Impact of targeting transforming growth factor β-2 with antisense OT-101 on the cytokine and chemokine profile in patients with advanced pancreatic cancer

Background

Overexpression of the cytokine – transforming growth factor-beta 2 (TGF-β2) – has been implicated in the malignant progression of pancreatic cancer (PAC). OT-101 (trabedersen) is an antisense oligodeoxynucleotide designed to target the human TGF-β2 mRNA. In a Phase I/II study, OT-101 treatment with subsequent chemotherapy was characterized by outstanding overall survival (OS) in patients with PAC.

Objective

This study sought to identify 1) co-regulated sets of cyto-/chemokines; 2) potential mechanisms that link TGF-β receptor type 2 receptor inhibition that may result in the induction of a cytokine storm; and 3) predictive biomarkers for OS outcome in OT-101-treated patients with PAC.

Materials and methods

Plasma levels of 31 cyto-/chemokines were tracked over three cycles of OT-101 therapy (140 mg/m²/day) in 12 PAC patients. Samples were acquired before onset of OT-101 therapy and at eight selected time points during therapy. A mixed ANCOVA model was developed for 19 cyto-/chemokines with median expression >1 following OT-101 therapy. Regression and hierarchical clustering analyses were performed to identify correlated expressions in each patient across cyto-/chemokines or in each cyto-/chemokine across patients. Plasma cyto-/chemokine levels were compared with OS with and without subsequent chemotherapy.

Results

Three highly correlated subsets of cyto-/chemokines (Cluster 1: EGF, MIP-1α, MIP-1β; Cluster 2: FGF-2, MIG, IP-10, IL-15, IFN-α, IL-12; and Cluster 3: HGF, IL-6, IL-8) were identified following OT-101 therapy. Suppression of TGF-β signaling by OT-101 led to upregulation of IL-8, IL-15, IP-10, and HGF. Protein–protein interaction networks constructed using STRING10 algorithm identified a relationship between IL-8, IL-15, and TGF-β receptor type 2 inhibition. The mixed analysis of covariance model that examined the levels of 19 cyto-/chemokines with OS as the covariate at each of the time points resulted in IL-8 and IL-15 exhibiting a significant association with OS during Cycle 1 of therapy. In the whole-blood culture model, the cytokines with the most pronounced increase after OT-101 treatment were IL-1β, IL-8, and MCP-1.

Conclusion

No consistent responses in cyto-/chemokine levels were observed due to OT-101 treatment. Levels of IL-8 and IL-15 during Cycle 1 were positively associated with OS across 12 patients with PAC and served as potential biomarkers for treatment outcome following OT-101 therapy.

Abstract 4902: Celecoxib fixed-dose combination: antitumor activity on tumor growth and metastasis

Background: Breast cancer and melanoma are associated with a high rate of lymphatic and hematogenous metastasis which results in high rate of cancer mortality. Inflammation and hypertension (HTN) have recently emerged as causal factors for tumor progression and anti-hypertensive agents have been shown to reduce inflammation and suppress tumor growth and metastasis. Cyclooxygenase-2 (COX-2) is upregulated in most human tumors and is a potent inducer of cancer-associated inflammation that promotes tumor angiogenesis and lymphangiogenesis. This study evaluated a novel combination of a selective COX-2 inhibitor with three antihypertensive drugs to suppress tumor growth and metastasis in preclinical xenograft models.

Methods: Three anti-hypertensive drugs were evaluated in this study: i) Lisinopril [LIS], an inhibitor of angiotensin-1 converting enzyme (ACE); ii) Olmesartan medoxomil (OLM), an angiotensin II receptor blocker (ARB); and iii) Hydrochlorothiazide (HCTZ), a thiazide diuretic along with Celecoxib [CEL], a selective COX-2 inhibitor. CEL, LIS, OLM, and HCTZ were evaluated either alone or in combination for tumor growth suppression and metastatic spread in an orthotopic xenograft model of triple-negative inflammatory breast cancer/SUM149 and subcutaneous xenograft models of melanoma/MDA-MB-435, glioblastoma/U87-MG, and triple-negative SUM159. Luciferase-tagged SUM149 and MDA-MB-435 cell lines were used to determine the incidence and the burden of locoregional and systemic spread. Mice were monitored twice a week for 9-16 weeks for percent weight loss, tumor volume and survival outcome. Metastatic tumor burden and incidence was measured as luciferase expression in lymph nodes and lungs and normalized to total protein.

Results: In the SUM149 model, the saline treated control had an average tumor burden of 17.6 ± 8.6 x104 RLU per mg of protein in the ipsilateral lymph nodes (ILN). Two groups, OLM alone and CEL + OLM, had a statistically significant decrease in ILN burden. Olmesartan alone had a 7.1-fold decrease in tumor burden with an average of 2.4 ± 0.6 x104 RLU per mg of protein (p-value = 0.01 by Mann-Whitney test). Similar trend was observed for LIS, but not for HCTZ. In the subcutaneous model, synergistic antitumor activity was observed with OLM (p = 0.026) at low dose but not with LIS and CEL (p = ns). At high dose, LIS, OLM, and CEL showed significant inhibition of tumor growth but no synergy. When these agents were combined with Paclitaxel in the SUM159 model, there was only additive effect. HCTZ, an antihypertensive diuretic which has no direct impact on the vascular wall had no effect on tumor growth.

Conclusion: These preclinical data strongly suggest a hitherto unappreciated role of ACE/ARB in tumor growth control and support the further exploration of fixed-dose combinations of CEL with ACE/ARB in cancer, especially inflammatory breast cancer.

Citation Format: Cynthia Lee, Osmond J. D'Cruz, Kevin Ng, Vuong Trieu. Celecoxib fixed-dose combination: antitumor activity on tumor growth and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4902. doi:10.1158/1538-7445.AM2017-4902

Mucosal Toxicity Studies of a Gel Formulation of Native Pokeweed Antiviral Protein

Pokeweed antiviral protein (PAP), a 29-kDa plant-derived protein isolated from Phytolacca americana, is a promising nonspermicidal broad-spectrum antiviral microbicide. This study evaluated the mucosal toxicity potential of native PAP in the in vivo rabbit vaginal irritation model as well as the in vitro reconstituted human vaginal epithelial tissue model. Twenty-two New Zealand white rabbits in 4 subgroups were exposed intravaginally to a gel with and without 0.01, 0.1, or 1.0% native PAP for 10 consecutive days. The dose of PAP used represented nearly 200- to 20,000 times its in vitro anti-HIV IC50 value. Animals were euthanized on day 11 and vaginal tissues were evaluated for histologic and immunohistochemical evidence of mucosal toxicity, cellular inflammation, and hyperplasia. Blood was analyzed for changes in hematology and clinical chemistry profiles. Reconstituted human vaginal epithelial tissue grown on membrane filters was exposed to 0.1, 0.1, or 1.0% native PAP in medium or topically via a gel for 24 hours and tissue damage was evaluated by histological assessment. In the in vivo rabbit vaginal irritation model, half of all PAP-treated rabbits (8/16) exhibited an acceptable range of vaginal mucosal irritation (total score <8 out of a possible 16), whereas nearly a third of PAP-treated rabbits (5/16) developed moderate to marked vaginal mucosal irritation (total score >11). However, no treatment-related adverse effects were seen in hematological or clinical chemistry measurements. Furthermore, in vitro exposure of a 3-dimensional human vaginal tissue grown on polycarbonate membrane filters to identical concentrations of PAP either added to culture medium or applied topically via gel formulation did not result in direct toxicity as determined by histologic evaluation. These findings indicate careful monitoring of vaginal irritation will be required in the clinical development of PAP as a nonspermicidal microbicide.

A Study of the Potential of the Pig as a Model for the Vaginal Irritancy of Benzalkonium Chloride in Comparison to the Nonirritant Microbicide PHI-443 and the Spermicide Vanadocene Dithiocarbamate

A porcine model was established to test the mucosal toxicity potential of a thiophene thiourea (PHI-443)-based anti-HIV microbicide and a vanadocene-based spermicide, vanadocene dithiocarbamate (VDDTC) in comparison to benzalkonium chloride (BZK). Nine domestic pigs (Duroc) in nonestrus stage received a single intravaginal application of 2% BZK, 2% PHI-443, or 0.1% VDDTC-containing gel. At various times after gel application, cell differentials and levels of inflammatory cytokines (IL-1 β, IL-4, IL-6, IL-8, IL-10, IL-18, IFN- γ, and TNF- α) in cervicovaginal lavage (CVL) fluid were monitored by flow cytometry and ELISA, respectively. Eight pigs were exposed intravaginally to a gel with and without BZK or VDDTC for 4 consecutive days and vaginal tissues were scored histologically for inflammation using a new scoring system. Only CVL fluid from pigs exposed to BZK showed a significant increase of IL-1 β, IL-8, and also IL-18 production when compared to the controls, PHI-443 or VDDTC-treated groups. Maximum levels of BZK-induced IL-1 β (100-fold), IL-8 (2,500-fold), IL-18 (80-fold), and IFN- γ(10-fold) were found at 24 hours. In the in vivo porcine vaginal irritation model, increased levels of vaginal IL-1 β, IL-8, and IL-18 were associated with histological changes consistent with vaginal inflammation. These results demonstrate that key cervicovaginal inflammatory cytokines are useful in vivo biomarkers for predicting the mucosal toxicity potential of vaginal products in the physiologically relevant and sensitive porcine model.

Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia

Patients with B cell precursor acute lymphoblastic leukemia (BPL) respond well to chemotherapy at initial diagnosis; however, therapeutic options are limited for individuals with BPL who relapse. Almost all BPL cells express CD19, and we recently cloned the gene encoding a natural ligand of the human CD19 receptor (CD19L). We hypothesized that fusion of CD19L to the soluble extracellular domain of proapoptotic TNF-related apoptosis-inducing ligand (sTRAIL) would markedly enhance the potency of sTRAIL and specifically induce BPL cell apoptosis due to membrane anchoring of sTRAIL and simultaneous activation of the CD19 and TRAIL receptor (TRAIL-R) apoptosis signaling pathways. Here, we demonstrate that recombinant human CD19L-sTRAIL was substantially more potent than sTRAIL and induced apoptosis in primary leukemia cells taken directly from BPL patients. CD19L-sTRAIL effectively targeted and eliminated in vivo clonogenic BPL xenograft cells, even at femtomolar-picomolar concentrations. In mice, CD19L-sTRAIL exhibited a more favorable pharmacokinetic (PK) profile than sTRAIL and was nontoxic at doses ranging from 32 fmol/kg to 3.2 pmol/kg. CD19L-sTRAIL showed potent in vivo antileukemic activity in NOD/SCID mouse xenograft models of relapsed and chemotherapy-resistant BPL at nontoxic fmol/kg dose levels. Together, these results suggest that recombinant human CD19L-sTRAIL has clinical potential as a biotherapeutic agent against BPL.

Vaginal microbicides and their delivery platforms

INTRODUCTION

HIV type 1 infection, despite having fallen by one-third over the past decade, remains a global health concern affecting millions of individuals worldwide. A focal point in contemporary research aimed at global HIV prevention has been the development of safe and efficacious coitally dependent and coitally independent anti-HIV microbicides to curb heterosexual HIV transmission. Despite extensive research efforts to develop novel vaginal antiretroviral (ARV) formulations and intravaginal ring delivery systems, the clinical advancement of microbicides with improved safety, efficacy and tolerability has significantly lagged behind.

AREAS COVERED

This review focuses on the current status of both coitally dependent and coitally independent delivery platforms designed to increase user acceptability and clinical effectiveness of anti-HIV microbicides. The clinical failure of several vaginal microbicide candidates has propelled the field to mechanism-based ARV candidates that act more specifically on viral receptors, viral enzymes and host proteins. Consequently, improved vaginal microbicide delivery strategies that achieve uniform drug distribution with enhanced solubility, sustained drug release, improved product adherence with reduced dosing frequency and lack of effect on the vaginal mucosa and microbiota are being sought.

EXPERT OPINION

Clinical success with vaginal microbicides may best be achieved through the combined effects of ARV compounds that exhibit different mechanisms of action with potent activity against multidrug-resistant HIV and efficacious delivery systems.

Protein kinase inhibitors against malignant lymphoma

INTRODUCTION

Tyrosine kinases (TKs) are intimately involved in multiple signal transduction pathways regulating survival, activation, proliferation and differentiation of lymphoid cells. Deregulation or overexpression of specific oncogenic TKs is implicated in maintaining the malignant phenotype in B-lineage lymphoid malignancies. Several novel targeted TK inhibitors (TKIs) have recently emerged as active in the treatment of relapsed or refractory B-cell lymphomas that inhibit critical signaling pathways, promote apoptotic mechanisms or modulate the tumor microenvironment.

AREAS COVERED

In this review, the authors summarize the clinical outcomes of newer TKIs in various B-cell lymphomas from published and ongoing clinical studies and abstracts from major cancer and hematology conferences.

EXPERT OPINION

Multiple clinical trials have demonstrated that robust antitumor activity can be obtained with TKIs directed toward specific oncogenic TKs that are genetically deregulated in various subtypes of B-cell lymphomas. Clinical success of targeting TKIs is dependent upon on identifying reliable molecular and clinical markers associated with select cohorts of patients. Further understanding of the signaling pathways should stimulate the identification of novel molecular targets and expand the development of new therapeutic options and individualized therapies.

Novel Bruton's tyrosine kinase inhibitors currently in development

Bruton’s tyrosine kinase (Btk) is intimately involved in multiple signal-transduction pathways regulating survival, activation, proliferation, and differentiation of B-lineage lymphoid cells. Btk is overexpressed and constitutively active in several B-lineage lymphoid malignancies. Btk has emerged as a new antiapoptotic molecular target for treatment of B-lineage leukemias and lymphomas. Preclinical and early clinical results indicate that Btk inhibitors may be useful in the treatment of leukemias and lymphomas.

Novel tight binding PETT, HEPT and DABO-based non-nucleoside inhibitors of HIV-1 reverse transcriptase

Non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are a key component of effective combination antiretroviral therapies for HIV/AIDS. NNRTIs despite their chemical diversity, bind to a common allosteric site of HIV-1 RT, the primary target for anti-AIDS chemotherapy, and noncompetitively inhibit DNA polymerization. NNRTIs currently in clinical use have a low genetic barrier to resistance and therefore, the need for novel NNRTIs active against drug-resistant mutants selected by current therapies is of paramount importance. We describe the chemistry and biological evaluation of highly potent novel phenethylthiazolylthiourea (PETT), 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) and dihydroalkoxybenzyloxopyrimidine (DABO) derivatives targeting the hydrophobic binding pocket of HIV-1 RT. These NNRTIs were rationally designed by molecular modeling and docking studies using a novel composite binding pocket that predicted how drug-resistant mutations would change the RT binding pocket shape, volume, and chemical make-up and how these changes could affect NNRTI binding. Several ligand derivatization sites were identified for docked NNRTIs that fit the composite binding pocket. The best fit was determined by calculating an inhibition constant (Ludi Ki) of the docked compound for the composite binding pocket. Compounds with a Ludi Ki of <1 microM were identified as the most promising tight binding NNRTIs. These NNRTIs displayed high selective indices with robust anti-HIV-1 activity against the wild-type and drug-resistant isolates carrying multiple RT gene mutations. The high rate of treatment failure due to the emergence of drug resistance mutations makes the discovery of broad-spectrum PETT, HEPT and DABO-based NNRTIs useful as a component of effective combination regimens.

Evaluation of local tolerance of the antiretroviral spermicide (WHI-07)-loaded gel-microemulsion in the porcine female reproductive tract

The local tolerance of the antiretroviral spermicide, WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate)-loaded gel-microemulsion was evaluated in a physiologically relevant and sensitive porcine model. Gilts (Duroc) in nonestrus stages of the reproductive cycle received either a single or a daily intravaginal application of 2.0% WHI-07 via a gel-microemulsion for 6 days. Cervicovaginal lavage (CVL) fluid was obtained for up to 72 h after a single exposure and the cellular profile and levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) were quantitated by flow cytometry and chemiluminescence-based multiplex immunoassay, respectively. The reproductive tract (vagina, cervix, uteri and Fallopian tubes) harvested on day 7 was scored histologically for evidence of mucosal irritation using a new scoring criterion for ten histological endpoints that reflect pathological changes in the epithelial/ subepithelial and vascular/perivascular compartments. When compared with irritant reactions caused by the detergent-type spermicide, benzalkonium chloride (BZK), the scatter profile of CVL immune cells and basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in CVL fluid were unaffected by intravaginal exposure to 2% WHI-07. Unlike BZK, endpoint histology of the proximal and distal regions of the reproductive tract from gilts treated with 2.0% WHI-07 via gel-microemulsion for 6 days did not result in mucosal irritation or alteration in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues and underlying/surrounding muscles. Based on surrogate markers for inflammation, leukocyte profile and histologic data for local tolerance, repeated intravaginal administration of WHI-07 via gel-microemulsion as a prophylactic contraceptive is unlikely to cause vaginal irritation.

Preclinical evaluation of a dual-acting microbicidal prodrug WHI-07 in combination with vanadocene dithiocarbamate in the female reproductive tract of rabbit, pig, and cat

The mucosal safety of the combination antiretroviral spermicide,WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] and vanadocene dithiocarbamate (VDDTC), was evaluated in 3 different animal models. Twenty-seven NZW rabbits in four subgroups were exposed intravaginally to a gel-microemulsion (GM) with and without three dose levels of WHI-07 plus VDDTC (0.5+0.06%, 1.0+0.12% and 2.0+0.25%) or 4% nonoxynol-9 (N-9; Conceptrol) for 14 consecutive days. Ten nonestrus gilts (Duroc) in three subgroups received either a single or daily intravaginal application of GM with and without 2.0% WHI-07 plus 0.25% VDDTC or 2.0% benzalkonium chloride (BZK)-containing gel for 6 and 4 consecutive days, respectively. Five cats received a single intravaginal application of GM incorporating 2.0% WHI-07 plus 0.25% VDDTC. Genital tract histopathology was performed in the pig and rabbit at the end of dosing period but after 18 weeks post-dosing in the cat. Porcine cervicovaginal lavage (CVL) fluid was obtained for up to 72 hours after a single exposure and changes in the levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma, and TNF-alpha) were quantitated by a multiplexed chemiluminescence-based immunoassay. Rabbit vaginal tissues were evaluated for localized cellular inflammation and in situ apoptosis by immunohistochemical staining for CD45, nuclear factor (NF)-kappa B, and terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) using confocal laser scanning microscopy (CLSM), respectively. Vanadium content in selected organs and body fluids from rabbits and pigs was determined by atomic absorption spectroscopy. When compared with 4% N-9 (total irritation score 13-14 out of a possible 16), none of the rabbits given WHI-07 plus VDDTC intravaginally, developed histological alterations such as epithelial erosion, edema, leukocyte influx or vascular congestion characteristic of inflammation (total irritation score 4-6). CD45 and NF-kappa B immunoreactivity was limited to cells within the vascular lumen of both control and WHI-07 plus VDDTC-treated vaginal tissues. TUNEL assay revealed lack of increased apoptotic cells in vaginal mucosa exposed to increasing concentrations of WHI-07 plus VDDTC. Basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in porcine CVL were unaffected by intravaginal exposure to WHI-07 plus VDDTC when compared with BZK used as a positive control. Endpoint histology of the reproductive tract from cats and pigs after a single or repeated intravaginal exposure to WHI-07 plus VDDTC, respectively, revealed lack of irritation/inflammation in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues, and underlying/surrounding muscles. Vanadium was not preferentially incorporated into rabbit or porcine tissues and body fluids at levels above 1 microg/g. Based on comparative histologic data and surrogate markers for inflammation, repeated intravaginal administration of WHI-07 plus VDDTC via a gel-microemulsion did not result in vaginal irritation, mucosal toxicity, or systemic absorption of vanadium. Therefore, the combined use of WHI-07 and VDDTC via gel-microemulsion appears safe for topical use as a prophylactic anti-HIV microbicide.

Microbicides for multidrug-resistant and multitropic HIV-1

The most common mode of acquiring HIV-1 is via sexual transmission across the genital mucosa. Topical microbicides are a promising prevention strategy for the protection against HIV infection and may ultimately have an impact on the global AIDS pandemic. The effectiveness of a microbicide to prevent HIV-1 transmission will depend on the evolutionary and genital transmission dynamics of the viral subtypes, and sexual behavioral characteristics. Contemporary antiretroviral therapy has led to virological failure as a result of HIV-1 reverse transcriptase gene mutations. The transmission of these multidrug-resistant HIV-1 variants, and the superinfection with the same or distinct HIV-1 subtypes and recombination is a formidable hindrance inherent to global microbicide development. Consequently, mechanism-based microbicides targeting both the cell-free and cell-associated HIV-1 variants and subtypes can be expected to have superior clinical efficacy and safety profiles compared with polymeric anionic microbicides. This review describes the discovery of potent anti-HIV-1 agents against multidrug-resistant and multitropic HIV-1 variants with implications for global microbicide development. Stampidine and thiourea non-nucleoside reverse transcriptase inhibitors (NNRTIs) have demonstrated highly potent activity against clinically relevant multidrug-resistant and recombinant HIV-1 isolates spanning different subtypes across several continents. Extensive preclinical studies have shown that stampidine and a candidate thiourea NNRTI (HI-443) have clinical potential as a safe combination microbicide to inhibit, prevent or treat mucosal HIV-1 infections.

Targeting mast cells in endometriosis with janus kinase 3 inhibitor, JANEX-1

Endometriosis (EMS) is a chronic inflammatory disease of multifactorial etiology characterized by implantation and growth of endometrial glands and stroma outside the uterine cavity. EMS is a significant public health issue as it affects 15-20% of women in their reproductive age. Clinical symptoms may include pelvic pain, dysmenorrhea, dyspareunia, pelvic/abdominal masses, and infertility. Symptomatic treatments such as surgical resection and/or hormonal suppression of ovarian function and analgesics are not as effective as desired. Consequently, there is an enormous unmet need to develop effective medical therapy capable of preventing the occurrence and recurrence of EMS without undesirable side-effects. EMS-associated intra-abdominal bleeding episodes, local inflammation, adhesions, and i.p. immunologic dysfunction leads to pelvic nociception and pelvic pain. Increasing evidence supports the involvement of allergic-type inflammation in EMS. Invasion of mast cells, degranulation, and proliferation of interstitial component are observed in endometriotic lesions. Presence of activated and degranulating mast cells within the nerve structures can contribute to the development of pain and hyperalgesia by direct effects on primary nociceptive neurons. Therefore, treatments targeting endometrial mast cells may prove effective in preventing or alleviating EMS-associated symptoms. The Janus kinase 3 (JAK3) is abundantly expressed in mast cells and is required for the full expression of high-affinity IgE receptor-mediated mast cell inflammatory sequelae. JANEX-1/WHI-P131 is a rationally designed novel JAK3 inhibitor with potent anti-inflammatory activity in several cellular and in vivo animal models of inflammation, including mouse models of peritonitis, colitis, cellulitis, sunburn, and airway inflammation with favorable toxicity and pharmacokinetic profile. We hypothesize that JAK3 inhibitors, especially JANEX-1, may prove useful to prevent or alleviate the symptoms of EMS.

Mucosal safety of PHI-443 and stampidine as a combination microbicide to prevent genital transmission of HIV-1

OBJECTIVE

To investigate the in vitro and in vivo mucosal safety of a nonnucleoside reverse transcriptase (RT) inhibitor (PHI-443) and a nucleoside analogue RT inhibitor (stampidine)-based anti-HIV microbicide either alone or in combination.

DESIGN

In vitro and in vivo studies using three-dimensional vaginal epithelia integrating Langerhans cells and 16 New Zealand White rabbits, respectively.

SETTING

Research laboratory.

INTERVENTION(S)

Rabbits in groups of four were exposed intravaginally to a gel with and without 1% PHI-443, 1% stampidine, or 1% PHI-443 plus 1% stampidine for 14 days. Cytokine/chemokine release by three-dimensional co-cultures in the presence and absence of PHI-443 or stampidine.

MAIN OUTCOME MEASURES(S)

Histologic scoring of vaginal tissue for mucosal toxicity at 24 hours after dosing. Simultaneous evaluation of levels of 10 cytokines (granulocyte-macrophage colony-stimulating factor, interleukin-1 alpha, interleukin-13, macrophage inflammatory protein-1 beta, granulocyte colony-stimulating factor, interleukin-18, tumor necrosis factor-alpha, interleukin-6, interleukin-1 beta, and interferon-gamma) and 6 chemokines (epithelial neutrophil-activating peptide-78, interleukin-8, monocyte/macrophage chemoattractant protein-1, macrophage inflammatory protein-3 alpha, interferon-inducible protein-10, and regulated upon activation of normal T-cell expressed and secreted) in culture media by a multiplexed chemiluminescence-based immunoassay.

RESULT(S)

In the rabbit model, repeated intravaginal administration of PHI-443 plus stampidine via a gel formulation at concentrations nearly 2,000 and 10,000 times higher than their respective in vitro anti-HIV IC(50) values did not result in vaginal irritation. The levels of proinflammatory cytokines/chemokines secreted by multilayered human genital epithelia integrating Langerhans cells were unaffected by prolonged exposure to PHI-443 or stampidine.

CONCLUSION(S)

The combination of PHI-443 and stampidine was noncytotoxic to vaginal epithelial cells, nonirritating to vaginal mucosa, and did not induce the secretion of proinflammatory cytokines and chemokines by co-cultures of human genital epithelia and Langerhans cells. These attributes are particularly useful for the clinical development of PHI-443 and stampidine as a combination microbicide and as a prophylactic anti-HIV agent to curb genital transmission of HIV-1 by semen.

Limitations of the Human-PBL-SCID Mouse Model for Vaginal Transmission of HIV-1

PROBLEM

SCID mice reconstituted with human peripheral blood lymphocytes (PBL) are amenable to vaginal transmission of HIV-1. We investigated the effectiveness of this model to establish systemic HIV-1 infection.

METHOD OF STUDY

Eighty progesterone-primed C.B-17 SCID mice were reconstituted with human-PBLs and intravaginally inoculated with CCR5 HIV-1 (BaL or 92BR09) infected human-PBLs in the presence of human semen. After two weeks, viral RNA load in spleen, peritoneal lavage (PL), and serum was quantitated by the nucleic acid sequence-based amplification method.

RESULTS

In five independent experiments, spleen from 8/60 (13.3%), PL from 7/60 (11.6%), and serum from 16/56 (28.5%) mice were positive for BaL HIV-1 infection. Similarly, spleen from 4/20 (20%), PL from 1/20 (5%) and serum from 5/20 (25%) mice vaginally inoculated with 92BR09-infected human-PBLs were positive for HIV-1. A one-sided power analysis using normal approximation revealed that at 5% significance level, the overall response rate need to increase form 0.29 to 0.9 and 80% of the control groups needs to achieve a response rate between 6/10 and 9/10 to make the assay feasible.

CONCLUSION

The incidence of vaginal transmission of CCR5 HIV-1 in the human-PBL-SCID mouse was low and variable, which constitutes a major disadvantage for preclinical evaluation of vaginal microbicides.

Influence of long-term stability conditions on microbicidal nucleoside prodrug (WHI-07)-loaded gel-microemulsion

The objective of this study was to evaluate the long-term stability of the antiretroviral spermicide WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate) in a polymer-based microemulsion. The recovery and stability of WHI-07 in gel-microemulsion was examined by a validated high-performance liquid chromatography (HPLC) method. The stability was examined over a period of 24 weeks at 3 controlled temperatures (4 degrees C, 25 degrees C, and 40 degrees C). The recovery of the prodrug from 0.5% to 2.0% WHI-07-loaded gel-microemulsion was 99.8%. HPLC analysis revealed that a 2% WHI-07-loaded gel-microemulsion stored at room temperature and cold temperatures for 24 weeks retained >90% of the prodrug, whereas those stored at 40 degrees C maintained 90% of initial WHI-07 for at least 10 weeks. The observed stability of WHI-07 in gel-microemulsion is of great importance for its widespread utility in various climatological conditions.

Vaginal contraceptive activity of a chelated vanadocene

Bis(cyclopentadienyl) complexes of vanadium (IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. This study sought to determine the vaginal contraceptive activity of vanadocene dithiocarbamate (VDDTC), a stable vanadocene (IV)-chelated complex, using the standard rabbit model as well as the domestic pig as a physiologically relevant animal model for contraception. In experiment I, ovulating New Zealand White does in subgroups of eight were artificially inseminated (AI) with semen mixed with VDDTC (0.01-1 mM) or vehicle. In experiment II, ovulating does in subgroups of 18 were AI at 5 and 60 min after intravaginal application of a gel with and without 0.1% VDDTC or 2% nonoxynol-9 (N-9) (Gynol II, Ortho Pharmaceutical, Raritan, NJ), and allowed to complete term pregnancy. In experiment III, seven sexually mature Duroc gilts in standing estrus were AI with and without intravaginal application of 0.1% VDDTC gel microemulsion. Exposure of rabbit semen to VDDTC at the time of artificial insemination resulted in a dose-dependent reduction in fertility. Exposure of semen to 1 mM VDDTC led to complete inhibition of fertility as assessed by the number of embryos (control 49/94 vs. VDDTC-treated 0/117, p<.0001) or the percent embryos (52% vs. 0%, respectively) based on number of embryos to corpora lutea. Intravaginal administration of 0.1% VDDTC gel microemulsion or Gynol II prior to artificial insemination significantly inhibited term pregnancy rates (88% and 62% inhibition, respectively) when compared to control gel alone. Vanadocene dithiocarbamate gel microemulsion provided 80% inhibition of fertility even when insemination was delayed until 60 min after intravaginal application of VDDTC gel microemulsion. Rabbits that delivered litters despite intravaginal exposure of semen to VDDTC via gel microemulsion had healthy offsprings with no apparent perinatal repercussions. In domestic pigs, intravaginal applications of 0.1% VDDTC gel microemulsion prior to artificial insemination led to complete inhibition of fertility as assessed by the number of embryos (control 29/52 vs. VDDTC-treated 0/44, p<.0001) or the percent embryos (56% vs. 0%, respectively) based on the number of embryos to corpora lutea. These results suggest that VDDTC is a potent contraceptive agent in vivo. Intravaginal use of VDDTC via a gel microemulsion has clinical potential as a safe alternative to currently used detergent-type contraceptives.

Novel Broad-Spectrum Thiourea Non-Nucleoside Inhibitors for the Prevention of Mucosal HIV Transmission

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTI) are an integral part of combination therapy comprising three classes of antiretroviral drugs for the management of HIV/AIDS. NNRTIs are chemically diverse compounds that bind to a common allosteric site of HIV-1 RT and noncompetitively inhibit DNA polymerization. Resistance to NNRTIs arises rapidly upon drug treatment and results from mutation of the amino acids lining the HIV-1 RT binding pocket. Nevertheless, rationally designed NNRTIs deduced from changes in binding pocket size, shape, and residue character that result from clinically observed NNRTI resistance mutations exhibit broad-spectrum anti-HIV-1 activity. Notably, membrane permeable tight binding NNRTIs have utility as topical microbicides since they are capable of blocking cell-free and cell-associated mucosal HIV-1 infection without metabolic activation. This review summarizes the discovery of highly potent tight binding phenethyl-thiazolyl-thiourea (PETT) derivatives targeting the NNI binding pocket of HIV-1 RT. These NNRTIs were rationally designed by molecular docking using a composite binding pocket constructed by superimposing the crystal structure coordinate data of several NNI/RT ligand-binding site complexes. Molecular modeling and score functions such as molecular surface area, the buried surface, and binding affinity values were used to analyze how drug-resistant mutations would change the RT binding pocket shape, volume, and chemical make-up of these NNRTIs, and how these changes could affect drug binding. Several ligand derivatization sites were identified for docked compounds that fit the binding pocket. The best fit was determined by calculating an inhibition constant (Ludi Ki) of the docked compound for the composite binding pocket. Compounds with a Ludi Ki of <1 microM were identified as the most promising tight binding NNRTIs. This review highlights novel lipophilic thiourea NNRTIs that display high binding affinity and selective indices with robust anti-HIV-1 activity against the wild type as well as drug-resistant isolates carrying multiple RT gene mutations. The increasing prevalence of drug-escape mutants among recent HIV seroconverters makes the discovery of these broad-spectrum thiourea NNRTIs useful as a component of topical microbicide for the prevention of mucosal HIV transmission.

Developmental safety profile of the anti-HIV agent stampidine in rabbits

Stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) is a novel aryl phosphate derivative of stavudine (STV, d4T, 2',3'-didehydro-3'-deoxythymidine, CAS 3056-17-5) with potent anti-HIV activity. The reproductive and developmental safety profile of STAMP was evaluated in mated New Zealand white rabbits. STAMP did not adversely affect the reproductive health of female rabbits and it lacked teratogenicity or other developmental toxicity in their progeny.

Dawn of non-nucleoside inhibitor-based anti-HIV microbicides

The emergence of HIV/AIDS as a disease spread through sexual intercourse has prompted the search for safe and effective vaginal and rectal microbicides for curbing mucosal viral transmission via semen. Since endogenous reverse transcription is implicated in augmenting the sexual transmission of HIV-1 infection, potential microbicides should have the inherent ability to optimally inhibit both wild-type and drug-escape mutants. The non-nucleoside reverse transcriptase inhibitors (NNRTIs), which bind to an allosteric site on RT, are an important arsenal of drugs against HIV-1. The clinical success of NNRTI-based HIV/AIDS therapies has led to extensive structural and molecular modelling studies of enzyme complexes and chemical synthesis of second- and third-generation NNRTIs. Rationally designed NNRTIs deduced from changes in binding pocket size, shape and residue character that result from clinically observed NNRTI resistance-associated mutations exhibit high binding affinity for HIV-1 RT and robust anti-HIV activity against the wild-type and drug-escape mutants without cytotoxicity. Notably, membrane permeable tight binding NNRTIs have the ability to inactivate cell-free as well as cell-associated HIV-1 in semen without metabolic activation. Consequently, NNRTIs currently under development as experimental microbicides include thiourea-PETT (where PETT stands for phenethylthiazolylthiourea) derivatives (PHI-236, PHI-346 and PHI-443), urea-PETT derivatives (MIV-150), oxypyrimidines (S-DABOs), thiocarboxanilides (UC-781) and diarylpyrimidines (TMC-120). Mucoadhesive formulations of these NNRTIs have been studied for safety and efficacy in animal models and some have entered Phase I safety testing in humans. This review focuses on the structural, biological and preclinical studies relevant to the clinical development of these NNRTIs as molecular virucides intended to prevent the sexual transmission of HIV-1.

Discovery of 2,5-dimethoxy-substituted 5-bromopyridyl thiourea (PHI-236) as a potent broad-spectrum anti-human immunodeficiency virus microbicide

The increased risk of heterosexual transmission of human immunodeficiency virus-1 (HIV-1) has prompted the search for safe and effective female-controlled vaginal microbicides. Because endogenous reverse transcription is implicated in augmenting the sexual transmission of HIV-1, potential microbicides should have the inherent ability to optimally inhibit both wild-type and drug-resistant mutant strains of HIV-1. N-[2-(2,5-dimethoxyphenylethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (PHI-236) is a rationally designed non-nucleoside inhibitor of HIV-1 reverse transcriptase (NNRTI) that was deduced from changes in binding pocket size, shape and residue character that result from clinically observed NNRTI resistance mutations. PHI-236 displayed high-binding affinity (Ludi K(i) = 0.07 microM) for HIV-1 RT and robust anti-HIV activity against the wild type (IC50 = <0.001 microM) as well as primary clinical isolates (IC50 = 0.009-0.04 microM) carrying multiple RT gene mutations associated with NRTI and NNRTI resistance. PHI-236 displayed high-selectivity index against human vaginal and cervical epithelial cells and did not affect human sperm functions. In the humanized severe combined immunodeficient mouse model for HIV/acquired immune deficiency syndrome (AIDS), pretreatment of HIV-1 (BaL)-infected human monocytes and semen with PHI-236 prevented the systemic infection via the vaginal route. PHI-236 has particular clinical utility as a non-spermicidal microbicide as well as a prophylactic antiviral agent to inactivate cell-free and cell-associated HIV-1 in semen before assisted reproductive technology procedures.

Conceival, a novel noncontraceptive vaginal vehicle for lipophilic microbicides

The objective of this study was to develop a nontoxic and noncontraceptive vaginal drug delivery vehicle for lipophilic anti-human immunodeficiency virus (HIV) microbicides. Three representative poorly water-soluble novel broad-spectrum anti-HIV microbicides, PHI-113, PHI-346, and PHI-443, were evaluated in 11 different solvent systems. Based on their solubility profiles, a novel nonspermicidal self-emulsifying gel (viz Conceival) composed of pharmaceutical excipients, sorbitol, polyethylene glycol 400, polysorbate 80, microcrystalline cellulose, xanthan gum, and water was optimized. Conceival enhanced the solubility of these poorly water-soluble (<0.001 mg/mL) anti-HIV drugs by at least 150- to 270-fold. Conceival was evaluated in vivo in the New Zealand white rabbit model for the preservation of sperm function based on pregnancy outcome and the potential for vaginal irritation following single and multiple intravaginal applications, respectively. Conceival administered intravaginally immediately prior to artificial insemination with semen had no adverse effects on subsequent reproductive performance, neonatal survival, or pup development when compared with untreated control group. Histologic evaluation of vaginal tissues of rabbits exposed intravaginally to Conceival for 14 consecutive days revealed lack of epithelial, submucosal, and vascular changes at the gel application site (total irritation score <3 out of a possible 16). These findings indicate that Conceival has potential to become a clinically useful, safe noncontraceptive vaginal vehicle for lipophilic microbicides.

Stampidine: a selective oculo-genital microbicide

Adenoviruses (ADVs) are causative agents of severe and extremely contagious ocular and genital infections associated with conjunctivitis, genital ulcers and urethritis. Yet, no functional antiviral compounds are currently available against adenoviral infections. We discovered halogen-substituted phenyl phosphoramidate derivatives of stavudine (STV/d4T) as a new class of dual-function anti-human immunodeficiency virus (HIV) agents with potent and selective anti-ADV activity. The lead compound, stampidine [5'-(4-bromophenyl methoxyalaninylphosphate)-2',3'-didehydro-3'-deoxythymidine], was the most potent non-toxic dual-function antiviral agent. Stampidine displayed remarkable in vitro and in vivo anti-HIV activity against drug-sensitive and drug-resistant HIV strains. Stampidine was non-cytotoxic and nonirritating to mucosal epithelial cells. Several preclinical studies conducted thus far, suggest that stampidine has clinical potential as a dual-function topical agent for the prevention and/or effective treatment of oculo-genital ADV/HIV infections.

Antileukemic activity and cellular metabolism of the aryl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07)

The novel aryl phosphate derivative of bromo-methoxy zidovudine (ZDV/AZT) (compound WHI-07, CAS 213982-96-8) was found to be a potent antileukemic agent against human leukemia, lymphoma, and multiple myeloma cell lines in MTT and clonogenic assays with low micromolar IC50 values. In addition, WHI-07 was antimitotic, leading to cell fusion and developmental arrest in the Zebrafish model of rapid cell proliferation. WHI-07 was cytotoxic to drug-sensitive (NALM-6, MOLT-3, HL-60, P388) and multi-drug resistant (MDR) leukemia cell lines (HL-60/VCR, HL-60/ADR, P388/ ADR). Treatment of leukemia cells with WHI-07 showed rapid and dramatic depletion of all cellular nucleoside diphosphate and triphosphate (NDP/NTP) pools, which would contribute to the overall reduction of nucleic acid synthesis and cell death. WHI-07 was rapidly metabolized to alaninyl ZDV monophosphate (Ala-ZDV-MP), the levels of which inversely correlated with cytotoxic IC50 values of WHI-07. Glutathione was found to mediate the in vitro and in vivo detoxification pathway of WHI-07 to 3'-azidothymidine-5'-p-bromophenylmethoxyalaninyl phosphate and Ala-ZDV-MP, respectively. The proposed intracellular metabolic pathway for WHI-07 involves a thiol-mediated dehalogenation step followed by the paraoxon-sensitive carboxylesterase-mediated reaction leading to the formation of Ala-ZDV-MP as the major intracellular metabolite.

PHI-443: A Novel Noncontraceptive Broad-Spectrum Anti-Human Immunodeficiency Virus Microbicide1

PHI-443 (N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)] thiourea) is a rationally designed novel thiophene thiourea nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent anti-HIV activity against the wild-type and drug-resistant primary clinical human immunodeficiency virus (HIV-1) isolates. This study examined the potential utility of PHI-443 as a nonspermicidal microbicide for prevention of sexual transmission of HIV. Our goal in this study was to test the effects of PHI-443 on in vivo sperm functions under conditions shown to inactivate viruses in human cells. PHI-443 completely prevented the vaginal transmission of a genotypically and phenotypically drug-resistant HIV-1 isolate in the humanized severe combined immunodeficient (Hu-SCID) mouse model of sexually transmitted AIDS. Exposure of human sperm to PHI-443 at doses 30 000 times higher than those that yield effective concentrations against the AIDS virus had no adverse effect on sperm motility, kinematics, cervical mucus penetrability, or the viability of vaginal and cervical epithelial cells. Exposure of rabbit semen to PHI-443 either ex vivo or in vivo had no adverse impact on in vivo fertilizing ability in the rabbit model. Reproductive indices (i.e., pregnancy rate, embryo implantation, and preimplantation losses) were not affected by pretreatment of rabbit semen with PHI-443. Likewise, intravaginal application of 2% PHI-443 via a self-emulsifying gel at the time of artificial insemination resulted in healthy offspring with no apparent peri- or postnatal repercussions. Repeated intravaginal administration of 0.5%- 2% PHI-443 gel was found to be safe in rabbits and lacked systemic absorption. PHI-443 has clinical potential as a prophylactic broad-spectrum anti-HIV microbicide without contraceptive activity.

Antiretroviral spermicide WHI-07 prevents vaginal and rectal transmission of feline immunodeficiency virus in domestic cats

WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] is a novel dual-function aryl phosphate derivative of zidovudine with potent anti-human immunodeficiency virus (HIV) and spermicidal activities. WHI-07 was active against the feline immunodeficiency virus (FIV). This study evaluated whether topical application of WHI-07 as a single agent and in combination with an organometallic vanadium complex, vanadocene dithiocarbamate (VDDTC), via a nontoxic gel microemulsion can block vaginal as well as rectal transmission of feline AIDS (FAIDS) by chronically FIV-infected feline T cells in the natural host model. Genital transmission of FIV was monitored in recipient cats by the appearance of viral antibodies to FIV Gag proteins and by virus isolation of blood leukocytes as measured by FIV reverse transcriptase activity and FIV-specific PCR. Microbicidal activity was considered effective when the treated cats did not show evidence of FIV infection for up to 18 weeks postchallenge. An aggregate analysis of 46 specific-pathogen-free cats revealed that a single dose of the infected cell inoculum efficiently transmitted FIV infection when delivered into the vagina (100%) or rectum (66%). Pretreatment of the vagina or rectum with 2% WHI-07 alone or in combination with 0.25% VDDTC significantly (P = 0.004) protected cats from genital transmission by the highly infectious inoculum (7 million FIV(Bangston)-infected feline T cells). Collectively, using the vaginal and rectal transmucosal model for FAIDS, our studies demonstrated that WHI-07 either alone or in combination with a vanadocene has clinical potential for the development of a dual-function anti-HIV microbicide for sexually active women.

Developmental toxicology studies of WHI-07, a novel nucleoside analogue-based dual-function microbicide, administered intravaginally to rabbits

The zidovudine derivative, 5-bromo-6-methoxy-5,6-dihydro-3-azidothymidine-5'-(p-bromophenyl) methoxy alaninyl phosphate (WHI-07), is a dual-function spermicidal and anti-HIV agent with contraceptive and microbicidal activity. In previous subchronic and reproductive toxicity studies and a two-year carcinogenicity study, daily intravaginal application of 0.5 to 2.0% WHI-07 via a gel-microemulsion, was shown to cause no local, systemic and reproductive toxicity or increased carcinogenicity in mice. To evaluate the developmental toxicity potential of WHI-07 in a nonrodent model, subgroups of 20 superovulated NZW rabbits were artificially inseminated and exposed intravaginally to a gel-microemulsion containing 0, 0.5, 1.0, or 2.0% WHI-07 during major organogenesis [gestation days 6-18]. The dose of WHI-07 was equivalent to 1.4x10(6) to 5.7x10(6) times its anti-HIV IC50 and 1400 to 5700 times its spermicidal EC50. Throughout the duration of the experiment (GD 0-29), clinical observations, food consumption, and body weights were recorded. Reproductive and fetal parameters were evaluated following uterotomies on GD 29. Measurements included numbers of corpora lutea, pregnancy, number and distribution of implantations, resorptions, live and dead fetuses, fetal weight, sex ratio, and gross external and skeletal malformations and variations. Maternal food consumption and body weight gain were unaffected by WHI-07 treatment. Hematologic and clinical chemistry determinations on GD 19 and 29 revealed no treatment-related maternal effects. Prior studies of repeated intravaginal administration of WHI-07 gel-microemulsion revealed lack of local toxicity to rabbit vaginal mucosa. In the current study, no drug-related gross lesions were apparent at necropsy. Reproductive indices, ie, pregnancy rate, gravid uterine weights, litter size, number of corpora lutea, implantation sites, pre- and postimplantation losses, viable fetuses, resorptions, fetal body weights, and fetal sex ratio, were not affected by intravaginal exposure to WHI-07. External, and skeletal examinations of fetuses for malformations and variations did not reveal any evidence of teratogenicity in any WHI-07-treated groups. Intravaginal administration of WHI-07 at concentrations as high as 2% did not produce teratogenicity or other developmental toxicity in rabbit conceptus. These findings indicated that WHI-07 shows unique clinical potential to become the active ingredient of a new female-controlled topical microbicidal vaginal contraceptive for women who are at high risk of acquiring HIV/AIDS.

Stampidine is a potential nonspermicidal broad-spectrum anti-human immunodeficiency virus microbicide

OBJECTIVE

Stampidine (2,'3'-didehydro-3'-deoxythymidine-5'-(p-bromophenyl methoxy alaninyl phosphate) is a novel aryl phosphate derivative of stavudine/d4T with broad-spectrum anti-HIV activity in vitro and in vivo. This study investigated the potential utility of stampidine as a nonspermicidal microbicide.

DESIGN

Prospective, controlled study.

SETTING

Center for Advanced Preclinical Sciences and Reproductive Biology Department.

PATIENT(S)

Seven sperm donors.

ANIMAL(S)

Fifty-two sexually mature, female and twenty-four male New Zealand white rabbits.

INTERVENTION(S)

Human semen and genital tract epithelial cells were exposed to stampidine (up to 1 mM). Ovulated does in subgroups of 12 were artificially inseminated with rabbit semen pretreated with stampidine (1 mM) or vehicle. Does in subgroups of four and three, respectively, were exposed intravaginally to a gel or a thermoreversible ovule formulation with and without 0.5%, 1.0%, or 2.0% stampidine (9 to 36 mM) for 14 days.

MAIN OUTCOME MEASURE(S)

Effect of stampidine on human sperm motility, kinematics, penetration through cervical mucus, and epithelial cell viability. Reproductive parameters on gestation day 8. Vaginal tissues were histologically scored 24 hours after dosing.

RESULT(S)

Exposure of human sperm to stampidine even at a concentration 10(6)-times higher than its in vitro anti-HIV-1 activity (50% inhibitory concentration = 1 nM) had no adverse effect on sperm motility, kinematics, cervical mucus penetrability, or the viability of vaginal and endocervical epithelial cells. Reproductive indices of pregnancy rate, embryo implantation, and preimplantation losses were not affected by pretreatment of rabbit semen with stampidine. Gel formulations of 0.5% to 2.0% stampidine (9 to 36 mM) lacked mucosal toxicity.

CONCLUSION(S)

The broad-spectrum anti-HIV agent stampidine had no adverse effect on sperm functions, was not cytotoxic, and did not induce mucosal toxicity. Stampidine has clinical potential as a prophylactic microbicide without contraceptive activity.

Clinical development of microbicides for the prevention of HIV infection

The HIV/AIDS pandemic continues its spread at a rate of over 15,000 new infections every day. Sexual transmission of HIV-1 is the dominant mode of this pandemic spread. For the first time since the disease emerged in the early 1980s, about half the 42 million people now living with HIV/AIDS worldwide are women. Worldwide, more than 90 percent of all adolescent and adult HIV infections have resulted from heterosexual intercourse. The "feminization" of the pandemic largely driven by the social, economic, and biological factors warrants urgent attention particularly for the adolescent female population. In the absence of an effective prophylactic anti-HIV therapy or vaccine, current efforts are aimed at developing intravaginal/intrarectal topical formulations of anti-HIV agents or microbicides to curb the mucosal and perinatal HIV transmission. Microbicides would provide protection by directly inactivating HIV or preventing HIV from attaching, entering or replicating in susceptible target cells as well as dissemination from target cells present in semen or the host cells that line the vaginal/rectal wall. Thus, ideally, anti-HIV microbicides should be capable of attacking HIV from different angles. In addition, a contraceptive microbicide could help prevent unintended pregnancies worldwide. To be a microbicide, these agents must be safe, effective following vaginal or rectal administration, and should cause minimal or no genital symptoms following long-term repeated usage. A safe and efficacious anti-HIV microbicide is not yet available despite the fact that more than 60 candidate agents have been identified to have in vitro activity against HIV, 18 of which have advanced to clinical testing. Targeting HIV entry has been a favored approach because it is the first step in the process of infection and several readily available anionic polymeric products seem to variably interfere with these processes are the primary candidates for potential microbicides. Formulations of some anionic polymeric antiviral agents have been tested at various doses and various durations for safety, tolerability, and acceptability in Phase I/II clinical trials (vaginal, rectal, or penile studies) in HIV-uninfected and/or HIV-infected populations. Current multicenter Phase I/II safety and Phase II/III efficacy studies that are being conducted or planned in different geographical locations by various special interest groups are designed for rapid clinical development of candidate products. The currently marketed detergent-type spermicide, nonoxynol-9 (N-9), has failed in Phase III clinical trials, due to the drug-induced formation of localized genital lesions that might in fact actually promote virus transmission. Alternative "first-generation" microbicides that have undergone Phase I/II safety and tolerability studies in HIV-uninfected and/or HIV-infected volunteers include polymeric viral fusion inhibitors (dextrin sulfate/Emmelle, carrageenans [PC-213, PC-503, PC-515/Carraguard], cellulose sulfate/Ushercell, polystyrene sulfonate, naphthalene sulfonate [PIC 024-4/PRO 2000/5], acidifying gel [Carbomer 974P/BufferGel], Lactobacillus (L. crispatus) suppository/CTV-05, detergent-type dual-function barriers [ACIDFORM, GEDA Plus, SURETE, Glyminox/C31G/Savvy, Invisible Condom], herbal extracts [Praneem], and viral replication inhibitors [PMPA/Tenofovir]. For majority of these products, no information is available regarding their long-term mucosal safety, carcinogenicity potential, bioavailability, or efficacy following their extended vaginal or rectal exposure. The irritative genitourinary symptoms reported for a number of these first-generation products in Phase I clinical trials implies that the "soft" preclinical endpoints for mucosal safety established for the use and development of vaginal spermicides may not be rigorous enough for vaginal and rectal microbicides because of the efficient sexual tra virus diversity, and genetic environment. It is now apparent that sexually transmitted R5 HIV-1 viruses have less positive charge on their surface compared with the R4 HIV-1 viruses, which may limit the anionic polymers as topical microbicides despite extensive clinical trials. Nevertheless, their ongoing clinical trials, reviewed here, using optimized formulations, and special populations in various geographic locations are paving the way for future rigorous clinical testing of "mechanism-based" broad-spectrum anti-HIV microbicides that are currently under intense development. It is anticipated that future microbicide trials will focus on combination of products capable of attacking HIV life cycle at multiple steps intended to increase efficacy, limit cross-resistance as well as minimize microbicide-induced host toxicity.

A 13-week subchronic intravaginal toxicity study of pokeweed antiviral protein in mice

Pokeweed antiviral protein (PAP), a 29-kDa plant-derived protein isolated from Phytolacca americana, is a broad-spectrum antiviral agent. PAP shows unique clinical potential to become the active ingredient of a non-spermicidal microbicide because of its potent in vivo anti-HIV activity, non-interference with in vivo sperm functions, and lack of cytotoxicity to genital tract epithelial cells. Over 13 weeks the subchronic and reproductive toxicity potential of an intravaginally administered gel formulation of PAP was studied in mice to support its further development as a vaginal microbicide. Female B6C3F1 and CD-1 mice in subgroups of 20, were exposed intravaginally to a gel formulation containing 0, 0.025, 0.05, or 0.1% PAP, 5 days/week for 13 consecutive weeks. On a molar basis, these concentrations are 500- to 2000-times higher than the in vitro anti-HIV IC50 value. After 13 weeks of intravaginal treatment, B6C3F1 mice were evaluated for survival, body weight gain, and absolute and relative organ weights. Blood was analyzed for hematology and clinical chemistry profiles. Microscopic examination was performed on hematoxylin and eosin-stained tissue sections from each study animal. Placebo-control and PAP-dosed female CD-1 mice were mated with untreated males in order to evaluate if PAP has any deleterious effects on reproductive performance. There were no treatment-related mortalities. Mean body weight gain was not reduced by PAP treatment during the dosing period. The hemogram and blood chemistry profiles revealed lack of systemic toxicity following daily intravaginal instillation of PAP for 13 weeks. No clinically significant changes in absolute and relative organ weights were noted in the PAP dose groups. Extensive histopathological examination of tissues showed no increase in treatment-related microscopic lesions in any of the three PAP dose groups. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of PAP for 13 weeks showed no adverse effect on their subsequent reproductive capability (100% fertile), neonatal survival (>90%) or pup development. Collectively, these findings demonstrate that repetitive intravaginal administration of PAP at concentrations as high as 2000 times its in vitro anti-HIV IC50 value was not associated with local or systemic toxicity and did not adversely affect the reproductive performance of mice. PAP may be useful as an active ingredient of a safe vaginal microbicide for prevention of the sexual transmission of viruses, particularly of HIV-1.

Development and evaluation of a thermoreversible ovule formulation of stampidine, a novel nonspermicidal broad-spectrum anti-human immunodeficiency virus microbicide

Stampidine [2',3'-didehydro-2',3'-dideoxythymidine 5'-[p-bromophenyl methoxyalaninyl phosphate], a prodrug of stavudine (STV/d4T) with improved anti-HIV activity, is undergoing development as a novel nonspermicidal microbicide. Here, we report the stability of stampidine as a function of pH, preparation of a novel thermoreversible ovule formulation for mucosal delivery, its dissolution profile in synthetic vaginal fluid, and its mucosal toxicity potential as well as systemic absorption in the rabbit model. Stampidine was most stable under acidic conditions. Stampidine was solubilized in a thermoreversible ovule formulation composed of polyethylene glycol 400, polyethylene glycol fatty acid esters, and polysorbate 80. Does were exposed intravaginally for 14 days to an ovule formulation with and without 0.5%, 1%, or 2% stampidine corresponding to 1 x 107- to 4 x 107-fold higher than its in vitro anti-HIV IC50 value. Vaginal tissues harvested on Day 15 were evaluated for mucosal toxicity and cellular inflammation. Additionally, does were exposed intravaginally to stampidine, and plasma collected at various time points was assayed by analytical HPLC for the prodrug and its bioactive metabolites. Stampidine did not cause mucosal inflammation. The vaginal irritation scores for 0.5-2% stampidine were within the acceptable range for clinical trials. The prodrug and its major metabolites were undetectable in the blood plasma. The marked stability of stampidine at acidic pH, its rapid spreadability, together with its lack of mucosal toxicity or systemic absorption of stampidine via a thermoreversible ovule may provide the foundation for its clinical development as an easy-to-use, safe, and effective broad-spectrum anti-HIV microbicide without contraceptive activity.

Contraceptive activity of a spermicidal aryl phosphate derivative of bromo-methoxy zidovudine (compound WHI-05) in rabbits

WHI-05 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate, CAS 213982-93-5) is a highly promising anti-viral and spermicidal agent with clinical potential as a vaginal contraceptive which can prevent the sexual transmission of AIDS. In this study, the contraceptive activity of WHI-05 in rabbits was evaluated. Exposure of semen to WHI-05 at the time of artificial insemination inhibited pregnancy and embryo implantation by 90%. Intravaginal application of 2% WHI-05 containing gel also inhibited the pregnancy rate by 90%. WHI-05 had no side effects for the offspring of rabbits who became pregnant despite WHI-05.

Phenylarsonic acid compounds with broad-spectrum and potent cytotoxic activity against human cancer cells

The in vitro cytotoxic activity profile of nine novel phenylarsonic acid (CAS 98-05-5, PAA) compounds against 17 human cancer cell lines including (a) ovarian cancer cell lines ES-2, PA-1, CAOV-3, OVCAR-3, (b) testicular cancer cell lines Ntera-2, Tera-2, N2NICP, 833K, and 64CP, (c) multiple myeloma cell lines ARH77, HS-Sultan, RPMI-8226, and U266, and (d) acute lymphoblastic leukemia (ALL) cell lines NALM-6, MOLT-3, ALL-1, and RS4; 11, was determined by the MTT assay. The lead compounds, 2-methylthio-4-[(4'-aminophenylazo)-phenylarsonic acid] pyrimidine (PHI-370) and 2-methylthio-4-(4'-phenylarsonic acid)-aminopyrimidine (PHI-380) caused apoptotic death in all 17 cancer cell lines at low micromolar concentrations, as documented by TUNEL assays and confocal laser scanning microscopy. PHI-380 was also tested and found to be very active against primary tumor cells isolated from surgical biopsy specimens of 14 patients with therapy-refractory non-small cell lung cancer, breast cancer, colon cancer, lymphoma, hepatoblastoma, or Wilm's tumor as well. Because of their broad-spectrum and potent anticancer activity and ability to induce apoptosis in primary tumor cells from therapy-refractory cancer patients, PAA compounds such as PHI-370 and PHI-380 may provide the basis for effective salvage regimens for patients with recurrent cancer.

Contraceptive activity of a spermicidal aryl phosphate derivative of bromo-methoxy-zidovudine (compound WHI-07) in rabbits

OBJECTIVE

To determine the vaginal contraceptive activity of WHI-07 in the rabbit model.

DESIGN

Prospective, controlled study.

SETTING

Center for advanced preclinical sciences.

ANIMAL(S)

Subgroups of 15, 16, or 24 New Zealand White does and 24 bucks per experiment.

INTERVENTION(S)

Ex vivo (Experiment 1) and in vivo (Experiments 2 and 3) treatment of semen with WHI-07 or Nonoxynol-9 (N-9). In Experiment I, ovulated does in subgroups of 15 were artificially inseminated with semen mixed with WHI-07 or vehicle. In Experiment 2, ovulated does in subgroups of 24 were artificially inseminated within 2 min after intravaginal administration of 2% WHI-07 gel-microemulsion or 2% N-9 gel and allowed to complete term pregnancy. In Experiment 3, ovulated does in subgroups of 16 were artificially inseminated at 15, 30, or 60 minutes.

MAIN OUTCOME MEASURE(S)

The numbers of implanted embryos on postinsemination day 8 or the proportion of does that became pregnant and delivered newborn rabbits; the litter size, weight, growth, and viability of pups until lactation day 5.

RESULT(S)

Exposure of semen to WHI-07 at the time of artificial insemination completely inhibited pregnancy rates (WHI-07-pretreated, 0%, vs. control, 60%) and embryo implantation (WHI-07-pretreated, 0/175 vs. control, 68/170). Intravaginal administration of a 2% WHI-07 gel-microemulsion or 2% N-9 gel before artificial insemination significantly inhibited pregnancy rates (81% and 85% inhibition, respectively) when compared with control. Furthermore, the 2% WHI-07 gel-microemulsion provided >90% inhibition of fertility even when insemination was delayed until 60 minutes after intravaginal application. Rabbits that delivered litters despite intravaginal application of 2% WHI-07 gel-microemulsion had healthy offsprings with no perinatal or postnatal repercussions.

CONCLUSION(S)

WHI-07 is a potent contraceptive agent in vivo. Intravaginal use of WHI-07 gel-microemulsion has clinical potential as a safe prophylactic contraceptive, in addition to its microbicide activity to curb the sexual transmission of HIV.

Potent dual anti-HIV and spermicidal activities of novel oxovanadium(V) complexes with thiourea non-nucleoside inhibitors of HIV-1 reverse transcriptase

We have previously demonstrated that tetrahedral bis(cyclopentadienyl)vanadium(IV) complexes and square pyramidal oxovanadium(IV) complexes of vanadium are rapid and selective spermicidal agents at low micromolar concentrations. This study investigated the potential utility of oxovanadium in combination with thiourea non-nucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) for the development of an effective dual-function anti-HIV spermicide. Two rationally designed substituted phenyl-ring containing pyridyl thiourea NNIs, N-[2-(2-chlorophenethyl)]-N(')-[2-(5-bromopyridyl)-thiourea) [1] and N-[2-(2-methoxyphenethyl)]-N(')-[2-(pyridyl)-thiourea [2] that exhibited subnanomolar IC(50) values against the drug-sensitive, drug-resistant, and multidrug-resistant strains of HIV-1, were complexed with oxovanadium. The oxovanadium-thiourea [OVT] NNIs, C(29)H(27)Br(2)Cl(2)N(6)O(2)S(2)V [3], and C(31)H(35)N(6)O(4)S(2)V [4], were synthesized by reacting VOSO(4), a V(IV) compound, with the corresponding deprotonated thiourea NNI compounds as ligands. Elemental analysis showed that each OVT-NNI used two thiourea molecules as ligands. The existence of the Vz.dbnd6;O bond (968cm(-1)) was confirmed by IR spectroscopy. No d-d bands were observed in the visible spectra of OVT-NNIs and their EPR spectra were featureless, indicating that the vanadium centers were oxidized to V(V). The new OVT-NNIs as well as their thiourea NNI ligands were evaluated for (i) anti-HIV activity using the cell-free recombinant RT inhibition assays, (ii) cellular HIV replication assays, (iii) spermicidal activity against human sperm by computer-assisted sperm analysis (CASA), and (iv) cytotoxicity against normal human female genital tract epithelial cell using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) dye-reduction assays. Similar to thiourea NNIs 1 and 2, the OVT-NNIs 3 and 4, exhibited potent anti-HIV activity with submicromolar IC(50[p24]) values (0.08 and 0.128 microM, respectively) and submicromolar IC(50[RT]) values (2.1 and 0.87 microM, respectively). Notably, OVT-NNIs were spermicidal against human sperm at low micromolar concentrations (IC(50)=34 and 55 microM, respectively) and induced rapid sperm immobilization (T(1/2)=12 and 240s) when compared with their respective thiourea NNI ligands (EC(50)=>400 microM and T(1/2)=>180min). Moreover, OVT-NNIs displayed high selectivity indices against normal female genital tract epithelial cells (IC(50) values >250 microM) when compared to the detergent-type spermicide, nonoxynol-9, which was cytotoxic at spermicidal concentrations (IC(50) values 32-64 microM). This is the first report on the dual anti-HIV and spermicidal activities of a vanadium/oxovanadium complex. Our discovery of potent anti-HIV and rapid spermicidal activities of OVT-NNIs may be useful for the development of an effective and safe vaginal anti-HIV spermicide for women who are at high risk for acquiring HIV/AIDS by heterosexual transmission.

Structural requirements for potent anti-human immunodeficiency virus (HIV) and sperm-immobilizing activities of cyclohexenyl thiourea and urea non-nucleoside inhibitors of HIV-1 reverse transcriptase

The current pandemic of sexually transmitted human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) has created an urgent need for a new type of microbicide, one that is both a spermicide and a virucide. In a systematic effort to identify a non-detergent-type antiviral spermicide, we have rationally designed and synthesized a series of cyclohexenyl thiourea (CHET) nonnucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) with sperm-immobilizing activity (SIA). To gain further insight into the structural requirements for the optimal activity of these dual-function NNIs, we compared the effects of thiazolyl, benzothiazolyl, and pyridyl ring substitutions and functionalization with electron-donating and electron-withdrawing groups as well as the importance of thiourea and urea moieties of 15 heterocyclic ring-substituted NNIs. RT activity and p24 antigen production in HIV-infected peripheral blood mononuclear cells were used as markers of viral replication. Computer-assisted sperm analysis was used for evaluating SIA of CHET compounds. The rabbit model was used for evaluation of in vivo mucosal toxicity and contraceptive activity of the lead NNIs. Three CHET-NNIs with a bromo, chloro, or methyl substitution at the 5 position of the pyridyl ring exhibited potent anti-HIV activity at nanomolar concentrations (IC(50) = 3-5 nM) and SIA at micromolar concentrations (EC(50) = 45-96 micro M). The dual-function CHET-NNIs were potent inhibitors of drug-resistant HIV-1 strains with genotypic and phenotypic NNI resistance. Upon substitution of the sulfur atom of the thiourea moiety with an oxygen atom, the most striking difference noted was a 38-fold reduction in time required for 50% sperm immobilization (T(1/2)). A quantitative structure-activity relationship (QSAR) analysis was used in deriving regression equations between 20 physicochemical properties and SIA of NNIs. QSAR analysis showed that the T(1/2) values positively correlated with values for molecular refractivity (r = 0.88), hydrophobicity (r = 0.72), atomic polarizability (r = 0.70), and principal moment of inertia (r = 0.63) of spermicidal NNIs. A stepwise multiple regression model to describe the relationship of T(1/2) values with these four regressors provided excellent predictability (r = 0.93). Exposure of semen to thiourea/urea NNIs either alone or in combination at the time of artificial insemination led to marked or complete inhibition of pregnancy in rabbits as assessed by the number of embryo implants versus corpora lutea on Day 8 of pregnancy. Repeated intravaginal application of a gel-microemulsion with and without 0.5%, 1%, and 2% CHET-NNI or its urea analog either alone or in combination did not induce mucosal toxicity. We hypothesize that the gain of spermicidal function by CHET-NNIs is due to their metabolic oxidation to urea analogs by sperm. Three reaction pathways are discussed. The extremely rapid SIA of the urea analog as well as the broad-spectrum anti-HIV activity of spermicidal CHET-NNIs together with their lack of mucosal toxicity and the marked ability to reduce in vivo fertility is particularly useful for the clinical development of a dual-function spermicidal microbicide. The cyclohexenyl pyridyl NNIs, especially N-[2-(1-cyclohexenyl)ethyl] N'-[2-(5-bromopyridyl)]-thiourea in combination with the urea analog, show unique clinical potential as anti-HIV spermicides aimed at curbing the sexual transmission of multidrug-resistant HIV-1 while providing effective fertility control for women.

Pre-clinical safety evaluation of novel nucleoside analogue-based dual-function microbicides (WHI-05 and WHI-07)

Compounds WHI-05 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl)-methoxyalaninyl phosphate] and WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate] are aryl phosphate derivatives of zidovudine (ZDV) with anti-HIV and contraceptive activity. WHI-05 and WHI-07 differ fundamentally from currently used surfactant microbicides that are cytotoxic to genital tract epithelial cells at spermicidal concentrations. These drugs were rationally designed to bypass the thymidine kinase dependency of ZDV activation in genital tract secretions, as well as to achieve spermicidal activity. WHI-05 and WHI-07 were formulated via a non-toxic gel-microemulsion for intravaginal use as potential anti-HIV spermicides. Pre-clinical safety studies of intravaginally administered WHI-05 and WHI-07 gel-microemulsions were performed in mice and rabbits to mimic closely the intravaginal application of a microbicidal preparation in women. In addition, systemic toxicity studies were performed in mice and non-human primates. The LD10 doses for WHI-05 and WHI-07 when administered intravenously or intraperitoneally were >500 mg/kg for mice. Female cynomolgus monkeys treated with 20 mg/kg WHI-05 and WHI-07 intravenously developed no grade 2-4 systemic toxicities. Repetitive intravaginal administration of 2% WHI-05 and WHI-07 via a gel-microemulsion to achieve concentrations as high as 6.1 x 10(4) and 5.7 x 10(6) times their respective in vitro anti-HIV IC50 values, and 1200 and 5700 times their spermicidal EC50 values, for up to 13 weeks, was not associated with mucosal, systemic or reproductive toxicity. Furthermore, long-term (2 years) intravaginal administration of 2% WHI-07 gel-microemulsion was not associated with systemic toxicity or increased carcinogenicity in mice. The improved potency, as well as the lack of mucosal, systemic and reproductive toxicity of WHI-05 and WHI-07, means that these compounds have clinical potential as safe, prophylactic contraceptives in addition to their microbicide activity to curb the sexual transmission of HIV.

Metvan: a novel oxovanadium(IV) complex with broad spectrum anticancer activity

Among the 25 bis(cyclopentadienyl)vanadium(IV) and 14 oxovanadium(IV) compounds synthesised and evaluated for anticancer activity, bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) (metvan) was identified as the most promising multitargeted anticancer vanadium complex with apoptosis-inducing activity. At nanomolar and low micromolar concentrations, metvan induces apoptosis in human leukaemia cells, multiple myeloma cells and solid tumour cells derived from breast cancer, glioblastoma, ovarian, prostate and testicular cancer patients. It is highly effective against cisplatin-resistant ovarian cancer and testicular cancer cell lines. Metvan is much more effective than the standard chemotherapeutic agents dexamethasone and vincristine in inducing apoptosis in primary leukaemia cells from patients with acute lymphoblastic leukaemia, acute myeloid leukaemia or chronic acute myeloid leukaemia. Metvan-induced apoptosis is associated with a loss of mitochondrial transmembrane potential, the generation of reactive oxygen species and depletion of glutathione. Treatment of leukaemia cells from acute lymphoblastic leukaemia, acute myeloid leukaemia and chronic acute myeloid leukaemia patients with metvan inhibits the constitutive expression as well as the gelatinolytic activities of matrix metalloproteinase-9 and -2. Treatment of human malignant glioblastoma and breast cancer cells with metvan at concentrations > 1 microM is associated with a nearly complete loss of the adhesive, migratory and invasive properties of the treated cancer cell populations. Metvan shows favourable pharmacokinetics in mice and does not cause acute or subacute toxicity at the dose levels tested (12.5 - 50 mg/kg). Therapeutic plasma concentrations > or = 5 microM, which are highly cytotoxic against human cancer cells, can be rapidly achieved and maintained in mice for at least 24 h after intraperitoneal bolus injection of a single 10 mg/kg non-toxic dose of metvan. Metvan exhibits significant antitumour activity, delays tumour progression and prolongs survival time in severe combined immunodeficient mouse xenograft models of human malignant glioblastoma and breast cancer. The broad spectrum anticancer activity of metvan together with favourable pharmacodynamic features and lack of toxicity warrants further development of this oxovanadium compound as a new anticancer agent. Metvan could represent the first vanadium complex as an alternative to platinum-based chemotherapy.

A 13-week subchronic intravaginal toxicity study of the novel broad-spectrum anti-HIV and spermicidal agent, N-[2-(1-cyclohexenyl)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (PHI-346) in mice

The nonnucleoside inhibitor (NNI) of HIV-1 reverse transcriptase, PHI-346 (N-[2-(1-cyclohexenyl)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea), is a dual-function spermicidal agent with potent anti-HIV activity against drug-sensitive as well as drug-resistant HIV-1 strains with genotypic and phenotypic NNI resistance. PHI-346 was formulated via a lipophilic gel-microemulsion for intravaginal use as a potential dual-function microbicide. To evaluate the toxicity potential of short-term intravaginal exposure to PHI-346, groups of 15 female B6C3F1 and CD-1 mice were exposed intravaginally to a gel-microemulsion containing 0, 0.5, 1.0, or 2.0% PHI-346, 5 days per week for 13 consecutive weeks. On a molar basis, these concentrations of PHI-346 are 350 to 1,400-times higher than its spermicidal EC50 and nearly 5 x 10(6) to 2 x 10(7) times higher than its in vitro anti-HIV IC50. After 13 weeks of intravaginal treatment, B6C3F1 mice were evaluated for survival, body weight gain, absolute and relative organ weights. Blood was analyzed for hematology and clinical chemistry profiles. Microscopic examination was performed on hematoxylin and eosin-stained tissue sections from each study animal. Placebo control and PHI-346 dosed female CD-1 mice were mated with untreated males in order to evaluate if PHI-346 has any deleterious effects on the reproductive performance. There were no treatment-related mortalities. Mean body weight gain during the dosing period was not reduced by PHI-346 treatment. The hemogram or blood chemistry profiles revealed lack of systemic toxicity following daily intravaginal instillation of PHI-346 for 13 weeks. No clinically significant changes in absolute and relative organ weights were noted in PHI-346 dose groups. Extensive histopathological examination of tissues revealed no treatment-related abnormalities in any of the three PHI-346 dose groups. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of PHI-346 for 13 weeks had no adverse effect on their subsequent reproductive capability, perinatal outcome, growth, and development of offspring. Collectively, these findings demonstrate that repetitive intravaginal administration of PHI-346 at concentrations as high as 1,400-times its spermicidal EC50 and 2 x 10(7) times its in vitro anti-HIV IC50 was not associated with local or systemic toxicity and did not adversely affect the reproductive performance in mice. PHI-346 may be useful as an active ingredient of a safe vaginal microbicide for prevention of the sexual transmission of multidrug-resistant HIV-1.

Two-year toxicity and carcinogenicity studies in B(6)C(3)F(1) mice with 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), a novel anti-HIV and contraceptive agent

The zidovudine derivative, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxy alaninyl phosphate (WHI-07), is a dual-function spermicidal and anti-HIV agent with contraceptive and microbicidal activity. In previous two subchronic toxicity studies, intravaginal application of 0.5-2.0% WHI-07, for up to 13 weeks, was shown to cause no local, systemic or reproductive toxicity. To evaluate the toxicity and carcinogenic potential of long-term exposure to WHl-07, groups of 50 female B(6)C(3)F(1) mice were given no treatment or exposed intravaginally to a gel-microemulsion formulation with and without 2.0% WHI-07, 5 days per week for 2 years. The dose of WHI-07 was equivalent to 5700 times its spermicidal EC(50) and 5.7x10(6) times its anti-HIV IC(50). The endpoints that were evaluated included survival, body weight, hematologic and clinical chemistry profiles, absolute and relative organ weights, and histopathology. No significant differences in mean body weight gain and survival were found among the groups of untreated control, placebo control, and 2% WHI-07-treated mice at the end of the 2-year study. The hematological and clinical chemistry profiles did not reveal any toxicologically significant changes that could be attributed to WHI-07 treatment. No clinically significant changes in absolute and relative organ weights were noted in the WHI-07 group. A variety of neoplastic and nonneoplastic lesions which were considered incidental, related to aging, or procedural, were observed in both the untreated and intravaginally treated groups. The proportion of animals with malignant tumors, the total number of malignant tumors, as well as the types of malignant tumors in the three groups was similar. The cumulative incidence of microscopic lesions in various organs showed that malignant lymphoma was the major cause of death in aging female B(6)C(3)F(1) mice, the incidence of which was unaffected by intravaginal treatment. We conclude that long-term intravaginal administration of WHI-07 is not associated with systemic toxicity or increased carcinogenicity in mice. WHI-07 has clinical potential as an active ingredient of a safe vaginal/rectal microbicide.

Subchronic (13-week) toxicity studies of intravaginal administration of spermicidal vanadocene acetylacetonato monotriflate in mice

Bis-cyclopentadienyl complexes of vanadium(IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. In this study, groups of 10 B(6)C(3)F(1) and 20 CD-1 female mice were exposed intravaginally to a gel-microemulsion containing 0, 0.06, 0.12, or 0.25% of a representative vanadocene, vanadocene acetylacetonato monotriflate (VDACAC), five days per week for 13 consecutive weeks. The doses of VDACAC used were nearly 300- to 1250-fold higher than its in vitro spermicidal EC(50) value. After 13 weeks of intravaginal treatment, B(6)C(3)F(1) mice were evaluated for survival, body weight gain, absolute and relative organ weights, and systemic toxicity. Blood was analyzed for hematological and clinical chemistry profiles. Microscopic examination was performed on hematoxylin- and eosin-stained tissue sections from each study animal. Vanadium content in tissues was determined by atomic absorption spectroscopy. Gel-microemulsion (placebo) control and VDACAC dosed female CD-1 mice were mated with untreated males in order to evaluate if VDACAC has any adverse effects on the reproductive outcome. There were no treatment-related mortalities in either study. Mean body weight gain during the dosing period was not reduced by VDACAC treatment. Hemograms or clinical chemistry profiles did not reveal any toxicologically significant changes attributed to VDACAC treatment. No clinically significant dose-dependent changes in absolute and relative organ weights were noted in VDACAC dose groups. Extensive histopathological examination of tissues revealed no treatment-related abnormalities in any of the three VDACAC dose groups. Vanadium was not incorporated in mouse tissues at levels above 1 microg/g. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of VDACAC for 13 weeks had no adverse effect on their subsequent reproductive capability (100% fertile), neonatal survival (>96%) or pup development. Collectively, these findings demonstrate that repetitive intravaginal administration of VDACAC to yield effective spermicidal concentrations (<0.1%) in the vagina was not associated with systemic toxicity and did not adversely affect the reproductive performance in mice. The spermicidal vanadocene-chelated complex, VDACAC, may be useful as a safe vaginal contraceptive.

Human sperm immobilizing activity of aminophenyl arsenic acid and its N-substituted quinazoline, pyrimidine, and purine derivatives: protective effect of glutathione

We examined the potential toxicity of pentavalent organic arsenicals for human sperm. We used computer-assisted sperm analysis to examine the effects of three aminophenyl arsenicals and their nine N-substituted quinazoline, pyrimidine, and purine derivatives on human sperm motility and kinematics in human semen and medium. Among the arsenicals examined, (aminophenylazo)-phenyl arsonic acid and its N-substituted pyrimidine derivative PHI-370 (2-methylthio-4-[(4'-aminophenylazo)-phenylarsonic acid] pyrimidine) exhibited rapid sperm immobilizing activity in medium with EC(50) values of 77 and 82 microM, respectively, and t(1/2) of < 3 min. Molecular modeling analysis indicated that sperm-immobilizing organic arsenicals exhibit high dipole moments (>7 Debyes). Sperm immobilizing activity of these arsenicals was completely abrogated in the presence of seminal plasma. Furthermore, coincubation of motile sperm with PHI-370 in the presence of reduced glutathione (GSH) resulted in dose-dependent protection of sperm motility and sperm motion parameters. Coincubation of the arsenical with GSH at a molar ratio of 1:20 resulted in 95% retention of sperm progressive motility. The mean values of the other sperm movement characteristics also showed > 90% protection. These observations suggest that the rapid sperm immobilizing activity of these pentavalent arsenicals may be as a result of direct binding of the arsenical with the sperm thiol components essential for sperm motility as well as induction of oxidative damage by disruption of sperm cell's antioxidant system. Sodium arsanilate and its N-substituted pyrimidine derivative, PHI-370, are useful probes to further evaluate the mechanism of pentavalent arsanilate-induced human sperm dysfunction.

Effect of pretreatment of semen with pokeweed antiviral protein on pregnancy outcome in the rabbit model

OBJECTIVE

To determine whether artificial insemination of semen pretreated with pokeweed antiviral protein, a 29-kD antihuman immunodeficiency virus (HIV) protein purified from the leaves of Phytolacca americana, has any adverse effects on pregnancy outcome in the rabbit model.

DESIGN

Prospective, controlled study.

SETTING

Center for Advanced Preclinical Sciences at the Parker Hughes Institute.

ANIMAL(S)

Forty-eight female and 12 male New Zealand White rabbits.

INTERVENTION(S)

Fresh pooled semen obtained from 12 bucks was treated for 1 hour with and without 100 microg/mL or 1000 microg/mL pokeweed antiviral protein. Ovulated does in groups of 16 were artificially inseminated with control and pokeweed antiviral protein-treated semen and allowed to complete term pregnancy.

MAIN OUTCOME MEASURE(S)

Proportion of does that became pregnant and delivered newborn rabbits; the litter size, weight, growth, and viability of pups until lactation day 5.

RESULT(S)

Pokeweed antiviral protein treatment of semen had no adverse effect on gestation length, pregnancy rate, perinatal outcome, growth, and development of the offspring.

CONCLUSION(S)

Pokeweed antiviral protein shows clinical potential as a safe, prophylactic antiviral agent in assisted reproduction in HIV-1 discordant couples.

Subchronic (13-week) toxicity studies of intravaginal administration of spermicidal vanadocene dithiocarbamate in mice

Spermicidal organometallic complexes of vanadium(IV) with bis(cyclopentadienyl) rings or vanadocenes are a new class of experimental contraceptive agents. In a systematic search for vanadocenes with selective spermicidal activity, we identified vanadocene dithiocarbamate (VDDTC) as the most potent and stable spermicidal compound. In this study, groups of 10 B(6)C(3)F(1) and 20 female CD-1 mice were exposed intravaginally to a gel-microemulsion containing 0, 0.06, 0.12, and 0.25% VDDTC 5 days per week for 13 consecutive weeks. The doses of VDDTC used were nearly 1250- to 5000-fold higher than its in vitro spermicidal EC(50) value. After 13 weeks of intravaginal treatment, B(6)C(3)F(1) mice were evaluated for survival, body weight gain, absolute and relative organ weights, and systemic toxicity. Blood was analyzed for hematologic and clinical chemistry parameters. Microscopic examination was performed on hematoxylin and eosin-stained tissue sections from each study animal. Vanadium content in tissues was determined by atomic absorption spectroscopy. Placebo control and VDDTC-dosed female CD-1 mice were mated with untreated males to evaluate whether VDDTC has any deleterious effects on the reproductive performance. There were no treatment-related effects on survival and mean body weight and mean body weight gain during the dosing period. The blood chemistry or hemogram profiles did not reveal any toxicologically significant changes that could be attributed to VDDTC treatment. No clinically significant changes in absolute and relative organ weights were noted in VDDTC dose groups. Extensive histopathological examination of tissues revealed no treatment-related abnormalities in any of the three VDDTC dose groups. The vanadium content of all mouse tissue analyzed was <1 microg/g. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of VDDTC for 13 weeks had no adverse effect on their subsequent reproductive capability (100% fertile), neonatal survival (>90%), or pup development. Collectively, these findings demonstrate that repetitive intravaginal administration of VDDTC to yield effective spermicidal concentrations (<0.1%) in the vagina was not associated with systemic toxicity and did not adversely affect the reproductive performance in mice. VDDTC may have clinical utility as an active ingredient of non-detergent type, safe, vaginal spermicidal contraceptives.

Gel-microemulsions as vaginal spermicides and intravaginal drug delivery vehicles

There is a need for novel formulations to improve the bioavailability through the vaginal/rectal mucosa of microbicidal drug substances against sexually transmitted diseases. In addition, there is a need for more effective and less toxic vaginal spermicides. Here we review our recent discovery of novel gel-microemulsions (GM) as nontoxic, dual-function intravaginal spermicides, which can be used as delivery vehicles for lipophilic drug substances targeting sexually transmitted pathogens. We describe the formulation and biologic properties of 2 novel, submicron-particle-size GMs, GM-4 and GM-144, which were prepared from commonly available pharmaceutical excipients. These GMs comprising oil-in-water microemulsion and polymeric hydrogels were designed to solubilize lipophilic antiviral/antimicrobial agents and exhibited rapid spermicidal activity in human semen. Preclinical studies comparing the in vivo contraceptive efficacy of GM-4 and GM-144 versus nonoxynol-9-based detergent spermicide (Gynol II) in the rigorous rabbit model confirmed the potent contraceptive activity of these GMs. Unlike nonoxynol-9, repeated intravaginal applications of GM-4 and GM-144 in the rabbit vaginal irritation test were not associated with local inflammation or damage of the vaginal mucosa or epithelium. Furthermore, in short-term toxicity studies performed in mice, repetitive intravaginal application of spermicidal GM-4 and GM-144 for up to 13 weeks was not associated with any local, systemic, or reproductive toxicity. Spermicidal GMs have unprecedented potential as dual function microbicidal contraceptives to improve vaginal bioavailability of poorly soluble antimicrobial agents without causing significant vaginal damage.

Members of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway are present and active in human sperm

OBJECTIVE

To investigate whether components of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway are present and active in human sperm.

DESIGN

Comparative study.

SETTING

Reproductive biology department.

PATIENT(S)

Nine sperm donors.

INTERVENTION(S)

Sperm were exposed to interferon-alpha (IFN-alpha), IFN-gamma, interleukin-12 (IL-12), Ca2+ ionophore (A23187), or progesterone under capacitating conditions.

MAIN OUTCOME MEASURE(S)

Cell lysates prepared from sperm and Jurkat T-cell line were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the expression of JAKs (1-3 and TYK 2) and STATs (1-6) was examined by Western blot analysis. Effect of IFN-alpha, IFN-gamma, IL-12, A23187, or progesterone on sperm STAT 1 or STAT 4 phosphorylation was determined by phospho-STAT 1 antibody or antiphosphotyrosine (APT) Western blot analysis. Indirect immunofluorescence and confocal laser scanning microscopy was used to confirm the specific staining of anti-TYK 2, anti-STAT 1, and anti-STAT 4 antibodies.

RESULT(S)

By Western blot analysis, only antibodies to TYK 2 of the JAK family, and antibodies to STAT 1 and STAT 4 members of the STAT family specifically recognized protein bands corresponding to TYK 2, STAT 1, and STAT 4 described in other cell types. By confocal microscopy, antibodies to TYK 2 reacted with the sperm tail as well as the apical region of sperm head, whereas antibodies to STAT 1 and STAT 4 reacted with the apical region of the sperm head. Tyrosine phosphorylation of STAT 1 in capacitated sperm was enhanced by IFN-alpha and IFN-gamma, and that of STAT 4 was enhanced by IL-12. Both A23187 and progesterone markedly inhibited tyrosine phosphorylation of sperm STAT 4.

CONCLUSION(S)

Members of the JAK/STAT proteins, TYK 2, STAT 1, and STAT 4 are present and active in human sperm. The localization of STAT 1 and STAT 4 proteins to the apical region of the sperm head and their activation by IFN-alpha, IFN-gamma, or IL-12 implicate a role for sperm STAT proteins in fertilization. We hypothesize that sperm-derived phosphorylated STAT 1 and STAT 4 could contribute to the pool of transcription factors during sperm-oocyte fusion as well as transmit signal to the oocyte nucleus. Therefore, defects in sperm TYK 2 and STAT 1- or STAT 4-mediated signaling pathway may have relevance to male factor infertility.

Bis(4,7-dimethyl and 5-dinitro-1,10-phenanthroline) sulfato-oxovanadium(IV)-mediated in vivo male germ cell apoptosis

Oxovanadium(IV) [VO] complexes of 1,10-phenanthroline are a new class of potent apoptosis-inducing cytotoxic agents against human testicular cancer cells in vitro. The present study investigated the in vivo ability of four(bis)-chelated 1,10-phenanthroline [phen] complexes of sulfato-oxovanadium(IV)-VO(phen)(2), VO(Cl-phen)(2), VO(Me(2)-phen)(2) and VO(NO(2)-phen)(2)-with and without substitutions, to induce testicular germ cell apoptosis. Male germ cell loss in mice was measured by determining the epididymal sperm count, testicular weight and histological evaluation of the testes. Repetitive intratesticular injection (7.5 mg kg(-1) testis(-1)) of bis-chelated 1,10-phenanthroline complexes of oxovanadium(IV) with 4,7-dimethyl [VO(Me(2)-phen)(2)] and 5-dinitro [VO(NO(2)-phen)(2)] substitution led to decreased sperm counts and reduced testicular weights. Histopathological examination of testicular sections from VO(Me(2)-phen)(2)- and VO(NO(2)-phen)(2)-treated mice revealed a marked inhibition of spermatogenesis and preferential loss of maturing, as well as elongated spermatids. In situ evaluation of seminiferous tubule cross-sections by terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick end-labeling (TUNEL) and laser scanning confocal microscopy showed characteristic apoptotic germ cells delineating the periphery of the seminiferous tubules. The ability of bis-chelated 4,7-dimethyl- and 5-dinitro-substituted 1,10-phenanthroline complexes of oxovanadium(IV) to induce germ cell apoptosis in vivo may have potential utility in the treatment of human testicular germ cell tumors.

Lack of adverse effects on fertility of female CD-1 mice exposed to repetitive intravaginal gel-microemulsion formulation of a dual-function anti-HIV agent: aryl phosphate derivative of bromo-methoxy-zidovudine (compound WHI-07)

5-bromo-6-methoxy-5,6-dihydro-3(')-azidothymidine-5(')-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), a novel bromo-methoxy-substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual-function contraceptive agent with anti-HIV activity. Its potential for reproductive toxicity was assessed in a series of experiments using CD-1 mice under the conditions of its intended use as an intravaginal microbicide. Female CD-1 mice were exposed intravaginally to a gel-microemulsion formulation containing 0%, 0.5%, 1.0% or 2.0% WHI-07 for up to 13 weeks. On a molar basis, these concentrations represent 1400-5700 times its in vitro spermicidal IC(50) and 1.4-5.7(x10(6)) times its in vitro anti-HIV IC(50). We examined the effects of intravaginally administered WHI-07 on: ovulation efficiency; in vivo fertilization and early embryonic, fetal development; and reproductive outcome, including neonatal survival and pup development. Compound WHI-07 was administered intravaginally during superovulation, organogenesis and prior to mating for 5 and 10 consecutive days and for 13 weeks, respectively. Mice were evaluated for ovulation efficiency and fertilization rate and cleavage 14 and 40 h after human chorionic gonadotropin (hCG) injection, respectively. Pregnant mice were administered 2% WHI-07 intravaginally during gestation days (GD) 6-15 and measures of teratogenicity were evaluated on GD 17. For short-term toxicity study, mice were given intravaginal treatment of gel-microemulsion containing 0%, 0.5%, 1.0% and 2.0% WHI-07 for 13 weeks and then mated with untreated males to evaluate potential reproductive and developmental effects. Repeated intravaginal exposure of mice to 2% WHI-07 had no adverse effects on ovulation response, mean number of eggs recovered or the percentage of eggs fertilized or cleaved. No evidence of reproductive toxicity, fetal toxicity or teratogenicity was found following repetitive intravaginal application of 2% WHI-07 during the period of organogenesis. Furthermore, repeated intravaginal exposure of mice to 0.5-2.0% WHI-07 for 13 weeks had no adverse effect on the subsequent reproductive capability, perinatal outcome or growth and development of the offspring. Compound WHI-07 shows unique clinical potential as a safe, dual-function vaginal contraceptive for curbing mucosal and perinatal HIV transmission.

GM-144, a novel lipophilic vaginal contraceptive gel-microemulsion

In a systematic effort to develop a dual-function intravaginal spermicide as well as a drug delivery vehicle against sexually transmitted pathogens, a submicron particle size (30-80 nm), lipophilic and spermicidal gel-microemulsion (viz GM-144) containing the pharmaceutical excipients propylene glycol, Captex 300, Cremophor EL, Phospholipon 90G, Rhodigel, Pluronic F-68, and sodium benzoate was formulated. GM-144 completely immobilized sperm in human or rabbit semen in less than 30 seconds. Therefore, the in vivo contraceptive potency of intravaginally applied GM-144 was compared in the standard rabbit model to those of the detergent spermicide, nonoxynol-9 (N-9)-containing formulation. Eighty-four ovulated New Zealand White rabbits in subgroups of 28 were artificially inseminated with and without intravaginal administration of GM-144 or 2% N-9 (Gynol II) formulation and allowed to complete term pregnancy. GM-144 showed remarkable contraceptive activity in the rigorous rabbit model. When compared with control, intravaginal administration of GM-144 and Gynol II resulted in 75% and 70.8% inhibition of fertility (P <.0001 versus control, Fisher's exact test), respectively. Thus, GM-144 as a vaginal contraceptive was as effective as the commercially available N-9 gel. In the rabbit vaginal irritation test, none of the 6 rabbits given daily intravaginal application of spermicidal GM-144 for 10 days developed epithelial ulceration, edema, leukocyte influx, or vascular congestion characteristic of inflammation (total score = 5). Therefore, GM-144 has the potential to become a clinically useful safe vaginal contraceptive and a vehicle for formulating lipophilic drugs used in reducing the risk of heterosexual transmission of sexually transmitted diseases.