The Promise for Histone Methyltransferase Inhibitors for Epigenetic Therapy in Clinical Oncology: A Narrative Review.

Epigenetic processes are essential for normal development and the maintenance of tissue-specific gene expression in mammals. Changes in gene expression and malignant cellular transformation can result from disruption of epigenetic mechanisms, and global disruption in the epigenetic landscape is a key feature of cancer. The study of epigenetics in cancer has revealed that human cancer cells harbor both genetic alterations and epigenetic abnormalities that interplay at all stages of cancer development. Unlike genetic mutations, epigenetic aberrations are potentially reversible through epigenetic therapy, providing a therapeutically relevant treatment option. Histone methyltransferase inhibitors are emerging as an epigenetic therapy approach with great promise in the field of clinical oncology. The recent accelerated approval of the enhancer of zeste homolog 2 (EZH2; also known as histone-lysine N-methyltransferase EZH2) inhibitor tazemetostat for metastatic or locally advanced epithelioid sarcoma marks the first approval of such a compound for the treatment of cancer. Many other histone methyltransferase inhibitors are currently in development, some of which are being tested in clinical studies. This review focuses on histone methyltransferase inhibitors, highlighting their potential in the treatment of cancer. We also discuss the role for such epigenetic drugs in overcoming epigenetically driven drug resistance mechanisms, and their value in combination with other therapeutic approaches such as immunotherapy.

MAVERICC, a Randomized, Biomarker-stratified, Phase II Study of mFOLFOX6-Bevacizumab versus FOLFIRI-Bevacizumab as First-line Chemotherapy in Metastatic Colorectal Cancer.

PURPOSE: MAVERICC compared the efficacy and safety of modified leucovorin/5-fluorouracil/oxaliplatin plus bevacizumab (mFOLFOX6-BV) with leucovorin/5-fluorouracil/irinotecan plus bevacizumab (FOLFIRI-BV) in patients with previously untreated metastatic colorectal cancer (mCRC).Patients and Methods: MAVERICC was a global, randomized, open-label, phase II study. Primary objectives were to assess associations between (i) excision repair cross-complementing 1 (ERCC1) expression with progression-free survival (PFS), and (ii) plasma VEGF A (VEGF-A) with PFS in patients with previously untreated mCRC receiving mFOLFOX6-BV or FOLFIRI-BV. Before randomization, patients were stratified by tumoral ERCC1/ß-actin mRNA expression level and region. RESULTS: Of 376 enrolled patients, 188 each received mFOLFOX6-BV and FOLFIRI-BV. PFS and overall survival (OS) were comparable between FOLFIRI-BV and mFOLFOX6-BV, with numerically higher PFS [HR = 0.79; 95% CI (confidence interval): 0.61-1.01; P = 0.06] and OS (HR = 0.76; 95% CI: 0.56-1.04; P = 0.09) observed for FOLFIRI-BV. In the high ERCC1 subgroup, PFS and OS were comparable between treatment groups (PFS, HR = 0.84; 95% CI: 0.56-1.26; P = 0.40; OS, HR = 0.80; 95% CI: 0.51-1.26; P = 0.33). Across treatment groups, high plasma VEGF-A levels (>5.1 pg/mL) were observed with shorter PFS (HR = 1.19; 95% CI: 0.93-1.53; P = 0.17) and significantly shorter OS (HR = 1.64; 95% CI: 1.20-2.24; P < 0.01) versus low levels (≤5.1 pg/mL). Safety findings for FOLFIRI-BV or mFOLFOX6-BV were comparable with those reported previously. CONCLUSIONS: First-line FOLFIRI-BV and mFOLFOX6-BV had comparable PFS and OS, similar to results in patients with high baseline tumor ERCC1 levels. There were no new safety signals with these bevacizumab-containing regimens.

Phase II Randomized Trial of Sequential or Concurrent FOLFOXIRI-Bevacizumab Versus FOLFOX-Bevacizumab for Metastatic Colorectal Cancer (STEAM).

BACKGROUND: First-line treatment for metastatic colorectal cancer (mCRC) typically entails a biologic such as bevacizumab (BEV) with 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX) or 5-fluorouracil/leucovorin/irinotecan (FOLFIRI). STEAM (NCT01765582) assessed the efficacy of BEV plus FOLFOX/FOLFIRI (FOLFOXIRI), administered concurrently (cFOLFOXIRI-BEV) or sequentially (sFOLFOXIRI-BEV, FOLFOX-BEV alternating with FOLFIRI-BEV), versus FOLFOX-BEV for mCRC. PATIENTS AND METHODS: Patients with previously untreated mCRC (n = 280) were randomized 1:1:1 to cFOLFOXIRI-BEV, sFOLFOXIRI-BEV, or FOLFOX-BEV and treated with 4-6-month induction followed by maintenance. Coprimary objectives were overall response rate (ORR; first-line cFOLFOXIRI-BEV vs. FOLFOX-BEV) and progression-free survival (PFS; pooled first-line cFOLFOXIRI-BEV and sFOLFOXIRI-BEV vs. FOLFOX-BEV). Secondary/exploratory objectives included overall survival (OS), liver resection rates, biomarker analyses, and safety. RESULTS: ORR was 72.0%, 72.8%, and 62.1% and median PFS was 11.9, 11.4, and 9.5 months with cFOLFOXIRI-BEV, sFOLFOXIRI-BEV, and FOLFOX-BEV, respectively. OS was similar between arms. ORR between cFOLFOXIRI-BEV and FOLFOX-BEV did not significantly differ (p = .132); thus, the primary ORR endpoint was not met. cFOLFOXIRI-BEV and sFOLFOXIRI-BEV numerically improved ORR and PFS, regardless of RAS status. Median PFS was higher with pooled concurrent and sequential FOLFOXIRI-BEV versus FOLFOX-BEV (11.7 vs. 9.5 months; hazard ratio, 0.7; 90% confidence interval, 0.5-0.9; p < .01). Liver resection rates were 17.2% (cFOLFOXIRI-BEV), 9.8% (sFOLFOXIRI-BEV), and 8.4% (FOLFOX-BEV). Grade ≥ 3 treatment-emergent adverse events (TEAEs) were observed in 91.2% (cFOLFOXIRI-BEV), 86.7% (sFOLFOXIRI-BEV), and 85.6% (FOLFOX-BEV) of patients, with no increase in serious chemotherapy-associated TEAEs. CONCLUSION: cFOLFOXIRI-BEV and sFOLFOXIRI-BEV were well tolerated with numerically improved ORR, PFS, and liver resection rates versus FOLFOX-BEV, supporting triplet chemotherapy plus BEV as a first-line treatment option for mCRC. IMPLICATIONS FOR PRACTICE: The combination of first-line FOLFIRI with FOLFOX and bevacizumab (concurrent FOLFOXIRI-BEV) improves clinical outcomes in patients with metastatic colorectal cancer (mCRC) relative to FOLFIRI-BEV or FOLFOX-BEV, but it is thought to be associated with increased toxicity. Alternating treatment of FOLFOX and FOLFIRI (sequential FOLFOXIRI-BEV) could improve tolerability. In the phase II STEAM trial, which is the largest study of FOLFOXIRI-BEV in patients in the U.S., it was found that both concurrent and sequential FOLFOXIRI-BEV are active and well tolerated in patients with previously untreated mCRC, supporting the use of these regimens as potential first-line treatment options for this population.

Neoadjuvant breast cancer treatment as a sensitive setting for trastuzumab biosimilar development and extrapolation.

AIMS: Identify sensitive end points and populations for similarity studies of trastuzumab and biosimilar monoclonal antibodies. METHODS: We performed meta-analyses of trastuzumab clinical trials data: overall response rate (ORR) and progression-free survival in metastatic breast cancer (MBC), and total pathologic complete response (tpCR) and event-free survival in the neoadjuvant setting. Fitted models predicted the maximum loss in long-term efficacy for different similarity trial designs. Immunogenicity rates were investigated in different early breast cancer (EBC) study phases. RESULTS: Using the same equivalence margins for ORR (MBC) and tpCR (EBC), the predicted maximum loss in long-term efficacy with a biosimilar candidate versus the reference product is smaller for tpCR than for ORR. In EBC this predicted loss could be controlled with feasible patient numbers for a typical clinical trial. Analyses suggested that a treatment-free follow-up phase is preferable for immunogenicity characterization. CONCLUSION: Treatment of patients with neoadjuvant breast cancer represents a sensitive setting for establishing biosimilarity of efficacy and immunogenicity. tpCR is a sensitive end point in this setting to establish biosimilarity between a biosimilar candidate and its reference product.

Phase 2 trial of linifanib (ABT-869) in patients with unresectable or metastatic hepatocellular carcinoma.

BACKGROUND: The efficacy and safety of linifanib (ABT-869), a selective inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptor tyrosine kinases, were assessed in this phase 2, single-arm, open-label, multicenter trial. METHODS: Eligible patients had unresectable or metastatic hepatocellular carcinoma and had received ≤ 1 prior systemic therapy. Patients received oral linifanib at a fasting dose of 0.25 mg/kg,. The primary endpoint was the progression-free rate at 16 weeks. Tumor response was assessed every 8 weeks. Secondary endpoints included the time to disease progression, overall survival, and objective response rate. Safety was also assessed. RESULTS: Of the 44 patients enrolled, the majority were Asian (89%), had received no prior systemic therapy (82%), had Child-Pugh class A hepatic function (86%), and had hepatitis B virus infection (61%). The estimated progression-free rate at 16 weeks was 31.8% (34.2% for patients with Child-Pugh class A hepatic function), the estimated objective response rate was 9.1% (10.5% for patients with Child-Pugh class A hepatic function), the median time to disease progression was 3.7 months (3.7 months for patients with Child-Pugh class A hepatic function), and the median overall survival was 9.7 months (10.4 months for patients with Child-Pugh class A hepatic function). The most common linifanib-related adverse events were diarrhea (55%) and fatigue (52%). The most common linifanib-related grade 3/4 adverse events were hypertension (25%) and fatigue (14%). Serum levels of biomarkers cancer antigen (CA) 125, cytokeratin fragment (CYFRA)21.1, and protein induced by vitamin K absence or antagonist II (PIVKA) demonstrated potential as prognostic indicators of patient response or outcome. CONCLUSIONS: Single-agent linifanib was found to be clinically active in patients with advanced hepatocellular carcinoma, with an acceptable safety profile.

Phase 2 trial of linifanib (ABT-869) in patients with advanced renal cell cancer after sunitinib failure.

PURPOSE: This study assessed the efficacy and safety of linifanib in patients with advanced renal cell carcinoma (RCC) who were previously treated with sunitinib. MATERIALS AND METHODS: This open-label, multicentre, phase 2 trial of oral linifanib 0.25 mg/kg/day enrolled patients who had prior nephrectomy and adequate organ function. The primary end-point was objective response rate (ORR) per response evaluation criteria in solid tumors (RECIST) by central imaging. Secondary end-points were progression-free survival (PFS), overall survival (OS) and time to progression (TTP). Safety was also assessed. RESULTS: Fifty-three patients, median age 61 years (range 40-80) were enrolled (August 2007 to October 2008) across 12 North-American centres. Median number of prior therapies was 2 (range 1-4); 43 patients (81%) had clear-cell histology. ORR was 13.2%, median PFS was 5.4 months (95% Confidence Interval (CI): 3.6, 6.0) and TTP was the same; median OS was 14.5 months (95% CI: 10.8, 24.1). The most common treatment-related adverse events (AEs) were diarrhoea (74%), fatigue (74%) and hypertension (66%), and the most common treatment-related Grade 3/4 AE was hypertension (40%). CONCLUSIONS: Linifanib demonstrated clinically meaningful activity in patients with advanced RCC after sunitinib failure. At 0.25 mg/kg/day, significant dose modifications were required. An alternative, fixed-dosing strategy is being evaluated in other trials.

Phase 2 trial of Linifanib (ABT-869) in patients with advanced non-small cell lung cancer.

INTRODUCTION: This study assessed activity and safety of linifanib (ABT-869), a selective inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptors, in patients with locally advanced or metastatic non-small cell lung cancer. METHODS: In this open-label trial (NCT00517790), patients who received one to two prior lines of systemic therapy were randomized to oral linifanib 0.10 mg/kg (low dose) or 0.25 mg/kg (high dose) once daily. Tumor responses were assessed by independent central imaging review every 8 weeks. The primary end point was progression-free rate at 16 weeks. Secondary end points included objective response rate, time to progression, progression-free survival, and overall survival. Safety was also assessed. RESULTS: Between August 2007 and October 2008, 139 patients were enrolled; 60% had two or more prior regimens, and 88% had nonsquamous cell carcinoma. The objective response rate (low dose and high dose) was 5.0% (3.1 and 6.8%), progression-free rate at 16 weeks was 33.1% (32.3 and 33.8%), median time to progression was 3.6 months (3.6 and 3.7 months), median progression-free survival was 3.6 months (3.5 and 3.6 months), and median overall survival was 9.0 months (10.0 and 8.3 months). The most common linifanib-related adverse events were fatigue (42%), decreased appetite (38%), hypertension (37%), diarrhea (32%), nausea (27%), palmar-plantar erythrodysesthesia (24%), and proteinuria (22%). These events were more common in the high-dose group. The most common linifanib-related grade 3 or 4 adverse event was hypertension (14%). CONCLUSIONS: Linifanib is active in advanced non-small cell lung cancer as second- or third-line therapy. Increased adverse event rates were observed at the high dose of linifanib.

Randomized phase II study of bevacizumab in combination with chemotherapy in previously untreated extensive-stage small-cell lung cancer: results from the SALUTE trial.

PURPOSE: Because of promising efficacy signals in single-arm studies, a placebo-controlled, double-blind, randomized phase II trial was designed to assess the efficacy and safety of adding bevacizumab to first-line standard chemotherapy for treatment of extensive-stage small-cell lung cancer (SCLC). PATIENTS AND METHODS: Patients with SCLC were randomly assigned to receive bevacizumab or placebo, with cisplatin or carboplatin plus etoposide, for four cycles followed by single-agent bevacizumab or placebo until progression or unacceptable toxicity. The primary end point was progression-free survival (PFS). RESULTS: Fifty-two patients were randomly assigned to the bevacizumab group and 50 to the placebo group; 69% versus 66%, respectively, completed four cycles of therapy. Median PFS was higher in the bevacizumab group (5.5 months) than in the placebo group (4.4 months; hazard ratio [HR], 0.53; 95% CI, 0.32 to 0.86). Median overall survival (OS) was similar for both groups (9.4 v 10.9 months for bevacizumab and placebo groups, respectively), with an HR of 1.16 (95% CI, 0.66 to 2.04). Overall response rates were 58% (95% CI, 43% to 71%) for the bevacizumab group and 48% (95% CI, 34% to 62%) for the placebo group. Median duration of response was 4.7 months for the bevacizumab group and 3.2 months for the placebo group. In the bevacizumab and placebo groups, 75% versus 60% of patients, respectively, experienced one or more grade 3 or higher adverse events. No new or unexpected safety signals for bevacizumab were observed. CONCLUSION: The addition of bevacizumab to cisplatin or carboplatin plus etoposide for treatment of extensive-stage SCLC improved PFS, with an acceptable toxicity profile. However, no improvement in OS was observed.

Safety and efficacy of combining sunitinib with bevacizumab + paclitaxel/carboplatin in non-small cell lung cancer.

INTRODUCTION: Bevacizumab (B) improves survival of patients with metastatic, nonsquamous non-small cell lung cancer. Based on encouraging results from preclinical studies combining B with sunitinib (S), a phase II, randomized, open-label study (Study Assessing the Blockade of both VEGF Receptor and ligand to enhance Efficacy in Lung) was initiated to assess clinical outcomes of adding S to paclitaxel (P)/carboplatin (C) + B (PCB) for first-line treatment of locally advanced, metastatic, or recurrent nonsquamous non-small cell lung cancer. METHODS: Study enrollment was to occur in three phases. In the first phase, patients received PC + B (15 mg/kg every 3 weeks), +/-S (25 mg daily, 2 weeks on, 1 week off). If tolerated, the second phase would include a third cohort receiving 37.5 mg S. The third phase would consist of PCB +/- highest tolerable dose S. RESULTS: Between March 2007 and January 2008, 26 patients were randomized to receive PCB and 30 to PCB + S 25 mg. Because of poor tolerability, none of the patients were escalated to 37.5 mg S. Median treatment duration was 10.3 weeks for PCB and 6.0 weeks for PCB + S. Thirty-five percent of patients on PCB + S required S dose reduction, 52% required S treatment interruption, and 59% discontinued S because of adverse events, most frequently hematologic events (neutropenia, thrombocytopenia, and leukopenia) and fatigue. Patients receiving PCB + S required more B interruptions (38% versus 19% for PCB) and discontinuation (52% versus 35%) because of adverse events. Survival data were limited by small sample sizes and limited treatment duration. Overall survival was not mature at time of analysis: median 6.6 months for PCB + S and not reached for PCB. Two out of 25 efficacy-evaluable patients randomized to the PCB + S cohort had confirmed partial responses, compared with 5 of 19 randomized to the PCB cohort. CONCLUSIONS: The addition of S to PCB was not well tolerated because of toxicities. This combination should not be studied further at these doses and schedules.

Randomized phase II study of erlotinib combined with bevacizumab compared with bevacizumab alone in metastatic renal cell cancer.

PURPOSE: Bevacizumab (Bev) has clinical activity in advanced renal cell carcinoma (RCC), and, when combined with erlotinib (Erl), has shown encouraging objective response rate (ORR) and progression-free survival (PFS). We performed a phase II, randomized, double-blind, multicenter, placebo-controlled trial to assess whether Erl provides additional clinical benefit with regard to PFS and ORR when combined with Bev in first-line treatment of metastatic RCC. PATIENTS AND METHODS: One hundred four patients received intravenous Bev (10 mg/kg) every 2 weeks in combination with oral Erl (150 mg) or placebo daily. Patients were treated until progression or toxicity. RESULTS: A landmark analysis was performed 9 months after enrollment was completed (median follow-up, 9.8 months). Sixty-five patients had discontinued therapy; time to study discontinuation did not differ between the two treatment groups. The median PFS was 9.9 months (Bev + Erl [B+E]) versus 8.5 months (Bev; hazard ratio = 0.86; 95% CI, 0.5 to 1.49; P = .58). ORR (complete plus partial) was 14% (B+E) versus 13% (Bev). One complete response occurred in the B+E group. Median survival was 20 months for B+E but not reached for Bev. The most common grade 3/4 adverse events (> 5% of patients) were hypertension, rash, proteinuria, diarrhea, and hemorrhage. One treatment-related death occurred on study (GI perforation, B+E group). CONCLUSION: The addition of Erl to Bev was well tolerated, but did not provide additional clinical benefit compared with Bev alone. Bev has encouraging clinical activity for previously untreated metastatic RCC patients.

Arterial thromboembolic events in patients with metastatic carcinoma treated with chemotherapy and bevacizumab.

BACKGROUND: Although combination treatment with bevacizumab (humanized monoclonal antibody against vascular endothelial growth factor) and chemotherapy improves survival of patients with various metastatic carcinomas, an increased risk of arterial thromboembolic events has been observed in some trials. We characterized this risk by performing post hoc analyses of randomized controlled trials that evaluated combination treatment with bevacizumab and chemotherapy versus chemotherapy alone. Low-dose aspirin was permitted in these trials, and its safety was also analyzed. METHODS: Data were pooled from five randomized controlled trials that included a total of 1745 patients with metastatic colorectal, breast, or non-small-cell lung carcinoma. The risk of an arterial or venous thromboembolic event was assessed by simple incidence rates, rates per 100 person-years, and/or hazard ratios (HRs). The association between patient characteristics and risk of an arterial thromboembolic event was investigated primarily by Cox proportional hazards regression. The relationship between low-dose aspirin and bleeding was explored by incidence rates and rates per 100 person-years. RESULTS: Combined treatment with bevacizumab and chemotherapy, compared with chemotherapy alone, was associated with increased risk for an arterial thromboembolic event (HR = 2.0, 95% confidence interval [CI] = 1.05 to 3.75; P = .031) but not for a venous thromboembolic event (HR = 0.89, 95% CI = 0.66 to 1.20; P = .44). The absolute rate of developing an arterial thromboembolism was 5.5 events per 100 person-years for those receiving combination therapy and 3.1 events per 100 person-years for those receiving chemotherapy alone (ratio = 1.8, 95% CI = 0.94 to 3.33; P = .076). Development of an arterial thromboembolic event was associated with a prior arterial thromboembolic event (P<.001) or age of 65 years or older (P = .01). Baseline or on-study aspirin use was associated with modest increases in grade 3 and 4 bleeding events in both treatment groups, from 3.6% to 4.7% for bevacizumab-treated patients and from 1.7% to 2.2% for control subjects. CONCLUSIONS: Combination treatment with bevacizumab and chemotherapy, compared with chemotherapy alone, was associated with an increased risk of arterial thromboembolism but not venous thromboembolism.

Combinatorial antiangiogenic gene therapy by nonviral gene transfer using the sleeping beauty transposon causes tumor regression and improves survival in mice bearing intracranial human glioblastoma.

Glioblastoma is a fatal brain tumor that becomes highly vascularized by secreting proangiogenic factors and depends on continued angiogenesis to increase in size. Consequently, a successful antiangiogenic therapy should provide long-term inhibition of tumor-induced angiogenesis, suggesting long-term gene transfer as a therapeutic strategy. In this study a soluble vascular endothelial growth factor receptor (sFlt-1) and an angiostatin-endostatin fusion gene (statin-AE) were codelivered to human glioblastoma xenografts by nonviral gene transfer using the Sleeping Beauty (SB) transposon. In subcutaneously implanted xenografts, co-injection of both transgenes showed marked anti-tumor activity as demonstrated by reduction of tumor vessel density, inhibition or abolition of glioma growth, and increase in animal survival (P = 0.003). Using luciferase-stable engrafted intracranial gliomas, the anti-tumor effect of convection-enhanced delivery of plasmid DNA into the tumor was assessed by luciferase in vivo imaging. Sustained tumor regression of intracranial gliomas was achieved only when statin-AE and sFlt-1 transposons were coadministered with SB-transposase-encoding DNA to facilitate long-term expression. We show that SB can be used to increase animal survival significantly (P = 0.008) by combinatorial antiangiogenic gene transfer in an intracranial glioma model.

Surgical wound healing complications in metastatic colorectal cancer patients treated with bevacizumab.

BACKGROUND: Bevacizumab (Avastin; rhuMab VEGF), a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), significantly prolongs survival when added to intravenous 5-fluorouracil-based chemotherapy in first-line metastatic colorectal cancer (CRC) treatment. Because antiangiogenic agents might inhibit wound healing, we assessed postoperative wound healing complications in two randomized trials of 5 mg/kg bevacizumab in CRC treatment. METHODS: We assessed the wound healing complications in patients who: (1) underwent cancer surgery 28-60 days before study treatment and (2) underwent major surgery during study treatment. Cases were reviewed for wound healing complications occurring < or = 60 days after surgery. RESULTS: With cancer surgery 28-60 days before study treatment, wound healing complications occurred in 3/230 (1.3%) bevacizumab-treated patients and 1/194 (0.5%) control patients. With major surgery during study treatment, 10/75 bevacizumab-treated patients (13%) and 1/29 control patients (3.4%) had wound healing complications. Bevacizumab-treated patients experienced complications with surgery < or = 30 and 31-60 days after the last dose. CONCLUSIONS: Bevacizumab administered in combination with 5-fluorouracil/leucovorin-based chemotherapy 28-60 days after primary cancer surgery caused no increased risk of wound healing complications compared with chemotherapy alone. While wound healing complications were increased in patients who had major surgery during bevacizumab therapy, the majority of bevacizumab-treated patients experienced no complications.

Phase II trial of the histone deacetylase inhibitor pivaloyloxymethyl butyrate (Pivanex, AN-9) in advanced non-small cell lung cancer.

This multicenter phase II trial evaluated the therapeutic activity and safety profile of pivaloyloxymethyl butyrate (Pivanex, AN-9) as a single agent in refractory non-small cell lung cancer (NSCLC). Pivanex (2.34 g/m2 per day) was administered as a 6-h continuous intravenous infusion, daily for 3 days, and repeated every 21 days until disease progression. Forty-seven patients were treated. More than 90% of patients had received both a platinum compound and a taxane and 32% had received three or more prior chemotherapy regimens. The most common toxicities were transient grade 1-2 fatigue (34%), nausea (17%), and dysgeusia (11%). Three patients had partial responses (6.4 and 95%; CI 1.4-18.7%) and 14 patients had stable disease for > or =12 weeks (30%). Median survival for all patients was 6.2 months with 1-year survival of 26%. For patients who received fewer than three prior chemotherapy regimens, median survival was 7.8 months and 1-year survival was 31%. Pivanex is well tolerated and appears to be active as a single agent in patients with advanced NSCLC refractory to previous chemotherapy. Based on its therapeutic activity and favorable safety profile, further studies of Pivanex in NSCLC, particularly in combination with current chemotherapeutic agents, are warranted.

The therapeutic potential of novel antiangiogenic therapies.

Promising new antiangiogenic strategies are emerging for the treatment of cancer. Numerous candidate drugs that target vascular endothelial growth factor, vascular endothelial growth factor receptors, integrins, matrix metalloproteinases and other blood vessel targets are being developed and tested in clinical trials. This review highlights the numerous drugs in clinical trials and expands on potential new approaches to inhibiting angiogenesis. These approaches include gene therapy, vaccine strategies and antiangiogenic radioligands. New insight has been gained from completed Phase III trials with antiangiogenic drugs and some of the major obstacles include design of trials, dosing, toxicities and resistance. This review will discuss these barriers and methods by which they can be overcome.

Mechanisms and future directions for angiogenesis-based cancer therapies.

Targeting angiogenesis represents a new strategy for the development of anticancer therapies. New targets derived from proliferating endothelial cells may be useful in developing anticancer drugs that prolong or stabilize the progression of tumors with minimal systemic toxicities. These drugs may also be used as novel imaging and radiommunotherapeutic agents in cancer therapy. In this review, the mechanisms and control of angiogenesis are discussed. Genetic and proteomic approaches to defining new potential targets on tumor vasculature are then summarized, followed by discussion of possible antiangiogenic treatments that may be derived from these targets and current clinical trials. Such strategies involve the use of endogenous antiangiogenic agents, chemotherapy, gene therapy, antiangiogenic radioligands, immunotherapy, and endothelial cell-based therapies. The potential biologic end points, toxicities, and resistance mechanisms to antiangiogenic agents must be considered as these therapies enter clinical trials.