Immunostimulatory and anti-neoplasm effects of a novel palindrome CpG oligodeoxynucleotide in mice.

AIM: DNAs containing unmethylated CpG motifs can stimulate innate and adaptive immunity. The aim of this study was to investigate the immunostimulatory and anti-neoplasm effects of a novel CpG oligodeoxynucleotide, ODN10, in tumor-bearing mice. METHODS: B16 melanoma-bearing C57BL/6 mice were administered ip or sc with ODN10 or conventional CpG ODN1826 on the indicated days post inoculation. The animal survival rate and the inhibitory effect on tumor growth were observed in vivo. B and T lymphocyte proliferation, natural killing cell cytotoxicity and the phagocytic ability of peritoneal macrophages from the animals were determined using [(3)H]-thymidine incorporation assay, 4-h (51)Cr release assay and neutral red chromometry method, respectively. The serum levels of IL-12, IL-4 and IgE were quantified using ELISA assays. Histological examination of tumor tissues was performed after HE staining, and the expression of PCNA, CD63, and CD80 in tumor tissues was analyzed with immunohistochemistry. RESULTS: ODN10 (1, 5 and 25 mg/kg) significantly inhibited the growth and metastasis of the tumor, and significantly prolonged the survival of tumor-bearing mice, as compared with ODN1826. The immune status was suppressed in tumor-bearing mice. Both ODN10 and ODN1826 significantly reversed the suppressed immunoactivities in tumor-bearing mice, which included promoting B and T lymphocyte proliferation, enhancing NK cell and peritoneal macrophage activities, inducing IL-12 secretion and inhibiting IL-4 and IgE secretion. Further, CpG ODNs decreased PCNA and CD63 expression while induced expression of CD80. ODN10 presented more potent activity, and displayed the most prominent immunostimulatory potential. CONCLUSION: ODN10 produces prominent immunomodulatory effects on cellular immunity in tumor-bearing mice, which might help reverse the established Th2-type responses to the Th1-type responses, thus may be used as a potent anti-tumor immunotherapy agent or adjuvant.

Population pharmacokinetics of rhTNFR-Fc in healthy Chinese volunteers and in Chinese patients with Ankylosing spondylitis.

AIM: To investigate the population pharmacokinetics of recombinant human tumor necrosis factor receptor-Fc fusion protein (rhTNFR-Fc) administered via subcutaneous (SC) injection in healthy Chinese volunteers and in Chinese patients with ankylosing spondylitis (AS). METHODS: Thirty-two healthy volunteers were randomly assigned to receive a single SC injection of 12.5, 25, 37.5, or 50 mg of rhTNFR-Fc. Twenty male patients with moderate AS were randomly assigned to receive seven consecutive SC injections of rhTNFR-Fc at either 25 mg twice a week (BIW) or 50 mg once a week (QW). Population pharmacokinetic (PK) analysis was applied to obtain PK parameters of rhTNFR-Fc by the NONMEM method. RESULTS: The data were best described by a one-compartment model with lag time. We found that gender had a significant effect on the apparent clearance (CL/F), with the male CL/F ratio being only 0.665 times the female ratio; the absorption coefficient (F) of multiple dosages of rhTNFR-Fc was only 0.674 times that of a single dosage. The outcome parameters were CL/F (female: 0.168 L/h, male: 0.110 L/h), the apparent volume of distribution (Vd/F: 15.5 L), the absorption rate constant (Ka) (single dosage: 0.0605 h⁻¹, multiple dosage: 0.0408 h⁻¹), and the lag time (T(lag): 1.03 h). The inter-individual variability in the CL/F, Vd/F, Ka, and T(lag) were 33.3%, 42.7%, 55.6%, and 81.8%, respectively. CONCLUSION: Chinese females have a higher CL/F than Chinese males, and multiple dosings can significantly decrease the absorption of rhTNFR-Fc (SC). The population PK parameters of rhTNFR-Fc in healthy Chinese volunteers and patients with AS were similar to those reported for subjects in published American studies.

Optimal design and validation of antiviral siRNA for targeting hepatitis B virus.

AIM: Optimal design of antiviral short-interfering RNA (siRNA) targeting highly divergent hepatitis B virus (HBV) was validated by quantitative structure activity relationship (QSAR) analysis. METHODS: The potency of 23 synthetic siRNAs targeting 23 sites throughout HBV pregenomic RNA were evaluated at 10 nmol/L by determining the inhibition on the expression of S/P/pregenomic mRNA and hepatitis B surface antigen (HBsAg) quantitatively in HepG2.2.15 cells. Genotype homology within HBV genomes was identified through plentiful computational analysis and the multiple linear regression analysis was made to validate the relationship between the functional siRNAs and primary characteristics. Based on the preliminary results, relationships between different determined endpoints [S/P mRNA, HBsAg, C/P mRNA, hepatitis B e antigen (HBeAg) and viral DNA load] and siRNA efficacy evaluation were investigated. RESULTS: Genotype homology, open reading frame (ORF) S/P, X and C had tight correlation with the ability of siRNAs on inhibiting the expression of S/P/Pregenomic mRNA and HBsAg (P<0.01), of which, ORF C was negatively correlated with the siRNA potency (P<0.05). Further study showed that siRNA potency evaluation was influenced by different determined endpoints. P-target siRNAs showed significant inhibition on the S mRNA and HBsAg expression. S-target siRNAs inhibited the expression of S mRNA and HBsAg strongly. X-target siRNAs played active roles in inhibiting all 5 determined endpoints. C-target siRNAs blocked the expression of C mRNA, HBeAg and viral DNA load significantly. CONCLUSION: The antiviral potency of siRNA was relevant to its primary characteristics and determined endpoints were important for siRNA efficacy evaluation for complex genome with overlapping ORF, which was helpful for siRNA optimal design.

Structure-efficacy relationships of immunostimulatory activity of CpG-containing oligodeoxynucleotides on mouse spleen cells.

AIM: To study the relationship between primary structures of oligodeoxynucleotides (ODN) containing unmethylated deoxycytidyldeoxyguanosine (CpG) dinucleotide motifs and their immunostimulatory activities in mouse spleen cells. METHODS: A series of CpG ODN with different primary structures were synthesized. Their capabilities to stimulate mouse spleen cell proliferation were determined by [3H]thymidine incorporation assay. Cytokine (interleukin [IL]-6, IL-12, and IFN-alpha) secretion spectra induced by CpG ODN were assessed by ELISA. The ability of CpG ODN to activate natural killer cells was evaluated by standard 4 h (51)Cr-release assay. Flow cytometry was utilized to examine the expressions of various lymphocyte surface molecules on diverse immunocytes. An effective CpG ODN for murine, ODN1826, was set as the template of modification and the positive control. RESULTS: The immunostimulatory activities of CpG ODN with different sequences and compositions varied markedly, both in character and in extent. It was useless for improving the immunostimulatory activity of ODN1826 by simply increasing the functional hexameric CpG motif number, modifying the site of CpG motifs, or changing the distance between multi-CpG motifs. However, an addition of a self-complementary palindrome structure at the 3'-end, but not the 5'-end of CpG ODN, aroused marked improvement in its activity. Several designed ODN had superior comprehensive immunostimulatory properties compared to ODN1826. CONCLUSION: The immunostimulatory activity of a CpG ODN was relevant to its primary structure. It was useless for promoting immunostimulatory activity to simply change CpG motif number, space, or distance. The 3'-end palindrome structure of CpG ODN is associated with enhanced immunostimulatory activity.

Pharmacokinetics of sifuvirtide, a novel anti-HIV-1 peptide, in monkeys and its inhibitory concentration in vitro.

AIM: To study the pharmacokinetics of sifuvirtide, a novel anti-human immunodeficiency virus (HIV) peptide, in monkeys and to compare the inhibitory concentrations of sifuvirtide and enfuvirtide on HIV-1-infected-cell fusion. METHODS: Monkeys received 1.2 mg/kg iv or sc of sifuvirtide. An on-line solid-phase extraction procedure combined with liquid chromatography tandem mass spectrometry (SPE-LC/MS/MS) was established and applied to determine the concentration of sifuvirtide in monkey plasma. A four-(127)I iodinated peptide was used as an internal standard. Fifty percent inhibitory concentration (IC(50)) of sifuvirtide on cell fusion was determined by co-cultivation assay. RESULTS: The assay was validated with good precision and accuracy. The calibration curve for sifuvirtide in plasma was linear over a range of 4.88-5000 microg/L, with correlation coefficients above 0.9923. After iv or sc administration, the observed peak concentrations of sifuvirtide were 10 626+/-2886 microg/L and 528+/-191 microg/L, and the terminal elimination half-lives (T(1/2)) were 6.3+/-0.9 h and 5.5+/-1.0 h, respectively. After sc, T(max) was 0.25-2 h, and the absolute bioavailability was 49%+/-13%. Sifuvirtide inhibited the syncytium formation between HIV-1 chronically infected cells and uninfected cells with an IC(50) of 0.33 microg/L. CONCLUSION: An on-line SPE-LC/MS/MS approach was established for peptide pharmacokinetic studies. Sifuvirtide was rapidly absorbed subcutaneously into the blood circulation. The T(1/2) of sifuvirtide was remarkably longer than that of its analog, enfuvirtide, reported in healthy monkeys and it conferred a long-term plasma concentration level which was higher than its IC(50) in vitro.

Pharmacokinetics of His-tag recombinant human endostatin in Rhesus monkeys.

AIM: To study the pharmacokinetics and accumulation of an Escherichia coli expressed His-tag fused recombinant human endostatin (rh-endostatin) in Rhesus monkeys. METHODS: Rh-endostatin was iv or sc injected in Rhesus monkeys, and the rh-endostatin concentration in serum samples was determined by an enzyme immunoassay (EIA) method. The serum drug concentration-time data were analyzed by compartmental analysis using the practical pharmacokinetic program 3p97. RESULTS: Following iv administration at a dose rate of 1.5, 4.5, and 13.5 mg/kg in rhesus monkeys, the concentration-time curves of rh-endostatin were best fitted to a three-compartment open model. AUC(0-infinity) linearly increased with dose, while Cls exhibited no significant difference among different dose groups. The terminal half-lives (lambda3) were 8+/-8, 3.1+/-1.4, and 20+/-14 h, respectively. After sc administration at a dose rate of 1.5 mg/kg, the concentration-time curve was best fitted to a two-compartment open model, with a terminal half-life (T(1/2beta)) of 8+/-3 h. Bioavailability following sc injection was approximately 70%+/-3%. After consecutive iv injection of rh-endostatin at a dose rate of 1.5 mg.kg(-1).d(-1) for 7 d, the AUC(0-24 h) substantially increased from 22+/-13 mg.h.L(-1) (d 1) to 50+/-29 mg.h.L(-1) (d 7), with an accumulation factor of 2.3+/-0.6 (P < 0.05). CONCLUSION: The pharmacokinetic behavior of rh-endostatin in Rhesus monkeys complies with linear kinetics within the examined dose range. It tends to be accumulated in bodies after repeated administration at a dose level of 1.5 mg.kg(-1).d(-1) for more than 7 consecutive days.

[Studies on the pharmacokinetics of lidamycin in mice and dogs using bioassay].

AIM: A bioassay method was established for the determination of active concentrations of lidamycin and studied its pharmacokinetics in mice and dogs. METHODS: Cytotoxicity of lidamycin in vitro was used to determine drug serum concentrations in vivo. RESULTS: Validity of methodology met the requirements of pharmacokinetic study. The concentration-time profile in mice after iv lidamycin of 100, 50 and 10 microg x kg(-1) was best fitted with 2-compartmental model with T1/2alpha and T1/2beta of 0.77-1.8 min and 5.6-7.2 min, respectively. The AUC were 2851.3, 887.8 and 166.4 microg x min x L(-1), respectively and increased with dose nonlinearly. There were similar trends between AUC and the potency of tumor growth inhibition. After iv lidamycin of 12 microg x kg(-1) in dogs, the concentrations of lidamycin decreased rapidly and the AUC was 16 microg x min x L(-1), which were lower and quicker than those in mice. The levels in serum after second administration at day 15, were lower than those of the first. CONCLUSION: Active concentrations and pharmacokinetics of lidamycin were obtained by bioassay method successfully. There are species differences and single and multi-dosing differences in the pharmacokinetics of lidamycin.

Detection and quantitation of PS20, a phosphorothioate oligodeoxynucleotides in monkey plasma.

AIM: To establish the method for quantitation of the phosphorothioate oligodeoxynucleotides (S-ODNs) in plasma. METHODS: Two solid-phase extraction columns combined with a strong anion-exchange column were utilized to remove proteins and lipids in plasma, and the salts were removed by a reverse-phase column followed by dialysis with a 2500 Da-cutoff membrane. The concentration of the tested S-ODNs, PS20, and its metabolites extracted from the plasma were determined by the method of non-gel sieving capillary electrophoresis (NGCE) with diode array detection in the presence of internal standard (IS). RESULTS: The method was with good base number specificity. Relative standard deviation % of both intra and inter assay were all less than 10 %, and the total mean recovery was about 91 %. The methodology was successfully used to determine the PK behavior of an anti-tumor antisense S-ODNs in monkeys and identify the metabolites with single base difference. CONCLUSION: The combined method of solid-phase extraction and NGCE could be used to study the pharmacokinetics of S-ODNs, and the main parameters of the methodology met the requirement of PK study.

Optimization of antisense drug design against conservative local motif in simulant secondary structures of HER-2 mRNA and QSAR analysis.

AIM: To study the role of mRNA secondary structure stability in antisense drug design and obtain better antisense candidates against neu/HER-2/erbB-2 mRNA than previous report. METHODS: Program RNAstructure was utilized to simulate the secondary structures of HER-2 mRNA. Then 21 antisense phosphorothioate oligodeoxynucleotides (S-ODN) targeting different parts of secondary structural motif were designed. HA4 was set as positive control. Mean 50 % inhibitory effects (IC(50)) of S-ODN on proliferations of SK-BR-3 breast cancer cells were evaluated. The expression of target mRNA was detected by RT-PCR. The multiple regression and quantitative structure-activity relationship (QSAR) analysis was preformed by SPSS software. RESULTS: One optimal and two suboptimal secondary structures of target mRNA were obtained. Nine out of 11 S-ODN against completely conservative local motif (LM) (conservative among all simulant secondary structures) got lower or similar IC(50) values compared with HA4. On the other hand, 2 out of 3 S-ODN against relatively conservative LM (conservative between any two simulant secondary structures) got lower or similar IC(50) values compared with HA4. Only 2 out of 5 S-ODN targeting variable LM (variable among different predicted secondary structures) had acceptable activities. Average IC(50) of S-ODN against completely conservative LM was significantly lower than that of S-ODN against diverse LM. QSAR analysis suggested that stability, base number of bulge loops, and target free energies Delta GoT were statistically significant. In the multiple regression, R was 0.967, P=0.005. CONCLUSION: Antisense drug design against conservative LM was helpful for improving the positive rate. Several S-ODN candidates better than positive control were screened.

Antisense candidates against protein kinase C-alpha designed based on phylogenesis and simulant structure of mRNA.

AIM: To optimize the antisense drug design by the combined method of phylogenetic analysis and secondary structure prediction and to get ideal candidates. METHODS: The phylogenetic analysis and the secondary structure simulation were performed by computer. Oligodeoxynucleotides (ODN) were designed against the full-conserved blocks with low local reaction free energy of protein kinase C (PKC)-alpha mRNA. The in vitro effects of ODN were evaluated by human A549 lung carcinoma cells and mouse B16-BL6 melanoma cells, the expression of target mRNA was detected by in situ hybridization and RT-PCR. The in vivo effects of ODN were also evaluated by models of A549 xenografts in nude mice and B16 melanoma in mice. RESULTS: Three ODN had significantly lower IC50 values than that of ISIS3521, the positive control, on A549 cells in vitro. Five ODN inhibited the growth of B16-BL6 cells with IC50 <100 nmol/L, while IC50 of ISIS3521 was >200 nmol/L. In situ hybridization and RT-PCR showed that the best candidate AP1261 inhibited the expression of PKC-alpha at mRNA level in a dose-dependent manner. AP1261 inhibited the growth of A549 and B16 tumors in vivo at 0.005-0.5 mg.kg(-1).d(-1). The inhibitory rate of AP1261 on A549 tumors was greater than that of ISIS3521 at the same dose. ISIS3521 did not affect the growth of B16 tumors. CONCLUSION: AP1261 may be of value as an antitumor agent or adjuvant and the combined method of phylogenetic analysis and secondary structure prediction is a potential helpful tool for antisense drug design.

Pharmacokinetics and partial thromboplastin time after intravenous recombinant hirudin variant-2 in rhesus monkeys.

AIM: To study the pharmacokinetics (PK) and changes of kaolin partial thromboplastin time (KPTT) following single or multiple (7 d) dosing of a novel recombinant hirudin variant-2 (rHV-2) via the route of iv bolus injection (50 % of the total dose) plus infusion (the remained 50 % of the dose) in rhesus monkeys. METHODS: A crossover design was applied to research the PK and KPTT profiles of rHV-2 after single (with total dose at 1, 3, and 6 mg/kg, respectively) and multiple dosing (3 mg/kg). An enzyme-linked immunosorbent assay (ELISA) method was utilized to determine the level of rHV-2 in plasma. RESULTS: The concentration profiles of rHV-2 during or after administration were dependent both on the loading dose and the infusion rate. Mean Cmax after bolus in three single dose groups were 2.90, 9.78, and 15.68 mg/L, respectively. Infusions at rate of 8.35, 25, and 50 g/kg/h in 1 h resulted in steady-state levels of 0.73-0.86, 1.94-2.04, and 5.41-5.59 mg/L, respectively. The plasma rHV-2 levels during or after administration among doses were significantly different at most of the time points. Area under concentration-time curve (AUC) increased linearly with dose but systemic clearances were similar among different groups. KPTT was significantly prolonged (compared with baseline) at all dose levels, and trended to increase with dose. CONCLUSION: Both the loading dose and the infusion rate are very important for controlling the rHV-2 level, and the data may be helpful for optimizing dosage-regimen in clinical trials.

[Metabolism, Distribution and Excretion of Recombinant Human Thrombopoietin in Mice]

The metabolism, distribution and excretion profiles of recombinant human thrombopoietin (rhTPO) in mice were studied by means of (125)I-labeled rhTPO ((125)I-rhTPO) combined with size exclusive high performance liquid chromatography (SHPLC) or trichloroacetic acid (TCA) precipitation analysis. (125)I-rhTPO was prepared by iodogen method. Purification was performed on Sephacryl S-200 HR gel. Radioactive-purity of (125)I-rhTPO identified by SHPLC was (96.9 +/- 1.5)% (n = 3). The proliferation effect of TPO dependent cell line (TD-3) and the increase of peripheral platelet counts in mouse by (125)I-rhTPO demonstrated that (125)I-labeled protein maintained the biological activities of TPO both in vitro and in vivo. SHPLC analysis of serum and urine samples taken after sc 1 micro g/mouse (345 kBq/mouse) of (125)I-rhTPO revealed that there were two lower molecular weight (125)I-degradation metabolites ((125)I-MI and (125)I-MII) other than parent molecule. (125)I-MI was mainly found in urine, and (125)I-MII was detected both in serum and in urine. The maximal concentration of (125)I-rhTPO was reached at 2 hours after injection. The terminal half-life was 10.8 hours, which was much longer than those of other peptides. TCA precipitable radioactivity in tissue showed that the radioactivity in bone marrow was rather high. The highest level was found in urinary system. Levels in adrenals, lymph nodes, and fat were near to that in serum. Lowest was found in brain. The main excretion route was urinary system and (98 +/- 5.6)% of (125)I-rhTPO was excreted within 72 hours after dosing.