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

Epidermal growth factor receptor inhibitors in cancer treatment

The epidermal growth factor receptor (EGFR) is a cellular transmembrane receptor with tyrosine kinase enzymatic activity which plays a key role in human cancer. EGFR-dependent signaling is involved in cancer cell proliferation, apoptosis, angiogenesis, invasion and metastasis. Targeting the EGFR is a valuable molecular approach in cancer therapy. Several anti-EGFR drugs are in Phase III clinical development as single agent or in combination with other anticancer modalities. Cetuximab (Erbitux), a chimeric human-mouse monoclonal immunoglobin (Ig)G1 antibody, which blocks ligand binding and functional activation of the EGFR, is currently registered in the USA, Switzerland and the European Union for the treatment of advanced, irinotecan-refractory colorectal cancer. Gefitinib, (Iressa), a small molecule EGFR-selective inhibitor of tyrosine kinase activity which blocks EGF autophosphorylation and activation, has been the first EGFR-targeting drug to be registered in 28 countries worldwide, including the USA, for the third-line treatment of chemoresistant non-small cell lung cancer patients. This review will focus on the preclinical background and on the clinical data with the anti-EGFR drugs in most advanced clinical development. Furthermore, a series of open clinical issues for the development of optimal strategies of using EGFR-targeting agents will be discussed.

Tailor-made chemotherapy for non-small cell lung cancer patients

The selection of the most effective chemotherapy treatment based on evaluation of biomarkers, that is, 'tailor-made chemotherapy', can improve the clinical outcome of non-small cell lung cancer patients, including early-stage tumors with a high metastatic potential and advanced-stage tumors with a low proliferation rate. Therefore, treatment would be chosen according to which drugs would be most effective in combating specific tumors. For example: 5-fluorouracil-derived agents would be used for tumors with a low expression of thymidylate synthase; gefitinib and erlotinib for tumors with epidermal growth factor receptor (EGFR) mutations or increased EGFR gene copy numbers; cisplatin and carboplatin for tumors with a low expression of excision repair cross complementing-1; and gemcitabine for tumors with a low expression of ribonucleotide reductase. The remaining populations of non-small cell lung cancers require chemotherapy using other drugs based on an evaluation of other targeted molecules.

Phase II trial alternating FOLFOX-6 and FOLFIRI regimens in second-line therapy of patients with metastatic colorectal cancer (FIREFOX study)

We assessed a schedule alternating 4 FOLFOX and 4 FOLFIRI cycles in 39 patients with 5-FU resistant metastatic colorectal cancer. Patients alternatively received 4 FOLFOX-6 cycles (oxaliplatin 100 mg/m(2), leucovorin 200 mg/m(2) d1 followed by bolus 400 mg/m(2) 5-FU and by a 46-hour 2,400 mg/m(2) 5-FU infusion, every 2 weeks), and 4 FOLFIRI cycles (oxaliplatin replaced by irinotecan 180 mg/m(2) d1) until progression or limiting toxicity. Eigteen patients achieved an objective response (46.1 percent). Median progression-free and overall survivals were 8.8 and 18.7 months, respectively. Only 2 patients (5.1 percent) had Grade 3 oxaliplatin-related sensory-neuropathy. This schedule had so promising efficacy and safety.

Surgical resection of hepatic metastases from colorectal cancer: a systematic review of published studies

No consensus on the indications for surgical resection of colorectal liver metastases exists. This systematic review has been undertaken to assess the published evidence for its efficacy and safety and to identify prognostic factors. Studies were identified by computerised and hand searches of the literature, scanning references and contacting investigators. The outcome measures were overall survival, disease-free survival, postoperative morbidity and mortality, quality of life and cost effectiveness, and a qualitative summary of the trends across all studies was produced. Only 30 of 529 independent studies met all the eligibility criteria for the review, and data on 30-day mortality and morbidity only were included from a further nine studies. The best available evidence came from prospective case series, but only two studies reported outcomes for all patients undergoing surgery. The remainder reported outcomes for selected groups of patients: those undergoing hepatic resection or those undergoing curative resection. Postoperative mortality rates were generally low (median 2.8%). The majority of studies described only serious postoperative morbidity, the most common being bile leak and associated perihepatic abscess. Approximately 30% of patients remained alive 5 years after resection and around two-thirds of these are disease free. The quality of the majority of published papers was poor and ascertaining the benefits of surgical resection of colorectal hepatic metastases is difficult in the absence of randomised trials. However, it is clear that there is group of patients with liver metastases who may become long-term disease- free survivors following hepatic resection. Such survival is rare in apparently comparable patients who do not have surgical treatment. Further work is needed to more accurately define this group of patients and to determine whether the addition of adjuvant treatments results in improved survival.

Phase II study of capecitabine, oxaliplatin, and erlotinib in previously treated patients with metastastic colorectal cancer

PURPOSE

To investigate the combination of erlotinib, capecitabine, and oxaliplatin in patients who were previously treated for metastatic colorectal cancer.

PATIENTS AND METHODS

Patients were eligible if they had metastatic colorectal cancer that progressed, were intolerant to first-line chemotherapy, or had disease recurrence within 1 year of adjuvant therapy for early-stage disease. Each 21-day cycle consisted of daily oral erlotinib at 150 mg, oral capecitabine at 1,000 mg/m2 (reduced to 750 mg/m2 after the first 13 patients) twice a day on days 1 to 14, and intravenous oxaliplatin at 130 mg/m2 on day 1.

RESULTS

Thirty-two patients were enrolled onto this phase II study. By intention-to-treat analyses, eight patients (25%) experienced a partial response and 14 patients (44%) had stable disease for at least 12 weeks. The median progression-free survival was 5.4 months and the median overall survival was 14.7 months. These results were essentially unchanged when limited to the cohort of patients (78%) who received prior irinotecan for metastatic colorectal cancer. Most common grade 3 to 4 toxicities included diarrhea (38%), nausea/emesis (19%), fatigue (16%), dehydration (16%), and dermatitis (13%); grade 3 or 4 toxicities were reduced with a lower starting dose of capecitabine.

CONCLUSION

The combination of capecitabine, oxaliplatin, and erlotinib seems to have promising activity against metastatic colorectal cancer in patients who received prior chemotherapy, with a relatively higher response rate and progression-free survival compared with previous reports of either infusional FU, leucovorin, and oxaliplatin or capecitabine and oxaliplatin in similar patient populations.

Treatment of non-small cell lung cancer with intensity-modulated radiation therapy in combination with cetuximab: the NEAR protocol (NCT00115518)

BACKGROUND

Even today, treatment of Stage III NSCLC still poses a serious challenge. So far, surgical resection is the treatment of choice. Patients whose tumour is not resectable or who are unfit to undergo surgery are usually referred to a combined radio-chemotherapy. However, combined radio-chemotherapeutic treatment is also associated with sometimes marked side effects but has been shown to be more efficient than radiation therapy alone. Nevertheless, there is a significant subset of patients whose overall condition does not permit administration of chemotherapy in a combined-modality treatment. It could be demonstrated though, that NSCLCs often exhibit over-expression of EGF-receptors hence providing an excellent target for the monoclonal EGFR-antagonist cetuximab (Erbitux) which has already been shown to be effective in colorectal as well as head-and-neck tumours with comparatively mild side-effects.

METHODS/DESIGN

The NEAR trial is a prospective phase II feasibility study combining a monoclonal EGF-receptor antibody with loco-regional irradiation in patients with stage III NSCLC. This trial aims at testing the combination's efficacy and rate of development of distant metastases with an accrual of 30 patients. Patients receive weekly infusions of cetuximab (Erbitux) plus loco-regional radiation therapy as intensity-modulated radiation therapy. After conclusion of radiation treatment patients continue to receive weekly cetuximab for 13 more cycles.

DISCUSSION

The primary objective of the NEAR trial is to evaluate toxicities and feasibility of the combined treatment with cetuximab (Erbitux) and IMRT loco-regional irradiation. Secondary objectives are remission rates, 3-year-survival and local/systemic progression-free survival.

EGFR tyrosine kinase inhibitors decrease VEGF expression by both hypoxia-inducible factor (HIF)-1-independent and HIF-1-dependent mechanisms

Epidermal growth factor receptor (EGFR) inhibitors can decrease vascular endothelial growth factor (VEGF) expression and tumor angiogenesis. In the current study, we investigate the molecular pathways by which this occurs using two drugs that have been used in the clinic, gefitinib (Iressa) and erlotinib (Tarceva). The decrease in VEGF expression by gefitinib in SQ20B squamous cell carcinoma cells was opposed by adenoviral expression of Akt in these cells. The hypoxia-inducible factor-1 (HIF-1) binding site located at approximately -1 kbp in the VEGF promoter was not required for down-regulation of promoter activity by gefitinib under normoxia. Furthermore, the drug decreased activity of a reporter containing the -88/+54 region. In a gel shift assay, gefitinib led to decreased retardation of a labeled DNA oligonucleotide probe corresponding to the -88/-66 region of the VEGF promoter, which contains Sp1 binding sites. These effects of gefitinib on VEGF promoter activity and DNA binding were both reversed by Akt expression. Phosphorylation of Sp1 was decreased in the presence of gefitinib. Gefitinib also decreases VEGF expression by decreasing HIF-1alpha expression. This occurs due to decreased protein translation without any change in the level of HIF-1alpha mRNA. Together, these results suggest that gefitinib decreases VEGF expression both by decreasing Sp1 binding to the proximal core VEGF promoter and by down-regulating HIF-1alpha expression. Similar results were obtained with erlotinib in SQ20B and gefitinib in HSC3 squamous carcinoma cells. These results indicate that there are at least two separate mechanisms by which EGFR inhibitors decrease VEGF expression.

Minimally invasive pharmacokinetic and pharmacodynamic technologies in hypothesis-testing clinical trials of innovative therapies

Clinical trials of new cancer drugs should ideally include measurements of parameters such as molecular target expression, pharmacokinetic (PK) behavior, and pharmacodynamic (PD) endpoints that can be linked to measures of clinical effect. Appropriate PK/PD biomarkers facilitate proof-of-concept demonstrations for target modulation; enhance the rational selection of an optimal drug dose and schedule; aid decision-making, such as whether to continue or close a drug development project; and may explain or predict clinical outcomes. In addition, measurement of PK/PD biomarkers can minimize uncertainty associated with predicting drug safety and efficacy, reduce the high levels of drug attrition during development, accelerate drug approval, and decrease the overall costs of drug development. However, there are many challenges in the development and implementation of biomarkers that probably explain their disappointingly low implementation in phase I trials. The Pharmacodynamic/Pharmacokinetic Technologies Advisory committee of Cancer Research UK has found that submissions for phase I trials of new cancer drugs in the United Kingdom often lack detailed information about PK and/or PD endpoints, which leads to suboptimal information being obtained in those trials or to delays in starting the trials while PK/PD methods are developed and validated. Minimally invasive PK/PD technologies have logistic and ethical advantages over more invasive technologies. Here we review these technologies, emphasizing magnetic resonance spectroscopy and positron emission tomography, which provide detailed functional and metabolic information. Assays that measure effects of drugs on important biologic pathways and processes are likely to be more cost-effective than those that measure specific molecular targets. Development, validation, and implementation of minimally invasive PK/PD methods are encouraged.

Efficacy of Cetuximab After Treatment with Oral Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor—Based Chemotherapy in Metastatic Colorectal Cancer

PURPOSE

We studied the efficacy of cetuximab therapy in patients with metastatic colorectal cancer (mCRC) previously treated with an oral inhibitor of the tyrosine kinase domain of the epidermal growth factor receptor.

PATIENTS AND METHODS

We reviewed the posttrial records of 73 patients with mCRC who participated in 1 of 3 clinical trials that examined a combination of gefitinib or erlotinib with standard cytotoxic chemotherapy. Medical and pharmacy records were used to identify patients who were subsequently treated with cetuximab-based therapy. Computed tomography scans during cetuximab-based therapy were reviewed, and the clinical activity of cetuximab was assessed by response rate using Response Evaluation Criteria in Solid Tumors and progression-free survival.

RESULTS

Twenty-four patients with mCRC previously treated with gefitinib or erlotinib and combination cytotoxic chemotherapy who subsequently received cetuximab-based therapy were identified. While receiving cetuximab-based therapy, no patient experienced a partial or complete response; however, 3 patients (16% of patients with available scans for formal measurements) had a minor response, defined as a 15%-29.9% decrease in the sum of longest dimensions of target lesions, and 72% had stable disease. The progression-free survival was 5.1 months for all patients and 6 months for patients who had documented progression of disease while previously receiving gefitinib- or erlotinib-based therapy.

CONCLUSION

Cetuximab appears to have clinical benefit in patients with mCRC previously treated with a chemotherapy regimen that included an oral tyrosine kinase inhibitor of epidermal growth factor receptor. Whether these results apply to other cancer types is unknown but worthy of further study.

Targeted Agents for Adjuvant Therapy of Colon Cancer

Among patients with colorectal cancer (CRC) diagnosed in the United States, 37.2% are diagnosed with stage III and 27.9% with stage II disease. In locoregionally advanced CRC, surgery is the primary treatment modality and has a curative intent. The survival depends on the pathologic stage and varies from 30%-60% for stage III to 60%-80% for stage II. However, as much as 40%-50% of patients will relapse and require additional treatment of the disease. Clinical failure after resection of CRC is predominantly secondary to the clinical progression of previously undetected distant metastatic disease. Until very recently, the absolute benefit for survival obtained with adjuvant therapy compared with control was about 6%. Introduction of oxaliplatin in the adjuvant setting has shown a reduction of 23% in the risk of relapse when compared with 5-fluorouracil alone (MOSAIC). Recent phase III studies have shown that targeted agents improved survival in patients with advanced-stage CRC. Bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, is the first antiangiogenic drug to show improved efficacy when used in combination with irinotecan and oxaliplatin for first- and second-line treatment of CRC. Cetuximab, another monoclonal antibody targeting epidermal growth factor receptor, has shown efficacy in third-line therapy and promising results in first-line phase II studies. There is great interest in whether the biologic agents bevacizumab and cetuximab can improve survival in the adjuvant-therapy setting. This article reviews the adjuvant therapy for colon cancer and discusses the potential role and current trials involving the targeted agents.

Treatment of hepatic metastases from colorectal cancer: Many doubts, some certainties

About 50% of patients with colorectal cancer (CCR) are destined to develop hepatic metastases during the course of the disease. Surgery is currently the only potentially curative treatment with a five year survival rate after hepatectomy from 26% to 49%. The criteria for resectability are now less rigid than in the past and the tendency to adopt a more aggressive treatment of metastatic lesions is the rule. Systemic infusion chemotherapies based on 5-fluorouracil (5-FU), oxaliplatin (OHP) and irinotecan (CPT-11) are well tolerated and have been shown to be effective in non-operable patients. These regimens allow surgery for patients who are initially not suitable for resection, giving them a probability of survival at five years similar to that of patients operated on at diagnosis. Intra-arterial infusion chemotherapy (HAI) is very effective in inducing objective responses, but is costly, difficult to manage and encumbered by major side effects, so that its application is necessarily limited to centres with specific experience. However, despite the broader criteria and recent advances of chemotherapy, surgery is not possible in most patients. The role of other local therapeutic techniques like cryosurgery (CS) and radiofrequency ablation (RF), alone or combined with surgery or chemotherapy, is not yet established in a multidisciplinary therapeutic approach. Roughly two thirds of patients relapse during the first two years after surgery suggesting appropriate post-operative chemotherapy treatment after hepatic resection may be indicated, but no randomised studies have been published to date. In case of relapse, another hepatectomy should be considered. The role of novel targeted therapies in pre-operative, post-operative and palliative management has yet to be evaluated.

Evolving role of antineoplastic agents in colorectal cancer

PURPOSE

The epidemiology, natural history, patient presentation, staging, prognosis, and treatment of colorectal cancer are described.

SUMMARY

Colorectal cancer is a common malignancy that usually is not diagnosed when it is localized because it typically is asymptomatic in the early stages. Various cancer chemotherapeutic agents with different toxicities are available, including the recently introduced recombinant humanized immunoglobulin G(1) monoclonal antibodies cetuximab and bevacizumab. Chemotherapy may be used with or without surgery in patients with advanced or metastatic colorectal cancer, usually for palliation rather than a cure. The results of clinical trials suggest that patients with advanced or metastatic colorectal cancer probably should receive 5-fluorouracil (5-FU)/leucovorin, irinotecan, oxaliplatin, bevacizumab, and cetuximab at some time in the course of treatment, although the preferred combinations and sequence of these agents remain to be determined. After surgery, adjuvant chemotherapy may be used for curative purposes in patients with stage III disease and some patients with stage II disease at high risk for disease recurrence and death. Although 5-FU plus leucovorin has been the standard adjuvant therapy, clinical trials have demonstrated that adding oxaliplatin or using capecitabine alone instead is an alternative.

CONCLUSION

Several recently introduced chemotherapeutic agents appear promising for the treatment of colorectal cancer, but additional clinical research is needed to identify the ideal combinations and sequence of these agents.

Preoperative and adjuvant treatment of localized rectal cancer

Although postoperative chemoradiation has a proven role in the treatment of stage II to III localized rectal cancer, recent trials have demonstrated the role of preoperative chemoradiation. A recent randomized trial has shown that preoperative chemoradiation yields higher rates of local control and sphincter preservation and lower rates of toxicity, compared with postoperative chemoradiation. Randomized trials have also shown that preoperative chemoradiation yields higher rates of pathologic complete response and local control, compared with radiotherapy alone. In this article, we review recent trials on preoperative and adjuvant therapy of localized rectal cancer. The roles of newer agents, such as capecitabine, oxaliplatin, and bevacizumab, are also discussed, and other key issues in the treatment of localized rectal cancer are reviewed.

Individualizing chemotherapeutic treatment of colorectal cancer

PURPOSE

Patient-specific factors that enter into decisions about the chemotherapy used to treat colorectal cancer are illustrated in several case studies.

SUMMARY

Genetic polymorphisms in genes that encode drug-metabolizing enzymes may affect the disposition and the risk for toxicity from chemotherapy agents used to treat colorectal cancer. Severe toxicity from 5-fluorouracil has been attributed to a deficiency in dihydropyrimidine dehydrogenase (DPD), but currently there is no widely used genetic test for DPD deficiency. An assay is available for genotypic testing of the enzyme UGT1A1, which is predictive of toxicity from irinotecan. Advanced age, prior pelvic or abdominal radiotherapy, a poor performance status, and increased pretreatment total bilirubin concentration also are associated with irinotecan-related toxicity. A reduction in irinotecan dosage or use of an alternative agent may be warranted in patients with risk factors for toxicity. Positive epidermal growth factor receptor (EGFR) expression by immunohistochemical (IHC) staining does not necessarily predict the response to cetuximab, a monoclonal antibody that binds EGFR, possibly because of the low sensitivity of the test. Carcinoembryonic antigen (CEA) is the tumor marker of choice for monitoring for progression of colorectal cancer.

CONCLUSION

Individualizing chemotherapy based on disease stage, pharmacogenetics, prior therapy, patient age, performance status, and CEA level may help to optimize outcomes from chemotherapy for patients with colorectal cancer.

Epidermal growth factor receptor expression and activation in neuroendocrine tumours

Epidermal growth factor receptor (EGFR) is expressed in many cancers and is associated with poor prognosis. EGFR activation pathways have been well characterised using tumour cell lines and are known to involve EGFR activation through autophosphorylation. Phosphorylation of downstream signalling molecules, such as ERK1/2 (extra-cellular regulated kinase 1 and 2) and PKB/Akt (protein kinase B), leads to enhanced tumour cell survival and proliferation. Although EGFR expression has been determined in neuroendocrine tumour tissue, its activation and subsequent effects on the downstream signalling molecules, ERK1/2 and Akt, have not been studied. We therefore planned to determine the role of EGFR in neuroendocrine tumours (NETs) by determining its pattern of expression and activation, and the subsequent activation of downstream signalling molecules ERK1/2 and Akt. Paraffin-embedded tumour tissue was available from 98 patients with NETs (39 foregut, 42 midgut, four hindgut, five paragangliomas, and four of unknown origin). Immunohistochemical evaluation was performed for the expression of EGFR, p-EGFR, p-Akt, and p-ERK1/2. Ninety-six percent of tumour samples were positive for EGFR expression; 63% were positive for activated EGFR; 76% were positive for activated Akt; and 96% were positive for activated ERK1/2. Importantly, the histological score for the activation of Akt and ERK1/2 correlated with the histological score for activated EGFR. These data provide a rationale for considering EGFR inhibitors in the treatment of NETs. Additionally, direct inhibition of Akt and ERK1/2 may provide further therapeutic options in the treatment of NETs in the future.

Estimating Costs of Care for Patients with Newly Diagnosed Metastatic Colorectal Cancer

BACKGROUND

This study examines the resource use patterns and costs of care for patients with incident metastatic colorectal cancer (mCRC) based on analyses of retrospective claims data from selected health plans in the United States.

PATIENTS AND METHODS

A case-control analysis was performed using claims from years 1998-2004. Incident mCRC cases were identified based on evidence of a colorectal cancer diagnosis and a metastatic disease diagnosis. Incident mCRC cases could have no other evidence of cancer in the 1-year period before the date of their first mCRC diagnosis. Cases were matched to non-mCRC controls based on age, sex, geographic region, and duration of plan enrollment. Costs were evaluated by phase of disease: diagnosis, treatment, or death phases. Ordinary least squares regressions were performed to evaluate impact of covariates in each phase.

RESULTS

Total costs in the follow-up period averaged $97,031 more for mCRC cases than for controls. The main cost drivers for mCRC were hospitalizations ($37,369) and specialist visits ($34,582), which included chemotherapy administration. Approximately 40% of the 672 patients with mCRC who qualified for the phase analysis were identified with a fatal event during follow-up. Monthly costs were similar in the diagnostic phase ($12,205) and death phase ($12,328), but were significantly lower in the treatment phase ($4722). Both mean/median monthly costs increased over time during the study period, regardless of disease phase.

CONCLUSION

The economic burden of mCRC is substantial for patients with commercial health plans in the United States, and costs of care have increased substantially in recent years.

Cetuximab and irinotecan as third-line therapy in advanced colorectal cancer patients: a single centre phase II trial

The epidermal growth factor receptor (EGFR), which participates in signalling pathways that are deregulated in cancer cells, is frequently mutated in colorectal-cancer cells. Cetuximab is a monoclonal antibody that specifically blocks the EGFR. We evaluated the efficacy of cetuximab in weekly combination with irinotecan in metastatic colorectal cancer patients refractory to previous treatments based on oxaliplatin or irinotecan. We included 55 heavily pretreated patients (colon/rectum: 34/11, M/F: 16/29, median age 63 years, range: 27–79) whose disease had progressed during or within an oxaliplatin-based first-line chemotherapy and a irinotecan-based second-line regimen. Patients were followed for tumour response and were also evaluated for the time to tumour progression, and safety of treatment. Cetuximab was given at an initial dose of 400 mg m⁻², followed by weekly infusions of 250 mg m⁻². Irinotecan was administered weekly at the dose of 90 mg m⁻². All patients were assessable for treatment efficacy and safety response rate was 25.4% (95% CI: 21.7–39.6%); 38.2% (95 CI: 18.6–39.8%) of patients showed a disease stability as the best response. As a consequence, the overall tumour control rate was 63.6% (95% CI: 46.4–70.6%). The median time to progression was 4.7 months (95% CI: 2.5–7.1 months) and the median survival time was 9.8 months (95% CI: 3.9–10.1 months). The most common G3-4 noncutaneous side toxicities were: diarrhoea (16.4%), fatigue (12.7%) and stomatitis (7.3%). 89.1% of patients developed skin toxicity and 32.6% of cases was of grade 3–4. No allergic reactions were identified at any courses in any patients. Fever was documented in 27.3% of patients and was most commonly recorded after the first administration. Cetuximab has clinically significant activity even in heavily pretreated colorectal cancer patients progressed after both oxaliplatin and irinotecan-based chemotherapy regimens.

Potent Antitumor Activity of an Auristatin-Conjugated, Fully Human Monoclonal Antibody to Prostate-Specific Membrane Antigen

Prostate-specific membrane antigen (PSMA) is the prototypic cell-surface marker of prostate cancer and provides an attractive target for monoclonal antibody (mAb) targeted therapies. In this study, a novel antibody-drug conjugate (ADC) was generated by linking a fully human PSMA mAb to monomethylauristatin E (MMAE), a potent inhibitor of tubulin polymerization. The PSMA ADC was evaluated for antitumor activity in vitro and in a mouse xenograft model of androgen-independent human prostate cancer. The PSMA ADC eliminated PSMA-expressing cells with picomolar potency and >700-fold selectivity in culture. When used to treat mice with established human C4-2 tumors, the PSMA ADC significantly improved median survival 9-fold relative to vehicle or isotype-matched ADC (P = 0.0018) without toxicity. Treatment effects were also manifest as significant (P = 0.0068) reduction in serum levels of prostate-specific antigen (PSA). Importantly, 40% of treated animals had no detectable tumor or measurable PSA at day 500 and could be considered cured. The findings support development of PSMA antibody-auristatin conjugates for therapy of prostate cancer.

Multicenter phase II study of gemcitabine and oxaliplatin (GEMOX) as second-line chemotherapy in colorectal cancer patients pretreated with 5-fluorouracil plus irinotecan

PURPOSE

To evaluate the efficacy and tolerance of the gemcitabine/oxaliplatin (GEMOX) combination as second-line chemotherapy for patients with advanced colorectal cancer (CRC) pretreated with an irinotecan (CPT-11)/5-fluorouracil (5-FU)/leucovorin (LV) regimen.

PATIENTS AND METHODS

Patients with documented disease progression during or after first-line treatment with CPT-11 and 5-FU/LV were enrolled. Gemcitabine (1,000 mg/m(2) days 1 and 8) and oxaliplatin (100 mg/m(2) day 1) were administered every 3 weeks.

RESULTS

Partial responses were observed in 6 of the 34 (17.7%) patients enrolled (intention-to-treat analysis; overall response rate: 17.7%; 95% confidence interval 4.8-30.5%). Eight (23.5%) patients experienced disease stabilization and 20 (59%) disease progression (tumor growth control rate = 41.2%). The median duration of response was 5.5 months, and the median time to tumor progression 2.7 months. The median overall survival was 9.1 months (1-year survival rate: 44.0%). Grade 3 neutropenia and thrombocytopenia occurred in 18 and 15% of the patients, respectively. Other severe non-hematologic toxicities were rare.

CONCLUSION

The interesting tumor growth control rate and the favorable toxicity profile of the GEMOX regimen in pretreated patients with advanced CRC strongly suggest that this regimen may provide an alternative therapeutic option for this group of patients.

Novel kinase inhibitors in renal cell carcinoma: progressive development of static agents

The rapidly expanding knowledge regarding neoplastic diseases is providing a plethora of new targets for drug discovery and development as exemplified by recent data in renal cell carcinoma. The initial experience with molecularly "targeted" agents has demonstrated that development of the newer non-cytotoxic agents will provide unique challenges requiring modification of many traditional drug development concepts and methods. We discuss recently reported data from a few renal cell carcinoma trials with putative cytostatic agents and highlight issues that need to be addressed for efficient development of cytostatic agents during various phases of clinical development.

Recent advances in biomarkers for cancer diagnosis and treatment

With the availability of new technologies and the increased interest of medical practitioners to use molecular biomarkers in early detection and diagnosis, and in the prediction of therapeutic treatment efficacy and clinical outcomes, the academic and research institutions, as well as the pharmaceutical industry, have increased their efforts to develop novel molecular biomarkers for several human diseases, including cancer. The identification of molecular biomarkers also enables the development of a new generation of diagnostic products and to integrate diagnostics and therapeutics. This integrated approach will aid in 'individualizing' the medical practice. Here, we address issues related to the development of biomarkers, novel technological platforms used for drug development, future technologies and strategies for validating biomarkers for their clinical utility.

Pharmacogenomic identification of novel determinants of response to chemotherapy in colon cancer

DNA microarray analysis was used to analyze the transcriptional profile of HCT116 colorectal cancer cells that were treated with 5-fluorouracil (5-FU) or oxaliplatin and selected for resistance to these agents. Bioinformatic analyses identified sets of genes that were constitutively dysregulated in drug-resistant cells and transiently altered following acute exposure of parental cells to drug. We propose that these genes may represent molecular signatures of sensitivity to 5-FU and oxaliplatin. Using real-time reverse transcription-PCR (RT-PCR), the robustness of our microarray data was shown with a strong overall concordance of expression trends for > or =82% (oxaliplatin) and > or =85% (5-FU) of a representative subset of genes. Furthermore, strong correlations between the microarray and real-time RT-PCR measurements of average fold changes in gene expression were observed for both the 5-FU (R(2) > or = 0.73) and oxaliplatin gene sets (R(2) > or = 0.63). Functional analysis of three genes identified in the microarray study [prostate-derived factor (PDF), calretinin, and spermidine/spermine N(1)-acetyl transferase (SSAT)] revealed their importance as novel regulators of cytotoxic drug response. These data show the power of this novel microarray-based approach to identify genes which may be important markers of response to treatment and/or targets for therapeutic intervention.

KRAS Mutation Status Is Predictive of Response to Cetuximab Therapy in Colorectal Cancer

The anti-epidermal growth factor receptor (anti-EGFR) cetuximab has been proven to be efficient in metastatic colorectal cancer. The molecular mechanisms underlying the clinical response to this drug remain unknown. Genetic alterations of the intracellular effectors involved in EGFR-related signaling pathways may have an effect on response to this targeted therapy. In this study, tumors from 30 metastatic colorectal cancer patients treated by cetuximab were screened for KRAS, BRAF, and PIK3CA mutation by direct sequencing and for EGFR copy number by chromogenic in situ hybridization. Eleven of the 30 patients (37%) responded to cetuximab. A KRAS mutation was found in 13 tumors (43%) and was significantly associated with the absence of response to cetuximab (KRAS mutation in 0% of the 11 responder patients versus 68.4% of the 19 nonresponder patients; P = 0.0003). The overall survival of patients without KRAS mutation in their tumor was significantly higher compared with those patients with a mutated tumor (P = 0.016; median, 16.3 versus 6.9 months). An increased EGFR copy number was found in 3 patients (10%) and was significantly associated with an objective tumor response to cetuximab (P = 0.04). In conclusion, in this study, KRAS mutations are a predictor of resistance to cetuximab therapy and are associated with a worse prognosis. The EGFR amplification, which is not as frequent as initially reported, is also associated with response to this treatment.

Beyond 5-fluorouracil: new horizons in systemic therapy for advanced colorectal cancer

Worldwide, colorectal cancer is a common cancer and a major cause of morbidity and mortality. Patients frequently present with, or later develop, metastatic disease. Median survival with supportive care alone is approximately 6 - 8 months. However, a number of recent developments have greatly increased the range of therapeutic options, improving median survival to > 20 months. Cytotoxic agents such as capecitabine, irinotecan and oxaliplatin are now established treatment strategies. In parallel, an improved understanding of tumour biology has led to the development of non-cytotoxic targeted therapies. Examples include bevacizumab (targeting tumour angiogenesis) and cetuximab (targeting the epidermal growth factor receptor). These agents have recently been incorporated into standard management. This paper reviews these and other advances in the care of patients with advanced colorectal cancer and discusses a number of agents that are currently under development.

Current issues in adjuvant treatment of stage II colon cancer

BACKGROUND

Adjuvant chemotherapy with 5-fluorouracil modulated by folinic acid, combined with oxaliplatin, has now become an accepted standard of care for patients with stage III colon cancer. In contrast, the use of adjuvant therapy for stage II patients remains controversial, and the identification of reliable prognostic factors to aid therapeutic decision making is crucial.

METHODS

The authors critically review the results of clinical trials and meta-analyses investigating the value of adjuvant chemotherapy for stage II patients, emphasizing the heterogeneous nature of this population and the difficulty of performing clinical trials with sufficient power to reliably assess treatment efficacy. They also discuss the evidence concerning potential prognostic factors, particularly molecular markers.

RESULTS

Available clinical trial data do not support the routine use of adjuvant chemotherapy for all stage II patients but suggest that it should be considered, particularly for certain high-risk patients. Recent guidelines advocate considering factors such as tumor differentiation, tumor perforation, number of lymph nodes examined, and T stage when assessing the likely benefit:risk ratio. Microsatellite instability and allelic imbalance seem to be strong predictors of good and poor prognosis, respectively, and in the near future, therapeutic decision-making models are likely to be further refined by the inclusion of such molecular markers.

CONCLUSIONS

There is growing evidence that the prognosis of certain stage II patients with unfavorable prognostic factors can be improved by adjuvant chemotherapy, and increasingly refined tools are now available to define those most likely to benefit. Referral of stage II patients for individual assessment is strongly recommended.

Dermatologic toxicity of chemotherapeutic agents

Due to its high metabolic rate, skin represents one of the major target organs of chemotherapy-associated toxicity. Reactions range from common, nonspecific exanthematous eruptions to rare but distinctive cutaneous lesions that may not become apparent until a drug transitions from clinical trials to widespread oncologic use. The challenge of the physician is to recognize reaction patterns that reflect a drug reaction, identify a likely causative drug, and determine whether the reaction is a dose-limiting toxicity. This review will focus on the cutaneous side effects of the newer classes of chemotherapy drugs, including targeted monoclonal antibody therapy and small molecule inhibitors.

Anti-EGFR strategies as an incremental step for the treatment of colorectal cancer patients: moving from scientific evidence to clinical practice

The epidermal growth factor receptor (EGFR) is a 170,000 Da transmembrane glycoprotein involved in signalling pathways affecting cellular growth, differentiation and proliferation. An abnormal overexpression of the EGFR has been described in many human tumours and implicated in the development and prognosis of malignancies, thus representing not only a possible prognostic marker, but primarily a rational molecular target for a new class of anticancer agents. Several clinical trials have been reported with the use of EGFR-targeted monoclonal antibodies and tyrosine kinase inhibitors, mainly in combination with chemotherapy for advanced colorectal cancer patients. Taken together, results available so far suggest that anti-EGFR treatment strategies represent an incremental step for the the treatment of colorectal cencer patients with a manageable and acceptable toxicity profile. Nevertheless, many critical issues are yet unresolved, such as the optimal chemotherapy regimen to combine with anti-EGFR treatment and the most adequate patients setting. Moreover, the biological selection of colorectal tumours most likely to benefit from this treatment approach is still to be defined.

Surgical treatment of liver metastases of colorectal cancer: Strategies and controversies in 2006

AIMS

To review the latest strategies and controversies in the surgical treatment of liver metastases of colorectal cancer systemically and comprehensively.

METHODS

A medline based literature search on relevant topics was performed in PubMed for key articles concerning the novel strategies and controversies in the management of liver metastases of colorectal cancer. Some information was obtained from 'Proc Am Soc Clin Oncol' published recently. The findings and discussions were related to our own experiences.

RESULTS

Although for well-indicated patients, a consensus has been reached that hepatic resection is the only management that could provide the patients curability, there still exist many controversies, such as the prognostic evaluation, contraindications to hepatic resection, treatment for synchronous liver metastases, the place of laparoscopic surgery, etc. Meanwhile, various strategies to improve the respectabilities are available, including neoadjuvant chemotherapy, portal vein embolization, two stage hepatectomy, and some locally ablative approaches. The current condition is difficult and sometimes confusing for a relevant surgeon when designing treatment protocols for more complex diseases.

CONCLUSION

As the advancing of the management of liver metastases of colorectal cancer, more patients will become candidates for and benefit from potentially curative surgical resections. Optimal effect could only be achieved when used in a manner tailored to the individual patient.

Targeting insulin-like growth factor pathways

Some cancer cells depend on the function of specific molecules for their growth, survival, and metastatic potential. Targeting of these critical molecules has arguably been the best therapy for cancer as demonstrated by the success of tamoxifen and trastuzumab in breast cancer. This review will evaluate the type I IGF receptor (IGF-IR) as a potential target for cancer therapy. As new drugs come forward targeting this receptor system, several issues will need to be addressed in the early clinical trials using these agents.

High dose chemotherapy with autologous hematopoietic stem cell support for solid tumors other than breast cancer in adults

Since the early 1980s high dose chemotherapy with autologous hematopoietic stem cell support was adopted by many oncologists as a potentially curative option for solid tumors, supported by a strong rationale from laboratory studies and apparently convincing results of early phase II studies. As a result, the number and size of randomized trials comparing this approach with conventional chemotherapy initiated (and often abandoned before completion) to prove or disprove its value was largely insufficient. In fact, with the possible exception of breast carcinoma, the benefit of a greater escalation of dose of chemotherapy with stem cell support in solid tumors is still unsettled and many oncologists believe that this approach should cease. In this article, we critically review and comment on the data from studies of high dose chemotherapy so far reported in adult patients with small cell lung cancer, ovarian cancer, germ cell tumors and sarcomas.

Targeted therapies for esophageal cancer

Esophageal cancer is a highly aggressive neoplasm. In 2005, 14,520 Americans will be diagnosed with esophageal cancer, and more than 90% will die of their disease. On a global basis, cancer of the esophagus is the sixth leading cause of cancer death worldwide. In fact, gastric and esophageal cancers together accounted for nearly 1.3 million new cases and 980,000 deaths worldwide in 2000-more than lung, breast, or colorectal cancer. Although esophageal squamous cell carcinoma cases have steadily declined, the incidence of gastroesophageal junction adenocarcinoma has increased 4%-10% per year among U.S. men since 1976, more rapidly than for any other cancer type, and parallels rises in population trends in obesity and reflux disease. With advances in surgical techniques and treatment, the prognosis of esophageal cancer has slowly improved over the past three decades. However, the 5-year overall survival rate (14%) remains poor, even in comparison with the dismal survival rates (4%) from the 1970s. The underlying reasons for this disappointingly low survival rate are multifold: (a) ineffective screening tools and guidelines; (b) cancer detection at an advanced stage, with over 50% of patients with unresectable disease or distant metastasis at presentation; (c) high risk for recurrent disease after esophagectomy or definitive chemoradiotherapy; (d) unreliable noninvasive tools to measure complete response to chemoradiotherapy; and (e) limited survival achieved with palliative chemotherapy alone for patients with metastatic or unresectable disease. Clearly, additional strategies are needed to detect esophageal cancer earlier and to improve our systemic treatment options. Over the past decade, the field of drug development has been transformed with the identification of and ability to direct treatment at specific molecular targets. This review focuses on novel targeted treatments in development for esophageal squamous cell carcinoma and distal esophageal and gastroesophageal junction adenocarcinoma.

EGFR in colorectal cancer: more than a simple receptor

BACKGROUND

Advances in the understanding of tumor biology have led to the development of targeted therapies allowing progress in colorectal cancer treatment. One of the most promising targets is the epidermal growth factor receptor (EGFR).

METHOD

The presence and distribution of high- and low-affinity EGFR was investigated retrospectively in a group of 82 colorectal cancer samples (43 normal colon-colon cancer paired samples) using a specific ligand binding assay (Scatchard Analysis).

FINDINGS

A large majority of tumor samples exhibited one class of high-affinity binding sites (78%). Eighteen cases (22%) exhibited both high- and low-affinity binding sites. A wide interpatient variability was observed for the site number, with physiologically-relevant high-affinity sites ranging from 7 to 310 fmol/mg protein in tumors and from 6 to 313 fmol/mg protein in normal mucosa. A significant positive correlation was demonstrated between tumor and normal mucosa for the high-affinity Kd values and for the number of high-affinity sites, suggesting a common regulation for both tumor and normal tissue.

INTERPRETATION

These observations (i) could explain recently-reported clinically-active EGFR targeting in colorectal tumors apparently negative for EGFR, and (ii) may offer a plausible explanation for the link observed between toxicity in normal tissue (cutaneous rash) and clinical outcome of patients treated with anti-EGFR drugs. Present data extends our understanding of EGFR identity in colorectal cancer which could be useful in reconsidering the predictive tools for the identification of tumors putatively responsive to EGFR targeted therapy.

Adjuvant therapy in colon cancer--what, when and how?

Bolus fluorouracil and leucovorin has been accepted as the standard adjuvant therapy in stage III colon cancer for many years. New drugs such as irinotecan, oxaliplatin and oral fluoropyrimidines have all completed phase III randomised evaluation in colon cancer. Several of these studies have been reported in the last 24 months. Oxaliplatin-based chemotherapy is now emerging as the new standard of care in adjuvant treatment of stage III colon cancer. The advent of monoclonal antibodies such as cetuximab and bevacizumab has further broadened the treatment horizon for colorectal cancer and they are the focus of the on-going randomised studies in adjuvant therapy of colon cancer. In stage II colon cancer, adjuvant treatment remains controversial and is not routinely recommended in all medically fit patients by the current American Society of Clinical Oncology guidelines, except several subsets including poorly differentiated histology, T4 lesions, bowel perforation presentation and inadequately sampled lymph nodes (<13). This review focuses on the relative merits of these agents, their safety, duration of treatment, timing of commencing treatment after surgery and the role of adjuvant therapy in stage II colon cancer, thereby assisting clinicians in deciding the optimal adjuvant treatment for patients in routine clinical practice.

Epidermal Growth Factor Receptor (EGFR) Inhibitors in Gastrointestinal Cancer

Gastrointestinal (GI) cancer continues to be a leading cause of cancer morbidity and mortality worldwide. Over the past decade the treatment options for patients with GI cancers have increased with the advent of newer combination chemotherapy regimes. Despite these clinical advances, new strategies are warranted in order to improve the efficacy as well as the safety. New molecular targets have provided novel opportunities in the treatment of GI cancer. One of the most advanced new approaches to date is the use of targeted inhibitors of the epidermal growth factor receptor (EGFR). In this review we describe the current status of therapeutic strategies based on EGFR inhibitors in the treatment of GI cancer.

Enhancement of antitumor activity of the anti-EGF receptor monoclonal antibody cetuximab/C225 by perifosine in PTEN-deficient cancer cells

Mutational inactivation or deletion of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN)/MMAC1/TEP gene in human cancer cells leads to a constitutively active status of the phosphatidylinositol 3-kinase/Akt pathway in the cells and has been linked to the lack of responses of the cells to the epidermal growth factor (EGF) receptor-targeted therapeutics. Akt is strongly inhibited by perifosine, an orally active alkyl-lysophospholipid currently being evaluated as an anti-cancer agent in phase 1 and 2 clinical trials. To determine whether perifosine may enhance the antitumor activity of the anti-EGF receptor monoclonal antibody cetuximab/C225 in PTEN-deficient cancer cells, we exposed MDA468 breast cancer cells (which contain mutated PTEN gene) and PC3 prostate cancer cells (in which the PTEN gene is deleted) to perifosine and cetuximab, alone and in combination. Treatment of the cells with perifosine reduced baseline levels of phosphorylated Akt, phosphorylated p44/42 mitogen-activated protein kinase (MAPK) and p38MAPK, and increased baseline levels of phosphorylated stress-activated protein kinase (SAPK)/c-jun NH(2)-terminal kinase (JNK). A 72-h exposure of the MDA468 and PC3 cells to perifosine alone resulted in cell death in a dose-dependent manner, which was enhanced by cetuximab. Addition of subtoxic doses of perifosine to cetuximab treatment also enhanced the cetuximab-induced growth inhibition. The combination treatment enhanced the inhibition of phosphorylation of Akt, p44/42MAPK and p38MAPK, but offset the phosphorylation of SAPK/JNK that was activated by perifosine treatment alone. Taken together, the data showed that perifosine enhances the antitumor activity of cetuximab in PTEN-deficient cancer cells. Further evaluation of the combination treatment in preclinical and clinical studies is warranted.

Simultaneous targeting of the epidermal growth factor receptor and cyclooxygenase-2 pathways for pancreatic cancer therapy

The aims of this study were to determine the effects of (a) combining the epidermal growth factor receptor (EGFR) blocker (erlotinib) and the cyclooxygenase-2 inhibitor (celecoxib) on cell growth and apoptosis in human pancreatic cancer cell lines, (b) baseline EGFR expression on the potentiation of erlotinib-induced apoptosis by celecoxib, and (c) the effects of the combination on the expression of the COX-2, EGFR, HER-2/neu, and nuclear factor-kappaB (NF-kappaB). Baseline expression of EGFR was determined by Western blot analysis in five human pancreatic cancer cell lines. BxPC-3, PANC-1, and HPAC had high EGFR and MIAPaCa had low EGFR. Cells were grown in culture and treated with erlotinib (1 and 10 micromol/L), celecoxib (1 and 10 micromol/L), and the combination. Growth inhibition was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was assayed by ELISA. Reverse transcriptase-PCR was used to evaluate COX-2 and EGFR mRNA. EGFR, COX-2, and HER-2/neu expression was determined by Western immunoblotting. Electrophoretic mobility shift assay was used to evaluate NF-kappaB activation. Growth inhibition and apoptosis were significantly (P < 0.05) higher in BxPC-3, HPAC, and PANC-1 cells treated with celecoxib and erlotinib than cells treated with either celecoxib or erlotinib. However, no potentiation in growth inhibition or apoptosis was observed in the MIAPaCa cell line with low expression of the EGFR. Significant down-regulation of COX-2 and EGFR expression was observed in the BxPC-3 and HPAC cells treated with the combination of erlotinib (1 micromol/L) and celecoxib (10 micromol/L) compared with celecoxib- or erlotinib-treated cells. Celecoxib significantly down-regulated HER-2/neu expression in BxPC-3 and HPAC cell lines. Significant inhibition of NF-kappaB activation was observed in BxPC-3 and HPAC cell lines treated with erlotinib and celecoxib. (a) Celecoxib can potentiate erlotinib-induced growth inhibition and apoptosis in pancreatic cell lines, (b) high baseline EGFR expression is a predictor of this potentiation, and (c) the down-regulation of EGFR, COX-2, and HER-2/neu expression and NF-kappaB inactivation contributes to the potentiation of erlotinib by celecoxib.

Chemotherapy and other systemic therapies for hepatocellular carcinoma and liver metastases

For hepatocellular carcinoma (HCC) that has advanced to the point that it is no longer amenable to local therapies, systemic therapy can be considered in select patients who have a good performance status. No systemic therapy has been clearly shown to improve overall survival compared with supportive care alone, although cancer-related symptoms can sometimes be palliated with therapy and some objective responses are seen. Systemic therapies for HCC include chemotherapy, both intravenous and infused via the hepatic artery, as well as hormonal therapy, immunotherapy, and targeted biologic agents. Colorectal, pancreatic, breast, and lung cancer are some of the most common tumors that metastasize to the liver. Response rates and effect on overall survival as a result of systemic therapy for liver metastases vary widely depending on primary tumor site. Targeted biologic agents are being integrated into standard treatment regimens for all of these cancer types, with variable effects on survival and other outcomes for all affected patients including those with liver metastases.

Chemo-immunotherapy of colorectal carcinoma: preclinical rationale and clinical experience

Advanced colorectal cancer is a common disease with an high mortality rate. For four decades, pharmacological treatment of the advanced disease was based on the use of 5-fluorouracil alone or in combination with biomodulators such as folinic acid and intereferon alpha. In the last 5 years, response to therapy has been considerably ameliorated thanks to the discovery of new drugs such as oxaliplatin and CPT-11. These agents, in combination with 5-fluorouracil, according to various schedules of treatment, have reached a significant improvement of palliation, response rate and survival. Immunotherapy is an uprising modality of treatment for human cancer including colorectal carcinoma. Its rationale is based on the knowledge that tumour cells are genetically unstable and produce molecular structures which allow their recognition and destruction by the immune-surveillance system. Therefore, humoral as well as cellular compartments of the immune system can be utilized according to a "passive" strategy (e.g. monoclonal antibody administration and adoptive immunotherapy) or an "active" approach, by using different modalities of vaccine therapy. In this context, monoclonal antibodies (mAbs) and cancer vaccines are being tested for the treatment of advanced colorectal cancer. Due to their genetic instability and extraordinary adaptative potential, tumour cells may acquire resistance to the immune effectors and mAbs exactly as they do for cytotoxic drugs. To improve the results of both immunological and chemical modality of cancer treatment, an increasing number of authors is starting to combine chemo and immunotherapy in the attempt to circumvent the limitations of both strategies. This report tries to review the possible rationale of the chemo-immunotherapy combination, illustrating preliminary results of preclinical and clinical studies.

Clinical Utility of Radiolabeled Monoclonal Antibodies in Prostate Cancer

Prostate cancer represents an ideal target for radioimmunotherapy based on the pattern of spread, including bone marrow and lymph nodes, sites that typically receive high levels of circulating antibody, and the small volume of disease, ideally suited for antibody delivery and antigen access. This review explores possible antibody targets in prostate cancer and focuses on the potential role for radioimmunotherapy by highlighting several clinical trials involving radiolabeled anti-prostate-specific membrane antigen monoclonal antibody J591. Prostate-specific membrane antigen, a highly prostate-restricted transmembrane glycoprotein with increased expression in high-grade, metastatic, and hormone-refractory disease, represents an ideal target for monoclonal antibody therapy in prostate cancer. Radiolabeled anti-prostate-specific membrane antigen monoclonal antibody J591 trials using the radiometals yttrium-90 and lutetium-177 have demonstrated manageable myelotoxicity, no significant nonhematologic toxicity, excellent targeting of soft-tissue and bone metastases, and preliminary efficacy including prostate-specific antigen and measurable disease responses. Additional studies are under way to better define the activity of radiolabeled antibody therapy as well as the role for fractionated therapy and combination approaches with taxane-based chemotherapy.

Cetuximab and irinotecan/5-fluorouracil/folinic acid is a safe combination for the first-line treatment of patients with epidermal growth factor receptor expressing metastatic colorectal carcinoma

BACKGROUND

To investigate the safety/tolerability of the EGFR-antibody cetuximab when added to irinotecan/5-fluorouracil (5-FU)/folinic acid (FA) for first-line treatment in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Twenty-one patients with untreated, metastatic, EGFR-expressing CRC received cetuximab 400 mg/m(2) as an initial dose, and thereafter 250 mg/m(2) weekly. In addition, patients received infusional 5-FU (24 h) in two dose levels (1500 mg/m(2), low 5-FU group, n = 6 or 2000 mg/m(2), high 5-FU group, n = 15), plus FA at 500 mg/m(2) and irinotecan at 80 mg/m(2), weekly x6 q50d.

RESULTS

Twenty patients were assessable for tolerability after the first cycle. There were no dose limiting toxicities (DLTs) in the low 5-FU group and three DLTs (20%) in the high 5-FU group (two patients with diarrhea grade 3 and one patient with diarrhea grade 4). In the low 5-FU group all six patients received >80% of the planned dose. In the high 5-FU group, seven of 14 patients (50%) received < or =80% of the planned chemotherapy dose during the first cycle due to dosage reductions whilst treatment delays occurred in 10/14 patients. During the whole study period, the common grade 3/4 adverse events were acne-like rash (38%) and diarrhea (29%). Chemotherapy did not affect the pharmacokinetics of cetuximab determined at weeks 1 and 4. Fourteen patients (67%, 95% CI 47% to 87%) had a confirmed response, and six (29%) had stable disease. Median time to progression was 9.9 months [lower 95% confidence limit (CL) 7.9, upper 95% CL not reached]. Median survival time was 33 months (lower CL 20, upper CL not reached). Four patients received secondary surgery with curative intent, and a fifth was potentially eligible for surgery but declined.

CONCLUSIONS

Addition of cetuximab to weekly infusional 5-FU/FA plus irinotecan is safe and first data suggest a promising activity. The 5-FU dose of 1500 mg/m(2) is recommended for further studies.

Efficacy and safety of cetuximab/irinotecan in chemotherapy-refractory metastatic colorectal adenocarcinomas: a clinical practice setting, multicenter experience

BACKGROUND

This study was designed to evaluate the efficacy and safety of irinotecan/cetuximab administered as third- or fourth-line therapy in a retrospective series of patients with metastatic colorectal cancer refractory to oxaliplatin and irinotecan.

PATIENTS AND METHODS

Most patients (90%) had been previously treated with adjuvant 5-fluorouracil/leucovorin, and all had received oxaliplatin-based regimens before receiving irinotecan-based second-line treatment. Sixty patients with irinotecan-refractory colorectal cancer received a regimen comprising weekly irinotecan 120 mg/m2 as a 1-hour intravenous infusion and cetuximab 400 mg/m2 infused over 2 hours as the initial dose and 250 mg/m2 infused over 1 hour for the subsequent administrations. A single treatment cycle comprised 4 weekly infusions followed by 2 weeks of rest.

RESULTS

According to an intent-to-treat analysis, a partial response was exhibited in 12 of 60 enrolled patients (20%; 95% confidence interval, 11%-32%) with a median duration of 5.1 months (range, 3-7.4 months). The tumor growth control rate was 50% (95% confidence interval, 37%-63%). Objective responses did not correlate with performance status, number of sites of disease, and pretreatments or epidermal growth factor receptor status. The median progression-free survival was 3.1 months (range, 1.2-9 months), whereas median overall survival was 6 months (range, 2-13 months). Both survival parameters correlated with performance status at the beginning of treatment. The main grade 3/4 toxicities were nausea (33%), diarrhea (27%), leukopenia (18%), asthenia (13%), and acne-like reaction (13%).

CONCLUSION

Our data suggest that the weekly irinotecan/cetuximab regimen is feasible in an outpatient setting and tolerated by most patients. At present, combinations of chemotherapy with cetuximab are being evaluated in patients with earlier-stage disease in a number of ongoing studies.

Prognostic Value of an Activation State Marker for Epidermal Growth Factor Receptor in Tissue Microarrays of Head and Neck Cancer

Overexpression and mutation of epidermal growth factor receptors (EGFR) have been shown to be important in the prognosis of several cancers, including head and neck cancers. However, our inability to define the activation status of these and other receptors limits our ability to assess the importance of these pathways and to exploit effectively new molecularly targeted treatments directed at their catalytic activities. Here we describe the use of automated, high-throughput fluorescence lifetime imaging microscopy to measure EGFR autophosphorylation status by fluorescence resonance energy transfer (FRET) in head and neck tumors. We have correlated FRET efficiency with the clinical and survival data. The results from head and neck arrays show that high FRET efficiency is correlated with worsening disease-free survival but not with overall survival. This powerful tool could be exploited as a new independent quantitative prognostic factor in clinical decisions and cancer management.

Novel toll-like receptor 9 agonist induces epidermal growth factor receptor (EGFR) inhibition and synergistic antitumor activity with EGFR inhibitors

PURPOSE

Immunostimulating Toll-like receptor 9 (TLR9) agonists cause antitumor activity interfering also with cancer proliferation and angiogenesis by mechanisms still incompletely understood. We hypothesized that modified TLR9 agonists could impair epidermal growth factor receptor (EGFR) signaling and, by this means, greatly enhance EGFR inhibitors effect, acting on both the receptor targeting and the immunologic arm.

EXPERIMENTAL DESIGN

We used a novel second-generation, modified, immunomodulatory TLR9 agonist (IMO), alone and in combination with the anti-EGFR monoclonal antibody cetuximab or tyrosine kinase inhibitor gefitinib, on the growth of GEO and cetuximab-resistant derivatives GEO-CR colon cancer xenografts. We have also evaluated the expression of several proteins critical for cell proliferation, apoptosis, and angiogenesis, including EGFR, mitogen-activated protein kinase, Akt, bcl-2, cyclooxygenase-2, vascular endothelial growth factor, and nuclear factor-kappaB.

RESULTS

IMO inhibited GEO growth and signaling by EGFR and the other proteins critical for cell proliferation and angiogenesis. IMO plus the anti-EGFR antibody cetuximab synergistically inhibited tumor growth, signaling proteins, and microvessel formation. EGFR signaling inhibition by IMO is relevant because IMO cooperated also with EGFR tyrosine kinase inhibitor gefitinib in GEO tumors, while it was inactive against GEO-CR xenografts. On the other hand, IMO boosted the non-EGFR-dependent cetuximab activity, causing a cooperative antitumor effect in GEO-CR cells. Finally, combination of IMO, cetuximab and chemotherapeutic irinotecan eradicated the tumors in 90% of mice.

CONCLUSION

IMO interferes with EGFR-related signaling and angiogenesis and has a synergistic antitumor effect with EGFR inhibitors, especially with cetuximab, boosting both the EGFR dependent and independent activity of this agent. Moreover, this therapeutic strategy could be translated in patients affected by colorectal cancer.