Emily K. Bergsland

Phase II, Randomized Trial Comparing Bevacizumab Plus Fluorouracil (FU)/Leucovorin (LV) With FU/LV Alone in Patients With Metastatic Colorectal Cancer

PURPOSE This phase II trial investigated the safety and efficacy of two doses of bevacizumab, a monoclonal antibody to vascular endothelial growth factor, plus fluorouracil (FU)/leucovorin (LV) versus FU/LV alone in patients with metastatic colorectal cancer. PATIENTS AND METHODS One hundred four previously untreated patients with measurable metastatic colorectal cancer were randomly assigned to one of the following three treatment groups: 36 to FU (500 mg/m(2))/LV (500 mg/m(2)) alone, 35 to FU/LV + low-dose bevacizumab (5 mg/kg every 2 weeks), and 33 to FU/LV + high-dose bevacizumab (10 mg/kg every 2 weeks). FU/LV was given weekly for the first 6 weeks of each 8-week cycle. RESULTS Compared with the FU/LV control arm, treatment with bevacizumab (at both dose levels) plus FU/LV resulted in higher response rates (control arm, 17%, 95% confidence interval [CI], 7% to 34%; low-dose arm, 40%, 95% CI, 24% to 58%; high-dose arm, 24%, 95% CI, 12% to 43%), longer median time to disease progression (control arm, 5.2 months, 95% CI, 3.5 to 5.6 months; low-dose arm, 9.0 months, 95% CI, 5.8 to 10.9 months; high-dose arm, 7.2 months, 95% CI, 3.8 to 9.2 months), and longer median survival (control arm, 13.8 months; 95% CI, 9.1 to 23.0 months; low-dose arm, 21.5 months, 95% CI, 17.3 to undetermined; high-dose arm, 16.1 months; 95% CI, 11.0 to 20.7 months). After cross-over, two of 22 patients had a partial response to bevacizumab alone. Thrombosis was the most significant adverse event and was fatal in one patient. Hypertension, proteinuria, and epistaxis were other potential safety concerns. CONCLUSION The encouraging results of this randomized trial support further study of bevacizumab 5 mg/kg plus chemotherapy as first-line therapy for metastatic colorectal cancer.

Benefits of targeting both pericytes and endothelial cells in the tumor vasculature with kinase inhibitors

Functions of receptor tyrosine kinases implicated in angiogenesis were pharmacologically impaired in a mouse model of pancreatic islet cancer. An inhibitor targeting VEGFRs in endothelial cells (SU5416) is effective against early-stage angiogenic lesions, but not large, well-vascularized tumors. In contrast, a kinase inhibitor incorporating selectivity for PDGFRs (SU6668) is shown to block further growth of end-stage tumors, eliciting detachment of pericytes and disruption of tumor vascularity. Importantly, PDGFRs were expressed only in perivascular cells of this tumor type, suggesting that PDGFR(+) pericytes in tumors present a complimentary target to endothelial cells for efficacious antiangiogenic therapy. Therapeutic regimes combining the two kinase inhibitors (SU5416 and SU6668) were more efficacious against all stages of islet carcinogenesis than either single agent. Combination of the VEGFR inhibitor with another distinctive kinase inhibitor targeting PDGFR activity (Gleevec) was also able to regress late-stage tumors. Thus, combinatorial targeting of receptor tyrosine kinases shows promise for treating multiple stages in tumorigenesis, most notably the often-intractable late-stage solid tumor.

Combined Analysis of Efficacy: The Addition of Bevacizumab to Fluorouracil/Leucovorin Improves Survival for Patients With Metastatic Colorectal Cancer

PURPOSE Bevacizumab (Avastin; Genentech Inc, South San Francisco, CA), a recombinant, humanized anti-vascular endothelial growth factor monoclonal antibody that inhibits tumor angiogenesis, has demonstrated survival benefit in patients with previously untreated metastatic colorectal cancer when combined with irinotecan/fluorouracil (FU)/leucovorin (LV; IFL). Three randomized clinical studies have evaluated bevacizumab in combination with FU/LV alone. A combined analysis of raw data from these studies was performed to better assess the efficacy of bevacizumab with FU/LV. PATIENTS AND METHODS The analysis used primary efficacy data from three independent studies, including 241 patients in a combined control group receiving either FU/LV or IFL and 249 patients receiving FU/LV/bevacizumab (5 mg/kg once every 2 weeks). The efficacy data included response rate, progression-free survival, and overall survival. RESULTS The median duration of survival was 17.9 months in the FU/LV/bevacizumab group, compared with 14.6 months in the combined control group, corresponding to a hazard ratio for death of 0.74 (P = .008). The median duration of progression-free survival was 8.8 months in the FU/LV/bevacizumab group, compared with 5.6 months in the combined control group, corresponding to a hazard ratio for disease progression of 0.63 (P < or = .0001). The addition of bevacizumab also improved the response rate (34.1% v 24.5%; P = .019). CONCLUSION The addition of bevacizumab to FU/LV provides a statistically significant and clinically relevant benefit to patients with previously untreated metastatic colorectal cancer.

Less is more, regularly: metronomic dosing of cytotoxic drugs can target tumor angiogenesis in mice.

Chemotherapeutic drugs, long the mainstay of cancer treatment, cause DNA damage and disrupt DNA replication in proliferating cells. Drug regimens have been designed to kill as many tumor cells as possible by treating with “maximum tolerated doses” (MTDs) of these cytotoxic agents. Side effects such as neurotoxicity and damage to proliferating cells in healthy tissues pose serious constraints on the use of chemotherapy. In an effort to balance toxicity with efficacy, a conventional dosing schedule calls for episodic application of a cytotoxic drug at or near the MTD, followed by periods of rest to allow normal tissues to recover. Many such chemotherapy regimens are initially efficacious, resulting in tumor regression or stabilization and prolonged survival. In rare cases, cures are achieved. In general, however, responses are short-lived, with relapses often marked by aggressive cancers that are resistant to the cytotoxic drug. Furthermore, the standard MTD regimen as a rule seriously impairs quality of life. The harsh side effects and the ultimate failures of most chemotherapies have fueled broad investigation of alternatives, including drugs that target not the transformed tumor cells themselves, but rather a genetically stable constituent cell type of tumors, the endothelial cells that form blood vessels. Angiogenesis, the process by which new blood vessels are formed, is a hallmark capability of cancer (1); a compelling body of evidence argues that tumor growth depends on the vasculature, and, in particular, on continuing angiogenesis (2, 3). More than two dozen new drugs that are in or soon to enter clinical trials appear to interfere with tumor angiogenesis (3, 4); there is considerable anticipation about their benefits in treating cancer. Now, two studies suggest a potentially complementary strategy of rescheduling the administration of classical cytotoxic drugs in order to target tumor endothelial cells. It is well established that tumor-associated endothelial cells proliferate during chronic angiogenesis in tumors, albeit at lower frequencies than the tumor cells themselves. Apparently because of their lower rate of cell division, replication of these endothelial cells is only weakly disrupted by the episodic regimens of standard chemotherapeutic protocols. In these two new studies, however, cytotoxic drugs were administered routinely, to target the slowly proliferating tumor endothelial cells and abrogate their apparent capability to repair and recover during the usual rest periods. Both groups worked with mice bearing subcutaneous tumors, and each presents data suggesting that “metronomic” dosing regimens—either continuous infusion or frequent administration without extended rest periods—could have real value in the clinic. Both also demonstrated combinatorial effects of such altered cytotoxic drug regimens with newer, more specific angiogenesis inhibitors.

Activity of Sunitinib in Patients With Advanced Neuroendocrine Tumors

PURPOSE Standard cytotoxic chemotherapy has limited efficacy in metastatic neuroendocrine tumor patients. Neuroendocrine tumors express vascular endothelial growth factor (VEGF) and its receptor (VEGFR). Sunitinib malate, an oral tyrosine kinase inhibitor, has activity against VEGFRs as well as platelet-derived growth factor receptors, stem-cell factor receptor, glial cell line-derived neurotrophic factor, and FMS-like tyrosine kinase-3. We evaluated the efficacy of sunitinib in a two-cohort, phase II study of advanced carcinoid and pancreatic neuroendocrine tumor patients. PATIENTS AND METHODS Patients were treated with repeated 6-week cycles of oral sunitinib (50 mg/d for 4 weeks, followed by 2 weeks off treatment). Patients were observed for response, survival, and adverse events. Patient-reported outcomes were assessed. RESULTS Among 109 enrolled patients, 107 received sunitinib (carcinoid, n = 41; pancreatic endocrine tumor, n = 66). Overall objective response rate (ORR) in pancreatic endocrine tumor patients was 16.7% (11 of 66 patients), and 68% (45 of 66 patients) had stable disease (SD). Among carcinoid patients, ORR was 2.4% (one of 41 patients), and 83% (34 of 41 patients) had SD. Median time to tumor progression was 7.7 months in pancreatic neuroendocrine tumor patients and 10.2 months in carcinoid patients. One-year survival rate was 81.1% in pancreatic neuroendocrine tumor patients and 83.4% in carcinoid patients. No significant differences from baseline in patient-reported quality of life or fatigue were observed during treatment. CONCLUSION Sunitinib has antitumor activity in pancreatic neuroendocrine tumors; its activity against carcinoid tumors could not be definitively determined in this nonrandomized study. Randomized trials of sunitinib in patients with neuroendocrine tumors are warranted.

Future Directions in the Treatment of Neuroendocrine Tumors: Consensus Report of the National Cancer Institute Neuroendocrine Tumor Clinical Trials Planning Meeting

Neuroendocrine tumors (NETs) arise from a variety of anatomic sites and share the capacity for production of hormones and vasoactive peptides. Because of their perceived rarity, NETs have not historically been a focus of rigorous clinical research. However, the diagnosed incidence of NETs has been increasing, and the estimated prevalence in the United States exceeds 100,000 individuals. The recent completion of several phase III studies, including those evaluating octreotide, sunitinib, and everolimus, has demonstrated that rigorous evaluation of novel agents in this disease is both feasible and can lead to practice-changing outcomes. The NET Task Force of the National Cancer Institute GI Steering Committee convened a clinical trials planning meeting to identify key unmet needs, develop appropriate study end points, standardize clinical trial inclusion criteria, and formulate priorities for future NET studies for the US cooperative group program. Emphasis was placed on the development of well-designed clinical trials with clearly defined efficacy criteria. Key recommendations include the evaluation of pancreatic NET separately from NETs of other sites and the exclusion of patients with poorly differentiated histologies from trials focused on low-grade histologies. Studies evaluating novel agents for the control of hormonal syndromes should avoid somatostatin analog washout periods when possible and should include quality-of-life end points. Because of the observed long survival after progression of many patients, progression-free survival is recommended as a feasible and relevant primary end point for both phase III studies and phase II studies where a delay in progression is expected in the absence of radiologic responses.

Phase II Study of Recombinant Human Endostatin in Patients With Advanced Neuroendocrine Tumors

PURPOSE Endostatin is a 20-kd proteolytic fragment of collagen XVIII that, in preclinical studies, has been shown to have antiangiogenic and antitumor activity. Both preclinical and human phase I studies of recombinant human endostatin (rhEndostatin) suggested activity in neuroendocrine tumors, which are known to be hypervascular. We therefore performed a multicenter phase II study of rhEndostatin in patients with carcinoid or pancreatic neuroendocrine tumors. PATIENTS AND METHODS Forty-two patients with advanced pancreatic endocrine tumors or carcinoid tumors were treated with rhEndostatin administered as a bid subcutaneous injection at a starting dose of 60 mg/m2/d. Steady-state trough levels were obtained after 6 weeks of therapy; patients who did not achieve a target therapeutic level of 300 ng/mL underwent dose escalation to 90 mg/m2/d. Patients were observed for evidence of toxicity, response, and survival. RESULTS rhEndostatin was associated with minimal toxicity. However, among 40 patients assessable for radiologic response, none experienced partial response to therapy, as defined by WHO criteria. The median steady-state trough level achieved after dose escalation was 331 ng/mL, within the postulated therapeutic range. CONCLUSION Treatment with rhEndostatin did not result in significant tumor regression in patients with advanced neuroendocrine tumors.

Immune Enhancement of Skin Carcinogenesis by CD4+ T Cells

In a transgenic model of multi-stage squamous carcinogenesis induced by human papillomavirus (HPV) oncogenes, infiltrating CD4+ T cells can be detected in both premalignant and malignant lesions. The lymph nodes that drain sites of epidermal neoplasia contain activated CD4+ T cells predominantly reactive toward Staphylococcal bacterial antigens. HPV16 mice deficient in CD4+ T cells were found to have delayed neoplastic progression and a lower incidence of tumors. This delay in carcinogenesis is marked by decreased infiltration of neutrophils, and reduced activity of matrix metalloproteinase-9, an important cofactor for tumor progression in this model. The data reveal an unexpected capability of CD4 T cells, whereby, proinflammatory CD4+ T cells, apparently responding to bacterial infection of dysplastic skin lesions, can inadvertently enhance neoplastic progression to invasive cancer.

Optimal timing of surgery after chemoradiation for advanced rectal cancer: preliminary results of a multicenter, nonrandomized phase II prospective trial.

Objective:To determine whether extending the interval between chemoradiation (CRT) and surgery, and administering additional chemotherapy during the waiting period has an impact on tumor response, CRT-related toxicity and surgical complications in patients with advanced rectal cancer. Background:Locally advanced rectal cancer is usually treated with preoperative CRT followed by surgery approximately 6 weeks later. The Timing of Rectal Cancer Response to Chemoradiation Consortium designed a prospective, multicenter, Phase II clinical trial to investigate extending the interval between CRT and surgery, and administering additional chemotherapy during the waiting period. Here, we present preliminary results of this trial, reporting the tumor response, CRT-related toxicity and surgical complications. Methods:Stage II and III rectal cancer patients were treated concurrently with 5-Fluorouracil (FU) and radiation for 5 to 6 weeks. Patients in study group (SG) 1 underwent total mesorectal excision (TME) 6 weeks later. Patients in SG2 with evidence of a clinical response 4 weeks after CRT received 2 cycles of modified FOLFOX-6 (mFOLFOX-6) followed by TME 3 to 5 weeks later. Tumor response, CRT-related toxicity and surgical complications were recorded. Results:One hundred and forty-four patients were accrued. One hundred and thirty-six (66, SG1; 70, SG2) were evaluated for CRT-related toxicity. One hundred and twenty-seven (60, SG1; 67, SG2) were assessed for tumor response and surgical complications. A similar proportion of patients completed CRT per protocol in both SGs, but the cumulative dose of sensitizing 5-FU and radiation was higher in SG2. CRT-related toxicity was comparable between SGs. Average time from CRT-to-surgery was 6 (SG1) and 11 weeks (SG2). Pathologic complete response (pCR) was 18% (SG1) and 25% (SG2). Postoperative complications were similar between SGs. Conclusions:Intense neoadjuvant therapy consisting of CRT followed by additional chemotherapy (mFOLFOX-6), and delaying surgery may result in a modest increase in pCR rate without increasing complications in patients undergoing TME for locally advanced rectal cancer.

Phase II Trial of Sunitinib in Patients With Metastatic Colorectal Cancer After Failure of Standard Therapy

PURPOSE Sunitinib is an oral, multitargeted receptor tyrosine kinase inhibitor of the vascular endothelial growth factor receptor and multiple other growth factor receptors. We assessed the safety and efficacy of sunitinib in patients with metastatic colorectal cancer after failure of standard therapy. PATIENTS AND METHODS Eighty-four patients were enrolled onto this two-stage phase II trial and were stratified by whether they had received prior bevacizumab (n = 43) or not (n = 41). Treatment comprised sunitinib 50 mg orally daily for 4 weeks, followed by 2 weeks off treatment, in repeated 6-week cycles. RESULTS By Response Evaluation Criteria in Solid Tumors criteria, one patient, who was in the prior bevacizumab cohort, achieved a partial response, and 13 patients (two in the prior bevacizumab cohort and 11 in the no prior bevacizumab cohort) achieved stable disease lasting > or = 22 weeks. Median time to progression in the prior bevacizumab and bevacizumab-naïve cohorts was 2.2 months (95% CI, 1.9 to 2.3 months) and 2.5 months (95% CI, 2.3 to 3.1 months), respectively, whereas median overall survival time was 7.1 months (95% CI, 4.9 to 10.6 months) and 10.2 months (95% CI, 8.2 to 15.3 months), respectively. The most common adverse events were fatigue, diarrhea, nausea, vomiting, and anorexia. Twenty-six patients (32%) required dose reduction to 37.5 mg/d, and one patient required dose reduction to 25 mg/d. CONCLUSION Sunitinib did not demonstrate a meaningful single-agent objective response rate in colorectal cancer refractory to standard chemotherapy. However, the mechanisms of action and acceptable safety profile of sunitinib warrant further study in combination with standard regimens for metastatic colorectal cancer.