Phase III trial comparing paclitaxel poliglumex vs docetaxel in the second-line treatment of non-small-cell lung cancer.

Paclitaxel poliglumex (PPX), a macromolecule drug conjugate linking paclitaxel to polyglutamic acid, reduces systemic exposure to peak concentrations of free paclitaxel. Patients with non-small-cell lung cancer (NSCLC) who had received one prior platinum-based chemotherapy received 175 or 210 mg m(-2) PPX or 75 mg m(-2) docetaxel. The study enrolled 849 previously treated NSCLC patients with advanced disease. Median survival (6.9 months in both arms, hazard ratio=1.09, P=0.257), 1-year survival (PPX=25%, docetaxel=29%, P=0.134), and time to progression (PPX=2 months, docetaxel=2.6 months, P=0.075) were similar between treatment arms. Paclitaxel poliglumex was associated with significantly less grade 3 or 4 neutropenia (P<0.001) and febrile neutropenia (P=0.006). Grade 3 or 4 neuropathy (P<0.001) was more common in the PPX arm. Patients receiving PPX had less alopecia and did not receive routine premedications. More patients discontinued due to adverse events in the PPX arm compared to the docetaxel arm (34 vs 16%, P<0.001). Paclitaxel poliglumex and docetaxel produced similar survival results but had different toxicity profiles. Compared with docetaxel, PPX had less febrile neutropenia and less alopecia, shorter infusion times, and elimination of routine use of medications to prevent hypersensitivity reactions. Paclitaxel poliglumex at a dose of 210 mg m(-2) resulted in increased neurotoxicity compared with docetaxel.

Expression of lysophosphatidic acid acyltransferase beta (LPAAT-beta) in ovarian carcinoma: correlation with tumour grading and prognosis.

Lysophosphatidic acid acyltransferase beta (LPAAT-beta) is an enzyme involved in lipid biosynthesis whose role in tumour progression has been of emerging interest in the last few years. We investigated the expression of LPAAT-beta by reverse transcriptase-polymerase chain reaction and immunohistochemistry in 10 ovarian cell lines as well as in a cohort of 106 ovarian tumours and normal ovaries. Lysophosphatidic acid acyltransferase beta mRNA was found in all cell lines and ovarian tumours examined. Expression of LPAAT-beta protein was significantly increased in ovarian carcinomas compared to benign ovarian tissue (chi2 test P-value=0.001, Kruskal-Wallis test P-value <0.0001). Furthermore, LPAAT-beta expression was positively associated with higher tumour grade (P=0.044), higher mitotic index (P<0.0001) and tumour stage (P=0.032). Expression of LPAAT-beta was significantly linked to reduced overall survival time (P=0.024) as well as to shorter progression-free survival time (P=0.012) in patients younger than 60 years. Our study shows that LPAAT-beta is upregulated in ovarian cancer and is more prevalent in poorly differentiated tumours. In addition, LPAAT-beta expression is a predictor of a worse prognosis in patients younger than 60 years. Further studies are needed to investigate if LPAAT-beta may serve as a therapeutic target for certain subgroups of patients.

Water-soluble poly-(L-glutamic acid)-Gly-camptothecin conjugates enhance camptothecin stability and efficacy in vivo.

The therapeutic efficacy of 20(s)-camptothecin (CPT) is limited in humans by the instability of the active lactone form due to preferential binding of the carboxylate to serum albumin and by difficulty in formulation. Formation of an ester bond with an amino acid via the hydroxyl group at carbon 20 of CPT stabilizes the lactone. Linking CPT to a high molecular weight (MW) anionic polymer enhances solubility and improves distribution to the tumor through enhanced permeability and retention (EPR effect). Poly-(L-glutamic acid) (PG) is an anionic homo-polymer that can theoretically bind one molecule of a drug via the gamma carboxylic acid of each monomeric subunit. It has been used to make a water-soluble PG-paclitaxel conjugate currently in Phase II clinical trials that contains 37% paclitaxel by weight and is administered in a 10 min infusion without pre-medication. We evaluated the anti-tumor activity of PG conjugates of CPT after a single intraperitoneal injection using subcutaneous murine B-16 melanoma tumor growth as an indicator. Interposition of a glycine (gly) linker allowed CPT loading up to 50% w/w on the polymer. Increasing the PG MW from 33 to 49 kDa enhanced the efficacy without altering the maximum tolerated dose (MTD). In athymic mice bearing ectopic human colon or lung tumors, efficacy was enhanced compared to free camptothecin. Thus, as with paclitaxel, conjugation of CPT to PG enhanced pharmaceutical properties and preclinical efficacy.

Pharmacological inhibition of phosphatidylcholine biosynthesis is associated with induction of phosphatidylinositol accumulation and cytolysis of neoplastic cell lines.

De novo production of phosphatidic acid (PA) in tumor cells is required for phospholipid biosynthesis and growth of tumor cells. In addition, PA production by phospholipase D has been cited among the effects of certain oncogenes and growth factors. In this report, it has been demonstrated that enhanced phospholipid metabolism through PA in tumor cells can be exploited pharmacologically for development of anticancer agents, such as CT-2584, a cancer chemotherapeutic drug candidate currently in Phase II clinical trials. By inhibiting CTP:choline-phosphate cytidylyltransferase (CT), CT-2584 caused de novo phospholipid biosynthesis via PA to be shunted away from phosphatidylcholine (PC) and into phosphatidylinositol (PI), the latter of which was doubled in a variety of CT-2584-treated tumor cell lines. In contrast, cytotoxic concentrations of cisplatin did not induce accumulation of PI, indicating that PI elevation by CT-2584 was not a general consequence of chemotherapy-induced cell death. Consistent with this mechanism of action, propranolol, an inhibitor of PA phosphohydrolase and phosphatidylcholine biosynthesis, was also cytotoxic to tumor cell lines, induced PI accumulation, and potentiated the activity of CT-2584 in cytotoxicity assays. As expected from biophysical properties of anionic phospholipids on cellular membranes, CT-2584 cytotoxicity was associated with disruption and swelling of endoplasmic reticulum and mitochondria. We conclude that CT-2584 effects a novel mechanism of cytotoxicity to cancer cells, involving a specific modulation of phospholipid metabolism.

Lisofylline suppresses ex vivo release by murine spleen cells of hematopoietic inhibitors induced by cancer chemotherapeutic agents.

Many cytotoxic cancer therapeutic drugs activate stress response signaling pathways that transcriptionally activate a variety of genes. We decided to determine if cytotoxic therapies induce inflammatory cytokines with inhibitory effects on hematopoiesis and if lisofylline (LSF), a novel antiinflammatory compound, suppresses this induction. Mice were treated with cytosine beta-d-arabinofuranoside (AraC), cis-platinum(II)diammine-dichloride (CisP), etoposide (VP-16), or melphalan at clinically relevant doses, with or without LSF. Spleen cell conditioned media (CM) derived from mice treated with cytotoxic agents, but not from control or LSF treated mice, reduced colony formation by murine bone marrow progenitors belonging to the myeloid, erythroid, megakaryocytic, and B-lymphoid lineages. LSF (100 mg/kg), administered either simultaneously with or up to 48 hours before the cytotoxic agents, suppressed the release of this inhibitory activity. Treatment of inhibitory CM with neutralizing antibodies against known growth inhibitory cytokines, including tumor necrosis factor alpha, transforming growth factor beta, and macrophage inflammatory protein-1alpha, resulted in enhanced colony growth. We conclude that treatment of mice with chemotherapeutic drugs induces the ex vivo production of multilineage hematopoietic inhibitors and that induction of these inhibitors could be abrogated by treatment with LSF. These findings suggest a mechanism whereby LSF can accelerate recovery of hematopoiesis following cytotoxic therapies.

A randomized placebo-controlled trial of lisofylline in HLA-identical, sibling-donor, allogeneic bone marrow transplant recipients. The Lisofylline Marrow Transplant Study Group.

The purpose of the study was to evaluate the effect of lisofylline (LSF) on engraftment, regimen-related toxicities (RRT), and mortality in patients undergoing allogeneic bone marrow transplantation (BMT). We performed a multicenter, randomized placebo-controlled trial in 60 patients with hematologic malignancies receiving BMT from HLA-identical sibling donors. Patients were randomized to receive either placebo, 2 mg/kg LSF or 3 mg/kg LSF every 6 h, beginning before conditioning and continuing to day 21 or hospital discharge. Treatment groups were balanced with respect to conditioning regimen and disease stage. However, significantly more patients in the 2 mg/kg LSF group were at high risk for RRT due to performance status >/=1, age >/=40 years, and prior exposure to CMV. Nausea and vomiting were the only adverse events observed in a higher proportion of LSF-treated patients that led to study withdrawal in six of 42 patients (14%). The times to neutrophil recovery to >/=500/microl and platelet recovery (>20 000/microl) were not improved by LSF treatment. Nevertheless, no patient who received treatment with 3 mg/kg LSF developed a documented infection between day 0 and 35 or had a serious or fatal infection between day 0 and 100 (P = 0.003 vs placebo for both). The day-100 survival rate was also significantly improved in the 3 mg/kg LSF group (89%), compared with either the 2 mg/kg LSF (48%) or placebo (61%) groups (log-rank test, 3 mg/kg LSF vs placebo, P = 0. 026). We conclude that treatment with LSF 3 mg/kg reduced the incidence of infections and improved 100-day survival in patients receiving related-donor allogeneic bone marrow transplantation. Bone Marrow Transplantation (2000) 25, 283-291.

Conjugation of camptothecins to poly-(L-glutamic acid).

Conjugation of water-insoluble cancer chemotherapeutic drugs to macromolecular polymers can lead to improved pharmaceutical properties and improved therapeutic ratios due to accumulation of the polymer-drug conjugate in tumor tissue through the enhanced permeability and retention (EPR) to macromolecules associated with tumor vasculature. Pharmaceutical shortcomings of certain active camptothecins including difficulty in formulation and instability of the active lactone form due to interactions with human albumin might be improved by conjugation to polymers. In this report, conjugations of camptothecin (CPT), 10-hydroxy-CPT, and 9-amino-CPT to poly-(L-glutamic acid) (PG) are described; coupling was accomplished either through the 20(S)-hydroxyl or 9 and 10 substituents with and without the use of a glycine linker. Studies using a PG paclitaxel conjugate (PG-TXL), which is currently in Phase I testing, demonstrated that PG enhanced aqueous solubility, prolonged plasma residence time, and greatly increased the distribution of paclitaxel to tumor tissue in a murine model. In this report, we describe the use of similar conjugation technology for CPT derivatives and demonstrate that these difficult to formulate compounds can be rendered water soluble, that their maximum tolerated doses are increased, and that they retain substantial anti-tumor activity in syngeneic and xenogeneic tumor models. Preliminary data suggest that PG with molecular weights between 37 and 50 kDa with CPT loading between 14% and 37% with or without glycine linkers display enhanced efficacy compared with nonconjugated camptothecins administered at their maximum tolerated dose.

Cloning and expression of two human lysophosphatidic acid acyltransferase cDNAs that enhance cytokine-induced signaling responses in cells.

Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are two phospholipids involved in signal transduction and in lipid biosynthesis in cells. LPA acyltransferase (LPAAT), also known as 1-acyl sn-glycerol-3-phosphate acetyltransferase (EC 2.3.1.51), catalyzes the conversion of LPA to PA. In this study, we describe the isolation and characterization of two human cDNAs that encode proteins possessing LPAAT activities. These two proteins, designated here as LPAAT-alpha and LPAAT-beta, contain extensive sequence sequence similarities to microbial or plant LPAAT sequences. LPAAT-alpha mRNA was detected in all tissues with highest expression in skeletal muscle whereas LPAAT-beta was expressed predominantly in heart and liver tissues. Expression of these two cDNAs in an Escherichia coli strain with a mutated LPAAT gene (plsC) complements its growth defect and shifts the equilibrium of cellular lipid content from LPA to PA and other lipids. Overexpression of these two cDNAs in mammalian cells leads to increased LPAAT activity in cell-free extracts using an in vitro assay that measures the conversion of fluorescently labeled LPA to PA. This increase in LPAAT activity correlates with enhancement of transcription and synthesis of tumor necrosis factor-alpha and interleukin-6 from cells upon stimulation with interleukin-1beta, suggesting LPAAT overexpression may amplify cellular signaling responses from cytokines.

Preferential radiosensitization of G1 checkpoint-deficient cells by methylxanthines.

PURPOSE: To develop a checkpoint-based strategy for preferential radiosensitization of human tumors with deficient and/or mutant p53. METHODS AND MATERIALS: A549 human lung adenocarcinoma cell lines differing in their expression of the p53 tumor suppressor gene were produced by transduction with the E6 oncogene from human papilloma virus type 16. The cells expressing E6 (E6+) lack a G1 arrest in response to ionizing radiation, are deficient in p53 and p21 expression, and exhibit a fivefold greater clonogenic survival following 10 Gy radiation. RESULTS: Postirradiation incubation with millimolar concentrations of the methylxanthine pentoxifylline (PTX) results in preferential radiosensitization of the E6+ cells compared to the LXSN+ vector transduced controls. There is a threefold sensitization of the LXSN+ cells and a 15-fold sensitization of the E6+ cells, which results in equal clonogenic survival of the two lines. Flow cytometry reveals PTX abrogation of the radiation induced G2 arrest for both cell lines. PTX also prolongs G1 transit for both cell lines. Preliminary results are presented using a novel methylxanthine, lisofylline (LSF), which has similar cell cycle effects on G1 and G2 and achieves differential radiosensitization at micromolar concentrations that are sustainable in humans. CONCLUSION: This checkpoint-based strategy is a promising approach for achieving preferential radiosensitization of p53- tumors relative to p53+ normal tissues.

Lisofylline inhibits transforming growth factor beta release and enhances trilineage hematopoietic recovery after 5-fluorouracil treatment in mice.

The effectiveness of endogenous or exogenously administered colony-stimulating factors may be modulated by the presence of hematopoietic inhibitory molecules. Cytotoxic therapy may result in the induction of hematopoietic inhibitors contributing to prolonged myelosuppression, whereas preventing the induction of such inhibitors may accelerate multilineage recovery. Lisofylline [LSF; (R)-1-(5-hydroxyhexyl)-3,7, dimethyl-xanthine], inhibits the signaling and/or release of certain hematopoietic inhibitory molecules such as tumor necrosis factor alpha, macrophage inflammatory protein 1 alpha, transforming growth factor beta, and IFN-gamma. Treatment of murine bone marrow cells with the cytotoxic agent 5-fluorouracil (5-FU) results in the release of a nondialyzable inhibitor of progenitor (colony-forming unit-granulocyte macrophage; CFU-GM) proliferation. When murine bone marrow cells were treated with 5-FU plus LSF, release of this inhibitor of CFU-GM proliferation was blocked. Neutralizing antibody and Western blot analysis indicated that the inhibitor was TGF-beta. We tested the effect of LSF (100 mg/kg i.p., b.i.d.) on multilineage regeneration after high-dose 5-FU or thiotepa treatment in BALB/c mice. In 4 of 5 experiments, LSF significantly accelerated neutrophil recovery (P < or = 0.05, Wilcoxon paired-signed test). In addition, platelet, reticulocyte, and CFU-GM regeneration were significantly accelerated in mice treated with LSF compared to control mice (P < or = 0.05). LSF had no significant effects on the ability of 5-FU to kill hematopoietic progenitor cells, nor did LSF stimulate or inhibit proliferation of CFU-GM. LSF had no effect on chemotherapy-induced killing of tumor cells in vitro, nor on the antitumor activity of 5-FU or thiotepa in BALB/c mice implanted with P388 leukemia cells. Inhibition of hematopoietic inhibitor release may accelerate multilineage recovery after cytotoxic therapy and, as such, may represent an alternative or additional therapy to the use of positively acting lineage specific colony-stimulating factors.

Nontransformed colony-derived stromal cell lines from normal human marrows. I. Growth requirement and myelopoiesis supportive ability.

We report a new method for generating nontransformed human stromal cell lines with a replicative potential of 20 to 25 doublings yielding 10(6) to 3 x 10(7) cells after 4 to 6 weeks. Cells from week-3 to -6 adherent layers of human long-term bone marrow cultures (LTBMC) were plated in methylcellulose in the presence of 20 U/mL interleukin-1 beta (IL-1 beta) and 200 U/mL tumor necrosis factor-alpha (TNF-alpha). After 2 to 3 weeks, we obtained 180 +/- 14 colonies per 10(5) cells seeded. These well-delineated colonies with a dense central core consisted of up to several hundred tightly packed, identical, large refractile cells. Colonies were determined to be clones by sequential examination of the cultures and the linear relationship between the number of colonies counted and cells seeded. Colony-derived cell lines (CDCL) were developed by seeding individual colonies in long-term culture medium (LTCM) supplemented with 20 ng/mL basic fibroblast growth factor (bFGF). The selection of colonies yielding lines with high proliferative capacity was due to the presence of IL-1 beta and TNF-alpha in the semisolid medium. The most effective concentrations for clonal selection were 200 U/mL TNF-alpha and 20 U/mL IL-1 beta. The growth of CDCL in liquid culture depended on the presence of bFGF, with the most effective concentration at 20 ng/mL. CDCL were able to maintain the output of colony-forming units granulocyte/macrophage and burst-forming unit-erythrocyte (CFU-GM and BFU-E) for several weeks from cocultured CD34+ marrow cells. The weekly CFU-GM and BFU-E output from weeks 2-5 was at least the same as observed when using passaged adherent layers. CDCL represent a progenitor cell population for stromal cells that may prove a suitable model for the study of the relationship between marrow stromal cells and hematopoiesis.

Phase III randomized, double-blind placebo-controlled trial of rhGM-CSF following allogeneic bone marrow transplantation.

Preliminary studies in allogeneic BMT suggest that recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is well tolerated. This is a prospective, multicenter, randomized, double-blind, placebo-controlled trial. Yeast-derived rhGM-CSF 250 micrograms/m2/day or placebo was administered by 4-hour i.v. infusion starting on the day of marrow infusion (day 0) to day 20. All patients received HLA-identical sibling marrow and cyclosporine and prednisone for GVHD prophylaxis. Fifty three patients received rhGM-CSF and 56 received placebo. Comparison of demographics revealed no differences. The time to achieve an absolute neutrophil count of > 0.5 x 10(9) cells/l was shortened in rhGM-CSF treated patients (day 13 vs. 17, P = 0.0001). The incidences of grade III-IV mucositis and infection were significantly reduced (P = 0.005, P = 0.001, respectively) and duration of hospitalization was modestly shortened by 1 day (P = 0.02) in rhGM-CSF treated patients. No differences in platelet recovery, erythrocyte recovery, incidence of veno-occlusive disease, GVHD severity, relapse or survival were observed. In conclusion, rhGM-CSF is well tolerated and reduces post-transplant morbidity in patients undergoing HLA-identical allogeneic BMT.

Potential role for phosphatidic acid in mediating the inflammatory responses to TNF alpha and IL-1 beta.

Tumor necrosis factor alpha (TNF alpha), interleukin 1 beta (IL-1 beta), and endotoxin (LPS) are potent pro-inflammatory mediators which induce multiple and diverse biological responses in a wide variety of cell types. However, these pro-inflammatory mediators also have significant overlap and redundancy in their biological effects. This suggests that there is significant diversity in second messenger signal transduction systems induced by these stimuli to explain the diversity in biological responses, as well as significant redundancy. Here we show that one such second messenger common to several proinflammatory stimuli may be phosphatidic acid (PA). Intracellular PA species, which may have intracellular signaling functions, are rapidly induced in P388 monocytic leukemia cells by TNF alpha, IL-1 beta, or LPS. These PA species vary according to the bond type (i.e., sn-1 ester vs. ether vs. vinyl ether), acyl chain length, and the degree of saturation in the sn-1 and sn-2 positions. Although PA itself may have direct second messenger activities, many of the PA species induced are converted to diacylglycerol species (DG), which are structurally distinct from the DGs generated by phosphatidylcholine-specific phospholipase C (PC-PLC). Lisofylline [(R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine; LSF] selectively inhibits generation of selected species of PA in P388 cells induced by TNF alpha, IL-1 beta or LPS. TNF alpha-induced sphingomyelin hydrolysis, PLC-mediated PC hydrolysis, and DG kinase-mediated PA formation or TNF alpha-induced NF-kappa B activation and apoptosis are not inhibited by LSF. LSF has a marked protective effect in a variety of acute inflammatory animal models that may be due to inhibition of this shared second messenger pathway involving PA.

Recombinant human granulocyte-macrophage colony-stimulating factor after autologous bone marrow transplantation for lymphoid cancer: an economic analysis of a randomised, double-blind, placebo-controlled trial.

In a blinded retrospective economic evaluation of a double-blind, randomised, placebo-controlled clinical trial, total utilisation and charges for lymphoid cancer patients who received recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or placebo were compared following autologous bone marrow transplantation. The 40 patients enrolled (22 rhGM-CSF, 18 placebo) could have acute lymphoblastic leukaemia, non-Hodgkins lymphoma or Hodgkin's disease, be of any age, and were undergoing autologous bone marrow transplantation in a metropolitan cancer research centre. Main outcome measures consisted of initial hospital lengths of stay (LOS), total and department charges, rehospitalisation rates and charges, and outpatient charges, all inclusive of the first 100 days following bone marrow infusion. The perspective of the study is that of the third party payer. Initial hospitalisation charges were $US54 100 for patients who received rhGM-CSF and $US68 600 for patients who received placebo (p = 0.05). The difference of $US14 500 was 21% less in patients who received rhGM-CSF, mainly due to lower average LOS with rhGM-CSF (24.2 days) compared with placebo (30.8 days). Outpatient charges were $US9500 (rhGM-CSF) and $US6800 (placebo) {p = 0.18}. Total charges, including readmission (10 per group) were $US12 200 lower in the rhGM-CSF group ($US70 300 vs $US82 500, p = 0.19). The use of rhGM-CSF after autologous bone marrow transplantation was shown to result in substantial cost savings during the initial hospitalisation. When comparing total inpatient and outpatient medical charges within the first 100 days following bone marrow infusion, we found no evidence that these savings were negated.

Phase I study of recombinant interleukin-1 beta in patients undergoing autologous bone marrow transplant for acute myelogenous leukemia.

A phase I trial was conducted with recombinant human interleukin-1 beta (rhIL-1 beta) in patients undergoing autologous bone marrow (BM) transplantation for acute myelogenous leukemia. rhIL-1 beta was administered at 3 dose levels (0.01, 0.02, 0.05 microgram/kg) by 30 minute intravenous infusion once a day beginning on the day of BM infusion and continuing for a total of 5 doses. A total of 17 patients were entered on the trial, and their results were compared with those of 74 consecutive historical control patients that did not receive colony stimulating factors. Moderate toxicity was observed in all patients. All 17 patients developed fever and chills within 30 minutes after initiation of rhIL-1 beta, and hypotension was observed in 14 of 17 patients 5 to 8 hours after the infusion. A total of 30% of patients required therapy (normal saline or dopamine) for treatment of hypotension. Therefore, dose escalation was discontinued at the 0.05 microgram/kg dose level. The number of days required to achieve an absolute neutrophil count greater than 500 mL in patients who received rhIL-1 beta was less than in historical patients (25 v 34; P = .02). This appeared to correlate with a reduced incidence of infection between days 0 and 28 after BM infusion (12% v 23%; P = .049). Median bilirubin, median creatinine, platelet recovery, and days in the hospital were not different between study patients and historical controls. Survival of patients who received rhIL-1 beta compared with that of historical patients was improved (30% v 20%; P = .04). These possible benefits were achieved at the cost of moderate toxicity during rhIL-1 beta administration.

CT-1501R selectively inhibits induced inflammatory monokines in human whole blood ex vivo.

The effect of (R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine (CT-1501R; the nonproprietary name for CT-1501R approved by the United States Name Council is lisofylline), an inhibitor of second messenger signaling through phosphatidic acid, on release of endogenous mediators important in the systemic inflammatory response syndrome (SIRS) was studied using the human whole blood ex vivo assay system. Human blood was stimulated with various endotoxin preparations, zymosan, or protein A, and the levels of secreted monokines were measured by enzyme-linked immunosorbent assay. CT-1501R inhibited tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), and IL-6 release in a dose-dependent manner and was active with all stimuli tested including Salmonella and Escherichia coli-derived endotoxin, endotoxin from both rough and smooth E. coli strains, as well as zymosan and protein A. CT-1501R inhibited monokine release by approximately 50% at 200 microM and 30% at 50 microM and was independent of the relative potency of stimulus. CT-1501R also inhibited IL-1 alpha or IL-1 beta induction of either TNF-alpha or IL-1 beta and inhibited the synergistic effects of stimulation with both human IL-1 beta and murine TNF-alpha on release of human TNF-alpha. Inhibition of monokine release following stimulation with monokine(s) was, in general, greater than that achieved with lipopolysaccharide (LPS) stimulation. Northern blot analysis showed decreased mRNA accumulation of TNF-alpha and IL-1 beta in CT-1501R-treated samples following LPS stimulation suggesting that CT-1501R acts at least in part, at the pretranslational level. In contrast, CT-1501R does not inhibit LPS-stimulated IL-8 or IL-1 receptor antagonist (IL-1ra) release in human whole blood or IL-1 alpha-induced release of PGE2 in human foreskin fibroblast cells. These data suggest that CT-1501R may be of use for clinical intervention in SIRS.

Protection from endotoxic shock in mice by pharmacologic inhibition of phosphatidic acid.

Certain phosphatidic/plasmanic/plasmenic acid (PA) species function as lipid intermediates in cell activation and may function directly as intracellular signaling molecules. PA can also be dephosphorylated to 1,2-diradyl-sn-glycerol by phosphatidate phosphohydrolase. Treatment of various cell types, including murine P388 monocytic leukemia cells, with bacterial lipopolysaccharide rapidly stimulates large increases in PA and PA-derived diradylglycerol. Pentoxifylline, 1-(5-oxohexyl)-3,7-dimethylxanthine, inhibits lipopolysaccharide-stimulated formation of PA in P388 cells at high concentrations (IC50 = 500 microM). Lisofylline [1-(5R-hydroxyhexyl)-3,7-dimethylxanthine] is a unique metabolite of pentoxifylline in humans and is > 800-fold more active as an inhibitor of PA formation than pentoxifylline (IC50 = 0.6 microM). Lisofylline does not inhibit lipopolysaccharide-induced activation of phosphatidylinositol-specific phospholipase C and generation of phosphatidylinositol-derived diradylglycerol. Lisofylline but not pentoxifylline protects BALB/c mice from endotoxin lethality when administered 4 hr after lipopolysaccharide. This protective effect is independent of either agent's effect on suppression of plasma tumor necrosis factor alpha. These data suggest that inhibitors of PA formation may have significant clinical potential in the treatment of sepsis and septic shock.

Differential expression of collagenase by human fibroblasts and bone marrow stromal cells.

The bone marrow stroma, represented in long-term marrow culture by cells of the adherent layer, is composed of a heterogenous mixture of macrophages and mesenchymal cells, including fibroblasts, endothelial cells and adipocytes, in association with a proteoglycan matrix. This matrix, which is synthesized by the stroma, is capable of binding hematopoietic growth factors, and likely plays a major role in hematopoietic regulation. Clonally-derived non-transformed bone marrow stromal cells, propagated in the presence of basic fibroblast growth factor, were studied for expression of collagenase, an enzyme whose substrate, collagen, is a major component of the extracellular matrix. Expression of steady-state collagenase mRNA was undetectable in both unstimulated dermal fibroblasts and non-transformed marrow stromal cells. However, stimulation with interleukin 1 alpha (10 U/ml) for 24 h resulted in marked accumulation of collagenase mRNA in dermal fibroblast cells, yet failed to elicit a similar response in bone marrow stromal cells. Both marrow stromal cells and dermal fibroblasts constitutively expressed transcripts of collagen I, and rhIL-1 alpha upregulated transcripts of interleukin 6 in both these cells as well. Although similar in morphology, these data indicate that bone marrow stromal cells differ from fibroblasts in their response to IL-1. In the marrow microenvironment, where IL-1 may be secreted by a variety of cell types, such suppression of collagenase expression may serve to prevent unwanted mobilization of collagen from the glycoprotein matrix by marrow stromal cells.

Phase I trial with recombinant human interleukin-3 in patients with lymphoma undergoing autologous bone marrow transplantation.

Recombinant human interleukin-3 (rhIL-3) was administered to 30 patients undergoing autologous bone marrow transplant (ABMT) for treatment of lymphoma. In this phase I dose escalation study, rhIL-3 was administered from day 0 to 20 after ABMT by 2-hour intravenous infusion at dose levels of 1, 2, 5, and 10 micrograms/kg/d. Seventeen patients did not complete therapy with rhIL-3. Eleven requested early discontinuation for malaise, confusion, transplant complications, or rapid engraftment and were removed from the study, whereas six patients developed grade III toxicity, including fever (three patients), or headache (three patients) possibly attributable to rhIL3. Other common toxicities included diarrhea, rigors, mucositis, and rash. The maximum tolerated dose of rhIL-3 was 2 micrograms/kg/d. No evidence of earlier hematopoietic cell recovery was observed compared with similar historical patients treated with recombinant human granulocyte-macrophage colony-stimulating factor. Future trials will be needed to determine alternate schedules of administration of rhIL-3 or the use of rhIL-3 in combination or in sequence with other growth factors.