Tackling metastatic triple-negative breast cancer with sacituzumab govitecan

Understanding the promising role of antibody drug conjugates in breast and ovarian cancer

A nascent category of anticancer therapeutic drugs called antibody-drug conjugates (ADCs) relate selectivity of aimed therapy using chemotherapeutic medicines with high cytotoxic power. Progressive linker technology led to the advancement of more efficacious and safer treatments. It offers neoteric as well as encouraging therapeutic strategies for treating cancer. ADCs selectively administer a medication by targeting antigens which are abundantly articulated on the membrane surface of tumor cells. Tumor-specific antigens are differently expressed in breast and ovarian cancers and can be utilized to direct ADCs. Compared to conventional chemotherapeutic drugs, this approach enables optimal tumor targeting while minimizing systemic damage. A cleavable linker improves the ADCs because it allows the toxic payload to be distributed to nearby cells that do not express the target protein, operating on assorted tumors with dissimilar cell aggregation. Presently fifteen ADCs are being studied in breast and ovarian carcinoma preclinically, and assortment of few have already undergone promising early-phase clinical trial testing. Furthermore, Phase I and II studies are investigating a wide variety of ADCs, and preliminary findings are encouraging. An expanding sum of ADCs will probably become feasible therapeutic choices as solo agents or in conjunction with chemotherapeutic agents. This review accentuates the most recent preclinical findings, pharmacodynamics, and upcoming applications of ADCs in breast and ovarian carcinoma.

Selenium modulates AR/IGF-1R/EGFR and TROP2 signaling pathways and improves anticancer efficacy in murine mammary carcinoma 4T1

The micronutrient selenium (Se) has been shown to exert potential anticancer properties. This study aimed to evaluate the effects of Se (in Se yeast form) on the selenoproteins (SELENO), AR/IGF-1R/EGFR, PI3K/Akt/mTOR and Ras/Raf/ERK cascades, and immune checkpoint blockade in TNBC murine 4T1 cells. We also assessed the effects of combination treatment with chemotherapeutic doxorubicin and Se on trophoblast cell surface antigen 2 (TROP2) levels. Compared with the control groups, cells incubated with Se (0.25, 0.5, 0.75, 1.0, 1.5 µg Se/mL) have lower viability, raised intracellular Se concentrations and SELENO expression, and higher malondialdehyde products in a dose-dependent manner. Se induced the inactivation of AR/IGF-1R/EGFR and downregulation of the PI3K/Akt/mTOR and Ras/Raf/ERK signaling molecules. Se-treated cells also exhibited decreased mitochondrial membrane potential, reduced levels of the cell cycle regulatory protein cyclin D1, cancer stemness, metastatic and EMT-related markers, and increased apoptosis. Subsequently, Se treatment significantly suppressed PD-1/PD-L1 and CTLA-4 mRNA levels and proteins. Doxorubicin decreased 4T1 cell viability and TROP2 expression levels, but the addition of Se to doxorubicin contributed to further reductions. Similar responses to Se treatment were also observed in the human MDA-MB-231 and MCF-7 breast cancer cells. These results show that Se upregulates SELENO and anti-AR/IGF-1R/EGFR signaling in TNBC cells, thus inducing oxidative stress-dependent apoptosis and cell cycle arrest, stemness, EMT, and metastasis, as well as blocking the immune checkpoint molecules. TROP2 down-regulation with Se is also a potential anti-TNBC therapeutic target.

The emergence of targeted therapy for HER2-low triple-negative breast cancer: a review of fam-trastuzumab deruxtecan

INTRODUCTION

Metastatic triple-negative breast cancer (TNBC) is an aggressive sub-type of breast cancer. Despite recent advances, metastatic TNBC remains difficult to treat with limited targeted treatment options. Fam-trastuzumab deruxtecan (T-DXd), is a novel antibody-drug conjugate (ADC) targeting human epidermal growth factor receptor 2 (HER2) and is composed of a unique linker bound to the topoisomerase I inhibitor DXd. T-DXd has significant anti-tumor activity in patients with HER2-low TNBC.

AREAS COVERED

This review reports on the mechanism, pre-clinical/clinical studies, efficacy, and tolerability of T-DXd. A literature search was conducted via PubMed using keywords such as 'fam-trastuzumab deruxtecan,' 'Enhertu,' and 'HER2-low cancers.'

EXPERT OPINION

The Phase III Destiny-Breast04 Trial showed benefit in progression-free and overall survival in patients with HER2-low metastatic breast cancers treated with T-DXd compared to treatment of physician's choice chemotherapy. T-DXd is the first pharmaceutical to effectively target a HER2-low population with clinically meaningful efficacy in patients with HER2-low TNBC. Compared to chemotherapy, T-DXd has a similar safety profile, with the additional need for close monitoring for interstitial lung disease. Given the clinical activity of T-DXd in TNBC, it is likely there will be continued efforts to refine HER2-low diagnostics and to develop additional ADCs with other protein targets.

Unveiling the antibody-drug conjugates portfolio in battling Triple-negative breast cancer: Therapeutic trends and Future horizon

Triple-negative breast cancer (TNBC) showcases a labyrinthine network exhibiting deficient expression of Estrogen receptor (ER), Progesterone receptor (PR), and Human-epidermal growth factor receptor-2 (HER2). This restricts the conventional chemotherapeutic, hormonal, and few targeted regimens in showing efficient anti-tumor response. Antibody-drug conjugates (ADCs) are target-specific conjugates comprising a monoclonal antibody attached to the desired cytotoxic payload with the support of a stable linker. They are designated as one of the encouraging sets of targeted therapies that have unveiled affirmative outcomes owing to increased specificity in targeting the undetectable or deficiently expressed targets. Another virtue of ADCs lending superiority to this approach is the presence of inherent bystander effect which has a detrimental influence on the tumor microenvironment (TME) devoid of antigen expression. In the current scenario, FDA-approved Sacituzumab govitecan is widely being utilized to mitigate TNBC while many other ADCs are being studied in clinical trials. Additionally, a focus has been set on revelation of application of Trastuzumab deruxtecan in HER2-low metastatic breast cancer which widens the current therapeutic horizon dealing with such carcinomas. After making an effort towards sketching ADCs profile, we conclude that this novel approach deserves to be investigated through future campaigns owing to its remarkable bystander effect, ability to precisely recognize the antigen and spare the naïve cells from detrimental toxicity. Exploration of the remarkable potential of Sacituzumab govitecan in multiple indications including TNBC portrays the prominence of ADCs and prompts the bright future of this therapeutic approach. In this review, we present the basic foundation of ADCs alongside summarizing the building blocks of several ADCs used in TNBC. Furthermore, by shedding light on the therapeutic regimens and concomitant effects of various ADCs derived from the supportive backbone of clinical trials, we have attempted to convene several segments of ADCs and portray their potentialities time ahead.

Addiction of Cancer Stem Cells to MUC1-C in Triple-Negative Breast Cancer Progression

Triple-negative breast cancer (TNBC) is an aggressive malignancy with limited treatment options. TNBC progression is associated with expansion of cancer stem cells (CSCs). Few insights are available regarding druggable targets that drive the TNBC CSC state. This review summarizes the literature on TNBC CSCs and the compelling evidence that they are addicted to the MUC1-C transmembrane protein. In normal epithelia, MUC1-C is activated by loss of homeostasis and induces reversible wound-healing responses of inflammation and repair. However, in settings of chronic inflammation, MUC1-C promotes carcinogenesis. MUC1-C induces EMT, epigenetic reprogramming and chromatin remodeling in TNBC CSCs, which are dependent on MUC1-C for self-renewal and tumorigenicity. MUC1-C-induced lineage plasticity in TNBC CSCs confers DNA damage resistance and immune evasion by chronic activation of inflammatory pathways and global changes in chromatin architecture. Of therapeutic significance, an antibody generated against the MUC1-C extracellular domain has been advanced in a clinical trial of anti-MUC1-C CAR T cells and in IND-enabling studies for development as an antibody–drug conjugate (ADC). Agents targeting the MUC1-C cytoplasmic domain have also entered the clinic and are undergoing further development as candidates for advancing TNBC treatment. Eliminating TNBC CSCs will be necessary for curing this recalcitrant cancer and MUC1-C represents a promising druggable target for achieving that goal.

Synthesis and evaluation of highly releasable and structurally stable antibody-SN-38-conjugates

Camptothecins, traditional chemotherapy drugs, have been clinically used in antibody-drug conjugates (ADCs), which refreshes the recognition that ADCs preferably incorporate highly potent payloads. However, SN-38, active metabolite of irinotecan from camptothecins, tended to be incorporated into ADCs with an unstable acid sensitive bond, not with the widely used Cathepsin B (CTSB) sensitive bond, which may pose the risk of off-target. Herein, we reported a novel strategy to construct highly releasable and structurally stable SN-38-conjugates, in which CTSB linkers directly connected to the 10-OH group through ether bond, not to the common 20-OH group of lactones of SN-38. In this paper, rapid release of SN-38 was skillfully demonstrated by utilizing the fluorescence properties of SN-38. The SN-38-ether-ADC displayed highly stable serum stability with the half-life over 10 days. Moreover, the drug-antibody-ratio (DAR) of ADC could be elevated to 7.1 through the introduction of polyethylene glycol (PEG) moieties without aggregation. The optimized ADC exhibited potent in vitro activities up to 5.5 nM, comparable to SN-38. Moreover, this ADC group significantly delayed tumor growth in vivo. In conclusion, the novel strategy has the potential to promote the development of SN38-ADCs and enrich the conjugation approaches for hydroxyl-bearing payloads.