Microglial Priming in Bilirubin-Induced Neurotoxicity

Neuroinflammation is a major contributor to bilirubin-induced neurotoxicity, which results in severe neurological deficits. Microglia are the primary immune cells in the brain, with M1 microglia promoting inflammatory injury and M2 microglia inhibiting neuroinflammation. Controlling microglial inflammation could be a promising therapeutic strategy for reducing bilirubin-induced neurotoxicity. Primary microglial cultures were prepared from 1-3-day-old rats. In the early stages of bilirubin treatment, pro-/anti-inflammatory (M1/M2) microglia mixed polarization was observed. In the late stages, bilirubin persistence induced dominant proinflammatory microglia, forming an inflammatory microenvironment and inducing iNOS expression as well as the release of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. Simultaneously, nuclear factor-kappa B (NF-κB) was activated and translocated into the nucleus, upregulating inflammatory target genes. As well known, neuroinflammation can have an effect on N-methyl-D-aspartate receptor (NMDAR) expression or function, which is linked to cognition. Treatment with bilirubin-treated microglia-conditioned medium did affect the expression of IL-1β, NMDA receptor subunit 2A (NR2A), and NMDA receptor subunit 2B (NR2B) in neurons. However, VX-765 effectively reduces the levels of proinflammatory cytokines TNF-α, IL-6, and IL-1β, as well as the expressions of CD86, and increases the expressions of anti-inflammatory related Arg-1. A timely reduction in proinflammatory microglia could protect against bilirubin-induced neurotoxicity.

VX-765 inhibits pyroptosis and reduces inflammation to prevent acute liver failure by upregulating PPARα expression

INTRODUCTION AND OBJECTIVES

As a fatal clinical syndrome, acute liver failure (ALF) is characterized by overwhelming liver inflammation and hepatic cell death. Finding new therapeutic methods has been a challenge in ALF research. VX-765 is a known pyroptosis inhibitor and has been reported to prevent damage in a variety of diseases by reducing inflammation. However, the role of VX-765 in ALF is still unclear.

MATERIALS AND METHODS

ALF model mice were treated with D-galactosamine (D-GalN) and lipopolysaccharide (LPS). LO2 cells were stimulated with LPS. Thirty subjects were enrolled in clinical experiments. The levels of inflammatory cytokines, pyroptosis-associated proteins and peroxisome proliferator-activated receptor α (PPARα) were detected using quantitative reverse transcription-polymerase chain reaction (qRT‒PCR), western blotting and immunohistochemistry. An automatic biochemical analyzer was used to determine the serum aminotransferase enzyme levels. Hematoxylin and eosin (HE) staining was used to observe the pathological features of the liver.

RESULTS

With the progression of ALF, the expression levels of interleukin (IL) -1β, IL-18, caspase-1, and serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased. VX-765 could reduce the mortality rate of ALF mice, relieve liver pathological damage, and reduce inflammatory responses to protect against ALF. Further experiments showed that VX-765 could protect against ALF through PPARα, and this protective effect against ALF was reduced in the context of PPARα inhibition.

CONCLUSIONS

As ALF progresses, inflammatory responses and pyroptosis deteriorate gradually. VX-765 can inhibit pyroptosis and reduce inflammatory responses to protect against ALF by upregulating PPARα expression, thus providing a possible therapeutic strategy for ALF.

VX-765 has a Protective Effect on Mice with Ovarian Injury Caused by Chemotherapy

BACKGROUND

Malignant tumors continue to remain a main global public health issue. In the past 40 years, due to strides made in multi-disciplinary comprehensive treatment schemes for patients suffering from malignant tumors, especially chemotherapy schemes, the survival rate has been greatly improved in such patients. This group can be expected to maintain their fertility or have restored endocrine function following successful malignant tumor treatment. Therefore, focusing on the ovarian damage caused by chemotherapy in women of childbearing age is vital in order to protect their fertility and improve their quality of life.

OBJECTIVE

This study attempted to evaluate whether VX-765 possesses an ovarian protective effect in ovarian injury induced by chemotherapy in the mice model.

METHODS

Female C57BL/6J mice were administered with VX-765 gavage once a day for 21 consecutive days. Use of cyclophosphamide (Cy) began one week after the last gavage administration of VX- 765. Detailed classification of follicles at various levels was then quantified in each group. Immunohistochemistry and Western blot analysis were then used in order to analyze the expression of key proteins (FOXO3a, mTOR, RPS6 and AKT) as well as their phosphorylation of the PI3K / PTEN / AKT pathways in the ovary. The concentrations of AMH were measured by ELISA.

RESULTS

The follicles at all levels of Cy treated mice were less than those of the normal group (P < 0.05). Meanwhile, mice treated with VX-765 prior to receiving Cy treatment had more primordial follicles (PMF) than mice treated with Cy alone (P < 0.05). In early growing follicles (EGF) and antral follicles (AF), no difference was observed among the experimental groups (P > 0.05), however, they were lower than those in the normal group (P < 0.05). In mice treated with continuous Cy, the total follicle number (TF) of mice combined with VX-765 (C-Cy-Vx765) was higher than that of mice without VX-765, and the TF of the two groups was lower than that of the normal group (P < 0.05). The value of PMF/TF in C-Cy-Vx765 group was significantly higher than that in the other three groups, while that of EGF/TF was significantly lower (P < 0.05). Immunohistochemical results showed that the phosphorylated forms of the main proteins of the PI3K / PTEN / AKT pathway were found to be more positive in Cy treated mice. The Western blot analysis showed that when Cy and VX-765 were cotreated, the increased levels of these phosphorylated proteins decreased compared with those treated with Cy alone. The AMH level of infancy Cy and VX-765 co-treated mice was higher than that of infancy normal mice (P < 0.05). After the mice grew to sexual maturity, the AMH level of Cy and VX- 765 co-treated mice was still higher than that of Cy treated mice (P < 0.05), and there was no significant difference with normal mice (P > 0.05).

CONCLUSION

VX-765 can maintain the level of AMH and inhibit the recruitment of PMF, thus protecting mice from Cy induced gonadotropic toxicity. Accordingly, VX-765 may play a protective role in mice with ovarian injury caused by chemotherapy.

VX-765 attenuates silica-induced lung inflammatory injury and fibrosis by modulating alveolar macrophages pyroptosis in mice

Silicosis is a diffuse fibrotic lung disease in which excessive inflammatory responses are triggered by silica exposure. Pyroptosis, a pro-inflammatory mode of programmed cell death, is mediated by gasdermin and may play a pivotal role in the development of silicosis. The caspase-1 inhibitor, VX-765, was used in vivo and in vitro to investigate the effects of silica-induced early inflammatory injury and later lung fibrosis. Our findings show that VX-765 reduces inflammatory lung injury by inhibiting silica-induced pyroptosis of alveolar macrophages in a silicosis mouse model. VX-765 limits the infiltration of inflammatory M1 alveolar macrophages, decreasing expression of inflammatory cytokines, including IL-1β, TNF-α, IL-6, CCL2, and CCL3, and down-regulating endogenous DAMPs and inflammatory immune-related cell pattern recognition receptors TLR4 and NLRP3. Furthermore, VX-765 alleviates fibrosis by down-regulating α-smooth muscle actin (α-SMA), collagen, and fibronectin. In this study, we illustrate that Alveolar macrophages pyroptosis occur in the early stages of silicosis, and VX-765 can alleviate the development of silicosis by inhibiting the pyroptosis signaling pathway. These results may provide new insight into the prevention and treatment of early-stage silicosis.

VX-765 Alleviates β-Amyloid Deposition and Secondary Degeneration in the Ipsilateral Hippocampus and Ameliorates Cognitive Decline after Focal Cortical Infarction in Rats

Focal cortical infarction leads to secondary degeneration of the ipsilateral hippocampus, which is associated with poststroke cognitive impairment. VX-765 is a potent small-molecule caspase-1 inhibitor that protects against central nervous system diseases. The present study aimed to determine the protective effects of VX-765 on β-amyloid (Aβ) deposition and secondary degeneration in the hippocampus as well as cognitive decline after cortical infarction. Sprague-Dawley rats were used to establish a distal middle cerebral artery occlusion (dMCAO) model and randomly divided into the vehicle and VX-765 groups. Rats in the vehicle and VX-765 groups, respectively, were subcutaneously injected with VX-765 (50 mg/kg/d) and an isopycnic vehicle once a day for 28 days, starting 1 h after dMCAO. At the end of this 28-day period, cognitive impairment was evaluated with the Morris water maze, and secondary hippocampal damage was evaluated with Nissl staining and immunostaining methods. Neuronal damage and pyroptosis were detected by TUNEL and immunoblotting. The results revealed that VX-765 treatment ameliorated poststroke cognitive dysfunction after ischemia. VX-765 reduced Aβ deposition, neuronal loss, and glial activation compared with the vehicle control. In addition, VX-765 treatment increased BDNF levels and normalized synaptophysin protein levels in the hippocampus after cortical infarction. Notably, VX-765 treatment significantly reduced the expression of the pyroptosis-related molecules caspase-1, NLRP3, apoptosis-associated speck-like protein (ASC), gasdermin D, IL-1β, and IL-18. Additionally, VX-765 significantly decreased the numbers of TUNEL-positive cells and the levels of Bax and cleaved caspase-3 (cC3) and enhanced the levels of Bcl-2 and Bcl-xl after ischemia. Inflammatory pathways, such as the NF-κB and mitogen-activated protein kinase (MAPK) pathways, were inhibited by VX-765 treatment after ischemia. These findings revealed that VX-765 reduced Aβ deposition, pyroptosis, and apoptosis in the ipsilateral hippocampus, which may be associated with reduced secondary degeneration and cognitive decline following focal cortical infarction.

VX-765 prevents intestinal ischemia-reperfusion injury by inhibiting NLRP3 inflammasome

BACKGROUND

Intestinal ischemia-reperfusion injury (IIRI) is a common clinical event that can cause serious consequences. The study aimed to investigated the effect of VX-765 in IIRI and its mechanism.

METHODS

The hypoxia-reoxygenation (H/R) cell model and IIRI mouse model were generated to examine the in vitro and in vivo effects of VX-765 on IIRI. IIRI was evaluated by histological assessment. ELISA was performed to determine the levels of IL-6, TNF-α, IL-1β, caspase-1, and GSDMD in intestinal tissues as well as the levels of MDA, SOD, CAT, caspase-1, and GSDMD in Caco-2 cells. Relative protein levels of NLRP3, ASC, IL-18, IL-1β, cleaved Caspase1, and GSDMD-N were analyzed by Western blotting. CCK-8 Assay was conducted to determine the optimal concentration of VX-765 for the in vitro studies. Flow cytometry, fluorescence microscopy and real-time PCR (RT-PCR) were used to assess ROS levels and the mRNA levels of IL-18 and IL-1β, respectively. Immunofluorescence staining was performed to examine the subcellular localization of P65 and NLRP3.

RESULTS

VX-765 reduced IIRI-induced oxidative stress and inflammatory response both in vivo and in vitro, while it decreased the levels of TNF-α, IL-6, IL-1β as well as the modified Park/Chiu scores. The optimal concentration of VX-765 for the in vitro studies was 10 μM. Moreover, VX-765 inhibited the nuclear translocation of P65, reduced oxidative stress and down-regulated the activation of NLRP3 inflammasome.

CONCLUSION

VX-765 prevents IIRI presumably by inhibiting the activation of NLRP3 inflammasome.

Inhibition of caspase-1 ameliorates tauopathy and rescues cognitive impairment in SAMP8 mice

The inflammasome assembles leading to increased cleavage and activity of caspase-1 and downstream IL-1β release, which plays a significant role in the pathogenesis of Alzheimer's disease (AD). Previous studies have shown that caspase-1-mediated neuroinflammation occurs early in AD process. However, the detailed role of caspase-1 in aging-related AD-like neuropathology is still unclear so far. In this study, by using SAMP8 mice, an animal model of accelerated aging, we detected the levels of caspase-1 in brains of 3-, 7-, and 11-month-old mice and observed that caspase-1 was activated during aging process. More importantly, we provided the evidence that VX-765, a selective inhibitor of caspase-1, significantly rescued spatial learning and memory impairments and reduced tau hyperphosphorylation in brains of SAMP8 mice at early stages of the disease. This amelioration might be attributed to IL-1β-induced hypoactivation of tau kinases. Our results imply that caspase-1 may represent as a potential therapeutic target for neurodegenerative tauopathies.

VX-765 ameliorates renal injury and fibrosis in diabetes by regulating caspase-1-mediated pyroptosis and inflammation

INTRODUCTION

As a lytic inflammatory cell death, pyroptosis has been recently described but has not been unequivocally elucidated in diabetic nephropathy (DN). VX-765 is a safe and effective inhibitor of caspase-1, that was well tolerated in a phase II clinical trial in patients with epilepsy, but its application in DN is still undefined.

MATERIALS AND METHODS

Immunoblot, co-immunoprecipitation, confocal microscope and flow cytometry were used to analyze the effects of glucose on pyroptosis in renal tubular epithelia (HK-2). In vitro, selective caspase-1 inhibitors VX-765 and Z-YVAD-FMK were administered. Pyroptosis and fibrogenesis were determined by immunoblot, ELISA, cytotoxicity assay and flow cytometry. In vivo, diabetic mice were administered with 100 mg/kg VX-765. Renal function, pathological changes, and the expressions of NLRC4, GSDMD, IL-1β, collagen I, fibronectin and CD45 in renal cortex were evaluated.

RESULTS

We identified NLRC4 as a sensor for caspase-1 activation. Moreover, we provided morphological and molecular evidence for pyroptosis in glucose-stressed tubular cells, including ballooned cell membrane, caspase-1 immunoreactivity, GSDMD cleavage, and the release of inflammatory cytokine and cellular contents. All these effects were prevented by treatment with VX-765 or Z-YVAD-FMK, confirming that caspase-1 effectively regulates the occurrence of pyroptosis in HK-2 cells. In vivo, treatment of diabetic animals with VX-765 ameliorated renal function, suppressed inflammatory cell infiltration and pyroptosis-associated protein expression, and mitigated tubulointerstitial fibrosis.

CONCLUSIONS

This work revealed that caspase-1-mediated pyroptosis drives renal inflammation and fibrosis in diabetes. Our results are the first demonstration of VX-765 representing a promising therapeutic opportunity for alleviating the progression of DN.

VX-765 ameliorates inflammation and extracellular matrix accumulation by inhibiting the NOX1/ROS/NF-κB pathway in diabetic nephropathy

OBJECTIVE

This study explores the potential role of a highly selective caspase-1 inhibitor, VX-765, on extracellular matrix (ECM) accumulation and inflammation in diabetic nephropathy (DN) and the underlying mechanisms.

METHODS

DN rats, induced via high-fat diet/streptozotocin, were used to assess the effects of VX-765. Parallel experiments were carried out on rat mesangial cell line HBZY-1 exposed to high glucose (HG) to reveal the molecular mechanism of VX-765 in preventing DN. Survival analysis, biochemical parameters and renal oxidative stress of rats were observed, and Western blotting and immunofluorescence were evaluated. In vitro, Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX)1 silencing by RNA interference and quantitative real-time PCR (qPCR) assays were conducted in HBZY-1 cells exposed to HG levels.

KEY FINDINGS

In vivo, VX-765 significantly reduced the increase in urine albumin excretion and ECM accumulation. The phosphorylation of nuclear factor kappa-B (NF-κB) and the expression of pro-inflammatory cytokines IL-1β, IL-6 and tumor necrosis factor (TNF)-α were significantly down-regulated. Furthermore, the generation of reactive oxygen species (ROS), phosphorylation of NF-κB and the expression of the NOX1 gene or protein were significantly decreased in HBZY-1 with VX-765 (5 μM) treatment in vitro.

CONCLUSIONS

Our results demonstrated that VX-765 exerts favourable effects on DN via the simultaneous alleviation of systemic metabolic syndrome and down-regulating the renal NOX1/ROS/NF-κB pathway, suggesting that it has therapeutic potential for DN.

Depression of Pyroptosis by Inhibiting Caspase-1 Activation Improves Neurological Outcomes of Kernicterus Model Rats

Kernicterus is a severe complication of extreme neonatal hyperbilirubinemia. Prolonged exposure to high-level unconjugated bilirubin (UCB) directly damages brain tissue. Neuroinflammation is believed to contribute to UCB-induced neurotoxicity. Pyroptosis has been as a highly inflammatory form of programmed cell death. Therefore, this study aimed to explore whether pyroptosis was involved in the pathogenesis of UCB neurotoxicity in kernicterus model rats. VX-765, a specific inhibitor of caspase-1, was intraperitoneally administered to the model rats to observe its effects on the short-term and long-term outcomes of the model animals at the molecular, cellular, morphological, and behavioral levels. The results indicated that UCB significantly induced the activation of caspase-1 and gasdermin D(GSDMD), and VX-765 inhibited caspase-1-GSDMD pathway. Compared with those of the UCB group and the vehicle+UCB group, VX-765-treated rats released lower levels of IL-1β and IL-18. Furthermore, H&E and TUNEL staining showed that nerve cells in the VX-765-treated group were better preserved and had less DNA fragmentation. Most importantly, VX-765 improved both the short-term and long-term neurological functions of kernicterus model rats. This study demonstrated that pyroptosis was involved in the pathogenesis of kernicterus through caspase-1 activation, which could be inhibited by VX-765, exerting a neuroprotective effect in kernicterus model rats.

Intranasal anti-caspase-1 therapy preserves myelin and glucose metabolism in a model of progressive multiple sclerosis

Inflammatory demyelination and axonal injury in the central nervous system (CNS) are cardinal features of progressive multiple sclerosis (MS), and linked to activated brain macrophage-like cells (BMCs) including resident microglia and trafficking macrophages. Caspase-1 is a pivotal mediator of inflammation and cell death in the CNS. We investigated the effects of caspase-1 activation and its regulation in models of MS. Brains from progressive MS and non-MS patients, as well as cultured human oligodendrocytes were examined by transcriptomic and morphological methods. Next generation transcriptional sequencing of progressive MS compared to non-MS patients' normal appearing white matter (NAWM) showed induction of caspase-1 as well as other inflammasome-associated genes with concurrent suppression of neuron-specific genes. Oligodendrocytes exposed to TNFα exhibited upregulation of caspase-1 with myelin gene suppression in a cell differentiation state-dependent manner. Brains from cuprizone-exposed mice treated by intranasal delivery of the caspase-1 inhibitor, VX-765 or its vehicle, were investigated in morphological and molecular studies, as well as by fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging. Cuprizone exposure resulted in BMC and caspase-1 activation accompanied by demyelination and axonal injury, which was abrogated by intranasal VX-765 treatment. FDG-PET imaging revealed suppressed glucose metabolism in the thalamus, hippocampus and cortex of cuprizone-exposed mice that was restored with VX-765 treatment. These studies highlight the caspase-1 dependent interactions between inflammation, demyelination, and glucose metabolism in progressive MS and associated models. Intranasal delivery of an anti-caspase-1 therapy represents a promising therapeutic approach for progressive MS and other neuro-inflammatory diseases.

VX-765 enhances autophagy of human umbilical cord mesenchymal stem cells against stroke-induced apoptosis and inflammatory responses via AMPK/mTOR signaling pathway

INTRODUCTION

To investigate the protective effect of VX-765 on human umbilical mesenchymal stem cells (HUMSCs) in stroke and its mechanism.

MATERIALS AND METHODS

Mouse models of ischemic stroke were established using the distal middle cerebral artery occlusion (dMCAO) method. The dMCAO mice were accordingly transplanted with HUMSCs, VX-765-treated HUMSCs, or VX-765 + MHY185-treated HUMSCs. The HUMSCs were inserted with green fluorescent protein (GFP) for measurement of transplantation efficiency which was determined by immunofluorescence assay. Oxygen-glucose deprivation (OGD) was applied to mimic ischemic environment in vitro experiments, and the HUMSCs herein were transfected with AMPK inhibitor Compound C or autophagy inhibitor 3-MA. MTT assay was used to test the toxicity of VX-765. TUNEL staining and ELISA were applied to measure the levels of apoptosis and inflammatory cytokines (IL-1β, IL-6, and IL-10), respectively. The expressions of autophagy-associated proteins, AMPK, and mTOR were detected by Western blotting. TTC staining was applied to reveal the infarct lesions in the brain of dMCAO mice.

RESULTS

The pro-inflammatory cytokines, TUNEL-positive cells, and p-mTOR were decreased while the anti-inflammatory cytokine, autophagy-related proteins, and p-AMPK were increased in HUMSCs treated with VX-765 under OGD condition. Different expression patterns were found with the above factors after transfection of 3-MA or Compound C. The pro-inflammatory cytokines, TUNEL-positive cells, and infarct sections were decreased while the anti-inflammatory cytokine and autophagy-related proteins were increased in dMCAO mice transplanted with VX-765-treated HUMSCs compared to those transplanted with HUMSCs only. The autophagy was inhibited while p-mTOR was up-regulated after transfection of MHY.

CONCLUSION

VX-765 protects HUMSCs against stroke-induced apoptosis and inflammatory responses by activating autophagy via the AMPK/mTOR signaling pathway in vivo and in vitro.

Caspase-1 inhibition by VX-765 administered at reperfusion in P2Y12 receptor antagonist-treated rats provides long-term reduction in myocardial infarct size and preservation of ventricular function

Patients with acute myocardial infarction receive a P2Y₁₂ receptor antagonist prior to reperfusion, a treatment that has reduced, but not eliminated, mortality, or heart failure. We tested whether the caspase-1 inhibitor VX-765 given at reperfusion (a requirement for clinical use) can provide sustained reduction of infarction and long-term preservation of ventricular function in a pre-clinical model of ischemia/reperfusion that had been treated with a P2Y₁₂ receptor antagonist. To address, the hypothesis open-chest rats were subjected to 60-min left coronary artery branch occlusion/120-min reperfusion. Vehicle or inhibitors were administered intravenously immediately before reperfusion. With vehicle only, 60.3 ± 3.8% of the risk zone suffered infarction. Ticagrelor, a P2Y₁₂ antagonist, and VX-765 decreased infarct size to 42.8 ± 3.3 and 29.2 ± 4.9%, respectively. Combining ticagrelor with VX-765 further decreased infarction to 17.5 ± 2.3%. Similar to recent clinical trials, combining ticagrelor and ischemic postconditioning did not result in additional cardioprotection. VX-765 plus another P2Y₁₂ antagonist, cangrelor, also decreased infarction and preserved ventricular function when reperfusion was increased to 3 days. In addition, VX-765 reduced infarction in blood-free, isolated rat hearts indicating at least a portion of injurious caspase-1 activation originates in cardiac tissue. While the pro-drug VX-765 only protected isolated hearts when started prior to ischemia, its active derivative VRT-043198 provided the same amount of protection when started at reperfusion, indicating that even in blood-free hearts, caspase-1 appears to exert its injury only at reperfusion. Moreover, VX-765 decreased circulating IL-1β, prevented loss of cardiac glycolytic enzymes, preserved mitochondrial complex I activity, and decreased release of lactate dehydrogenase, a marker of pyroptosis. Our results are the first demonstration of a clinical-grade drug given at reperfusion providing additional, sustained infarct size reduction when added to a P2Y₁₂ receptor antagonist.

Preclinical Screening for Treatments for Infantile Spasms in the Multiple Hit Rat Model of Infantile Spasms: An Update

Infantile spasms are the typical seizures of West syndrome, an infantile epileptic encephalopathy with poor outcomes. There is an increasing need to identify more effective and better tolerated treatments for infantile spasms. We have optimized the rat model of infantile spasms due to structural etiology, the multiple-hit rat model, for therapy discovery. Here, we test three compounds administered after spasms induction in the multiple hit model for efficacy and tolerability. Specifically, postnatal day 3 (PN3) male Sprague-Dawley rats were induced by right intracerebral injections of doxorubicin and lipopolysaccharide. On PN5 p-chlorophenylalanine was given intraperitoneally (i.p.). Daily monitoring of weights and developmental milestones was done and rats were intermittently video monitored. A blinded, randomized, vehicle-controlled study design was followed. The caspase 1 inhibitor VX-765 (50-200 mg/kg i.p.) and the GABA_B receptor inhibitor CGP35348 (12.5-100 mg/kg i.p.) each was administered in different cohorts as single intraperitoneal injections on PN4, using a dose- and time-response design with intermittent monitoring till PN5. 17β-estradiol (40 ng/g/day subcutaneously) was given daily between PN3-10 and intermittent monitoring was done till PN12. None of the treatments demonstrated acute or delayed effects on spasms, yet all were well tolerated. We discuss the implications for therapy discovery and challenges of replication trials.