Inhibition of glycolysis enhances the efficacy of immunotherapy via PDK-mediated upregulation of PD-L1.

BACKGROUND: Immunotherapy for gastric cancer remains a challenge due to its limited efficacy. Metabolic reprogramming toward glycolysis has emerged as a promising avenue for enhancing the sensitivity of tumors to immunotherapy. Pyruvate dehydrogenase kinases (PDKs) play pivotal roles in regulating glycolysis. The importance of PDKs in the context of gastric cancer immunotherapy and their potential as therapeutic targets have not been fully explored. METHODS: PDK and PD-L1 expression was analyzed using data from the GSE66229 and The Cancer Genome Atlas (TCGA) cohorts. Additionally, the Immune Checkpoint Blockade Therapy Atlas (ICBatlas) database was utilized to assess PDK expression in an immune checkpoint blockade (ICB) therapy group. Subsequently, the upregulation of PD-L1 and the enhancement of anticancer effects achieved by targeting PDK were validated through in vivo and in vitro assays. The impact of PDK on histone acetylation was investigated using ChIP‒qPCR to detect changes in histone acetylation levels. RESULTS: Our analysis revealed a notable negative correlation between PD-L1 and PDK expression. Downregulation of PDK led to a significant increase in PD-L1 expression. PDK inhibition increased histone acetylation levels by promoting acetyl-CoA generation. The augmentation of acetyl-CoA production and concurrent inhibition of histone deacetylation were found to upregulate PD-L1 expression in gastric cancer cells. Additionally, we observed a significant increase in the anticancer effect of PD-L1 antibodies following treatment with a PDK inhibitor. CONCLUSIONS: Downregulation of PDK in gastric cancer cells leads to an increase in PD-L1 expression levels, thus potentially improving the efficacy of PD-L1 immune checkpoint blockade therapy.

Laparoscopic versus open gastrectomy for locally advanced gastric cancer after neoadjuvant chemotherapy: a comprehensive contrastive analysis with propensity score matching.

BACKGROUND: Laparoscopic gastrectomy (LG) is increasingly applied in locally advanced gastric cancer (LAGC) after neoadjuvant chemotherapy (NC). However, there is no study to comprehensively evaluate the clinicopathological, prognostic, and laboratory data such as nutrition, immune, inflammation-associated indexes, and tumor markers between LG and open gastrectomy (OG) for LAGC following NC. METHODS: The clinicopathological, prognostic, and laboratory data of LAGC patients with clinical stage of cT2-4aN1-3M0 who underwent gastrectomy after NC were retrospectively collected. The effects of LG and OG were compared after propensity score matching (PSM). RESULTS: This study enrolled 148 cases, of which 110 cases were included after PSM. The LG group had a shorter length of incision (P < 0.001) and was superior to OG group in terms of blood loss (P < 0.001), postoperative first flatus time (P < 0.001), and postoperative first liquid diet time (P = 0.004). No significant difference was found in postoperative complications (P = 0.482). Laboratory results showed that LG group had less reduced red blood cells (P = 0.039), hemoglobin (P = 0.018), prealbumin (P = 0.010) in 3 days after surgery, and less reduced albumin in 1 day (P = 0.029), 3 days (P = 0.015), and 7 days (P = 0.035) after surgery than the OG group. The systemic immune-inflammation index and systemic inflammatory response index were not significantly different between the two groups. As for oncological outcomes, there were no significant differences in postoperative tumor markers of CEA (P = 0.791), CA199 (P = 0.499), and CA724 (P = 0.378). The 5-year relapse-free survival rates (P = 0.446) were 46.9% and 43.3% in the LG and OG groups, with the 5-year overall survival rates (P = 0.742) being 46.7% and 52.1%, respectively; the differences were not statistically significant. Multivariate Cox regression analysis revealed that tumor size ≥ 4 cm (P = 0.021) and the absence of postoperative adjuvant chemotherapy (P = 0.012) were independent risk factors for overall survival. CONCLUSIONS: LG has faster gastrointestinal recovery, better postoperative nutritional status, and comparable oncological outcomes than OG, which can serve as an alternative surgical method for LAGC patients after NC.

Lymph node ratio is a prospective prognostic indicator for locally advanced gastric cancer patients after neoadjuvant chemotherapy.

BACKGROUND: The accuracy of lymph node ratio (LNR) as a prognostic index remains to be proven for gastric cancer patients after neoadjuvant chemotherapy (NACT). This study sought to investigate the prognostic value of LNR in locally advanced gastric cancer (LAGC) patients after NACT. METHODS: LAGC patients with clinical TNM stages 2-3, Her2(-), and Eastern Cooperative Oncology Group, scores 0-2 are routinely scheduled with NACT. Patients with LAGC after NACT and surgical operation between January 2012 and October 2020 were retrospectively reviewed. The correlation between LNR and survival was investigated. RESULTS: Overall, 148 patients were enrolled: 103 with low-LNR (LNR ≤ 30%) and 45 with high-LNR (LNR > 30%). Approximately, 50.5% and 24.4% patients responded to NACT at the primary site in the low-LNR and high-LNR groups, respectively. The overall survival (OS) and progression-free survival (PFS) of low-LNR group were considerably better than those of high-LNR group (3-year OS: 81.9% vs 18.5%, P < 0.001; 3-year PFS: 72.6% vs 13.5%, P < 0.001). In the low-LNR group, OS and PFS were superior in patients with tumor regression grade (TRG) 0-2 than in those with TRG 3 (3-year OS: 89.2% vs 73.2%, P = 0.086; 3-year PFS: 80.3% vs 66.5%, P = 0.036). In association with OS and PFS, the degree of tumor differentiation, TRG, and LNR were identified as predictive factors, and LNR was identified as the independent prognostic factor in univariate and multivariate analyses, respectively. CONCLUSIONS: LNR is a prospective index of prognosis in patients with LAGC after NACT.