A triple-action PROTAC for wild-type p53 cancer therapy

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• p53 suppression is crucial in cancer, but therapeutic reactivation faces efficacy and toxicity challenges.
• Existing therapies like targeted and combination chemotherapies have limitations in treating wild-type p53 cancers.
• Proteolysis targeting chimeras (PROTACs) offer a promising avenue for targeted protein degradation.

Purpose of the Study:

• To develop a novel therapeutic strategy for reactivating p53 in cancer.
• To introduce a triple-action proteolysis targeting chimera (TAPTAC) to overcome limitations of current cancer therapies.
• To evaluate the efficacy and safety of TAPTAC1 in preclinical cancer models.

Main Methods:

• Design and synthesis of TAPTAC1, a molecule engineered to simultaneously target multiple oncogenic pathways.
• In vitro and in vivo studies using cancer cell lines and mouse models (osteosarcoma, leukemia) with wild-type p53.
• Comparative analysis of TAPTAC1 against existing combination treatments and single-target PROTACs.

Main Results:

• TAPTAC1 effectively reactivates p53 by diverting HDM2 from p53 degradation and eliminating oncogenic BET proteins.
• TAPTAC1 blocks HDMX-mediated p53 sequestration, enhancing p53 reactivation and apoptosis.
• TAPTAC1 demonstrated superior efficacy and reduced toxicity compared to combination therapies and HDM2/BET-targeting PROTACs in WT p53 cancers.
• The drug leverages cancer's dependency on HDM2 for enhanced selectivity and safety.

Conclusions:

• TAPTACs represent a promising therapeutic platform for treating wild-type p53 cancers, addressing limitations of prior strategies.
• TAPTAC1 offers a novel approach to simultaneously target multiple oncogenic mechanisms for effective cancer therapy.
• The broad applicability in pediatric and adult cancers with retained WT p53 highlights the potential of TAPTACs.