Analysis of LRP1B as a potential biomarker for colorectal cancer immunotherapy.

e15521 Background: Low-density lipoprotein receptor-related protein 1B (LRP1B), a putative tumor suppressor, is one of the most frequently altered gene in cancer. Recently, there are emerging evidences that LRP1B is involved in sensitivity to melanoma and non-small cell lung cancer immunotherapy. Here we explored the relationship between LRP1B mutation and potential effect of immunotherapy for colorectal cancer (CRC) based on multidimensional data. Methods: Next-generation sequencing (NGS) data of CRC patients (n = 536) from TCGA and Chinese clinical dataset (n = 249) was used to evaluate tumor mutational burden (TMB) differences between LRP1B mutation group and wildtype group. TMB was calculated as the total count of nonsynonymous mutations in coding sequence. Neoantigens of CRC samples (n = 214) were obtained from The Cancer Immunome Atlas. In addition, we investigated the association of LRP1B mutation with 30 immune-related genes, which were classified into 3 categories: immune checkpoint, T-effector and interferon-γ gene signature, and T cell receptor. Results: 22.95% (123/536) patients in TCGA harbored LRP1B mutation. In the Chinese cohort, the LRP1B mutation ratio (24.50%, 61/249) was similar to TCGA. The TMB level of LRP1B mutation group in both TCGA and Chinese cohort was significantly higher than wild-type group (P < 0.001). The TNB between two group is also showed a significant difference (P < 0.001) in TCGA. Of the 30 immune-related genes, 27 (90.0%) genes are differentially expressed (P < 0.05) and all 27 differentially expressed genes have higher expression levels in LRBP1-mutated samples in comparison with wild-type ones. Conclusions: LRBP1-mutated CRC patients have a higher TMB, TNB and show higher expression level with immune-related genes. These results indicated that LRP1B mutation may serve as a potential biomarker of ICI benefit in CRC patients. Moreover, further clinical insights and prospective validation studies are warranted.