ABSTRACT
Background: A paucity of strategies exist for extensive-stage small cell lung cancer (ES-SCLC) patients who fail the first-line chemotherapy. Apatinib is a tyrosine kinase inhibitor (TKI) that selectively inhibits vascular endothelial growth factor receptor-2 (VEGFR-2), which has been demonstrated to have active anti-tumor activity in ES-SCLC when used only or combined with PD-1 inhibitors or chemotherapy with good tolerance. However, the efficacy and safety of apatinib monotherapy is unclear in second-line or beyond treatment of ES-SCLC. Methods: In this prospective, exploratory, single-arm, multi-center study, eligible patients were aged 18 years or older with histologically confirmed ES-SCLC, and had progressed on, or were intolerant to previous systemic treatment. Patients received apatinib 500 mg (orally qd, every 4 weeks a cycle). The efficacy was assessed after 1 cycle and then every 2 cycles based on computed tomography imaging per the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1). The primary endpoint was progression-free survival (PFS). The adverse events (AEs) were assessed per the National Cancer Institute Common Terminology Criteria for Adverse Events 4.0 (NCI-CTCAE 4.0). This study is registered in the Chinese Clinical Trial Registry, number ChiCTR-OPC-17013964. Results: From 28 July 2017 to 21 June 2019, 62 patients were screened for eligibility, among whom 57 patients were available for efficacy and safety analysis. The objective response rate (ORR) was 14.3% and disease control rate (DCR) was 79.6%. The median PFS was 5.6 months [95% confidence interval (CI): 3.3-8.0 months] and the median overall survival (OS) was 11.2 months (95% CI: 7.5-24.0 months). Among the participants who received apatinib as second-line treatment, the median PFS and OS were 6.1 months (95% CI: 2.6-7.6 months) and 12.0 months (95% CI: 7.9 months to not reached), respectively. The most common AEs of all grades were anemia (36.8%), hypertension (33.3%), fatigue (31.6%), blood bilirubin increased (22.8%), elevated transaminase (19.3%), and hand-foot syndrome (17.54%). Grade 3 AEs included 2 (3.5%) cases of hypertension and 1 (1.8%) case of fatigue. No grade 4/5 AEs were observed. Conclusions: Apatinib showed encouraging anti-tumor activity in pretreated ES-SCLC patients with tolerable toxicities. Further larger scale studies are warranted to demonstrate the efficacy of apatinib.
ABSTRACT
M2-polarized tumor-associated macrophages (TAMs) are key regulators of the link between inflammation and cancer. A negative correlation between infiltration intensity of M2-polarized TAMs and prognosis of pancreatic cancer has been reported. Epithelial-mesenchymal transition (EMT) is an important biological process in the progression of primary tumors toward metastasis. Inflammation-induced EMT has been previously shown, therefore, we hypothesized M2-polarized TAMs could induce EMT in pancreatic cancer. Toll-like receptor 4 (TLR4) signaling has an active role in tumor progression during chronic inflammation and the receptor is primarily expressed on macrophages. Activation of TLR4 on M2-polarized TAMs stimulates an increase in the cytokine interleukin-10 (IL-10); consequently, another aim was to investigate the potential role of TLR4/IL-10 signaling in the EMT of pancreatic cancer. Treatment with IL-4 (20 ng/ml) for 24 h successfully induced the polarization of macrophage cell line RAW 264.7 to M2 phenotype, IL-10(high), IL-12(low), and IL-23(low), and high expression of CD204 and CD206. A coculture system allowed investigation of the roles of M2-polarized TAMs and TLR4/IL-10 signaling in the EMT of Panc-1 and BxPC-3 pancreatic cancer cell lines. Our results showed that coculture with M2-polarized TAMs increased fibroblastic morphology, upregulated mesenchymal markers vimentin and snail at the mRNA and protein levels, and increased proliferation, migration, and metalloproteinase (MMP)2 and MMP9 proteolytic activity in pancreatic cancer cells. Simultaneously, coculture with M2-polarized TAMs decreased the expression of the epithelial marker E-cadherin. Coculture with pancreatic cancer cells increased TLR4 mRNA and protein expression in M2-polarized TAMs. Application of TLR4 siRNA and neutralizing antibodies against TLR4 and IL-10 markedly inhibited E-cadherin reduction and the upregulation of snail and vimentin. Furthermore, activation of TLR4 signaling by lipopolysaccharide profoundly increased the EMT of pancreatic cancer cells. In conclusion, M2-polarized TAMs promoted EMT in pancreatic cancer cells partially through TLR4/IL-10 signaling, suggesting novel therapeutic strategies and enhancing our understanding of M2-polarized TAMs.
