Design, syntheses and evaluations of novel indole derivatives as orally selective estrogen receptor degraders (SERD)

The anti-breast cancer potential of indole/isatin hybrids

Breast cancer (BC) is one of the most prevalent malignancies and the major contributor to cancer mortality in women globally, with a high degree of heterogeneity and a dismal prognosis. As drug resistance is responsible for most BC fatalities and advanced BC is currently considered incurable, finding innovative anti-BC chemotherapeutics is urgently required. Indole and its analog isatin (indole-1H-2,3-dione) are prominent pharmacophores in the development of novel medications, and their derivatives exhibit strong anticancer activities, also against BC. In particular, indole/isatin hybrids exhibit significant potency against BC including multidrug-resistant forms and excellent selectivity by influencing a variety of biological targets associated with the disease, supplying helpful building blocks for the identification of potential new BC treatment options. This review includes articles from 2020 to the present and provides insights into the in vitro and in vivo anti-BC potential, molecular mechanisms, and structure-activity relationships (SARs) of indole/isatin hybrids that may be helpful in the development of innovative anti-BC chemotherapeutics.

Optimization of small molecule degraders and antagonists for targeting estrogen receptor based on breast cancer: current status and future

The estrogen receptor (ER) is a classical receptor protein that plays a crucial role in mediating multiple signaling pathways in various target organs. It has been shown that ER-targeting therapies inhibit breast cancer cell proliferation, enhance neuronal protection, and promote osteoclast formation. Several drugs have been designed to specifically target ER in ER-positive (ER+) breast cancer, including selective estrogen receptor modulators (SERM) such as Tamoxifen. However, the emergence of drug resistance in ER+ breast cancer and the potential side effects on the endometrium which has high ER expression has posed significant challenges in clinical practice. Recently, novel ER-targeted drugs, namely, selective estrogen receptor degrader (SERD) and selective estrogen receptor covalent antagonist (SERCA) have shown promise in addressing these concerns. This paper provides a comprehensive review of the structural functions of ER and highlights recent advancements in SERD and SERCA-related small molecule drugs, especially focusing on their structural optimization strategies and future optimization directions. Additionally, the therapeutic potential and challenges of novel SERDs and SERCAs in breast cancer and other ER-related diseases have been discussed.

Stereodivergent Zweifel Olefination and its Mechanistic Dichotomy

Stereoselective Zweifel olefination using boronate complexes carrying two different reactive π-systems was achieved to synthesize vinyl heteroarenes and conjugated 1,3-dienes in good yield and up to 100 % stereoselectivity, which remains unexplored until now. Most importantly, we report the unprecedented formation of E vs. Z-vinyl heteroarenes for different heteroarenes under identical conditions. Density functional theory (DFT) investigations unveil the mechanistic dichotomy between olefin and heteroarene activation followed by 1,2-migration, leading to E or Z-vinyl heteroarenes respectively. We also report a previously unknown reversal of stereoselectivity by using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electrophile. The Zweifel olefination using a boronate complex that carries two different olefins was previously unexplored due to significant challenges associated with the site-selective activation of olefins. We have solved this problem and reported the site-selective activation of olefins for the stereoselective synthesis of 1,3-dienes.

Selective Estrogen receptor degraders (SERDs) for the treatment of breast cancer: An overview

Discovery of SERDs has changed the direction of anticancer research, as more than 70% of breast cancer cases are estrogen receptor positive (ER+). Therapies such as selective estrogen receptor modulators (SERM) and aromatase inhibitors (AI's) have been effective, but due to endocrine resistance, SERDs are now considered essential therapeutics for the treatment of ER+ breast cancer. The present review deliberates the pathophysiology of SERDs from the literature covering various molecules in clinical trials. Estrogen receptors active sites distinguishing characteristics and interactions with currently available FDA-approved drugs have also been discussed. Designing strategy of previously reported SERDs, their SAR analysis, in silico, and the biological efficacy have also been summarized along with appropriate examples.

Selective estrogen receptor degraders (SERDs) and covalent antagonists (SERCAs): a patent review (2015-present)

INTRODUCTION

The estrogen receptor (ER) is a clinically validated oncology target with a pivotal role in hormonally driven breast cancer, the most prevalent form of female cancer. Current treatments which directly modulate ER include antagonists (SERMs), such as tamoxifen, and degraders (SERDs), such as fulvestrant which is administered by intramuscular injection.

AREAS COVERED

This review covers patent applications that claim estrogen receptor degraders (SERDs) and covalent antagonists (SERCAs) between the period January 2015 to June 2021. A total of 114 patent applications from 23 different applicants are evaluated with stratification into acidic SERDs, basic SERDs and SERCAs.

EXPERT OPINION

The clinical success of fulvestrant in the treatment of ER⁺ breast cancer has spurred research over the last decade into the discovery and development of novel SERDs, with a particular focus on the discovery of orally bioavailable drugs. This has resulted in a diverse range of candidates entering clinical trials. Although some have faltered in development, a cohort of oral SERDs has generated encouraging efficacy and safety data that has allowed advancement into late stage clinical trials. Data from these trials is eagerly awaited, with these molecules having the potential to offer significant benefits in the treatment of ER⁺ breast cancer.