Pt(IV) hybrids containing a TDO inhibitor serve as potential anticancer immunomodulators

Area of Science:

• Biochemistry
• Immunology
• Oncology

Background:

• Tryptophan 2,3-dioxygenase (TDO) is an immunosuppressive enzyme implicated in tumor immune evasion and tolerance.
• Inhibiting TDO can enhance anti-tumor immunity and improve the efficacy of chemotherapy.
• Developing strategies to combine TDO inhibition with chemotherapy is crucial for overcoming tumor immune suppression.

Purpose of the Study:

• To develop a novel platinum(IV) complex incorporating a TDO inhibitor to reverse tumor immune suppression.
• To evaluate the anti-cancer activity and mechanism of action of the synthesized complex.
• To assess the complex's ability to modulate the immune microenvironment and enhance T-cell responses.

Main Methods:

• Synthesis and characterization of a mono-modified Pt(IV) complex (complex 3) containing a TDO inhibitor.
• Assessment of antitumor activity against human liver cancer cells.
• Flow cytometry analysis to determine cell death pathways and cell cycle arrest.
• Evaluation of T-cell immune responses and inhibition of TDO/kynurenine/AHR pathway.

Main Results:

• Complex 3 demonstrated significant antitumor activity against human liver cancer cells.
• Flow cytometry revealed that complex 3 induces mitochondrial-dependent apoptosis and S-phase cell cycle arrest.
• Complex 3 effectively enhanced T-cell immune responses by inhibiting TDO expression, reducing kynurenine production, and inactivating the aryl hydrocarbon receptor (AHR) pathway.

Conclusions:

• The developed Pt(IV) complex (complex 3) is a promising candidate for cancer therapy by combining direct anti-cancer effects with immune modulation.
• This strategy effectively reverses tumor immune suppression, offering a potential new avenue for treating liver cancer.
• Inhibiting the TDO pathway with complex 3 holds potential for enhancing anti-tumor immunity and overcoming therapeutic resistance.