The efficacy and side effects of rigosertib combined with chemotherapy in KRAS mutant colorectal cancer mice / 中华肿瘤杂志

Objective: To investigate the effect of rigosertib (RGS) combined with classic chemotherapy drugs including 5-fluorouracil, oxaliplatin, and irinotecan in colorectal cancer. Methods: Explore the synergy effects of RGS and 5-fluorouracil (5-FU), oxaliplatin (OXA), and irinotecan (IRI) on colorectal cancer by subcutaneously transplanted tumor models of mice. The mice were randomly divided into control group, RGS group, 5-FU group, OXA group, IRI group, 5-FU+ RGS group, OXA+ RGS group and IRI+ RGS group. The synergy effects of RGS and OXA on KRAS mutant colorectal cancer cell lines in vitro was detected by CCK-8. Ki-67 immunohistochemistry and TdT-mediated dUTP nick-end labeling (TUNEL) staining were performed on the mouse tumor tissue sections, and the extracted tumor tissue was analyzed by western blot. The blood samples of mice after chemotherapy and RGS treatment were collected, blood routine and liver and kidney function analysis were conducted, and H&E staining on liver sections was performed to observe the side effects of chemotherapy and RGS. Results: The subcutaneously transplanted tumor models were established successfully in all groups. 55 days after administration, the fold change of tumor size of OXA+ RGS group was 37.019±8.634, which is significantly smaller than 77.571±15.387 of RGS group (P=0.029) and 92.500±13.279 of OXA group (P=0.008). Immunohistochemical staining showed that the Ki-67 index of tumor tissue in control group, OXA group, RGS group and OXA+ RGS group were (100.0±16.8)%, (35.6±11.3)%, (54.5±18.1)% and (15.4±3.9)%, respectively. The Ki-67 index of OXA+ RGS group was significantly lower than that in control group (P=0.014), but there was no significant difference compared to OXA group and RGS group (OXA: P=0.549; RGS: P=0.218). TUNEL fluorescence staining showed that the apoptotic level of OXA+ RGS group was 3.878±0.547, which was significantly higher than 1.515±0.442 of OXA group (P=0.005) and 1.966±0.261 of RGS group (P=0.008). Western blot showed that the expressions of apoptosis related proteins such as cleaved-PARP, cleaved-caspase 3 and cleaved-caspase 8 in the tumor tissues of mice in the OXA+ RGS group were higher than those in control group, OXA group and RGS group. After the mice received RGS combined with chemotherapy drugs, there was no significant effect on liver and kidney function indexes, but the combined use of oxaliplatin and RGS significantly reduced the white blood cells [(0.385±0.215)×10(9)/L vs (5.598±0.605)×10(9)/L, P<0.001] and hemoglobin[(56.000±24.000)g/L vs (153.333±2.231)g/L, P=0.001] of the mice. RGS, chemotherapy combined with RGS and chemotherapy alone did not significantly increase the damage to liver cells. Conclusions: The combination of RGS and oxaliplatin has a stronger anti-tumor effect on KRAS mutant colorectal cancer. RGS single agent will not cause significant bone marrow suppression and hepatorenal injury in mice, but its side effects may increase correspondingly after combined with chemotherapy.

Current status and outlook of medical treatment for KRAS-mutated non-small cell lung cancer / 中华肿瘤杂志

Lung cancer remains the leading cause of cancer-related deaths in men and women worldwide, and 85% of these patients have non-small cell lung cancer. In recent years, the clinical use of targeted drug therapy and immune checkpoint inhibitors has dramatically changed the treatment landscape for advanced NSCLC. The mechanism and the value of targeted therapies have been a hot topic of research, as KRAS is one of the earliest discovered and most frequently mutated oncogenes, which is activated by binding to GTP and triggers a series of cascade reactions in cell proliferation and mitosis. The KRAS protein acts as a molecular switch and is activated by binding to GTP, triggering a series of cascade responses in cell proliferation and mitosis. Clinically, patients with KRAS mutated NSCLC have poor response to systemic medical therapy and poor prognosis. Since the first report of KRAS gene in 1982, research on KRAS targeted therapeutics has been slow, and previous studies such as farnesyltransferase inhibitors and downstream protein inhibitors of KRAS signaling pathway have not achieved the expected results, making KRAS long defined as a "non-druggable target". The deeper understanding of the crystal structure of KRAS has led to the discovery of potential therapeutic sites for KRAS and the development of several drugs directly targeting KRAS, especially KRAS G12C inhibitors such as AMG510 (sotorasib) and MRTX849 (adagrasib), which have shown encouraging results in clinical trials. In recent years, studies on the therapeutic efficacy of immune checkpoint inhibitors for KRAS-mutated NSCLC have made some progress. In this review, we systematically introduce the basic understanding of RAS gene and clinical characteristics of KRAS mutated NSCLC patients, summarize the medical treatments for KRAS mutated NSCLC, including chemotherapy, anti-vascular drug therapy and tumor immunotherapy, and focus on the review and outlook of the research progress of KRAS targeted therapy.