Pharmacological rescue of mutant p53 triggers spontaneous tumor regression via immune responses

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• The tumor suppressor p53 is frequently mutated in cancer.
• Mutant p53 has potential immune-modulating capabilities for cancer treatment.
• Targeting reactivated p53 offers a novel therapeutic strategy.

Purpose of the Study:

• To investigate the efficacy of pharmacological p53 reactivation in treating spontaneous tumors.
• To elucidate the underlying immune mechanisms of mutant p53 reactivation.
• To assess the therapeutic potential of p53 reactivation in immunotherapy.

Main Methods:

• Utilized the p53 R279W mouse model for spontaneous tumor studies.
• Administered arsenic trioxide (ATO) via drinking water.
• Evaluated tumor regression, survival rates, and interferon (IFN) response.
• Used immunodeficient and T-cell-depleted allograft models.
• Tested ATO in human cancer cells and patient-derived samples.

Main Results:

• ATO treatment significantly prolonged survival in p53 R279W mice, dependent on p53 reactivation.
• 70% of ATO-treated mice showed transient T-lymphoma regressions with IFN response.
• Tumor suppression by reactivated p53 was reduced in immunodeficient and CD8+ T-cell-depleted mice.
• ATO activated the IFN pathway in human cancer cells and patient samples with p53 mutations.

Conclusions:

• Pharmacological reactivation of mutant p53, exemplified by ATO, demonstrates therapeutic efficacy against spontaneous tumors.
• The anti-tumor effects are partially mediated by the immune system, specifically involving T-cells and IFN response.
• Mutant p53 represents a viable therapeutic target for developing novel immunotherapies.