Breast cancer is the second leading cause of cancer-related mortality in women, mainly due to metastasis, which is strongly associated with cancer stemness. Our previous studies showed that the eradication of cancer stem-like cells (CSCs) may be related to the activation of dopamine D1 receptor (D1DR). This study aimed to explicitly demonstrate the target-role of D1DR activation in antimetastatic therapy and to investigate the potential efficacy and the underlying D1DR-related mechanisms of QAP14, a new oral compound. 4T1, MDA-MB-231, and D1DR-knockout 4T1 (4T1-D1DR) cells were selected for in vitro study, while 4T1 and 4T1-D1DR cells were further used to establish a mouse allograft model for in vivo study. Our results showed that D1DR is abundantly expressed in both 4T1 and MDA-MB-231 cells and that knocking out D1DR in 4T1 cells accelerated migration and invasion in vitro as well as lung metastasis in vivo. QAP14 inhibited colony formation, cell motility, mammosphere formation and CSC frequency, induced CSC apoptosis and D1DR expression, and increased cAMP/cGMP levels. Additionally, QAP14 showed inhibitory effects on tumor growth and lung metastasis with acceptable safety in vivo. Knocking out D1DR almost completely abolished the efficacy, confirming that QAP14 exhibits its anti-CSC and antimetastatic effects through D1DR activation. The underlying mechanisms involved suppression of the nuclear factor κB (NF-κB)/protein kinase B (Akt) pathway and consequent downregulation of both epithelial-to-mesenchymal transition (EMT) process and cancer stemness. In summary, our findings suggest a potential candidate compound, QAP14, as well as a potential target, D1DR, for metastatic breast cancer therapy.

Immune checkpoint inhibitors (ICIs) have become a vital part of the therapeutic landscape for non-small cell lung cancer (NSCLC) in recent years benefiting from their remarkable efficacy. However, ICIs are associated with potentially lifethreatening immune-related adverse events (irAEs). This study aims to quantify dose dependence and additional influencing factors of both any grade and grade greater than or equal to 3 irAEs in patients with NSCLC treated by ICIs. The triallevel irAE data was collected and pooled from 129 cohorts in 81 clinical studies.A logit-transformed meta-regression model was applied to derive the quantitative relationship of irAE rate and ICI exposure. Programmed cell death-1 (PD-1) or programmed cell death ligand-1 (PD-L1) inhibitors showed no dose dependence in patients with NSCLC, whereas cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitors exhibited a statistically significant dose dependence when used alone or combined with PD-1 or PD-L1 inhibitors. Besides, therapy line and combination of ICIs with chemotherapy or target therapy were significant covariates. Hopefully, the results of this study can improve clinicians' awareness of irAEs and be helpful for clinical decisions during ICI treatment for NSCLC. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?Conventional clinical trials and meta-analysis have pooled and compared the incidence of immune-related adverse events (irAEs) induced by diverse immune checkpoint inhibitors (ICIs) in several cancer types. WHAT QUESTION DID THIS STUDY ADDRESS?A latest comprehensive model-based meta-analysis based on multiple types of clinical studies was conducted to quantify dose dependence and additional influencing factors of both any grade and grade greater than or equal to 3 irAEs during ICI treatment for non-small cell lung cancer (NSCLC) up to April 30, 2021.

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