Sex-differential responses to immune checkpoint inhibitors across the disease continuum unified by tumor mutational burden

While the efficacy of immune checkpoint inhibitors (ICIs) in advanced non–small-cell lung cancer (NSCLC) is well-established, sex-based differences in treatment responses remain insufficiently explored. This study examines how sex disparities impact ICI treatment outcomes in advanced-stage NSCLC, focusing on the role of tumor mutational burden (TMB) in these differences. This study analyzed data from 174 advanced-stage, chemotherapy-naïve, NSCLC patients treated with ICIs, including PD-1/PD-L1 and CTLA-4 inhibitors, to assess sex differences in treatment response and survival outcomes. Male patients with low TMB (<10 mut/Mb) had worse treatment responses compared to female patients. In contrast, no sex differences were observed in patients with high TMB, where both sexes exhibited similar therapeutic responses. These results suggest that high TMB may reduce the impact of sex on ICI efficacy, with male and female patients showing comparable outcomes. Furthermore, sex disparities in disease progression and overall survival were more evident in low-TMB patients, emphasizing the role of TMB in modulating sex-related differences in immunotherapy outcomes. This study highlights the importance of incorporating both sex and TMB into precision oncology. High TMB appears to equalize treatment responses between sexes, while low TMB may necessitate more personalized treatment strategies, particularly for male patients. Further research into the biological mechanisms underlying these differences is essential to optimize ICI therapies and enhance patient outcomes. Integrating both sex and TMB into clinical decision-making will help to develop more tailored and effective cancer immunotherapy.