Treatment Of HER2-overexpressing Breast Cancer Research Articles

Photodynamic Therapy of Cancer: Quality and Prospective of Therapy based on Photosensitizer

Abstract: To kill cancer cells, photodynamic therapy (PDT) utilizes a light-sensitive medication and light. Light-sensitive drugs are absorbed by cancerous cells. The cells are then illuminated with a specific light or laser by a specialist and oxygen that destroys cancer cells is released. The present study aims to discuss the roles, advancements, and limitations of photodynamic therapy in cancer treatment. Photosensitizers and photosensitizing agents are used in photodynamic treatment to destroy cancer cells. Lasers or other light sources, such as LEDs, may provide illumination. There are reports of a novel nanoplatform for the treatment of HER2-overexpressed breast cancer, as well as other primary and metastatic cancers, using fluorescent electron microscopy PDT/photothermal therapy (PTT) dualtherapy. PDT has a significant benefit over conventional cancer therapies because it may cause fewer adverse effects. PDT-induced immunostimulatory cell death and the production of a robust local inflammatory response might lead to effective local anticancer therapy. PDT has a lower long-term morbidity and recovery time than surgery, chemotherapy, or radiation.

Therapeutic Potential of MF-TTZ-MMAE, a Site-Specifically Conjugated Antibody-Drug Conjugate, for the Treatment of HER2-Overexpressing Breast Cancer.

With three clinically approved antibody-drug conjugates targeting HER2, this target is clearly identified to be of interest in oncology. Moreover, the advent of new bioconjugation technologies producing site-specific homogenous conjugates led to the opportunity of developing new medicines linking antibodies and payloads. Here, a new relevant HER2-targeting ADC was obtained by the conjugation of monomethyl auristatin E onto trastuzumab using McSAF Inside bioconjugation technology. The antibody-drug conjugate formed presented an average drug-to-antibody ratio of 4 with a high homogeneity and an excellent stability especially when incubated with human serum albumin or in human plasma. Moreover, it demonstrated a strong efficacy in an HER2 xenograft tumor model in mice, superior to the clinically approved antibody-drug conjugate ado-trastuzumab emtansine, with a complete tumor regression observed both macroscopically and microscopically demonstrating its therapeutic potential.

Discovery and Pharmacological Evaluation of STEAP4 as a Novel Target for HER2 Overexpressing Breast Cancer.

Breast cancer (BC) is a highly heterogeneous disease encompassing multiple subtypes with different molecular and histopathological features, disease prognosis, and therapeutic responses. Among these, the Triple Negative BC form (TNBC) is an aggressive subtype with poor prognosis and therapeutic outcome. With respect to HER2 overexpressing BC, although advanced targeted therapies have improved the survival of patients, disease relapse and metastasis remains a challenge for therapeutic efficacy. In this study the aim was to identify key membrane-associated proteins which are overexpressed in these aggressive BC subtypes and can serve as potential biomarkers or drug targets. We leveraged on the development of a membrane enrichment protocol in combination with the global profiling GeLC-MS/MS technique, and compared the proteomic profiles of a HER2 overexpressing (HCC-1954) and a TNBC (MDA-MB-231) cell line with that of a benign control breast cell line (MCF-10A). An average of 2300 proteins were identified from each cell line, of which approximately 600 were membrane-associated proteins. Our global proteomic methodology in tandem with invigoration by Western blot and Immunofluorescence analysis, readily detected several previously-established BC receptors like HER2 and EPHA2, but importantly STEAP4 and CD97 emerged as novel potential candidate markers. This is the first time that the mitochondrial iron reductase STEAP4 protein up-regulation is linked to BC (HER2+ subtype), while for CD97, its role in BC has been previously described, but never before by a global proteomic technology in TNBC. STEAP4 was selected for further detailed evaluation by the employment of Immunohistochemical analysis of BC xenografts and clinical tissue microarray studies. Results showed that STEAP4 expression was evident only in malignant breast tissues whereas all the benign breast cases had no detectable levels. A functional role of STEAP4 intervention was established in HER2 overexpressing BC by pharmacological studies, where blockage of the STEAP4 pathway with an iron chelator (Deferiprone) in combination with the HER2 inhibitor Lapatinib led to a significant reduction in cell growth in vitro. Furthermore, siRNA mediated knockdown of STEAP4 also suppressed cell proliferation and enhanced the inhibition of Lapatinib in HER2 overexpressing BC, confirming its potential oncogenic role in BC. In conclusion, STEAP4 may represent a novel BC related biomarker and a potential pharmacological target for the treatment of HER2 overexpressing BC.

Arctigenin-mediated cell death of SK-BR-3 cells is caused by HER2 inhibition and autophagy-linked apoptosis.

Human epidermal growth factor receptor 2 (HER2) is well-known as the therapeutic marker in breast cancer. Therefore, we evaluated anti-cancer activity of arctigenin (ATG) on in SK-BR-3 HER2-overexpressing human breast cancer cells. Cell viability and cytotoxicity were analyzed with MTT and colony-forming assay and cell cycle analysis was performed by flow cytometry. The expression and/or phosphorylation of proteins in whole cell lysate and mitochondrial fraction were analyzed by Western blotting. Cellular levels of LC3 and sequestosome 1 (SQSTM1/P62) were observed by immunofluorescence analysis. The result showed that ATG decreased cell viability of SK-BR-3 cells in a concentration-dependent manner. Moreover, ATG increased the sub G1 population linked to the suppression of HER2/EGFR1 signaling pathway. Furthermore, ATG increased the phosphorylation of H2AX and down-regulated RAD51 and survivin expressions, indicating that ATG induced DNA damage and inhibited the DNA repair system. We also found that cleavages of caspase-7 and PARP by releasing mitochondrial cytochrome c into the cytoplasm were induced by ATG treatment for 72h through the reduction of Bcl-2 and Bcl-xL levels in mitochondria. In contrast, the levels of LC-3 and SQSTM1/P62 were increased by ATG for 24h through the Akt/mTOR and AMPK signaling pathway. Taken together, this study indicates that autophagy-linked apoptosis is responsible for the anti-cancer activity of ATG in SK-BR-3 cells, and suggests that ATG is considered a potential therapeutic for the treatment of HER2-overexpressing breast cancer.

Acquired resistance to trastuzumab/pertuzumab or to T-DM1 in vivo can be overcome by HER2 kinase inhibition with TAS0728.

HER2‐targeting antibodies (trastuzumab, pertuzumab) and a HER2‐directed antibody‐drug conjugate (trastuzumab emtansine: T‐DM1) are used for the treatment of HER2‐overexpressing breast cancer. However, these treatments eventually become ineffective due to acquired resistance and there is an urgent need for alternative therapies. TAS0728 is a small‐molecule, irreversible selective HER2 kinase inhibitor. In the present study, we established new in vivo models of cancer resistance by continuous exposure to a combination of trastuzumab and pertuzumab or to T‐DM1 for evaluating the effect of TAS0728 on HER2 antibody‐resistant populations. Treatment with trastuzumab and pertuzumab or with T‐DM1 initially induced tumor regression in NCI‐N87 xenografts. However, tumor regrowth during treatment indicated loss of drug effectiveness. In tumors with acquired resistance to trastuzumab and pertuzumab or to T‐DM1, HER2‐HER3 phosphorylation was retained. Switching to TAS0728 resulted in a significant anti‐tumor effect associated with HER2‐HER3 signal inhibition. No alternative receptor tyrosine kinase activation was observed in these resistant tumors. Furthermore, in a patient‐derived xenograft model derived from breast cancer refractory to both trastuzumab/pertuzumab and T‐DM1, TAS0728 exerted a potent anti‐tumor effect. These results suggest that tumors with acquired resistance to trastuzumab and pertuzumab and to T‐DM1 are still dependent on oncogenic HER2‐HER3 signaling and are vulnerable to HER2 signal inhibition by TAS0728. These results provide a rationale for TAS0728 therapy for breast cancers that are refractory to established anti‐HER2 therapies.

MiR-200c suppresses stemness and increases cellular sensitivity to trastuzumab in HER2+ breast cancer.

Resistance to trastuzumab remains a major obstacle in HER2‐overexpressing breast cancer treatment. miR‐200c is important for many functions in cancer stem cells (CSCs), including tumour recurrence, metastasis and resistance. We hypothesized that miR‐200c contributes to trastuzumab resistance and stemness maintenance in HER2‐overexpressing breast cancer. In this study, we used HER2‐positive SKBR3, HER2‐negative MCF‐7, and their CD44+CD24− phenotype mammospheres SKBR3‐S and MCF‐7‐S to verify. Our results demonstrated that miR‐200c was weakly expressed in breast cancer cell lines and cell line stem cells. Overexpression of miR‐200c resulted in a significant reduction in the number of tumour spheres formed and the population of CD44+CD24− phenotype mammospheres in SKBR3‐S. Combining miR‐200c with trastuzumab can significantly reduce proliferation and increase apoptosis of SKBR3 and SKBR3‐S. Overexpression of miR‐200c also eliminated its downstream target genes. These genes were highly expressed and positively related in breast cancer patients. Overexpression of miR‐200c also improved the malignant progression of SKBR3‐S and SKBR3 in vivo. miR‐200c plays an important role in the maintenance of the CSC‐like phenotype and increases drug sensitivity to trastuzumab in HER2+ cells and stem cells.

Development of anti-HER2-targeted doxorubicin-core-shell chitosan nanoparticles for the treatment of human breast cancer.

Purpose: Doxorubicin (DOX) encapsulated O-succinyl chitosan graft Pluronic® F127 (OCP) copolymer nanoparticles conjugated with an anti-HER2 monoclonal antibody were developed as targeted drug delivery vehicles for the treatment of HER2-overexpressing breast cancer.Methods: Five percent and 10% (w/w) of O-succinyl chitosan was grafted onto Pluronic® F127 using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as mediated cross-linking agents. DOX was added to the copolymer solution to form DOX-nanoparticles before conjugation with anti-HER2 on the surface of the nanoparticles.Results: DOX was encapsulated within the NP matrices at an encapsulation efficiency of 73.69 ± 0.53% to 74.65 ± 0.44% (the initial DOX concentration was 5 µg/mL). Anti-HER2 was successfully conjugated onto the surface of the nanoparticles at a moderately high conjugation efficiency of approximately 57.23 ± 0.38% to 61.20 ± 4.42%. In the in vitro DOX dissolution study, the nanoparticle formulations exhibited a biphasic drug release with an initial burst release followed by a sustained release profile at both pH 5.0 and pH 7.4. The drug was rapidly and completely released from the nanoparticles at pH 5.0. In the in vitro cytotoxicity, the anti-HER2 conjugated OCP copolymer nanoparticles showed the lowest IC50, which indicated an increase in the therapeutic efficacy of DOX to treat human breast cancer cells with the HER2 overexpression.Conclusion: Our study shows that anti-HER2 conjugated OCP copolymer nanoparticles have the potential for the development of anticancer drug carriers.

Lipoproteins modulate growth and P-glycoprotein expression in drug-resistant HER2-overexpressed breast cancer cells

BackgroundDrug resistance remains as a challenge in the treatment of HER2-overexpressed breast cancer. Emerging evidence from clinical studies show relation of oxidized low density lipoprotein (LDL) and very low density lipoprotein (VLDL) level with drug resistance. However, the underlying molecular mechanisms for this effect remain unclear. Therefore, the aim of this study was to determine the effects of oxidized-LDL and VLDL in drug-resistant HER2-overexpressed breast cancer cells. MethodsAn in vitro cell model for tamoxifen-resistant HER2 overexpressed UACC732 cells was created using the pulse method. Cells were exposed to oxidized LDL (oxLDL) and very low density lipoprotein (VLDL) separately. Effects on cell morphology was studied using phase contrast microscopic changes. Percentage of cell viability was measured using proliferation assay kit. Development of tamoxifen resistance was determined based on P-gp expression with flow cytometry. Further analysis includedcell death measurement with flow cytometry method. ResultsUACC732 cells exposed to VLDL exhibited fibroblast-like morphology. This was further supported by proliferation assay, where the percentage of cell viability achieved more than 100% with 100 μg/ml of VLDL exposure, indicating cell proliferation. Findings also showed that VLDL caused reduction in expression of Pgp in resistant cells compared to resistant cells alone (p = 0.02). ConclusionResults of this study suggest that VLDL may play a role in growth of drug-resistant HER2-overexpressing cells. Lower expression of P-gp in presence of VLDL need to be investigated further.

DNA-affibody nanoparticle delivery system for cisplatin-based breast cancer chemotherapy.

Cisplatin is the most widely used anticancer drug, but its side effects limit the maximum systemic dose. To circumvent the side effects, a DNA tetrahedron–affibody nanoparticle was prepared by combination of a DNA chain with cisplatin via interstrand crosslinks or adducts. Each nanocarrier can bind ∼68 molecules of cisplatin. This cisplatin nanoparticle exhibited high selectivity and inhibition for breast cancer HER2 overexpressing cells BT474 and lower toxicity in MCF-7 cells with low HER2 expression. The nano-drug inhibited the growth of BT474 cells by 94.57% at 512 nM (containing 33.3 μM cisplatin), which was higher than that of cisplatin (82.9%, 33.3 μM).

Kahweol inhibits proliferation and induces apoptosis by suppressing fatty acid synthase in HER2-overexpressing cancer cells

Kahweol is a coffee-specific diterpene found in the beans of Coffea arabica and has been reported to demonstrate various biological activities, including anti-inflammatory, antioxidant, and apoptotic properties. In the present study, we examined the molecular mechanism of kahweol in human epidermal growth factor receptor-2 (HER2)-overexpressing breast cancer cells. Kahweol preferentially inhibited cell proliferation and induced cell death through the induction of a caspase 3-dependent pathway in HER2-overexpression breast cancer cell lines. Kahweol treatment substantially reduced the levels of HER2 protein, mRNA, and transcriptional activity in SKBR3 cells. Kahweol exerts its potent anticancer efficacy by the upregulation of polyomavirus enhancer activator 3 (PEA3) and downregulation of activator protein 2 (AP-2) to inhibit aberrantly activated HER2 signaling. Fatty acid synthase (FASN) expression and sterol regulatory element-binding protein-1c (SREBP-1c) activity were downregulated by kahweol. In addition, kahweol lowered the levels of phosphorylated Akt and its downstream targets mammalian target of rapamycin (mTOR) and cyclin D1. Furthermore, we found that blocking Akt signaling through kahweol treatment significantly reduced FASN expression and subsequently suppressed cell proliferation in HER2-overexpressing cancer cells. Overall, this study suggests that kahweol could be a useful adjuvant therapeutic agent in the treatment of HER2-overexpressing breast cancer.

Abstract 1837: Overcoming trastuzumab resistance in HER2-overexpressing breast cancer by utilizing PHB2, a tumor suppressor of multiple resistance pathways

Abstract Overexpression of the human epidermal growth factor receptor 2 (HER2) is associated with aggressive tumor behavior and poor prognosis in breast cancer. Although anti-HER2 monoclonal antibody, trastuzumab shows considerable efficacy and extends the overall survival of patients with HER2 overexpressing breast cancer, about half of individuals with HER2-overexpressing breast cancer do not respond to trastuzumab-based therapies due to multiple resistance mechanisms. Therefore, acquired and de novo resistance to trastuzumab remains an important issue in the clinical treatment of HER2-overexpressing breast cancer. Our previous studies demonstrated that Brefeldin A-Inhibited Guanine nucleotide-exchange protein 3 (BIG3), which is exclusively overexpressed in the majority of breast cancers, functions as an A-kinase anchoring protein that binds protein kinase A (PKA) and protein phosphatase 1 (PP1Cα), thereby inactivating prohibitin2 (PHB2) suppressive activity through its dephosphorylation on Ser39. We further developed the stapled dominant-negative peptide (stERAP; stapled ERAP), which is designed to specifically inhibit the BIG3-PHB2 interaction and improve duration of their anti-tumor effects. Here we newly report that stERAP has significant suppressive effects on the HER2 signaling network by activating the tumor suppressive ability of PHB2. Intrinsic PHB2 released from BIG3 by stERAP was rapidly serine- and threonine-phosphorylated via PKCα and/or TTK, which are essential for its tumor suppressive activity, and effectively disrupted the HER2-HER3 interaction associated with acquired resistance to trastuzumab, resulting in significant reduction of proliferation of HER2-overexpressing breast cancer cells (IC50 = 54 nM in SK-BR-3 cells). We also confirm that stERAP inhibited HER2 phosphorylation on Thr488, HER2-HER3 interaction, and NF-κB pathway, which are associated with trastuzumab-resistance, respectively, resulting in significant suppression of growth of trastuzumab-resistant breast cancer cells. More importantly, stERAP treatment led to the enhancement of trastuzumab-sensitivity, resulting in a synergistic growth suppression of HER2-overexpressing and trastuzumab-resistant breast cancer cells, respectively. Our findings strongly suggest that stERAP is a novel promising anti-cancer drug to suppress the growth of trastuzumab-resistant breast cancer in clinical use. Citation Format: Tetsuro Yoshimaru, Yosuke Matsushita, Mitsunori Sasa, Yasuo Miyoshi, Toyomasa Katagiri. Overcoming trastuzumab resistance in HER2-overexpressing breast cancer by utilizing PHB2, a tumor suppressor of multiple resistance pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1837.

Proteolytic single hinge cleavage of pertuzumab impairs its Fc effector function and antitumor activity in vitro and in vivo

BackgroundProteolytic impairment of the Fc effector functions of therapeutic monoclonal antibodies (mAbs) can compromise their antitumor efficacy in the tumor microenvironment and may represent an unappreciated mechanism of host immune evasion. Pertuzumab is a human epidermal growth factor receptor 2 (HER2)-targeting antibody and has been widely used in the clinic in combination with trastuzumab for treatment of HER2-overexpressing breast cancer. Pertuzumab susceptibility to proteolytic hinge cleavage and its impact on the drug’s efficacy has not been previously studied.MethodsPertuzumab was incubated with high and low HER2-expressing cancer cells and proteolytic cleavage in the lower hinge region was detected by western blotting. The single hinge cleaved pertuzumab (scIgG-P) was purified and evaluated for its ability to mediate antibody-dependent cellular cytotoxicity (ADCC) in vitro and anti-tumor efficacy in vivo. To assess the cleavage of trastuzumab (IgG-T) and pertuzumab (IgG-P) when simultaneously bound to the same cancer cell surface, F(ab’)2 fragments of IgG-T or IgG-P were combined with the intact IgG-P and IgG-T, respectively, to detect scIgG generation by western blotting.ResultsPertuzumab hinge cleavage occurred when the mAb was incubated with high HER2-expressing cancer cells. The hinge cleavage of pertuzumab caused a substantial loss of ADCC in vitro and reduced antitumor efficacy in vivo. The reduced ADCC function of scIgG-P was restored by an anti-hinge mAb specific for a cleavage site neoepitope. In addition, we constructed a protease-resistant version of the anti-hinge mAb that restored ADCC and the cell-killing functions of pertuzumab when cancer cells exressed a potent IgG hinge-cleaving protease. We also observed increased hinge cleavage of pertuzumab when combined with trastuzumab.ConclusionThe reduced Fc effector function of single hinge-cleaved pertuzumab can be restored by an anti-hinge mAb. The restoration effect indicated that immune function could be readily augmented when the damaged primary antibodies were bound to cancer cell surfaces. The anti-hinge mAb also restored Fc effector function to the mixture of proteolytically disabled trastuzumab and pertuzumab, suggesting a general therapeutic strategy to restore the immune effector function to protease-inactivated anticancer antibodies in the tumor microenvironment. The findings point to a novel tactic for developing breast cancer immunotherapy.

Effective suppression of tumour cells by oligoclonal HER2-targeted delivery of liposomal doxorubicin

Synergistic effect of combined antibodies targeting distinct epitopes of a particular tumour antigen has encouraged some clinical trial studies and is now considered as an effective platform for cancer therapy. Providing several advantages over conventional antibodies, variable domain of heavy chain of heavy chain antibodies (VHH) is now major tools in diagnostic and therapeutic applications. Active targeting of liposomal drugs is a promising strategy, resulting in enhanced binding and improved cytotoxicity of tumour cells. In the present study, we produced four anti-HER2 recombinant VHHs and purified them via native and refolding method. ELISA and flow cytometry analysis confirmed almost identical function of VHHs in refolded and native states. Using a mixture of four purified VHHs, PEGylated liposomal doxorubicin was targeted against HER2-overexpressing cells. The drug release was analyzed at pH 7.4, 6.4 and 5.5 and dynamic light-scattering detector and TEM micrograph was applied to characterize the produced nanoparticles. The binding efficiency of these nanoparticles to BT474 and SKBR3 as HER2-positive and MCF10A as HER2-negative cell line was examined by flow cytometry. Our results indicated effective encapsulation of about 94% of the total drug in immunoliposomes. Flow cytometry results verified receptor-specific binding of targeted liposomes to SKBR3 and BT474 cell lines and more efficient binding was observed for liposomes conjugated with oligoclonal VHHs mixture compared with monoclonal VHH-targeted liposomes. Oligoclonal nanoparticles also showed more cytotoxicity compared with non-targeted liposomes against HER2-positive tumour cells. Oligoclonal targeting of liposomes was represented as a promising strategy for the treatment of HER2-overexpressing breast cancers.

Targeted Ultrasound-Triggered Phase Transition Nanodroplets for Her2-Overexpressing Breast Cancer Diagnosis and Gene Transfection.

For successful gene therapy, it is imperative to accumulate therapeutic gene in tumor tissues followed by efficiently delivering gene into targeted cells. Ultrasound irradiation, as a noninvasive and cost-effective external stimulus, has been proved to be one of the most potential external-stimulating gene delivery strategies recently in further improving gene transfection. In this study, we developed tumor-targeting ultrasound-triggered phase-transition nanodroplets AHNP-PFP-TNDs comprising a perfluorinated poly(amino acid) C11F17-PAsp (DET) as a core for simultaneously loading perfluoropentane (PFP) and nucleic acids, and a polyanionic polymer PGA-g-PEG-AHNP as the shell for not only modifying the surface of nanodroplets but also introducing an anti-Her2/neu peptide (AHNP) aiming to targeted treatment of Her2-overexpressing breast cancer. The results showed the average diameter of AHNP-PFP-TNDs was below 400 nm, nearly spherical in shape. The modification of PGA-g-PEG-AHNP not only increased the serum stability of the nanodroplets but also improved the affinity between nanodroplets and Her2-overexpressing breast cells. Both intratumor and intravenous injection of AHNP-PFP-TNDs into nude mice bearing HGC-27 xenografts showed that the gene transfection efficiency and the ultrasound contrast effect were significantly enhanced after exposed to the ultrasound irradiation with optimized ultrasound parameters. Therefore, this targeting nanodroplets system could be served as a potential theranostic vector for tumor targeting ultrasound diagnosis and gene therapy.

Induction of G2M Arrest by Flavokawain A, a Kava Chalcone, Increases the Responsiveness of HER2-Overexpressing Breast Cancer Cells to Herceptin.

HER2/neu positive breast tumors predict a high mortality and comprise 25%–30% of breast cancer. We have shown that Flavokawain A (FKA) preferentially reduces the viabilities of HER2-overexpressing breast cancer cell lines (i.e., SKBR3 and MCF7/HER2) versus those with less HER2 expression (i.e., MCF7 and MDA-MB-468). FKA at cytotoxic concentrations to breast cancer cell lines also has a minimal effect on the growth of non-malignant breast epithelial MCF10A cells. FKA induces G2M arrest in cell cycle progression of HER2-overexpressing breast cancer cell lines through inhibition of Cdc2 and Cdc25C phosphorylation and downregulation of expression of Myt1 and Wee1 leading to increased Cdc2 kinase activities. In addition, FKA induces apoptosis in SKBR3 cells by increasing the protein expression of Bim and BAX and decreasing expression of Bcl2, BclX/L, XIAP, and survivin. FKA also downregulates the protein expression of HER-2 and inhibits AKT phosphorylation. Herceptin plus FKA treatment leads to an enhanced growth inhibitory effect on HER-2 overexpressing breast cancer cell lines through downregulation of Myt1, Wee1, Skp2, survivin, and XIAP. Our results suggest FKA as a promising and novel apoptosis inducer and G2 blocking agent that, in combination with Herceptin, enhances for the treatment of HER2-overexpressing breast cancer.

Abstract P4-21-19: Systematic review of clinical trials for monoclonal antibody biosimilars in HER2-positive breast cancer

Abstract Background: A number of proposed trastuzumab (TRAS) biosimilars are now in development for HER2-overexpressing breast cancer treatment. The purpose of this study was to systematically collate all published clinical data to assess the weight of available evidence for TRAS biosimilars in HER2-positive (+) breast cancer (BC), and to identify additional studies, not captured in the scientific literature, to support informed decision-making by healthcare stakeholders, as well as to raise awareness of ongoing developments within the field. Methods: MEDLINE®, Embase® and ISI Web of Science® were searched from inception to Sept 3, 2015. Conference proceedings (n=17) were searched from 2012 to Jul 31, 2015. Studies disclosing potential use of proposed biosimilars in the treatment of HER2+ BC were screened and categorized by originator and study type (English language only). To assess data strength and validity, risk of bias assessments were conducted. The ClinicalTrials.gov (CT.gov) registry was searched to identify any planned/ongoing/complete biosimilar trials in HER2+ BC. Results: On the analysis cut-off date, a total of 7 clinical studies (12 publications) were identified for proposed biosimilars of TRAS. The biosimilars identified for TRAS with published clinical data were BCD-022, CT-P6, FTMB and PF-05280014. For BCD-022, a pharmacokinetics (PK)/safety study in HER2+ BC (N=46) evaluating BCD-022 compared to TRAS, demonstrated equivalence between the two treatments. A PK/safety study (N=174) and comparative safety/efficacy study (N=475) of CT-P6 in HER2+ BC patients both provided evidence of PK equivalence, safety, and efficacy of the proposed biosimilar in this patient population. Bioequivalence of FTMB (versus TRAS) was also reported based on the results of a PK/safety study (N=118) in healthy subjects. For PF-05280014, a PK/safety study (N=105) in healthy volunteers demonstrated equivalence with TRAS. One published comparative safety/efficacy study protocol for PF-05280014 versus TRAS was identified for first-line treatment of patients with HER2+ BC (estimated [E]:N=690), and a second PK/efficacy/safety protocol for neoadjuvant BC treatment (E:N=220) was also published. A number of other planned studies were identified in CT.gov. These included 4 comparative safety/efficacy studies in HER2+ BC evaluating ABP 980 (E:N=808), CT-P6 (N=383/N=532), SB3 (E:N=806) and 2 PK/safety studies (BCD-022 [E:N=206], CT-P6 [E:N=174]) in women with BC. Two studies investigating PK and safety in healthy volunteers were also identified (PF-05280014 [E:N=162], SB3 [E:N=109]). Conclusions: This systematic review provides an unbiased synthesis of available evidence for proposed TRAS biosimilars in HER2+ BC, including data to support clinical similarity. The available clinical data for the 4 proposed biosimilars (BCD-022, CT-P6, FTMB and PF-05280014) investigated in a total of 918 healthy subjects or patients indicated highly comparable PK, safety, or efficacy profiles, versus TRAS. Additional data are required to fully evaluate the clinical similarity for proposed TRAS biosimilars, and the completion of several ongoing comparative trials are expected to provide further assurance of safety and efficacy in specific patient populations. Citation Format: Jacobs I, Isakov L, Vana AM, Coiro J, Zacharchuk C, Ewesuedo R. Systematic review of clinical trials for monoclonal antibody biosimilars in HER2-positive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-19.

Trastuzumab, non-pegylated liposomal-encapsulated doxorubicin and paclitaxel in the neoadjuvant setting of HER-2 positive breast cancer.

Neoadjuvant treatment based on the combination of trastuzumab plus chemotherapy is the standard of care in patients with HER2-positive early or locally advanced breast cancer. The concurrent use of trastuzumab, anthracyclines and taxanes is frequently used in this setting despite the potential cardiotoxicity of both anthracyclines and trastuzumab. However, not much information is available about this chemotherapy scheme. We wanted to evaluate the efficacy and safety profile of the combination of trastuzumab, liposome-encapsulated doxorubicin and paclitaxel as neoadjuvant scheme. We also tried to establish predictive factors of pathologic complete response. The study was carried out in a tertiary University Hospital of Spain. This is a descriptive study of the clinical practice performed in our hospital. Efficacy was measured in terms of pathologic complete response, which was defined as the absence of invasive cancer cells in the breast and the axilla after neoadjuvant treatment. Thirty patients were included, the median age was 48. Seventeen (56.7 %) were hormonal receptor (HR) positive, 14 (46.6 %) had IIIa-b clinical stage and one of them had inflammatory breast cancer. 12 patients (40 %) achieved pCR. Patients with HR-negative BC achieved a higher pCR rate than those ones with HR-positive BC (61.5 % and 23.5 %, respectively; p value = 0.035). 21 patients (70 %) underwent breast conservative surgery. The treatment was in general well tolerated, most frequent grade 3-4 adverse events were neutropenia (20 %), asthenia and liver enzyme alteration (10 %) and febrile neutropenia (6.7 %). No patient developed heart failure, but one (3.3 %) presented a 10 % asymptomatic absolute reduction in left ventricular fraction ejection. The studied treatment for the neoadjuvant setting of HER2 positive breast cancer seems to be an effective therapeutic option. Despite the expected high rate of cardiotoxicity of this regimen, the study results shows that this treatment regimen appears to be safe. The combination of trastuzumab, non-pegylated liposomal-encapsulated doxorubicin and paclitaxel should be considered for the treatment of HER2-overexpressing breast cancer.

The potential utility of acetyltanshinone IIA in the treatment of HER2-overexpressed breast cancer: Induction of cancer cell death by targeting apoptotic and metabolic signaling pathways

Increased lipogenesis and protein synthesis is a hallmark of cancer cell proliferation, survival, and metastatic progression and is under intense investigation as a potential antineoplastic target. Acetyltanshinone IIA (ATA) is a compound that was obtained from chemical modifications of tanshinone IIA (TIIA), a potent anticancer agent extracted from the dried roots of the Chinese herbal medicine Salvia miltiorrhiza Bunge. A previous investigation indicated that ATA is more effective in inhibiting the growth of breast cancer especially cells with HER2 overexpression. However, the molecular mechanism(s) mediating this cytotoxic effect on HER2-positive breast cancer remained undefined. Studies described here report that ATA induced G1/S phase arrest and apoptosis in the HER2-positive MDA-MB-453, SK-BR-3, and BT-474 breast cancer cell lines. Mechanistic investigations revealed that the ATA-induced apoptosis effect is associated with remarkably down-regulation of receptor tyrosine kinases (RTKs) EGFR/HER2 and inhibition of their downstream pro-survival signaling pathways. Interestingly, ATA was found to trigger oxidative and endoplasmic reticulum (ER) stresses and to activate AMP activated protein kinase (AMPK) leading to inactivation of key enzymes involved in lipid and protein biogenesis. Intraperitoneal administration of ATA significantly inhibited the growth of MDA-MB-453 xenografts in athymic mice without causing weight loss and any other side effects. Additionally, transwell migration, invasion, and wound healing assays revealed that ATA could suppress tumor angiogenesis in vitro. Taken together, our data suggest that ATA may have broad utility in the treatment of HER2-overexpressed breast cancers.

Targeted delivery of CXCR4-siRNA by scFv for HER2+ breast cancer therapy

Therapeutics based on short interfering RNAs (siRNAs) have great potential to treat human diseases. However, the clinical application of siRNAs has been limited by their poor intracellular uptake, low serum stability, and inability to target specific cells. In this study, we addressed this lack of specificity by synthesizing a molecularly targeted CXCR4-siRNA (CXCR4si) for the treatment of HER2+ breast cancers using a HER2-scFv-arginine nonamer peptide fusion protein (e23sFv-9R) as an siRNA carrier. The e23sFv-9R binding siRNA is able to specifically deliver the siRNA to HER2+ breast cancer cells and concentrate and persist in orthotopic HER2+ breast cancer xenografts for at least 36 h. CXCR4si delivered by e23sFv-9R inhibited CXCR4 gene expression, reduced proliferation and metastasis and induced apoptosis in the HER2+ breast cancer BT-474 cell line in vitro. Moreover, the systemic delivery of CXCR4si by e23sFv-9R is able to suppress tumor growth, reduce metastasis and prolong survival in mice bearing HER2+ xenografts. This approach causes no systemic toxicity and does not activate the innate immune response, suggesting that a fusion protein carrying CXCR4si shows promise in the treatment of HER2-overexpressing breast cancer.

CD44 expression contributes to trastuzumab resistance in HER2-positive breast cancer cells.

Resistance to HER2-targeted therapies remains a major obstacle in the treatment of HER2-overexpressing breast cancer. CD44, a putative breast cancer stem cell (CSC) marker, is overexpressed in trastuzumab-resistant breast cancer cells. While CSC-related genes may play a role in the development of trastuzumab resistance, conflicting results have been published about CSC response to trastuzumab. We hypothesized that CD44 contributes to trastuzumab resistance independently of its role as a CSC marker. We used trastuzumab-sensitive breast cancer cell lines and their trastuzumab-resistant isogenic counterparts to evaluate the role of CD44 in response to trastuzumab. miRNA and mRNA expression were analyzed using microarray chips. A gene set enrichment analysis was created and matched with response to trastuzumab in cells and patient samples. The proportions of CSC in trastuzumab-resistant cells were similar to or lower than in the trastuzumab-sensitive cells. However, CD44 expression levels were significantly higher in both trastuzumab-resistant cell lines and its knockdown led to an increased response to trastuzumab. The invasiveness and anchorage-independent growth of trastuzumab-resistant cells were higher and blocked by downregulation of CD44. Results also showed that CD44-related resistance to trastuzumab is regulated by miRNAs. We identified a CD44-related gene expression profile that correlated with response to trastuzumab in cell lines and breast cancer patients. CD44 mediates trastuzumab resistance in HER2-positive breast cancer cells independently of its role as a CSC marker and that this role of CD44 is partly regulated by miRNA.