Inhibiting PPM1D Perturbs Mitochondrial Integrity to Stimulate cGAS-STING Signaling and Antitumor Immunity.

Inhibiting PPM1D disrupts mitochondrial integrity, activates cGAS-STING signaling, and enhances antitumor immunity in hepatocellular carcinoma models.

• Why it matters: Overcoming resistance to immune checkpoint blockade (ICB) is critical for effective hepatocellular carcinoma (HCC) treatment, as current therapies often fail due to tumor immune evasion mechanisms.
• What they did: The study used genetic and pharmacological approaches to inhibit PPM1D in HCC, revealing its role in maintaining mitochondrial homeostasis and limiting immune activation by dephosphorylating VDAC2 at Ser 115.
• The result: Targeting PPM1D boosted CD8+ T-cell cytotoxicity, synergized with PD-1 blockade, and suppressed tumor progression with minimal toxicity, offering a promising strategy to improve immunotherapy outcomes.