Quantification of pharmacokinetic profiles of PD-1/PD-L1 antibodies by validated ELISAs

Immunotherapy has changed the paradigm of cancer treatments. In this way, several combinatorial strategies based on monoclonal antibodies (mAb) such as anti (a)-PD-1 or anti (a)-PD-L1 are often reported to yield promising clinical benefits. However, the pharmacokinetic (PK) behavior of these mAbs is a critical issue that requires selective analytical techniques. Indeed, few publications report data on a-PD1/a-PD-L1 exposure and its relationship with therapeutic or toxic effects. In this regard, preclinical assays allow the time profiles of antibody plasma concentrations to be characterized rapidly and easily, which may help to increase PK knowledge. In this study, we have developed and validated two in-house ELISAs to quantify a-PD-1 and a-PD-L1 in plasma collected from tumor-bearing mice. The linear range for the a-PD-1 assay was 2.5–125 ng/mL and 0.11–3.125 ng/mL for the a-PD-L1 assay, whereas the intra-and inter-day precision was lower than 20% for both analytes. The PK characterization revealed a significant decrease in drug exposure after administration of multiple doses. Plasma half-life for a-PD-1 was slightly shorter (22.3 h) than for a-PD-L1 (46.7 h). To our knowledge, this is the first reported preclinical ELISA for these immune checkpoint inhibitors, which is sufficiently robust to be used in different preclinical models. These methods can help to understand the PK behavior of these antibodies under different scenarios and the relationship with response, thus guiding the choice of optimal doses in clinical settings

Long-Term Systemic Expression of a Novel PD-1 Blocking Nanobody from an AAV Vector Provides Antitumor Activity without Toxicity

Immune checkpoint blockade using monoclonal antibodies (mAbs) able to block programmed death-1 (PD-1)/PD-L1 axis represents a promising treatment for cancer. However, it requires repetitive systemic administration of high mAbs doses, often leading to adverse effects. We generated a novel nanobody against PD-1 (Nb11) able to block PD-1/PD-L1 interaction for both mouse and human molecules. Nb11 was cloned into an adeno-associated virus (AAV) vector downstream of four different promoters (CMV, CAG, EF1α, and SFFV) and its expression was analyzed in cells from rodent (BHK) and human origin (Huh-7). Nb11 was expressed at high levels in vitro reaching 2–20 micrograms/mL with all promoters, except SFFV, which showed lower levels. Nb11 in vivo expression was evaluated in C57BL/6 mice after intravenous administration of AAV8 vectors. Nb11 serum levels increased steadily along time, reaching 1–3 microgram/mL two months post-treatment with the vector having the CAG promoter (AAV-CAG-Nb11), without evidence of toxicity. To test the antitumor potential of this vector, mice that received AAV-CAG-Nb11, or saline as control, were challenged with colon adenocarcinoma cells (MC38). AAV-CAG-Nb11 treatment prevented tumor formation in 30% of mice, significantly increasing survival. These data suggest that continuous expression of immunomodulatory nanobodies from long-term expression vectors could have antitumor effects with low toxicity

Quantification of Pharmacokinetic Profiles of PD-1/PD-L1 Antibodies by Validated ELISAs

Immunotherapy has changed the paradigm of cancer treatments. In this way, several combinatorial strategies based on monoclonal antibodies (mAb) such as anti (a)-PD-1 or anti (a)-PD-L1 are often reported to yield promising clinical benefits. However, the pharmacokinetic (PK) behavior of these mAbs is a critical issue that requires selective analytical techniques. Indeed, few publications report data on a-PD1/a-PD-L1 exposure and its relationship with therapeutic or toxic effects. In this regard, preclinical assays allow the time profiles of antibody plasma concentrations to be characterized rapidly and easily, which may help to increase PK knowledge. In this study, we have developed and validated two in-house ELISAs to quantify a-PD-1 and a-PD-L1 in plasma collected from tumor-bearing mice. The linear range for the a-PD-1 assay was 2.5–125 ng/mL and 0.11–3.125 ng/mL for the a-PD-L1 assay, whereas the intra-and inter-day precision was lower than 20% for both analytes. The PK characterization revealed a significant decrease in drug exposure after administration of multiple doses. Plasma half-life for a-PD-1 was slightly shorter (22.3 h) than for a-PD-L1 (46.7 h). To our knowledge, this is the first reported preclinical ELISA for these immune checkpoint inhibitors

PDL1 Signals through Conserved Sequence Motifs to Overcome Interferon-Mediated Cytotoxicity

PDL1 blockade produces remarkable clinical responses, thought to occur by T cell reactivation through prevention of PDL1-PD1 T cell inhibitory interactions. Here, we find that PDL1 cell-intrinsic signaling protects cancer cells from interferon (IFN) cytotoxicity and accelerates tumor progression. PDL1 inhibited IFN signal transduction through a conserved class of sequence motifs that mediate crosstalk with IFN signaling. Abrogation of PDL1 expression or antibody-mediated PDL1 blockade strongly sensitized cancer cells to IFN cytotoxicity through a STAT3/caspase-7-dependent pathway. Moreover, somatic mutations found in human carcinomas within these PDL1 sequence motifs disrupted motif regulation, resulting in PDL1 molecules with enhanced protective activities from type I and type II IFN cytotoxicity. Overall, our results reveal a mode of action of PDL1 in cancer cells as a first line of defense against IFN cytotoxicity

Local delivery of optimized nanobodies targeting the PD-1/PD-L1 axis with a self-amplifying RNA viral vector induces potent antitumor responses

Despite the success of immune checkpoint blockade for cancer therapy, many patients do not respond adequately. We aimed to improve this therapy by optimizing both the antibodies and their delivery route, using small monodomain antibodies (nanobodies) delivered locally with a self-amplifying RNA (saRNA) vector based on Semliki Forest virus (SFV). We generated nanobodies against PD-1 and PD-L1 able to inhibit both human and mouse interactions. Incorporation of a dimerization domain reduced PD-1/PD-L1 IC50 by 8- and 40-fold for antiPD-L1 and anti-PD-1 nanobodies, respectively. SFV viral particles expressing dimeric nanobodies showed a potent antitumor response in the MC38 model, resulting in >50% complete regressions, and showed better therapeutic efficacy compared to vectors expressing conventional antibodies. These effects were also observed in the B16 melanoma model. Although a short-term expression of nanobodies was observed due to the cytopathic nature of the saRNA vector, it was enough to generate a strong proinflammatory response in tumors, increasing infiltration of NK and CD8+ T cells. Delivery of the SFV vector expressing dimeric nanobodies by local plasmid electroporation, which could be more easily translated to the clinic, also showed a potent antitumor effect

Methyl donor supplementation in rats reverses the deleterious effect of maternal separation on depression-like behaviour

Adverse early life events are associated with altered stress responsiveness and metabolic disturbances in the adult life. Dietary methyl donor supplementation could be able to reverse the negative effects of maternal separation by affecting DNA methylation in the brain. In this study, maternal separation during lactation reduced body weight gain in the female adult offspring without affecting food intake, and altered total and HDL-cholesterol levels. Also, maternal separation induced a cognitive deficit as measured by NORT and an increase in the immobility time in the Porsolt forced swimming test, consistent with increased depression-like behaviour. An 18-week dietary supplementation with methyl donors (choline, betaine, folate and vitamin B12) from postnatal day 60 also reduced body weight without affecting food intake. Some of the deleterious effects induced by maternal separation, such as the abnormal levels of total and HDL-cholesterol, but especially the depression-like behaviour as measured by the Porsolt test, were reversed by methyl donor supplementation. Also, the administration of methyl donors increased total DNA methylation (measured by immunohistochemistry) and affected the expression of insulin receptor in the hippocampus of the adult offspring. However, no changes were observed in the DNA methylation status of insulin receptor and corticotropin-releasing hormone (CRH) promoter regions in the hypothalamus. In summary, methyl donor supplementation reversed some of the deleterious effects of an early life-induced model of depression in rats and altered the DNA methylation profile in the brain

The behavioral and immunological impact of maternal separation: a matter of timing

Maternal separation (MS), an early life stressful event, has been demonstrated to trigger neuropsychiatric disorders later in life, in particular depression. Experiments using rodents subjected to MS protocols have been very informative for the establishment of this association. However, the mechanism by which MS leads to neuropsychiatric disorders is far from being understood. This is probably associated with the multifactorial nature of depression but also with the fact that different research MS protocols have been used (that vary on temporal windows and time of exposure to MS). In the present study, MS was induced in rats in two developmental periods: for 6h per day for 14 days between postnatal days 2-15 (MS2-15) and 7-20 (MS7-20). These two periods were defined to differ essentially on the almost complete (MS2-15) or partial (MS7-20) overlap with the stress hypo-responsive period. Behavioral, immunological, and endocrine parameters, frequently associated with depressive-like behavior, were analyzed in adulthood. Irrespectively from the temporal window, both MS exposure periods led to increased sera corticosterone levels. However, only MS2-15 animals displayed depressive and anxious-like behaviors. Moreover, MS2-15 was also the only group presenting alterations in the immune system, displaying decreased percentage of CD8(+) T cells, increased spleen T cell CD4/CD8 ratio, and thymocytes with increased resistance to dexamethasone-induced cell death. A linear regression model performed to predict depressive-like behavior showed that both corticosterone levels and T cell CD4/CD8 ratio explained 37% of the variance observed in depressive-like behavior. Overall, these findings highlight the existence of "critical periods" for early life stressful events to exert programing effects on both central and peripheral systems, which are of relevance for distinct patterns of susceptibility to emotional disorders later in life.We acknowledge the Portuguese Foundation for Science and Technology (FCT) for providing a fellowship to S. Roque (SFRH/BPD/72710/2010). This work was also supported by FCT grants (co-financed by COMPETE funds) PTDC/SAU-NEU/105180/2008 and PTDC/PSI-PCO/116612/2010 and co-financed by the Portuguese North Regional Operational Program (ON.2 - O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER)

Short-term local expression of a PD-L1 blocking antibody from a self-replicating RNA vector induces potent antitumor responses

Immune checkpoint blockade has shown anti-cancer efficacy, but requires systemic administration of monoclonal antibodies (mAbs), often leading to adverse effects. To avoid toxicity, mAbs could be expressed locally in tumors. We developed adeno-associated virus (AAV) and Semliki Forest virus (SFV) vectors expressing anti-programmed death ligand 1 (aPDL1) mAb. When injected intratumorally in MC38 tumors, both viral vectors led to similar local mAb expression at 24 h, diminishing quickly in SFV-aPDL1-treated tumors. However, SFV-aPDL1 induced >40% complete regressions and was superior to AAV-aPDL1, as well as to aPDL1 mAb given systemically or locally. SFV-aPDL1 induced abscopal effects and was also efficacious against B16-ovalbumin (OVA). The higher SFV-aPDL1 antitumor activity could be related to local upregulation of interferon-stimulated genes because of SFV RNA replication. This was confirmed by combining local SFV-LacZ administration and systemic aPDL1 mAb, which provided higher antitumor effects than each separated agent. SFVaPDL1 promoted tumor-specific CD8 T cells infiltration in both tumor models. In MC38, SFV-aPDL1 upregulated co-stimulatory markers (CD137/OX40) in tumor CD8 T cells, and its combination with anti-CD137 mAb showed more pronounced antitumor effects than each single agent. These results indicate that local transient expression of immunomodulatory mAbs using non-propagative RNA vectors inducing type I interferon (IFN-I) responses represents a potent and

ZEB1/miR-200c/AGR2: A New Regulatory Loop Modulating the Epithelial-Mesenchymal Transition in Lung Adenocarcinomas

Epithelial-mesenchymal transition (EMT) is a process involved not only in morphogenesis and embryonic development, but also in cancer progression, whereby tumor cells obtain a more aggressive metastatic phenotype. Anterior gradient protein 2 (AGR2) maintains the epithelial phenotype and blocks the induction of EMT, thus playing an undeniable role in tumor progression. However, the mechanism through which AGR2 expression is regulated, not only during EMT, but also in the early stages of cancer development, remains to be elucidated. In the present study, we show an inverse correlation of AGR2 with ZEB1 (zinc finger enhancer binding protein, EF1) that was verified by analysis of several independent clinical data sets of lung adenocarcinomas. We also identified the ZEB1 binding site within the AGR2 promoter region and confirmed AGR2 as a novel molecular target of ZEB1. The overexpression of ZEB1 decreased the promoter activity of the AGR2 gene, which resulted in reduced AGR2 protein level and the acquisition of a more invasive phenotype of these lung cancer cells. Conversely, silencing of ZEB1 led not only to increased levels of AGR2 protein, but also attenuated the invasiveness of tumor cells. The AGR2 knockout, vice versa, increased ZEB1 expression, indicating that the ZEB1/AGR2 regulatory axis may function in a double negative feedback loop. In conclusion, we revealed for the first time that ZEB1 regulates AGR2 at the transcriptional level, while AGR2 presence contributes to ZEB1 mRNA degradation. Thus, our data identify a new regulatory mechanism between AGR2 and ZEB1, two rivals in the EMT process, tightly associated with the development of metastasis