Cetuximab monotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer

Successful management of infusion reaction accompanying the start of cetuximab therapy

INTRODUCTION

Cetuximab is a chimeric antibody registered for the therapy of advanced colorectal carcinoma after failure of standard chemotherapy. Rare infusion reactions that resulted in the cessation of therapy have been described after cetuximab administration.

CASE DESCRIPTION

We have observed severe infusion reactions accompanied by a loss of consciousness in two patients. The patients were transferred to intensive care unit, and the treatment was continued after administration of corticosteroids under careful monitoring of vital signs without any further serious reactions. In both cases, benefit of therapy with cetuximab could be demonstrated.

CONCLUSION

This experience indicates that cetuximab can be continued in patients who experience infusion reactions. Surveillance in the intensive care unit is mandatory during readministration of the drug.

A phase II trial of S-1 monotherapy in metastatic colorectal cancer after failure of irinotecan- and oxaliplatin-containing regimens

This is the first phase II study of S-1 monotherapy for patients with metastatic colorectal cancer after failure of both irinotecan- and oxaliplatin-containing regimens. The initial dose of S-1 was 35 mg m⁻², administered twice daily for 14 days every 3 weeks. Treatment was repeated until the occurrence of disease progression. Twenty-eight patients were enrolled. S-1 was administered to 21 patients as third-line therapy and to the remaining seven patients as fourth-line therapy. Of 26 evaluable patients, the overall response rate was 14.3% (95% CI, 0.4–28.1), and the disease control rate was 42.9% (95% CI, 23.3–62.4). With a median follow-up period of 227 days, median time to progression and overall survival duration were 91 and 414 days, respectively. The 1-year survival rate of all patients was 60.7%. There was no grade 4 toxicity. Grade 3 haematological toxicities were documented only in two patients. In conclusion, S-1 shows potential as a salvage regimen in heavily pretreated colorectal cancer patients. The twice-daily dose of 35 mg m⁻² was well tolerated and can be used in designing further combination chemotherapy.

Preclinical antitumor activity of BMS-599626, a pan-HER kinase inhibitor that inhibits HER1/HER2 homodimer and heterodimer signaling

PURPOSE

The studies described here are intended to characterize the ability of BMS-599626, a small-molecule inhibitor of the human epidermal growth factor receptor (HER) kinase family, to modulate signaling and growth of tumor cells that depend on HER1 and/or HER2.

EXPERIMENTAL DESIGN

The potency and selectivity of BMS-599626 were assessed in biochemical assays using recombinant protein kinases, as well as in cell proliferation assays using tumor cell lines with varying degrees of dependence on HER1 or HER2 signaling. Modulation of receptor signaling was determined in cell assays by Western blot analyses of receptor autophosphorylation and downstream signaling. The ability of BMS-599626 to inhibit receptor heterodimer signaling in tumor cells was studied by receptor coimmunoprecipitation. Antitumor activity of BMS-599626 was evaluated using a number of different xenograft models that represent a spectrum of human tumors with HER1 or HER2 overexpression.

RESULTS

BMS-599626 inhibited HER1 and HER2 with IC50 of 20 and 30 nmol/L, respectively, and was highly selective when tested against a broad panel of diverse protein kinases. Biochemical studies suggested that BMS-599626 inhibited HER1 and HER2 through distinct mechanisms. BMS-599626 abrogated HER1 and HER2 signaling and inhibited the proliferation of tumor cell lines that are dependent on these receptors, with IC50 in the range of 0.24 to 1 micromol/L. BMS-599626 was highly selective for tumor cells that depend on HER1/HER2 and had no effect on the proliferation of cell lines that do not express these receptors. In tumor cells that are capable of forming HER1/HER2 heterodimers, BMS-599626 inhibited heterodimerization and downstream signaling. BMS-599626 had antitumor activity in models that overexpress HER1 (GEO), as well as in models that have HER2 gene amplification (KPL4) or overexpression (Sal2), and there was good correlation between the inhibition of receptor signaling and antitumor activity.

CONCLUSIONS

BMS-599626 is a highly selective and potent inhibitor of HER1 and HER2 kinases and inhibits tumor cell proliferation through modulation of receptor signaling. BMS-599626 inhibits HER1/HER2 receptor heterodimerization and provides an additional mechanism of inhibiting tumors in which receptor coexpression and heterodimerization play a major role in driving tumor growth. The preclinical data support the advancement of BMS-599626 into clinical development for the treatment of cancer.

Multicenter randomized trial of adjuvant fluorouracil and folinic acid compared with surgery alone after resection of colorectal liver metastases: FFCD ACHBTH AURC 9002 trial

PURPOSE

Complete resection of liver metastases of colorectal origin is the only potentially curative treatment. In order to decrease recurrences, the use of adjuvant systemic chemotherapy after liver resection is controversial because no randomized study demonstrated its benefit.

PATIENTS AND METHODS

In a multicenter trial, we randomly assigned 173 patients with completely resected (R0) hepatic metastases from colorectal cancer to surgery alone and observation (87 patients) or to surgery followed by 6 months of systemic adjuvant chemotherapy with a fluorouracil and folinic acid monthly regimen (86 patients). The main outcome criterion was disease-free survival. Secondary outcome measures were overall survival and treatment-related toxicity.

RESULTS

The intention-to-treat analysis was based on 171 patients, after a median follow-up of 87 months (SE = 5.8). The 5-year disease-free survival rate, after adjustment for major prognostic factors, was 33.5% for patients in the chemotherapy group and 26.7% for patients in the control group (Cox multivariate analysis: odds ratio for recurrence or death = 0.66; 95% CI, 0.46 to 0.96; P = .028). With regard to secondary outcome measures, a trend towards increased overall survival was observed but did not reach statistical significance (5-year overall survival: chemotherapy group, 51.1% v control group, 41.1%; odds ratio for death, 0.73; 95% CI, 0.48 to 1.10; P = .13).

CONCLUSION

Despite a suboptimal regimen, which was the standard at the beginning of the study, adjuvant intravenous systemic chemotherapy provided a significant disease-free survival benefit for patients with resected liver metastases from colorectal cancer.

Small molecule tyrosine kinase inhibitors in the treatment of solid tumors: an update of recent developments

Small molecule tyrosine kinase inhibitors (TKIs) are developed to block intracellular signaling pathways in tumor cells, leading to deregulation of key cell functions such as proliferation and differentiation. Over 25 years ago, tyrosine kinases were found to function as oncogenes in animal carcinogenesis; however, only recently TKIs were introduced as anti cancer drugs in human cancer treatment. Tyrosine kinase inhibitors have numerous good qualities. First, in many tumor types they tend to stabilize tumor progression and may create a chronic disease state which is no longer immediately life threatening. Second, side effects are minimal when compared to conventional chemotherapeutic agents. Third, synergistic effects are seen in vitro when TKIs are combined with radiotherapy and/or conventional chemotherapeutic agents. In this article, we will give an update of the tyrosine kinase inhibitors that are currently registered for use or in an advanced stage of development, and we will discuss the future role of TKIs in the treatment of solid tumors. The following TKIs are reviewed: Imatinib (Gleevec/Glivec), Gefitinib (Iressa), Erlotinib (OSI-774, Tarceva), Lapatinib (GW-572016, Tykerb), Canertinib (CI-1033), Sunitinib (SU 11248, Sutent), Zactima (ZD6474), Vatalanib (PTK787/ZK 222584), Sorafenib (Bay 43-9006, Nexavar), and Leflunomide (SU101, Arava).

Molecular determinants of irinotecan efficacy

Molecular markers predicting the efficacy of CPT-11 based chemotherapies in patients with colorectal cancer (CRC) are unknown. Therefore, we investigated whether mRNA levels of drug targets (Topoisomerase I, TS), enzymes involved in 5-FU metabolism (DPD), in angiogenesis (EGFR, IL-8, VEGF) and in DNA-repair/drug detoxification (ERCC1, GST-P1) are associated with the clinical outcome of patients with CRC treated with first-line CPT-11 based chemotherapy. Thirty three patients with metastatic CRC were included in the study. Intratumoral gene expression levels were assessed from paraffin-embedded tissue samples, using laser capture microdissection and quantitative Real-Time PCR. Complete response was observed in 1 patient, partial response in 12 patients, stable disease in 13 patients and progressive disease in 6 patients. Response was inevaluable for 1 patient. Patients with complete response or partial response were classified as responders, while patients with stable disease or progressive disease were classified as nonresponders. High intratumoral mRNA levels of EGFR, ERCC1 and GSPT-P1 were each significantly associated with response to CPT-11 based chemotherapy. Recursive partitioning analysis showed that mRNA levels of EGFR and ERCC1 are primarily responsible for delineating responders from nonresponders. Also, the combination of high intratumoral gene expression levels of both EGFR and ERCC1 was significantly associated with progression-free survival. The mRNA levels of EGFR had a significant correlation with expression levels of ERCC1, GST-P1 and VEGF. This small retrospective study suggests that gene expression levels of EGFR, ERCC1 and GST-P1 may be useful in predicting the clinical outcome of patients with metastatic CRC treated with first-line CPT-11 based chemotherapy.

Multicenter phase II and translational study of cetuximab in metastatic colorectal carcinoma refractory to irinotecan, oxaliplatin, and fluoropyrimidines

PURPOSE

This multicenter study evaluated the antitumor activity of cetuximab, an immunoglobulin G1 antibody directed at the epidermal growth factor receptor (EGFR), in metastatic colorectal carcinoma (CRC) refractory to irinotecan, oxaliplatin, and a fluoropyrimidine. It also evaluated the safety, pharmacokinetics, immunokinetics, and biologic determinants of activity.

PATIENTS AND METHODS

Patients with metastatic CRC, whose tumors demonstrated EGFR immunostaining and were refractory to irinotecan, oxaliplatin, and fluoropyrimidines, were treated with cetuximab at a loading dose of 400 mg/m2 followed by 250 mg/m2 weekly. An independent review committee (IRC) reviewed responses. Blood was collected for cetuximab pharmacokinetics and to detect antibodies to cetuximab. EGFR gene sequencing of the tyrosine kinase domain and gene copy number assessments were performed.

RESULTS

The response rates in 346 patients, as determined by the investigators and IRC, were 12.4% (95% CI, 9.1 to 16.4) and 11.6% (95% CI, 8.4 to 16.4). The median progression-free survival (PFS) and survival times were 1.4 months (95% CI, 1.4 to 2.1) and 6.6 months (95% CI, 5.6 to 7.6), respectively. An acneiform rash occurred in 82.9% of patients; grade 3 rash was observed in 4.9%. Response and survival related strongly to the severity of the rash. In contrast, clinical benefit did not relate to EGFR immunostaining. EGFR tyrosine kinase domain mutations were not identified, and EGFR gene copy number did not relate to response or PFS, but to survival (P = .03).

CONCLUSION

Cetuximab is active and well tolerated in metastatic CRC refractory to irinotecan, oxaliplatin, and fluoropyrimidines. The severity of rash was related to efficacy. Neither EGFR kinase domain mutations nor EGFR gene amplification appear to be essential for response to cetuximab in this setting.

Phase II trial of erlotinib in gastroesophageal junction and gastric adenocarcinomas: SWOG 0127

PURPOSE

A phase II trial of the oral epidermal growth factor receptor (EGFR) inhibitor erlotinib in patients with gastroesophageal adenocarcinomas stratified according to primary tumor location into two groups: gastroesophageal junction (GEJ)/cardia and distal gastric adenocarcinomas.

PATIENTS AND METHODS

Patients with a histologically proven diagnosis of adenocarcinoma of the GEJ or stomach (ST) that was unresectable or metastatic; presence of measurable disease; no prior chemotherapy for advanced or metastatic cancer; Zubrod performance status (PS) of 0 to 1; and adequate renal, hepatic, and hematologic function were treated with erlotinib 150 mg/d orally. Patient characteristics were median age, GEJ-63 years, ST-64 years; sex, GEJ-84% male and 16% female, ST-60 male and 40 female; Zubrod PS, GEJ-25 had a PS of 0 and 18 had a PS 1, ST-13 had a PS of 0 and 12 had a PS of 1.

RESULTS

Percentage of common toxicities were skin rash, 86% and 72%; fatigue, 51% and 44%; and AST/ALT elevation, 28% and 28%, respectively for GEJ and ST. There has been one confirmed complete response, three confirmed partial responses (PRs) and one unconfirmed PR for an overall response probability of 9% confirmed (95% CI, 3% to 22%), all occurring in GEJ stratum. No responses were observed in ST stratum. The median survival was 6.7 months in GEJ and 3.5 months in ST stratum. Neither intratumoral EGFR, transforming growth factor-alpha or phosphorylated Akt kinase expression nor plasma proteomic analyses were predictive of clinical outcome. No somatic mutations of the EGFR exons 18, 19, or 21 were detected and there was no gross amplification of EGFR by fluorescence in situ hybridization.

CONCLUSION

Erlotinib is active in patients with GEJ adenocarcinomas, but appears inactive in gastric cancers. The molecular correlates examined were not predictive of the patient therapeutic response.

EGFR-targeted immunoliposomes derived from the monoclonal antibody EMD72000 mediate specific and efficient drug delivery to a variety of colorectal cancer cells

We hypothesized that immunoliposomes (ILs) constructed using Fab' from the humanized anti-EGFR monoclonal antibody, EMD72000, can provide efficient intracellular drug delivery in EGFR-overexpressing colorectal tumor cells.ILs were constructed modularly with various MAb fragments, including Fab' from EMD72000 (matuzumab) or C225 (cetuximab, Erbitux) covalently linked to stabilized liposomes containing chemotherapeutic drugs or probes. Immunoliposome preparation was optimized, including Fab' reduction and linkage, and evaluated for specific binding and cytotoxicity in epidermal growth factor receptor (EGFR)--overexpressing colorectal cancer cell lines in vitro. Flow cytometry showed that EGFR-targeted ILs, but not non-targeted liposomes or irrelevant ILs, were efficiently bound and internalized by a variety of EGFR-overexpressing colorectal cancer cells. Linkage of the Fab' to a longer PEG chain (Mal-PEG3400-DSPE) resulted in an increased uptake of immunoliposomal constructs when compared to previously used materials (Mal-PEG2000-DSPE). ILs derived from EMD72000-Fab' were used to deliver doxorubicin to EGFR-overexpressing target cells in vitro. Immunoliposomal doxorubicin was significantly more cytotoxic than the corresponding non-targeted liposomal drug in target cells, such as HCT116, while equivalent in cells lacking EGFR-overexpression, such as Colo205. We conclude that EGFR-targeted ILs derived from the humanized MAb EMD72000 provide efficient and targeted delivery of anticancer drugs in colorectal cancer cells overexpressing EGFR.

Does the EGFR and VEGF expression predict the prognosis in colon cancer?

BACKGROUND/AIM

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) are frequently encountered with aggressive tumor phenotype and poor prognosis, but the relationship between EGFR/VEGF expression and survival remains unclear. The aim of our study was to further investigate the prognostic value of EGFR and VEGF expression in colon cancer.

MATERIALS AND METHODS

The pathological specimens of 60 colon carcinoma patients were retrospectively evaluated and grouped according to EGFR and VEGF staining intensity and percentage of stained neoplastic cells. A final score was assigned to each case by multiplying percentage and staining score. The patients were stratified into the following categories: negative (score 0), low expression (score 1 or 2), and high expression (score 4). The remaining patient data were filtered out from the institutional cancer database.

RESULTS

The mean survival time was 28.93 +/- 14.1 (range 2-52) months in the EGFR-negative group, 23.92 +/- 14.0 (range 6-46) months in the group with a low EGFR expression, and 17.00 +/- 12.8 (range 10-40) months in the group with a high EGFR expression. The median survival time was 27.50 +/- 14.7 (range 4-52) months in the VEGF-negative group, 29.33 +/- 12.8 (range 6-48) months in the group with a low VGEF expression, and 14.50 +/- 14.2 (range 2-40) months in the group with a high VGEF expression. The expression of EGFR and VEGF was not an independent factor that affects survival.

CONCLUSIONS

The EGFR and VEGF expression rates of colon tumors do not predict the survival. In addition, the EGFR expression in the primary tumor was not predictive of metastatic lymph nodes. The prognostic value of EGFR/VEGF staining may be further questioned.

Clinical Trials in a Molecular World

New therapies aimed at molecular abnormalities are often more efficacious and less toxic than nontargeted therapies; however, with current technology, major treatment decisions are being made with inadequate data. This problem needs to be fixed by molecular imaging technology, enabling he noninvasive establishment of the presence of a molecular target, its spatial distribution and heterogeneity, and how this changes over time. This article discusses the status of molecular imaging in clinical trails today, and looks forward to what physicians would like it to become.

Phase II trial of capecitabine and oxaliplatin (CAPOX) plus cetuximab in patients with metastatic colorectal cancer who progressed after oxaliplatin-based chemotherapy

BACKGROUND

Cetuximab is an IgG1 monoclonal antibody targeting the epidermal growth factor receptor and is able to reverse the resistance to irinotecan in patients with metastatic colorectal cancer (mCRC). This phase II trial evaluates the safety and efficacy of cetuximab combined with capecitabine and oxaliplatin (CAPOX) in the treatment of patients with mCRC progressing under oxaliplatin-based chemotherapy.

PATIENTS AND TREATMENT

Forty patients with mCRC were treated with cetuximab (loading dose 400 mg/m(2) and then 250 mg/m(2) i.v. weekly) in combination with CAPOX (d(1): L-OHP 85 mg/m(2) and d(1-7) capecitabine 2000 mg/m(2) every 2 weeks). Thirty-one (77.5%) and nine (22.5%) patients had oxaliplatin-refractory and -resistant disease, respectively; in addition, 32 (80%) patients had also progressed on prior irinotecan-based chemotherapy.

RESULTS

One hundred and thirty-four cycles were administered (median of four cycles per patient). Main toxic effects included grade 3-4 neutropenia (12.5%), grade 3/4 diarrhea (7.5%), grade 3 fatigue (2.5%), and grade 2-3 neurotoxicity (22.5%). One (2.5%) complete and seven (17.5%) partial responses were achieved [overall objective response rate (ORR): 20%; 95% confidence interval (CI): 9% to 32%)], whereas 11 (27.5%) patients had stable disease [disease control rate (DCR): 47.5%; 95% CI: 30.2% to 64.5%]. The ORR and DCR were 18.7% and 46.8%, respectively, in patients with oxaliplatin-refractory disease. The median time to tumor progression was 3 months, the median survival 10.7 months and the probability of 1-year survival rate 53.4%.

CONCLUSIONS

The combination of cetuximab plus CAPOX is safe and has a promising activity in patients with mCRC refractory or resistant to oxaliplatin.

Skin rash secondary to bevacizumab in a patient with advanced colorectal cancer and relation to response

Bevacizumab (Avastin) in combination with intravenous 5-fluorouracil-based chemotherapy as first-line as well as second-line treatment of metastatic colorectal cancer improves survival. Although skin rash (type unspecified) has been described in some patients following infusion of bevacizumab, it is not a common toxicity of bevacizumab, while acneiform rash occurs in more than 90% of patients who receive cetuximab (Erbitux), the severity of which appears to be predictive of response. We report a patient with colorectal cancer who developed a rash secondary to bevacizumab that correlated with response. A 40-year-old patient with stage IV colorectal cancer received FOLFOX-4 and bevacizumab, which he tolerated very well except for a skin rash related to bevacizumab. The rash cleared every time bevacizumab was eliminated from the chemotherapy regimen. When use of bevacizumab was resumed, similar rash reappeared. Therefore, we believe that this observation of the rash emergence was linked to bevacizumab administration. The most common toxicities associated with bevacizumab include hypertension, hemorrhage, gastrointestinal perforation, arterial thromboembolism, wound healing and proteinuria. Exfoliative dermatitis and a nonspecific rash have been reported with bevacizumab. This case report, we believe, is the first report of a possible correlation between a rash and a positive drug response associated with bevacizumab, and may initiate further investigation of similar observation.

Molecular determination of epidermal growth factor receptor in normal and neoplastic colorectal mucosa

The epidermal growth factor receptor (EGFr) is considered a major target for treatment of colorectal cancer (CRC). We found a mean EGFr content significantly lower but more activated in colonic neoplastic tissue than in paired normal mucosa. Phosphorylated (pY1068) EGFr detection in CRC may be a better tool than EGFr detection to select patients for targeted therapies.

The new era in the treatment of advanced colorectal cancer patients: the role of monoclonal antibodies

Colorectal cancer (CRC) represents a major health problem in the Western world. Approximately 60% of patients with CRC require systemic therapy for metastatic disease, either at diagnosis or at disease recurrence. Until recently, classic chemotherapeutic agents have been combined in the treatment of advanced CRC. The recent considerable development of novel monoclonal antibodies that target key components of biological pathways has expanded the options to treat advanced CRC patients. These newer agents more specifically target unique features of the cancer cell and its surroundings and so attempt to exploit the progress that has been made in the understanding of basic cell biology. Two targets in particular--the process of new blood vessel development, or angiogenesis, and the EGF receptor and its signalling pathway--are exploited by the newest monoclonal antibodies available for use in this setting. This clinical review focuses on the defining role of the two most clinically advanced novel agents, bevacizumab and cetuximab in metastatic colorectal cancer.

Pharmacokinetics of Cetuximab After Administration of Escalating Single Dosing and Weekly Fixed Dosing in Patients with Solid Tumors

PURPOSE

Previous studies of cetuximab pharmacokinetics did not fully characterize its elimination phase. The purpose of this trial was to evaluate the pharmacokinetics of cetuximab given as a single dose followed by weekly fixed repeated dosing in patients with solid tumors.

EXPERIMENTAL DESIGN

Patients were randomly assigned to treatment with a single 2-hour infusion of cetuximab at doses of 50, 100, 250, 400, or 500 mg/m2 followed 3 weeks later by weekly 1-hour infusions of cetuximab at a fixed dose of 250 mg/m2. Extended pharmacokinetic sampling was collected through 504 hours after the first drug administration. Trough samples were obtained before each fixed weekly dose. Single and multidose pharmacokinetic variables were correlated with clinical outcomes.

RESULTS

Forty patients were enrolled. Pharmacokinetic analysis confirmed previous reports of nonlinear pharmacokinetics for cetuximab. Modeling studies predicted a 90% saturation of clearance at a dose of 260 mg/m2. Analyses of weekly trough concentrations indicated a slight accumulation of drug concentrations following repeated weekly dosing. Correlative studies indicated a significant association between cetuximab clearance and both body surface area (P=0.002) and weight (P=0.002). The occurrence of rash was significantly associated with disease stability (P<0.002) but not with cetuximab pharmacokinetic variables.

CONCLUSIONS

Pharmacokinetic results support using body surface area or weight in calculating individual cetuximab doses. A weekly dose of 250 mg/m2 is predicted to nearly fully saturate cetuximab clearance and, by inference, epidermal growth factor receptors. The association between rash and disease stability supports further prospective studies of this relationship.

Epidermal growth factor receptor inhibition and non-small cell lung cancer

The majority of non-small cell (NSC) lung cancers express epidermal growth factor receptor (EGFR). Many studies have evaluated the clinical effect from targeted therapy achieved by blocking EGFR in patients with NSC lung cancer. Treatment of biologically unselected patients with NSC lung cancer with two reversible quinazole EGFR inhibitors, gefitinib and erlotinib, gave negative results in all controlled trials but one. Ten percent to 20% of patients with NSC lung cancers have somatic mutations in EGFR, and these patients have a significantly higher response rate (73%) to treatment with EGFR inhibitors than patients with wild-type EGFR (10%). Patients with Asian background, women, non-smokers, and patients with adenocarcinoma had higher response rates than other patients, and the differences may be due to an association between the clinical characteristics and EGFR mutations. Further studies are needed to fully evaluate the effect of EGFR inhibitor-treatment for subgroups of patients with NSC lung cancer with favorable biological and clinical characteristics.

Pancreatic cancer: a review of recent advances

Pancreatic cancer is one of the most common causes of cancer-related death. Despite the advances of the molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. Overall, the 5-year survival rate is < 5% and only approximately 20% of the 10% of patients with resectable disease survive 5 years. Recently, the European Study Group for Pancreatic Cancer 1 trial demonstrated substantially increased survival from adjuvant chemotherapy with 5-fluorouracil-folinic acid and preliminary data showed prolonged disease-free survival from adjuvant gemcitabine. Current palliative therapeutic approaches mostly focused on evaluating chemotherapy regimens in which gemcitabine is combined with a second cytotoxic agent. Recently, large randomised trials of combinations of gemcitabine with either capecitabine or with erlotinib demonstrated prolonged survival and 1-year survival rates of approximately 25%. The advance of molecular biology has led to the elucidation of molecular events that are important for pancreatic carcinogenesis and has provided a foundation for the development of novel chemotherapeutic and biological agents that appear to be promising and are likely to play a future role in the treatment of patients with advanced pancreatic cancer.

Clinical implications of the mechanism of epidermal growth factor receptor inhibitors

Novel therapeutic agents that target the epidermal growth factor receptor (EGFR) constitute an important addition to the therapeutic armamentarium for the treatment of metastatic disease. EGFR-targeted agents currently approved by the U.S. Food and Drug Administration include cetuximab, a monoclonal antibody for the treatment of colorectal cancer; and the small-molecule EGFR tyrosine kinase inhibitor (TKI) erlotinib for the treatment of nonsmall cell lung cancer (NSCLC) and pancreatic cancer. Approval of the TKI gefitinib for NSCLC recently was withdrawn. Although both classes of anti-EGFR agents target the same receptor, substantial distinctions regarding their mechanism significantly affect dosing requirements, toxicity profiles, and their use as combination agents.

Panitumumab in colon cancer: a review and summary of ongoing trials

Panitumumab is a fully human antibody developed against the human epidermal growth factor receptor receptor (EGFR/HER-1), which is overexpressed in > or = 75% of patients with colorectal cancer. As a fully human antibody, panitumumab can be administered without any premedication and has the promise of decreased infusion reactions. Clinical studies have demonstrated that panitumumab has significant activity as a single agent and improves progression-free survival when compared with best supportive care. It can also be safely combined with standard cytotoxic chemotherapy. Ongoing studies are being performed to determine if the addition of panitumumab to first-line standard treatment for metastatic colorectal cancer will improve the progression-free and overall survival of these patients.

The role of companion diagnostics in the development and use of mutation-targeted cancer therapies

Among all the known differences between cancer and normal cells, it is only the genetic differences that unequivocally distinguish the former from the latter. It is therefore not surprising that recent therapeutic advances are based on agents that specifically target the products of the genes that are mutated in cancer cells. The ability to identify the patients most likely to benefit from such therapies is a natural outgrowth of these discoveries. Development of companion diagnostic tests for this identification is proceeding but should receive much more attention than it currently does. These tests can simplify the drug discovery process, make clinical trials more efficient and informative, and be used to individualize the therapy of cancer patients.

Sequence-dependent inhibition of human colon cancer cell growth and of prosurvival pathways by oxaliplatin in combination with ZD6474 (Zactima), an inhibitor of VEGFR and EGFR tyrosine kinases

To date, clinical studies combining the new generation of targeted therapies and chemotherapy have had mixed results. Preclinical studies can be used to identify potential antagonism/synergy between certain agents, with the potential to predict the most efficacious combinations for further investigation in the clinical setting. In this study, we investigated the sequence-dependent interactions of ZD6474 with oxaliplatin in two human colon cell lines in vitro. We evaluated the in vitro antitumor activity of ZD6474, an inhibitor of vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR) and RET tyrosine kinase activity, and oxaliplatin using three combination schedules: ZD6474 before oxaliplatin, oxaliplatin before ZD6474, and concurrent exposure. Cell proliferation studies showed that treatment with oxaliplatin followed by ZD6474 was highly synergistic, whereas the reverse sequence was clearly antagonistic as was concurrent exposure. Oxaliplatin induced a G(2)-M arrest, which was antagonized if the cells were previously or concurrently treated with ZD6474. ZD6474 enhanced oxaliplatin-induced apoptosis but only when added after oxaliplatin. The sequence-dependent antitumor effects appeared, in part, to be based on modulation of compensatory prosurvival pathways. Thus, expression of total and active phosphorylated EGFR, as well as AKT and extracellular signal-regulated kinase, was markedly increased by oxaliplatin. This increase was blocked by subsequent treatment with ZD6474. Furthermore, the synergistic sequence resulted in reduced expression of insulin-like growth factor-I receptor and a marked reduction in secretion of vascular endothelial growth factor protein. ZD6474 in combination with oxaliplatin has synergistic antiproliferative properties in human colorectal cancer cell lines in vitro when oxaliplatin is administered before ZD6474.

Targeted therapy in advanced non-small cell lung cancer (NSCLC): where do we stand?

Cytotoxic chemotherapy has helped improve the outcomes in patients with advanced non-small cell lung cancer (NSCLC), but we seem to have reached a plateau with respect to the benefit obtained. Also, a large subset of elderly patients and those with a poor performance status cannot tolerate these drugs at recommended doses. There is a growing need to incorporate newer drugs with different mechanisms of action and better safety profile. The epidermal growth factor receptor family (EGFR) and vascular endothelial growth factor (VEGF) have been identified as potential targets and agents acting specifically against these targets have been developed with the hope of improving outcomes. Although recent data with the small molecule EGFR tyrosine kinase inhibitors have been disappointing, there have been instances of dramatic responses thereby raising questions about the ideal patient to whom these drugs should be administered. Cetuximab, the anti-EGFR antibody has shown promising results. Bevacizumab, the anti-VEGF antibody was the first drug to demonstrate a survival benefit in first line treatment when added to chemotherapy. This review will briefly discuss the important trials using these targeted agents in advanced NSCLC.

Bevacizumab in the treatment of colorectal cancer

Bevacizumab is a humanised monoclonal antibody that inhibits vascular endothelial growth factor (VEGF), the key mediator of tumour angiogenesis, and has been shown to improve survival when given with chemotherapy to patients with metastatic colorectal cancer. In a pivotal Phase III clinical trial, 813 subjects were treated with irinotecan, 5-fluorouracil (5-FU) and leucovorin and randomised to receive placebo or bevacizumab. Median survival for the group receiving bevacizumab was increased by 30%, from 15.6 to 20.3 months (p < or = 001). Other Phase II and III studies in colorectal cancer have demonstrated a benefit when bevacizumab is added to regimens of 5-FU and leucovorin, and 5-FU, leucovorin and oxaliplatin. The toxicity associated with bevacizumab is generally mild, consisting of manageable hypertension, clinically insignificant proteinuria and mild mucosal bleeding. Infrequent severe toxicities have been reported, consisting of arterial thrombosis and gastrointestinal perforations (1.5%). Bevacizumab represents the first angiogenesis modulator that has a proven benefit in cancer therapy.

Dermatologic side effects associated with the epidermal growth factor receptor inhibitors

Epidermal growth factor receptor (EGFR) inhibitors are associated with unique and dramatic dermatologic side effects. Cetuximab, erlotinib, and gefitinib have been approved for patients with colorectal and non-small cell lung cancer refractory or intolerant to chemotherapy. Our aim was to describe key clinical features of common dermatologic adverse reactions among EGFR inhibitors, focusing mainly on skin toxicity, as well as to discuss the pathology, possible causes, and suggested treatments for these reactions. The most commonly encountered adverse effect was a mild skin toxicity characterized by a sterile follicular and pustular rash that may be treated empirically and usually does not require treatment modification. Although the precise mechanism for development of rash is not well defined, it is related to inhibition of EGFR-signaling pathways in the skin, and may serve as visible markers of anti-tumor activity and therapeutic efficacy. Secondary adverse reactions seen with anti-EGFR therapy include xerosis, pruritus, paronychia, hair abnormality, and mucositis.

Prediction of response to chemoradiation in rectal cancer by a gene polymorphism in the epidermal growth factor receptor promoter region

PURPOSE

Epidermal growth factor receptor (EGFR) has been associated with radioresistance in solid tumors. Recently a polymorphism in the Sp1 recognition site of the EGFR promoter region was identified. The present study investigated the predictive value of this polymorphism for the outcome of chemoradiation in locally advanced rectal cancer.

METHODS AND MATERIALS

The study included 77 patients with locally advanced T3 rectal tumors. Treatment consisted of preoperative radiation therapy at a total tumor dose of 65 Gy and concomitant chemotherapy with Uftoral. Blood samples from 63 patients were evaluated for Sp1 -216 G/T polymorphism by polymerase chain reaction analysis. Forty-eight primary tumor biopsies were available for EGFR immunostaining. Patients underwent surgery 8 weeks after treatment. Pathologic response evaluation was performed according to the tumor regression grade (TRG) system.

RESULTS

Forty-nine percent had major response (TRG1-2) and 51% moderate response (TRG 3-4) to chemoradiation. The rates of major response were 34% (10/29) in GG homozygote patients compared with 65% (22/34) in patients with T containing variants (p=0.023). Fifty-eight percent of biopsies were positive for EGFR expression (28/48). The major response rates with regard to EGFR immunostaining were not significantly different. EGFR-positive tumors were found in 83% of the GG homozygote patients compared with 38% of patients with TT or GT variants (p=0.008).

CONCLUSIONS

There was a significant correlation between EGFR Sp1 -216 G/T polymorphism and treatment response to chemoradiation in locally advanced rectal cancer. Further investigations of a second set of patient and other treatment schedules are warranted.

Metastatic colorectal cancer: Therapeutic options

For the past several decades, the therapy for metastatic colorectal cancer had modest benefits because of the limited therapeutic options. Bolus 5-fluorouracil (5FU) and leucovorin (LV) were the standard of care in the United States until 2002, with a response rate of 25% and a median survival of 10 to 12 months. However, with the advent of new agents, namely oxaliplatin and irinotecan, there has been a dramatic change in the way we treat metastatic colorectal cancer. Based on many well-conducted large randomized trials, we have evidence that combination chemotherapy incorporating oxaliplatin or irinotecan with infusional 5FU/LV is superior to 5FU/LV, with doubling of overall survival (OS) to approximately 20 months. There remains some uncertainty as to the best first-line regimen. This might be irrelevant because studies have shown that OS is dependent on exposure to all the active agents, regardless of the time period of exposure. Bevacizumab, which uses anti-angiogenic strategies, has improved disease-free survival (DFS) and OS when combined with standard chemotherapy and is a vital component of metastatic colorectal cancer therapy. However, there are no data supporting its use past progression. Cetuximab, an epithelial growth factor receptor inhibitor, is mainly used in irinotecan-refractory patients. In spite of all these advances, 5-year OS rates continue to be limited. Patients with curative resection of metastatic disease seem to have longer DFS and better 5-year OS rates. This should be a potential goal for responding patients with upfront unresectable, organ-limited disease.

Recent advances in the systemic management of colorectal cancer

Colorectal cancer represents one of the most prevalent malignancies. There have been considerable improvements in the management of the disease in the last decade, including advances in surgery. In terms of systemic management, 5-fluorouracil, usually with leucovorin, has remained the mainstay of chemotherapy for colorectal cancer in both the adjuvant and metastatic settings. In the late 1990s, irinotecan and oxaliplatin reached the clinical arena, and the introduction of these agents has led to significant improvements in outcomes. More recently, several biopharmaceuticals, including the monoclonal antibodies bevacuzimab and cetuximab, have shown promise in clinical studies. These novel agents are now being incorporated into treatment schedules for colorectal cancer. This review assesses recent improvements in the systemic management of large bowel cancer and highlights future challenges.

Challenges in the Use of Epidermal Growth Factor Receptor Inhibitors in Colorectal Cancer

Novel targeted agents increase the therapeutic armamentarium in metastatic colorectal cancer (mCRC). Monoclonal antibodies against the epidermal growth factor receptor (EGFR) are active against EGFR-expressing mCRC that is refractory to irinotecan. EGFR monoclonal antibodies also have promise in less advanced stages of CRC. Cetuximab and panitumumab are clearly active agents. It has been shown that cetuximab is more active when administered in combination with irinotecan. Phase II studies also report promising activity when monoclonal antibodies against the EGFR are combined with classic chemotherapeutic regimens in the first-line treatment of mCRC. However, the best means of scheduling such agents and integrating them with each other and with chemotherapy have yet to be established. The management of toxicity (particularly rash) and finding appropriate means of selecting patients pose additional challenges. While the occurrence of rash is associated with greater likelihood of response, EGFR staining by immunohistochemistry at baseline is not. For reasons that are not yet clear, the tyrosine kinase inhibitors of EGFR seem less effective than their monoclonal antibody counterparts in the therapy of mCRC.

Therapy for Metastatic Colorectal Cancer

Median overall survival of metastatic colorectal cancer patients treated with first- and second-line combination chemotherapy now extends to more than 20 months in some studies. Chemotherapy alone, particularly when oxaliplatin is included, may allow potentially curative resection of advanced disease. There is evidence that the addition of antibodies targeted against vascular endothelial growth factor or the epidermal growth factor receptor will further improve prospects for patients with advanced and metastatic disease. However, the optimum sequencing of chemo- and biological therapies remains to be established, as does the potential contribution of numerous agents in development.

Outcome of metastatic colorectal cancer: analysis of a consecutive series of 229 patients. The impact of a multidisciplinary approach

PURPOSE

New chemotherapy agents and integrated treatments have improved the prognosis of patients with metastatic colorectal cancer.

METHODS

From January 2000 to December 2002, 229 consecutive metastatic patients were prospectively followed and their outcomes were analyzed. They were divided initially into four treatment groups: A, palliative chemotherapy for extensive extrahepatic disease with or without hepatic disease (97 patients); B, palliative chemotherapy as in Group A for extensive hepatic disease unlikely to become resectable (36 patients); C, neoadjuvant chemotherapy for potentially resectable liver metastases if responsive to therapy (33 patients); D, immediate surgery for liver metastases (63 patients).

RESULTS

The series was analyzed after a median follow-up of 22.6 months. The median progression-free survival was 9, 7.3, 11.5, and 26 months in Groups A, B, C, and D, respectively. The median overall survival was 20.1, 17.2, 24.8, and >48 months in Groups A, B, C, and D, respectively. The outcome was considered for the 69 patients with metastases confined to the liver (Groups B and C), who were treated initially with chemotherapy. Surgery was performed in 21 patients (5 from Group B, and 16 from Group C) and was R0 in 16. In resected patients, the median progression-free survival was 14.7 months and the median overall survival was 40.5 months. In unresected patients, the median progression-free survival was 7.6 months and the median overall survival was 17.5 months.

CONCLUSIONS

Neoadjuvant therapy may prolong overall survival in a subset of patients with multiple hepatic metastases. The global impact on progression-free survival is low; less than one-half of the patients resected after chemotherapy are disease-free at three years. However, patients resected after chemotherapy obtained overall survival similar to that of primary surgery, suggesting a positive role for integrated approaches.

Cetuximab-induced hypomagnesemia in patients with colorectal cancer

BACKGROUND

Cetuximab treatment has been associated with severe hypomagnesemia, but the predisposing factors and management of this toxicity have been poorly characterized.

PATIENTS AND METHODS

The charts of 114 patients with colorectal cancer treated with cetuximab were reviewed. Forty-eight evaluable patients had normal magnesium levels before initiation of cetuximab and >or=1 repeat magnesium level during cetuximab treatment. The incidence, grade, and management of hypomagnesemia were described in the evaluable population.

RESULTS

Among the evaluable population, 13 patients developed grade 3/4 hypomagnesemia (27%). The incidence of grade 3/4 hypomagnesemia was 6%, 23%, and 47% in patients receiving < 3 months, 3-6 months, and > 6 months of cetuximab therapy, respectively. Grade 3/4 hypomagnesemia was refractory to oral supplementation and required daily to 3-times-weekly intravenous magnesium sulfate supplementation at 6-10 g per dose. Recovery or amelioration in hypomagnesemia occurred approximately 4 weeks after cetuximab discontinuation.

CONCLUSION

Severe hypomagnesemia is a frequent side effect of cetuximab therapy. Treatment of hypomagnesemia requires frequent intravenous magnesium supplementation and can be associated with significant patient inconvenience and an increased risk of venous access-related complications. Intermittent cetuximab schedules need to be investigated in order to reduce the frequency and severity of hypomagnesemia.

Isolation and characterization of circulating tumor cells in patients with metastatic colorectal cancer

PURPOSE

Development of targeted therapeutic agents in colorectal cancer (CRC) is impeded by the lack of a noninvasive surrogate of drug effect. This pilot study evaluated the ability of immunomagnetic separation to isolate circulating tumor cells (CTCs) and of the fluorescent microscope system and flow cytometry to enumerate and characterize CTCs from patients with metastatic CRC.

PATIENTS AND METHODS

Fifty patients with metastatic CRC contributed 50 mL of blood at treatment initiation and disease evaluation timepoints. Fresh tumor specimens were obtained from 17 patients for comparison of circulating and in situ tumor cell characteristics. Epithelial cells were magnetically isolated from whole blood targeting the antiepithelial cell adhesion molecule (EpCAM). Circulating tumor cells were defined as EpCAM isolated, cytokeratin positive, nuclear stain positive, and CD45 negative. Total RNA was isolated from EpCAM-enriched CTCs and multigene reverse-transcriptase polymerase chain reaction analyses were performed.

RESULTS

The median number of CTCs detected by flow cytometry was 2/7.5 mL blood. Mean change in cell count was significantly different for patients with tumor progression versus nonprogression (+6.7 vs. +0.2/7.5 mL; P = 0.001). A correlation was noted between mean fluorescence intensity (flow cytometry) of cytokeratin in CTC and matched tumor specimens (r = 0.79, P = 0.06). Nearly 80% (15 of 19) of samples with >or= 2 CTCs expressed >or= 1 epithelial marker gene (CK19, CK20, carcinoembryonic antigen, or epidermal growth factor receptor).

CONCLUSION

Isolating and characterizing CTCs from patients with metastatic CRC is feasible. Change in the CTC number might reflect clinical status, and flow cytometric and gene expression data suggest similarity of circulating and in situ tumor cells. Further evaluation of CTCs for pharmacodynamic and clinical monitoring in patients with CRC is warranted.

Responses of human colorectal tumor cells to treatment with the anti-epidermal growth factor receptor monoclonal antibody ICR62 used alone and in combination with the EGFR tyrosine kinase inhibitor gefitinib

The anti-epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab has been approved for the treatment of patients with metastatic colorectal cancer. However, there is currently no reliable marker for response to therapy with the EGFR inhibitors. In this study, we investigated the sensitivity of 10 human colorectal tumor cell lines (DiFi, CCL218, CCL221, CCL225, CCL227, CCL228, CCL231, CCL235, CCL244, and HCT-116) to treatment with our anti-EGFR monoclonal antibody, ICR62, and/or the EGFR tyrosine kinase inhibitor, gefitinib. Of the cells examined, only DiFi contained high levels of constitutively active EGFR and were highly sensitive to treatment with both ICR62 (IC(50) = 0.52 nmol/L) and gefitinib (IC(50) = 27.5 nmol/L). In contrast, the growth of other tumor cell lines, which contained low levels of the EGFR, HER-2, and pAkt but comparable or even higher basal levels of phosphorylated mitogen-activated protein kinase (pMAPK), were relatively resistant to treatment with both inhibitors. Both ICR62 and gefitinib induced EGFR down-regulation, reduced the basal levels of pEGFR at five known tyrosine residues, pMAPK, and pAkt, and increased the sub-G(1) population in DiFi cells. However, treatment with a combination of ICR62 and gefitinib neither sensitized colorectal tumor cells that were insensitive to treatment with the single agent nor enhanced the growth-inhibitory effect of the single agent in DiFi cells. These results indicate that basal levels of pMAPK and pAkt are not good indicators of response to the EGFR inhibitors in colorectal cancer cells and dual targeting of the EGFR by a combination of ICR62 and gefitinib is not superior to treatment with a single agent.

Targeting the insulin-like growth factor axis as a cancer therapy

The insulin-like growth factor (IGF) axis has been implicated in malignant transformation and in tumor cell biology. Human population studies have demonstrated that high levels of circulating IGF-I are associated with an increased risk of certain malignancies. Many model systems show that IGFs stimulate tumor cell proliferation, survival and metastasis. In a new era of anticancer treatments aimed at tumor-specific targets, efforts are in progress for the development of novel anti-IGF therapies. Disrupting type I IGF-receptor (IGF-IR) function in vitro and in vivo results in tumor growth inhibition in several model systems. Antireceptor therapies in particular have provided encouraging results leading to the approval of the first Phase I human clinical trial targeting IGF-IR. Additional methods to decrease levels of circulating IGF-I and II have also been developed. In principle, a benefit of targeted therapies could be their relative lack of toxicity compared with conventional chemotherapy. Anti-IGF-IR therapies, however, raise theoretical concerns for the development of serious side effects, including diabetes. As targeted therapies against the IGF axis continue to be developed, efforts will need to be made to minimize the side effects that result from blocking normal ligand and receptor-induced functions.

Recent advances in targeted therapies for colorectal cancer

BACKGROUND

Recent advances in the molecular biology and genetics of colorectal cancer have led to the identification of potential therapeutic targets such as epidermal growth factor receptor, vascular endothelial growth factor and endothelial receptors.

OBJECTIVE

This review will examine the major therapeutic advances along with the preclinical basis justifying their combination with conventional therapeutic tools. This review will also critically consider current possibilities offered to identify responding patients.

DATA SOURCES

Preclinical and primary clinical trial results published in peer-review journals. The authors examined the relevance and subsequent inclusion of the data.

CONCLUSIONS

Cetuximab and bevacizumab provide new benefits in terms of the response rate and survival. There remain, however, important questions concerning, for instance, optimal combinations between conventional cytotoxic agents and targeted therapies and also between targeted drugs themselves. These new targeted treatments are costly and in this context the question of the identification of the right drug for the right patient is particularly relevant. Adequate tools in predicting the efficacy of targeted treatments are still needed.

Thymidine phosphorylase expression is associated with response to capecitabine plus irinotecan in patients with metastatic colorectal cancer

PURPOSE

To evaluate the clinical activity and toxicity of capecitabine plus irinotecan as first-line therapy for patients with metastatic colorectal cancer (mCRC), and to describe the association of expression of thymidine phosphorylase (TP), thymidylate synthase (TS), and dihydropyrimidine dehydrogenase (DPD) with antitumor activity.

PATIENTS AND METHODS

Patients with previously untreated mCRC received irinotecan days 1 and 8 intravenously, and capecitabine days 2 to 15 orally in 21-day cycles. Doses were irinotecan 125 mg/m2 and capecitabine 1,000 mg/m2 bid (n = 15; cohort 1), or irinotecan 100 mg/m2 and capecitabine 900 mg/m2 bid (n = 52; cohort 2). Tissues from primary and metastatic sites were assessed for TP, TS, and DPD gene and protein expression.

RESULTS

An unacceptable level of GI toxicity in the first 15 patients led to a protocol modification in starting doses. The response rate was 45% (30 of 67 patients). Overall survival was associated with TP expression assessed by immunohistochemistry in both primary tumors (P = .045) and metastases (P = .001). Objective tumor response was associated with TP expression in primary tumors (odds ratio, 4.77; 95% CI, 1.25 to 18.18), with a similar trend in metastases (odds ratio, 8.67; 95% CI, 0.95 to 79.1). TP gene expression in primary tumors was also associated with response.

CONCLUSION

These data indicate that capecitabine plus irinotecan is an active regimen against mCRC. The biomarker analysis (including metastatic tissue) was feasible in a multicenter setting, and provides preliminary evidence that TP expression may be a predictive marker for response.

Phase I trial of cetuximab in combination with capecitabine, weekly irinotecan, and radiotherapy as neoadjuvant therapy for rectal cancer

PURPOSE

To establish the feasibility and efficacy of chemotherapy with capecitabine, weekly irinotecan, cetuximab, and pelvic radiotherapy for patients with locally advanced rectal cancer.

METHODS AND MATERIALS

Twenty patients with rectal cancer (clinical Stage uT3-T4 or N+) received a standard dosing regimen of cetuximab (400 mg/m(2) on Day 1 and 250 mg/m(2) on Days 8, 15, 22, and 29) and escalating doses of irinotecan and capecitabine according to phase I methods: dose level I, irinotecan 40 mg/m(2) on Days 1, 8, 15, 22, and 29 and capecitabine 800 mg/m(2) on Days 1-38; dose level II, irinotecan 40 mg/m(2) and capecitabine 1000 mg/m(2); and dose level III, irinotecan 50 mg/m(2) and capecitabine 1000 mg/m(2). Radiotherapy was given to a dose of 50.4 Gy (45 Gy plus 5.4 Gy). Resection was scheduled 4-5 weeks after termination of chemoradiotherapy.

RESULTS

On dose level I, no dose-limiting toxicities occurred; however, Grade 3 diarrhea affected 1 of 6 patients on dose level II. Of 5 patients treated at dose level III, 2 exhibited dose-limiting toxicity (diarrhea in 2 and nausea/vomiting in 1). Therefore, dose level II was determined as the recommended dose for future studies. A total of 10 patients were treated on dose level II and received a mean relative dose intensity of 100% of cetuximab, 94% of irinotecan, and 95% of capecitabine. All patients underwent surgery. Five patients had a pathologically complete remission and six had microfoci of residual tumor only.

CONCLUSION

Preoperative chemoradiotherapy with cetuximab, capecitabine, and weekly irinotecan is feasible and well tolerated. The preliminary efficacy is very promising. Larger phase II trials are ongoing.

Randomized phase III trial results of panitumumab, a fully human anti-epidermal growth factor receptor monoclonal antibody, in metastatic colorectal cancer

Monoclonal antibodies against the epidermal growth factor receptor have proven efficacy as monotherapy and in combination with chemotherapy in patients with metastatic colorectal cancer (CRC: mCRC). Initial clinical trials in CRC used the human-murine chimeric monoclonal antibody cetuximab. Ongoing studies are being conducted to evaluate the efficacy and safety of the fully human anti-epiderman growth factor receptor monoclonal antibody panitumumab. The results of a phase III trial which compared panitumumab as a single agent to best supportive care in patients with previously treated metastatic CRC have recently been reported Pantitumumab therapy resulted in a 46% reduction in the risk of tumor progression and a partial response rate of 8%. Rash was reported in 90% of patients with increased severity significantly correlated with improved medium overall survival (OS). Further clinical studies re ongoing and planned to test panitumumab in combination with chemotherapy in first-line therapy of advanced-stage CRC and adjuvant treatment of colon cancer.

Phase II study of erlotinib (OSI-774) in patients with metastatic colorectal cancer

Erlotinib (Tarceva™, OSI-774), a potent epidermal growth factor receptor tyrosine kinase inhibitor (EGFR), was evaluated in a phase II study to assess its activity in patients with metastatic colorectal cancer. In all, 38 patients with metastatic colorectal cancer were treated with erlotinib at a continuous daily oral dose of 150 mg. Radiological evaluation was carried out every 8 weeks and tumour biopsies were performed before treatment and on day 8. Of 31 evaluable patients, 19 (61%) had progressive disease and 12 (39%) had stable disease (s.d.). The median time to progression for those patients having s.d. was 123 days (range 108–329 days). The most common adverse events were rash in 34 patients and diarrhoea in 23 patients. Correlative studies were conducted to investigate the effect of erlotinib on downstream signalling. Tumour tissue correlations were based on usable tissue from eight match paired tumour samples pre- and on therapy, and showed a statistically significant decrease in the median intensity of both pEGFR (P=0.008) and phospho-extracellular signal-regulated kinase (ERK) (P=0.008) a week after commencement of treatment. No other statistically significant change in tumour markers was observed. Erlotinib was well tolerated with the most common toxicities being rash and diarrhoea. More than one-third of evaluable patients had s.d. for a minimum of 8 weeks. Correlative studies showed a reduction in phosphorylated EGFR and ERK in tumour tissue post-treatment.

Molecular targeting and treatment of EGFRvIII-positive gliomas using boronated monoclonal antibody L8A4

PURPOSE

The purpose of the present study was to evaluate a boronated EGFRvIII-specific monoclonal antibody, L8A4, for boron neutron capture therapy (BNCT) of the receptor-positive rat glioma, F98(npEGFRvIII).

EXPERIMENTAL DESIGN

A heavily boronated polyamido amine (PAMAM) dendrimer (BD) was chemically linked to L8A4 by two heterobifunctional reagents, N-succinimidyl 3-(2-pyridyldithio)propionate and N-(k-maleimidoundecanoic acid)hydrazide. For in vivo studies, F98 wild-type receptor-negative or EGFRvIII human gene-transfected receptor-positive F98(npEGFRvIII) glioma cells were implanted i.c. into the brains of Fischer rats. Biodistribution studies were initiated 14 days later. Animals received [(125)I]BD-L8A4 by either convection enhanced delivery (CED) or direct i.t. injection and were euthanized 6, 12, 24, or 48 hours later.

RESULTS

At 6 hours, equivalent amounts of the bioconjugate were detected in receptor-positive and receptor-negative tumors, but by 24 hours the amounts retained by receptor-positive gliomas were 60.1% following CED and 43.7% following i.t. injection compared with 14.6% ID/g by receptor-negative tumors. Boron concentrations in normal brain, blood, liver, kidneys, and spleen all were at nondetectable levels (<0.5 microg/g) at the corresponding times. Based on these favorable biodistribution data, BNCT studies were initiated at the Massachusetts Institute of Technology Research Reactor-II. Rats received BD-L8A4 ( approximately 40 microg (10)B/ approximately 750 mug protein) by CED either alone or in combination with i.v. boronophenylalanine (BPA; 500 mg/kg). BNCT was carried out 24 hours after administration of the bioconjugate and 2.5 hours after i.v. injection of BPA for those animals that received both agents. Rats that received BD-L8A4 by CED in combination with i.v. BPA had a mean +/- SE survival time of 85.5 +/- 15.5 days with 20% long-term survivors (>6 months) and those that received BD-L8A4 alone had a mean +/- SE survival time of 70.4 +/- 11.1 days with 10% long-term survivors compared with 40.1 +/- 2.2 days for i.v. BPA and 30.3 +/- 1.6 and 26.3 +/- 1.1 days for irradiated and untreated controls, respectively.

CONCLUSIONS

These data convincingly show the therapeutic efficacy of molecular targeting of EGFRvIII using either boronated monoclonal antibody L8A4 alone or in combination with BPA and should provide a platform for the future development of combinations of high and low molecular weight delivery agents for BNCT of brain tumors.

The evolving role of cetuximab in non-small cell lung cancer

Cetuximab is a monoclonal antibody directed against the ligand binding site in the extracellular domain of the epidermal growth factor receptor (EGFR). Cetuximab is currently approved for the treatment of patients with refractory colorectal cancer. In locally advanced head and neck carcinoma, cetuximab in combination with radiotherapy significantly improved survival compared with radiotherapy alone, and this treatment awaits Food and Drug Administration approval. In previously treated non-small cell lung cancer, single-agent cetuximab produced an objective response in 3 of 66 eligible patients and a median survival of 8.1 months. Treatment was well tolerated, with skin rash as the principal toxicity. The vast majority of patients (60 of 66) expressed EGFR by immunohistochemistry but no correlation existed between response and EGFR mutations. Two single-arm phase II trials testing cetuximab in combination with a platinum-based doublet in previously untreated patients showed responses in the range of 26% to 29%, with median survival times of 10 to 11 months. A European phase II randomized trial tested cisplatin/vinorelbine with or without cetuximab as first-line therapy in 86 patients with advanced non-small-cell lung cancer. Overall efficacy was slightly superior in the cetuximab arm and a phase III trial is currently ongoing to definitively determine the role of cetuximab in this setting.

Epidermal growth factor receptor inhibitors in development for the treatment of non-small cell lung cancer

The epidermal growth factor receptor (EGFR) inhibitors erlotinib, gefitinib, and cetuximab have undergone extensive clinical testing and have established clinical activity in non-small cell lung cancer and other types of solid tumors. A number of newer inhibitors are currently in clinical development with different spectra of activity or mechanisms of receptor inhibition. These include monoclonal antibodies, such as panitumumab and matuzumab; dual inhibitors of EGFR and vascular endothelial growth factor receptor, such as ZD6474 and AEE788; inhibitors of multiple EGFR family members, such as lapatinib; and irreversible inhibitors, such as canertinib and HKI272. Preclinical studies suggest that several of these agents may have activity in tumors refractory to erlotinib or gefitinib. Among these agents, ZD6474 has undergone the most extensive clinical testing. The antitumor activity of ZD6474 in these two randomized phase II clinical trials in patients with non-small cell lung cancer was felt to be sufficiently promising to warrant phase III clinical testing. Several of the other EGFR inhibitors are also undergoing advanced clinical testing, either alone or in combination with other agents. EGFR has now been validated as a clinically relevant target, and several different types of agents inhibiting this receptor are currently in development. Future research will be needed to elucidate the role of these agents in patients with EGFR inhibitor-naive and EGFR inhibitor-refractory disease, to define the molecular characteristics that predict response, and to determine whether these drugs should be used in combination with other targeted agents or chemotherapy.

Screens using RNAi and cDNA expression as surrogates for genetics in mammalian tissue culture cells

We have developed methods for the automation of transfection-grade DNA preparation, high-throughput retroviral preparation, and highly parallel phenotypic screens to establish approaches that will allow investigators to examine in an unbiased manner the roles of proteins in mammalian cells. These methods have been used to raise or lower the levels of individual kinases in individual micro-well cultures either by cDNA or short hairpin RNA expression and will allow investigators to treat mammalian cells in culture in manners that are analogous to genetic screens in yeast. Our proof-of-principle experiments have been performed in human cells using repositories that represent over 75% of the protein, nucleotide, carbohydrate, lipid, and amino acid kinases in the human genome. These initial experiments have demonstrated the feasibility of two general types of screens. We have performed phenotypic screens to identify proteins with specific roles in a chosen function and genetic interaction screens to establish epistatic relations between different proteins. The results suggest that any phenotype that can be scored by a robust assay in tissue culture is amenable to these types of screens and that interactions between mammalian proteins can be established. These results point to the near-term goal of establishing comprehensive, unbiased screens that will allow queries on the roles of all human proteins.