Mitochondrial activation chemicals synergize with surface receptor PD-1 blockade for T cell-dependent antitumor...

Area of Science:

• Immunology
• Cancer Biology
• Metabolic pathways

Background:

• PD-1 blockade immunotherapy has improved cancer patient survival but requires enhanced efficacy for less responsive individuals.
• Tumor-reactive cytotoxic T lymphocytes (CTLs) in draining lymph nodes (DLNs) exhibit increased mitochondrial mass and reactive oxygen species (ROS) during PD-1 blockade therapy.

Purpose of the Study:

• To investigate the role of ROS and mitochondrial metabolism in CTL function during PD-1 blockade therapy.
• To explore novel combinatorial strategies to enhance the efficacy of PD-1 blockade immunotherapy.

Main Methods:

• Utilized mouse models of PD-1 blockade therapy.
• Administered ROS precursors or mitochondrial uncouplers to assess synergistic effects.
• Analyzed CTL expansion, activation markers (mTOR, AMPK), and transcription factors (PGC-1α, T-bet) in DLNs and tumors.
• Tested direct activators of mTOR, AMPK, and PGC-1α.

Main Results:

• ROS generation synergized PD-1 blockade, leading to effector/memory CTL expansion in DLNs and tumors.
• Activated CTLs showed increased mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), PPAR-gamma coactivator 1α (PGC-1α), and T-bet.
• Direct activation of mTOR, AMPK, or PGC-1α also synergized PD-1 blockade therapy.
• Tested compounds alone did not affect tumor growth.

Conclusions:

• Modulating ROS and mitochondrial metabolism enhances CTL responses against tumors during PD-1 blockade.
• Targeting metabolic pathways like mTOR, AMPK, and PGC-1α alongside PD-1 blockade offers a promising strategy for combinatorial cancer therapy.