Marimastat in recurrent colorectal cancer: exploratory evaluation of biological activity by measurement of carcinoembryonic antigen

Novel Matrix Metalloproteinase-9 (MMP-9) Inhibitors in Cancer Treatment

Matrix metalloproteinases (MMPs) belong to a family of zinc-dependent proteolytic metalloenzymes. MMP-9, a member of the gelatinase B family, is characterized as one of the most intricate MMPs. The crucial involvement of MMP-9 in extracellular matrix (ECM) remodeling underscores its significant correlation with each stage of cancer pathogenesis and progression. The design and synthesis of MMP-9 inhibitors is a potentially attractive research area. Unfortunately, to date, there is no effective MMP-9 inhibitor that passes the clinical trials and is approved by the FDA. This review primarily focuses on exploring the diverse strategies employed in the design and advancement of MMP-9 inhibitors, along with their anticancer effects and selectivity. To illuminate the essential structural characteristics necessary for the future design of novel MMP-9 inhibitors, the current narrative review highlights several recently discovered MMP-9 inhibitors exhibiting notable selectivity and potency.

Targeting angiogenesis for treatment of human cancer

Recent advances in cancer research highlighted the importance of target-specific drug discovery. In view of these advances, the most important mechanism in tumour growth is its ability to stimulate the formation of blood capillaries around itself called tumour-driven angiogenesis. Hence targeting the angiogenesis, inhibits the growth of blood vessels around it and responsible for death of the tumour due to starvation and accumulation of toxic waste. The therapy, thus, indirectly cytotoxic to the tumour cells by targeting newly developing blood vessels. In this review, we summarised the various antiangiogenic agents with their clinical uses and current status.

Phase 1/2 trial of BMS-275291 in patients with human immunodeficiency virus-related Kaposi sarcoma: a multicenter trial of the AIDS Malignancy Consortium

BACKGROUND

Matrix metalloproteinases (MMPs) are overexpressed in Kaposi sarcoma (KS). The safety and efficacy of a novel, orally bioavailable MMP inhibitor, BMS-275291, was evaluated in patients with human immunodeficiency virus-associated KS and the correlation between changes in the percentage of apoptotic cells in tumor biopsies and response was explored.

METHODS

Cohorts of 6 patients were to be treated with BMS-275291. The initial cohort received 1200 mg once a day; subsequent doses were to be escalated to 600 mg twice daily and 1200 mg twice daily, or decreased to 600 mg/day. Tumor biopsies for apoptosis assays were collected pretreatment and on Day 29. Prospectively defined dose level adjustments were to be based on dose-limiting toxicity (DLT), tolerability, changes in the percentage of apoptotic cells, and treatment response.

RESULTS

Sixteen patients were enrolled; 15 received the study drug and could be evaluated. The median duration of treatment was 20 weeks (range, 3-54 weeks). A dose of 1200 mg once a day was well tolerated but induced only 1 response. A DLT occurred in 3 patients treated with 600 mg twice daily, and included grade 3 fatigue, grade 3 allergic reaction, and grade 3 arthralgias; 2 responses were noted at this dose level (toxicity was graded according to the National Cancer Institute Common Toxicity Criteria [version 2.0]). Based on predetermined endpoints, the trial was closed after accrual of 15 treated patients. Assessment of biologic response for dose escalation/de-escalation decisions utilizing the apoptosis assay was not feasible.

CONCLUSIONS

BMS-275291 given at a dose of 600 mg twice daily induced unacceptable toxicity. The better-tolerated schedule of 1200 mg once a day demonstrated inadequate efficacy in patients with human immunodeficiency virus-associated KS. The apoptosis assay was not helpful in predicting response.

Beyond 5-fluorouracil: new horizons in systemic therapy for advanced colorectal cancer

Worldwide, colorectal cancer is a common cancer and a major cause of morbidity and mortality. Patients frequently present with, or later develop, metastatic disease. Median survival with supportive care alone is approximately 6 - 8 months. However, a number of recent developments have greatly increased the range of therapeutic options, improving median survival to > 20 months. Cytotoxic agents such as capecitabine, irinotecan and oxaliplatin are now established treatment strategies. In parallel, an improved understanding of tumour biology has led to the development of non-cytotoxic targeted therapies. Examples include bevacizumab (targeting tumour angiogenesis) and cetuximab (targeting the epidermal growth factor receptor). These agents have recently been incorporated into standard management. This paper reviews these and other advances in the care of patients with advanced colorectal cancer and discusses a number of agents that are currently under development.

Radiation induced MMP expression from rectal cancer is short lived but contributes to in vitro invasion

AIMS

Matrix metalloproteinase (MMP) activity is increased after radiation. The aims of this study were to assess the time course of this increase and its effects on malignant cell invasion.

METHODS

Colorectal cancer (HCT 116, LoVo, C 170 HM 2, CaCO-2), fibroblast (46-BR.IGI, CCD-18 Co) and fibrosarcoma (HT1080) cell lines were irradiated at 4 gray (4 Gy) and matrix metalloproteinase gene and protein expression examined over a 96 h period by real time polymerase chain reaction and gelatin zymography. Invasion was assessed on Matrigel. Human rectal tumour MMP expression was compared before and after long course radiotherapy.

RESULTS

Radiation increased MMP gene expression of tumour cell lines, and resulted in increased MMP protein activity in the HT1080 line. HT1080 and HCT 116 in monoculture and LoVo in co-culture were more invasive after radiation at 48 h in vitro, but long course radiotherapy did not result in a consistent increase in MMP expression from human rectal tumour biopsies.

CONCLUSIONS

Radiation results in increased MMP expression for a limited time period. This results in an early increase in cell line invasion. Further clinical research is required to clarify if MMP inhibition given perioperatively following radiotherapy decreases local recurrence rates.

Marimastat in the treatment of patients with biochemically relapsed prostate cancer: a prospective randomized, double-blind, phase I/II trial

PURPOSE

To evaluate the safety and biological activity of three different doses of marimastat given for 6 months to patients with biochemically relapsed prostate cancer.

EXPERIMENTAL DESIGN

Patients with a biochemical relapse within 2 years of primary therapy, a prostate-specific antigen (PSA) increase of at least 50% within 6 months of study entry, and no prior systemic therapy were eligible. Patients were randomized to receive marimastat at total daily doses of 5, 20, or 40 mg for 6 months unless dose-limiting toxicity or new evidence of disease occurred.

RESULTS

Thirty-nine patients were treated. Grade 3-4 reversible musculoskeletal toxicity was the only dose-limiting toxicity. Increasing dose was associated with increased probability of experiencing dose-limiting toxicity (5.9%, 42.9% and 88.9% for the 5, 20, and 40 mg groups, respectively; P = 0.03). Accrual was discontinued early on the two higher dose levels due to toxicity. A significant decrease in PSA slope was shown in the 20 mg group when compared with the 5 mg group (0.117 and -0.0046, respectively; P = 0.03) The 40 mg group (versus the 5 mg group) showed a similar change (0.109) with a trend towards significance (P = 0.07). An increased serum matrix metalloproteinase 2 level at month 3 compared with the baseline correlated with a decrease in PSA slopes (Slope, 0.001; 95% confidence interval, 0.0002-0.0018; P = 0.02).

CONCLUSION

These data suggest that marimastat has a biological effect and may effectively delay progression in patients with biochemical relapsed prostate cancer, as shown by the change in PSA slope; however, dose-limiting toxicity at active doses is significant. Confirmatory studies with less toxic matrix metalloproteinase inhibitors employing more conventional end points are indicated. This design is feasible and potentially efficient for screening antimetastatic agents.

Novel therapeutics in colorectal cancer

Colorectal cancer is an excellent tumor model for evaluating novel therapeutic strategies. Development of a mechanistic understanding of how this cancer develops, spreads, and grows allows a tailored approach to all stages of treatment: prevention, adjuvant treatment, and therapy of advanced disease. We focus on therapy in the advanced disease setting, although progress in this area could lend itself to treatment of early or premalignant disease. In the last 20 years, information has been generated about the intracellular pathways of tumor formation, invasion, and metastasis. As a result, specific molecular processes have been targeted for therapeutic intervention, including cell surface growth factor receptors, proliferation signaling, cell cycling, apo-ptosis, angiogenesis, and matrix metalloproteinases. We review the scientific rationale for recently developed novel therapeutics in colorectal cancer, and the results of clinical trials to date. We also suggest appropriate clinical settings for specific targets and outline future directions of research.

Efficacy of the MMP inhibitor MMI270 against lung metastasis following removal of orthotopically transplanted human colon cancer in rat

We have investigated the antitumor effects of synthetic MMP inhibitor MMI270 against postoperative lung metastasis from colon cancer in nude rat. The KM12SM human colon cancer cells were injected into the cecal wall, and at 5 weeks after the injection, the cecum was removed including the tumor. Then, 30 mg/kg of MMI270 was administered perorally twice per day for 2 or 4 weeks, either immediately after removal or after week 2 after the removal. At week 7 after the removal, lung metastasis was significantly inhibited by the early administration of MMI270 immediately after the tumor removal but not by the late administration. The survival rates were significantly higher in the rats treated by early administration of MMI270 compared to the survival rate in untreated rats. Moreover, no lung metastasis was detected in some rats with 24-weeks' survival treated by early administration. Lower microvessel density, lower PCNA Index and higher Apoptotic Index in the lung metastases of the rats treated with MMI270 were found compared to those in untreated rats. A beneficial effect of by early administration of MMI270 against postoperative lung metastases may be expected through inhibiting neovascularization of metastases in nude rat.

Antiangiogenic strategies, compounds, and early clinical results in breast cancer

Angiogenesis is a multi-step process leading to the formation of new blood vessels from pre-existing vasculature and it is necessary for primary tumor growth, invasiveness and development of metastasis. Experimental and clinical data demonstrated that breast cancer is an angiogenesis-dependent disease and that the vascular endothelial growth factor (VEGF) family plays a key role it being a highly expressed and selective endothelial cell growth factor. Preclinical studies have shown that the angiogenic switch occurs early in the multistage process of breast cancer development. Targeting the molecular pathways involved in tumor progression by biologically-designed treatments is a new therapeutic paradigm aimed to reach cancer growth control. A number of possible therapeutic targets for antiangiogenic agents have been identified. Here we discuss the therapeutic approach based on inhibition of angiogenesis in the context of breast cancer with a focus on the early clinical studies on antiangiogenic agents in advanced disease.

A dose-finding and pharmacokinetic study of the matrix metalloproteinase inhibitor MMI270 (previously termed CGS27023A) with 5-FU and folinic acid

The orally bioavailable matrix metalloproteinase inhibitor MMI270 reduces tumour growth metastasis in preclinical models. We assessed the feasibility and pharmacokinetic interactions of combining MMI270 with 5-fluorouracil (5-FU) and folinic acid (FA). Entered into the study were 33 patients with advanced colorectal cancer. They received FA 200 mg/m2 over 2 h followed by 5-FU 400 mg/m2 over 15 min and 5-FU 600 mg/m2 over 22 h on days 1 and 2 of a 14-day cycle. MMI270 commenced with the second cycle at either 50 mg once daily, 150 mg three times daily or 300 mg twice daily. No dose-limiting toxicity was observed at any MMI270 dose level. Ten patients (61%) experienced joint symptoms independent of MMI270 dose, leading to interruption, modification, or discontinuation of treatment in seven patients (23%). MMI270 did not alter 5-FU pharmacokinetics. Six patients had a partial response and seven had stable disease. 5-FU/FA with MMI270 at a dose of 300 mg twice daily is well tolerated. MMI270 has no significant effect on 5-FU pharmacokinetics.

Inhibition of angiogenesis as a therapeutic strategy against brain tumors

Multidisciplinary treatment strategies for patients with malignant brain tumors have resulted in only small gains in terms of prognosis in spite of the use of aggressive therapy. There is a growing realization that a paradigm shift is needed in the conceptual approaches to glioma therapy. Such approaches will rely on identification and modification of key cellular targets that define the biological behavior of these tumors. Among the targets for such treatment approaches, tumor angiogenesis has captured the attention of not only the medical field but also of the lay public because of its conceptual departure from traditional methods of cancer therapy. Angiogenesis and vascular proliferation are particularly important in the growth and progression of malignant gliomas and are used as indicators of the degree of malignancy. Recent studies have helped us gain a better understanding of the molecular mediators of this process. It is now evident that after the initial formation of malignancy the continued growth of a glioma is critically dependent on its angiogenic potential. Hence, several approaches to control angiogenesis are being developed and tested. Preliminary results from clinical studies have shown that angiogenesis inhibition is a valid approach as a therapeutic strategy against gliomas but it is also becoming evident that inhibition of individual modulators of this process may not yield the expected impact on prognosis. To fully realize the potential of antiangiogenic therapy, a deeper understanding of the interplay between the tumor vasculature and its environment is needed. Angiogenesis inhibitors have made the transition from preclinical studies to the clinical arena; it remains for ongoing human trials of such agents to fully explore the feasibility and efficacy of these agents in order to exploit the potential of this approach.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

In vitro and in vivo endochondral bone formation models allow identification of anti-angiogenic compounds

A major obstacle in the study of angiogenesis and the testing of new agents with anti-angiogenic potential has been the lack of experimental models with predictive in vivo value. We describe here the combined use of in vitro and in vivo angiogenesis models that are based on endochondral bone development. This approach led to the identification of a new inhibitor of matrix metalloprotease (MMP) activity that inhibits neovascularization in vitro and in vivo while osteoclast invasion, which occurs simultaneously during bone development, remained unaffected. In contrast, the broad-spectrum MMP-inhibitor marimastat inhibited both in vitro angiogenesis and osteoclastogenesis dose-dependently but displayed severe toxic side effects in vivo. The combined use of these experimental models may, therefore, facilitate the discovery of mechanisms underlying angiogenesis and lead to identification of new pharmacological compounds with clinical efficacy and appropriate selectivity in the treatment of angiogenesis-dependent disorders like arthritis and cancer.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

The interaction of metal ions and Marimastat with matrix metalloproteinase 9

The effect of a range of metal ions on the ability of Marimastat to inhibit matrix metalloproteinase 9 (MMP-9) was examined in a fluorescence based proteolytic assay. Whilst none of the metals examined significantly affected the inhibitory ability of Marimastat, several metal ions did have a significant effect on MMP-9 activity itself. In the absence of Marimastat, Zn(II) and Fe(II) significantly inhibited MMP-9 activity at metal ion concentrations of 10 and 100 microM, respectively. In both the absence and presence of Marimastat, Cd(II) significantly inhibited MMP-9 at 100 microM. In contrast, 1 mM Co(II) significantly upregulated MMP-9 proteolytic activity.

Angiogenesis and hepatic colorectal metastases

Angiogenesis is a critical step in the metastatic cascade of colorectal cancer. Several angiogenesis inhibitors have been evaluated in animal models and have shown efficacy, but challenges remain in using these drugs effectively in the clinical setting. Although several of these angiogenesis inhibitors are currently being evaluated in clinical trials, alone or in combination with cytotoxic chemotherapy, early results suggest that angiogenesis inhibitors alone, when used for advanced disease, have minimal activity. It is likely that this class of drugs will prove more efficacious when used either in the setting of minimal disease as agents that may promote tumor dormancy or in combination with other conventional forms of therapy. In addition, strategies such as metronomic therapy have been proposed whereby lower doses of cytotoxic chemotherapy, given more frequently, may act via an antiangiogenic mechanism [67,68]. Another challenge is identifying methods of assessing response to antiangiogenic therapy. To date, traditional methods of identifying response to treatment have not proven effective. Several investigators are working toward identifying circulating endothelial or tumor-associated factors that may be useful in following treatment. Novel imaging techniques are also being evaluated with enhanced CT and MRI, and newer modalities. Hepatic colorectal metastases provide an opportune setting in which to accomplish these challenges because the high incidence of disease and the ability to measure tumor with a variety of techniques lend themselves to evaluation of antiangiogenic therapy.

Inhibition of cervical lymph node metastasis by marimastat (BB-2516) in an orthotopic oral squamous cell carcinoma implantation model

Activation of matrix metalloproteinase-2 (MMP-2) is a common event in head and neck squamous cell carcinoma. An OSC-19 cell line, derived from human oral squamous cell carcinoma and known to metastasize to cervical lymph nodes, was implanted into the lingual margin of mice. The effect of marimastat (BB-2516), a broad MMP inhibitor, on the suppression of regional cervical lymph node metastasis was evaluated with an orthotopic implantation nude mice model. Marimastat was given immediately after OSC-19 implantation and continuously administered by an osmotic pump. The mice were divided into three groups by marimastat dose; Group A; 0 mg/kg/day, Group B; 30 mg/kg/day, and Group C; 150 mg/kg/day. Twenty-one days after implantation, primary oral tumors and cervical lymph nodes were resected. Cervical lymph node status was microscopically examined. Activation of MMP-2 in primary oral tumor was examined by gelatin zymography. Both cervical lymph node metastasis and activation of MMP-2 were significantly suppressed in Group C (P < 0.05). Moreover, the Group C mice had a significantly better survival than group A (P = 0.0026). There was a significant difference between Group A and Group C in terms of proliferation of tumor cells by proliferating cell nuclear antigen immunostaining (P = 0.0120). These results suggest a positive role for marimastat in the inhibition of MMP-2 activation and prevention of cervical lymph node metastasis in oral squamous cell carcinoma (OSCC). Improvement of survival in patients with OSCC could be expected using adjuvant therapy with marimastat.

Development of matrix metalloproteinase inhibitors in cancer therapy

The matrix metalloproteinases represent an attractive target for cancer treatment, and a number of matrix metalloproteinase inhibitors are undergoing clinical trials. The results of these studies will establish whether any of these compounds are therapeutically useful. Independent of the conclusions from the first generation of studies, the field of matrix metalloproteinase inhibitors remains attractive for creative and innovative research. In the future, the development of novel, less toxic, and more effective matrix metalloproteinase inhibitors, and the combination of conventional agents with these novel anticancer agents will constitute the main focus of research efforts.

A randomized phase II pilot trial of adjuvant marimastat in patients with early-stage breast cancer

BACKGROUND

This pilot trial was performed to evaluate the safety, toxicity and pharmacokinetics of chronic therapy with the matrix metalloproteinase inhibitor marimastat in the adjuvant treatment of breast cancer.

PATIENTS AND METHODS

Patients with high-risk node negative or node positive breast cancer received marimastat either 5 or 10 mg p.o. b.i.d. for 12 months. Marimastat was given either as a single agent following completion of adjuvant chemotherapy or concurrently with tamoxifen.

RESULTS

Sixty-three patients were enrolled from June 1997 to May 1998. All patients have completed 12 months of treatment or have discontinued therapy due to toxicity, relapse or intercurrent illness. Moderate (WHO criteria) arthralgia/arthritis was reported by 34% of patients receiving 5 mg b.i.d. and 45% of patients receiving 10 mg b.i.d.; severe arthralgia/arthritis was reported by 6% and 23% of patients, respectively. Six patients (19%) receiving 5 mg b.i.d. and 11 (35%) receiving 10 mg b.i.d. discontinued marimastat therapy due to toxicity. Trough plasma levels were rarely within the target range for biological activity (40-200 ng/ml) with mean concentration for patients receiving: 5 mg b.i.d. = 7.5; 5 mg b.i.d. plus tamoxifen = 6.9; 10 mg b.i.d. = 11.9; 10 mg b.i.d. plus tamoxifen = 12.8.

CONCLUSIONS

A randomized adjuvant trial with marimastat is not warranted as chronic administration cannot maintain plasma levels with the target range.

Integrin alpha(v)beta6-associated ERK2 mediates MMP-9 secretion in colon cancer cells

There is general consensus that matrix metalloproteinases are involved in tumour progression. We show herein that inhibition of integrin alpha(v)beta6 expression in colon cancer cells suppresses MMP-9 secretion. This integrin-mediated event is dependent upon direct binding between the beta6 integrin subunit and extracellular signal-regulated kinase 2. Targetting either beta6 or its interaction with extracellular signal-regulated kinase in order to inhibit matrix metalloproteinase activity may offer a useful therapeutic approach in preventing growth and spread of colon cancer.

Marimastat as maintenance therapy for patients with advanced gastric cancer: a randomised trial

This randomised, double-blind, placebo-controlled study was designed to evaluate the ability of the orally administered matrix metalloproteinase inhibitor, marimastat, to prolong survival in patients with non-resectable gastric and gastro-oesophageal adenocarcinoma. Three hundred and sixty-nine patients with histological proof of adenocarcinoma, who had received no more than a single regimen of 5-fluorouracil-based chemotherapy, were randomised to receive either marimastat (10 mg b.d.) or placebo. Patients were treated for as long as was tolerable. The primary endpoint was overall survival with secondary endpoints of time to disease progression and quality of life. At the point of protocol-defined study completion (85% mortality in the placebo arm) there was a modest difference in survival in the intention-to-treat population in favour of marimastat (P=0.07 log-rank test, hazard ratio=1.23 (95% confidence interval 0.98-1.55)). This survival benefit was maintained over a further 2 years of follow-up (P=0.024, hazard ratio=1.27 (1.03-1.57)). The median survival was 138 days for placebo and 160 days for marimastat, with 2-year survival of 3% and 9% respectively. A significant survival benefit was identified at study completion in the pre-defined sub-group of 123 patients who had received prior chemotherapy (P=0.045, hazard ratio=1.53 (1.00-2.34)). This benefit increased with 2 years additional follow-up (P=0.006, hazard ratio=1.68 (1.16-2.44)), with 2-year survival of 5% and 18% respectively. Progression-free survival was also significantly longer for patients receiving marimastat compared to placebo (P=0.009, hazard ratio=1.32 (1.07-1.63)). Marimastat treatment was associated with the development of musculoskeletal pain and inflammation. Events of anaemia, abdominal pain, jaundice and weight loss were more common in the placebo arm. This is one of the first demonstrations of a therapeutic benefit for a matrix metalloproteinase inhibitor in cancer patients. The greatest benefit was observed in patients who had previously received chemotherapy. A further randomised study of marimastat in these patients is warranted.

Matrix metalloproteinases in cancer: prognostic markers and therapeutic targets

Degradation of extracellular matrix is crucial for malignant tumour growth, invasion, metastasis and angiogenesis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent neutral endopeptidases collectively capable of degrading essentially all matrix components. Elevated levels of distinct MMPs can be detected in tumour tissue or serum of patients with advanced cancer and their role as prognostic indicators in cancer is studied. In addition, therapeutic intervention of tumour growth and invasion based on inhibition of MMP activity is under intensive investigation and several MMP inhibitors are in clinical trials in cancer. In this review, we discuss the current view on the feasibility of MMPs as prognostic markers and as targets for therapeutic intervention in cancer.

Matrix metalloproteinase inhibitors and cancer: trials and tribulations

For at least 30 years, matrix metalloproteinases (MMPs) have been heralded as promising targets for cancer therapy on the basis of their massive up-regulation in malignant tissues and their unique ability to degrade all components of the extracellular matrix. Preclinical studies testing the efficacy of MMP suppression in tumor models were so compelling that synthetic metalloproteinase inhibitors (MPIs) were rapidly developed and routed into human clinical trials. The results of these trials have been disappointing. Here we review the studies that brought MPIs into clinical testing and discuss the design and outcome of the trials in light of new information about the cellular source, substrates, and mode of action of MMPs at different stages of tumor progression. The important lessons learned from the MPI experience may be of great value for future studies of MPIs and for cancer drug development in general.

Angiogenesis inhibitors in clinical development for lung cancer

The use of tumor angiogenesis as a therapeutic target is based on extensive literature showing the dependence of tumors on the process of angiogenesis for growth, invasion, and metastasis. Seminal work performed by Folkman three decades ago determined that tumors beyond the size of approximately 2 mm require angiogenesis for subsequent growth and development. This basic hypothesis stimulated research in the field of angiogenesis and has resulted in the identification of factors that both enhance and inhibit this "angiogenic switch." The intent of this article is to present data on several angiogenesis inhibitors that are currently undergoing clinical evaluation in cancer patients. These agents may be particularly useful in the treatment of lung cancer, both as adjunctive therapy in early-stage or locally advanced disease, as well as in combination strategies with platinum-based therapy in metastatic disease. Although angiogenesis inhibitors have been in clinical trials for the past decade, there has been a shift in recent years towards the development of more mechanism-based and receptor-targeted agents. Interestingly, no antiangiogenic agent has been approved as such for use in cancer, perhaps because of the challenges involved in the clinical development of these novel agents. These include the potential requirement for long-term administration, difficulties in deriving biologically efficacious doses in early clinical trials, and the inability to use tumor regression as a primary endpoint in phase II trials.

Matrix metalloproteinases in colorectal cancer

Matrix metalloproteinases (MMPs) appear to play a key role in the development and progression of human malignancies. MMPs mediate the destruction of the extracellular matrix, which is an important early step in tumor invasion and metastasis. Growing evidence suggests that MMPs also have angiogenic activity and participate in the early stages of tumorigenesis and primary tumor growth. Investigations in experimental animal models have confirmed the importance of MMPs in the pathogenesis of colorectal cancer, and studies in humans show a direct association between increased MMP expression and tumor invasiveness, development of metastases, and shortened survival. In this review, the physiologic role of MMPs in normal tissues is examined and data supporting the role of MMPs in the pathogenesis of colorectal cancer are reviewed. The results of clinical trials with MMP inhibitors in colorectal cancer and promising areas for future investigation are also discussed.

Matrix metalloproteinase inhibitors: current developments and future perspectives

Malignant tumors are characterized by invasive growth and metastasis. To facilitate this invasive behavior, the enzymatic breakdown of the extracellular matrix (ECM) is a prerequisite. Many human tumors are characterized by locally increased concentrations of matrix metalloproteinases (MMPs), enzymes that are able to degrade this ECM. A vast number of matrix metalloproteinase inhibitors (MMPIs) have been developed in recent years and after extensive preclinical testing, the results of the first clinical studies with several of these compounds have recently been presented. In this review we will describe some of the basic concepts of the degradation of the ECM, with special emphasis on the role of MMPs in the progression of cancer. Furthermore we will review the results of preclinical and clinical studies with MMPIs and discuss their future perspective.

Antiangiogenesis therapy. Current and future agents

Approaches to cancer therapy for most tumors in adults and children have changed little in 50 years: surgery, radiation, and chemotherapy are standard for many solid tumors. When the concept of angiogenesis in cancer biology was introduced in the 1970s, there was little recognition of the therapeutic potential of attacking a tumor's blood supply. Advances in understanding the molecular processes that regulate tumor blood supply and novel agents that can interfere with them have generated a great deal of scientific interest and excitement. This article reviews the current understanding of angiogenesis and its role in cancer then discusses new therapeutic options in animals and humans, with a focus on pediatric tumors and the potential for treating them.

Antiangiogenic agents and their promising potential in combined therapy

One of the most promising strategies for treating cancer is the addition of antiangiogenic therapy to therapeutic regimens. Angiogenesis, or the growth of new blood vessels from preexisting vessels, is essential both for the growth of a primary tumor and for successful metastasis. As a result of intense research in this field, a number of antiangiogenic agents have been identified and have demonstrated varying degrees of success in inhibiting the growth of solid tumors and metastases in preclinical and clinical studies. The real potential of antiangiogenic agents for cancer therapy resides in strategic combinations with each other, with chemotherapy, with radiation, and with tumor-targeting agents, such as radioimmunotherapy. Along with this new opportunity to develop synergistic therapy comes the challenging complexities of the physiologic systems regulating angiogenesis. These multifaceted systems could intimidate investigators seeking to take advantage of the potential synergy in combined cancer therapy. To aid in these efforts, this overview of key antiangiogenic agent mechanisms, combination strategies and initial studies of the potential synergy with chemotherapy, radiation and radioimmunotherapy is presented.

General aspects of anti-angiogenesis and cancer therapy

Angiogenesis is the outgrowth of new vessels from pre-existing ones. Tumour growth and metastasis is dependent on angiogenesis and many stimulatory and inhibitory factors have been described which play an active role in this process. Inhibition of tumour neovasculature may be one strategy to inhibit tumour growth. Naturally occurring inhibitors of angiogenesis have been discovered and synthetic agents have been designed. Many of these inhibitors are currently being evaluated in clinical trials for the treatment of cancer. This review discusses the mechanism of action of these anti-angiogenics as well as a description of the clinical trials in which they are being evaluated.

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human pancreatic adenocarcinomas: clinicopathologic and prognostic significance of matrilysin expression

PURPOSE

A disruption in the balance between the matrix metalloproteinases (MMPs) and their natural inhibitors, tissue inhibitors of metalloproteinases (TIMPs), has been implicated in the progression of many types of cancer. The aim of this study was to determine whether a specific MMP or TIMP has clinicopathologic and prognostic significance in pancreatic carcinoma.

PATIENTS AND METHODS

Using immunohistochemistry, we analyzed 70 pancreatic ductal adenocarcinoma tissues for expression of MMP-1, MMP-2, MMP-3, MMP-7 (matrilysin), MMP-9, MT1-MMP, TIMP-1, and TIMP-2. The results were matched with clinicopathologic characteristics and patients' survival. The effects of the suppression of a specific MMP on in vitro invasiveness of pancreatic carcinoma cells were also examined.

RESULTS

Expression of MMP-1, MMP-2, MMP-3, matrilysin, MMP-9, MT1-MMP, TIMP-1, and TIMP-2 was detected in either tumor cells or tumor stromal cells, or in both components, at varying frequencies. Among MMPs, matrilysin showed a unique distribution in the tumor nests; its expression was usually most pronounced at the invasive front of the tumors. Sections with immunostaining signals in more than 30% of carcinoma cells at the invasive front, which were observed in 40 cases (57%), were judged to be positive for matrilysin. Matrilysin positivity was significantly correlated with pT, pN, and pM categories and with more advanced pathologic tumor-node-metastasis stages. Patients with matrilysin-positive carcinoma had a significantly shorter overall survival time than did those with matrilysin-negative carcinoma. Matrilysin was a significant independent prognostic factor for overall survival in multivariate analysis. In contrast, there was no correlation between the presence of other MMPs or TIMPs and clinicopathologic characteristics, nor was the presence of individual MMPs or TIMPs related to survival. Antisense matrilysin-transfected CFPAC-1 cells expressed reduced levels of matrilysin and demonstrated a similar growth potential but were less invasive in vitro compared with neotransfected CFPAC-1 cells.

CONCLUSION

Our results suggest that matrilysin may play a key role in progression of pancreatic carcinoma and thereby contribute to a poor prognosis. Because different synthetic MMP inhibitors affect different types of MMPs to a different degree, examination of the expression of MMPs, especially that of matrilysin, may serve as an indicator for selecting the most effective MMP inhibitor.

Development of matrix metalloproteinase inhibitors in cancer therapy

The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases involved in the degradation of the extracellular matrix. The MMPs have been implicated in the processes of tumor growth, invasion, and metastasis; are frequently overexpressed in malignant tumors; and have been associated with an aggressive malignant phenotype and adverse prognosis in patients with cancer. A number of MMP inhibitors are being developed for the treatment of cancer. The most extensively studied class of MMP inhibitors includes collagen peptidomimetics and nonpeptidomimetic inhibitors of the MMP active site, tetracycline derivatives, and bisphosphonates. The hydroxamate peptidomimetic inhibitor batimastat and its orally bioavailable analogue marimastat, which bind covalently to the zinc atom at the MMP-active site, were the first MMP inhibitors to be studied in detail. Marimastat is currently being studied in randomized clinical trials. The nonpeptidic MMP inhibitors were synthesized in an attempt to improve the oral bioavailability and pharmaceutical properties of the peptidic inhibitors. Several members of this class of compounds are undergoing evaluation in phase III clinical trials. The tetracyclines and, particularly, the nonantibiotic chemically modified tetracyclines, interfere with several aspects of MMP expression and activation and inhibit tumor growth and metastases in preclinical models. A representative agent of this class, Col-3, is currently undergoing phase I clinical trials. The development of the MMP inhibitors, like that of other targeted and predominantly antiproliferative compounds, poses a challenge because the paradigms that have governed the design of clinical oncology trials may not be relevant to this new class of agents. The anticipated need for long-term administration of these drugs, together with their cytostatic mechanism of action, will require novel clinical trial design strategies.

Antiangiogenesis -- therapeutic strategies and clinical implications for brain tumors

The poor prognosis of patients with malignant brain tumors in spite of aggressive multimodality therapy has led to the search for novel therapeutic strategies. Among the targets for such treatment approaches, tumor angiogenesis has captured the attention of not only the medical field but also of the lay public because of its conceptual departure from traditional methods of cancer therapy. Angiogenesis and vascular proliferation are particularly important in the growth and progression of malignant gliomas and are used as indicators of the degree of malignancy. Recent studies have helped us gain a better understanding of the molecular mediators of this process. It is now evident that after the initial formation of malignancy the continued growth of a glioma is critically dependent on its angiogenic potential. Hence, several approaches to control angiogenesis are being developed and tested. In the present review, we examine some of these approaches from a therapeutic perspective and summarize the findings from early human trials of such agents.

Ongoing trials with matrix metalloproteinase inhibitors

Excessive or poorly regulated matrix metalloproteinase (MMP) activity has been implicated as a pathogenic factor in a range of diseases where the extracellular matrix is degraded or remodelled. Synthetic, potent, low molecular weight MMP inhibitors (MMPIs) have been developed and, over the past five years, these agents have begun clinical testing in patients with cancer, rheumatoid arthritis, osteoarthritis and acute macular degeneration. The past year has seen a number of disappointments with the halting of clinical trials of Ro 32-3555 in patients with rheumatoid arthritis and of BAY 12-9566 in patients with cancer. There have, however, been some successes with perhaps the clearest indication of efficacy being seen in the results of a Phase III trial of marimastat in patients with advanced gastric cancer. Clinical trials are continuing with marimastat and other MMPIs, including prinomastat, solimastat, BMS 275291, metastat and neovastat. Results from these trials are expected in the next two years and it is likely that clinical trials with MMPIs will begin in patients with other diseases where MMPs are believed to be involved, such as restenosis, cerebral haemorrhage and multiple sclerosis. Future research is likely to focus on the identification of specific MMP targets in different diseases, both in order to improve efficacy and to reduce the musculoskeletal side effect profile that has characterised several of the first generation oral MMPIs.

Synthetic inhibitor of matrix metalloproteases decreases tumor growth and metastases in a syngeneic model of rat prostate cancer in vivo

Members of the matrix metalloprotease (MMP) family are implicated in the progression of several malignancies including prostate cancer due to their ability to break down extracellular matrix (ECM) components. In this study, we have evaluated the ability of a synthetic MMP inhibitor (A-177430) to block tumor growth and metastases in a syngeneic model of rat prostate cancer. In an in vitro substrate assay, A-177430 exhibited nanomolar potency (IC(50) 2-6 nM) against the enzymatic activity of several MMPs. For in vivo studies, male Copenhagen rats were injected s.c. with Mat Ly Lu rat prostate cancer cells (1 x 10(6) cells ) into the right flank and animals were administered i.p.with different doses (10-100 mg/kg per day) of A-177430 for 16 days. Administration of A-177430 resulted in a dose-dependent decrease in tumor volume as compared to a control group of animals receiving vehicle alone. The maximum dose (100 mg/kg per day) of A-177430 exhibited complete arrest in tumor growth and prevented the development of macroscopic tumor metastases to lungs without exhibiting any noticeable side effects. Histologic examination of primary tumors from experimental animals showed extensive tumor necrosis and decreased tumor angiogenesis as determined by factor VIII staining of primary tumors following A-177430 treatment. These primary tumors from experimental animals also exhibited a significant increase in tumor cell DNA fragmentation as determined by TUNEL assay. Collectively, these results demonstrate the ability of MMP inhibitors to block tumor growth and metastases by blocking ECM degradation and by inhibiting tumor angiogenesis and promotion of prostate cancer cell apoptosis in vivo.

Novel anti-cancer agents in development: exciting prospects and new challenges

A large number of cancer chemotherapeutic agents, are in development, many already undergoing clinical testing. A number of these compounds were designed either to modulate or inhibit molecular targets which have been identified as being critical to the development or control of cancer. Targets for inhibition include matrix metalloproteinases, mediators of signal transduction (tyrosine kinases, cyclin dependent kinases and other kinases such as protein kinase C and A) as well as ras expression and prenylation. Classes of potential inhibitory compounds include small molecules, humanized monoclonal antibodies or antisense oligonucleotides. Many of these compounds are relatively well advanced in development. Proof of principle has already been demonstrated in some instances and at least one such compound has been approved for use. Although these new compounds offer exciting opportunities, many bring with them real challenges in terms of the selection of appropriate trial design and surrogate end-points.

Inhibition of tumour growth by marimastat in a human xenograft model of gastric cancer: relationship with levels of circulating CEA

Inhibition of matrix metalloproteinases (MMPs) is an attractive approach to adjuvant therapy in the treatment of cancer. Marimastat is the first orally administered, synthetic MMP inhibitor to be evaluated, in this capacity, in the clinic. Measurement of the rate of change of circulating tumour antigens was used for evaluating biological activity and defining optimum dosage in the early clinical trials of marimastat. Although tumour antigen levels have been used in the clinical management of cancer for many years, they have not been validated as markers of disease progression. In order to investigate the relationship between the effects of marimastat on tumour growth and circulating tumour antigen levels, mice bearing the human gastric tumour, MGLVA1, were treated with marimastat. The MMP inhibitor exerted a significant therapeutic effect, reducing tumour growth rate by 48% (P = 0.0005), and increasing median survival from 19 to 30 days (P = 0.0001). In addition, carcinoembryonic antigen (CEA) levels were measured in serum samples from animals sacrificed at regular intervals, and correlated with excised tumour weight. It was shown that the natural log of the CEA concentration was linearly related to the natural log of the tumour weight and that treatment was not a significant factor in this relationship (P = 0.7). In conclusion, circulating CEA levels were not directly affected by marimastat, but did reflect tumour size. These results support the use of cancer antigens as markers of biological activity in early phase trials of non-cytotoxic anticancer agents.

A pilot study of the safety and effects of the matrix metalloproteinase inhibitor marimastat in gastric cancer

The aim of this study was to evaluate the safety and tolerability of 4 weeks administration of marimastat, and to seek evidence of biological activity as observed by changes in the endoscopic appearance of the gastric tumours. 35 patients with advanced, inoperable gastric or gastro-oesophageal tumours were recruited. The dose of marimastat was reduced from the starting dose of 50 mg twice daily (6 patients) to 25 mg once daily (29 patients). 31 completed the 28 day study period. Marimastat was generally well tolerated, with the principal treatment-related toxicity being pain and stiffness of the musculoskeletal system. These symptoms occurred more frequently at the higher-dose, and increased to involve a total of 13 patients (37%) with longer-term treatment. The events were usually rapidly reversible on drug discontinuation. 3 patients receiving prolonged treatment experienced more severe symptoms, with the development of skin thickening and contractures in the hands. At endoscopy, 10 patients showed an increased fibrotic cover of the tumour, 8 had decreased haemorrhagic appearance, and in at least 2 cases where comparative tumour histology was assessable, there was evidence of increased stromal fibrotic tissue.