A substantial number of
colon cancer patients do not benefit from
immunotherapy using programmed cell death 1 (PD1)
antibodies. Therefore, combination
therapy drugs are required to improve the efficacy of
colon cancer immunotherapy. Recent studies have shown that
deubiquitinases are negative regulators of anti-tumour immunity. In the present study, we investigated the effect of the
deubiquitinase inhibitor
PR-619 in combination with anti-PD1 for the treatment of
colorectal cancer. The results revealed that co-treatment with
PR-619 and anti-PD1 significantly inhibited tumour growth in tumour-bearing BALB/c mice compared to monotherapy with a single
drug. In addition, PR-619/anti-PD1 combined
therapy inhibited cell proliferation, promoted cell apoptosis, induced intratumor infiltration of CD8+ T cells, and enhanced the release of anti-tumour
cytokines. Moreover,
PR-619 induced ferroptosis in
colon cancer cells, thereby inducing the release of damage-associated molecular patterns that triggered anti-tumour immunity. Finally, we discovered that
PR-619 could degrade the GPX4
protein, the high expression of which was associated with poor prognosis and blocked CD8+ T cells infiltration in
colon cancer. In conclusion,
PR-619 may potentiate
immunotherapy by inducing ferroptosis, and thereby promoting CD8+ T cells-mediated anti-tumour immunity, providing a potential strategy for
colon cancer treatment.