RB1 mutation had influenced on bone metastases in advanced treatment-naïve lung cancer.

Abstract

e21668 Background: RB1 is one of the most vital cancer suppressor genes in various cancer types. RB1 mutation always occurs in treatment-naïve small cell lung cancer (SCLC) patients or in resistance to EGFR TKI therapy of non-small cell lung cancer (NSCLC) patients. However, we observed a group of clinical NSCLC patients, and found that RB1 mutations also occurred in treatment-naïve patients. Methods: RB1 is one of the most vital cancer suppressor genes in various cancer types. RB1 mutation always occurs in treatment-naïve small cell lung cancer (SCLC) patients or in resistance to EGFR TKI therapy of non-small cell lung cancer (NSCLC) patients. However, we observed a group of clinical NSCLC patients, and found that RB1 mutations also occurred in treatment-naïve patients. Results: Nonsense and frame-shift mutations were the major pathogenic mutations found in RB1 gene, which predicted RB1 protein-deficient in these mutational patients. Furthermore, we found these RB1 mutation patients had TP53 mutations at the same time. Patients with RB1 mutation had a higher smoking prevalence than patients who had wildtype RB1 genes (P < 0.0001). Gene testing showed RB1 mutations patients also developed EGFR driver mutations, while the mutation frequency was significantly lower than RB1 wildtype patients ( P = 0.0368). Eight RB1 mutated patients diagnosed with actionable EGFR mutations, including exon 19 del, L858R, L861Q, G719S and S768I, while no patients diagnosed with EGFR exon 20 insertion. 10 (62.5%, 10/16) patients in RB1 mutated group, and 25(32.1%, 25/78) patients with RB1 wildtype had bone metastases. The proportion of bone metastases in patients with RB1 mutation was significantly increased than others ( P = 0.0216). Conclusions: This study demonstrates that the function of tumor suppressor gene RB1 in advanced stage of NSCLC. From the results, we considered RB1 mutation had influence on bone metastases. Although loss-of-function mutations in tumor suppressor gene (TSG) RB1 always had no targets therapeutic drugs, it also suggested that some other clinically treatment can be performed as soon as possible.