Neoadjuvant chemotherapy for gastric cancer with peritoneal dissemination

An early detection and treatment of gastric cancer with peritoneal dissemination are rather difficult so that a clinical trial has been neglected. Therefore, we introduced a pre-operative peritoneal lavage diagnosis for gastric cancer patients with serosa-invaded tumors. Neoadjuvant chemotherapy was introduced to patients with positive cytology and with no non-curative factors except peritoneum. The neoadjuvant chemotherapy followed by surgery was done safely. The patients with the disappearance of CY and P factors due to neoadjuvant chemotherapy had a better prognosis than those with positive results of CY or R However, many of the patients with negative results from peritoneum eventually suffered a peritoneal recurrence. We started another protocol study with S-1 and an intra-peritoneal chemotherapy using docetaxel. The efficacy in the protocol result will be expected.     

Treatment strategy for primary gastric cancer with peritoneal dissemination

Curative resection is considered to be a standard therapy for gastric cancer with localized peritoneal metastases. For tumors with diffuse dissemination, chemotherapy may play a major role, however, the benefits of reduction surgery and standard chemotherapy have not yet been clarified. Median survival time after reduction surgery was reported to be 4-13 months for patients diagnosed by surgery and/or CT and 5-6 months for chemotherapy for those diagnosed by CT alone. Reduction surgery has a high risk, with a morbidity of 12-44% and a mortality of 3-14%. Palliative surgery should be indicated for stenosis or bleeding due to primary tumors. 5-FU, MTX-5-FU, TS-1, paclitaxel, and their combination are candidates for practice and clinical trials. It is important to evaluate the severity of peritoneal dissemination by diagnostic laparoscopy or laparotomy for decision making.     

Cytoreductive surgery and sandwich therapy with chemohyperthermic peritoneal perfusion and intra-aortic chemotherapy for peritoneal dissemination in gastric cancer

Cytoreductive resection (RST), chemohyperthermic peritoneal perfusion (CHPP) and/or intra-aortic chemotherapy (IA-chemo) were performed for peritoneal dissemination in gastric cancer. Ninety-six patients with peritoneal dissemination were grouped into tubercular (TB), 40; nodular (ND), 31; diffuse (DF) type, 19; and others, 6, respectively, by the gross findings. Sixty-three patients underwent RST. Fifty-nine patients received CHPP by 10-liter heated saline. Thirty patients underwent intra-aortic catheterization for the IA-chemo. The 1-year and 2-year survival rate (1-ysr and 2-ysr) of the RST(+) group were 47% and 10% significantly greater than the 9% and 0% of the RST(-) group (p<0.001). The 1-ysr and 2-ysr of the CHPP(+) group were 37% and 11% significantly greater than the 27% and 0% of the CHPP(-) group (p=0.04). In the TB type the 1-ysr and 2-ysr of the former was 43% and 8% significantly greater than the 15% and 0% of the latter (p=0.04). But there was no significant difference in survival time between the CHPP(+) and the CHPP(-) group in the ND type (p=0.22) or in the DF type (p=0.42). The 1-ysr and 2-ysr of the IA-chemo(+) group were 49% and 19% significantly greater than the 27% and 2% of the IA-chemo(-) group (p<0.01). In the DF type the 1-ysr and 2-ysr of the former was 50% and 33% significantly greater than the 8% and 0% of the latter (p=0.02). However, there was no significant difference in survival time between the IA-chemo(+) and the IA-chemo(-) group in the TB type (p=0.06) or in the ND type (p=0.50). Moreover, the effect of the combination therapy of CHPP and IA-chemo (the sandwich therapy, SDW) were examined. The 1-ysr and 2-ysr of the SDW(+) group were 49% and 22% significantly greater than the 24% and 0% of the SDW(-) group (p=0.002). The sandwich therapy should be performed in addition to cytoreductive surgery for improvement of prognosis in the patient with intractable peritoneal dissemination.     

Intraperitoneal chemotherapy in gastric cancer patients with peritoneal dissemination

Peritoneal dissemination is one of the non-curative factors in gastric cancer and colon cancer. Although many treatments have been conducted for peritoneal dissemination, no standard chemotherapy has yet been established. For sometime we had used continuous hyperthermic peritoneal perfusion (CHPP)for peritoneal dissemination in gastric cancer and colon cancer. CHPP has a marked survival benefit for scirrhous type gastric cancer patients without liver metastasis. Patients with prophylactic CHPP have significantly better prognoses than those without prophylactic CHPP, and therapeutic CHPP has a survival benefit for gastric cancer patients with slight to moderate peritoneal dissemination (P 1-2). But CHPP has no significant prognostic benefit for gastric cancer patients with severe peritoneal dissemination (P 3). Therefore, a new cancer treatment is needed for those patients. On the other hand, many kinds of anticancer agents, including cisplatin, via intraperitoneal (ip) administration have been tried thus far for peritoneal dissemination therapy. Especially, intraperitoneal taxane anticancer agent is very effective for the treatment and local control of severe peritoneal dissemination in gastric cancer. A phase I/II study of taxane anticancer agents via ip administration should be tried in gastric cancer patients with peritoneal dissemination.     

Prediction and treatment of peritoneal dissemination in gastric cancer

In advanced gastric cancer, the frequency of relapses such as metastasis to the peritoneum is high. For this reason, prognostic and treatment methods were studied. In 457 cases in which diagnostic cytology was utilized, 36 (61%) of the 59 cases in which dissemination had been macroscopically observed (P 1) were positive. Moreover, 13 cases of P 0 were also positive. The prognosis of the positive cases was worse, but there was not a significant statistical difference between the positive and negative cases. Chemotherapy has become the most common treatment because of the appearance of new anticancer drugs. TS-1 and paclitaxel were repeatedly administered in 10 cases, and the median survival time was 17 months. These drugs were effective even in carcinoma of the peritoneum, and an improvement in the prognosis can be expected. Surgery was performed in 23 cases due to stenosis of the digestive tract, and in 21 cases the patients were able to eat after surgery. The median postoperative survival time was 7 months, and surgery improved the prognosis. The improved sensitivity of diagnostic cytology and the standardization of chemotherapy and surgery warrant further study.     

Photodynamic therapy using nanoparticle loaded with indocyanine green for experimental peritoneal dissemination of gastric cancer

Although there have been multiple advances in the development of novel anticancer agents and operative procedures, prognosis of patients with advanced gastric cancer remains poor, especially in patients with peritoneal metastasis. In this study, we established nanoparticles loaded with indocyanine green (ICG) derivatives: ICG loaded lactosomes (ICGm) and investigated the diagnostic and therapeutic value of photodynamic therapy (PDT) using ICGm for experimental peritoneal dissemination of gastric cancer. Experimental peritoneal disseminated xenografts of human gastric cancer were established in nude mice. Three weeks after intraperitoneal injection of the cancer cells, either ICGm (ICGm‐treated mice) or ICG solution (ICG‐treated mice) was injected through the tail vein. Forty‐eight hours after injection of the photosensitizer, in vivo and ex vivo imaging was carried out. For PDT, 48 h after injection of the photosensitizer, other mice were irradiated through the abdominal wall, and the body weight and survival rate were monitored. In vivo imaging revealed that peritoneal tumors were visualized through the abdominal wall in ICGm‐treated mice, whereas only non‐specific fluorescence was observed in ICG‐treated mice. The PDT reduced the total weight of the disseminated nodules and significantly improved weight loss and survival rate in ICGm‐treated mice. In conclusion, ICGm can be used as a novel diagnostic and therapeutic nanodevice in peritoneal dissemination of gastric cancer.     

Effectiveness of continuous hyperthermic peritoneal perfusion for the peritoneal dissemination of gastric cancer

We investigated the effectiveness of continuous hyperthermic peritoneal perfusion (CHPP) for the peritoneal dissemination of gastric cancer. A total 124 patients with advanced gastric cancer were enrolled in this study. Prophylactic CHPP (P-CHPP) was performed in 45 patients who had macroscopic serosal invasion without peritoneal dissemination, and 79 patients without CHPP were a control group. Therapeutic CHPP (T-CHPP) was performed in 21 patients with peritoneal dissemination, and 52 patients without CHPP were a control group. There was no significant difference in 5 year survival between patients treated and not treated with P-CHPP. Univariate analysis showed that location of tumor, tumor diameter, and lymph node metastasis influenced prognosis, but there was no prognostic factor in the Cox proportional regression hazard model. There was no significant difference in 5-year survival between patients treated and not treated with T-CHPP. Univariate analysis showed that degree of peritoneal dissemination and adjuvant chemotherapy influenced prognosis, and the Cox proportional regression hazard model showed that the macroscopic types and degree of peritoneal dissemination affected prognosis. In the patients with CHPP, the incidences of respiratory failure and renal failure were each statistically greater than in the patients undergoing CHPP.     

Intracellular targeting therapy of cisplatin-encapsulated transferrin-polyethylene glycol liposome on peritoneal dissemination of gastric cancer

Peritoneal dissemination in gastric cancer is a common fatal clinical condition with few effective therapies available. We studied the therapeutic effect of a tumor-targeting drug delivery system that uses cisplatin-encapsulated and Tf-conjugated PEG liposomes (Tf-PEG liposomes) in nude mice with peritoneal dissemination of human gastric cancer cells. Small unilamellar Tf-PEG, PEG or DSPC/CH liposomes (bare liposomes) encapsulating cisplatin were prepared by reverse-phase evaporation followed by extrusion. Electron microscopic studies revealed that Tf-PEG liposomes were internalized into tumor cells by receptor-mediated endocytosis. To examine the biodistribution of each liposome and cisplatin level, nude mice were inoculated i.p. with 10(7) MKN45P human gastric tumor cells. On the fourth day after tumor inoculation, (3)H-CHE-labeled and cisplatin-encapsulated Tf-PEG, PEG or bare liposome were inoculated i.p. The Tf-PEG liposome-administered group maintained high liposome and cisplatin levels in ascites and showed a prolonged residence time in the peripheral circulation. Uptake of Tf-PEG liposomes into the liver and spleen was significantly lower than that of bare liposomes. Uptake of Tf-PEG liposomes in disseminated tumor cells of ascites and the greater omentum was significantly higher than that of PEG or bare liposomes and a significant increase in cisplatin levels was observed in these tumor cells. Mice receiving Tf-PEG liposomes 1 and 4 days after the day of tumor inoculation showed significantly higher survival rates compared with those receiving PEG liposomes without Tf, bare liposomes or free cisplatin solution. These results suggest that cisplatin-encapsulated Tf-PEG liposomes may be useful as a new intracellular targeting carrier for treatment of gastric cancer with peritoneal dissemination.     

Phosphoglycerate kinase 1 a promoting enzyme for peritoneal dissemination in gastric cancer

Peritoneal carcinomatosis is a frequent finding in gastric cancer associated with a poor prognosis. The features that enable gastric tumors to disseminate are poorly understood until now. Previously, we showed elevated mRNA levels of phosphoglycerate kinase 1 (PGK1), an adenosine triphosphate‐generating enzyme in the glycolytic pathway, the chemokine receptor 4 (CXCR4), the corresponding chemokine ligand 12 (CXCL12) and β‐catenin in specimens from gastric cancer patients with peritoneal carcinomatosis. In this study, the influence of PGK1 on CXCR4 and β‐catenin was assessed as well as the invasiveness of PGK1 overexpressing cancer cells. In this current study, we found that PGK1 regulates the expression of CXCR4 and β‐catenin at the mRNA and protein levels. On the other hand, CXCR4 regulates the expression of PGK1. Plasmid‐mediated overexpression of PGK1 dramatically increased the invasiveness of gastric cancer cells. Interestingly, inhibition of CXCR4 in cells overexpressing PGK1 produced only a moderate reduction of invasiveness suggesting that, PGK1 itself has a critical role in tumor invasiveness. Immunohistochemistry in specimens from diffuse gastric cancer patients also revealed an overexpression of PGK1 in patients with development of peritoneal carcinomatosis. Therefore, PGK1 may be a crucial enzyme in peritoneal dissemination. Together these findings suggest that the enhanced expression of PGK1 and its signaling targets CXCR4 and β‐catenin in gastric cancer cells promote peritoneal carcinomatosis. Thus, PGK1 may serve as prognostic marker and/or be a potential therapeutic target to prevent dissemination of gastric carcinoma cells into the peritoneum.     

Continuous hyperthermic peritoneal perfusion with cisplatin and mitomycin C for peritoneal dissemination in gastric cancer

Thirty-four patients with advanced gastric cancers had received continuous hyperthermic peritoneal perfusion (CHPP) for prevention or treatment of peritoneal dissemination (PD). These patients received intra-abdominal perfusion 30-40 minutes by about 10-liter saline heated to 50-52 degrees C dissolving 200-300 mg cisplatin (CDDP) and 20-30 mg mitomycin C (MMC). The perfusate was infused in the peritoneal cavity through the peritoneal cavity expander (PCE Nihon Kayaku Co. Ltd.) newly developed for sufficient irrigation in our clinic. Eleven patients with macroscopic serosal invasion without PD (P0) or with mild PD (P1) underwent prophylactic CHPP for prevention of peritoneal recurrence. (Pn means degree of PD according to The General Rules for the Gastric Cancer Study.) Twenty-three patients with moderate PD (P2) or severe PD (P3) underwent therapeutic CHPP. The prognosis of patients having undergone prophylactic or therapeutic CHPP (CHPP (+) group) was compared with those not having done CHPP (CHPP (-) group) in the historical control study. In the prophylactic study two-year-survival rates of CHPP (+) group was 90% significantly higher than 63% in CHPP (-) group. There was no significant difference between two-year-survival rates of CHPP (+) (11%) and CHPP (-) (0%) in the therapeutic CHPP. But ascites was observed to disappear in five of twelve (41.7%). Surprisingly second look operation disclosed macroscopic and microscopic disappearance of PD in three of nine (33.3%). The side-effects in those patients had consisted of leakage, bone marrow suppression, perforation of small bowel and so on. But there was no mortality after introduction of PCE. About laboratory data, rises in WBC, BUN, creatinine and LDH and drops in total lymphocytes counts and platelets were all normalized within four weeks. The maximal concentrations of total and free, which emerged at five minutes after CHPP, were 2.19 and 1.29 micrograms/ml. These results suggested that CHPP with CDDP and MMC was well tolerated and effective for prevention of peritoneal recurrence and treatment of peritoneal dissemination in the gastric cancer.     

Retrospective analysis of treatment for advanced gastric cancer with peritoneal dissemination

Recent development and clinical application of novel anticancer agents like S-1 have been reported to show a good outcome against gastric cancer (GC) with peritoneal dissemination (P). In our study, a retrospective analysis of the treatment for GC with P was performed. Since 1989, a chemosensitivity test with MTT assay (MTTA) using surgical specimen was performed to choose chemotherapy after surgery, resulting in good prognosis in patients who received drugs which were determined effective by the MTTA. Since 1999, S-1 was introduced as adjuvant chemotherapy, and, since 2002, initial treatment with S-1/CDDP was used for GC with P, suggesting a better prognostic outcome compared with previous results with ineffective chemotherapy or surgery alone. In conclusion, prognosis of GC with P has been improving by effective regimens with novel anticancer agents like S-1. Further research and clinical trials will be necessary to achieve a more satisfactory outcome with the treatment of GC with P.     

Neoadjuvant treatment of gastric cancer with peritoneal dissemination.

AIMS: To report our experience of neoadjuvant intraperitoneal and systemic chemotherapy (NIPS) for patients having a complete resection of the primary gastric cancer and peritoneal carcinomatosis (PC). PATIENTS AND METHODS: Patients with advanced peritoneal dissemination of primary gastric cancer had the placement of a peritoneal port system. For intraperitoneal chemotherapy, 40 mg of docetaxel and 150 mg of carboplatin were introduced in 1000 ml of saline on a weekly basis. Simultaneously, 100 mg/m2 of methotrexate and 600 mg/m2 of 5-fluorouracil were infused via a peripheral vein. A minimum of two cycles and up to six cycles of NIPS were used prior to cancer resection. At surgery a complete removal of the primary gastric cancer and the peritoneal implants by peritonectomy was attempted. RESULTS: Sixty-one patients were enrolled in the study. Thirty-nine had positive intraperitoneal cytology which reverted to negative cytology after treatment in 22. Thirty-eight showed a partial response. Thirty patients came to resection and 14 patients could be made disease-free. Median survival time of all patients was 14.4 months. Patients who received a complete resection had a median survival time of 20.4 months. Grade III/IV toxicities were not found after two courses of NIPS, but did develop in seven patients after more than three courses of NIPS. CONCLUSION: NIPS can downstage large volume peritoneal dissemination of gastric cancer. When combined with gastrectomy including peritonectomy a complete surgical resection was possible in one-quarter of the patients and resulted in a prolonged survival. This combined intraperitoneal and systemic chemotherapy for PC from gastric cancer is worthy of consideration for phase III clinical investigations.     

ICAM-2 gene therapy for peritoneal dissemination of scirrhous gastric carcinoma.

PURPOSE: Human scirrhous gastric carcinoma develops peritoneal dissemination with high frequency, and the prognosis of patients with peritoneal metastasis is poor. There have been few reports of an immunogene therapy for peritoneal dissemination. Intercellular adhesion molecule (ICAM)-2 is a second ligand of leukocyte function-associated antigen-1, which functions as a costimulatory molecule for effector cells. In the present study, we examined whether ICAM-2 transfection using adenovirus vector is effective gene therapy for peritoneal metastasis of gastric cancer. EXPERIMENTAL DESIGN: We constructed an adenovirus vector, AdICAM-2, that encodes the full-length human ICAM-2 gene under control of the cytomegalovirus promoter. This vector expresses high levels of ICAM-2 on the human gastric cancer cell line OCUM-2MD3, which has high peritoneal metastatic ability in nude mice. We investigated the antitumor effects of gene transfer of ICAM-2 using the adenovirus vector AdICAM-2 in vitro and in vivo. RESULTS: ICAM-2 expressed on OCUM-2MD3 cells by AdICAM-2 demonstrated significantly high adhesiveness to and cytotoxicity against peripheral blood mononuclear cells in vitro compared with the control adenovirus vector AdlacZ. Intratumoral injection of AdICAM-2 significantly inhibited the growth of s.c. tumor. Mice with peritoneal metastasis survived for a significantly longer time after AdICAM-2 injection, compared with injection of AdlacZ. Histopathological findings revealed that many natural killer cells infiltrated the peritoneal metastatic lesions after AdICAM-2 injection. CONCLUSIONS: These findings suggest that transduction of ICAM-2 into cancer cells enhances the adhesion and activation of natural killer cells, resulting in a reduction of peritoneal metastasis. ICAM-2 transfection using adenovirus vector might be an effective form of gene therapy for peritoneal metastasis of gastric cancer.     

Strategy for patients with cytology positive and peritoneal dissemination from gastric cancer

The aim of this study was to evaluate the strategy for patients with cytology positive and peritoneal dissemination from gastric cancer. Thirty eight of POCY1, three of P1, eight of P2 and thirty six of P3 from advanced gastric adenocarcinoma at staging laparoscopy were studied. Gastrectomy after staging laparoscopy was performed in 10 patients (Surgery group). NAC following gastrectomy after staging laparoscopy was performed in 31 patients (NAC group) in POCY1, P1. The overall response rate was 29%, twenty of the 31 patients (65%) in the NAC group revealed no free cancer cells at the operation. The overall 5-year survival rate in 41 patients of POCY1, P1 was 15%. There was a significant deference in the overall survival curves between Surgery and NAC groups. The overall 2-year survival rate in 44 patients of P2, P3 was 9%. NAC for patients with positive cytology could lead into free cancer cells at a high rate, but not to improve their prognoses. An intensive chemotherapy including intra-abdominal chemotherapy should be necessary for these patients.     

Modified pharmacokinetic modulating chemotherapy for progressive gastric cancer accompanied by peritoneal dissemination

Peritoneal dissemination is a major event in the development of gastric cancer. However, most patients with it have been excluded from clinical studies because they rarely have measurable lesions. We conducted an analysis to evaluate the efficacy and feasibility of modified pharmacokinetic modulating chemotherapy, for gastric cancer patients with peritoneal dissemination. Between May 2002 and April 2004, 10 patients were treated by modified pharmacokinetic modulating chemotherapy. This analysis was based on 10 consecutive chemotherapy-naive patients with confirmed peritoneal dissemination. This therapy regimen was repeated with a weekly schedule of MTX 100 mg/body, given as intraarterial infusion 1 h prior to a 24-hr infusion of 5-FU 500 mg/body. Simultaneously, enteric-coated tegafur/uracil (400 mg) was administered every day. The one-year overall survival rate was 50. 0%. The median survival time was 311 days. Grade 1 stomatitis and Grade 1/2 oral dryness were involved in 40% of the cases. No patient had to discontinue this therapy because of complications. Objective improvement of ascites was seen in all patients, and all patients could be treated at outpatient clinics. This regimen may be well-tolerated and of clinical benefit for patients with peritoneal dissemination of gastric cancer.     

Quantitative prognostic indicators of peritoneal dissemination of gastric cancer.

There are three classifications that describe the quantitative prognostic indicators of peritoneal dissemination for gastric cancer. The Japanese classification (P1, P2, and P3, Lyon classification, (stage I, II, stage III, and stage IV), and the Peritoneal Cancer Index (PCI). Carcinomatosis with limited extent (P1/ P2) corresponds to the PCI less than 13 and the stage I and II from Lyon classification. Carcinomatosis with large extent (P3) corresponds to PCI of 13 or larger and stage III and IV from Lyon classification. PCI enables one to describe the precise distribution of peritoneal dissemination. All three classifications correlate with prognosis. With regard to the surgical cytoreduction of the primary tumor and the peritoneal dissemination, Sugarbaker proposed the classification of completeness of cytoreduction (CCR). Patients with no macroscopic residual tumor had significantly better prognosis than those with residual disease. CCR is a valuable prognostic indicator after cytoreductive surgery.     

Sequential methotrexate and 5-fluorouracil therapy for gastric cancer patients with peritoneal dissemination: a retrospective study

Background. Most gastric cancer patients with peritoneal dissemination have been excluded from clinical studies because they usually have no measurable lesions. They also have a high risk of toxicity because of complications such as intestinal obstruction and ascites. We conducted a retrospective analysis to evaluate the efficacy and feasibility of sequential methotrexate (MTX) and 5-flurorouracil (5FU) therapy for this population. Methods. This analysis was based on 56 consecutive chemotherapy-naive patients with confirmed peritoneal dissemination of gastric cancer who were being treated with sequential MTX/5FU. The therapy comprised a weekly schedule of MTX 100 mg/m², given as a bolus infusion 3 h prior to a bolus infusion of 5FU 600 mg/m². Leucovorin 10 mg/m² was administered six times, every 6 h, starting 24 h after MTX administration. Results. Evidence of peritoneal dissemination was confirmed by laparotomy in 16 patients, by cytologic examination of ascites in 11 patients, and by clinical imaging in 29 patients (15 with ascites, 13 with intestinal obstruction; in 10 of the 29 patients, detection was by barium enema or computed tomography [CT] scan). Neutropenia of grade 3 or worse and anemia were observed in 8 (14%) and 10 (18%) of the 56 patients, respectively. There was one treatment-related death due to neutropenic sepsis. Of the 26 patients with measurable lesions, 9 showed a response (36%). The median survival time and median time to treatment failure were 259 days and 167 days, respectively. Objective improvement of ascites was seen in 13 of 26 patients (50%), including 5 with showed complete disappearance of ascites. Seven of the 15 patients (47%) with intestinal obstruction showed resolution, and 8 of the 21 patients (38%) who needed nutritional support before the treatment were free of that support for a median duration of 220 days after the completion of the treatment. Forty-seven of the 56 patients (84%) could be treated at outpatient clinics. Conclusions. This regimen may be of clinical benefit for patients with peritoneal dissemination of gastric cancer. Received: August 24, 2001 / Accepted: October 19, 2001     

VEGF receptor antisense therapy inhibits angiogenesis and peritoneal dissemination of human gastric cancer in nude mice

The efficacy of a phosphorothioate antisense oligonucleotide (ASO) for KDR/Flk-1 (KDR/Flk-1-ASO), an endothelial cell-specific vascular endothelial growth factor (VEGF) receptor, was investigated on the peritoneal dissemination and angiogenesis of a human gastric cancer cell line in nude mice. Green fluorescent protein (GFP)-transduced NUGC-4 (NUGC-4-GFP) human gastric cancer cells were implanted into the peritoneal cavity of nude mice. KDR/Flk-1-ASO, -SO, or phosphate-buffered saline was administrated from days 7 to 14, 200 microg/mouse, once a day. The mice were sacrificed on day 28. Disseminated peritoneal tumor nodules expressing GFP were visualized by fluorescence microscopy. KDR/Flk-1-ASO significantly decreased the extent of peritoneal dissemination of the tumors. The number of cells undergoing apoptosis was significantly increased in the KDR/Flk-1-ASO-treated tumors. Microvessel density was significantly reduced in the KDR/Flk-1-ASO-treated tumor nodules. The KDR/Flk-1 antisense strategy, therefore, decreases tumor dissemination apparently by inhibiting angiogenesis.