A selective small-molecule STAT5 PROTAC degrader capable of achieving tumor regression in vivo.

Signal transducer and activator of transcription 5 (STAT5) is an attractive therapeutic target, but successful targeting of STAT5 has proved to be difficult. Here we report the development of AK-2292 as a first, potent and selective small-molecule degrader of both STAT5A and STAT5B isoforms. AK-2292 induces degradation of STAT5A/B proteins with an outstanding selectivity over all other STAT proteins and more than 6,000 non-STAT proteins, leading to selective inhibition of STAT5 activity in cells. AK-2292 effectively induces STAT5 depletion in normal mouse tissues and human chronic myeloid leukemia (CML) xenograft tissues and achieves tumor regression in two CML xenograft mouse models at well-tolerated dose schedules. AK-2292 is not only a powerful research tool with which to investigate the biology of STAT5 and the therapeutic potential of selective STAT5 protein depletion and inhibition but also a promising lead compound toward ultimate development of a STAT5-targeted therapy.

A gastrointestinal locally activating Janus kinase inhibitor to treat ulcerative colitis.

In this study, we integrated machine learning (ML), structure-tissue selectivity-activity-relationship (STAR), and wet lab synthesis/testing to design a gastrointestinal (GI) locally activating JAK inhibitor for ulcerative colitis treatment. The JAK inhibitor achieves site-specific efficacy through high local GI tissue selectivity while minimizing the requirement for JAK isoform specificity to reduce systemic toxicity. We used the ML model (CoGT) to classify whether the designed compounds were inhibitors or noninhibitors. Then we used the regression ML model (MTATFP) to predict their IC50 against related JAK isoforms of predicted JAK inhibitors. The ML model predicted MMT3-72, which was retained in the GI tract, to be a weak JAK1 inhibitor, while MMT3-72-M2, which accumulated in only GI tissues, was predicted to be an inhibitor of JAK1/2 and TYK2. ML docking methods were applied to simulate their docking poses in JAK isoforms. Application of these ML models enabled us to limit our synthetic efforts to MMT3-72 and MMT3-72-M2 for subsequent wet lab testing. The kinase assay confirmed MMT3-72 weakly inhibited JAK1, and MMT3-72-M2 inhibited JAK1/2 and TYK2. We found that MMT3-72 accumulated in the GI lumen, but not in GI tissue or plasma, but released MMT3-72-M2 accumulated in colon tissue with minimal exposure in the plasma. MMT3-72 achieved superior efficacy and reduced p-STAT3 in DSS-induced colitis. Overall, the integration of ML, the structure-tissue selectivity-activity-relationship system, and wet lab synthesis/testing could minimize the effort in the optimization of a JAK inhibitor to treat colitis. This site-specific inhibitor reduces systemic toxicity by minimizing the need for JAK isoform specificity.

In Vitro Predictive Dissolution Test Should Be Developed and Recommended as a Bioequivalence Standard for the Immediate-Release Solid Oral Dosage Forms of the Highly Variable Mycophenolate Mofetil.

The prodrug mycophenolate mofetil (MMF), which is presystemically hydrolyzed into the pharmacologically active compound mycophenolic acid (MPA), has been widely used for the prophylaxis of acute allograft rejection in solid organ transplantation. However, the huge variability in the plasma concentration level makes the development of MMF drug products difficult due to the great challenge of meeting the traditional bioequivalence (BE) limits. Numerous models have been developed in the past decade to explain the variability, with the emphasis on characterizing the enterohepatic circulation. While the variability arising from systemic appearance can also contribute to the remarkable MPA variability to a great extent, it has been ignored for long for this Biopharmaceutics Classification System class 2 drug. To improve the design of the BE study for this highly variable (HV) drug, the variability of MMF pharmacokinetic (PK) profiles focusing on the absorption process was explored in a population approach. A total of 81 Chinese adult liver transplant recipients were enrolled and had their plasma concentrations of MPA and its metabolites measured by HPLC during one visit or multiple visits in a long-term MMF regimen. The population models were developed using NONMEM, and the data and the results of the model were analyzed by R. Two population PK models of MMF focusing on the absorption process were developed based on the plasma concentrations of MPA and its major metabolite 7-O-MPA-ß-glucuronide (MPAG). The MPA PK profiles were best characterized by a two-compartment disposition model with zero inter-individual variability (IIV) of elimination coefficient (K20), lag time, but considerable intra-individual variability (IAV) in the form of inter-occasion variability regarding systemic appearance coefficient, K20, and central volume of distribution, when just using MPA plasma concentrations as observations. The second model took into consideration the EHC by including MPAG profiles as well. The results from both models showcased that the IAV played a far more significant role than the IIV in accounting for the variability of the MMF systemic appearance. This is in line with what was found in the BE study: the within-subject variability (WSV) of BE measures largely exceeded the corresponding between-subject variability. The great WSV of MMF can be mechanistically explained by the interplay of dissolution and solubility with the gastrointestinal (GI) physiological dynamics, especially the gastric emptying (GE) in the fasting state regulated by migrating motor complex, and GE and pH variations in the fed state by the caloric content with irregular patterns of GI motility and secretion. The results implied that for the immediate-release solid oral dosage forms of MMF, running a regular in vitro dissolution test for the fasting state and developing a predictive in vitro dissolution test with sufficient simulation of the GE dynamics and proximal small intestinal pH fluctuations for the fed state would be excellent surrogates for the in vivo BE test. Furthermore, a physiologically based predictive in vitro dissolution test under both fasting and fed conditions would be a new trend for the BE studies of all other HV drug products.

Structure-Activity relationship of 1-(Furan-2ylmethyl)Pyrrolidine-Based Stimulation-2 (ST2) inhibitors for treating graft versus host disease.

An elevated plasma level of soluble ST2 (sST2) is a risk biomarker for graft-versus-host disease (GVHD) and death in patients receiving hematopoietic cell transplantation (HCT). sST2 functions as a trap for IL-33 and amplifies the pro-inflammatory type 1 and 17 response while suppressing the tolerogenic type 2 and regulatory T cells activation during GVHD development. We previously identified small-molecule ST2 inhibitors particularly iST2-1 that reduces plasma sST2 levels and improved survival in two animal models. Here, we reported the structure-activity relationship of the furanylmethylpyrrolidine-based ST2 inhibitors based on iST2-1. Based on the biochemical AlphaLISA assay, we improved the activity of iST2-1 by 6-fold (∼6 µM in IC50 values) in the inhibition of ST2/IL-33 and confirmed the activities of the compounds in a cellular reporter assay. To determine the inhibition of the alloreactivity in vitro, we used the mixed lymphocyte reaction assay to demonstrate that our ST2 inhibitors decreased CD4+ and CD8+ T cells proliferation and increased Treg population. The data presented in this work are critical to the development of ST2 inhibitors in future.

Combined p53- and PTEN-deficiency activates expression of mesenchyme homeobox 1 (MEOX1) required for growth of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive cancer subtype for which effective therapies are unavailable. TNBC has a high frequency of tumor protein p53 (Tp53/p53)- and phosphatase and tensin homolog (PTEN) deficiencies, and combined p53- and PTEN-deficiency is associated with poor prognosis and poor response to anticancer therapies. In this study, we discovered that combined p53- and PTEN-deficiency in TNBC activates expression of the transcription factor mesenchyme homeobox 1 (MEOX1). We found that MEOX1 is expressed only in TNBC cells with frequent deficiencies in p53 and PTEN, and that its expression is undetectable in luminal A, luminal B, and HER2+ subtypes, as well as in normal breast cells with wild-type (WT) p53 and PTEN. Notably, siRNA knockdown of both p53 and PTEN activated MEOX1 expression in breast cancer cells, whereas individual knockdowns of either p53 or PTEN had only minimal effects on MEOX1 expression. MEOX1 knockdown abolished cell proliferation of p53- and PTEN-deficient TNBC in vitro and inhibited tumor growth in vivo, but had no effect on the proliferation of luminal and HER2+ cancer cells and normal breast cells. RNA-Seq and immunoblotting analyses showed that MEOX1 knockdown decreased expression of tyrosine kinase 2 (TYK2), signal transducer and activator of transcription 5B (STAT5B), and STAT6 in p53- and PTEN-deficient TNBC cells. These results reveal the effects of combined p53- and PTEN-deficiency on MEOX1 expression and TNBC cell proliferation, suggesting that MEOX1 may serve as a potential therapeutic target for managing p53- and PTEN-deficient TNBC.

Carboxypeptidase A4 negatively correlates with p53 expression and regulates the stemness of breast cancer cells.

Background: Triple-negative breast cancer (TNBC) is an aggressive cancer subtype lacking effective treatment options, and p53 is the most frequently mutated or deleted gene. Carboxypeptidase A4 (CPA4) is an extracellular metallocarboxypeptidase, which was closely associated with aggressiveness. Although a recent study indicated that CPA4 could induce epithelial­mesenchymal transition in breast cancer cells, no studies investigated its stemness-related function and the correlation between CPA4 and p53 in TNBC. In this study, we aimed to investigate the CPA4 levels in breast cancer tissues and analyze its association with p53, and study its roles in cancer stemness maintenance. Methods: CPA4 mRNA level and its prognostic value were analyzed by using online database UALCAN (http://ualcan.path.uab.edu) and Kaplan-Meier plotter (www.kmplot.com), respectively. The expression of CPA4, p53 and ALDH1A1 in breast cancer and adjacent normal tissues were evaluated by IHC using the corresponding primary antibodies on a commercial tissue array (Shanghai Biochip Co., Ltd., Shanghai, China). siRNA knockdown was used to study the function of proliferation, colony formation assay and sphere formation in serum-free medium. Results: Analysis of the UALCAN datasets identified that CPA4 mRNA levels were elevated in TNBC, especially in the TP53-mutant subgroup. Furthermore, high levels of CPA4 mRNA were significantly associated with unfavourable overall survival OS in breast cancer patients. Immunohistochemistical analysis demonstrated that CPA4 levels were elevated in 32.1% of breast cancer samples (45/140), and the positive rates of ALDH1A1 and p53 in the breast cancer tissues were 25% (35/140) and 50% (70/140), respectively. Statistical analysis revealed high levels of CPA4 was significantly associated with TNBC phenotype. Correlation analysis indicated that CPA4 over-expression was positively associated with ALDH1A1 (P<0.01) and negatively correlated with p53 (P<0.05). In Kaplan-Meier survival analysis, either high CPA4 or ALDH1A1 levels was significantly correlated with poor survival in breast cancer patients. Functional studies demonstrated that down-regulation of CPA4 significantly inhibited TNBC cell proliferation, colony-formation assays in soft agar and sphere formation in serum-free medium. Conclusion: This study demonstrated for the first time that CPA4 was negatively correlates with p53 expression and inhibition of CPA4 could reduce the number of breast cancer cells with stemness property. It might be a potential target for the TNBC treatment.

Albumin Nanoparticle of Paclitaxel (Abraxane) Decreases while Taxol Increases Breast Cancer Stem Cells in Treatment of Triple Negative Breast Cancer.

Triple-negative breast cancer (TNBC) has a high rate of metastasis, which is associated with breast cancer stem-like cells (CSCs). Although Taxol (micelle formulation of paclitaxel) is the first line chemotherapy to treat TNBC, it increases CSCs in residual tumors. Abraxane, albumin nanoparticle of paclitaxel, showed lower plasma concentration compared to Taxol in both human and animal models, but it is not clear why Abraxane showed superior efficacy to Taxol in treatment of metastatic breast cancer in humans. In this study, we intend to investigate if Abraxane eliminates CSCs for its better efficacy. The results showed that Abraxane showed similar cytotoxicity in SUM149 cells in comparison with Taxol. Although Abraxane showed 3- to 5-fold lower blood drug concentration compared to Taxol, it achieved similar tumor drug concentration and 10-fold higher tumor/plasma ratio in SUM149 xenograft NOD/SCID mouse model. In addition, Abraxane and Taxol showed similar efficacy to shrink the tumor size in orthotopic breast cancer NOD/SCID mouse model. However, Abraxane decreased breast CSCs frequency by 3- to 9-fold, while Taxol increased breast CSCs frequency in an orthotopic breast cancer NOD/SCID mouse model. Furthermore, Abraxane increased 3- to 15-fold intracellular uptake in both ALDH+ CSCs and differentiated ALDH- cells in comparison with Taxol, which provides a mechanism for Abraxane's superior efficacy to eliminate CSCs in comparison with Taxol. Our data suggest albumin nanoparticle Abraxane may have a broad implication to enhance drug's efficacy by eliminating breast cancer stem cells for treatment of metastatic diseases.

Synthesis and structure-activity relationships of thieno[2,3-d]pyrimidines as atypical protein kinase C inhibitors to control retinal vascular permeability and cytokine-induced edema.

Studies demonstrate that small molecule targeting of atypical protein kinase C (aPKC) may provide an effective means to control vascular permeability, prevent edema, and reduce inflammation providing novel and important alternatives to anti-VEGF therapies for certain blinding eye diseases. Based on a literature tricyclic thieno[2,3-d]pyrimidine lead (1), an ATP-competitive inhibitor of the aPKC iota (ι) and aPKC zeta (ζ) isoforms, we have synthesized a small series of compounds in 1-2 steps from a readily available chloro intermediate. A single pyridine congener was also made using 2D NMR to assign regiochemistry. Within the parent pyrimidine series, a range of potencies was observed against aPKCζ whereas the pyridine congener was inactive. Selected compounds were also tested for their effect toward VEGF-induced permeability in BREC cells. The most potent of these (7l) was further assayed against the aPKCι isoform and showed a favorable selectivity profile against a panel of 31 kinases, including kinases from the AGC superfamily, with a focus on PKC isoforms and kinases previously shown to affect permeability. Further testing of 7l in a luciferase assay in HEK293 cells showed an ability to prevent TNF-α induced NFκB activation while not having any effect on cell survival. Intravitreal administration of 7l to the eye yielded a complete reduction in permeability in a test to determine whether the compound could block VEGF- and TNFα-induced permeability across the retinal vasculature in a rat model. The compound in mice displayed good microsomal stability and in plasma moderate exposure (AUC and Cmax), low clearance, a long half-life and high oral bioavailability. With IV dosing, higher levels were observed in the brain and eye relative to plasma, with highest levels in the eye by either IV or PO dosing. With a slow oral absorption profile, 7l accumulates in the eye to maintain a high concentration after dosing with higher levels than in plasma. Compound 7l may represent a class of aPKC inhibitors for further investigation.

Application of an innovative high-throughput liquid chromatography-tandem mass spectrometry method for simultaneous analysis of 18 hazardous drugs to rule out accidental acute chemotherapy exposures in health care workers.

OBJECTIVES: Despite safe handling guidelines published by several groups, health care worker exposure to hazardous drugs continues to occur due to suboptimal engineering controls and low use of protective equipment. Simple, multi-target and specific analytical methods are needed so that acute exposures to these drugs in the workplace can be assessed rapidly. Our aim was to develop an analytical method for simultaneous detection and quantification of widely used cancer drugs to rule out accidental acute chemotherapy exposures in health care workers. METHODS: We examined the feasibility of alternate high-performance liquid chromatographic-tandem mass spectrometry methods to simultaneously detect eighteen chemotherapy analytes in plasma and urine. The linear concentration ranges tested during assay development were 0.1-50 ng/mL. After development of a multi-analyte assay protocol, plasma samples (n = 743) from a multi-center cluster-randomized clinical trial (n = 12 sites) of an hazardous drug educational intervention were assayed. Confirmatory assays were performed based on the individual acute-spill case-histories. RESULTS: An innovative HPLC-multiple reaction monitoring-information dependent acquisition-enhanced production ion (MRM-IDA-EPI) analytical method was developed to simultaneously detect: cytarabine, gemcitabine, dacarbazine, methotrexate, topotecan, mitomycin, pemetrexed, irinotecan, doxorubicin, vincristine, vinblastine, ifosamide, cyclophosphamide, vinorelbine, bendamustine, etoposide, docetaxel, and paclitaxel. The retention times ranged from 4 min to 13 min for the analytical run. The limit of detection (MRM-IDA-EPI) and limit of quantitation (MRM) was 0.25 ng/mL and 0.1 ng/mL, respectively for most analytes. No detectable plasma concentrations were measured at baseline, post-intervention and in cases of documented acute spills. Use of a secondary tandem mass spectrometry approach was able to successfully rule out false positive results. CONCLUSIONS: Development of a sensitive high-throughput multi-analyte cancer chemotherapy assay is feasible using an MRM-IDA-EPI method. This method can be used to rapidly rule out systemic exposure to accidental acute chemotherapy spills in health care workers.

Liposomal formulation of HIF-1α inhibitor echinomycin eliminates established metastases of triple-negative breast cancer.

Hypoxia-inducible factor 1α (HIF-1α) is recognized as a prime molecular target for metastatic cancer. However, no specific HIF-1α inhibitor has been approved for clinical use. Here, we demonstrated that in vivo efficacy of echinomycin in solid tumors with HIF-1α overexpression is formulation-dependent. Compared to previously-used Cremophor-formulated echinomycin, which was toxic and ineffective in clinical trials, liposomal-echinomycin provides significantly more inhibition of primary tumor growth and only liposome-formulated echinomycin can eliminate established triple-negative breast cancer (TNBC) metastases, which are the leading cause of death from breast cancer, as available therapies remain minimally effective at this stage. Pharmacodynamic analyses reveal liposomal-echinomycin more potently inhibits HIF-1α transcriptional activity in primary and metastasized TNBC cells in vivo, the latter of which are HIF-1α enriched. The data suggest that nanoliposomal-echinomycin can provide safe and effective therapeutic HIF-1α inhibition and could represent the most potent HIF-1α inhibitor in prospective trials for metastatic cancer.

Probing the interaction between the histone methyltransferase/deacetylase subunit RBBP4/7 and the transcription factor BCL11A in epigenetic complexes.

The transcription factor BCL11A has recently been reported to be a driving force in triple-negative breast cancer (TNBC), contributing to the maintenance of a chemoresistant breast cancer stem cell (BCSC) population. Although BCL11A was shown to suppress γ-globin and p21 and to induce MDM2 expression in the hematopoietic system, its downstream targets in TNBC are still unclear. For its role in transcriptional repression, BCL11A was found to interact with several corepressor complexes; however, the mechanisms underlying these interactions remain unknown. Here, we reveal that BCL11A interacts with histone methyltransferase (PRC2) and histone deacetylase (NuRD and SIN3A) complexes through their common subunit, RBBP4/7. In fluorescence polarization assays, we show that BCL11A competes with histone H3 for binding to the negatively charged top face of RBBP4. To define that interaction, we solved the crystal structure of RBBP4 in complex with an N-terminal peptide of BCL11A (residues 2-16, BCL11A(2-16)). The crystal structure identifies novel interactions between BCL11A and the side of the ß-propeller of RBBP4 that are not seen with histone H3. We next show that BCL11A(2-16) pulls down RBBP4, RBBP7, and other components of PRC2, NuRD, and SIN3A from the cell lysate of the TNBC cell line SUM149. Furthermore, we demonstrate the therapeutic potential of targeting the RBBP4-BCL11A binding by showing that a BCL11A peptide can decrease aldehyde dehydrogenase-positive BCSCs and mammosphere formation capacity in SUM149. Together, our findings have uncovered a previously unidentified mechanism that BCL11A may use to recruit epigenetic complexes to regulate transcription and promote tumorigenesis.

Neonatal Fc Receptor (FcRn) Enhances Tissue Distribution and Prevents Excretion of nab-Paclitaxel.

nab-Paclitaxel ( nab-P), an albumin-bound formulation of paclitaxel, was developed to improve the tolerability and antitumor activity of taxanes. The neonatal Fc receptor (FcRn) is a transport protein that can bind to albumin and regulate the homeostasis of circulating albumin. Therefore, the pharmacokinetics and pharmacodynamics of nab-P may be impacted by FcRn expression. This study aimed to investigate the effects of FcRn on nab-P elimination and distribution to targeted tissues. Wild-type and FcRn-knockout (FcRn-KO) mice were treated with nab-P, mouse-specific nab-P (distribution experiments only), and solvent-based paclitaxel (pac-T). Blood and tissue samples were collected for distribution analyses. Organ, urine, and fecal samples were collected for elimination analyses. The nab-P tissue penetration in the pancreas, fat pad, and kidney of wild-type mice, as reflected by the ratio of tissue/plasma concentration, was significantly higher (ranging from 5 to 80 fold) than that of FcRn-KO mice. In contrast, the tissue penetration of pac-T in these organs of FcRn-KO mice was similar to that of wild-type mice. More importantly, the excretion of nab-P in feces of FcRn-KO mice (45-68%) was significantly higher than that of wild-type mice (26-46%) from 8 to 48 h post treatment. In comparison, the difference of excretion of pac-T in feces between FcRn-KO mice and wild-type mice was smaller than that of nab-P. Furthermore, greater tissue penetration and fecal excretion were observed with nab-P than pac-T in both FcRn-KO and wild-type mice. These findings suggest that FcRn enhances the tissue distribution and penetration of nab-P in the targeted organs, while FcRn prevents excretion of nab-P to feces in the intestinal lumen. The findings support the notion that albumin nanoparticle delivery alters drug distribution and elimination through an FcRn-mediated process to impact drug efficacy and toxicity.

MEOX1 Promotes Tumor Progression and Predicts Poor Prognosis in Human Non-Small-Cell Lung Cancer.

Background: MEOX1 is a homeobox transcriptional factor, and plays essential roles in regulating somite development. Our previous study indicated that MEOX1 is a critical molecular target in mesenchymal-like cancer cells in PTEN-deficient Trastuzumab resistant breast cancer. Despite the potential implication of MEOX1 for the cancer progression, no previous studies examined its level and clinical significance in lung cancer tissues. In this study, we aimed to detect the MEOX1 expression and correlate its level with clinical outcome in non-small-cell lung cancer patients (NSCLC). Methods: MEOX1 gene expression in lung cancer was examined by using the Oncomine database. MEOX1 protein levels were evaluated by IHC using the corresponding primary antibody on two different commercial lung cancer tissue arrays. siRNA knockdown was used to elucidate the function of MEOX1. Results: Analysis of the Oncomine datasets identified that an elevation of MEOX1 in gene amplification in lung cancer tissues in comparison to normal lung tissues. Immunohistochemistical analysis demonstrated that MEOX1 was localized predominantly in the nucleus, and positive rate was 67.3% (111/165) in NSCLC samples. Statistical analysis revealed high levels of MEOX1 significantly correlated with Lymph Node Metastasis and Stage. Kaplan-Meier survival analysis showed that high levels of MEOX1 were significantly associated with unfavorable survival in NSCLC patients, and MEOX1 nucleus staining had worse survival, than did patients with overall expression in lung squamous cell carcinoma patients. Multivariate Cox's regression analysis found that MEOX1 was an independent poor prognostic predictor for patients with NSCLC. Silencing of MEOX1 by specific SiRNA significantly inhibited H460 and H1299 cell proliferation and sphere formation in serum-free medium. Conclusions: Our results firstly indentified that high levels of MEOX1 especially nuclear staining was an independent prognostic factor for NSCLC, and it served a essential roles in the regulation of cell proliferation and colony formation in vitro. It may represent a potential target for the NSCLC treatment.

Synthesis of deuterium-labelled amlexanox and its metabolic stability against mouse, rat, and human microsomes.

As part of a program toward making analogues of amlexanox (1), currently under clinical investigation for the treatment of type 2 diabetes and obesity, we have synthesized derivative 5 in which deuterium has been introduced into two sites of metabolism on the C-7 isopropyl function of amlexanox. The synthesis of 5 was completed in an efficient three-step process utilizing reduction of key olefin 7b to 8 by Wilkinson's catalyst to provide specific incorporation of di-deuterium across the double bond. Compound 5 displayed nearly equivalent potency to amlexanox (IC50 , 1.1µM vs 0.6µM, respectively) against recombinant human TBK1. When incubated with human, rat, and mouse liver microsomes, amlexanox (1) and d2 -amlexanox (5) were stable (t1/2  > 60 minutes) with 1 showing marginally greater stability relative to 5 except for rat liver microsomes. These data show that incorporating deuterium into two sites of metabolism does not majorly suppress Cyp-mediated metabolism relative to amlexanox.

Different Nanoformulations Alter the Tissue Distribution of Paclitaxel, Which Aligns with Reported Distinct Efficacy and Safety Profiles.

Previous studies have shown that different paclitaxel formulations produce distinct anticancer efficacy and safety profiles in animals and humans. This study aimed to investigate the distinct pharmacokinetics and tissue distribution of various nanoformulations of paclitaxel, which may translate into potential differences in safety and efficacy. Four nanoparticle formulations ( nab-paclitaxel, mouse albumin nab-paclitaxel [m -nab-paclitaxel], micellar paclitaxel, and polymeric nanoparticle paclitaxel) as well as solvent-based paclitaxel were intravenously administered to mice. Seventeen blood and tissue samples were collected at different time points. The total paclitaxel concentration in each tissue specimen was measured with liquid chromatography-tandem mass spectrometry. Compared with solvent-based paclitaxel, all four nanoformulations demonstrated decreased paclitaxel exposure in plasma. All nanoformulations were associated with paclitaxel blood-cell accumulation in mice; however, m- nab-paclitaxel was associated with the lowest accumulation. Five minutes after dosing, the total paclitaxel in the tissues and blood was approximately 44% to 57% of the administered dose of all paclitaxel formulations. Paclitaxel was primarily distributed to liver, muscle, intestine, kidney, skin, and bone. Compared with solvent-based paclitaxel, the different nanocarriers altered the distribution of paclitaxel in all tissues with distinct paclitaxel concentration-time profiles. nab-paclitaxel was associated with increased delivery efficiency of paclitaxel in the pancreas compared with the other formulations, consistent with the demonstrated efficacy of nab-paclitaxel in pancreatic cancer. All the nanoformulations led to high penetration in the lungs and fat pad, which potentially points to efficacy in lung and breast cancers. Micellar paclitaxel and polymeric nanoparticle paclitaxel were associated with high paclitaxel accumulation in the heart; thus, the risk of cardiovascular toxicity with these formulations may warrant further investigation. The solvent-based formulation was associated with the poorest paclitaxel penetration in all tissues and the lowest tissue-to-plasma ratio. The different nanocarriers of paclitaxel were associated with distinct pharmacokinetics and tissue distribution, which largely align with the observed efficacy and toxicity profiles in clinical trials.

Linking the Gastrointestinal Behavior of Ibuprofen with the Systemic Exposure between and within Humans-Part 1: Fasted State Conditions.

The goal of this project was to explore and to statistically evaluate the responsible gastrointestinal (GI) factors that are significant factors in explaining the systemic exposure of ibuprofen, between and within human subjects. In a previous study, we determined the solution and total concentrations of ibuprofen as a function of time in aspirated GI fluids, after oral administration of an 800 mg IR tablet (reference standard) of ibuprofen to 20 healthy volunteers in fasted state conditions. In addition, we determined luminal pH and motility pressure recordings that were simultaneously monitored along the GI tract. Blood samples were taken to determine ibuprofen plasma levels. In this work, an in-depth statistical and pharmacokinetic analysis was performed to explain which underlying GI variables are determining the systemic concentrations of ibuprofen between (inter-) and within (intra-) subjects. In addition, the obtained plasma profiles were deconvoluted to link the fraction absorbed with the fraction dissolved. Multiple linear regressions were performed to explain and quantitatively express the impact of underlying GI physiology on systemic exposure of the drug (in terms of plasma Cmax/AUC and plasma Tmax). The exploratory analysis of the correlation between plasma Cmax/AUC and the time to the first phase III contractions postdose (TMMC-III) explains ∼40% of the variability in plasma Cmax for all fasted state subjects. We have experimentally shown that the in vivo intestinal dissolution of ibuprofen is dependent upon physiological variables like, in this case, pH and postdose phase III contractions. For the first time, this work presents a thorough statistical analysis explaining how the GI behavior of an ionized drug can explain the systemic exposure of the drug based on the individual profiles of participating subjects. This creates a scientifically based and rational framework that emphasizes the importance of including pH and motility in a predictive in vivo dissolution methodology to forecast the in vivo performance of a drug product. Moreover, as no extensive first-pass metabolism is considered for ibuprofen, this study demonstrates how intraluminal drug behavior is reflecting the systemic exposure of a drug.

Linking the Gastrointestinal Behavior of Ibuprofen with the Systemic Exposure between and within Humans-Part 2: Fed State.

Exploring the intraluminal behavior of an oral drug product in the human gastrointestinal (GI) tract remains challenging. Many in vivo techniques are available to investigate the impact of GI physiology on oral drug behavior in fasting state conditions. However, little is known about the intraluminal behavior of a drug in postprandial conditions. In a previous report, we described the mean solution and total concentrations of ibuprofen after oral administration of an immediate-release (IR) tablet in fed state conditions. In parallel, blood samples were taken to assess systemic concentrations. The purpose of this work was to statistically evaluate the impact of GI physiology (e.g., pH, contractile events) within and between individuals (intra and intersubject variability) for a total of 17 healthy subjects. In addition, a pharmacokinetic (PK) analysis was performed by noncompartmental analysis, and PK parameters were correlated with underlying physiological factors (pH, time to phase III contractions postdose) and study parameters (e.g., ingested amount of calories, coadministered water). Moreover, individual plasma profiles were deconvoluted to assess the fraction absorbed as a function of time, demonstrating the link between intraluminal and systemic behavior of the drug. The results demonstrated that the in vivo dissolution of ibuprofen depends on the present gastric pH and motility events at the time of administration. Both intraluminal factors were responsible for explaining 63% of plasma Cmax variability among all individuals. For the first time, an in-depth analysis was performed on a large data set derived from an aspiration/motility study, quantifying the impact of physiology on systemic behavior of an orally administered drug product in fed state conditions. The data obtained from this study will help us to develop an in vitro biorelevant dissolution approach and optimize in silico tools in order to predict the in vivo performance of orally administered drug products, especially in fed state conditions.

Optimization of dipeptidic inhibitors of cathepsin L for improved Toxoplasma gondii selectivity and CNS permeability.

The neurotropic protozoan Toxoplasma gondii is the second leading cause of death due to foodborne illness in the US, and has been designated as one of five neglected parasitic infections by the Center for Disease Control and Prevention. Currently, no treatment options exist for the chronic dormant-phase Toxoplasma infection in the central nervous system (CNS). T. gondii cathepsin L (TgCPL) has recently been implicated as a novel viable target for the treatment of chronic toxoplasmosis. In this study, we report the first body of SAR work aimed at developing potent inhibitors of TgCPL with selectivity vs the human cathepsin L. Starting from a known inhibitor of human cathepsin L, and guided by structure-based design, we were able to modulate the selectivity for Toxoplasma vs human CPL by nearly 50-fold while modifying physiochemical properties to be more favorable for metabolic stability and CNS penetrance. The overall potency of our inhibitors towards TgCPL was improved from 2 µM to as low as 110 nM and we successfully demonstrated that an optimized analog 18b is capable of crossing the BBB (0.5 brain/plasma). This work is an important first step toward development of a CNS-penetrant probe to validate TgCPL as a feasible target for the treatment of chronic toxoplasmosis.

Multibuilding Block Janus Synthesized by Seed-Mediated Self-Assembly for Enhanced Photothermal Effects and Colored Brownian Motion in an Optical Trap.

The asymmetrical features and unique properties of multibuilding block Janus nanostructures (JNSs) provide superior functions for biomedical applications. However, their production process is very challenging. This problem has hampered the progress of JNS research and the exploration of their applications. In this study, an asymmetrical multibuilding block gold/iron oxide JNS has been generated to enhance photothermal effects and display colored Brownian motion in an optical trap. JNS is formed by seed-mediated self-assembly of nanoparticle-loaded thermocleavable micelles, where the hydrophobic backbones of the polymer are disrupted at high temperatures, resulting in secondary self-assembly and structural rearrangement. The JNS significantly enhances photothermal effects compared to their homogeneous counterpart after near-infrared (NIR) light irradiation. The asymmetrical distribution of gold and iron oxide within JNS also generates uneven thermophoretic force to display active colored Brownian rotational motion in a single-beam gradient optical trap. These properties indicate that the asymmetrical JNS could be employed as a strong photothermal therapy mediator and a fuel-free nanoscale Janus motor under NIR light.

Targeting deubiquitinase activity with a novel small-molecule inhibitor as therapy for B-cell malignancies.

Usp9x was recently shown to be highly expressed in myeloma patients with short progression-free survival and is proposed to enhance stability of the survival protein Mcl-1. In this study, we found that the partially selective Usp9x deubiquitinase inhibitor WP1130 induced apoptosis and reduced Mcl-1 protein levels. However, short hairpin RNA-mediated knockdown (KD) of Usp9x in myeloma cells resulted in transient induction of apoptosis, followed by a sustained reduction in cell growth. A compensatory upregulation of Usp24, a deubiquitinase closely related to Usp9x, in Usp9x KD cells was noted. Direct Usp24 KD resulted in marked induction of myeloma cell death that was associated with a reduction of Mcl-1. Usp24 was found to sustain myeloma cell survival and Mcl-1 regulation in the absence of Usp9x. Both Usp9x and Usp24 were expressed and activated in primary myeloma cells whereas Usp24 protein overexpression was noted in some patients with drug-refractory myeloma and other B-cell malignancies. Furthermore, we improved the drug-like properties of WP1130 and demonstrated that the novel compound EOAI3402143 dose-dependently inhibited Usp9x and Usp24 activity, increased tumor cell apoptosis, and fully blocked or regressed myeloma tumors in mice. We conclude that small-molecule Usp9x/Usp24 inhibitors may have therapeutic activity in myeloma.