Synergistic antitumor efficacy against the EGFRvIII+HER2+ breast cancers by combining trastuzumab with anti-EGFRvIII antibody CH12

α-chaconine increases the sensitivity of HER2+ breast cancer cells to trastuzumab by targeting acetylcholinesterase

BACKGROUND

Trastuzumab (TRZ) is the first drug used to treat HER2-positive breast cancer, but some patients become resistant to it because of the PI3K/Akt pathway and other pathways that counteract it. TRZ, in conjunction with other therapeutic agents, is needed to overcome resistance. α-chaconine (CHA), a glycoalkaloid from the Solanaceae family, can suppress lung cancer cell proliferation in vitro by inhibiting PI3K/Akt signaling, one of the key regulatory pathways in TRZ resistance.

METHODS

This study used integrative bioinformatics analysis to screen for possible targets of CHA that can help fight breast cancer that is resistant to TRZ. In vitro experiments were used to confirm the target genes using TRZ-resistant HCC-1954 (HCC-TRZ) cells for cytotoxicity, gene expression studies, and enzymatic assay.

RESULTS

We identified several potential target genes of CHA, including EGFR, VEGF, ACHE, and ADORA. We generated HCC1954-TRZ cells, which showed an increase in cell viability after sequential treatment of the parental HCC1954 cells with TRZ. Further experiments showed the high sensitivity of HCC-TRZ toward TRZ when TRZ was combined with CHA. The combination of CHA and TRZ significantly increased the mRNA expression levels of various genes compared to a single TRZ treatment. Additionally, CHA alone and combined with CHA-TRZ inhibited acetylcholinesterase (AChE) activity in HCC-TRZ cells.

CONCLUSION

CHA increased the sensitivity of HCC-TRZ cells to TRZ by targeting several potential target genes and AChE activity. This study highlights the potential of using CHA in combination with TRZ to overcome TRZ resistance in HER2+ breast cancer cells.

TSR-033, a Novel Therapeutic Antibody Targeting LAG-3, Enhances T-Cell Function and the Activity of PD-1 Blockade In Vitro and In Vivo

Progressive upregulation of checkpoints on tumor-infiltrating lymphocytes promotes an immunosuppressive tumor microenvironment, severely compromising tumor immunity. Lymphocyte activation gene-3 (LAG-3) is a coinhibitory receptor associated with impaired T-cell function and is frequently coexpressed with programmed cell death protein-1 (PD-1) in the context of human cancers. Targeting LAG-3 in conjunction with PD-1 thus represents a strategy to amplify and broaden the therapeutic impact of PD-1 blockade alone. We have generated a high affinity and selective humanized monoclonal IgG4 antibody, TSR-033, which binds human LAG-3 and serves as a functional antagonist, enhancing in vitro T-cell activation both in mixed lymphocyte reactions and staphylococcal enterotoxin B-driven stimulation assays. In a humanized mouse non-small cell lung carcinoma model, TSR-033 boosted the antitumor efficacy of PD-1 monotherapy, with a concomitant increase in immune activation. Analogous studies in a murine syngeneic tumor model using surrogate antibodies demonstrated significant synergy between LAG-3 and PD-1 blockade-combination treatment led to a marked improvement in therapeutic efficacy, increased T-cell proliferation, IFNγ production, and elicited durable immunologic memory upon tumor rechallenge. Taken together, the pharmacologic activity of TSR-033 demonstrates that it is a potent anti-LAG-3 therapeutic antibody and supports its clinical investigation in cancer patients.

Aptamer-conjugated PEGylated quantum dots targeting epidermal growth factor receptor variant III for fluorescence imaging of glioma

The extent of resection is a significant prognostic factor in glioma patients. However, the maximum safe resection level is difficult to determine due to the inherent infiltrative character of tumors. Recently, fluorescence-guided surgery has emerged as a new technique that allows safe resection of glioma. In this study, we constructed a new kind of quantum dot (QD)-labeled aptamer (QD-Apt) nanoprobe by conjugating aptamer 32 (A32) to the QDs surface, which can specially bind to the tumors. A32 is a single-stranded DNA capable of binding to the epidermal growth factor receptor variant III (EGFRvIII) specially distributed on the surface of glioma cells. To detect the expression of EGFRvIII in human brain tissues, 120 specimens, including 110 glioma tissues and 10 normal brain tissues, were examined by immunohistochemistry, and the results showed that the rate of positive expression of EGFRvIII in the glioma tissues was 41.82%, and 0.00% in normal brain tissues. Besides, the physiochemical properties of QD-Apt nanoparticles (NPs) were thoroughly characterized. Biocompatibility of the NPs was evaluated, and the results suggested that the QD-Apt was nontoxic in vivo and vitro. Furthermore, the use of the QD-Apt in labeling glioma cell lines and human brain glioma tissues, and target gliomas in situ was also investigated. We found that not only could QD-Apt specially bind to the U87-EGFRvIII glioma cells but also bind to human glioma tissues in vitro. Fluorescence imaging in vivo with orthotopic glioma model mice bearing U87-EGFRvIII showed that QD-Apt could penetrate the blood-brain barrier and then selectively accumulate in the tumors through binding to EGFRvIII, and consequently, generate a strong fluorescence, which contributed to the margins of gliomas that were visualized clearly, and thus, help the surgeons realize the maximum safe resection of glioma. In addition, QD-Apt can also be applied in preoperative diagnosis and postoperative examination of glioma. Therefore, these achievements facilitate the use of tumor-targeted fluorescence imaging in the diagnosis, surgical resection, and postoperative examination of glioma.

A brief perspective of drug resistance toward EGFR inhibitors: the crystal structures of EGFRs and their variants

The EGFR is one of the most popular targets for anticancer therapies and many drugs, such as erlotinib and gefitinib, have got enormous success in clinical treatments of cancer in past decade. However, the efficacy of these agents is often limited because of the quick emergence of drug resistance. Fundamental structure researches of EGFR in recent years have generally elucidated the mechanism of drug resistance. In this review, based on systematic resolution of full structures of EGFR and their variants via single crystal x-ray crystallography, the working and drug resistance mechanism of EGFR-targeted drugs are fully illustrated. Moreover, new strategies for avoiding EGFR drug resistance in cancer treatments are also discussed.