HLA loss of heterozygosity-mediated discordant responses to immune checkpoint blockade in squamous cell lung cancer with renal metastasis.

Despite the significant success of immune checkpoint blockade therapy in advanced non-small-cell lung cancer compared with chemotherapy, efficacy varies greatly across patients, and acquired resistance frequently occurs. In particular, during immunotherapy, the dynamic changes in molecular events have not been characterized. The authors report a case of squamous cell lung carcinoma with renal metastasis, treated with pembrolizumab, in which the primary tumor and rare renal metastases showed different responses. Using whole-exome sequencing, the authors found loss of heterogeneity in HLA genes in all tumors and high levels of intratumor heterogeneity in metastases. The increased levels of HLA loss led to therapy resistance during tumor evolution. In addition to tumor mutational burden and PD-L1, HLA loss of heterozygosity and intratumor heterogeneity should be taken into consideration during immunotherapy.