Efficacy and safety of KL-A167 in previously treated recurrent or metastatic nasopharyngeal carcinoma: a multicenter, single-arm, phase 2 study.

Background: KL-A167 is a fully humanized monoclonal antibody targeting programmed cell death-ligand 1. This phase 2 study aimed to evaluate the efficacy and safety of KL-A167 in Chinese patients with previously treated recurrent or metastatic (R/M) nasopharyngeal carcinoma (NPC). Methods: This was a multicentre, single-arm, phase 2 study of KL-A167 in R/M NPC (KL167-2-05-CTP) (NCT03848286), conducted at 42 hospitals across the People's Republic of China. Eligible patients had histologically confirmed non-keratinising R/M NPC, and had failed at least two lines of chemotherapy. Patients received KL-A167 900mg intravenously once every 2 weeks until confirmed disease progression, intolerable toxicity, or withdrawal of informed consent. The primary endpoint was objective response rate (ORR) assessed by the independent review committee (IRC) according to RECIST v1.1. Findings: Between Feb 26th, 2019 and Jan 13th, 2021, 153 patients were treated. Totally, 132 patients entered full analysis set (FAS) and were evaluated for the efficacy. As of data cutoff date on Jul 13th, 2021, the median follow-up time was 21.7 months (95%CI 19.8-22.5). For FAS population, the IRC-assessed ORR was 26.5% (95%CI 19.2-34.9%), and disease control rate (DCR) was 56.8% (95%CI 47.9-65.4%). Median progression-free survival (PFS) was 2.8 months (95%CI 1.5-4.1) . Median duration of response was 12.4 months (95%CI 6.8-16.5), and median overall survival (OS) was 16.2 months (95%CI 13.4-21.3). When using the cutoff of 1000 copies/ml, 5000 copies/ml and 10,000 copies/ml for plasma EBV DNA titer, baseline low plasma EBV DNA was consistently related with better DCR, PFS and OS. Dynamic change of plasma EBV DNA was significantly associated with ORR and PFS. Among 153 patients, treatment related-adverse events (TRAEs) occurred in 73.2% of patients, and grade ≥3 TRAEs were in 15.0% of patients. No TRAE leading to death was reported. Conclusion: In this study, KL-A167 showed promising efficacy and an acceptable safety profile in patients with previously treated R/M NPC. Baseline plasma EBV DNA copy number might be a potentially useful prognostic biomarker for KL-A167 treatment, and post-treatment EBV DNA decrease might be correlated with better response to KL-A167. Funding: Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd., China National Major Project for New Drug Innovation (2017ZX09304015).

MicroRNA-27a Promotes Inefficient Lysosomal Clearance in the Hippocampi of Rats Following Chronic Brain Hypoperfusion.

Chronic brain hypoperfusion (CBH) induces the accumulation of abnormal cellular proteins, accompanied by cognitive decline, and the autophagic-lysosomal system is abnormal in dementia. Whether CBH accounts for autophagic-lysosomal neuropathology remains unknown. Here, we show that CBH significantly increased the number of autophagic vacuoles (AVs) with high LC3-II levels, but decreased SQSTM1 and cathepsin D levels in the hippocampi of rats following bilateral common carotid artery occlusion (2VO) for 2 weeks. Further studies showed that microRNA-27a (Mir27a) was upregulated at 2 weeks compared with the sham group. Additionally, LAMP-2 proteins were downregulated by Mir27a overexpression, upregulated by Mir27a inhibition, and unchanged by binding-site mutations or miR-masks, indicating that lamp-2 is the target of Mir27a. Knockdown of endogenous Mir27a prevented the reduction of LAMP-2 protein expression as well as the accumulation of AVs in the hippocampi of 2VO rats. Overexpression of Mir27a induced, while the knockdown of Mir27a reduced, the accumulation of AVs and the LC3-II level in cultured neonatal rat neurons. The results revealed that CBH in rats at 2 weeks could induce inefficient lysosomal clearance, which is regulated by the Mir27a-mediated downregulation of LAMP-2 protein expression. These findings provide an insight into a novel molecular mechanism of autophagy at the miRNA level.

Knockdown of microRNA-195 contributes to protein phosphatase-2A inactivation in rats with chronic brain hypoperfusion.

Reduction of protein phosphatase-2A (PP2A) activity is a common clinical feature of Alzheimer's disease and vascular dementia. In this study, we observed that chronic brain hypoperfusion induced by bilateral common carotid artery occlusion of rats led to PP2A inactivation based on the increase in tyrosine-307 phosphorylation and leucine-309 demethylation of PP2AC and the depression in PP2ABα. Knockdown of miR-195 using overexpression of its antisense molecule oligonucleotide (pre-AMO-miR-195) delivered by a lentivirus (lenti-pre-AMO-miR-195) increased tyrosine-307 phosphorylation and decreased both PP2ABα expression and leucine-309 methylation; these effects were prevented by the overexpression of miR-195 using lenti-pre-miR-195 and controlled by an increase in methylesterase (PME-1) and a decrease in leucine carboxyl methyltransferase-1. In vitro studies demonstrated that miR-195 regulated PME-1 expression by binding to the Ppme1 gene 3'-untranslated region (3'UTR) domain. Masking the miR-195 binding sites in the amyloid precursor protein (APP) and ß-site APP cleaving enzyme 1 genes prevented miR-195-induced leucine carboxyl methyltransferase-1 elevation. We concluded that the miR-195 downregulation in chronic brain hypoperfusion involved PP2A inactivity, which was mediated by the post-transcriptional regulation PME-1, APP, and ß-site APP cleaving enzyme 1 expression.

Activation of Cdk5/p25 and tau phosphorylation following chronic brain hypoperfusion in rats involves microRNA-195 down-regulation.

Chronic brain hypoperfusion (CBH) is a common clinical feature of Alzheimer's disease and vascular dementia, but the underlying molecular mechanism is unclear. Our previous study reported that the down-regulation of microRNA-195 (miR-195) promotes amyloidogenesis via regulation of amyloid precursor protein and ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) expression at the post-transcriptional level in CBH rats with bilateral common carotid artery occlusion (2VO). CBH owing to unilateral common carotid artery occlusion (UCCAO) increases tau phosphorylation levels at multiple phosphorylation sites in the brain, but the molecular mechanism is poorly understood. The purpose of this study was to investigate whether miR-195 could both deregulate amyloid metabolism and indirectly deregulate tau phosphorylation in CBH. We observed that 2VO leads to tau hyperphosphorylation at Ser202/Thr205, Ser262, Thr231, and Ser422 and to the conversion from cyclin-dependent kinase 5 (Cdk5)/p35 to Cdk5/p25 in rat hippocampi. Endogenous miR-195 was knocked down using over-expression of its antisense molecule (pre-AMO-miR-195) via a lentivirus (lenti-pre-AMO-miR-195); this knockdown increased the tau phosphorylation at Ser202/Thr205, Ser262, Thr231, Ser422, and the Cdk5/p25 activation, but over-expression of miR-195 using lenti-pre-miR-195 decreased the tau phosphorylation and Cdk5/p25 activation. Further in vitro studies demonstrated that miR-195 over-expression prevented tau hyperphosphorylation and Cdk5/p35 activity, which were increased by miR-195 inhibition. A dual luciferase reporter assay showed that miR-195 bound to the Cdk5r1 gene, which encodes p35 protein, in the 3'UTR and inhibited p35 expression. We concluded that tau hyperphosphorylation involves the down-regulation of miR-195, which is mediated by Cdk5/p25 activation in 2VO rats. Our findings demonstrated that down-regulation of miR-195 led to increased vulnerability via the regulation of multiple targets. Schematic diagram of miR-195 mediated Aß aggregation and tau hyperphosphorylation in chronic brain hypoperfusion (CBH). First, CBH results in the elevation of nuclear factor-κB (NF-κB), which binds with the promoter sequences of miR-195 and negatively regulates the expression of miR-195. Second, down-regulated miR-195 induces up-regulation of APP and BACE1 and leads to an increase in Aß levels. Third, some of the elevated Aß then enter the intracellular space and activate calpain, which promotes the conversion of Cdk5/p35 to Cdk5/p25 and catalyzes the degradation of IκB; IκB is an inhibitor of NF-κB, which activates NF-κB. Cdk5/p25 directly phosphorylates Tau. Fourth, down-regulated miR-195 induces an up-regulation of p35, which provides the active substrates of p25. Our findings demonstrated that the down-regulation of miR-195 plays a key role in the increased vulnerability to dementia via the regulation of multiple targets following CBH.