The effect of a novel, non-steroidal anti-inflammatory compound, nabumetone (BRL 14777), on cellular infiltration into 24-hour polyvinyl sponge implants in the rat, compared with some steroidal and non-steroidal anti-inflammatory drugs

Tumorangiogenese und Immunsuppression

BACKGROUND

Angiogenesis and tumor-associated immunosuppression are two of the hallmarks of carcinogenesis. In previous studies we demonstrated in vitro that HNSCC tumor cells attract monocytes via monocyte chemotactic protein-1 (MCP-1) and activate them via transforming growth factor-beta 1(TGF-beta1) to secrete interleukin (IL)-1alpha, which in turn stimulates tumor cells to secrete increased levels of the angiogenic and immunosuppressive vascular endothelial growth factor (VEGF). These findings suggest that interaction between the immune system and VEGF-mediated angiogenesis is important for progression of HNSCC. Recent studies in vitro show that retinoic acid (RA) downregulates the release of MCP-1 and TGF-beta1 by tumor cells. Therefore, we investigated the ability of RA to modulate the ability of tumor cells to recruit and activate monocytes for participation in VEGF-mediated angiogenesis and immunosuppression in vivo.

MATERIAL AND METHODS

Mice (ten/group) were injected daily with RA (160 microg/kg) for 3 weeks. After that time mice were sacrificed, and paraffin sections of tumors were obtained and stained for VEGF-A, CD68, and PECAM (CD31) by immunohistochemistry. The lungs, liver, and myocardium were analyzed for macro- and micrometastases. The plasma protein levels of VEGF-A and MCP-1 were determined by ELISA.

RESULTS

In RA-treated mice tumors regressed completely and RA prevented metastases (p=0.00) and macrophage infiltration (p=0.007). Treated mice downregulated VEGF-A (0 pg/ml) and MCP-1 (12 pg/ml) in peripheral blood (p=0.001).

CONCLUSION

Our findings suggest a new therapeutic possibility: the development of treatment protocols that can block each of the ways in which tumors induce new blood vessel growth and immunosuppression of the host.

Effect of sulfated beta-cyclodextrin, a water soluble cycloamylose, on the promotion and/or inhibition of angiogenesis

Previous studies have reported that sulfated b b-cyclodextrin, a naturally occurring cycloamylose built up from six to eight glucopyranose units, when administered alone promotes angiogenesis, but administered with an angiostatic steroid inhibits angiogenesis in the cick embryo bioassay. In our experiments sulfated b b-cyclodextrin has been shown to possess many properties unrelated to its classical functions in the promotion and inhibition of angiogenesis that were not previously described. We studied the angiogenic and angiostatic properties of b b-cyclodextrin in a subcutaneous plastic sponge model in mice. We realized two set of experiments. In each set mice were randomized into five groups (n= 5 mice). The first group was treated with sulfated b b-cyclodextrin (200 ng), the second group was treated with sulfated b b-cyclodextrin (2000 ng), the third group received unsubstituted b b-cyclodextrin (2000 ng), the fourth group was treated with sulfated b b-cyclodextrin (20000 ng) and the last group was used as a control group. In all groups compounds were administered intraperitoneally 4 days after subcutaneous implantation of a sterile polyvinyl sponge on day 0, controls were not treated. Cyclodextrin administered alone at low drug concentration (200 ng) promoted angiogenesis and increased the development of venules in the sponge matrix. However, cyclodextrin administered at high drug concentration (2000 and 20 000 ng) reduced the vessel index in the sponge and areas of microhemorrhages were observed. From our results we propose that b b-cyclodextrin contains both a promoter and an inhibitor of angiogenesis and that the activation of both is drug concentration dependent.

Comparative effects of nabumetone, naproxen, piroxicam, and diclofenac on rat gastric irritancy following acute exposure to OTC non-steroidal anti-inflammatory agents and other gastric irritants

This study examined the relative effects of equally-effective anti-inflammatory doses of nabumetone, naproxen, piroxicam and diclofenac on gastric irritancy induced by over-the-counter (OTC) non-steroidal anti-inflammatory drugs (NSAIDs) aspirin and ibuprofen and a variety of necrotizing agents (0.6 N HCl, 0.2 N NaOH and 25% NaCl). Within one hour, aspirin 100 and 200 mg/kg and ibuprofen up to 15 mg/kg produced significant gastric mucosal injury. Aspirin 50 mg/kg produced only minimal damage that was enhanced by 5 x ID25 piroxicam and naproxen, but not by nabumetone or diclofenac. 5 x ID25 naproxen, piroxicam, and diclofenac significantly enhanced mucosal damage produced by ibuprofen 2.5 mg/kg. An equivalent anti-inflammatory dose of nabumetone failed to enhance the gastric irritancy produced by ibuprofen 2.5 mg/kg. Similarly, naproxen, piroxicam, and diclofenac enhanced the susceptibility of the gastric mucosa to the necrotizing actions of 0.6 N HCl, 0.2 N NaOH or 25% NaCl. Naproxen, piroxicam, or diclofenac are more likely than nabumetone to enhance gastric mucosal injury produced by OTC NSAIDs (aspirin and ibuprofen) or other gastric irritants.

Nabumetone: a "nonacidic" nonsteroidal antiinflammatory drug

OBJECTIVE

To review the pharmacology, pharmacokinetic disposition, dosage recommendations, adverse effects, drug interactions, and efficacy of nabumetone in patients with selected rheumatic disorders and soft-tissue injuries.

DATA SOURCES

Data from scientific literature were extracted, evaluated, and summarized for presentation. A MEDLINE search was conducted using the following indexing terms: antiinflammatory agents, nonsteroidal, nabumetone, rheumatoid arthritis (RA), and osteoarthritis (OA). Studies evaluating nabumetone reported in articles, abstracts, or proceedings involving human subjects were considered for inclusion.

STUDY SELECTION

Special consideration was given to clinical studies using double-blind, randomized, parallel, controlled designs. Studies comparing the effectiveness and safety of nabumetone with placebo and other nonsteroidal antiinflammatory drugs (NSAIDs) were included.

DATA EXTRACTION

Data from human studies published in the English language were evaluated. Trials were assessed according to study design, sample size, and description of outcomes.

DATA SYNTHESIS

Nabumetone is a nonacidic prodrug that is metabolized to an active nonsteroidal antiinflammatory moiety, 6-methoxy-2-naphthylacetic acid (6-MNA). 6-MNA is a structural analog of naproxen. Like naproxen and other NSAIDs, 6-MNA possesses analgesic, antipyretic, and antiinflammatory activity, 6-MNA has a prolonged elimination half-life, ranging from 17 to 74 hours, which allows for once-daily dosing. The efficacy of nabumetone for treating symptoms of RA and OA has been established in controlled clinical trials. Nabumetone also has been studied in ankylosing spondylitis and soft-tissue injuries. Adverse effects associated with nabumetone are similar to those associated with other NSAIDs. Gastrointestinal reactions occur most frequently in the form of abdominal pain or indigestion, nausea, or vomiting. Central nervous system adverse effects occur less frequently, and are followed in order of occurrence by rashes.

CONCLUSIONS

Nabumetone is a prodrug metabolized to an active metabolite structurally related to naproxen. Studies have demonstrated the efficacy of nabumetone, but no advantages over the many other NSAIDs now available.

A skin suction blister model in hairless rats: application to the study of anti-inflammatory and immunomodulatory drugs

A suction blister model was developed in the hairless rat, in order to study the effects of various agents on the migration of polymorphonuclear leukocytes (PMN). A standardized abrasion, a suction blister, was formed by applying negative pressure to the skin and then separating the epidermis from the dermis. A migration chamber containing serum as the chemoattractant was placed over the wound. After 6 h of migration, the cells in the chamber were harvested, counted and identified. We evaluated PMN migration after treating the animals with active compounds: niflumic acid, and anti-inflammatory drug, and RU 41740, an immunomodulator. This in vivo model provided reproducible data and could be used to study further the functional properties of PMN. In addition, because this assay can also be used in man, a drug found to be effective in the animal system could then be tested for its activity in man.

A pharmacokinetic study of the active metabolite of nabumetone in young healthy subjects and older arthritis patients

We have performed a detailed pharmacokinetic study of the plasma concentrations of the major active metabolite of nabumetone, 6-methoxy-2-naphthylacetic acid (6 MNA), attained after a single dose and during chronic administration comparing the results of a group of young healthy volunteers with those of a group of elderly arthritic patients. The latter had higher peak plasma concentrations of 6 MNA and slower rates of elimination but there is no tendency for the drug to accumulate unpredictably in the old. Disease activity also influences plasma concentration, those with more active disease, and lower serum albumin concentrations had lower AUC values.

Growth and metastasis of human tumors in nude mice following tumor-cell inoculation into a vascularized polyurethane sponge matrix

Growth and metastasis of human tumor cells in immunodeficient nude mice were improved when tumor cells were inoculated within a vascularized artificial polyurethane sponge matrix. The sponges had been implanted 7-10 days earlier and were vascularized at the time of cell injection. All cell lines tested, including colon carcinoma-derived lines from primary tumors (HT29, PT3 and PT4) or from liver metastasis (LM3), and a metastatic variant from a melanoma (MeWo-Met) grew in a high percentage (78-94%) of the inoculated sponge grafts. When growth in sponge grafts is compared with growth at a subcutaneous site, the sponge matrix appears to increase tumorigenicity, at least for some cell lines. Regular formation of metastases was observed when cells had been injected into sponges. Most metastases were found in a second sponge graft implanted at a contralateral site, but some were also found at other s.c. sites. In vivo depletion of NK cells by pre-treatment with cyclophosphamide could not further enhance the formation of metastasis. Tumor cells from fresh surgical specimens could be propagated in sponge matrix grafts and subsequently established as cell lines in tissue culture.

Nabumetone. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in rheumatic diseases

Nabumetone is a new non-steroidal anti-inflammatory drug advocated for use in the symptomatic treatment of rheumatic and inflammatory conditions. Unlike most other drugs of its class it is non-acidic and a prodrug, which after absorption forms an active metabolite. Published data suggest that nabumetone 1 to 2g daily is comparable with therapeutic dosages of aspirin, diclofenac, ibuprofen, indomethacin, naproxen and sulindac for the treatment of pain and inflammation associated with rheumatoid arthritis, osteoarthritis and acute soft tissue injuries. While nabumetone produced fewer side effects than aspirin, results have generally shown tolerability to be similar to that of other nonsteroidal anti-inflammatory drugs. If further definition of its efficacy and tolerability relative to other non-steroidal anti-inflammatory drugs confirms these initially favourable results, then nabumetone would appear to offer a useful alternative in the treatment of painful rheumatic and inflammatory conditions.

Nabumetone: a single-center three-week comparison with placebo in the treatment of rheumatoid arthritis

Forty-six patients with definite or classical rheumatoid arthritis were entered into a three-week, double-blind, randomized, parallel study of nabumetone, 1,000 mg at bedtime, compared with placebo. Fifteen nabumetone-treated and 12 placebo-treated patients were evaluated for efficacy variables including physician's opinion of rheumatoid arthritis activity, patient's opinion of rheumatoid arthritis activity, articular index, morning stiffness, 50-foot walking time, grip strength, and acetaminophen consumption. Between-group analysis of improvement over baseline was significantly (p less than 0.05) greater for nabumetone-treated patients for six of the seven variables. Nabumetone was significantly favored over placebo in three global evaluations and significantly more placebo-treated (75 percent) than nabumetone-treated (20 percent) patients withdrew from the study due to an unsatisfactory therapeutic response. Of the 38 patients receiving the study medication, 22 percent of nabumetone-treated and 5 percent of placebo-treated patients reported adverse experiences either related to treatment or for which the relationship to treatment was unknown. No patients were withdrawn from the study as a result of these experiences and no long-term sequelae or clinically significant laboratory abnormalities were reported.

Six-month multi-center study comparing nabumetone with naproxen in the treatment of osteoarthritis

This six-month, double-blind, controlled, randomized, parallel study at 13 medical centers compared the safety and efficacy of nabumetone (1,000 mg taken at bedtime) with that of naproxen (250 mg twice daily) in the treatment of osteoarthritis in symptomatic adult outpatients. Five efficacy parameters were measured: patients' assessment of overall osteoarthritis activity and pain, physicians' assessment of overall osteoarthritis activity and pain, and physicians' assessment of pain with respect to a declined activity. All 489 patients who took medication were included in the evaluation of safety, and 455 patients (227 in the nabumetone group and 228 in the naproxen group) were evaluated for efficacy. Significant improvement in all five efficacy parameters occurred in both groups. No significant differences were found between the two groups at the end of the study in any of the five efficacy parameters. Twenty-three percent of nabumetone and 17 percent of naproxen patients withdrew from the study for lack of efficacy. At least one possible or probable treatment-related adverse experience was reported for 45 percent of nabumetone-treated patients and 42 percent of those given naproxen, and in 19 percent of the nabumetone-treated and 18 percent of the naproxen-treated patients these experiences were moderate or severe. However, only 7 percent of patients in each group withdrew from the study due to adverse experiences. Nabumetone and naproxen have comparable safety and efficacy, suggesting that a single, nighttime dose of nabumetone is a convenient, effective, and safe treatment for osteoarthritis.

Leukocyte recruitment in the subcutaneous sponge implant model of acute inflammation in the rat is not mediated by leukotriene B1

The subcutaneous sponge implant model of acute inflammation in the rat has been evaluated as a suitable test system for evaluating the potential anti-inflammatory efficacy of 5-lipoxygenase inhibitors. The inflammatory parameters measured were exudate volume and leukocyte recruitment. Specific radioimmunoassays were used to measure (1) 5-lipoxygenase (LPO) and cyclo-oxygenase (CO) activity in exudate leukocytes stimulated ex vivo with A23187, and (2) the LTB4 and PGE2 content of inflammatory exudate. The NSAIDs flurbiprofen and indomethacin inhibited cell recruitment, exudate volume and CO activity with ED50S of approximately 1 mg per kg p.o. but failed to inhibit LPO activity at 10 mg per kg p.o. Nafazatrom (Bayer 6575), quercetin and NDGA, which inhibit LPO activity in vitro, were inactive against all parameters when dosed at 100 mg per kg p.o. The "mixed inhibitors" BW755C and phenidone were approximately equipotent inhibitors of LPO activity but BW755C was 10 times more potent than phenidone against CO activity. BW755C was also greater than 10 times more potent at inhibiting cell recruitment and exudate volume than phenidone suggesting that the anti-inflammatory efficacy of the mixed inhibitors reflect their potency against CO rather than LPO activity. Time course studies demonstrated that the inhibitor effects of BW755C and phenidone on leukocyte recruitment reflected a reduction in the PGE2 but not the LTB4 content of the inflammatory exudate. Polyester sponges soaked in high concentrations of LTB4 caused only a modest (2-fold) increase in leukocyte recruitment whilst physiological levels were inactive. The results taken together suggest that CO products make a major contribution to leukocyte recruitment in this model whilst the LPO product LTB4 has little role. This model therefore is of little value for evaluating the anti-inflammatory efficacy of 5-lipoxygenase inhibitors. Moreover, the rat would appear to be unsuitable for evaluating the role of LTB4 in acute inflammation.

The effect of anti-inflammatory and anti-rheumatic drugs on cell accumulation onto nitrocellulose discs implanted subcutaneously into mice

Nitrocellulose discs were implanted subcutaneously into mice and cell accumulation measured 96 hours later. Cell accumulation was inhibited by the anti-inflammatory steroids hydrocortisone, dexamethasone and triamcinolone acetonide, but higher doses of the latter two compounds were required than are normally used in rat models of inflammation. Cell accumulation was not inhibited by the cyclo-oxygenase inhibitors naproxen, indomethacin, tolmetin or aspirin, nor by the dual cyclo-oxygenase and lipoxygenase inhibitors BW 755C and benoxaprofen. Anti-rheumatic drugs such as D-penicillamine, dapsone and colchicine and the metal chelator 1,10 phenanthroline were all inactive on cell accumulation in this model.