A phase I pharmacokinetic and safety analysis of epothilone folate (BMS-753493), a folate receptor targeted chemotherapeutic agent in humans with advanced solid tumors.

Background The folate receptor alpha is selectively over-expressed in a number of human cancers. BMS-753493 is a folate conjugate of the epothilone analog BMS-748285 that was designed to selectively target folate receptor expressing cancer cells. Methods BMS-753493 was investigated in two parallel multi-institutional first-in-human phase I/IIa studies in patients with advanced solid tumors. In Study 1, patients were treated on a schedule of once daily dosing of BMS-753493 administered on Days 1, 4, 8 and 11 every 21 days with a starting dose of 5 mg daily and in Study 2, patients were treated once daily on Days 1-4 every 21 days, with a starting dose of 2.5 mg daily. Results A total of 65 patients were treated across the two studies. The maximum tolerated dose (MTD) was 26 mg in Study 1 and 15 mg in Study 2. Fatigue, transaminitis, gastrointestinal toxicity, and mucositis were dose-limiting toxicities. One patient in Study 2 developed Stevens-Johnson syndrome attributed to BMS-753493. Plasma exposures of both the conjugated and free epothilone increased in a dose related fashion in both studies and the half-life of the conjugated epothilone was 0.2-0.6 h across dose levels. No objective tumor responses were seen in either study. Conclusions BMS-753493 was generally tolerable and toxicities known to be associated with epothilone class of anticancer agents were common, although peripheral neuropathy and neutropenia appear to have been less frequent and less severe as compared to epothilones. Antitumor activity was not demonstrated and further development of BMS-753493 has been discontinued.

Tenidap inhibits replication of the human immunodeficiency virus-1 in cultured cells.

Interleukin-6 (IL-6) may be important in the pathogenesis of HIV-1 because of its ability to induce HIV-1 expression in infected cells in vitro. Tenidap, a structurally and functionally novel antirheumatic drug affecting diverse biologic processes, has been shown to reduce IL-6 production by peripheral blood mononuclear cells stimulated with lipopolysaccharide. Tenidap also inhibits the activity of chloride-bicarbonate exchangers and causes acidification of the cytoplasmic compartment that is similar to the effect of the anion transport inhibitor UK5099. Furthermore, tenidap inhibits the cyclooxygenase-mediated pathway of arachidonic acid metabolism as do the nonsteroidal antiinflammatory drugs (NSAIDs). Here we show that tenidap decreased HIV-1 replication as measured by p24 core antigen in the acutely infected CD4+ T-lymphocyte lines H9 and Jurkat, in the acutely infected monocyte line U937, and in its chronically infected subclone U1.8/HIV. These effects were seen at concentrations in the range of 3 to 15 microM, well below those toxic to cells. The antiviral effects of tenidap may be independent of its ability to reduce IL-6 production based on the observations that these effects were as prominent in IL-6 nonresponsive lines as in IL-6 responsive lines and that the inhibition of p24 production was not reversed by exogenous IL-6.

A Tat-induced auto-up-regulatory loop for superactivation of the human immunodeficiency virus type 1 promoter.

The virus-encoded Tat protein strongly activates transcription of human immunodeficiency virus (HIV). A well-recognized mechanism involves interaction of Tat with the nascent RNA transcript of the viral tar gene; mutation of tar greatly decreases activation by Tat. However, Tat still provides a low level of activation, demonstrating that it also has a tar-independent mode of action. We propose that this tar-independent mode of Tat action is through activation of gene transcription to produce tumor necrosis factor alpha. This cytokine and other compounds that activate NF-kappa B up-regulate the HIV promoter at a low level, similarly to the second Tat action. Through this mechanism, they also activate promoters of tumor necrosis factor alpha and other cytokines and thereby establish an auto-up-regulatory loop. Activated NF-kappa B motifs in the HIV promoter synergize with Tat/tar. Mutations of these motifs decrease activation by Tat to a few percent of the wild-type value. In cooperation, the two modes of activation by Tat (tar dependent and cytokine based) set up positive up-regulatory loops which greatly superactivate transcription of HIV. Agents that block these synergistic pathways at three different steps and are more inhibitory in combination than is any one alone have been found. Thereby, multidrug modalities for transcription of HIV are proposed for virus suppression.

High-dose pentoxifylline in patients with AIDS: inhibition of tumor necrosis factor production. National Institute of Allergy and Infectious Diseases AIDS Clinical Trials Group.

Tumor necrosis factor-alpha (TNF) may activate human immunodeficiency virus (HIV), antagonize zidovudine activity, and contribute to AIDS wasting syndrome. Pentoxifylline decreases TNF production. In cell culture, pentoxifylline decreases HIV replication and gene expression. Since an AIDS Clinical Trial Group study suggested that pentoxifylline (400 mg thrice daily) is safe in AIDS patients and decreases TNF mRNA levels in peripheral blood mononuclear cells (PBMC), a second cohort received 800 mg thrice daily for 8 weeks. During treatment, the median decrease in TNF production by PBMC cultured with 0.1 microgram/mL lipopolysaccharide (LPS) was 40%. The median change in TNF mRNA was a 34% decrease. Pentoxifylline did not affect HIV levels as detected by quantitative microculture or serum p24 antigen measurements, nor did it alter zidovudine pharmacokinetics. The most common toxicity was gastrointestinal. Pentoxifylline at dosages of less than thrice-daily 800 mg is well tolerated and may decrease TNF mRNA levels and LPS-induced TNF production.

Pentoxifylline and other protein kinase C inhibitors down-regulate HIV-LTR NF-kappa B induced gene expression.

BACKGROUND: This investigation deals with the molecular mechanism of anti-human immunodeficiency virus type 1 (HIV-1) action of pentoxifylline (PTX) [1-(5'-oxohexyl)-3, 7-dimethylxanthine] a drug widely used for the treatment of conditions involving defective regional microcirculation. MATERIALS AND METHODS: The inhibition by PTX of protein kinase C (PKC) or cAMP-dependent protein kinase (PKA)-mediated activation by phorbol ester (PMA) and tumor necrosis factor alpha (TNF-alpha) of HIV-1-LTR-regulated reporter gene expression was studied in human CD4+ T lymphocytes (Jurkat) and human embryo kidney cells (293-27-2). A protein kinase C is involved in activation of NF-kappa B in whole cells, identified by using inhibitors specific for PKC- or PKA-catalyzed NF-kappa B activation in whole cell and cell-free systems. RESULTS: PTX inhibited PKC- or PKA-catalyzed activation of NF-kappa B in cytoplasmic extracts from unstimulated Jurkat or 293-27-2 cells, but not interaction of preactivated NF-kappa B with its motifs. Calphostin C, a specific inhibitor of PKC, inhibited NF-kappa B activation and HIV-1 LTR-driven reporter gene expression in both PMA- and TNF-alpha-treated cells. In contrast, although H88 specifically inhibited PKA activity in the cell-free extract, it did not affect NF-kappa B action in PMA- or TNF-alpha-treated cells. CONCLUSIONS: The mechanism of inhibitory action of PTX on virus replication and NF-kappa B-induced transactivation of HIV-1 gene expression has been elucidated as due to blocking PKC-dependent PMA- or TNF-alpha-induced activation of NF-kappa B in Jurkat and 293-27-2 cells. Other protein kinase inhibitors may be useful in down regulating transcription of HIV-1 provirus and thereby virus replication in HIV-infected patients.

Inhibitors of HIV-1 transcription.

No curative drug against HIV has yet been found, despite enormous efforts aimed at reverse transcriptase and a variety of other targets. The long terminal repeat (LTR) of HIV-1 has recently become a promising site for antiviral action. This article briefly summarizes information on the nature of this target and potential anti-LTR expression drugs.

Cooperative inhibition of NF-kappa B and Tat-induced superactivation of human immunodeficiency virus type 1 long terminal repeat.

Human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR)-regulated gene expression is stimulated independently by the cellular trans-activator NF-kappa B and the viral protein Tat. Noncytotoxic concentrations of the drug pentoxifylline (PTX) inhibited interaction of NF-kappa B with its motif and the stimulation of HIV-1 LTR-driven gene expression in Jurkat cells. Tat protein (from a cotransfected Tat-expression vector) also induced activation of HIV-1 LTR-driven gene expression. This activation was unaffected by PTX when NF-kappa B sites in the HIV-1 LTR were mutated, suggesting that this drug does not directly influence Tat function, which, however, was inhibited by the Tat-inhibitor Ro 24-7429. Transient reporter gene expression regulated by HIV-1 LTR with wild-type NF-kappa B motifs in the presence of Tat protein was 10- to 60-fold higher than in the presence of either of the trans-activators alone, demonstrating superactivation of HIV-1 LTR by the concerted action of both the trans-activators. Treatment of cells with either PTX or Ro 24-7429 inhibited this superactivation of the HIV-1 LTR. The inhibitory effect of these two drugs in combination, at concentrations that alone did not significantly influence viral promoter activity, was far more than additive. A cooperative action of PTX (NF-kappa B inhibitor) and Ro 24-7429 (Tat inhibitor) on HIV-1 LTR-regulated gene expression is suggested. Concentrations of the drugs that induced maximum inhibition of HIV-1 LTR through their cooperative action are far below cytotoxic levels. Thus, the combination of these two inhibitors could be very effective for anti-HIV therapy.

Pentoxifylline inhibits HIV-1 LTR-driven gene expression by blocking NF-kappa B action.

The drug pentoxifylline (PTX) (1-(5'-oxohexyl) 3,7-dimethylxanthine) down-regulates human immunodeficiency virus (HIV-1) long terminal repeat (LTR)-directed gene expression in the human monocytic cell line U38. This effect of PTX has been tested in clinical trials. In this investigation, a similar inhibitory effect of PTX on HIV-1 LTR-driven gene expression was observed (a) in a stable transfectant of the human embryo kidney cell line 293-27-2 carrying an expression plasmid construct with the HIV-1 LTR fused to the bacterial lac Z gene, and also (b) by transient transfection of human embryo kidney cells 293 S with fusion plasmid constructs with wild-type [pHIV-LTR-chloramphenicol acetyltransferase (CAT)] or mutated (pHIV-LTR-mut-CAT) nuclear factor kappa B (NF-kappa B) motifs. In both stable and transient transfection studies, 4-beta-phorbol-12-beta-myristate-acetate (PMA)-induced or tumor necrosis factor-alpha (TNF-alpha)-induced activation of the HIV-1 LTR was correlated with a concomitant elevated level of NF-kappa B interaction with its motifs. The inducibility of HIV-1 LTR-driven gene expression by PMA or TNF-alpha in transiently transfected cells was completely eliminated by point mutations in the NF-kappa B motifs, suggesting that NF-kappa B plays a major role in the activation of the HIV-1 LTR by these agents in this cell system.(ABSTRACT TRUNCATED AT 250 WORDS)

Pentoxifylline decreases tumor necrosis factor expression and serum triglycerides in people with AIDS. NIAID AIDS Clinical Trials Group.

Tumor necrosis factor-alpha (TNF)-cachectin increases the expression of the human immunodeficiency virus (HIV), reverses the therapeutic efficacy of zidovudine (ZDV), and may contribute to the wasting syndrome. Pentoxifylline (Trental) decreases TNF activity; in cell culture, it decreases HIV replication and down-regulates expression of the HIV long terminal repeat (LTR). Therefore, pentoxifylline was administered to 25 patients with advanced AIDS in this AIDS Clinical Trial Group study (ACTG #160), the goal of which was to investigate the ability of the drug to decrease TNF expression and HIV replication in this patient population. One patient discontinued drug treatment because of toxicity. Data were analyzed on the 17 patients who completed the 8-week study treatment with pentoxifylline, 400 mg, thrice daily. The median pretreatment CD4+ lymphocyte count was 32 cells/mm3. Fasting serum triglycerides, which have previously been shown to correlate with levels of interferon-alpha and/or TNF, fell on average by 66 mg/dl (p = 0.06). TNF mRNA levels in peripheral blood mononuclear cells fell in 10 of 16 patients (p = 0.02). HIV load decreased and increased significantly in four and one patients, respectively, but did not change in the group as a whole. This study demonstrates the safety of pentoxifylline in AIDS patients and its ability to decrease triglycerides and TNF mRNA levels.

Cytokine dysregulation in AIDS: in vivo overexpression of mRNA of tumor necrosis factor-alpha and its correlation with that of the inflammatory cytokine GRO.

The human immunodeficiency virus establishes an intimate interaction with the immune system. The virus can use cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (Il-1), to regulate its own expression by modifying the normal immunoregulatory network. We demonstrate that mRNA of the cytokine TNF-alpha from peripheral blood mononuclear cells is overexpressed in virtually all patients with AIDS who do not have active opportunistic infections compared with uninfected volunteers (p < 0.0001). This overexpression correlates with elevated mRNA levels of the recently discovered GRO (p < 0.05), a cytokine involved in the inflammatory response.