Administration of the vasopressin analog desmopressin for the management of bleeding in rectal cancer patients: results of a phase I/II trial.

Purpose The vasopressin analog desmopressin (dDAVP) is known to increase plasma levels of hemostatic factors, and preclinical studies in colorectal cancer models have demonstrated that it hampers tumor vascularization and metastatic progression. We evaluated safety and preliminary efficacy of dDAVP in rectal cancer patients with bleeding, before receiving specific oncologic treatment with surgery, chemotherapy and/or radiotherapy. Methods Patients with rectal cancer having moderate or severe rectal bleeding were enrolled in an open-label, dose-finding trial. Intravenous infusions of dDAVP were administered during two consecutive days in doses from 0.25 to 2.0 µg/kg, using single or twice daily regimen. Bleeding was graded using a score based on the Chutkan scale and tumor perfusion was evaluated by dynamic contrast-enhanced magnetic resonance imaging. Results The trial accrued a total of 32 patients. Dose-limiting toxicity occurred in patients receiving 1 µg/kg or higher. The most prominent treatment-related severe adverse event was hyponatremia. Most patients receiving the maximum tolerated dose of 0.5 µg/kg showed at least a partial hemostatic response and 58% developed a complete response with absence of bleeding at day 4 and/or at the last follow-up at day 14. Tumor perfusion was decreased in two-thirds of patients after dDAVP treatment. Conclusions dDAVP appeared as a promising hemostatic agent in rectal cancer patients with bleeding. Randomized clinical trials to confirm its effectiveness are warranted.Clinical trial registration www.clinicaltrials.gov NCT01623206.

Preclinical Efficacy of [V4 Q5 ]dDAVP, a Second Generation Vasopressin Analog, on Metastatic Spread and Tumor-Associated Angiogenesis in Colorectal Cancer.

PURPOSE: Control of metastatic spread of colorectal cancer (CRC) remains as a major therapeutic challenge. [V4 Q5 ]dDAVP is a vasopressin peptide analog with previously reported anticancer activity against carcinoma tumors. By acting as a selective agonist of arginine vasopressin type 2 membrane receptor (AVPR2) present in endothelial and tumor cells, [V4Q5]dDAVP is able to impair tumor aggressiveness and distant spread. Our aim was to evaluate the potential therapeutic benefits of [V4Q5]dDAVP on highly aggressive CRC disease using experimental models with translational relevance. MATERIALS AND METHODS: Murine CT-26 and human Colo-205 AVPR2-expressing CRC cell lines were used to test the preclinical efficacy of [V4Q5]dDAVP, both in vitro and in vivo. RESULTS: In syngeneic mice surgically implanted with CT-26 cells in the spleen, sustained intravenous treatment with [V4Q5]dDAVP (0.3 µg/kg) dramatically impaired metastatic progression to liver without overt signs of toxicity, and also reduced experimental lung colonization. The compound inhibited in vivo angiogenesis driven by Colo-205 cells in athymic mice, as well as in vitro endothelial cell migration and capillary tube formation. [V4Q5]dDAVP exerted AVPR2-dependent cytostatic activity in vitro (IC50 1.08 µM) and addition to 5-fluorouracil resulted in synergistic antiproliferative effects both in CT-26 and Colo-205 cells. CONCLUSION: The present preclinical study establishes for the first time the efficacy of [V4Q5]dDAVP on CRC. These encouraging. RESULTS: suggest that the novel second generation vasopressin analog could be used for the management of aggressive CRC as an adjuvant agent during surgery or to complement standard chemotherapy, limiting tumor angiogenesis and metastasis and thus protecting the patient from CRC recurrence.

Search of vasopressin analogs with antiproliferative activity on small-cell lung cancer: drug design based on two different approaches.

AIM: Development of compounds with therapeutic application requires the interaction of different disciplines. Several tumors express vasopressin (AVP; arginine vasopressin) receptors with contrasting effects depending on receptor subtype. Desmopressin (dDAVP) is an AVP-selective analog with antiproliferative properties. In this work, an evolutionary approach and a rational strategy were applied in order to design novel AVP analogs. RESULTS: We designed two novel analogs; dDInotocin (dDINT, insect analog), and [V4Q5]dDAVP, and demonstrated the importance of the dDAVP conformational loop for its antiproliferative activity. [V4Q5] dDAVP showed major cytostatic effect on lung cancer cells than dDAVP and its cytostatic effect was abolished by V2R blockade. CONCLUSION: Combination of these strategies could provide the basis for future studies for the development of improved compounds with potential therapeutic applications.

Peptide Agonists of Vasopressin V2 Receptor Reduce Expression of Neuroendocrine Markers and Tumor Growth in Human Lung and Prostate Tumor Cells.

Neuroendocrine tumors (NETs) comprise a heterogeneous group of malignancies that express neuropeptides as synaptophysin, chromogranin A (CgA), and specific neuronal enolase (NSE), among others. Vasopressin (AVP) is a neuropeptide with an endocrine, paracrine, and autocrine effect in normal and pathological tissues. AVP receptors are present in human lung, breast, pancreatic, colorectal, and gastrointestinal tumors. While AVP V1 receptors are associated with stimulation of cellular proliferation, AVP V2 receptor (V2r) is related to antiproliferative effects. Desmopressin (dDAVP) is a synthetic analog of AVP that acts as a selective agonist for the V2r, which shows antitumor properties in breast and colorectal cancer models. Recently, we developed a derivative of dDAVP named [V4Q5]dDAVP, which presents higher antitumor effects in a breast cancer model compared to the parental compound. The goal of present work was to explore the antitumor properties of the V2r agonist dDAVP and its novel analog [V4Q5]dDAVP on aggressive human lung (NCI-H82) and prostate cancer (PC-3) cell lines with neuroendocrine (NE) characteristics. We study the presence of specific NE markers (CgA and NSE) and V2r expression in NCI-H82 and PC-3. Both cell lines express high levels of NE markers NSE and CgA but then incubation with dDAVP diminished expression levels of both markers. DDAVP and [V4Q5]dDAVP significantly reduced proliferation, doubling time, and migration in both tumor cell cultures. [V4Q5]dDAVP analog showed a higher cytostatic effect than dDAVP, on cellular proliferation in the NCI-H82 cell line. Silencing of V2r using small interfering RNA significantly attenuated the inhibitory effects of [V4Q5]dDAVP on NCI-H82 cell proliferation. We, preliminarily, explored the in vivo effect of dDAVP and [V4Q5]dDAVP on NCI-H82 small cell lung cancer xenografts. Treated tumors (0.3 µg kg-1, thrice a week) grew slower in comparison to vehicle-treated animals. In this work, we demonstrated that the specific agonists of V2r, dDAVP, and [V4Q5]dDAVP displays antitumor capacity on different human models of lung and prostate cancers with NE features, showing their potential therapeutic benefits in the treatment of these aggressive tumors.

Addition of vasopressin synthetic analogue [V(4)Q(5)]dDAVP to standard chemotherapy enhances tumour growth inhibition and impairs metastatic spread in aggressive breast tumour models.

[V(4)Q(5)]dDAVP is a novel 2nd generation vasopressin analogue with robust antitumour activity against metastatic breast cancer. We recently reported that, by acting on vasopressin V2r membrane receptor present in tumour cells and microvascular endothelium, [V(4)Q(5)]dDAVP inhibits angiogenesis and metastatic progression of the disease without overt toxicity. Despite chemotherapy remaining as a primary therapeutic option for aggressive breast cancer, its use is limited by low selectivity and associated adverse effects. In this regard, we evaluated potential combinational benefits by adding [V(4)Q(5)]dDAVP to standard-of-care chemotherapy. In vitro, combination of [V(4)Q(5)]dDAVP with sub-IC50 concentrations of paclitaxel or carmustine resulted in a cooperative inhibition of breast cancer cell growth in comparison to single-agent therapy. In vivo antitumour efficacy of [V(4)Q(5)]dDAVP addition to chemotherapy was first evaluated using the triple-negative MDA-MB-231 breast cancer xenograft model. Tumour-bearing mice were treated with i.v. injections of [V(4)Q(5)]dDAVP (0.3 µg/kg, thrice weekly) in combination with weekly cycles of paclitaxel (10 mg/kg i.p.). After 6 weeks of treatment, combination regimen resulted in greater tumour growth inhibition compared to monotherapy. [V(4)Q(5)]dDAVP addition was also associated with reduction of local aggressiveness, and impairment of tumour invasion and infiltration of the skin. Benefits of combined therapy were confirmed in the hormone-independent and metastatic F3II breast cancer model by combining [V(4)Q(5)]dDAVP with carmustine (25 mg/kg i.p.). Interestingly, [V(4)Q(5)]dDAVP plus cytotoxic agents severely impaired colony forming ability of tumour cells and inhibited breast cancer metastasis to lung. The present study shows that [V(4)Q(5)]dDAVP may complement conventional chemotherapy by modulating metastatic progression and early stages of microtumour establishment, and thus supports further preclinical testing of the compound for the management of aggressive breast cancer.

A phase II dose-escalation trial of perioperative desmopressin (1-desamino-8-d-arginine vasopressin) in breast cancer patients.

Desmopressin (dDAVP) is a well-known peptide analog of the antidiuretic hormone vasopressin, used to prevent excessive bleeding during surgical procedures. dDAVP increases hemostatic mediators, such as the von Willebrand factor (vWF), recently considered a key element in resistance to metastasis. Studies in mouse models and veterinary trials in dogs with locally-advanced mammary tumors demonstrated that high doses of perioperative dDAVP inhibited lymph node and early blood-borne metastasis and significantly prolonged survival. We conducted a phase II dose-escalation trial in patients with breast cancer, administering a lyophilized formulation of dDAVP by intravenous infusion in saline, 30-60 min before and 24 h after surgical resection. Primary endpoints were safety and tolerability, as well as selection of the best dose for cancer surgery. Secondary endpoints included surgical bleeding, plasma levels of vWF, and circulating tumor cells (CTCs) as measured by quantitative PCR of cytokeratin-19 transcripts. Only 2 of a total of 20 patients experienced reversible adverse events, including hyponatremia (grade 4) and hypersensitivity reaction (grade 2). Reactions were adequately managed by slowing the infusion rate. A reduced intraoperative bleeding was noted with increasing doses of dDAVP. Treatment was associated with higher vWF plasma levels and a postoperative drop in CTC counts. At the highest dose level evaluated (2 µg/kg) dDAVP appeared safe when administered in two slow infusions of 1 µg/kg, before and after surgery. Clinical trials to establish the effectiveness of adjunctive perioperative dDAVP therapy are warranted. This trial is registered on www.clinicaltrials.gov (NCT01606072).

The novel desmopressin analogue [V4Q5]dDAVP inhibits angiogenesis, tumour growth and metastases in vasopressin type 2 receptor-expressing breast cancer models.

Desmopressin (dDAVP) is a safe haemostatic agent with previously reported antitumour activity. It acts as a selective agonist for the V2 vasopressin membrane receptor (V2r) present on tumour cells and microvasculature. The purpose of this study was to evaluate the novel peptide derivative [V4Q5]dDAVP in V2r-expressing preclinical mouse models of breast cancer. We assessed antitumour effects of [V4Q5]dDAVP using human MCF-7 and MDA-MB-231 breast carcinoma cells, as well as the highly metastatic mouse F3II cell line. Effect on in vitro cancer cell growth was evaluated by cell proliferation and clonogenic assays. Cell cycle distribution was analysed by flow cytometry. In order to study the effect of intravenously administered [V4Q5]dDAVP on tumour growth and angiogenesis, breast cancer xenografts were generated in athymic mice. F3II cells were injected into syngeneic mice to evaluate the effect of [V4Q5]dDAVP on spontaneous and experimental metastatic spread. In vitro cytostatic effects of [V4Q5]dDAVP against breast cancer cells were greater than those of dDAVP, and associated with V2r-activated signal transduction and partial cell cycle arrest. In MDA-MB-231 xenografts, [V4Q5]dDAVP (0.3 µg/kg, thrice a week) reduced tumour growth and angiogenesis. Treatment of F3II mammary tumour-bearing immunocompetent mice resulted in complete inhibition of metastatic progression. [V4Q5]dDAVP also displayed greater antimetastatic efficacy than dDAVP on experimental lung colonisation by F3II cells. The novel analogue was well tolerated in preliminary acute toxicology studies, at doses ≥ 300-fold above that required for anti-angiogenic/antimetastatic effects. Our data establish the preclinical activity of [V4Q5]dDAVP in aggressive breast cancer, providing the rationale for further clinical trials.

Insight into the effect of the vasopressin analog desmopressin on lung colonization by mammary carcinoma cells in BALB/c mice.

BACKGROUND/AIM: Desmopressin (dDAVP) is a synthetic peptide analog of vasopressin with antidiuretic and hemostatic properties. Recent experimental evidence have suggested that dDAVP can inhibit metastasis formation by agonist action on V2 vasopressin receptors present in both tumor and endothelial cells. We have examined the kinetics of dDAVP effect during metastatic colonization and its potential association with hemostasis. MATERIALS AND METHODS: The experimental metastasis assay was performed by injecting F3II mammary carcinoma cells into the lateral tail vein of syngeneic female BALB/c mice. RESULTS: Clinically relevant doses of dDAVP (0.3 to 2 µg/kg intravenously (i.v.)) produced a dose-dependent inhibition in the formation of lung nodules when administered during the first 24 hours after F3II tumor cell injection. The hemostatic agent tranexamic acid (10 mg/kg, i.v.) had no effect on metastasis formation in the same experimental conditions, while the anticoagulant enoxaparin (1 mg/kg, subcutaneously (s.c.)) did not modify the antimetastatic action of dDAVP. In vitro, dDAVP had a strong inhibitory effect on F3II cell colony formation. CONCLUSION: dDAVP interferes with early metastatic disease, and direct association of this effect with hemostatic mechanisms is unlikely.

Structure-activity relationship of 1-desamino-8-D-arginine vasopressin as an antiproliferative agent on human vasopressin V2 receptor-expressing cancer cells.

The synthetic nonapeptide 1­desamino­8­D­arginine vasopressin (dDAVP) can reduce tumor cell growth through agonist action on the vasopressin V2 receptor. A structure­antiproliferative activity relationship analysis of dDAVP was performed using the alanine scanning technique on the aggressive MDA­MB­231 human breast carcinoma cell line. The results from this analysis demonstrated that the amino acids located at the loop of dDAVP are important for the antiproliferative activity of dDAVP, highlighting the key role of the N­terminal region of the peptide in the interaction with the tumor cell surface receptor. The findings from this study present novel strategies for designing improved compounds with enhanced stability for cancer therapy.

The functional interaction between Acyl-CoA synthetase 4, 5-lipooxygenase and cyclooxygenase-2 controls tumor growth: a novel therapeutic target.

The acyl-CoA synthetase 4 (ACSL4), which esterify mainly arachidonic acid (AA) into acyl-CoA, is increased in breast, colon and hepatocellular carcinoma. The transfection of MCF-7 cells with ACSL4 cDNA transforms the cells into a highly aggressive phenotype and controls both lipooxygenase-5 (LOX-5) and cyclooxygenase-2 (COX-2) metabolism of AA, suggesting a causal role of ACSL4 in tumorigenesis. We hypothesized that ACSL4, LOX-5 and COX-2 may constitute potential therapeutic targets for the control of tumor growth. Therefore, the aim of this study was to use a tetracycline Tet-Off system of MCF-7 xenograft model of breast cancer to confirm the effect of ACSL4 overexpression on tumor growth in vivo. We also aim to determine whether a combinatorial inhibition of the ACSL4-LOX-COX-2 pathway affects tumor growth in vivo using a xenograft model based on MDA-MB-231 cells, a highly aggressive breast cancer cell line naturally overexpressing ACSL4. The first novel finding is that stable transfection of MCF-7 cells with ACSL4 using the tetracycline Tet-Off system of MCF-7 cells resulted in development of growing tumors when injected into nude mice. Tumor xenograft development measured in animals that received doxycycline resulted in tumor growth inhibition. The tumors presented marked nuclear polymorphism, high mitotic index and low expression of estrogen and progesterone receptor. These results demonstrate the transformational capacity of ACSL4 overexpression. We examined the effect of a combination of inhibitors of ACSL4, LOX-5 and COX-2 on MDA-MB-231 tumor xenografts. This treatment markedly reduced tumor growth in doses of these inhibitors that were otherwise ineffective when used alone, indicating a synergistic effect of the compounds. Our results suggest that these enzymes interact functionally and form an integrated system that operates in a concerted manner to regulate tumor growth and consequently may be potential therapeutic targets for the control of proliferation as well as metastatic potential of cancer cells.

Effects of the synthetic vasopressin analog desmopressin in a mouse model of colon cancer.

Experimental and clinical data indicated that perioperative administration of the hemostatic peptide desmopressin (DDAVP) can inhibit progression of residual metastatic cells. The compound seems to act by inducing an agonist effect on specific V2 vasopressin membrane receptors present in both tumor cells and endothelial cells. Here we explored the antitumor effects of DDAVP in cultured colon carcinoma cells and in a syngeneic Balb/c mouse model. Both human Colo-205 and mouse CT-26 colon carcinoma cell lines expressed the V2 receptor, as revealed by immunofluorescence. DDAVP (at doses ranging from 100 ng/ml to 1 µg/ml) exerted a modest but significant antiproliferative effect on cultured CT-26 and Colo-205 cells. In vivo, DDAVP (2 intravenous doses of 2 µg/kg) reduced accumulation of ascites and formation of intestinal tumor nodules in mice intraperitoneally inoculated with CT-26 cells. Perioperative administration of DDAVP significantly inhibited tumor progression in animals surgically implanted in the spleen with CT-26 cells, and caused some reduction in liver metastasis. Although DDAVP and 5-fluorouracil demonstrated additive cytostatic effects in vitro, no antitumor effects were observed in this study in mice receiving a single cycle of chemotherapy (25 mg/kg) in combination with the peptide. Our data suggest that DDAVP may be potentially used to minimize spread or survival of residual malignant cells during surgical procedures for colon and other gastrointestinal tumors.

Antitumor effects of desmopressin in combination with chemotherapeutic agents in a mouse model of breast cancer.

The vasopressin peptide analog desmopressin has been used during surgery to prevent bleeding in patients with coagulation defects. Recent experimental and clinical data revealed that perioperative desmopressin therapy can minimize the spread and survival of residual cancer cells. Here, we explored the antitumor effects of desmopressin in combination with chemotherapeutic agents using the F3II mammary carcinoma in syngeneic Balb/c mice. Intravenous administration of desmopressin at a dose of 2 microg/kg together with weekly cycles of carmustine (20 mg/kg) prevented primary tumor infiltration of the skin. Combination of desmopressin with paclitaxel (25 mg/kg) significantly reduced metastatic progression to the lung. Although desmopressin had an antiproliferative effect on F3II cells, in vitro studies did not demonstrate an enhanced cytotoxicity with chemotherapy. Our results suggest that desmopressin may contribute to impair aggressiveness of residual mammary tumors during chemotherapy.

Perioperative desmopressin prolongs survival in surgically treated bitches with mammary gland tumours: a pilot study.

Desmopressin (1-deamino-8-d-arginine vasopressin, also known as DDAVP) is a safe haemostatic compound capable of inhibiting lymph node and lung metastasis in a mouse model of mammary tumour manipulation and surgical excision. The aim of this study was to test the efficacy and safety of perioperative DDAVP (1microg/kg) in surgically treated bitches with mammary gland tumours (MGT). Twenty-one, otherwise healthy, intact bitches, with malignant MGT stage III or IV were randomly allocated to DDAVP (n=11) or placebo (n=10) groups. En bloc mastectomy of the affected gland/s was performed. DDAVP had a significant beneficial effect on disease-free period (P<0.01) and overall survival time (P<0.05). No side effects were seen in any of the cases. Whatever the mechanism of action, it seems that DDAVP may have a novel use in cancer surgery to minimise spread or survival of residual malignant cells. Additional, large scale controlled trials are required to fully evaluate this adjuvant pharmacological protocol.

Complete antitumor protection by perioperative immunization with GM3/VSSP vaccine in a preclinical mouse melanoma model.

PURPOSE: The GM3/VSSP vaccine is composed of very small sized proteoliposomes resulting from the hydrophobic conjugation of GM3 ganglioside with membrane proteins from Neisseria meningitidis. Previously, we showed that preventive vaccination with GM3/VSSP induces a specific antitumor response and elicits the rejection of syngeneic GM3-positive melanoma cells in immunized mice. Our aim was to explore the antitumor properties of perioperative GM3/VSSP vaccination in a preclinical mouse model. EXPERIMENTAL DESIGN: The highly metastatic B16F10 mouse melanoma was used to investigate perioperative vaccination with GM3/VSSP. The vaccine was administered i.m. in doses of 120 microg emulsified with the adjuvant Montanide ISA 51 at weekly or biweekly intervals, and s.c. tumors were excised 25 to 31 days after tumor cell implantation. The persistence of antitumor protection and dose dependency was also examined in preimmunized animals. To evaluate the immune performance of tumor-bearing and tumor-operated mice, ovoalbumin-specific delayed-type hypersensitivity, cytokine secretion, and cell proliferation responses were studied. RESULTS: Surgical excision of B16F10 tumors improved survival, and perioperative immunization with four biweekly GM3/VSSP doses yielded survival for all animals (P = 0.04; log-rank test). Mice showed neither local recurrence nor lung metastasis at the end of the experiment. An impairment of CD4(+) T-cell responses was observed in tumor-bearing animals measured as neoantigen-specific delayed-type hypersensitivity, with a significant recovery after surgery. A strong interleukin-4 secretion was induced in B16F10-operated mice, whereas IFN-gamma remained unaffected. CONCLUSION: Preclinical evidence suggests that GM3/VSSP vaccine might have therapeutic potential to induce antitumor immunity in patients with minimal residual disease after surgery, thereby preventing or prolonging the time to recurrence.

Desmopressin and other synthetic vasopressin analogues in cancer treatment.

Desmopressin (DDAVP) is a well tolerated and convenient haemostatic agent that can be used in a number of clinical conditions with bleeding diathesis. It has several effects on the haemostatic system, causing endogenous release of coagulation factor VIII, von Willebrand factor and tissue-type plasminogen activator, among others. In this review we present a growing body of evidence showing that DDAVP treatment may impair spread of cancer cells and contribute to encapsulation of tumour tissue. Our data in preclinical animal models suggest a potential application of DDAVP in the perioperative management of aggressive solid tumours. Novel vasopressin analogues with improved antitumor effects are currently in development.

Desmopressin reduces melanoma lung metastasis in transgenic mice overexpressing tissue inhibitor of metalloproteinases-1.

Desmopressin (DDAVP) is a synthetic vasopressin analog capable of inducing an increase in the plasma levels of von Willebrand factor and coagulation factor VIII. DDAVP has been used during surgery to prevent bleeding in patients with coagulation defects. We have previously demonstrated that adjuvant perioperative DDAVP therapy inhibits lung and lymph node metastasis in a breast cancer model. Here the effect of DDAVP on experimental lung colonization of B16 melanoma cells was investigated in a transgenic mice model with high levels of tissue inhibitor of metalloproteinases-1 (TIMP-1) in the systemic circulation. Transgenic C57BL/6j-CBA mice overexpressing human TIMP-1 in the liver under the control of the mouse albumin promoter/enhancer were employed. Treatment with DDAVP (2 microg/kg/dose) at the time of intravenous injection of B16 cells significantly inhibited the formation of lung metastases in TIMP-1 transgenic animals (p = 0.021), while no significant effect was obtained in control hybrid mice. The inhibition was not due to direct cytotoxic effects of DDAVP on tumor cells and no expression of vasopressin receptors was detected in B16 cells. Our data indicate that DDAVP therapy may impair successful implantation of circulating melanoma cells and suggest that high levels of circulating TIMP-1 display a cooperative role in the antitumor activity of the compound.

Altered tumor angiogenesis and metastasis of B16 melanoma in transgenic mice overexpressing tissue inhibitor of metalloproteinases-1.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) has emerged as a multifunctional protein that plays contrasting roles during angiogenesis and cancer spread. We have investigated the growth, vascularization and metastasis of B16 melanoma cells in a transgenic mouse model with elevated TIMP-1 levels in the systemic circulation. Transgenic C57BL/6j-CBA mice overexpressing human TIMP-1 in the liver under the control of the mouse albumin promoter/enhancer were employed. An early subcutaneous growth advantage and an increased tumor angiogenic response were observed in transgenic animals with respect to wild-type hybrid mice. On the contrary, there was a dramatic decrease in the lung colonizing ability of B16 melanoma cells in TIMP-1 transgenic mice. No significant effect on metastasis formation was observed in another transgenic mouse model with increased TIMP-1 expression in lungs but low plasma levels, where the transgene was placed under the control of the murine mammary tumor virus promoter. These results support the notion that TIMP-1 displays paradoxical effects on tumor progression and suggest that circulating TIMP-1 is efficient in suppressing lung colonization of melanoma cells.

Role of cell surface GM3 ganglioside and sialic acid in the antitumor activity of a GM3-based vaccine in the murine B16 melanoma model.

PURPOSE: To examine the role of GM3 monosialoganglioside and sialic acid in the antitumor activity of a vaccine based on GM3, hydrophobically conjugated with the outer-membrane-protein complex from Neisseria meningitidis (GM3/VSSP). METHODS: In order to evaluate the relationship between antitumor activity and the presence of GM3 on the surface of tumor cells, we used two murine tumor cell lines with different ganglioside expression. Syngeneic mice were immunized with four i.m. doses of GM3/VSSP (120 micro g) at 14-day intervals and challenged subcutaneously with tumor cells. RESULTS: B16 melanoma cells showed GM3 on cell surface and GM3-dependent in vitro growth. As expected, preimmunization with the vaccine significantly inhibited tumor formation and prolonged survival in mice challenged with B16 cells. In contrast, no antitumor effect was observed in mice challenged with GM3-negative F3II mammary carcinoma cells. The reactivity of sera from immunized mice against B16 cells was confirmed by flow cytometry and immunoperoxidase staining. Depletion of sialic acid residues from the cell surface completely abolished antibody response against melanoma cells. CONCLUSIONS: These results indicate that the antitumor activity of GM3/VSSP is associated with GM3 expression on tumor cell surface and demonstrate a major role of sialic acid in the humoral response of vaccinated mice.

Desmopressin inhibits lung and lymph node metastasis in a mouse mammary carcinoma model of surgical manipulation.

BACKGROUND AND OBJECTIVES: Desmopressin (DDAVP) is a synthetic derivative of vasopressin with hemostatic and fibrinolytic properties that has been used during surgery in patients with bleeding disorders. Our aim was to investigate the effect of DDAVP on lung and lymph node metastatic cell colonization using a preclinical mouse mammary carcinoma model of subcutaneous tumor manipulation and surgical excision. METHODS: Female BALB/c mice bearing the highly aggressive F3II mammary carcinoma were subjected to repeated manipulations of primary tumors (0.5 kg/cm(2) during 2 min), followed (or not) by surgical excision. DDAVP was administered intravenously 30 min before and 24 h after each manipulation or surgery, at a dose of 2 microg/kg. At the end of the experiment, mice were sacrificed and necropsied. RESULTS: Tumor manipulation induced dissemination to the axillary nodes and increased up to 6-fold the number of metastatic lung nodules. Perioperative treatment with DDAVP dramatically reduced regional metastasis. The incidence of lymph node involvement in manipulated animals was 12% with DDAVP and 87% without treatment (P < 0.02). Histopathological analysis of axillary nodes from DDAVP-treated animals showed sinusal histiocytosis and no evidence of cancer cells. Metastatic lung nodules were also reduced about 65% in animals treated with DDAVP (P = 0.026). CONCLUSIONS: Our results suggest a potential clinical application of DDAVP in the management of breast cancer, as well as other aggressive solid tumors. DDAVP may be useful to reduce the risk of metastatic cell colonization both during and after surgical manipulation.