Propafenone facilitates mitochondrial-associated ferroptosis and synergizes with immunotherapy in melanoma

Despite the successful application of immunotherapy, both innate and acquired resistance are typical in melanoma. Ferroptosis induction appears to be a potential strategy to enhance the effectiveness of immunotherapy. However, the relationship between the status of ferroptosis and the effectiveness of immunotherapy, as well as viable strategies to augment ferroptosis, remain unclear. In this study, through large-scale drug screening of cardiovascular drugs, we identified propafenone, an anti-arrhythmia medication, as capable of synergizing with ferroptosis inducers in melanoma. Furthermore, we observed that propafenone, in combination with RSL3, collaboratively induces mitochondrial-associated ferroptosis. Mechanistically, propafenone transcriptionally upregulates mitochondrial HMOX1 via activation of the JNK/JUN signaling pathway under RSL3 treatment, leading to overloaded ferrous iron and ROS within the mitochondria. In xenograft models, the combination of propafenone with ferroptosis induction led to nearly complete tumor regression. Consistently, propafenone enhances immunotherapy-induced antitumor immunity and tumoral ferroptosis in tumor-bearing mice. Significantly, patients exhibiting high levels of ferroptosis/JUN/HMOX1 exhibited improved efficacy of immunotherapy and prolonged progression-free survival. These findings suggest that propafenone holds promise as a candidate drug for enhancing the efficacy of immunotherapy and other ferroptosis-targeted therapies in the treatment of melanoma. Overall design: Immunocompetent C57BL/6 mice implanted with B16F10 melanoma cells received intra-peritoneal injections of anti-PD-1 treatment or IgG control with or without propafenone on the indicated day after the tumor reached approximately 100?mm3 and tumor were excised for RNA sequencing on day 16.