Synthesis of MDM2-p53 Inhibitor BI-0282 via a Dipolar Cycloaddition and Late-Stage Davis–Beirut Reaction

Targeting MDM2-p53 interaction for breast cancer therapy

Breast cancer is a significant global concern, with limited effective treatment options. Therefore, therapies with high efficacy and low complications, unlike the existing chemotherapies, are urgently required. To address this issue, advances have been made in therapies targeting molecular pathways related to the murine double minute 2 proto-oncogene (MDM2)-tumor proteinp53 (TP53) interaction. This review aims to investigate the efficacy of MDM2 inhibition in restoring TP53 activity in breast cancer cells, as evidenced by clinical studies, reviews, and trials. TP53 is a tumor suppressor and MDM2 facilitates proteasomal degradation of TP53. MDM2 and TP53 activity is tightly regulated. However, cancerous breast cells overexpress MDM2 through five hypothesized mechanisms. Consequently, TP53 levels decrease with increased tumor cell proliferation. Three strategies have been identified for controlling MDM2 upregulation in cells with wild-type or mutated TP53. MDM2 inhibitors (MDM2i) are administered in combination with existing chemotherapies to reduce their effects on healthy cells. Few clinical and preclinical studies have been conducted using MDM2i, which necessitates high-quality clinical trials to support their therapeutic potential in breast cancer therapy.

Discovery and Characterization of Brigimadlin, a Novel and Highly Potent MDM2-p53 Antagonist Suitable for Intermittent Dose Schedules

p53 is known as the guardian of the genome and is one of the most important tumor suppressors. It is inactivated in most tumors, either via tumor protein p53 (TP53) gene mutation or copy number amplification of key negative regulators, e.g., mouse double minute 2 (MDM2). Compounds that bind to the MDM2 protein and disrupt its interaction with p53 restore p53 tumor suppressor activity, thereby promoting cell cycle arrest and apoptosis. Previous clinical experience with MDM2-p53 protein-protein interaction antagonists (MDM2-p53 antagonists) has demonstrated that thrombocytopenia and neutropenia represent on-target dose-limiting toxicities that might restrict their therapeutic utility. Dosing less frequently, while maintaining efficacious exposure, represents an approach to mitigate toxicity and improve the therapeutic window of MDM2-p53 antagonists. However, to achieve this, a molecule possessing excellent potency and ideal pharmacokinetic properties is required. Here, we present the discovery and characterization of brigimadlin (BI 907828), a novel, investigational spiro-oxindole MDM2-p53 antagonist. Brigimadlin exhibited high bioavailability and exposure, as well as dose-linear pharmacokinetics in preclinical models. Brigimadlin treatment restored p53 activity and led to apoptosis induction in preclinical models of TP53 wild-type, MDM2-amplified cancer. Oral administration of brigimadlin in an intermittent dosing schedule induced potent tumor growth inhibition in several TP53 wild-type, MDM2-amplified xenograft models. Exploratory clinical pharmacokinetic studies (NCT03449381) showed high systemic exposure and a long plasma elimination half-life in patients with cancer who received oral brigimadlin. These findings support the continued clinical evaluation of brigimadlin in patients with MDM2-amplified cancers, such as dedifferentiated liposarcoma.

Synthesis of Complex Tetracyclic Fused Scaffolds Enabled by (3 + 2) Cycloaddition

We describe the single-step formation of complex tetracyclic fused scaffolds enabled by (3 + 2) cycloaddition of azomethine ylides. Various indoles, N-protecting groups, and amino acids are well tolerated. The products are obtained in a catalyst-free manner with moderate to excellent yield and high diastereoselectivity. Representing a new scaffold that is not yet found in nature, the construction of pyrrolidine-fused cyclohepta-, azepino-, or oxepinoindoles could be found valuable in the synthesis of new pseudo-natural products.

Insight on Heterocycles as p53‐MDM2 Protein‐Protein Interaction Inhibitors: Molecular Mechanism for p53 Activation

Transcription factor p53, also known as tumor suppressor protein. Encoded by the TP53 gene, the guardian of genome p53 regulates many gene pathways. Nevertheless, the molecular mechanisms of p53 functioning have been known for a few decades, and the exact role of p53 in cancer therapy is unclear. Also, comprehensive literature on heterocycles as p53‐MDM2 protein‐protein interaction inhibitors is limited. This review covers the molecular mechanism for the p53‐MDM2 interaction and its inhibition by the heterocyclic small molecules. We hope the present comprehensive study will help to develop heterocycles as anticancer drugs that induce apoptosis in tumor cells.