The Role and Prospects of Mesenchymal Stem Cells in Skin Repair and Regeneration.

Mesenchymal stem cells (MSCs) have been recognized as a cell therapy with the potential to promote skin healing. MSCs, with their multipotent differentiation ability, can generate various cells related to wound healing, such as dermal fibroblasts (DFs), endothelial cells, and keratinocytes. In addition, MSCs promote neovascularization, cellular regeneration, and tissue healing through mechanisms including paracrine and autocrine signaling. Due to these characteristics, MSCs have been extensively studied in the context of burn healing and chronic wound repair. Furthermore, during the investigation of MSCs, their unique roles in skin aging and scarless healing have also been discovered. In this review, we summarize the mechanisms by which MSCs promote wound healing and discuss the recent findings from preclinical and clinical studies. We also explore strategies to enhance the therapeutic effects of MSCs. Moreover, we discuss the emerging trend of combining MSCs with tissue engineering techniques, leveraging the advantages of MSCs and tissue engineering materials, such as biodegradable scaffolds and hydrogels, to enhance the skin repair capacity of MSCs. Additionally, we highlight the potential of using paracrine and autocrine characteristics of MSCs to explore cell-free therapies as a future direction in stem cell-based treatments, further demonstrating the clinical and regenerative aesthetic applications of MSCs in skin repair and regeneration.

US Food and Drug Administration Approval Summary: Elacestrant for Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative, ESR1-Mutated Advanced or Metastatic Breast Cancer.

PURPOSE: The US Food and Drug Administration (FDA) approved elacestrant for the treatment of postmenopausal women or adult men with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-), estrogen receptor 1 (ESR1)-mutated advanced or metastatic breast cancer with disease progression after at least one line of endocrine therapy (ET). PATIENTS AND METHODS: Approval was based on EMERALD (Study RAD1901-308), a randomized, open-label, active-controlled, multicenter trial in 478 patients with ER+, HER2- advanced or metastatic breast cancer, including 228 patients with ESR1 mutations. Patients were randomly assigned (1:1) to receive either elacestrant 345 mg orally once daily (n = 239) or investigator's choice of ET (n = 239). RESULTS: In the ESR1-mut subgroup, EMERALD demonstrated a statistically significant improvement in progression-free survival (PFS) by blinded independent central review assessment (n = 228; hazard ratio [HR], 0.55 [95% CI, 0.39 to 0.77]; P value = .0005). Although the overall survival (OS) end point was not met, there was no trend toward a potential OS detriment (HR, 0.90 [95% CI, 0.63 to 1.30]) in the ESR1-mut subgroup. PFS also reached statistical significance in the intention-to-treat population (ITT, N = 478; HR, 0.70 [95% CI, 0.55 to 0.88]; P value = .0018). However, improvement in PFS in the ITT population was primarily attributed to results from patients in the ESR1-mut subgroup. More patients who received elacestrant experienced nausea, vomiting, and dyslipidemia. CONCLUSION: The approval of elacestrant in ER+, HER2- advanced or metastatic breast cancer was restricted to patients with ESR1 mutations. Benefit-risk assessment in the ESR1-mut subgroup was favorable on the basis of a statistically significant improvement in PFS in the context of an acceptable safety profile including no evidence of a potential detriment in OS. By contrast, the benefit-risk assessment in patients without ESR1 mutations was not favorable. Elacestrant is the first oral estrogen receptor antagonist to receive FDA approval for patients with ESR1 mutations.

Channel-aware low Earth orbit satellite cluster networking for space-to-Earth laser communication: reliability and bandwidth advantages.

The reliability of the space-to-Earth laser communication plays a crucial role in providing uninterrupted real-time services in satellite optical networks. In traditional satellite optical networks, the space-to-Earth laser communication is carried out using a monolithic satellite in close proximity to the target optical ground station. However, the reliability of the communication in this approach is heavily influenced by the atmospheric environment. For instance, variations in cloud thickness can cause fluctuations in the link quality of the space-to-Earth laser communication, significantly reducing its reliability. This study proposes an innovative channel-adaptive space-to-Earth laser communication (CA-S2E-LC) architecture based on satellite cluster optical networking (SCON). SCON provides space-diversity link sets, reducing the probability of space-to-Earth laser communications affected by clouds. By leveraging the perception of link quality, the CA-S2E-LC architecture can adaptively choose the better space-to-Earth laser communication links established by member satellites within a satellite cluster under different environments, and properly schedule the resource, ensuring reliable space-to-Earth laser communication. The principles of the SCON is analyzed and the implementation of the CA-S2E-LC architecture is demonstrated through the explanation of hardware and functional modules, workflows, finite state machines, and strategies. Simulation results demonstrate that the CA-S2E-LC architecture can significantly enhance communication reliability and capacity compared with the traditional monolithic satellite. Furthermore, the workflow of the architecture is demonstrated to validate the feasibility.

Lightweight 3D Dense Autoencoder Network for Hyperspectral Remote Sensing Image Classification.

The lack of labeled training samples restricts the improvement of Hyperspectral Remote Sensing Image (HRSI) classification accuracy based on deep learning methods. In order to improve the HRSI classification accuracy when there are few training samples, a Lightweight 3D Dense Autoencoder Network (L3DDAN) is proposed. Structurally, the L3DDAN is designed as a stacked autoencoder which consists of an encoder and a decoder. The encoder is a hybrid combination of 3D convolutional operations and 3D dense block for extracting deep features from raw data. The decoder composed of 3D deconvolution operations is designed to reconstruct data. The L3DDAN is trained by unsupervised learning without labeled samples and supervised learning with a small number of labeled samples, successively. The network composed of the fine-tuned encoder and trained classifier is used for classification tasks. The extensive comparative experiments on three benchmark HRSI datasets demonstrate that the proposed framework with fewer trainable parameters can maintain superior performance to the other eight state-of-the-art algorithms when there are only a few training samples. The proposed L3DDAN can be applied to HRSI classification tasks, such as vegetation classification. Future work mainly focuses on training time reduction and applications on more real-world datasets.

FDA Approval Summary: Tucatinib with Trastuzumab for Advanced Unresectable or Metastatic, Chemotherapy Refractory, HER2-Positive RAS Wild-Type Colorectal Cancer.

On January 19, 2023, the FDA granted accelerated approval to tucatinib in combination with trastuzumab for the treatment of patients with unresectable or metastatic RAS wild-type, HER2-positive colorectal cancer who have received prior treatment with fluoropyrimidine, oxaliplatin, and irinotecan. Approval was based on the pooled analysis of patients receiving tucatinib in combination with trastuzumab in MOUNTAINEER (NCT03043313), an open-label, multicenter trial. The primary endpoint was overall response rate (ORR) by RECIST 1.1 as per blinded central review committee (BIRC) assessment. The main secondary endpoint was duration of response (DOR) per BIRC assessment. Eighty-four eligible patients received the combination tucatinib and trastuzumab. With a median follow-up of 16 months, the ORR was 38% [95% confidence interval (CI): 28-49] and median DOR was 12.4 months (95% CI: 8.5-20.5); 81% of responders had a response lasting more than 6 months. The most common adverse reactions observed in at least 20% of patients receiving tucatinib in combination with trastuzumab were diarrhea, fatigue, rash, nausea, abdominal pain, infusion-related reactions, and fever. FDA concluded that the magnitude of ORR and durable responses observed in patients treated with tucatinib in combination with trastuzumab in the MOUNTAINEER trial are clinically meaningful, particularly in the context of a disease with estimated survival of 6-7 months with available therapy. This is the first approval for the subset of patients with HER2-positive colorectal cancer. This article summarizes the FDA's thought process and review of the data supporting this accelerated approval.

[Acupuncture for glaucoma-induced optic atrophy: a randomized controlled trial].

OBJECTIVE: To observe the clinical effect of acupuncture for glaucoma-induced optic atrophy. METHODS: A total of 70 patients (89 affected eyes) with glaucoma-induced optic atrophy were randomized into an observation group and a control group, 35 cases in each group. The control group was given basic western medicine treatment. In the observation group, on the basis of the treatment in the control group, acupuncture was applied at main acupoints i.e. Baihui (GV 20), Shangjingming (Extra), Chengqi (ST 1), Fengchi (GB 20), Zusanli (ST 36), combined with supplementary acupoints based on syndrome differentiation, once every three days, twice a week. The treatment for 3 months was required in both groups. Before treatment, after treatment and in follow-up of 6 months after treatment, the best corrected visual acuity (BCVA), intraocular pressure (IOP), indexes of visual field (visual field index [VFI], mean deviation [MD], pattern standard deviation [PSD]) and mean thickness of retinal nerve fiber layer (RNFL) were observed in the two groups. RESULTS: Compared before treatment, BCVA was decreased after treatment and in follow-up in the control group (P<0.05); in the follow-up, BCVA in the observation group was higher than that in the control group (P<0.05). On each time point before and after treatment, there was no significant difference within or between the two groups (P>0.05). After treatment and in the follow-up, the mean thickness of RNFL was larger than the control group (P<0.05). CONCLUSION: On the basis of the basic western medicine treatment, acupuncture can delay the decline of vision and the thinning of retinal nerve fiber layer in patients with glaucoma-induced optic atrophy.

IGF2BP3 aggravates lung adenocarcinoma progression by modulation of PI3K/AKT signaling pathway.

OBJECTIVES: The tumor-promoting function of IGF2BP3 has been reported in several cancers. The present study aimed to explore the function and molecular mechanisms of IGF2BP3 are elusive in lung adenocarcinoma (LUAD). METHODS: IGF2BP3 expression in LUAD and its prognostic value were estimated by bioinformatics. RT-qPCR was employed to detect the expression of IGF2BP3 and confirm the transfection efficiency following the knockdown or overexpression of IGF2BP3. Functional assays, including CCK-8, TUNEL, and Transwell assays, were used to determine the role of IGF2BP3 in tumor cell viability, apoptosis, migration and invasion. Gene Set Enrichment Analysis (GSEA) was used to identify signaling pathways related to IGF2BP3 expression. The effects of IGF2BP3 on the PI3K/AKT pathway were detected by western blotting. RESULTS: In this study, we found that IGF2BP3 was overexpressed in LUAD, and patients with high IGF2BP3 levels had a lower probability of overall survival. Moreover, ectopic expression of IGF2BP3 enhanced cell viability and metastasis, and reduced apoptosis. Conversely, IGF2BP3 silencing reduced the viability, migration, and invasion while enhancing the apoptosis of LUAD cells. In addition, it was disclosed that overexpression of IGF2BP3 could activate PI3K/AKT signaling in LAUD, while silencing of IGF2BP3 deactivated this pathway. Moreover, 740Y-P (PI3K agonist) reversed the inhibitory effects on cell viability and metastasis, and the promotion effect on metastasis caused by IGF2BP3 silencing. CONCLUSION: Our findings demonstrated that IGF2BP3 contributed to the tumorigenesis of LUAD by activating the PI3K/AKT signaling.

FDA Approval Summary: Pembrolizumab, Atezolizumab, and Cemiplimab-rwlc as Single Agents for First-Line Treatment of Advanced/Metastatic PD-L1-High NSCLC.

FDA's approval of cemiplimab-rwlc on February 22, 2021, follows prior approvals of pembrolizumab and atezolizumab for similar indications as first-line treatment for patients with programmed death ligand-1 (PD-L1)-high advanced non-small cell lung cancer (NSCLC). Approvals of these anti-PD-L1 agents were supported by statistically significant and clinically meaningful improvements in overall survival (OS) in international, multicenter, active-controlled randomized trials. In KEYNOTE-024, the OS HR was 0.60 [95% confidence interval (CI), 0.41-0.89; P = 0.005] favoring pembrolizumab over platinum-doublet chemotherapy. In IMpower110, the OS HR was 0.59 (95% CI, 0.40-0.89; P = 0.0106) favoring atezolizumab over platinum-doublet chemotherapy. In Study 1624, the OS HR was 0.68 (95% CI, 0.53-0.87; P = 0.0022) favoring cemiplimab-rwlc over platinum-doublet chemotherapy. The progression-free survival (PFS) effect sizes for these anti-PD-L1 antibodies were also comparable across their respective registrational trials, and their safety profiles were consistent with the anti-PD-L1 class adverse event profile. The consistent survival benefits and manageable toxicity profiles of these single-agent anti-PD-L1 antibodies have established them as important treatment options in the PD-L1-high NSCLC treatment landscape. FDA approvals of these anti-PD-L1 antibodies, based on their favorable benefit-risk profiles, present effective chemotherapy-free therapeutic options for patients with advanced PD-L1-high NSCLC in the United States.

FDA Approval Summary: Gilteritinib for Relapsed or Refractory Acute Myeloid Leukemia with a FLT3 Mutation.

On November 28, 2018, the FDA approved gilteritinib (Xospata; Astellas), a small-molecule FMS-like tyrosine kinase 3 (FLT3) inhibitor, for treatment of relapsed or refractory acute myeloid leukemia with a FLT3 mutation as detected by an FDA-approved test. In the ADMIRAL study, patients were randomized 2:1 to receive gilteritinib or standard chemotherapy and stratified by response to first-line treatment and intensity of prespecified chemotherapy. Efficacy was established on interim analysis on the basis of complete remission (CR) + CR with partial hematologic recovery (CRh) rate, duration of CR + CRh, and conversion from transfusion dependence to transfusion independence in 138 patients in the gilteritinib arm. With median follow-up of 4.6 months [95% confidence interval (CI), 2.8-15.8 months] at interim analysis, the CR + CRh rate was 21% (95% CI, 15%-29%), median duration of CR + CRh was 4.6 months (range, 0.1-15.8+), and conversion from transfusion dependence to transfusion independence was 31%. Revised labeling approved on May 29, 2019 included the results of the final analysis, showing an improvement in overall survival (OS) with gilteritinib compared with chemotherapy (HR, 0.64; 95% CI, 0.49-0.83; one-sided P = 0.0004; median OS, 9.3 vs. 5.6 months). The OS benefit was observed in both high and low chemotherapy intensity subgroups. Labeling includes a boxed warning for differentiation syndrome and warnings for posterior reversible encephalopathy syndrome, QT prolongation, pancreatitis, and embryo-fetal toxicity. Safe use requires frequent monitoring of electrocardiograms and blood chemistries. Assessments of long-term safety are pending.

Simultaneous roxarsone photocatalytic degradation and arsenic adsorption removal by TiO2/FeOOH hybrid.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) is an extensively used organoarsenic feed additive. The effective removal of arsenic from roxarsone degradation before discharging is of great importance for controlling artificial arsenic pollution in aquatic environment. In this study, a bifunctional TiO2/ferrihydrite (TiO2/FeOOH) hybrid was synthesized by a hydrothermal method for the simultaneously photocatalytic degradation of roxarsone and adsorption removal of released arsenic. The analysis of the prepared TiO2/FeOOH by field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), Raman spectra, X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) confirmed the successful formation of the hybrid of crystalline TiO2 and no crystalline FeOOH. TiO2/FeOOH hybrid had better adsorption capacity for As(V) than roxarsone. Compared to TiO2, the TiO2/FeOOH hybrid exhibited much superior UV-driven photocatalytic activities for roxarsone degradation. After 12 h irradiation, more than 96% of roxarsone was degraded by 1:1 TiO2/FeOOH hybrid, and the released As(V) was simultaneously removed from the solution. The residual As(V) concentration was lower than 0.02 mg L-1. The reusability test indicated that TiO2/FeOOH hybrid had excellent stability and reliability. The possible mechanism of roxarsone degradation and released inorganic arsenics removal by this hybrid was also proposed. These results clearly indicated that the TiO2/FeOOH hybrid could be used for the removal of roxarsone and its degradation product.

FDA Approval Summary: Atezolizumab Plus Paclitaxel Protein-bound for the Treatment of Patients with Advanced or Metastatic TNBC Whose Tumors Express PD-L1.

On March 8, 2019, the FDA granted accelerated approval to atezolizumab in combination with paclitaxel protein-bound for the treatment of adult patients with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC) whose tumors express PD-L1 [PD-L1 stained tumor-infiltrating immune cells (IC) of any intensity covering ≥1% of the tumor area], as determined by an FDA-approved test. Approval was based on data from IMpassion130, which randomized patients to receive atezolizumab or placebo in combination with paclitaxel protein-bound. Investigator-assessed progression-free survival (PFS) in the intent-to-treat (ITT) and PD-L1-positive populations were coprimary endpoints. After 13-month median follow-up, the estimated median PFS in the PD-L1-positive population was 7.4 months in the atezolizumab arm and 4.8 months in the placebo arm [HR = 0.60; 95% confidence interval (CI), 0.48-0.77]. Overall survival (OS) results were immature with 43% deaths in the ITT population, representing 59% of the OS events required to perform the final OS analysis. Adverse reactions occurring in ≥20% of patients receiving atezolizumab with paclitaxel protein-bound were alopecia, peripheral neuropathies, fatigue, nausea, diarrhea, anemia, constipation, cough, headache, neutropenia, vomiting, and decreased appetite. Accelerated approval was appropriate taking into account the unmet medical need along with the immaturity of the OS results and potential for PFS in the PD-L1-expressing population to predict clinical benefit.

FDA Approval Summary: (Daunorubicin and Cytarabine) Liposome for Injection for the Treatment of Adults with High-Risk Acute Myeloid Leukemia.

On August 3, 2017, the FDA granted regular approval to Vyxeos (also known as CPX-351; Jazz Pharmaceuticals), a liposomal formulation of daunorubicin and cytarabine in a fixed combination, for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia (t-AML) or acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC). Approval was based on data from Study CLTR0310-301, a randomized, multicenter, open-label, active-controlled trial comparing Vyxeos with a standard combination of daunorubicin and cytarabine ("7+3") in 309 patients 60-75 years of age with newly diagnosed t-AML or AML-MRC. Because of elemental copper concerns with the Vyxeos formulation, patients with Wilson disease were excluded from the study. Vyxeos demonstrated an improvement in overall survival (HR 0.69; 95% confidence interval, 0.52-0.90; P = 0.005) with an estimated median overall survival of 9.6 months compared with 5.9 months for the "7+3" control arm. The toxicity profile of Vyxeos was similar to that seen with standard "7+3" with the exception of more prolonged neutropenia and thrombocytopenia on the Vyxeos arm. Because the pharmacology of Vyxeos differs from that of other formulations of daunorubicin and cytarabine, labeling includes a warning against interchanging formulations during treatment. This is the first FDA-approved treatment specifically for patients with t-AML or AML-MRC.

FDA Approval: Ribociclib for the Treatment of Postmenopausal Women with Hormone Receptor-Positive, HER2-Negative Advanced or Metastatic Breast Cancer.

On March 13, 2017, the FDA approved ribociclib (KISQALI; Novartis Pharmaceuticals Corp.), a cyclin-dependent kinase 4/6 inhibitor, in combination with an aromatase inhibitor as initial endocrine-based therapy for the treatment of postmenopausal women with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer. The approval was based on a randomized, double-blind, placebo-controlled, international clinical trial (MONALEESA-2). A total of 668 patients were randomized to receive either ribociclib plus letrozole (n = 334) or placebo plus letrozole (n = 334). An improvement in progression-free survival (PFS) was observed in patients receiving ribociclib plus letrozole compared with patients receiving placebo plus letrozole [HR = 0.556; 95% confidence interval (CI), 0.429-0.720]. Overall response rate (ORR) in patients with measurable disease was 52.7% (95% CI, 46.6-58.9) in the ribociclib plus letrozole arm and 37.1% (95% CI, 31.1-43.2) in the placebo plus letrozole arm. Overall survival data were immature. The most common adverse reactions observed in 20% or more of patients taking ribociclib were neutropenia, nausea, fatigue, diarrhea, leukopenia, alopecia, vomiting, constipation, headache, and back pain. This article summarizes FDA decision-making and data supporting the approval of ribociclib. Clin Cancer Res; 24(13); 2999-3004. ©2018 AACRSee related commentary by Spring and Bardia, p. 2981.

FDA Approval Summary: Atezolizumab for the Treatment of Patients with Progressive Advanced Urothelial Carcinoma after Platinum-Containing Chemotherapy.

Until recently in the United States, no products were approved for second-line treatment of advanced urothelial carcinoma. On May 18, 2016, the U.S. Food and Drug Administration approved atezolizumab for the treatment of patients with locally advanced or metastatic urothelial carcinoma whose disease progressed during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy. Atezolizumab is a programmed death-ligand 1 (PD-L1) blocking antibody and represents the first approved product directed against PD-L1. This accelerated approval was based on results of a single-arm trial in 310 patients with locally advanced or metastatic urothelial carcinoma who had disease progression after prior platinum-containing chemotherapy. Patients received atezolizumab 1,200 mg intravenously every 3 weeks until disease progression or unacceptable toxicity. Key efficacy measures were objective response rate (ORR), as assessed by Independent Review per RECIST 1.1, and duration of response (DoR). With a median follow-up of 14.4 months, confirmed ORR was 14.8% (95% CI: 11.1, 19.3) in all treated patients. Median DoR was not reached and response durations ranged from 2.1+ to 13.8+ months. Of the 46 responders, 37 patients had an ongoing response for ≥ 6 months. The most common adverse reactions (≥20%) were fatigue, decreased appetite, nausea, urinary tract infection, pyrexia, and constipation. Infection and immune-related adverse events also occurred, including pneumonitis, hepatitis, colitis, endocrine disorders, and rashes. Overall, the benefit-risk assessment was favorable to support accelerated approval. The observed clinical benefits need to be verified in confirmatory trial(s). IMPLICATIONS FOR PRACTICE: This accelerated approval of atezolizumab for second-line use in advanced urothelial carcinoma provides patients with an effective, novel treatment option for the management of their disease. This represents the first immunotherapy approved in this disease setting.

FDA Approval of Palbociclib in Combination with Fulvestrant for the Treatment of Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer.

On February 19, 2016, the FDA approved palbociclib (Ibrance, Pfizer) for use in combination with fulvestrant (Faslodex, AstraZeneca) for the treatment of women with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer (MBC) with disease progression following endocrine therapy. The approval was based on the results of a randomized, double-blind, placebo-controlled trial conducted in 521 pre- and postmenopausal women with HR-positive, HER2-negative advanced or MBC. Patients were randomized (2:1) to receive palbociclib plus fulvestrant (n = 347) or placebo plus fulvestrant (n = 174). The primary endpoint was investigator-assessed progression-free survival (PFS). A statistically significant and clinically meaningful improvement in PFS (9.5 months vs. 4.6 months) was observed in patients receiving palbociclib plus fulvestrant [HR 0.46; 95% confidence interval (CI), 0.36-0.59; P < 0.0001]. Safety data confirmed the known adverse reaction profile of palbociclib. The most common adverse reactions (>20%) in patients treated with palbociclib were neutropenia, leukopenia, infections, fatigue, nausea, anemia, stomatitis, headache, diarrhea, and thrombocytopenia. This approval was granted in the context of a prior accelerated approval for palbociclib in combination with letrozole in patients with HR-positive, HER2-negative advanced breast cancer as initial endocrine-based therapy. Clin Cancer Res; 22(20); 4968-72. ©2016 AACR.

Synthesis, characterization, cytotoxicity of mixed ligand complexes of palladium(II) with dipyrido[3,2-d:2',3'-f]quinoxaline/dipyrido[3,2-a:2',3'-c](6,7,8,9-tetrahydro)phenazine and 4-toluensulfonyl-L-amino acid dianion.

Ten novel palladium(II) complexes with dipyrido[3,2-d:2',3'-f]quinoxaline (Dpq)/dipyrido[3,2-a:2',3'-c](6,7,8,9-tetrahydro)phenazine (Dpqc) and 4-toluensulfonyl-L-amino acid dianion, [Pd(Dpq)(TsvalNO)]·H2O (1a), [Pd(Dpq)(TsileNO)]·H2O (1b), [Pd(Dpq)(TsserNO)] (1c), [Pd(Dpq)(TsthrNO)]·1.5H2O (1d), [Pd(Dpq)(TsleuNO)]·0.5H2O (1e), [Pd(Dpq)(TspheNO)] (1f), [Pd(Dpqc)(TsvalNO)] (2a), [Pd(Dpqc)(TsileNO)] (2b), [Pd(Dpqc)(TsserNO)]·H2O (2c) and [Pd(Dpqc)(TsthrNO)]·0.5H2O (2d) have been synthesized and characterized by elemental analysis, IR, UV, (1)H NMR and mass spectrometry techniques. Crystal structure of the complex 1f has been determined by X-ray diffraction. The cytotoxicity was tested by MTT assay. The results indicated that the complexes 1a and 2a showed better cytotoxicity than cisplatin against MCF-7. The complex 1e had higher cytotoxicity than cisplatin against K562. Both the N donating ligands and the amino acid have important effects on the cytotoxicity.

Metabolism and disposition of ABT-894, a novel α4ß2 neuronal acetylcholine receptor agonist, in mice and monkeys.

1. Metabolism and disposition of ABT-894 was investigated in hepatocytes, in mice and monkeys receiving [(14)C]ABT-894. 2. In hepatocytes, turnover rate of ABT-894 was slow in all species with more than 90% of parent remaining. M3 (carbamoyl glucuronide) and M6 (mono-oxidation) were detected across species. 3. ABT-894 showed species-specific disposition profiles. ABT-894 was primarily eliminated by renal secretion in mice. Whereas, monkey mainly cleared ABT-894 metabolically. 4. ABT-894 underwent two primary routes of metabolism in monkeys: N-carbamoyl glucuronidation to form M3 and oxidation product M1. M3 was the major metabolite in monkey excreta. M3 was observed in mice urine. Circulating levels of M3 in terms of M3/ABT-894 ratios were essentially absent in mice, but were high in monkeys. 5. Understanding the species difference in the clearance mechanism is the key to the accurate projection of the human clearance and preclinical safety assessment. Lack of species difference in the metabolism of ABT-894 in hepatocytes certainly creates a challenge in predicting its metabolism and pharmacokinetics in human. Based on available metabolism and pharmacokinetic data of ABT-894 in human, monkey is the preferred species in predicting human clearance since it presents a similar clearance mechanism from that observed in human.

Glutamate racemase dimerization inhibits dynamic conformational flexibility and reduces catalytic rates.

Glutamate racemase (RacE) is a bacterial enzyme that converts l-glutamate to d-glutamate, an essential precursor for peptidoglycan synthesis. In prior work, we have shown that both isoforms cocrystallize with d-glutamate as dimers, and the enzyme is in a closed conformation with limited access to the active site [May, M., et al. (2007) J. Mol. Biol. 371, 1219-1237]. The active site of RacE2 is especially restricted. We utilize several computational and experimental approaches to understand the overall conformational dynamics involved during catalysis when the ligand enters and the product exits the active site. Our steered molecular dynamics simulations and normal-mode analysis results indicate that the monomeric form of the enzyme is more flexible than the native dimeric form. These results suggest that the monomeric enzyme might be more active than the dimeric form. We thus generated site-specific mutations that disrupt dimerization and find that the mutants exhibit significantly higher catalytic rates in the d-Glu to l-Glu reaction direction than the native enzyme. Low-resolution models restored from solution X-ray scattering studies correlate well with the first six normal modes of the dimeric form of the enzyme, obtained from NMA. Thus, along with the local active site residues, global domain motions appear to be implicated in the catalytically relevant structural dynamics of this enzyme and suggest that increased flexibility may accelerate catalysis. This is a novel observation that residues distant from the catalytic site restrain catalytic activity through formation of the dimer structure.

A noncovalent class of papain-like protease/deubiquitinase inhibitors blocks SARS virus replication.

We report the discovery and optimization of a potent inhibitor against the papain-like protease (PLpro) from the coronavirus that causes severe acute respiratory syndrome (SARS-CoV). This unique protease is not only responsible for processing the viral polyprotein into its functional units but is also capable of cleaving ubiquitin and ISG15 conjugates and plays a significant role in helping SARS-CoV evade the human immune system. We screened a structurally diverse library of 50,080 compounds for inhibitors of PLpro and discovered a noncovalent lead inhibitor with an IC(50) value of 20 microM, which was improved to 600 nM via synthetic optimization. The resulting compound, GRL0617, inhibited SARS-CoV viral replication in Vero E6 cells with an EC(50) of 15 microM and had no associated cytotoxicity. The X-ray structure of PLpro in complex with GRL0617 indicates that the compound has a unique mode of inhibition whereby it binds within the S4-S3 subsites of the enzyme and induces a loop closure that shuts down catalysis at the active site. These findings provide proof-of-principle that PLpro is a viable target for development of antivirals directed against SARS-CoV, and that potent noncovalent cysteine protease inhibitors can be developed with specificity directed toward pathogenic deubiquitinating enzymes without inhibiting host DUBs.

Structure-based design, synthesis, and biological evaluation of peptidomimetic SARS-CoV 3CLpro inhibitors.

Structure-based design, synthesis, and biological evaluation of a series of peptidomimetic severe acute respiratory syndrome-coronavirus chymotrypsin-like protease inhibitors are described. These inhibitors were designed and synthesized based upon our X-ray crystal structure of inhibitor 1 bound to SARS-CoV 3CLpro. Incorporation of Boc-Ser as the P(4)-ligand resulted in enhanced SARS-CoV 3CLpro inhibitory activity. Structural analysis of the inhibitor-bound X-ray structure revealed high binding affinity toward the enzyme.