age: 59 years; range 33–88 years), using a tissue microarray. Discrete VEGFR2+ and CD34+ tumor vessels were manually scored in invasive ductal, lobular, mixed ductal-lobular and colloid (N = 139, 22, 18, 7) BRC cores.

Results

The observed CD34+ and VEGFR2+ tumor vascular counts in individual cases were heterogeneous. Mean CD34+ and VEGFR2+ tumor vessel counts were 11 and 3.4 per tumor TMA core respectively. Eighty-nine of 186 (48%) cases had >10 CD34+ tumor vessels, while 97/186 (52%) had fewer CD34+ vessels in each TMA core. Of 169 analyzable cores in the VEGFR2 stained TMA, 90 (53%) showed 1–5 VEGFR2+ tumor vessels/TMA core, while 42/169 (25%) cores had no detectable VEGFR2+ tumor vessels. Thirteen of 169 (8%) cases also showed tumor cell (cytoplasmic/membrane) expression of VEGFR2. Triple-negative breast cancers (TNBCs) appeared to be less vascular (Mean VD = 9.8, range 0–34) than other breast cancer subtypes. Overall, VEGFR2+ tumor vessel counts were significantly higher in HER2+ as compared to HR+ (p = 0.04) and TNBC (p = 0.02) tissues. Compared to HER2− cases, HER2+ breast cancers had higher VEGFR2+ tumor vessel counts (p = 0.007).

Conclusion

Characterization of pathologic angiogenesis in HER2+ breast cancer provides scientific rationale for future investigation of clinical activity of agents targeting the VEGF/VEGFR2 axis in this clinically aggressive breast cancer subtype.

Metronomic chemotherapy for advanced breast cancer patients

Metronomic chemotherapy refers to the minimum biologically effective dose of a chemotherapy agent given as a continuous dosing regimen with no prolonged drug-free breaks that leads to antitumor activity. This schedule seems to have not only a direct cytotoxicity on cancer cells but also an effect on the tumor microenvironment by inhibiting tumor angiogenesis and modulating immune response. Metronomic chemotherapy was widely investigated in patients with breast cancer. The results of these studies showed that this strategy is not only effective but has a low toxicity profile too, proposing as a promising strategy for breast cancer patients. In this review we summarize the results of Phase II and III studies evaluating metronomic therapy in metastatic breast cancer.

Suppression of tumor angiogenesis by metformin treatment via a mechanism linked to targeting of HER2/HIF-1α/VEGF secretion axis

Anti-angiogenesis is currently considered as one of the major antitumor strategies for its protective effects against tumor emergency and later progression. The anti-diabetic drug metformin has been demonstrated to significantly inhibit tumor angiogenesis based on recent studies. However, the mechanism underlying this anti-angiogenic effect still remains an enigma. In this study, we investigated metformin-induced inhibitory effect on tumor angiogenesis in vitro and in vivo. Metformin pretreatment significantly suppressed tumor paracrine signaling-induced angiogenic promotion even in the presence of heregulin (HRG)-β1 (a co-activator of HER2) pretreatment of HER2+ tumor cells. Similar to that of AG825, a specific inhibitor of HER2 phosphorylation, metformin treatment decreased both total and phosphorylation (Tyr 1221/1222) levels of HER2 protein and significantly reduced microvessel density and the amount of Fitc-conjugated Dextran leaking outside the vessel. Furthermore, our results of VEGF-neutralizing and -rescuing tests showed that metformin markedly abrogated HER2 signaling-induced tumor angiogenesis by inhibiting VEGF secretion. Inhibition of HIF-1α signaling by using RNAi or YC-1, a specific inhibitor of HIF-1α synthesis, both completely diminished mRNA level of VEGF and greatly inhibited endothelial cell proliferation promoted by HER2+ tumor cell-conditioned medium in both the absence and presence of HRG-β1 pretreatment. Importantly, metformin treatment decreased the number of HIF-1α nucleus positive cells in 4T1 tumors, accompanied by decreased microvessel density. Our data thus provides novel insight into the mechanism underlying the metformin-induced inhibition of tumor angiogenesis and indicates possibilities of HIF-1α-VEGF signaling axis in mediating HER2-induced tumor angiogenesis.

Interaction of a standardized mistletoe (Viscum album) preparation with antitumor effects of Trastuzumab in vitro

Background

Besides conventional anticancer therapy many breast cancer patients use complementary and alternative medicine (CAM) like the medicinal herb mistletoe (Viscum album L.). To gain more knowledge about possible herb-drug interactions between CAM and conventional anticancer medications, in the present in vitro study we investigated the effect of a standardized mistletoe preparation on the action of Trastuzumab, a drug used for the treatment of Her-2 positive breast cancer.

Methods

The Her-2 positive human breast carcinoma cell line SK-BR-3 was treated with Trastuzumab. Different doses of the drug were combined with Viscum album extract (VAE) in clinically relevant doses. Proliferation, apoptosis, cell cycle and the secretion of vascular endothelial growth factor (VEGF) were analyzed.

Results

No inhibition of antitumor efficacy of Trastuzumab by VAE was detected. VAE and Trastuzumab, either alone or in combination, inhibited proliferation of SK-BR-3 cells in vitro. At higher concentrations VAE induced apoptosis, which was not observed for Trastuzumab. Cells treated with Trastuzumab underwent a G0/G1 cell cycle arrest and cells treated with VAE a G2/M arrest. After application of the two drugs in combination both G0/G1 and G2/M arrest was observed. VEGF secretion of SK-BR-3 cells was significantly inhibited by sole treatment with Trastuzumab or VAE. Combined treatment of Trastuzumab and VAE at clinically relevant doses showed additive inhibitory effects on VEGF secretion.

Conclusions

VAE did not interfere with cytostatic effects of Trastuzumab on SK-BR-3 cells in vitro. Our in vitro results suggest that no risk of safety by herb drug interactions has to be expected from the exposition of cancer cells to Trastuzumab and VAE simultaneously. In contrast, VAE and Trastuzumab seem to exhibit complementary anti-cancer effects in vitro.

Thymoquinone inhibits inflammation, neoangiogenesis and vascular remodeling in asthma mice

Asthma is a chronic obstructive disease which is characterized by recurring airway inflammation, reversible airway obstruction, airway hyper responsiveness and vascular remodeling. Thymoquinone (TQ), an active ingredient isolated from Nigella sativa, was reported to exhibit anti-inflammation and anti-proliferation of in various cancer cells as well as epithelial cells. The aim of this study was to evaluate the effect of TQ on the inflammation, neoangiogenesis and vascular remodeling induced by Ovalbumin (OVA) in asthma mice in vivo and the anti-angiogenesis effects of TQ in VEGF-induced human umbilical vein endothelial cells (HUVECs) in vitro. Our results revealed that TQ inhibited the production of inflammatory factors interleukin-4/-5 (IL-4/-5) by enzyme-linked immunesorbent assay (ELISA). Immunohistochemistry analysis showed that the increase of platelet endothelial cell adhesion molecule-1, which is also known as CD31 and α-smooth muscle actinalpha (α-SMA) expression in asthma mice challenged by OVA was suppressed by TQ. Moreover, TQ suppressed the activation of VEGFR2-PI3K-Akt pathway and up-regulated the expression of Slit glycoprotein-2 (Slit-2) both in vivo and in vitro with the inhibition of tube information in HUVEC cells. Meanwhile immunofluorescence analysis showed that Slit-2 and Roundabout-4 (Robo-4) were co-expressing after TQ treatment in OVA-challenged asthma mice. Our study demonstrates that TQ attenuated the inflammatory reaction by antagonizing IL-4/-5 while the anti-neoangiogenesis effect of TQ is mediated by inhibition of vascular endothelial growth factor (VEGF) expression through VEGFR2/PI3K/Akt signaling pathway, which supports a potential role for TQ in ameliorating asthma.

Effects of lapatinib and trastuzumab on vascular endothelial growth factor in experimental corneal neovascularization

BACKGROUND

The aim of this study was to compare the effects of lapatinib and trastuzumab on vascular endothelial growth factor on experimental corneal neovascularization.

METHODS

A total of 35 Wistar albino rats were randomly divided into five groups, each containing seven animals. Corneas of rats in the control group were not cauterized and did not receive any treatment. A silver nitrate pencil was applied on the right corneas of rats in the non-control groups to induce corneal neovascularization. Rats in the sham, lapatinib, trastuzumab and lapatinib +  trastuzumab groups were administered systemic saline, 50 mg/kg lapatinib once a day orally by gavage, 4 mg/kg trastuzumab once a day intraperitoneally, or 50 mg/kg lapatinib once a day orally by gavage together with 4 mg/kg trastuzumab once a day intraperitoneally, respectively, for 7 days. Rats were sacrificed on the eighth day, and corneas were excised using a 4-mm punch trephine. Vascular endothelial growth factor immunostaining in the corneal epithelial and stromal layers was evaluated. Staining intensities were determined semi-quantitatively, and corneal vascular endothelial growth factor levels were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean immunostaining intensities of epithelial and stromal vascular endothelial growth factor in the control group were significantly lesser than those in the sham group (P < 0.05). The mean immunostaining intensities of epithelial and stromal vascular endothelial growth factor and vascular endothelial growth factor enzyme-linked immunosorbent assay levels of corneas in all treatment groups (lapatinib, trastuzumab and lapatinib + trastuzumab groups) were lesser than those in the sham group (P < 0.05); however, it was similar to those in the control group (P > 0.05).

CONCLUSIONS

It is suggested that systemically administered lapatinib is more effective than systemically administered trastuzumab in preventing corneal neovascularization.

Is administration of trastuzumab an independent risk factor for developing osteonecrosis of the jaw among metastatic breast cancer patients under zoledronic acid treatment?

One of the most important adverse effects of zoledronic acid (ZA) is osteonecrosis of the jaw (ONJ). In previous literature, several risk factors have been identified in the development of ONJ. In this study, we aimed to determine the role of trastuzumab, an antiangiogenic agent, as an independent risk factor for the development of this serious side effect.Our study included 97 patients (mean age: 54 ± 10 years) with breast cancer, recorded in the archives of the Istanbul Florence Nightingale Breast Study Group, who received ZA therapy due to bone metastases between March 2006 and December 2013. We recorded the patients' ages, weights, duration of treatment with ZA, number of ZA infusions, dental procedures, anticancer treatments (chemotherapy, aromatase inhibitor, trastuzumab), the presence of diabetes mellitus or renal dysfunction, and smoking habits.Thirteen patients (13.40%) had developed ONJ. Among the patients with ONJ, the mean time of exposure to ZA was 41 months (range: 13-82) and the mean number of ZA infusions was 38 (range: 15-56). The duration of treatment with ZA and the use of trastuzumab were observed to be 2 factors that influenced the development of ONJ (P = 0.049 and P = 0.028, respectively).The development of ONJ under ZA treatment may be associated solely with the duration of ZA treatment and the concurrent administration of trastuzumab. These findings show that patients who are administered trastuzumab for metastatic breast cancer while undergoing ZA treatment are prone to developing ONJ. Therefore, we recommend intense clinical observation to avoid this particular condition in patients receiving ZA and trastuzumab.

Progressive loss of anti-HER2 CD4+ T-helper type 1 response in breast tumorigenesis and the potential for immune restoration

Genomic profiling has identified several molecular oncodrivers in breast tumorigenesis. A thorough understanding of endogenous immune responses to these oncodrivers may provide insights into immune interventions for breast cancer (BC). We investigated systemic anti-HER2/neu CD4⁺ T-helper type-1 (Th1) responses in HER2-driven breast tumorigenesis. A highly significant stepwise Th1 response loss extending from healthy donors (HD), through HER2^pos-DCIS, and ultimately to early stage HER2^pos-invasive BC patients was detected by IFNγ ELISPOT. The anti-HER2 Th1 deficit was not attributable to host-level T-cell anergy, loss of immune competence, or increase in immunosuppressive phenotypes (T_reg/MDSCs), but rather associated with a functional shift in IFNγ:IL-10-producing phenotypes. HER2^high, but not HER2^low, BC cells expressing IFNγ/TNF-α receptors were susceptible to Th1 cytokine-mediated apoptosis in vitro, which could be significantly rescued by neutralizing IFNγ and TNF-α, suggesting that abrogation of HER2-specific Th1 may reflect a mechanism of immune evasion in HER2-driven tumorigenesis. While largely unaffected by cytotoxic or HER2-targeted (trastuzumab) therapies, depressed Th1 responses in HER2^pos-BC patients were significantly restored following HER2-pulsed dendritic cell (DC) vaccinations, suggesting that this Th1 defect is not "fixed" and can be corrected by immunologic interventions. Importantly, preserved anti-HER2 Th1 responses were associated with pathologic complete response to neoadjuvant trastuzumab/chemotherapy, while depressed responses were observed in patients incurring locoregional/systemic recurrence following trastuzumab/chemotherapy. Monitoring anti-HER2 Th1 reactivity following HER2-directed therapies may identify vulnerable subgroups at risk of clinicopathologic failure. In such patients, combinations of existing HER2-targeted therapies with strategies to boost anti-HER2 CD4⁺ Th1 immunity may decrease the risk of recurrence and thus warrant further investigation.

Morphological and molecular characteristics of HER2 amplified urothelial bladder cancer

Several (pre-) clinical trials are currently investigating the benefit of HER2-targeted therapy in urothelial bladder cancer (UBC). Patients with HER2 amplified UBC could potentially profit from these therapies. However, little is known about histomorphology, HER2 protein expression patterns and occurrence of alterations in the HER2 gene in their tumors. Among 150 metastasizing primary UBC, 13 HER2 amplified tumors were identified. Their histopathological features were compared with 13 matched, non-amplified UBC. HER2 protein expression was determined by immunohistochemistry. The 26 tumors were screened for mutations in exons 19 and 20 of the HER2 gene. UBC with HER2 amplification presented with a broad variety of histological variants (median 2 vs. 1), frequently featured micropapillary tumor components (77 % vs. 8 %) and demonstrated a high amount of tumor associated inflammation. Immunohistochemically, 10 of 13 (77 %) HER2 amplified tumors were strongly HER2 protein positive. Three tumors (23 %) were scored as HER2 negative. One of the HER2 amplified tumors harbored a D769N mutation in exon 19 of the HER2 gene; all other tested tumors were wild type. In conclusion, HER2 amplified UBC feature specific morphological characteristics. They frequently express the HER2 protein diffusely and are, therefore, promising candidates for HER2 targeted therapies. The detection of mutations at the HER2 locus might add new aspects to molecular testing of UBC.

Recent advances reveal IL-8 signaling as a potential key to targeting breast cancer stem cells

Breast cancer stem-like cells (CSCs) are an important therapeutic target as they are purported to be responsible for tumor initiation, maintenance, metastases, and disease recurrence. Interleukin-8 (IL-8) is upregulated in breast cancer compared with normal breast tissue and is associated with poor prognosis. IL-8 is reported to promote breast cancer progression by increasing cell invasion, angiogenesis, and metastases and is upregulated in HER2-positive cancers. Recently, we and others have established that IL-8 via its cognate receptors, CXCR1 and CXCR2, is also involved in regulating breast CSC activity. Our work demonstrates that in metastatic breast CSCs, CXCR1/2 signals via transactivation of HER2. Given the importance of HER2 in breast cancer and in regulating CSC activity, a pathway driving the activation of these receptors would have important biological and clinical consequences, especially in tumors that express high levels of IL-8 and other CXCR1/2-activating ligands. Here, we review the IL-8 signaling pathway and the role of HER2 in maintaining an IL-8 inflammatory loop and discuss the potential of combining CXCR1/2 inhibitors with other treatments such as HER2-targeted therapy as a novel approach to eliminate CSCs and improve patient survival.

Impact of trastuzumab on wound healing in experimental glaucoma surgery

BACKGROUND

To investigate the effects of subconjunctivally administered trastuzumab on wound healing in experimental glaucoma filtration surgery.

DESIGN

Comparative, experimental study.

SAMPLES

Twenty eight eyes.

METHODS

Twenty-eight male New Zealand white rabbits were randomly assigned to four groups, each including seven rabbits: The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the mitomycin-C group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL mitomycin-C was applied intraoperatively to the scleral surgical site for 3 min. The rabbits in the trastuzumab group underwent trabeculectomy and were injected subconjunctivally once with 1.2 mg/0.1 mL of the drug. On day 14 of the experiment, the operated and control eyes were enucleated and immunohistochemically analyzed.

MAIN OUTCOME MEASURES

Mean values of fibroblast, mononuclear cell and immunostaining intensities of the transforming growth factor-β, fibroblast growth factor-β, and platelet derived growth factor.

RESULTS

The mean cell numbers and immunostaining intensities in the sham group were higher than those of the control group (P < 0.01). The mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were statistically significantly lower than those of the sham group (P < 0.01) while mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were similar (P > 0.05).

CONCLUSION

Subconjunctival trastuzumab injection effectively suppressed subconjunctival scarring after experimental glaucoma filtration surgery.

Influence of boost radiotherapy in patients with ductal carcinoma in situ breast cancer: a multicenter, retrospective study in Korea (KROG 11-04)

To estimate the effect of boost radiotherapy on local recurrence-free survival (LRFS) in patients with ductal carcinoma in situ (DCIS) breast cancer. We included patients from nine institutions who met the following criteria: having Tis, age 18 years or older, having breast conserving surgery (BCS) and radiotherapy within 12 weeks after surgery. From 1995 through 2006, 728 patients were analyzed retrospectively by the Korean Radiation Oncology Group. All patients received whole-breast radiation therapy (WBRT) after BCS. 232 patients (31.9 %) also received boost radiation therapy (RT) (median 10 Gy). After median follow-up of 82 months, 5-year LRFS was 98.4 % and 10-year LRFS was 95.8 % for all patients. There was no statistically significant difference of LRFS between the boost and no-boost groups. Nineteen (2.6 %) patients had ipsilateral breast recurrences, including 12 of invasive recurrence and 7 DCIS. The presence of the HER2 receptor was associated with more invasive recurrences. Nine (1.2 %) patients developed contralateral breast cancer, including six invasive breast cancer and three DCIS. In the multivariate analysis, only the margin status was a significant prognostic factor for LRFS. Boost RT was not associated with further improvement of local control in DCIS after BCS and WBRT. HER2 receptor-positive patients may need further treatment with the anti-HER2 agents.

Characterization of proapoptotic compounds from the bark of Garcinia oblongifolia

Twenty compounds from Garcinia oblongifolia were screened for proapoptotic activity using FRET-based HeLa-C3 sensor cells. Among them, oblongifolins F and G (1 and 2), 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthone (3), nigrolineaxanthone T (4), and garcicowin B (5) showed significant proapoptotic activity at a concentration of 10 μM. Bioassessments were then performed to evaluate the potential of these compounds for therapeutic application. All five compounds showed significant cytotoxicity and caspase-3-activating ability in cervical cancer HeLa cells, with compounds 1 and 2 having the highest potencies. All five compounds specifically induced caspase-dependent apoptosis, which could be prevented by the pan-caspase inhibitor zVAD-fmk. In particular, 3 induced apoptosis through mitotic arrest. Compounds 1-5 displayed similar IC50 values (3.9-16.5 μM) against the three cancer cell lines HeLa, MDA-MB-435, and HepG2. In addition, compounds 1, 2, and 4 exhibited similar and potent IC50 values (2.4-5.1 μM) against several breast and colon cancer cell lines, including those overexpressing either HER2 or P-glycoprotein. HER2 and P-glycoprotein are known factors that confer resistance to anticancer drugs in cancer cells. This is the first study on the cytotoxicity, caspase-3-activing ability, and specificity of proapoptotic compounds isolated from G. oblongifolia in HeLa cells. The potential application of these compounds against HER2- or P-glycoprotein-overexpressing cancer cells was investigated.

Engagement of immune effector cells by trastuzumab induces HER2/ERBB2 downregulation in cancer cells through STAT1 activation

Introduction

Trastuzumab has been widely used for the treatment of human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer for more than a decade. However, reports on the involvement of HER2 downregulation in trastuzumab’s mechanism of action are inconsistent. The aim of this study is to investigate if the dependence of trastuzumab-mediated cancer cell HER2 downregulation on immune effector cells represents a novel mechanism of action for trastuzumab.

Methods

HER2 expression was evaluated by Western blotting, flow cytometry, and real-time polymerase chain reaction (PCR) in cell lysates from co-cultures of multiple cancer cell lines with peripheral blood mononuclear cells (PBMCs) in the presence or absence of trastuzumab. The engagement of immune cells by trastuzumab through Fc gamma receptors (FcγRs) was tested using three trastuzumab variants with compromised or no Fc (fragment crystallizable) functions and FcγRs blocking experiments. The engagement of immune cells by trastuzumab in HER2 downregulation was also evaluated in in vivo mouse xenograft tumor models.

Results

HER2 downregulation of cancer cells by trastuzumab occurred only when trastuzumab was actively engaged with immune cells and cancer cells, as demonstrated consistently in co-cultures of cancer cell lines with PBMCs and in vivo mouse xenograft tumor models. We further demonstrated that HER2 downregulation in cancer cells by immune-cell-engaged trastuzumab was at the transcriptional level, not through the HER2 degradation pathway. Activation of signal transducer and activator of transcription 1 (STAT1) in cancer cells by the increased interferon gamma (IFN-γ) production in immune cells played an important role in downregulating HER2 in cancer cells upon engagement of immune cells by trastuzumab. Furthermore, HER2 downregulation in cancer cells induced by trastuzumab engagement of immune cells was correlated with the antibody’s antitumor efficacy in vivo.

Conclusions

This study reveals that engagement of immune effector cells by trastuzumab induces HER2 downregulation in HER2-expressing cancer cells, which represents a new function of immune cells in trastuzumab-mediated antitumor efficacy and serves as a novel mechanism of action for trastuzumab. Our results imply that HER2 downregulation in cancer cells treated by trastuzumab may predict active engagement of immune effector cells in tumor microenvironment.

ATP directed agent, 8-chloro-adenosine, induces AMP activated protein kinase activity, leading to autophagic cell death in breast cancer cells

Background

8-chloro-adenosine (8-Cl-Ado) is a unique ribonucleoside analog which is currently in a phase I clinical trial for hematological malignancies. Previously, we demonstrated in breast cancer cells that a 3-day treatment with 10 μM 8-Cl-Ado causes a 90% loss of clonogenic survival. In contrast, there was only a modest induction of apoptosis under these conditions, suggesting an alternative mechanism for the tumoricidal activity of 8-Cl-Ado.

Methods

Cellular metabolism, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway signaling, as well as autophagy induction was evaluated in breast cancer cell lines treated with 8-Cl-Ado. The effects of knocking down essential autophagy factors with small interfering RNA on 8-Cl-Ado-inhibited cell survival was assessed in breast cancer cells by examining apoptosis induction and clonogenic survival. In vivo efficacy of 8-Cl-Ado was measured in two breast cancer orthotopic model systems.

Results

We demonstrate that in breast cancer cell lines, the metabolism of 8-Cl-Ado results in depletion of endogenous ATP that subsequently induces the phosphorylation and activation of the energy sensor, AMPK. This was associated with an attenuation of mTOR signaling and an induction of the phosphorylation of the autophagy factor, Unc51-like kinase 1 on Ser555. 8-Cl-Ado-mediated induction of autophagy was evident by increased aggregates of microtubule-associated protein 1 light chain 3B (LC3B) which was associated with its conversion to its lipidated form, LC3B-II, p62 degradative flux, and increased formation of acidic vesicular organelles. Additionally, transfection of MCF-7 cells with siRNA to ATG7 or beclin 1 provided partial protection of the cells to 8-Cl-Ado cytotoxicity as measured by clonogenicity. In vivo, 8-Cl-Ado inhibited growth of both MCF-7 and BT-474 xenograft tumors. Moreover, in 9 of 22 BT-474 tumors treated with 100 mg/kg/day 3 times a week, there was an absence of macroscopically detectable tumor after 3 weeks of treatment.

Conclusions

Our data demonstrates that 8-Cl-Ado treatment activates the AMPK pathway leading to autophagy induction of in breast cancer cells, eliciting, in part, its tumoricidal effects. Additionally, 8-Cl-Ado effectively inhibited in vivo tumor growth in mice. Based on this biological activity, we are planning to test 8-Cl-Ado in the clinic for patients with breast cancer.

Combined blockade of HER2 and VEGF exerts greater growth inhibition of HER2-overexpressing gastric cancer xenografts than individual blockade

Gastric cancer overexpressing the human epidermal growth factor 2 (HER2) protein has a poor outcome, although a combination of chemotherapy and the anti-HER2 antibody trastuzumab has been approved for the treatment of advanced gastric cancer. Vascular endothelial growth factor (VEGF) expression in gastric cancer is correlated with recurrence and poor prognosis; however, the anti-VEGF antibody bevacizumab has shown limited efficacy against gastric cancer in clinical trials. In this study, we evaluated the antitumor effects of trastuzumab; VEGF-Trap binding to VEGF-A, VEGF-B and placental growth factor (PlGF); and a combination of trastuzumab and VEGF-Trap in a gastric cancer xenograft model. Although trastuzumab and VEGF-Trap each moderately inhibited tumor growth, the combination of these agents exerted greater inhibition compared with either agent alone. Immunohistochemical analyses indicated that the reduction in tumor growth was associated with decreased proliferation and increased apoptosis of tumor cells and decreased tumor vascular density. The combined treatment resulted in fewer proliferating tumor cells, more apoptotic cells and reduced tumor vascular density compared with treatment with trastuzumab or VEGF-Trap alone, indicating that trastuzumab and VEGF-Trap had additive inhibitory effects on the tumor growth and angiogenesis of the gastric cancer xenografts. These data suggest that trastuzumab in combination with VEGF-Trap may represent an effective approach to treating HER2-overexpressing gastric cancer.

Interleukin-8 in breast cancer progression

Interleukin-8 (IL-8) is a chemokine that has an autocrine and/or paracrine tumor-promoting role and significant potential as a prognostic and/or predictive cancer biomarker. In breast cancer, which is mostly determined by expression of estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2), IL-8 could play a specific role. IL-8 is highly expressed in ER- breast cancers, but it increases invasiveness and metastatic potential of both ER- and ER+ breast cancer cells. It is also highly expressed in HER2+ breast cancers. Because of the complex crosstalk between these receptors and IL-8, its role is mainly determined by delicate balance in their signaling pathways. Therefore, the main point of this review was to analyze the possible influence of IL-8 in breast cancer progression related to its interaction with ER and HER2 and the consequent therapeutic implications of these relations.