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

European Society for Medical Oncology 2006: meeting highlights on targeted therapies. Istanbul, Turkey, 29 September-3 October 2006

Considerable advances in our understanding of the complex cellular, molecular and genetic mechanisms underlying tumorigenesis over the last decade have contributed to the development of novel and improved targeted therapies in cancer intervention. These novel therapies interfere specifically with signaling pathways essential for tumor cell proliferation, survival and migration, they may be able to inhibit tumor growth and metastasis effectively, with fewer severe adverse events than seen with existing chemotherapeutic interventions, which have a narrow therapeutic index and are associated with severe toxic side effects. Among the most recent advances in anticancer treatments are therapies that target novel cellular entities, such as epidermal growth factor receptor and vascular endothelial growth factor. Monoclonal antibodies and protein tyrosine kinase inhibitors represent two classes among these promising new therapeutic interventions. During the European Society for Medical Oncology Congress 2006 (Istanbul, Turkey, 29 September-3 October) new and emerging biological therapies have represented a central argument of research. These highlights summarize the most interesting studies concerning molecular agents, such as panitumumab, lapatinib, sunitinib, sorafenib, erlotinib, bevacizumab and cetuximab, to provide a comprehensive overview of the important points and news about this area of research discussed during the meeting.

PTEN-Mediated Resistance to Epidermal Growth Factor Receptor Kinase Inhibitors

Molecularly targeted therapies are transforming the treatment of cancer. Elucidating the dynamic signaling networks that underlie sensitivity and resistance to these inhibitors is critical for successful clinical application. There is considerable evidence to suggest that constitutively activating mutations in kinases that regulate cellular growth may result in tumor cell "addiction" and favorable response to targeted inhibition. However, there is emerging evidence to suggest that clinical response may also be determined by other changes in the molecular circuitry of cancer cells, such as loss of key tumor-suppressor proteins. Here, we will discuss resistance to epidermal growth factor receptor tyrosine kinase inhibitors in glioblastoma patients that is mediated by loss of the PTEN tumor-suppressor protein.

Phase 1b Dose Escalation Study of Erlotinib in Combination with Infusional 5-Fluorouracil, Leucovorin, and Oxaliplatin in Patients with Advanced Solid Tumors

PURPOSE

Erlotinib (Tarceva) is a potent epidermal growth factor receptor (HER1) inhibitor. Infusional 5-fluorouracil (5-FU), leucovorin, and oxaliplatin (FOLFOX) is a standard therapy for colorectal cancer. This trial assessed the maximum tolerated dose (MTD), safety, preliminary efficacy, and pharmacokinetics of erlotinib combined with FOLFOX.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors were sequentially enrolled into three cohorts (cohort 1: 100 mg/d erlotinib, 65 mg/m(2) oxaliplatin, 200 mg/m(2) leucovorin, 400 mg/m(2) bolus 5-FU, and 400 mg/m(2) continuous infusion 5-FU; cohort 2: oxaliplatin increased to 85 mg/m(2) and 5-FU infusion increased to 600 mg/m(2); and cohort 3: erlotinib increased to 150 mg/d).

RESULTS

Thirty-two patients were enrolled (23 with colorectal cancer): no dose-limiting toxicities (DLT) were observed in cohort 1. In cohort 2, two of nine patients experienced a DLT (both diarrhea). In cohort 3, two of nine patients had a DLT (diarrhea and staphylococcal septicemia). Cohort 3 determined the MTD cohort and expanded to 17 patients in total. The most common adverse events were diarrhea, nausea, stomatitis, and rash (primarily mild/moderate). No pharmacokinetics interactions were observed. One patient (colorectal cancer) had a complete response, seven patients had a partial response, and nine had stable disease.

CONCLUSIONS

The MTD was defined as follows: 150 mg/d erlotinib, 85 mg/m(2) oxaliplatin; 200 mg/m(2) leucovorin, 400 mg/m(2) bolus 5-FU, and 600 mg/m(2) infusion 5-FU. At the MTD, the combination was well tolerated and showed antitumor activity, warranting further investigation in patients with advanced colorectal cancer and other solid tumors.

Cetuximab in the treatment of metastatic colorectal cancer

Cetuximab is a chimeric monoclonal antibody that binds to the epidermal growth factor receptor and thereby inhibits cell proliferation, metastasis and angiogenesis. Preclinical studies indicate that cetuximab induces synergistic antitumor activity when combined with chemotherapy or radiation. This observation is supported by clinical trials demonstrating that cetuximab improves tumor response when used in conjunction with modern chemotherapy in patients with metastatic colorectal cancer. Improved treatment efficacy may help to increase the rate of hepatic metastasis resection after downsizing of initially unresectable lesions. In pretreated patients, cetuximab may restore the sensitivity to irinotecan and, therefore, has been registered in this setting. Ongoing studies are investigating the integration of anti-epidermal growth factor receptor and anti-vascular endothelial growth factor strategies into new treatment regimens. Promising results have already been obtained in a trial combining irinotecan, bevacizumab and cetuximab.

Open-label phase II study evaluating the efficacy and safety of two doses of pertuzumab in castrate chemotherapy-naive patients with hormone-refractory prostate cancer

PURPOSE

To determine the prostate-specific antigen (PSA) 50% decline rate within 24 weeks of starting treatment with single-agent pertuzumab in castrate patients with hormone-refractory prostate cancer (HRPC).

PATIENTS AND METHODS

Two independent Simon's two-stage designs were used to evaluate two doses of pertuzumab administered intravenously once every 3 weeks. An interim analysis of the first 23 assessable patients in the first cohort treated at 420 mg (loading dose of 840 mg) allowed termination of additional enrollment if three patients had a 50% decline in PSA after all patients had completed at least three cycles of therapy or withdrew due to insufficient therapeutic response, death, or study-related toxicity before completing three cycles. A second cohort of patients treated at 1,050 mg could be enrolled with the same design, and if more than three patients had a 50% decline in PSA, 27 more patients would be treated at 1,050 mg.

RESULTS

Sixty-eight castrate, chemotherapy-naive men with HRPC were enrolled. A total of 35 patients were treated at 420 mg; no PSA declines 50% were observed at the interim analysis and recruitment was stopped. A total of 33 patients were then treated at 1,050 mg, and no PSA declines 50% were observed at the interim analysis. Pertuzumab was well tolerated.

CONCLUSION

Pertuzumab has no clinically significant single-agent activity in castrate patients with HRPC at either of the tested dose levels. This may reflect the continued presence of significant levels of intraprostatic androgen driving androgen receptor signaling.

Gefitinib and irinotecan in patients with fluoropyrimidine-refractory, irinotecan-naive advanced colorectal cancer: a phase I-II study

BACKGROUND

To establish the recommended dose level (RDL) and to evaluate the efficacy and safety of gefitinib plus irinotecan in patients with advanced fluoropyrimidine-refractory colorectal cancer (CRC).

PATIENTS AND METHODS

Patients with advanced CRC progressing on or within 12 weeks of fluoropyrimidine-based chemotherapy, irinotecan naive and performance status of two or less were recruited. During dose-finding phase, dose-limiting toxicity (DLT) was encountered at dose level 1, therefore subsequent dose de-escalation and pharmacokinetic (PK) studies were carried out. The RDL was then expanded in a multicentre setting to further evaluate safety and efficacy.

RESULTS

From June 2002 to February 2005, 39 patients were treated in total with 27 at the RDL. The RDL was established at irinotecan 225 mg/m(2) every 3 weeks and gefitinib 250 mg daily. The DLTs were neutropenia and diarrhoea. For the patients treated at RDL, the objective tumour response rate was 11.1% (95% confidence interval 2.4% to 29.2%) and median survival was 9.3 months. PK studies indicated that the addition of irinotecan to gefitinib resulted in an average of 50% increase in exposure to gefitinib (P < 0.05), but gefitinib did not alter the PK profiles of irinotecan or SN-38. Grade 3-4 toxic effects in all patients included diarrhoea (35.9%), lethargy (15.4%), neutropenia (15.4%), febrile neutropenia (10.3%) and skin rash (7.7%).

CONCLUSIONS

Irinotecan and gefitinib at this dose schedule was tolerable, but gefitinib did not appear to add substantial efficacy to irinotecan.

Long-term characteristics of 5-year survivors after liver resection for colorectal metastases

BACKGROUND

We investigated factors affecting 5-year survival in patients undergoing hepatic resection for colorectal cancer metastases, including events long after initial hepatectomy. Although retrospective studies have demonstrated survival benefit of hepatectomy for metastatic colorectal cancer, few have included sufficient 5-year survivors to identify survival-related factors throughout the clinical course.

METHODS

We divided 156 patients with hepatectomy for colorectal cancer metastases into 5-year survivors (n = 64) and patients dying before 5 years after hepatectomy (n = 92). Clinicopathologic data were compared retrospectively with respect to long-term outcome.

RESULTS

By multivariate analysis, large liver tumors (adjusted relative risk, 2.029; P = .011), short tumor doubling time (1.809; P = .026), and origin from poorly differentiated primary adenocarcinoma (12.632; P = .001) compromised survival, whereas initial treatment-related variables did not. Although no difference was seen in initial treatment-related variables between 5-year survivors with recurrence after hepatectomy and patients dying before 5 years, repeat surgery was used more frequently in survivors (P < .001), typically with adjuvant chemotherapy.

CONCLUSIONS

Reoperations for each recurrence of metastases, followed by additional chemotherapy, frequently resulted in long survival.

Mammalian target of rapamycin is activated in human gastric cancer and serves as a target for therapy in an experimental model

The mammalian target of rapamycin (mTOR) has become an interesting target for cancer therapy through its influence on oncogenic signals, which involve phosphatidylinositol-3-kinase and hypoxia-inducible factor-1alpha (HIF-1alpha). Since mTOR is an upstream regulator of HIF-1alpha, a key mediator of gastric cancer growth and angiogenesis, we investigated mTOR activation in human gastric adenocarcinoma specimens and determined whether rapamycin could inhibit gastric cancer growth in mice. Expression of phospho-mTOR was assessed by immunohistochemical analyses of human tissues. For in vitro studies, human gastric cancer cell lines were used to determine S6K1, 4E-BP-1 and HIF-1alpha activation and cancer cell motility upon rapamycin treatment. Effects of rapamycin on tumor growth and angiogenesis in vivo were assessed in both a subcutaneous tumor model and in an experimental model with orthotopically grown tumors. Mice received either rapamycin (0.5 mg/kg/day or 1.5 mg/kg/day) or diluent per intra-peritoneal injections. In addition, antiangiogenic effects were monitored in vivo using a dorsal-skin-fold chamber model. Immunohistochemical analyses showed strong expression of phospho-mTOR in 60% of intestinal- and 64% of diffuse-type human gastric adenocarcinomas. In vitro, rapamycin-treatment effectively blocked S6K1, 4E-BP-1 and HIF-1alpha activation, and significantly impaired tumor cell migration. In vivo, rapamycin-treatment led to significant inhibition of subcutaneous tumor growth, decreased CD31-positive vessel area and reduced tumor cell proliferation. Similar significant results were obtained in an orthotopic model of gastric cancer. In the dorsal-skin-fold chamber model, rapamycin-treatment significantly inhibited tumor vascularization in vivo. In conclusion, mTOR is frequently activated in human gastric cancer and represents a promising new molecular target for therapy.

Phase I study of gefitinib, irinotecan, 5-fluorouracil and leucovorin in patients with metastatic colorectal cancer

PURPOSE

To determine the maximum tolerated doses (MTD), toxicities, efficacy, and pharmacokinetics (PK) of gefitinib combined with irinotecan, 5-fluorouracil (5-FU) and leucovorin (IFL) in patients with previously untreated advanced colorectal cancer.

EXPERIMENTAL DESIGN

Starting doses were gefitinib 250 mg/day orally without interruption, irinotecan 100 mg/m(2) as a 90 min intravenous (i.v.) infusion, 5-FU 400 mg/m(2) bolus i.v. and leucovorin 20 mg/m(2) i.v. on days 1 and 8 of a 21-day cycle. Dose escalations involved increasing gefitinib to 500 mg then increasing irinotecan to 125 mg/m(2) and 5-FU to 500 mg/m(2).

RESULTS

Twenty-four patients received therapy. The starting doses proved to be the MTD, as attempts to increase the dose of either gefitinib or the chemotherapeutic agents resulted in dose-limiting toxicities. Gastrointestinal effects and bone marrow suppression were the principal toxicities; however, only 1/17 (6%) patients treated with the MTD had severe (grades 3-4) diarrhea and severe neutropenia occurred in only two (12%) patients. Partial responses occurred in 10/17 patients receiving the MTD and another five had stable disease. Median progression-free and overall survivals were 12.2 and 26.6 months, respectively. In ten patients treated with the MTD, the steady-state PK of gefitinib was not affected by IFL nor did gefitinib appear to influence the PK of either irinotecan or 5-FU.

CONCLUSIONS

Gefitinib can be safely combined with an intermittent weekly schedule of IFL. Evidence of promising activity should encourage further clinical evaluation of epidermal growth factor receptor tyrosine kinase inhibitors, such as gefitinib, combined with multiagent chemotherapy for metastatic colorectal cancer.

A phase I study of single administration of antibody-directed enzyme prodrug therapy with the recombinant anti-carcinoembryonic antigen antibody-enzyme fusion protein MFECP1 and a bis-iodo phenol mustard prodrug

PURPOSE

Antibody-directed enzyme prodrug therapy is a two-stage treatment whereby a tumor-targeted antibody-enzyme complex localizes in tumor for selective conversion of prodrug. The purpose of this study was to establish optimal variables for single administration of MFECP1, a recombinant antibody-enzyme fusion protein of an anti-carcinoembryonic antigen single-chain Fv antibody and the bacterial enzyme carboxypeptidase G2 followed by a bis-iodo phenol mustard prodrug. MFECP1 is manufactured in mannosylated form to facilitate normal tissue elimination.

EXPERIMENTAL DESIGN

Pharmacokinetic, biodistribution, and tumor localization studies were used to test the hypothesis that MFECP1 localizes in tumor and clears from normal tissue via the liver. Firstly, safety of MFECP1 and a blood concentration of MFECP1 that would avoid systemic prodrug activation were tested. Secondly, dose escalation of prodrug was done. Thirdly, the dose of MFECP1 and timing of prodrug administration were optimized.

RESULTS

MFECP1 was safe and well tolerated, cleared rapidly via the liver, and was less immunogenic than previously used products. Eighty-fold dose escalation from the starting dose of prodrug was carried out before dose-limiting toxicity occurred. Confirmation of the presence of enzyme in tumor and DNA interstrand cross-links indicating prodrug activation were obtained for the optimal dose and time point. A total of 28 of 31 patients was evaluable for response, the best response being a 10% reduction of tumor diameter, and 11 of 28 patients had stable disease.

CONCLUSIONS

Optimal conditions for effective therapy were established. A study testing repeat treatment is currently being undertaken.

Phase I/II study of preoperative cetuximab, capecitabine, and external beam radiotherapy in patients with rectal cancer

BACKGROUND

To assess the safety and preliminary efficacy of concurrent radiotherapy, capecitabine, and cetuximab in the preoperative treatment of patients with rectal cancer.

PATIENTS AND METHODS

Forty patients with rectal cancer (T3-T4, and/or N+, endorectal ultrasound) received preoperative radiotherapy (1.8 Gy, 5 days/week for 5 weeks, total dose 45 Gy, three-dimensional conformal technique) in combination with cetuximab [initial dose 400 mg/m(2) intravenous given 1 week before the beginning of radiation followed by 250 mg/m(2)/week for 5 weeks] and capecitabine for the duration of radiotherapy (650 mg/m(2) orally twice daily, first dose level; 825 mg/m(2) twice daily, second dose level).

RESULTS

Four and six patients were treated at the first and second dose level of capecitabine, respectively. No dose-limiting toxicity occurred. Thirty additional patients were treated with capecitabine at 825 mg/m(2) twice daily. The most frequent grade 1/2 side-effects were acneiform rash (87%), diarrhea (65%), and fatigue (57%). Grade 3 diarrhea was found in 15%. Three grade 4 toxic effects were recorded: one myocardial infarction, one pulmonary embolism, and one pulmonary infection with sepsis. Two patients (5%) had a pathological complete response.

CONCLUSIONS

Preoperative radiotherapy in combination with capecitabine and cetuximab is feasible with some patients achieving pathological downstaging.

Colorectal cancer

Cancers of the colon and rectum will affect 1 in 17 North Americans during their lifetime. The progress witnessed in the treatment of these cancers in recent years has been remarkable. Improvements have been realized in surgical technique, radiation therapy, and systemic therapies, particularly with the addition of oxaliplatin and irinotecan to the previously limited armamentarium of fluorouracil alone. Targeted therapies directed at the vascular endothelial growth factor pathway and the epidermal growth factor pathway are now key players in the treatment of colorectal cancer. With current-day therapies, more than 75% of patients with localized disease are recurrence free at 3 years, and up to 50% of patients with advanced unresectable disease are alive at 2 years. This review focuses on the evidence supporting the current role of chemotherapy and radiation therapy in the adjuvant management of colorectal cancers and the strategy of combining chemotherapy and biological therapy in the treatment of metastatic disease.

Biologic therapies: what and when?

Over the past two decades, major advances have been made in the understanding of the immune system and disease pathogenesis. This has coincided with the development of biologic therapies--monoclonal antibodies and fusion proteins. The decision of when to use such treatment in the clinic is not always straightforward. In addition to immune biology, the focus of this review will be on the application of these treatments to immune-mediated diseases and the molecular targets involved in pathogenesis, specifically those that have US Food and Drug Administration/European Medicines Agency approval. Brief comments will be made on biologics that have approval for non-immune disorders.

Adjuvant chemotherapy for colon cancer: evidence on improvement in survival

Clear progress has been made in the adjuvant treatment of colon cancer. Until very recently, the absolute benefit for survival obtained with the administration of 6 months' FU/LV compared with control was about 6%. Fluoropyrimidines have been shown to be at least as active and can replace intravenous FU/LV in stage III colon cancer. Based on the results of the MOSAIC and NSABP C-07 trials, the addition of oxaliplatin to FU/LV improves disease-free survival and FOLFOX for 6 months can be recommended as adjuvant treatment for patients with stage III colon cancer. The benefit of adjuvant chemotherapy in stage II disease is limited and it should be proposed in patients with high-risk features. Adjuvant treatment of colon cancer improving and the use of genetic/molecular markers with the new targeted therapies may further improve survival.

Cicatricial Ectropion Associated With Treatment of Metastatic Colorectal Cancer With Cetuximab

Cetuximab is a monoclonal antibody that binds to the epidermal growth factor receptor (EGFR) of cancer cells expressing EGFR and prevents dimerization and downstream cell signaling pathways. It has been shown to prolong survival in patients with metastatic colorectal cancer. Cutaneous toxicity is relatively common because of the inhibition of EGFR of normal epidermal cells. We present a 49-year-old man with metastatic colon cancer who had development of periocular skin toxicity, madarosis, and cicatricial ectropion after the addition of weekly cetuximab infusions to his baseline chemotherapy. His findings resolved within weeks of the discontinuation of the drug. Cicatricial ectropion is a potential sequela of EGFR inhibition by cetuximab and can resolve without surgical intervention with the discontinuation of this drug.

The Biology of Epidermal Growth Factor Receptor and its Value as a Prognostic/predictive Factor

Receptor tyrosine kinases play a major role in human carcinogenesis. Overexpression of the epidermal growth factor receptor (EGFR) has been associated with poor clinical outcome in several types of cancer. In principle, as with HER2, the EGFR status of a tumor should predict the likelihood of response to EGFR-targeted therapy. However, clinical data have failed to demonstrate a relationship between EGFR expression and response to the EGFR-targeted compounds cetuximab, gefitinib and erlotinib. Recently, patients reported to be EGFR negative have been shown to respond to cetuximab. Possible explanations include methodological failures or most likely heterogeneity and complexity of the mechanisms of EGFR-mediated molecular carcinogenesis. Immunohistochemistry is the most widely used method for measuring EGFR expression; however, its value is limited by lack of methodological standardization. Other approaches to measuring EGFR such as amplification assays are currently being introduced but need further testing before they can enter clinical practice. Mutational analysis seems also fruitful in predicting response to anti-EGFR small molecules. Further work is needed to identify how EGFR contributes to the carcinogenic and metastatic processes.

Point mutations of protein kinases and individualised cancer therapy

The treatment of cancer is rapidly changing, with an increasing focus on converting our improved understanding of the molecular basis of disease into clinical benefit for patients. Protein kinases that are mutated in cancer represent attractive targets, as they may result in cellular dependency on the mutant kinase or its associated pathway for survival, a condition known as 'oncogene addiction'. Early clinical experiences have demonstrated dramatic clinical benefit of targeting oncogenic mutations in diseases that have been largely resistant to traditional cytotoxic chemotherapy. Further, mutational activation of kinases can indicate which patients are likely to respond to targeted therapeutics. However, these experiences have also illuminated a number of critical challenges that will have to be addressed in the development of effective drugs across different cancers, to fully realise the potential of individualised molecular therapy. This review utilises examples of genetic activation of kinases to illustrate many of the lessons learned, as well as those yet to be implemented.

HER-2-Positive Breast Cancer

Therapeutic antibodies have shown great promise as targeted agents in the treatment of patients with cancer. Trastuzumab, a humanized monoclonal antibody targeting human epidermal growth factor receptor-2 (HER-2), is of special importance in breast cancers overexpressing HER-2. Such rationally designed substances bind to cancer cells expressing the targeted antigen and, by various mechanisms, lead to tumor cell degradation. Only one-third of patients, however, initially respond to trastuzumab monotherapy and the majority of initial responders demonstrate disease progression within 1 year of treatment initiation. Therefore, alternative compounds targeting the HER-2 receptor or downstream signaling pathways are of great importance. Lapatinib is a tyrosine kinase inhibitor, blocking tryosine kinase domains of both epidermal growth factor receptor and HER-2. This substance holds promise for the treatment of cancer after trastuzumab failure, and might be active in cerebral metastases. Other strategies in trastuzumab-resistant disease include bispecific antibodies (which bind to HER-2 and Fc receptors, thereby directing immune cells towards the tumor), the combination of antibodies, or targeting tumor vessel growth by blocking vascular endothelial growth factor (VEGF) or VEGF receptors. Heat shock protein 90, a chaperone protein that controls the folding of HER-2, also represents a potential target. Multi-targeted kinase inhibitors such as sunitinib or sortenib are already established in renal cell cancer. These compounds are currently being evaluated in breast cancer and might represent interesting options both in HER-2-positive and -negative disease. In conclusion, trastuzumab remains the gold standard in HER-2-positive breast cancer therapy. However, in trastuzumab-resistant disease, new strategies and compounds are currently under evaluation.

Cost considerations in the treatment of colorectal cancer

Colorectal cancer is among the most common malignancies in developed countries. Screening can reduce mortality significantly, although the most appropriate method is still under debate. Observational studies have revealed that lifestyle measures may also be beneficial for prevention of colorectal cancer. Surgery is still the most effective treatment modality for colorectal cancer. The survival benefits of chemotherapy are only modest. For nearly 5 decades, 5-fluorouracil (5-FU) has been the main cytotoxic agent for treatment of colorectal cancer. In the last decade, the new cytotoxic agents raltitrexed, irinotecan and oxaliplatin have been introduced, next to the oral 5-FU analogues capecitabine and tegafur in combination with uracil (UFT). Moreover, the immunotherapeutics bevacizumab and cetuximab have become approved for treatment of metastatic colorectal cancer. The economic implications of colorectal cancer treatment are substantial. The costs of treatment are mainly attributable to the early and terminal stage of the disease (i.e. surgery, hospitalisation, chemo- and immunotherapy and supportive care). The introduction of new chemo- and immunotherapeutics has caused a continuing increase of treatment expenditures. Therefore, comparative costs and cost effectiveness are important for assessing the value of new treatment regimens. The available study results suggest that addition of irinotecan or oxaliplatin to 5-FU/folinic acid dosage regimens is cost effective. Also, capecitabine is calculated to be cost effective when compared with 5-FU/folinic acid. For UFT, no comparative studies of cost effectiveness were found. Since raltitrexed and 5-FU/folinic acid have shown equal efficacy in terms of survival, cost-effectiveness analysis is considered not to be applicable and cost-minimisation analysis may be sufficient. At present, pharmacoeconomic analyses of combination treatment with the immunotherapeutics bevacizumab or cetuximab are not available, except for recent cost-effectiveness considerations by the UK National Institute for Health and Clinical Excellence with negative recommendations for both agents in the treatment of metastatic colorectal cancer. Given the high treatment costs, substantial toxicity and relatively limited efficacy of the fast changing chemo- and immunotherapeutic combinations for colorectal cancer, examination of cost-effectiveness studies should be conducted on a routine basis along with determination of clinical benefits.

Results from an in vitro and a clinical/pharmacological phase I study with the combination irinotecan and sorafenib

PURPOSE

This single-centre, open-label, phase I dose-escalation study was performed to investigate the safety, pharmacokinetics (PK) and efficacy of sorafenib, a multi-kinase inhibitor, combined with irinotecan, a cytotoxic agent, in patients with advanced, refractory solid tumours.

PATIENTS AND METHODS

In an initial dose-escalation phase, patients received irinotecan 125 mg/m(2) and sorafenib 100, 200 and 400 mg twice daily (bid) (cohorts 1-3). In an extended phase, colorectal cancer (CRC) patients received fixed-dose irinotecan 140 mg and sorafenib 400 mg bid (cohort 4).

RESULTS

Thirty-four patients were treated: 20 in the dose-escalation phase (common tumour types: CRC [45%], ovarian [5%], pancreatic [5%]) and 14 patients in the CRC extension. Frequent drug-related adverse events were gastrointestinal symptoms, dermatological reactions and constitutional symptoms. The maximum tolerated dose was not reached. Generally, concomitant administration of irinotecan had no impact on the PK of sorafenib. Sorafenib 100 or 200 mg bid had no impact on the PK of irinotecan or its metabolite SN38. In contrast, sorafenib 400 mg bid significantly increased irinotecan and SN38 exposures; however, this was not associated with increased toxicities. Stable disease was achieved in 12/20 (60%) evaluable patients in cohorts 1-3, and 10/13 (77%) evaluable patients in cohort 4. A further patient from cohort 4 had a partial response of >200 days. The increase of SN38 exposure might be due to inhibition of formation of the SN38 glucuronide by sorafenib. In vitro, sorafenib strongly inhibited SN38 glucuronidation in human liver microsomes as indicated by a K(i) value of 2.7 micromol/l.

CONCLUSION

Sorafenib 400 mg bid can be combined with irinotecan 125 mg/m(2) or 140 mg for the treatment of patients with advanced, refractory solid tumours, although monitoring for toxicity is recommended.

Cetuximab: appraisal of a novel drug against colorectal cancer

Cetuximab (C225, Erbitux, Merck, Darmstadt, Germany) is a human-mouse chimeric therapeutic monoclonal antibody (mAb) that competitively binds to the extracellular domain of the human epidermal growth-factor receptor (EGFR). It has been developed out of the murine antibody M225 "from bench to bedside" in less than two decades, and is the anti-EGFR mAb furthest ahead in clinical evaluation. In Europe, cetuximab is approved for the treatment of patients with EGFR-expressing, metastatic colorectal cancer after failure of treatment with irinotecan since 2004, and for the treatment of patients with locally advanced squamous cell cancer of the head and neck concomitant to radiotherapy since 2006. We here summarize the current role of cetuximab in the treatment of colorectal cancer, give an overview on the ongoing studies, address the most important controversies, and point out the chances and challenges for the future use of cetuximab in colorectal cancer and other human malignancies.

Anti-EGFR and ErbB-2 antibodies attenuate cyclooxygenase-2 expression and cooperatively inhibit survival of human colon cancer cells

Cyclooxygenase-2 (COX-2) is a transcriptional target and downstream effector of the ErbB-1 (EGFR) and ErbB-2 signaling pathways. We found that anti-EGFR and anti-ErbB-2 antibodies inhibited ERK phosphorylation and downregulated COX-2 protein expression in HCA-7 human colon carcinoma cells. Both antibodies also augmented the cytotoxic effects of the selective COX-2 inhibitor, NS-398. Inhibition of EGFR and ErbB-2 attenuated cell growth by increasing cell death, and the antibody combination suppressed cell growth to a greater extent than did either antibody alone. In conclusion, EGFR and ErbB-2 regulate ERK-mediated COX-2 expression and their selective inhibition enhanced NS-398-induced cell death. Cooperative inhibition of cell growth by EGFR and ErbB-2 blockade suggests the therapeutic potential of targeting multiple ErbB receptors.

Phase II trial of cetuximab in patients with previously treated non-small-cell lung cancer

PURPOSE

To determine the efficacy of cetuximab in patients with recurrent or progressive non-small-cell lung cancer (NSCLC) after receiving at least one prior chemotherapy regimen.

PATIENTS AND METHODS

This was an open-label, phase II study of patients with epidermal growth factor receptor (EGFR) -positive and EGFR-negative advanced NSCLC with Eastern Cooperative Oncology Group performance status 0 to 1. Patients received cetuximab 400 mg/m2 intravenously (IV) during 120 minutes on week 1 followed by weekly doses of cetuximab 250 mg/m2 IV during 60 minutes. A cycle was considered as 4 weeks of treatment and therapy was continued until disease progression or intolerable toxicities. The primary end point was to assess response rate. Secondary end points included an estimation of time to progression and survival.

RESULTS

Patient and disease characteristics (n = 66) included EGFR-positive status (n = 60); EGFR-negative status (n = 6); number of prior regimens (one, n = 28; two, n = 27; > or = three, n = 11); male (n = 41); female (n = 25); adenocarcinoma (n = 36); and smoking status (never, n = 13; former, n = 45; current, n = 8). Grade 3/4 toxicities included acne-like rash (6.1%), anaphylactic reactions (1.5%), and diarrhea (1.5%). The response rate for all patients (n = 66) was 4.5% (95% CI, 0.9% to 12.7%) and the stable disease rate was 30.3% (95% CI, 19.6% to 42.9%). The response rate for patients with EGFR-positive tumors (n = 60) was 5% (95% CI, 1.0% to 13.9%). The median time to progression for all patients was 2.3 months (95% CI, 2.1 to 2.6 months) and median survival time was 8.9 months (95% CI, 6.2 to 12.6 months).

CONCLUSION

Although the response rate with single-agent cetuximab in this heavily pretreated patient population with advanced NSCLC was only 4.5%, the disease control rates and overall survival seem comparable to that of pemetrexed, docetaxel, and erlotinib in similar groups of patients.

Molecular mechanisms of epidermal growth factor receptor (EGFR) activation and response to gefitinib and other EGFR-targeting drugs

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases, including EGFR, HER2/erbB2, and HER3/erbB3, is an attractive target for antitumor strategies. Aberrant EGFR signaling is correlated with progression of various malignancies, and somatic tyrosine kinase domain mutations in the EGFR gene have been discovered in patients with non-small cell lung cancer responding to EGFR-targeting small molecular agents, such as gefitinib and erlotinib. EGFR overexpression is thought to be the principal mechanism of activation in various malignant tumors. Moreover, an increased EGFR copy number is associated with improved survival in non-small cell lung cancer patients, suggesting that increased expression of mutant and/or wild-type EGFR molecules could be molecular determinants of responses to gefitinib. However, as EGFR mutations and/or gene gains are not observed in all patients who respond partially to treatment, alternative mechanisms might confer sensitivity to EGFR-targeting agents. Preclinical studies showed that sensitivity to EGFR tyrosine kinase inhibitors depends on how closely cell survival and growth signalings are coupled with EGFR, and also with HER2 and HER3, in each cancer. This review also describes a possible association between EGFR phosphorylation and drug sensitivity in cancer cells, as well as discussing the antiangiogenic effect of gefitinib in association with EGFR activation and phosphatidylinositol 3-kinase/Akt activation in vascular endothelial cells.

Epidermal Growth Factor Receptor Activation: How Exon 19 and 21 Mutations Changed Our Understanding of the Pathway

The discovery of epidermal growth factor receptor (EGFR) mutations in never-smokers has been the most relevant finding ever in non–small cell lung cancer. When patients whose tumors bear the sensitizing mutations are treated with the tyrosine kinase inhibitors gefitinib or erlotinib, we witness response rates and durations never before reported, including complete responses. At the same time, the presence of EGFR mutations has raised numerous new questions, tantalizing data, and new challenges for treatment. This is particularly true as we try to generalize the findings in lung cancer to other malignancies. The indiscriminate use of gefitinib or erlotinib in the general lung cancer population results in meager survival benefit for patients. Similarly, the tyrosine kinase inhibitors have limited activity in a variety of tumor types with EGFR overexpression. This has led to the question of whether EGFR remains a viable target in patients other than those whose tumors contain mutations, and whether the modest activity of cetuximab in colorectal cancer and head and neck cancer represents all that we can expect from inhibition of this pathway in the absence of mutation. Mechanisms of pathway activation other than mutation have been discovered in recent years, and include overexpression mediated by gene amplification or by amplification of a dinucleotide repeat in the EGFR promoter, mutation of an extracellular region on EGFR generating a mutant protein termed EGFRvIII, and enhanced signaling due to heterodimerization with other members of the EGFR family, particularly overexpression of HER2/HER3. The extent to which these paths to EGFR activation will confer sensitivity to the tyrosine kinase inhibitors or to EGFR monoclonal antibodies is being explored. Thus far, published clinical data suggest that there is little room for the administration of gefitinib or erlotinib in the absence of EGFR mutations. The five articles in this edition of CCR Focus will address the various mechanisms of EGFR pathway activation and provide insight into the potential for translation into clinical relevance.

Recent developments in colorectal cancer treatment by monoclonal antibodies

A growing understanding of the molecular mechanisms involved in cancer biology and continuous refinement of available technologies for drug discovery have prompted the development of new therapeutic tools targeting specific cancer-associated molecular pathways. Among these so-called biological therapies, monoclonal antibodies have now reached the time of clinical application. Besides initial development of the murine antibody edrecolomab, the impact of monoclonal antibodies on cancer therapy has recently been clearly demonstrated in colorectal cancer by targeting two major pathways critical to tumourigenesis: the epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) signalling pathways. These antibodies showed significant clinical activity in advanced colorectal cancer, especially when combined with chemotherapy. This paper reviews the status of the monoclonal chimeric antibody cetuximab (Erbitux) and other anti-EGFR antibodies, and of bevacizumab (Avastin; an anti-VEGF humanised monoclonal antibody), in colorectal cancer treatment.

Combining siRNAs at two different sites in the EGFR to suppress its expression, induce apoptosis, and enhance 5-fluorouracil sensitivity of colon cancer cells

BACKGROUND

The epidermal growth factor receptor (EGFR) has played an important role in the growth and apoptosis of colon cancer. The RNA interference (RNAi) technique can suppress gene expression, but the effects of double combining sites RNAi targeting EGFR have not been well understood.

METHODS

pU6-EGFR-shRNA-1 and pU6-EGFR-shRNA-2 expressive vectors were transfected to the LoVo cells. Five groups were selected for the study: Group 1, the control cells; group 2, the negative control plasmid vector HK; group 3, pU6-EGFR-shRNA-1; group 4, pU6-EGFR-shRNA-2; group 5, pU6-EGFR-shRNA-1 and pU6-EGFR-shRNA-2, half for each. The mRNA and protein expression were assessed by Real Time quantitative PCR and Western blot. Apoptosis was determined via flow cytometry. IC(50) and the inhibition ratio of 5-fluorouracil (5-FU) were carried out by CCK-8.

RESULTS

In groups 3, 4, and 5, the mRNA expression was decreased by (80.22 +/- 3.42)%, (81.30 +/- 2.83)%, and (90.58 +/- 2.76)%, respectively, and the protein expression was decreased by (74.11 +/- 4.02)%, (73.39 +/- 2.30)%, and (90.39 +/- 3.34)%, respectively. Meanwhile, the cell apoptosis increased by (10.43 +/- 0.49)%, (10.13 +/- 0.39)%, and (14.17 +/- 0.53)%, respectively. The IC(50) of 5-FU and cell inhibition ratio analysis demonstrated that there were significant differences between the following three: group 5, groups 3 and 4, and groups 1 and 2.

CONCLUSIONS

Both pU6-EGFR-shRNA-1 and pU6-EGFR-shRNA-2 are capable of suppressing EGFR expression of the LoVo cell and can promote apoptosis and increase the cell toxicity of 5-FU. The double combining sites RNAi technique is significantly better than a single site.

Lack of usefulness of epidermal growth factor receptor expression determination for cetuximab therapy in patients with colorectal cancer

In patients with metastatic colorectal cancer, the use of cetuximab currently requires a documented tumoral epidermal growth factor receptor positivity. Responses to cetuximab, however, have been described in patients with epidermal growth factor receptor-negative tumors. We have used cetuximab in all eligible patients with metastatic colorectal cancer, whether their tumor expressed epidermal growth factor receptor or not. We assessed the cetuximab efficacy with regard to tumoral epidermal growth factor receptor expression. Twenty patients with metastatic colorectal cancer were treated off study with cetuximab and irinotecan after failure of oxaliplatin- and irinotecan-based regimens. Tumors were analyzed in all patients for epidermal growth factor receptor expression by immunohistochemistry. Tumors were positive for epidermal growth factor receptor in 12 cases and negative in eight cases. An objective response to cetuximab-based therapy was obtained in four patients (20%). Tumors of these four patients were negative for epidermal growth factor receptor expression. These results provide further evidence for the lack of usefulness of epidermal growth factor receptor detection by immunohistochemistry for cetuximab therapy in patients with metastatic colorectal cancer.

Is EGFR expression altered following postoperative chemotherapy for colorectal adenocarcinoma?

Background

There is immunohistochemical evidence to suggest that expression of epidermal growth factor receptor (EGFR) in primary colorectal adenocarcinoma predicts its expression in recurrent disease. This study investigates whether postoperative chemotherapy affects the degree of concordance between EGFR statuses of the two tumors.

Methods

Thirty-three patients were identified from the files of Sunnybrook Health Sciences Center from July 1994 to June 2005. All patients had resection of their primary tumors and their distant recurrences. Eighteen patients received postoperative chemotherapy, 3 of which also received postoperative radiation therapy. Representative primary and recurrent tumor sections were stained using mouse anti-EGFR antibodies and only membranous staining of malignant cells was recorded. Results were reported as negative (no staining), 1+ (positivity in <50% of cells) or 2+ (positivity in >50% of cells).

Results

EGFR immunostaining in the 15 patients, who received no postoperative chemotherapy, was decreased in 3 recurrences, remained the same in 10 and increased in 2. In the group of 18 patients who received postoperative chemotherapy, EGFR immunostaining was decreased in 6 recurrences, remained the same in 9 and increased in 3 (p = 0.6598). In patients who received postoperative chemotherapy, the odds ratio for a recurrence to show lower levels of EGFR immunostaining compared to its originally resected primary was 4.75 (CI = 0.94 – 26.73).

Conclusion

These preliminary data suggest that recurrences following postoperative chemotherapy are likely to have lower levels of EGFR expression compared to cases who receive no chemotherapy. Although the difference of immunostaining profiles between the two groups was not statistically significant, this observation might impact the management of these patients by targeted biologic therapies and its practical implications need further validation in larger series.

Gefitinib in combination with 5-fluorouracil (5-FU)/folinic acid and irinotecan in patients with 5-FU/oxaliplatin- refractory colorectal cancer: a phase I/II study of the Arbeitsgemeinschaft für Internistische Onkologie (AIO)

BACKGROUND

Gefitinib is an epidermal growth factor receptor tyrosine kinase inhibitor. It potentiates cytotoxic drug activity in human xenografts. This phase I/II dose-finding study evaluated gefitinib in combination with a 5-fluorouracil (5-FU)/folinic acid (FA)/irinotecan (FOLFIRI-AIO) regimen in patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Patients received gefitinib 250 mg per day, and escalating doses of FOLFIRI-AIO i.v. (dose level (DL) 1: 1600/ 500/60 mg/m(2); DL2: 1600/500/80 mg/m(2); DL3: 2000/500/ 80 mg/m(2)) weekly x 6. Dose-limiting toxicity (DLT) was determined in patients who completed 1 cycle of therapy.

RESULTS

13 patients were enrolled. 1 out of 6 patients on DL1 exhibited DLT (acute psychosis), and a total of 7 patients received DL2. Of those, 3 patients had DLT during cycle 1 (nausea/vomiting n = 2; diarrhea n = 1, fatigue n = 2). Recruitment was stopped at this DL because of the unfavorable toxicity profile observed during the first and subsequent treatment cycles (out of 7 patients: nausea/vomiting grade 3 n = 2, diarrhea grade 3 n = 2; fatigue n = 3). Only 1 patient showed a partial remission, and 2 patients experienced stabilization of disease.

CONCLUSIONS

Dose escalation had to be stopped early because of gastrointestinal toxicity and fatigue. This treatment regimen did not seem advantageous with respect to efficacy in comparison with FOLFIRIAIO alone.

Effectiveness of cetuximab/gefitinib in the therapy of a sacral chordoma

BACKGROUND

Chordomas are rare tumors of the skull base and the spine. Treatment is difficult since conventional radiotherapy or chemotherapy have only limited effects.

PATIENT AND METHODS

A patient with a sacral chordoma and pulmonary metastases received initial surgery and radiotherapy for a local recurrence. After 11 months another local recurrence as well as a progression of the pulmonary metastases was documented. As tumor biopsies revealed the expression of the EGF receptor an individual treatment approach with a combination of cetuximab and gefitinib was performed.

RESULTS

Under the treatment with cetuximab/gefitinib the local recurrence and the pulmonary metastases showed a partial response over the follow-up period of 9 months. To date no treatment failure was observed.

CONCLUSIONS

The inhibition of the EGF pathway seems to be an effective measure in the treatment of a chordoma. Further follow-up will have to prove the long-term efficiency.

Mechanisms of disease: Oncogene addiction--a rationale for molecular targeting in cancer therapy

There has been considerable progress in the systemic treatment of cancer because of the rapid development and clinical application of molecular targeted agents. Although patients with a particular type and stage of cancer are often treated as a single group, more-specific therapy is being considered, as subsets of these patients who are more likely to benefit from treatment with particular agents are being identified. We previously introduced the concept of 'oncogene addiction' to explain how some cancers that contain multiple genetic, epigenetic, and chromosomal abnormalities are dependent on or 'addicted' to one or a few genes for both maintenance of the malignant phenotype and cell survival. Thus, reversal of only one or a few of these abnormalities can inhibit cancer cell growth and in some cases translate to improved survival rates. This review summarizes current experimental and clinical evidence for the concept of oncogene addiction and describes molecular mechanisms that may explain this phenomenon. In addition, we discuss how high-throughput screening methods, including gene-expression profiling and proteomics, and emerging methods for analyzing complex cellular networks can be used to identify the state of oncogene addiction, i.e. the 'Achilles' heel,' in specific cancers. Finally, we discuss the use of molecular targeted agents in combination with other anticancer agents as a strategy to optimize therapy and prevent disease recurrence.

Long-term survival of patients downstaged by oxaliplatin and 5-fluorouracil combination followed by rescue surgery for unresectable colorectal liver metastases

OBJECTIVES

To evaluate long-term survival of patients resected for primarily unresectable colorectal liver metastases downstaged by systemic chemotherapy.

METHODS

Among a group of 82 patients with advanced colorectal cancer, 39 had unresectable liver metastases. After treatment with systemic 3-weekly 5FU/folinic acid/oxaliplatin chemotherapy, the outcome of 11 patients made resectable thanks to chemotherapy was compared to that of 28 patients who were not. Criteria for non-resectability consisted of diffuse bilobar invasion with inability to achieve complete resection, unilobar or bilobar invasion plus vascular extension (invasion of inferior vena cava or 2 supra-hepatic veins plus continuity with the 3rd) or involvment of hepatic pedicle. Before and after surgery, CT scan evaluation was performed every 2 months. Progression free survival was defined as the time between starting chemotherapy and recurrence of the disease. We used Kaplan-Meier survival curves and log-rank test for comparisons, P values were two-sided and considered significant if<0.05.

RESULTS

Progression free survival times were 14 and 6 months, median overall survival were 60 and 18.5 months, respectively, in favour of secondary resected subjects.

CONCLUSION

Considering the magnitude of the survival benefit, one may question the need and feasibility for trials to assess more formally the impact of surgery in that setting.

Chemotherapeutic agents for colorectal cancer with a defective mismatch repair system: The state of the art

Mismatch repair (MMR) proteins are capable of recognizing and processing not only single base-pair mismatches and insertion-deletion loops that occur during DNA replication, but also adducts in DNA resulting from treatment with cancer chemotherapy agents. MMR deficiency leads to microsatellite instability (MSI) and results in resistance to antimetabolites, alkylating and platinating agents, DNA minor groove binders, and inhibitors of topoisomerases. Therefore, anticancer agents that can be recommended for use in MMR deficient colorectal cancers are those that exert their cytotoxicity regardless of the MMR status. These include some alkylating drugs, brostacillin, gemcytabine, photodynamic therapy, taxanes. An approach that is currently receiving much attention is the use of agents such as 5-azacytidine, an inhibitor of the DNA methyltransferases, in combination with inhibitors of histone de-acetylation, to restore the MMR function. A strong anti-proliferative efficacy with a relatively low direct cytotoxicity, obtainable with oloumicine and roscovitine (selective cyclin-dependent kinases inhibitors) can represent a new expedient for the therapeutic treatment of MMR deficient colorectal cancers. The question of how MMR defects modulate the response to chemotherapeutics deserves further investigation, to enable a more aware choice of cancer treatment.

Predictive and prognostic molecular markers in outcome of esophageal cancer

Despite improvements in detection, surgical resection and (neo-) adjuvant therapy, the overall survival in esophageal cancer remains lower than in other solid tumors. In fact, less than 20% of patients with advanced esophageal cancer benefit from a neoadjuvant therapy. Therefore predictive/prognostic markers are needed to allow tailored (radio-) chemotherapy with increased efficacy and decreased toxicity. Recently potential predictive/prognostic factors have been characterized by innovative molecular-based technologies. These factors include growth-factor receptors, enzymes of angiogenesis, tumor suppressor genes, cell cycle regulators, enzymes involved in the DNA repair system, in apoptosis and in the degradation of extracellular matrix. The results of these mostly retrospective studies are promising but prospective studies are needed to validate those markers in the multimodal therapy of esophageal cancer.

Conformal Radiotherapy of the Dominant Liver Metastasis

OBJECTIVES

To evaluate the safety and efficacy of conformal radiotherapy (RT) of the dominant liver metastasis as palliative treatment of patients with unresectable colorectal cancer liver metastases.

METHODS

We retrospectively reviewed the hospital and RT records of 17 patients with unresectable colorectal liver metastases who had been treated with palliative RT to the dominant liver metastasis at our institution.

RESULTS

The median size of the dominant liver metastasis was 10 cm (range, 3-19 cm). Twelve patients (71%) had evidence of extrahepatic disease. A median of 2 (range, 0-4) prior chemotherapy regimens had been administered. Median radiation dose was 42 Gy (range, 7.5-72 Gy). Concurrent chemotherapy included celecoxib in 1 (6%), capecitabine in 6 (35%), and both agents in 9 (53%) patients. Frequencies of acute diarrhea, nausea, vomiting, fatigue, hand-foot syndrome, and neutropenia were 29%, 47%, 6%, 29%, 7%, and 0%, respectively (all grade 2 or lower; no grade 3 toxicities). No late toxicities were noted. With a median follow-up time of 9.2 months, the median actuarial overall survival time from RT was 12.6 months (95% confidence interval [CI]: 3.3-40.9 months). The actuarial in-field local control rate was 62% at 6 months. The median actuarial time to in-field, out-of-field hepatic and distant progression were 6.8, 3.9, and 4.1 month, respectively (95% CIs, 3.9-15.8, 1.8-6.3, and 1.8-11.5 months, respectively).

CONCLUSIONS

Conformal RT to the dominant liver metastasis as palliative therapy for unresectable colorectal cancer liver metastases has an acceptable toxicity profile and may improve survival. This approach merits further exploration.

Perspectives for targeted therapies in cancer of unknown primary site

Cancer of unknown primary site (CUP) ranks as the fourth most common cause of cancer deaths. Regression of the primary, early development of systemic metastases and resistance to therapy are hallmarks of this heterogeneous clinical entity. Targeted therapy offers promise for improvement of outcome of such patients, but it is currently hindered by lack of known molecular targets on which tumours are dependent for growth. In this review, we present the gene and protein profiling studies done on expression of oncogenes, tumour-suppressor genes and angiogenesis effectors and discuss the therapeutic potential of developed targeted agents. Existing data show occasional overexpression of Ras, BCL2 oncoproteins, absence of active EGFR/c-KIT/PDGFR signalling, uncommon presence of tumour-suppressor gene mutations and highly active angiogenesis in CUP. High-throughput multi-gene, multi-protein platforms offer promise for unravelling the complex molecular pathophysiology of CUP, for identification of targets suitable for modulation and ultimately hope for abrogation of its aggressive natural history.

Cutaneous side effects of epidermal growth factor receptor inhibitors: clinical presentation, pathogenesis, and management

The growing investigation and use of epidermal growth factor receptor (EGFR) inhibitors in anticancer therapy has been motivated by their specificity for EGFR, which improves their ability to target cancer cells and enhances their safety profile compared with many other conventional chemotherapeutic agents. However, their growing use has been accompanied by an increasing incidence of cutaneous toxicities, which can cause serious discomfort and be disabling. This review illustrates the common cutaneous side effects seen in patients receiving EGFR inhibitors and discusses various options for management. With effective management of these side effects, dermatologists can play an integral role in facilitating compliance with anti-EGFR therapy and aid with effective oncologic management.

A phase II trial of EMD72000 (matuzumab), a humanized anti-EGFR monoclonal antibody, in patients with platinum-resistant ovarian and primary peritoneal malignancies

OBJECTIVE

The primary objective of this study was to determine the rate of response to matuzumab in patients with recurrent, EGFR-positive ovarian, or primary peritoneal cancer. Secondary end points included safety and tolerability, time to tumor progression, duration of response, and overall survival.

METHODS

A multi-institutional single arm phase II trial.

RESULTS

Of 75 women screened for the study, 37 were enrolled and treated. Median age of the treated patient population was 58 years, and most patients had more than four prior lines of chemotherapy. Therapy was well tolerated, the most common toxicities being a constellation of skin toxicities, including rash, acne, dry skin, and paronychia, as well as headache, fatigue, and diarrhea. Serious adverse events were very rare but included a single episode of pancreatitis that may have been drug related. All patients completed therapy, receiving 1 to 30 infusions of matuzumab. There were no formal responses (RR=0%, 95% CI: 0-9.5%), although 7 patients (21%) were on therapy for more than 3 months with stable disease.

CONCLUSIONS

Matuzumab at the dose and schedule selected is well tolerated. In this population of very heavily pretreated patients with epithelial ovarian and primary peritoneal malignancies, there was no evidence of significant clinical activity when matuzumab was administered as monotherapy.

Ocular toxicity related to cetuximab monotherapy in patients with colorectal cancer

Cetuximab is a monoclonal antibody that specifically blocks the epidermal growth factor receptor pathway. Cetuximab is now a standard drug to treat refractory advanced colorectal cancer. The most common side effect is a rash, seen in most patients. Ocular toxicity is uncommon. We report 2 cases of ocular toxicity characterized by blepharitis and conjunctivitis related to cetuximab administration. Strategies for management are discussed.

Phase I study of gefitinib plus FOLFIRI in previously untreated patients with metastatic colorectal cancer

BACKGROUND

In this study, the maximum tolerated dose and toxicity profile of FOLFIRI (infusional fluorouracil [5-FU]/leucovorin/irinotecan) plus gefitinib (an oral inhibitor of the epidermal growth factor receptor) were evaluated as first-line therapy in patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Sixteen patients participated in this study. Oral gefitinib was administered at 250 mg or 500 mg daily in 2 dose-escalation cohorts. FOLFIRI was administered without dose escalation on a 14-day cycle with treatment on day 1 with irinotecan 180 mg/m2, leucovorin 200 mg/m2, and 5-FU 400 mg/m2 bolus, followed by 5-FU 2400 mg/m2 continuous infusion over 46 hours.

RESULTS

The maximum tolerated dose of gefitinib was 250 mg, with diarrhea and neutropenia noted as the principal dose-limiting toxicities. Dose reductions in 5-FU and irinotecan were required in 4 patients because of diarrhea and 1 patient because of neutropenia. A partial response was observed in 25% of patients, and 56% had stable disease for > 12 weeks, corresponding to a disease control rate of 81%.

CONCLUSION

These findings suggest that gefitinib can be safely combined with FOLFIRI as first-line treatment of metastatic CRC and support the safety of further investigations of EGFR tyrosine kinase inhibitors with multiagent chemotherapy in this patient population.

An adaptive dose-finding design incorporating both toxicity and efficacy

Novel therapies are challenging the standards of drug development. Agents with specific biologic targets and limited toxicity require novel designs to determine doses to be taken forward into larger studies. In this paper, we describe an approach that incorporates both toxicity and efficacy data into the estimation of the biologically optimal dose of an agent in a phase I trial. The approach is based on the flexible continuation-ratio model, and uses straightforward optimal dose selection criteria. Dose selection is based on all patients treated up until that time point, using a continual reassessment method approach. Dose-outcome curves considered include monotonically increasing, monotonically decreasing, and unimodal curves. Our simulation studies demonstrate that the proposed design, which we call TriCRM, has favourable operating characteristics.

Epidermal growth factor receptor as a major anticancer drug target

Epidermal growth factor receptor (EGFR) is the best characterised member of the ErbB family of receptors. A lot of effort has been made to exploit the therapeutic potential of drugs acting on this receptor pathway. Monoclonal antibodies and oral tyrosine kinase inhibitors have undergone a thorough evaluation, both as single agents and in combination. However, over recent years, cancer cells have been shown to be able to harness different growth factor signalling pathways, so that single-agent therapy may not be the best way to use anti-EGFR drugs. Combinations with downstream effectors or other receptor-targeted therapies, or antiangiogenic compounds can be looked at more optimistically as effective weapons.