PI3Kα/δ inhibition promotes anti-tumor immunity through direct enhancement of effector CD8⁺ T-cell activity

Area of Science:

• Immunology
• Pharmacology
• Oncology

Background:

• Phosphoinositide 3-kinase (PI3K) inhibitors target tumor cells, but their impact on the tumor immune microenvironment is less understood.
• PI3Kδ inhibition can reduce immunosuppression by regulatory T-cells (T-regs), while PI3K inhibitors can cause immune-related side effects.
• The effects of dual PI3Kα/δ inhibitors on tumor immunology remain largely unexplored.

Purpose of the Study:

• To investigate the effects of AZD8835, a dual PI3Kα/δ inhibitor, on the tumor immune microenvironment.
• To evaluate the anti-tumor activity and immunological mechanisms of AZD8835 in syngeneic mouse tumor models.
• To determine if continuous or intermittent dosing of AZD8835 is more effective.

Main Methods:

• Utilized syngeneic mouse tumor models to assess the impact of AZD8835 on the tumor immune microenvironment.
• Examined the anti-tumor activity and immune cell dynamics, including T-regs and CD8+ T-cells, under different dosing schedules.
• Analyzed effector T-cell viability and function following PI3Kα/δ inhibition.

Main Results:

• AZD8835 demonstrated significant single-agent anti-tumor activity, potentiated by intermittent dosing.
• PI3Kα/δ inhibition led to dynamic suppression of T-regs and enhanced CD8+ T-cell activation and memory.
• AZD8835 promoted robust CD8+ T-cell activation and effector cell function, independent of T-reg suppression.

Conclusions:

• AZD8835 exhibits potent anti-tumor effects through immunomodulation, enhancing effector T-cell responses.
• Intermittent dosing of AZD8835 optimizes anti-tumor activity, suggesting a novel therapeutic strategy.
• AZD8835 is validated as a potential immuno-oncology drug, warranting further clinical investigation.