Antiangiogenic therapy in oncology: current status and future directions.

Angiogenesis, the formation of new blood vessels from pre-existing vessels, has been validated as a target in several tumour types through randomised trials, incorporating vascular endothelial growth factor (VEGF) pathway inhibitors into the therapeutic armoury. Although some tumours such as renal cell carcinoma, ovarian and cervical cancers, and pancreatic neuroendocrine tumours are sensitive to these drugs, others such as prostate cancer, pancreatic adenocarcinoma, and melanoma are resistant. Even when drugs have yielded significant results, improvements in progression-free survival, and, in some cases, overall survival, are modest. Thus, a crucial issue in development of these drugs is the search for predictive biomarkers-tests that predict which patients will, and will not, benefit before initiation of therapy. Development of biomarkers is important because of the need to balance efficacy, toxicity, and cost. Novel combinations of these drugs with other antiangiogenics or other classes of drugs are being developed, and the appreciation that these drugs have immunomodulatory and other modes of action will lead to combination regimens that capitalise on these newly understood mechanisms.

Colon cancer cells escape 5FU chemotherapy-induced cell death by entering stemness and quiescence associated with the c-Yes/YAP axis.

PURPOSE: Metastasis and drug resistance are the major limitations in the survival and management of patients with cancer. This study aimed to identify the mechanisms underlying HT29 colon cancer cell chemoresistance acquired after sequential exposure to 5-fluorouracil (5FU), a classical anticancer drug for treatment of epithelial solid tumors. We examined its clinical relevance in a cohort of patients with colon cancer with liver metastases after 5FU-based neoadjuvant chemotherapy and surgery. RESULTS: We show that a clonal 5F31 cell population, resistant to 1 µmol/L 5FU, express a typical cancer stem cell-like phenotype and enter into a reversible quiescent G0 state upon reexposure to higher 5FU concentrations. These quiescent cells overexpressed the tyrosine kinase c-Yes that became activated and membrane-associated upon 5FU exposure. This enhanced signaling pathway induced the dissociation of the Yes/YAP (Yes-associated protein) molecular complex and depleted nuclear YAP levels. Consistently, YES1 silencing decreased nuclear YAP accumulation and induced cellular quiescence in 5F31 cells cultured in 5FU-free medium. Importantly, YES1 and YAP transcript levels were higher in liver metastases of patients with colon cancer after 5FU-based neoadjuvant chemotherapy. Moreover, the YES1 and YAP transcript levels positively correlated with colon cancer relapse and shorter patient survival (P < 0.05 and P < 0.025, respectively). CONCLUSIONS: We identified c-Yes and YAP as potential molecular targets to eradicate quiescent cancer cells and dormant micrometastases during 5FU chemotherapy and resistance and as predictive survival markers for colon cancer.

Vascular endothelial growth factor targeted therapy in the perioperative setting: implications for patient care.

Vascular endothelial growth factor (VEGF) targeted therapy, either alone or in combination with chemotherapy, has become the standard of care in several solid tumours, including colorectal cancer, renal-cell carcinoma, breast cancer, non-small-cell lung cancer, and glioblastoma. VEGF is crucial in the process of angiogenesis and wound healing and, thus, its inhibition has the potential to affect wound healing in patients undergoing surgery. In this review, we summarise the data available on the use of VEGF-targeted therapies, and their effect on perioperative wound complications. Surgery in patients receiving VEGF-targeted therapies seems to be safe when an appropriate interval of time is allowed between surgical procedures and treatment. Recommendations regarding this interval are provided in a disease and agent site-specific manner. We also discuss complications arising from the use of VEGF-directed therapies that might require surgical intervention and the considerations important in their management. At this juncture, safety data on the use of VEGF-targeted therapies in the perioperative period are sparse, and investigators are urged to continue to study this issue prospectively in current and future clinical trials to establish firm guidelines.

Phase II trial of neoadjuvant bevacizumab, capecitabine, and radiotherapy for locally advanced rectal cancer.

PURPOSE: We designed this Phase II trial to assess the efficacy and safety of the addition of bevacizumab to concurrent neoadjuvant capecitabine-based chemoradiation in locally advanced rectal cancer. METHODS: Between April 2004 and December 2007, 25 patients with clinically staged T3N1 (n = 20) or T3N0 (n = 5) rectal cancer received neoadjuvant therapy with radiotherapy (50.4 Gy in 28 fractions over 5.5 weeks), bevacizumab every 2 weeks (3 doses of 5 mg/kg), and capecitabine (900 mg/m(2) orally twice daily only on days of radiation), followed by surgical resection a median of 7.3 weeks later. RESULTS: Procedures included abdominoperineal resection (APR; 6 patients), proctectomy with coloanal anastamosis (8 patients), low anterior resection (10 patients), and local excision (1 patient). Eight (32%) of 25 patients had a pathologic complete response, and 6 (24%) of 25 had <10% viable tumor cells in the specimen. No patient had Grade 3 hand-foot syndrome, gastrointestinal toxicity, or significant hematologic toxicity. Three wound complications required surgical intervention (one coloanal anastamostic dehiscence requiring completion APR and two perineal wound dehiscences after initial APR). Five minor complications occurred that resolved without operative intervention. With a median follow-up of 22.7 months (range, 4.5-32.4 months), all patients were alive; one patient has had a recurrence in the pelvis (2-year actuarial rate, 6.2%) and 3 had distant recurrences. CONCLUSIONS: The addition of bevacizumab to neoadjuvant chemoradiation resulted in encouraging pathologic complete response without an increase in acute toxicity. The impact of bevacizumab on perineal wound and anastamotic healing due to concurrent bevacizumab requires further study.

Clinical and pathologic predictors of locoregional recurrence, distant metastasis, and overall survival in patients treated with chemoradiation and mesorectal excision for rectal cancer.

OBJECTIVES: To identify predictive factors for locoregional recurrence (LR), distant metastasis (DM), and overall survival (OS) in patients treated with chemoradiation and surgery for rectal cancer. METHODS: Between 1989 and 2001, 470 patients with rectal cancer were treated with preoperative (89%) or postoperative (11%) chemoradiation and mesorectal excision. Median radiation dose was 45 Gy; 97% received concurrent infusional 5-fluorouracil, and 65% received adjuvant chemotherapy. Median follow-up interval was 5.7 years. RESULTS: The 5-year rates of freedom from LR, freedom from DM, and OS were 90%, 79%, and 80%, respectively. On univariate analysis, significant predictors of LR were female sex, clinical T stage, pathologic T and N stages, and positive radial margin. Significant univariate predictors of DM were circumferential extent of tumor, tumor immobility, lymphovascular invasion, perineural involvement, and pathologic T and N stages. Significant univariate predictors of lower OS were age, circumferential extent of tumor, shorter distance from anal verge, tumor size, tumor immobility, anal canal involvement, lymphovascular invasion, perineural involvement, positive radial margin, and pathologic T and N stages. On Cox multivariate analysis, female sex and pathologic T and N stages independently predicted for LR; pathologic T and N stages independently predicted for DM; and age, circumferential extent of tumor, positive radial margin, and pathologic T and N stages independently predicted for lower OS. CONCLUSIONS: Pathologic T and N stages significantly predicted for all 3 end points (LR, DM and OS) on multivariate analysis. Investigations of more aggressive adjuvant chemotherapy appear warranted for pathologic stage T3/T4 or N1/2 rectal cancer.

Roles of nitric oxide synthase inhibition and vascular endothelial growth factor receptor-2 inhibition on vascular morphology and function in an in vivo model of pancreatic cancer.

PURPOSE: Both nitric oxide (NO) and vascular endothelial growth factor (VEGF) mediate tumor vascular function. Because these molecules regulate one another's expression, we hypothesized that NO synthase (NOS) inhibition produces effects comparable to those of anti-VEGF therapy on human pancreatic cancer xenografts. EXPERIMENTAL DESIGN: L3.6pl human pancreatic cancer cells were s.c. implanted in nude mice. On day 6, mice were randomized to receive (a) PBS (control), (b) DC101 [VEGF receptor 2 (VEGFR-2) antibody] by i.p. injection, (c) N-nitro-l-arginine (NNLA; NOS inhibitor) in the drinking water, or (d) both DC101 and NNLA. Mice were killed on day 20. RESULTS: DC101 and NNLA as single agents inhibited tumor growth by approximately 50% to 60% (P < 0.008 for both). Furthermore, combined therapy inhibited mean tumor growth by 89% (P < 0.008). Combined inhibition of VEGFR-2 and NOS also decreased mean vessel counts by 65% (P < 0.03) and vessel area by 80% versus controls (P < 0.001). In contrast to DC101 where vessel diameter was similar to control, NNLA decreased mean vessel diameter by 42% (P < 0.001). NNLA also led to a 54% (P < 0.03) decrease in tumor uptake of the perfusion marker Hoechst 33342 versus controls whereas DC101 decreased Hoechst 33342 staining by 43% (P < 0.03). The combination of inhibitors decreased perfusion by 73% (P < 0.03). CONCLUSIONS: Although VEGFR-2 can mediate NOS activity, the combination of VEGFR-2 and NOS inhibition significantly increased the antivascular effect over single agent therapy. The addition of NOS inhibition led to an even further alteration of tumor vessel morphology and vascular perfusion compared with VEGFR-2 blockade, suggesting that NO and VEGFR-2 have distinct but complementary effects on the tumor vasculature.

Phase I trial evaluating the safety of bevacizumab with concurrent radiotherapy and capecitabine in locally advanced pancreatic cancer.

PURPOSE: To study the safety of bevacizumab with capecitabine-based chemoradiotherapy. PATIENTS AND METHODS: Patients with inoperable pancreatic adenocarcinoma received bevacizumab 2 weeks before radiotherapy (50.4 Gy treating the primary tumor and gross adenopathy), every 2 weeks during radiotherapy (12 patients each at 2.5, 5.0, 7.5, and 10 mg/kg), and after radiotherapy until disease progression. Capecitabine was administered on days 14 through 52 (650 mg/m2 orally twice daily for the first six patients; 825 mg/m2 for the remaining patients). RESULTS: Significant acute gastrointestinal (43% grade 2; 4% grade 3), hand and foot syndrome (21% grade 2), and transient hematologic (8% grade 3 or greater) events were uncommon with protocol mandated dose reductions of capecitabine grade 2 toxicity (43% of patients). Among the first 30 patients treated, three patients had tumor-associated bleeding duodenal ulcers, and one had a contained duodenal perforation. No additional bleeding events occurred among the final 18 patients after patients with duodenal involvement by tumor were excluded. Nine (20%) of 46 assessable patients had confirmed partial responses until distant progression for a median of 6.2 months. Four patients have undergone pancreaticoduodenectomy without perioperative complication. The median survival was 11.6 months (95% CI, 9.6 to 13.6), from the start of protocol therapy. CONCLUSION: Concurrent bevacizumab did not significantly increase the acute toxicity of a relatively well-tolerated chemoradiotherapy regimen. However, ulceration and bleeding in the radiation field possibly related to bevacizumab occurred when tumor involved the duodenal mucosa. The encouraging efficacy end points suggest that the further study of bevacizumab with chemoradiotherapy is warranted.

Angiogenesis and antiangiogenic therapy of colon cancer liver metastasis.

The fact that tumor growth and metastatic spread relies on angiogenesis has been widely proven and accepted. The understanding of cancer biology and metastasis formation has led to the development of new therapeutic approaches that target tumor biology. The survival and establishment of metastatic lesions depend on a shift in the normal balance of proangiogenic and antiangiogenic factors that favor angiogenesis. Colorectal cancer is one of the leading cancer deaths worldwide. Angiogenesis has been associated with colon cancer progression and metastatic spread, thereby significantly affecting patient survival. New experimental approaches that inhibit angiogenic processes have demonstrated promising antineoplastic effects on metastatic colorectal cancer and are partially being investigated in clinical trials. This review focuses on angiogenesis in colorectal cancer metastasis formation as a target for antiangiogenic therapy, describing the experience from experimental studies and current clinical trials.