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

Advances in the treatment of metastatic colorectal cancer

The overall 5-year survival rate for patients with metastatic colorectal cancer (CRC) is less than 10%. Median survival with 5-fluorouracil (5-FU)/leucovorin (LV) therapy is approximately 12 months. Recent additions to the chemotherapy armamentarium for this disease have begun to prolong median survival times. In trials in which patients are exposed to all three approved chemotherapy agents, oxaliplatin, irinotecan, and 5-FU/LV, or capecitabine during the course of their disease, median survival has reached 20 months. The addition of oxaliplatin and irinotecan to 5-FU/LV regimens has also led to the maintenance of quality of life for longer intervals than were traditionally observed with 5-FU/LV alone. Current standard first-line regimens for metastatic CRC are FOLFOX (infusional 5-FU/LV with oxaliplatin) and FOLFIRI (infusional 5-FU/LV with irinotecan). The addition of bevacizumab to a two-drug regimen (irinotecan with 5-FU/LV) prolongs median survival to 20 months, with a modest amount of additional toxicity. Improvements in this median survival have not yet been realized with modifications to the current standard regimens; however, the oral agent capecitabine appears to be a reasonable substitute for infusional 5-FU/LV in combination regimens or as a single agent, with the advantage of reducing the inconvenience of the long infusion time. Ongoing investigations will identify a place for capecitabine, epidermal growth factor inhibitors, and new cytotoxics in the treatment of metastatic CRC.

Cetuximab and irinotecan interact synergistically to inhibit the growth of orthotopic anaplastic thyroid carcinoma xenografts in nude mice

PURPOSE

Anaplastic thyroid carcinoma (ATC) remains one of the most lethal known human cancers. Targeted molecular therapy with cetuximab, a monoclonal antibody against epidermal growth factor receptor, offers new treatment potentials for patient with ATC. Cetuximab has also been reported to have synergistic effects when combined with irinotecan, a topoisomerase inhibitor. Therefore, we hypothesized that cetuximab and irinotecan would be effective in inhibiting the growth and progression of ATC in a murine orthotopic model.

EXPERIMENTAL DESIGN

The in vitro antiproliferative effects of cetuximab and irinotecan on ATC cell line ARO were examined. We also studied the in vivo effects of cetuximab and irinotecan on the growth, invasion, and metastasis of orthotopic ATC tumors in nude mice. The in vivo antitumor efficacy of cetuximab/irinotecan combination was also compared with that of doxorubicin.

RESULTS

Cetuximab alone did not show any antiproliferative or proapoptotic effect on this cell line. However, when combined with irinotecan, cetuximab potentiated the in vitro antiproliferative and proapoptotic effect of irinotecan. Cetuximab, irinotecan, and cetuximab/irinotecan combination resulted in 77%, 79%, and 93% in vivo inhibition of tumor growth, respectively. Incidences of lymph node metastasis, laryngeal invasion, and tumor microvessel density were also significantly decreased in these treatment groups. Furthermore, the cetuximab/irinotecan combination was significantly more effective than doxorubicin in inhibiting the growth of orthotopic ATC xenografts.

CONCLUSIONS

Combination therapy with cetuximab/irinotecan inhibits the growth and progression of orthotopic ATC xenografts in nude mice. Given the lack of curative options for patients with ATC, combination therapy with cetuximab and irinotecan treatment warrants further study.

The combination of capecitabine and thalidomide in previously treated, refractory metastatic colorectal cancer

BACKGROUND

With the increasing survival of patients with metastatic colorectal cancer (CRC) there is a growing need for effective second- and third-line agents. We conducted a multicenter, phase II study to examine the combination of capecitabine and thalidomide (Cape/Thal) in patients with refractory metastatic CRC.

METHODS

Patients with previously treated stage IV CRC were eligible. Treatment consisted of capecitabine at 1,000 mg/m2 po BID for 14 days every 3 weeks and thalidomide, starting at 200 mg po QD continuously. Thalidomide was escalated individually to 600 mg po QD as tolerated. We analyzed overall survival (OS), progression-free survival, response, and toxicity rates.

RESULTS

Thirty-four eligible patients were enrolled. The median age was 57 years, and most patients had a normal performance status (65%). All patients had received prior chemotherapy and 19 (56%) had received 2 or 3 prior regimens. The median number of Cape/Thal cycles administered was 3 (range, 1-15). Grade 3/4 toxicities included fatigue (15%), venous thromboembolic events (12%), somnolence (12%), and constipation (9%). Grade 2 hand-foot syndrome occurred in 5 (15%) patients. There were no radiographic responses; 13 patients (38%) achieved stable disease. The median PFS was 2.6 months (95% confidence interval [CI] = 2.2-3.9) and the median OS was 7.1 month (95% CI = 5.2-12.0).

CONCLUSIONS

Though well-tolerated, the combination of capecitabine and thalidomide was not associated with objective tumor responses in a population of patients with previously treated metastatic CRC.

FOLFOX alternated with FOLFIRI as first-line chemotherapy for metastatic colorectal cancer

BACKGROUND

5-fluorouracil (5-FU), irinotecan, and oxaliplatin are the most active drugs in advanced colorectal cancer (CRC), and survival is improved with patient exposure to all of them. The efficacy and safety of an alternating schedule of continuous-infusion 5-FU with leucovorin (LV) plus oxaliplatin (ie, FOLFOX regimen) or irinotecan (ie, FOLFIRI regimen) was assessed in the first-line setting.

PATIENTS AND METHODS

Seventy-nine patients with previously untreated, unresectable CRC were included. Treatment consisted of 5-FU/LV (de Gramont schedule) plus oxaliplatin (85 mg/m2) alternated biweekly with the same 5-FU/LV regimen plus irinotecan (180 mg/m2). Treatment was maintained until tumor progression or unacceptable toxicity was noted.

RESULTS

Median age was 62 years. Performance status was 0/1 in 91% of patients, 63% had 1 organ involved, and 80% had liver metastases. A median of 6 courses per patient (range, 1-9) and a total of 952 infusions were given. The most frequent grade 3/4 toxic events were neutropenia (32%), diarrhea (26%), and asthenia (7%). Grade 1/2 neurotoxicity was seen in 59% of cases, but no grade 3/4 neurotoxicity was observed. There were no toxic deaths. An objective response rate of 54% (4 complete responses plus 39 partial responses) was attained. Median time to progression and overall survival were 13 months and 18 months, respectively.

CONCLUSION

This alternating schedule is active, with efficacy results similar to those seen with sequential protocols, the advantages of less toxicity, and 100% patient exposure to irinotecan and oxaliplatin.

Lymphocyte therapy of renal cell carcinoma

During the past 20 years, there has been considerable interest in lymphocyte therapy as a treatment for renal cell carcinoma. There is no therapeutic role for B-lymphocyte therapy, but their products, monoclonal antibodies, now have widespread clinical applications. The major types of autologous lymphocyte therapy that have been explored in clinical trials are cytotoxic lymphokine-activated killer cells, which are natural killer cells and T-cells that have been stimulated in vitro by interleukin-2 or other similar cytokines; cytotoxic and noncytotoxic tumor infiltrating lymphocytes, which are T-cells derived from tumor tissue; other tumor antigen-stimulated T-lymphocytes derived from regional lymph nodes or peripheral blood; and noncytotoxic lymphocytes of the memory/helper phenotype. More recently, allogeneic immune therapy using nonmyeloablative hematopoietic stem cell transplant and/or donor lymphocyte therapy has also shown promise.

Phase III randomized trial of cisplatin plus placebo compared with cisplatin plus cetuximab in metastatic/recurrent head and neck cancer: an Eastern Cooperative Oncology Group study

PURPOSE

Therapy of recurrent/metastatic squamous cell carcinoma of the head and neck results in median progression-free survival (PFS) of 2 months. These cancers are rich in epidermal growth factor receptor (EGFR). We wished to determine whether the addition of cetuximab, which inhibits activation of EGFR, would improve PFS.

PATIENTS AND METHODS

Patients with recurrent/metastatic squamous cell carcinoma of the head and neck were randomly assigned to receive cisplatin every 4 weeks, with weekly cetuximab (arm A) or placebo (arm B). Tumor tissue was assayed for EGFR expression by immunohistochemistry. The primary end point was PFS. Secondary end points of interest were response rate, toxicity, overall survival, and correlation of EGFR with clinical end points.

RESULTS

There were 117 analyzable patients enrolled. Median PFS was 2.7 months for arm B and 4.2 months for arm A. The hazard ratio for progression of arm A to arm B was 0.78 (95% CI, 0.54 to 1.12). Median overall survival was 8.0 months for arm B and 9.2 months for arm A (P = .21). The hazard ratio for survival by skin toxicity in cetuximab-treated patients was 0.42 (95% CI, 0.21 to 0.86). Objective response rate was 26% [corrected] for arm A and 10% [corrected] for arm B (P = .03). Enhancement of response was greater for patients with EGFR staining present in less than 80% of cells.

CONCLUSION

Addition of cetuximab to cisplatin significantly improves response rate. There was a survival advantage for the development of rash. Progression-free and overall survival were not significantly improved by the addition of cetuximab in this study.

The progress and promise of molecular imaging probes in oncologic drug development

As addressed by the recent Food and Drug Administration Critical Path Initiative, tools are urgently needed to increase the speed, efficiency, and cost-effectiveness of drug development for cancer and other diseases. Molecular imaging probes developed based on recent scientific advances have great potential as oncologic drug development tools. Basic science studies using molecular imaging probes can help to identify and characterize disease-specific targets for oncologic drug therapy. Imaging end points, based on these disease-specific biomarkers, hold great promise to better define, stratify, and enrich study groups and to provide direct biological measures of response. Imaging-based biomarkers also have promise for speeding drug evaluation by supplementing or replacing preclinical and clinical pharmacokinetic and pharmacodynamic evaluations, including target interaction and modulation. Such analyses may be particularly valuable in early comparative studies among candidates designed to interact with the same molecular target. Finally, as response biomarkers, imaging end points that characterize tumor vitality, growth, or apoptosis can also serve as early surrogates of therapy success. This article outlines the scientific basis of oncology imaging probes and presents examples of probes that could facilitate progress. The current regulatory opportunities for new and existing probe development and testing are also reviewed, with a focus on recent Food and Drug Administration guidance to facilitate early clinical development of promising probes.

Neoadjuvant chemotherapy prior to preoperative chemoradiation or radiation in rectal cancer: should we be more cautious?

Neoadjuvant chemotherapy (NACT) is a term originally used to describe the administration of chemotherapy preoperatively before surgery. The original rationale for administering NACT or so-called induction chemotherapy to shrink or downstage a locally advanced tumour, and thereby facilitate more effective local treatment with surgery or radiotherapy, has been extended with the introduction of more effective combinations of chemotherapy to include reducing the risks of metastatic disease. It seems logical that survival could be lengthened, or organ preservation rates increased in resectable tumours by NACT. In rectal cancer NACT is being increasingly used in locally advanced and nonmetastatic unresectable tumours. Randomised studies in advanced colorectal cancer show high response rates to combination cytotoxic therapy. This evidence of efficacy coupled with the introduction of novel molecular targeted therapies (such as Bevacizumab and Cetuximab), and long waiting times for radiotherapy have rekindled an interest in delivering NACT in locally advanced rectal cancer. In contrast, this enthusiasm is currently waning in other sites such as head and neck and nasopharynx cancer where traditionally NACT has been used. So, is NACT in rectal cancer a real advance or just history repeating itself? In this review, we aimed to explore the advantages and disadvantages of the separate approaches of neoadjuvant, concurrent and consolidation chemotherapy in locally advanced rectal cancer, drawing on theoretical principles, preclinical studies and clinical experience both in rectal cancer and other disease sites. Neoadjuvant chemotherapy may improve outcome in terms of disease-free or overall survival in selected groups in some disease sites, but this strategy has not been shown to be associated with better outcomes than postoperative adjuvant chemotherapy. In particular, there is insufficient data in rectal cancer. The evidence for benefit is strongest when NACT is administered before surgical resection. In contrast, the data in favour of NACT before radiation or chemoradiation (CRT) is inconclusive, despite the suggestion that response to induction chemotherapy can predict response to subsequent radiotherapy. The observation that spectacular responses to chemotherapy before radical radiotherapy did not result in improved survival, was noted 25 years ago. However, multiple trials in head and neck cancer, nasopharyngeal cancer, non-small-cell lung cancer, small-cell lung cancer and cervical cancer do not support the routine use of NACT either as an alternative, or as additional benefit to CRT. The addition of NACT does not appear to enhance local control over concurrent CRT or radiotherapy alone. Neoadjuvant chemotherapy before CRT or radiation should be used with caution, and only in the context of clinical trials. The evidence base suggests that concurrent CRT with early positioning of radiotherapy appears the best option for patients with locally advanced rectal cancer and in all disease sites where radiation is the primary local therapy.

Increased toxicity with gefitinib, capecitabine, and radiation therapy in pancreatic and rectal cancer: phase I trial results

PURPOSE

Overexpression of epidermal growth factor receptor (EGFR) has been associated with aggressive tumor phenotypes, chemotherapy, and radiation resistance, as well as poor survival in preclinical and clinical models. The EGFR inhibitor gefitinib potentiates chemotherapy and radiation tumor cytotoxicity in preclinical models, including pancreatic and colorectal cancer. We initiated two phase I trials assessing the combination of gefitinib, capecitabine, and radiation in patients with localized pancreatic and rectal cancer.

PATIENTS AND METHODS

Patients with pathologically confirmed adenocarcinoma of the pancreas and rectum were eligible. Pretreatment staging included computed tomography, endoscopic ultrasound, and surgical evaluation. Patients received 50.4 Gy of external-beam radiation therapy to the tumor in 28 fractions. Capecitabine and gefitinib were administered throughout the radiation course. Following completion, patients were restaged and considered for resection. Primary end points included determination of dose-limiting toxicity (DLT) and a phase II dose; secondary end points included determination of non-DLTs and preliminary radiographic and pathologic response rates.

RESULTS

Ten patients were entered in the pancreatic study and six in the rectal study. DLT was seen in six of 10 patients in the pancreatic study and two of six patients in the rectal study. The primary DLT in both studies was diarrhea. Two patients developed arterial thrombi.

CONCLUSION

The combination of gefitinib, capecitabine, and radiation in pancreatic and rectal cancer patients resulted in significant toxicity. A recommended phase II dose was not determined in either of our studies. Further investigation with this combination should be approached with caution.

Profile of plasma angiogenic factors before and after hepatectomy for colorectal cancer liver metastases

BACKGROUND

Circulating angiogenic factors in patients with colorectal cancer liver metastases may promote tumor growth and contribute to liver regeneration after partial hepatectomy.

METHODS

We analyzed blood samples from 26 patients with colorectal cancer liver metastases before and after liver resection and used samples from 20 healthy controls as a reference. Plasma levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and hepatocyte growth factor (HGF) were measured, and levels were correlated with recurrence.

RESULTS

The median preoperative levels of all four factors were significantly higher and more variable in colorectal cancer liver metastasis patients than in controls. HGF and bFGF levels increased significantly 3 days and 1 month after hepatectomy, respectively, and returned to near preoperative levels at 3 months. Postoperative VEGF and EGF levels remained relatively stably increased over 3 months. After a median follow-up of 19 months, 10 patients (42%) experienced recurrence. Higher preoperative VEGF and HGF levels correlated with subsequent recurrence (P = .018 and .021, respectively), and a preoperative adjusted total value of all four factors accurately identified patients at low, moderate, and high risk of recurrence (P = .034). Patients who experienced disease recurrence also had relatively higher bFGF levels 3 months after operation (P = .035).

CONCLUSIONS

Plasma angiogenic factors are increased in patients with colorectal cancer liver metastases and remain increased at least 3 months after partial hepatectomy. Measurement of certain factors before and after hepatic resection can predict recurrence. Targeted biological agents may counteract the tumor-promoting effects of these circulating factors on subclinical disease.

Drug Insight: Metastatic colorectal cancer--oral fluoropyrimidines and new perspectives in the adjuvant setting

Capecitabine and uracil/ftorafur (UFT) are prodrugs of 5-fluorouracil (5-FU) that can be administered orally. Both drugs have been shown to be as effective as bolus 5-FU and folinic acid (FA), both as adjuvant treatment, and for the treatment of metastatic colorectal cancer. However, as the addition of oxaliplatin to 5-FU has been shown to improve disease-free survival in adjuvant therapy, oxaliplatin/5-FU is currently regarded as the standard adjuvant treatment, rather than fluoropyrimidine monotherapy. For the treatment of metastatic colorectal cancer, improved response rates and prolonged survival have been reported when irinotecan or oxaliplatin was added to 5-FU/FA; a further increase in efficacy was shown when bevacizumab, an antibody to vascular endothelial growth factor, was added to chemotherapy. Studies investigating the substitution of infusional 5-FU with oral compounds in combination therapy (e.g. FOLFOX versus capecitabine/oxaliplatin) are ongoing, but preliminary results in metastatic patients advise caution because of increased toxicity when used with irinotecan, and statistically non-significant trends of a decreased efficacy when used with oxaliplatin. Therefore, the combined use of oral 5-FU prodrugs plus irinotecan or oxaliplatin is not recommended at present. Oral 5-FU prodrugs, however, offer a convenient and less toxic treatment option in adjuvant treatment and in the treatment of advanced colorectal carcinoma in patients who do not want an intensified regimen, those that have contraindications for implanted venous access devices, and those who are not candidates for a combination therapy with irinotecan and oxaliplatin.

Anti-CD3 x anti-epidermal growth factor receptor (EGFR) bispecific antibody redirects T-cell cytolytic activity to EGFR-positive cancers in vitro and in an animal model

PURPOSE

Targeting epidermal growth factor receptor (EGFR) overexpressed by many epithelial-derived cancer cells with anti-EGFR monoclonal antibodies (mAb) inhibits their growth. A limited number of clinical responses in patients treated with the anti-EGFR mAb, (cetuximab), may reflect variability in EGFR type or signaling in neoplastic cells. This study combines EGFR-targeting with the non-MHC-restricted cytotoxicity of anti-CD3 activated T cells (ATC) to enhance receptor-directed cytotoxicity.

EXPERIMENTAL DESIGN

ATC from normal and patient donors were expanded ex vivo. Specific cytolytic activity of ATC armed with anti-CD3 x anti-EGFR (EGFRBi) against EGFR-expressing cancer cells derived from lung, pancreas, colon, prostate, brain, skin, or EGFR-negative breast cancer cells was evaluated in (51)Cr release assays. In vivo studies comparing tumor growth delay induced by EGFRBi-armed ATCs or cetuximab were done in severe combined immunodeficient/Beige mice (SCID-Beige) bearing COLO 356/FG pancreatic and LS174T colorectal tumors.

RESULTS

At effector/target ratios from 3.125 to 50, both EGFRBi-armed normal and patient ATC were significantly more cytotoxic, by 23% to 79%, against EGFR-positive cells over ATC, cetuximab, anti-CD3 alone, or ATC armed with irrelevant BiAb directed at CD20. EGFRBi-armed ATC also secreted significantly higher levels of some T(H1)/T(H2) cytokines compared with ATC alone. In mice, i.v. infusions of EGFRBi-armed ATC (0.001 mg equivalent/infusion) were equally effective as cetuximab (1 mg/infusion) alone for significantly delaying growth of established COLO 356/FG but not LS174T tumors compared with mice that received ATC alone or vehicle (P < 0.001).

CONCLUSIONS

Combining EGFR antibody targeting with T cell-mediated cytotoxicity may overcome some limitations associated with EGFR-targeting when using cetuximab alone.

Rapid evolution in colorectal cancer: therapy now and over the next five years

A large number of patients with colorectal cancer have relatively early disease, and thus, adjuvant therapy has the potential to save lives. In stage III patients, there has been a steady improvement in 3-year disease-free survival with the use of 5-fluorouracil/leucovorin (5-FU/LV) regimens and capecitabine (Xeloda); Hoffmann-La Roche Inc., Nutley, NJ, http://www.rocheusa.com) regimens. A median survival longer than 20 months was observed in patients with metastatic disease when treated with combination chemotherapy containing oxaliplatin (Eloxatin); Sanofi-Synthelabo Inc., New York, http://www.sanofi-synthelabo.us) or irinotecan (Camptosar); Pfizer Pharmaceuticals, New York, http://www.pfizer.com). This has led to 5-FU/LV/oxaliplatin becoming standard therapy, along with 5-FU/LV/irinotecan. New data confirm the beneficial effect on disease-free survival of adding oxaliplatin to adjuvant colorectal cancer regimens based on 5-FU. These regimens show an effect when given in bolus as well as in infusional schedules. Interest in future adjuvant regimens focuses on the potential additional benefit of molecularly targeted agents, such as bevacizumab (Avastin); Genentech, Inc., South San Francisco, CA, http://www.gene.com), and on the ability of applied genomics to distinguish between high- and low-risk populations.

Changing patterns of bone and brain metastases in patients with colorectal cancer

BACKGROUND

Therapeutic advances for patients with metastatic colorectal cancer (CRC) have been associated with prolonged survival. This study was undertaken to test the hypothesis that expanded treatment options and resultant improved survival for patients with metastatic CRC are associated with an increased incidence of metastases at uncommon sites.

PATIENTS AND METHODS

Patients with metastatic CRC evaluated from 1993 to 2002 at the Fox Chase Cancer Center were identified. Medical records were abstracted to obtain the following: date of diagnosis/metastasis, primary tumor site, therapeutic agents received, survival, and site(s) of metastases.

RESULTS

The records of 1020 patients were reviewed. Incidence of bone and brain metastases were 10.4% (95% CI, 8.6%-12.4%) and 3% (95% CI, 2.2%-4.5%), respectively. Bone metastases were more common with increased numbers of active systemic agents received: 0 (3.7%), 1 (9.4%), 2 (10.9%), 3 (16.3%), and 4/5 (17.4%; P = 0.001; trend test). Patients receiving irinotecan or oxaliplatin were more likely to develop bone metastases (13.2% vs. 8.3%, P = 0.01 for irinotecan; 16.9% vs. 9%, P = 0.003 for oxaliplatin). Patients with primary rectal versus primary colon cancer were more likely to develop bone metastases (16% vs. 8.6%; P = 0.001). Patients with lung metastases were more likely to have bone metastases (16.1% vs. 6.4%; P < 0.0001) or brain metastases (6.2% vs. 1.2%; P < 0.0001) than those without.

CONCLUSION

These data demonstrate that the incidence of bone and brain metastases in patients with CRC is more common than previously reported and is associated with receipt of multiple systemic treatments. As survival improves for this patient population, clinicians should be aware of the potential for metastases at previously uncommon sites.

Metastatic colorectal cancer: first- and second-line treatment in 2005

First-, second-, and third-line therapies for the treatment of metastatic colorectal cancer may influence choices for subsequent therapy. First-line treatment for metastatic colorectal cancer depends largely on combination chemotherapy regimens that have been proven to prolong survival, control disease progression, and improve quality of life, without excessive toxicity. Standard therapies include 5-fluorouracil, irinotecan, and oxaliplatin, but other combination therapies are currently under investigation. An upcoming area of study includes agents that target vascular endothelial growth factor and epidermal growth factor receptor. While doublet therapy is more active than 5-fluorouracil alone, triplet therapy is also emerging. Second-line therapy is dependent upon prior treatment, and second-line FOLFIRI or FOLFOX regimens that incorporate 5-fluorouracil, leucovorin, and either irinotecan or oxaliplatin, respectively, are still in question because of residual toxicities. After combination chemotherapy, a non-cross-resistant chemotherapy is the best choice. Second-line targeted therapy has been well-tolerated and active in several trials. Future developments will most likely occur in the areas of pharmacogenetics (eg, toxicity, age, comorbidities, patient choice, strategy of cure, palliation) and pharmacogenomics (eg, resistance/activity, gene expression) to produce individualized therapies for patients. The type of adjuvant treatment, genomic consideration, and genetic predisposition will be determining factors in the ideal protocol for first-line therapy.

Randomized phase II trial of the clinical and biological effects of two dose levels of gefitinib in patients with recurrent colorectal adenocarcinoma

PURPOSE

The clinical objective of this trial was to evaluate gefitinib in patients with metastatic colorectal cancer that had progressed despite prior treatment. Serial tumor biopsies were performed when possible and analyzed for activation of the epidermal growth factor receptor (EGFR) signaling pathway. Serial serum samples were measured for amphiregulin and transforming growth factor-alpha (TGFalpha).

PATIENTS AND METHODS

One hundred fifteen patients were randomly assigned to receive gefitinib 250 or 500 mg orally once a day. One hundred ten patients were assessable for clinical efficacy. Biologic evaluation was performed on paired tumor samples from 28 patients and correlated with clinical outcome.

RESULTS

Median progression-free survival was 1.9 months (95% CI, 1.8 to 2.1 months) and 4-month progression-free survival rate was 13% +/- 5%. One patient achieved a radiographic partial response (RR = 1%; 95% CI, 0.01% to 5%). Median survival was 6.3 months (95% CI, 5.1 to 8.2 months). The most common adverse events were skin rash, diarrhea, and fatigue. In the biopsy cohort, expression of total or activated EGFR, activated Akt, activated MAP-kinase, or Ki67 did not decrease following 1 week of gefitinib. However, a trend toward decreased post-treatment levels of activated Akt and Ki67 was observed in patients with a PFS higher than the median, although these did not reach the .05 level of significance.

CONCLUSION

Gefitinib is inactive as a single agent in patients with previously treated colorectal cancer. In tumor samples, gefitinib did not inhibit activation of its proximal target, EGFR. Trends were observed for inhibition of downstream regulators of cellular survival and proliferation in patients achieving longer progression-free survival.

Molecular mechanisms and targeting of colorectal cancer

Targeted therapies that are approved for metastatic colorectal cancer are divided into two groups: those affecting vascular endothelial growth factor (VEGF) known to interrupt tumor growth and metastasis (also called neo-angiogenesis), and agents that affect the tumor directly by interrupting the epidermal growth factor (EGF) and its receptor. Anti-angiogenic VEGF therapies are divided into two categories: one affecting the VEGF ligand, such as bevacizumab, and those that inhibit the VEGF receptor, such as PTK/ZK. Epidermal growth factor receptor (EGFR) therapies are divided into monoclonal antibodies that affect EGFR, such as cetuximab, and EGFR tyrosine kinase inhibitors, such as gefitinib. Both VEGF and EGFR areas of treatment have shown promising efficacy in first-line, combination therapy settings. Future targeted therapeutic strategies include gene profiling, combinations of capecitabine and oxaliplatin, with bevacizumab and/or cetuximab therapies.

EGFR as a Target: Rationale for Therapy

OBJECTIVES

To review the biology of the EGFR, its structure, and the associated signal transduction pathways. To provide an overview of the role of EGFR in normal physiology and the pathophysiology of malignancy. Current anti-EGFR treatments are also discussed.

DATA SOURCES

Research articles.

CONCLUSION

EGFR is a valid target in the treatment of solid tumors. EGFR abnormalities and dysfunction are involved in various aspects of carcinogenesis and tumor progression, and EGFR is overexpressed in several tumor types. The development of anti-EGFR therapies represents an important advance in cancer therapy.

IMPLICATIONS FOR NURSING PRACTICE

Anti-EGFR therapy is currently available in the clinical setting. Nurses involved in the care of patients with cancer can benefit from an increased understanding of the normal and abnormal function of EGFR in the body and the mechanisms by which anti-EGFR therapies act.

Hautveränderungen nach Blockade des Epidermal-growth-factor-Rezeptors

Malignant tumors are increasingly being treated with therapeutic agents having molecular mechanisms of action (so-called biologics). These include therapeutic agents for the blockade of epidermal growth factor receptor (EGFR). The adverse drug reaction profile associated with EGFR inhibitors is dominated by cutaneous lesions. Most common are acneiform skin reactions followed by xerosis, eczema and changes to the hair and nails. The cutaneous changes vary greatly between individuals and may be relatively insignificant. However, they may also prevent continuation of therapy. During the use of EGFR inhibitors, a correlation was observed between the severity of cutaneous changes and the effectiveness of the therapeutic agent, a finding potentially useful for individual dose adjustment.

Antiangiogenic chimeric anti-endoglin (CD105) antibody: pharmacokinetics and immunogenicity in nonhuman primates and effects of doxorubicin

We generated a human/mouse chimeric antibody c-SN6j of human IgG1 isotype from a murine anti-human endoglin (EDG) monoclonal antibody (mAb) SN6j that suppressed angiogenesis, tumor growth and metastasis in mice. We determined pharmacokinetics (PKs) and immunogenicity of c-SN6j in monkeys after multiple i.v. injections. A dose-escalation study was performed by administration of c-SN6j into six monkeys at the dose of 1 mg, 3 mg and 10 mg per kg body weight. In addition, both c-SN6j (3 mg/kg) and doxorubicin (0.275 mg/kg) were injected into two monkeys. c-SN6j and doxorubicin were injected twice a week for 3 weeks. We developed a unique and sensitive ELISA by sequentially targeting the common and idiotypic epitopes of c-SN6j-Fv to quantify plasma c-SN6j. Application of the ELISA showed that increasing the c-SN6j dose resulted in a proportional increase in the circulating c-SN6j after the first injection. In addition, the estimated area under the curve (AUC) for the first injection of c-SN6j is proportional to dose. We carried out detailed analyses of PKs of c-SN6j during and after the repeated injections. Our model of PKs fitted the empirical data well. Addition of doxorubicin modulated the PK parameters. We developed two ELISAs to separately determine the immune responses to the murine part and the human part of c-SN6j in monkeys. Interestingly, the murine part induced a weaker immune response than the human part. Doxorubicin potentiated the immune responses. Increasing the dose of c-SN6j increased plasma levels of c-SN6j but did not increase the immune responses to c-SN6j.

Interaction of the epidermal growth factor receptor and the DNA-dependent protein kinase pathway following gefitinib treatment

The epidermal growth factor receptor (EGFR) is an important target for cancer therapy. We previously showed that the EGFR inhibitor gefitinib modulated repair of DNA damage following exposure to cisplatin and etoposide involving the DNA-dependent protein kinase (DNA-PK) pathway. In this study, we specifically investigated the effect of EGFR inhibition by gefitinib on functional activity of DNA-PK in cancer cell lines and the interaction between EGFR and DNA-PK. The effects of DNA-PK inhibition by wortmannin and small interfering RNA to the catalytic subunit of DNA-PK (DNA-PK(CS)) on cell proliferation and DNA interstrand cross-link repair were investigated in the human MCF-7 breast cancer cell line and compared with the effects of gefitinib. DNA-PK activity was quantitated and expression measured by immunoblotting following gefitinib treatment. Immunoprecipitation experiments were done with and without gefitinib in MCF-7 cells, the AR42J pancreas cell line with high EGFR, and the human MDA-453 breast cancer cell line expressing low EGFR. Nuclear and cytoplasmic extracts were immunoblotted with antibody to DNA-PK(CS) to determine if gefitinib treatment altered cellular expression. Reduction of DNA-PK activity by wortmannin and expression by small interfering RNA to DNA-PK(CS) sensitized cells to cisplatin and inhibited repair of cisplatin-induced interstrand cross-links. Gefitinib treatment reduced DNA-PK activity in MCF-7 and AR42J but not MDA-453 cells. Immunoprecipitation experiments showed interaction between EGFR and DNA-PK(CS) in a dose-dependent and time-dependent manner following gefitinib treatment in MCF-7 and AR42J but not MDA-453 cells. Gefitinib treatment reduced nuclear expression and increased cytosolic expression of DNA-PK(CS) in MCF-7 and AR42J but not MDA-453 cells. Treatment with gefitinib modulates association of EGFR and DNA-PK(CS). This is correlated with decreased function of DNA-PK(CS). Inhibition of DNA-PK(CS) may be an important factor in sensitization to chemotherapy and radiation following treatment with inhibitors of the EGFR pathway.

Irreversible pan-ErbB tyrosine kinase inhibitor CI-1033 induces caspase-independent apoptosis in colorectal cancer DiFi cell line

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of colorectal carcinomas and represents a target for therapeutic interventions with signal transduction inhibitors. We investigated the ability of CI-1033 to induce apoptosis and inhibition of proliferation in the colorectal cancer cell lines DiFi and Caco-2, which both express high levels of EGFR. While in Caco-2 cells CI-1033 treatment at a concentration 0.1 microM for 72 hours demonstrated only antiproliferative (53.7 +/- 4.3%) but no pro-apoptotic effects, treatment of DiFi cells resulted in a reduced proliferation rate (31.4 +/- 3.1%) and in apoptosis (44.2 +/- 8.9%). In order to define proteins involved in the regulation of apoptosis, we aimed to determine differences in the proteome profile of both cell lines before and after treatment with CI-1033. Cellular proteins were analyzed by 2-D gel electrophoresis followed by computational image analysis and mass spectrometry. Our data show that DiFi cells differ from Caco-2 cells in nine significantly upregulated proteins, and their potential role in apoptosis is described. We demonstrate that induction of apoptosis was triggered via caspase-independent pathways. Overexpression of leukocyte elastase inhibitor (LEI) and translocation of cathepsin D to the cytosol accompanied by upregulation of other defined proteins resulted in Bax-independent AIF translocation from mitochondria into the nucleus and apoptosis. Definition of these proteins can pave the way for functional studies and contribute to a better understanding of the effects of CI-1033 and the pathways of caspase-independent cell death.

Chemotherapy-induced carcinoembryonic antigen surge in patients with metastatic colorectal cancer

OBJECTIVES

To investigate the incidence of carcinoembryonic antigen (CEA) surge in patients with metastatic colorectal cancer (MCRC) and its implications on clinical outcome.

METHODS

A retrospective chart review of patients with MCRC treated with chemotherapy at Roswell Park Cancer Institute from January 2000 to May 2004 was conducted. A CEA surge was defined as an increase of >20% from baseline followed by a >20% drop in one or more subsequent CEA levels compared to baseline. The incidence of CEA surge and its association with clinical outcome was investigated.

RESULTS

Eighty-nine patients were evaluable for CEA surge. A CEA surge was documented in 10 patients. The CEA surge lasted <4 months in all 10 patients and was associated with a clinical benefit. No significant correlation was noted between CEA surge and site of primary tumor, site of metastatic disease, or tumor differentiation.

CONCLUSIONS

CEA surges can be observed in patients receiving chemotherapy for MCRC and are often associated with a clinical benefit. None of the CEA surges satisfied the American Society of Clinical Oncology definition of CEA progression. A rise in CEA after initiation of chemotherapy, unless lasting >4 months, cannot be used as an indicator of progressive disease.

Anti-angiogenic treatment of gastrointestinal malignancies

The scientific rationale to block angiogenesis as a treatment strategy for human cancer has been developed over the last 30 years, but is only now entering the clinical arena. Preclinical studies have demonstrated the importance of the vascular endothelial growth factor (VEGF) pathways in both physiologic and pathologic angiogenesis, and have led to the development of approaches to block its role in tumor angiogenesis. Bevacizumab is an antibody to VEGF and has been shown to prolong survival when given with chemotherapy in the treatment of metastatic colorectal cancer (CRC). Although this is the first anti-angiogenic treatment to be approved for the treatment of human epithelial malignancy, a number of other approaches currently are in development. Soluble chimeric receptors to sequester serum VEGF and monoclonal antibodies against VEGF receptors have both shown considerable promise in the laboratory and are being brought into clinical investigation. A number of small-molecule tyrosine kinase inhibitors that have activity against VEGF receptors also are in clinical trials. Although these novel treatments are being pioneered in CRC, anti-angiogenic approaches also are being tested in the treatment of other gastrointestinal malignancies. Anti-VEGF therapy has shown promise in such traditionally resistant tumors as pancreatic cancer and hepatocellular carcinoma. This review will examine the preclinical foundation and then focus on the clinical studies of anti-VEGF therapy in gastrointestinal cancers.

Mechanisms of apoptosis-induction by rottlerin: therapeutic implications for B-CLL

Constitutively activated signaling pathways contribute to the apoptosis-defect of B-CLL cells. Protein kinase C-delta is a permanently activated kinase and a putative downstream target of phosphatidylinositol-3 kinase in B-CLL. Blockade of protein kinase C-delta (PKC-delta) by the highly specific inhibitor rottlerin induces apoptosis in chronic lymphocytic leukaemia (CLL) cells. By co-culturing bone marrow stromal and CLL cells, we determined that the proapoptotic effect of rottlerin is not abolished in the presence of survival factors, indicating that a targeted therapy against PKC-delta might be a powerful approach for the treatment of CLL patients. The downstream events following rottlerin treatment engage mitochondrial and non-mitochondrial pathways and ultimately activate caspases that execute the apoptotic cell death. Herein we report that the inhibition of PKC-delta decreases the expression of the important antiapoptotic proteins Mcl-1 and XIAP accompanied by a loss of the mitochondrial membrane potential Deltapsi. In addition, we discovered that ZAP-70-expressing cells are significantly more susceptible to rottlerin-induced cell death than ZAP-70 negative cells. We finally observed that rottlerin can augment cell toxicity induced by standard chemotherapeutic drugs. Conclusively, PKC-delta is a promising new target in the combat against CLL.

Cetuximab preclinical antitumor activity (monotherapy and combination based) is not predicted by relative total or activated epidermal growth factor receptor tumor expression levels

Although Erbitux (cetuximab) has proven therapeutic benefit in the clinical setting, the molecular determinants predicting responsiveness to this agent are still not very well understood. Here, we assessed the relationship between basal total and activated (pY1068) epidermal growth factor receptor (EGFR) levels in a tumor and the responsiveness to cetuximab monotherapy or combination-based treatment using human xenograft models. Cetuximab treatment alone (0.25-1 mg/mouse/injection, q3d, i.p.) effectively delayed the growth of GEO and L2987 tumors by a minimum of 10 days corresponding to log cell kill values of >or=1.0. Borderline activity was seen in the A549 and WiDr xenografts. However, cetuximab failed to show any significant antitumor activity in the HT29, HCT116, LOVO, Colo205, LX-1, HCC70, and N87 models. All of the studied tumors had detectable yet variable levels of EGFR. For combination regimens, cetuximab (1 mg/mouse/injection, q3dx5, i.p.) and cisplatin (4.5 mg/kg/injection, q3dx5, i.v.) proved to be significantly more efficacious than individual monotherapies in the cisplatin-refractory yet cetuximab-responsive GEO tumor model (P < 0.001). However, no therapeutic enhancement was observed in the cisplatin and cetuximab weakly responsive A549 xenograft. Similarly, combinations of CPT-11 (48 mg/kg/injection, q3dx5, i.v.) with cetuximab (1 mg/mouse/injection, q3dx5, i.p.) failed to show any improvements over individual monotherapies in the cetuximab resistant/weakly responsive HT29, A549, and WiDr models. We conclude that preclinical activity associated with cetuximab monotherapy does not correlate directly with relative basal levels of total or activated (pY1068) EGFR in a tumor. Moreover, robust single-agent activity by cetuximab may be the best predictor for this agent to potentiate chemotherapy-mediated antitumor activities.

Epidermal growth factor receptor-negative colorectal cancer: is there truly such an entity?

The epidermal growth factor receptor (EGFR) has been identified as a targer for anticancer therapies. Cetuximab is a chimeric murin-human monoclonal antibody that targets the extracellular domain of the EGFR. Based on the (un proven) assumption that the presence of this receptor would quantitatively correlate with activity of cetuximab, early clinical trials with cetuximab required demonstration of the receptor by immunohistochemical (IHC) techniques. However, assumptions were made regarding the stability of EGFR expression and the reproducibility of this IHC expression that , in retrospect, were almost certainly unrealistic and are incorrect. Current techniques lack the sensitivity and predictability to inform decisions as to the usefulness of cetuximab or other anti-EGFR therapies in the treatment of colorectal or other cancers. As such, the IHC staining for EGFR that is currently in use lacks any meaningful clinical predictive value and has no use in the management of patients with cancer. Current data do not support the use of the EGFR IHC stain for making any clinical decisions regarding patient management. No patient should be refused treatment with an EGFR-targeting agent solely on the basis of a negative EGFR IHC test and no patient should be given anti-EGFR therapy simply on the basis of a positive or strongly positive EGFR test result.

Recent data with anti-epidermal growth factor receptor antibodies and irinotecan in colon cancer

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of colorectal cancers. It is the target for a class of agents at the forefront of development for the treatment of colorectal cancer, ie, the anti-EGFR monoclonal antibodies, which include cetuximab, panitumumab, and matuzumab. At present, cetuximab is the furthest along in terms of established efficacy in the treatment of metastatic or inoperable disease and is licensed for the treatment of patients with irinotecan-refractory colorectal cancer. This article reviews the recent evidence supporting the combination of these anti-EGFR agents with the cytotoxic chemotherapeutic agent irinotecan.

Overview of monoclonal antibodies and small molecules targeting the epidermal growth factor receptor pathway in colorectal cancer

The epidermal growth factor receptor (EGFR) provides survival signals and is overexpressed in the majority of colorectal cancers. As more is learned about the molecular details of EGFR signaling, antibodies can be designed to interfere with specific domains of the EGFR molecule. In this review, we analyze preclinical and current clinical data on EGFR-targeting molecules and their potential role in the treatment of colorectal cancer. Cetuximab binds to domain III of EGFR and hinders ligand binding. It is now approved by the US Food and Drug Administration for metastatic colorectal cancer treatment. Panitumumab is another widely studied anti-EGFR antibody with similar properties. Bispecific antibodies are modified immunoglobulin molecules containing 2 different binding specificities. These antibodies can redirect the immune response against tumor cells by tethering effector cells such as CD3e-expressing T cells or CD16-expressing natural killer cells and granulocytes to the surface of cancer cells. Tyrosine kinase inhibitors are quinazoline-derived, low molecular weight synthetic molecules that can block the intracellular tyrosine kinase domain of several receptors, including EGFR, Erb2, and vascular endothelial growth factor receptor, and thereby inhibit ligand-induced receptor phosphorylation and abrogate the biologic effect of EGFR signaling. The presence of skin rash and EGFR gene amplification have been advanced as possible predictors of clinical effectiveness of targeted anti-EGFR therapies.

Adding pharmacogenomics to the development of new marine-derived anticancer agents

Nature has always been a highly productive tool in the development of anticancer therapies. Renewed interest in the potential of this tool has recently been sparked by the realization that the marine ecosystem can be used for the discovery and development of new compounds with clinical potential in advanced resistant tumors. These compounds can be incorporated into combination approaches in a chronic therapy scenario. Our marine anticancer program is using the sea to develop new agents with activity in resistant solid tumors and to identify new cellular targets for therapeutic intervention. This review describes the integration of different pharmacogenomic tools in the development of Yondelis™, Aplidin^® and Kahalalide F, three marine-derived compounds currently in Phase II or III development. Our results are reinforcing the targeted selectivity of these agents and opening the gates for customized therapies in cancer patients in the near future.

Antibody-based therapies for colorectal cancer

The recent successful development of novel monoclonal antibodies that target key components of biologic pathways has expanded the armamentarium of treatment options for patients with colorectal cancer. Two targets in particular--the process of new blood vessel development, or angiogenesis, and the epidermal growth factor receptor and its signaling pathway--are exploited by the newest monoclonal antibodies that are available for use in colorectal cancer patients. This clinical review focuses on the defining role of the two most clinically advanced novel agents, bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA, http://www.gene.com) and cetuximab (Erbitux; ImClone Systems, Inc., New York, http://www.imclone.com), in colorectal cancer.

The role of the epidermal growth factor receptor in breast cancer

Recent trials of drug therapy targeting the erbB receptor HER2 have met with success in breast cancer. The epidermal growth factor receptor or EGFR is a closely related receptor from this same family that is involved in cellular signal transduction and tumor cell growth and survival. Emerging evidence indicates that EGFR is implicated in the development of hormone-resistant breast cancer, and that its activity is intertwined with estrogen receptor. Here, the role of EGFR in breast cancer is reviewed, and data from selected clinical trials of signal transduction inhibition of this cellular target are summarized.

Cutaneous reactions to chemotherapy and their management

International data from 2002 report 10.9 million new cases of cancer and 6.7 million cancer deaths. Chemotherapy is an essential component in the multidisciplinary management of most cancers. Cutaneous reactions to chemotherapeutics are common and may contribute significantly to the morbidity, and rarely to the mortality, of patients undergoing such treatments. Recognition and management of these reactions is important to provide optimal care. This article aims to present the most common cutaneous reactions to frequently used chemotherapies and provides management guidelines. A MEDLINE search from 1966 through June 2005 was conducted to identify reports of common cutaneous toxicities with systemic chemotherapy and their appropriate management. An analysis of our literature search is presented in review form outlining common chemotherapy-related cutaneous reactions and their management, as well as the chemotherapeutics responsible for the cutaneous toxicity. Chemotherapy-related cutaneous toxicity includes generalized rashes such as the spectrum between erythema multiforme and toxic epidermal necrolysis, and site-specific toxicity such as mucositis, alopecia, nail changes, extravasation reactions, or hand-foot syndrome. Most of the toxicity is reversible with chemotherapy dose reductions or delays. Certain toxicities can be effectively treated or prevented, allowing optimal delivery of chemotherapy (e.g. premedications to prevent hypersensitivity, prophylactic mouthwashes to prevent mucositis). Newer non-chemotherapeutic targeted therapies such as epidermal growth factor receptor inhibitors (e.g. gefitinib, cetuximab) may also be associated with cutaneous toxicity and can be distressing for patients. Recent data suggest that skin toxicity associated with these agents may correlate with efficacy. Cutaneous toxicity occurs frequently with chemotherapy and non-chemotherapeutic biologic therapies. Early recognition and treatment of the toxicity facilitates good symptom control, prevents treatment-related morbidity, and allows continuation of anti-cancer therapy.

Kinase mutations in cancer: chinks in the enemyʼs armour?

PURPOSE OF REVIEW

Over the past few years, a revolution has transformed the oncology field. This revolution is characterized by two main features. The first is the introduction of the concept of individualized cancer therapy. The second is the development of drugs targeting molecules selectively altered in tumours. This review analyses these aspects by looking at the role that altered kinases and their inhibitors have played in this historical process.

RECENT FINDINGS

Tumour progression is the result of the sequential accumulation of mutations in genes monitoring the rates of cell birth and cell death. The molecular profiling of cancers has shown that protein and lipid kinases are frequently altered in tumour cells. In most cases, these alterations translate in constitutively active proteins, which are amenable of therapeutic targeting. Intriguingly, even 'established' cancer cells remain somewhat 'addicted' to the deregulated activity of mutated kinases. This feature appears to be the basis for the ability of kinase inhibitors in controlling the development of a number of cancers. The therapeutic efficacy of kinase inhibitors is impaired by the emergence of tumour cells carrying 'resistance' mutations.

SUMMARY

Many oncogenes are mutated kinase genes. In most cases, the mutations result in the constitutive activation of the affected kinase that can be pharmacologically inhibited. Unfortunately, upon treatment with kinase inhibitors, resistant clones develop rapidly, impairing their therapeutic effect. Strategies to overcome resistance are discussed as well as the possibility to target kinases regulating cancer stem cells.

How much can current interventions reduce colorectal cancer mortality in the U.S.?

BACKGROUND

Although colorectal cancer (CRC) is the second leading cause of cancer death in the U.S., available interventions to reduce CRC mortality are disseminated only partially throughout the population. This study assessed the potential reduction in CRC mortality that may be achieved through further dissemination of current interventions for risk-factor modification, screening, and treatment.

METHODS

The MISCAN-COLON microsimulation model was used to simulate the 2000 U.S. population with respect to CRC risk-factor prevalence, screening use, and treatment use. The model was used to project age-standardized CRC mortality from 2000 to 2020 for 3 intervention scenarios.

RESULTS

Without changes in risk-factor prevalence, screening use, and treatment use after 2000, CRC mortality would decrease by 17% by the Year 2020. If the 1995 to 2000 trends continue, then the projected reduction in mortality would be 36%. However, if trends in the prevalence of risk-factors could be improved above continued trends, if screening use increased to 70% of the target population, and if the use of chemotherapy increased among all age groups, then a 49% reduction would be possible. Screening drove most (23%) of the projected mortality reduction with these optimistic trends; however, decreasing risk-factors (16%) and increasing use of chemotherapy (10%) also contributed substantially. The contribution of risk-factors may have been overestimated, because effect estimates could not be obtained from randomized controlled trials.

CONCLUSIONS

Currently available interventions for risk-factor modification, screening, and treatment have the potential to reduce CRC mortality by almost 50% by the Year 2020. However, without action now to further increase the uptake of current effective interventions, the reduction in CRC mortality may be only 17%.

Adjuvant Therapy for Colon Cancer 2005: New Options in the Twenty-First Century

The most effective current regimen for adjuvant treatment of surgically resected stage III colon cancer is the FOLFOX regimen of oxaliplatin, 5-FU and LV for 12 weeks, with a proportional risk reduction of 45% compared with approximately 36% for 5-FU/LV regimens. Infusion regimens of 5-FU with and without LV have been shown to confer equivalent benefit to bolus regimens in reducing the risk of cancer recurrence, but with lesser toxicity profiles. Oral 5-FU prodrug regimens have similarly shown equivalent benefit to bolus regimens, and toxicity comparable to infusional regimens, but with the added convenience over 5-FU infusion therapy. The addition of irinotecan to 5-FU and LV regimens has not demonstrated an advantage compared with 5-FU/LV treatments in the adjuvant setting.

Phase II study of tailored chemotherapy for advanced colorectal cancer with either 5-fluouracil and leucovorin or oxaliplatin and irinotecan based on the expression of thymidylate synthase and dihydropyrimidine dehydrogenase

BACKGROUND

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are essential enzymes for 5-fluorouracil (5-FU) metabolism. In patients with advanced colorectal cancer (ACRC), retrospective studies have shown that low expression levels of TS and DPD correlated with response to 5-FU. We performed a prospective study in which the choice of first-line chemotherapy with either 5-FU or a non-5-FU containing regimen was based on TS and DPD expression.

PATIENTS AND METHODS

Fresh-frozen samples of metastases were obtained from 58 previously untreated patients with ACRC. mRNA expression of TS and DPD was quantified using an RT-PCR assay. Patients with low tumor expression of both TS and DPD received weekly bolus 5-FU/leucovorin (LV) 500 mg/m2 (group A); patients with high TS and/or DPD received 3-weekly oxaliplatin 85 mg/m2 and irinotecan 200 mg/m2 (group B). After progression, cross-over to the alternative regimen was attempted.

RESULTS

Of 53 eligible patients, 31 had tumors with both low TS and low DPD, and were treated in group A. A response was observed in 11 patients [35%; 95% confidence interval (CI) 19% to 54%]. Cross-over to second-line oxaliplatin/irinotecan resulted in a partial response in two out of 16 patients (13%; 95% CI 1% to 38%). In group B, four out of 22 patients responded (18%; 95% CI 5% to 40%), while no responses were observed in 12 patients after cross-over to 5-FU/LV (0%; 95% CI 0% to 28%).

CONCLUSIONS

Prospective selection of 5-FU/LV chemotherapy based on low TS and DPD expression in patients with ACRC did not confirm the high response rates reported in retrospective studies. The procedure of obtaining metastatic tissue and quantitation of enzymes appeared feasible but cumbersome. Before assessing the clinical utility of a predictive marker in a randomized trial, future studies should focus on prospective validation of the assay in a large and well defined population.

Novel approaches to treatment of advanced colorectal cancer with anti-EGFR monoclonal antibodies

The standard treatment of metastatic colorectal cancer (mCRC) is combination of 5- fluorouracil/folinic acid with irinotecan or oxaliplatin-based chemotherapy. Epidermal growth factor receptor (EGFR) is overexpressed in 70%-80% of colorectal cancers (CRC). EGFR overexpression is known to be involved in carcinogenic processes, such as cell proliferation, apoptosis, angiogenesis and metastasis. Monoclonal antibodies targeting EGFR have shown antitumor activity and improved the efficacy of chemotherapy. Cetuximab is a chimeric immunoglobulin (Ig) G1 anti-EGFR monoclonal antibody (MoAb). Several clinical studies have shown cetuximab, either as a single agent or in combination with irinotecan, having promising efficacy in patients with metastatic CRC. Cetuximab with 5-fluorouracil/LV (leucovorin) plus irinotecan or oxaliplatin-based chemotherapy has shown higher response rate and longer time to progression as first-line treatment of mCRC. Currently, there are no data showing that addition of cetuximab would prolong overall survival in randomized studies. Panitumumab, a fully human IgG2 monoclonal antibody, has also shown antitumor activity against EGFR-expressing mCRC with less allergic reaction. Anti-EGFR MoAbs are well tolerated and have limited overlapping toxicities in combination with other cytotoxic drugs. The most common side effect of anti-EGFR MoAb is an acneform skin rash, which is a surrogate marker of efficacy of treatment with MoAbs. In this review, we will discuss the use of anti-EGFR MoAbs in the treatment of mCRC, with focus on cetuximab and panitumumab.

Expression of tyrosine kinase receptors in malignant midgut carcinoid tumors

BACKGROUND

The expression of certain tyrosine kinase receptors (TKR) has been shown to have a prognostic value in many tumor entities. In recent years, inhibitors and monoclonal antibodies directed towards these receptors have been developed. Several have shown antitumoral effects and have been tested in clinical trials. We wanted to investigate whether midgut carcinoid tumors express TKR and therefore would be suitable for clinical trials with TKR inhibitors (TKRI) or monoclonal antibodies.

MATERIAL AND METHODS

Tumor tissue from 36 patients (24 women and 12 men) with a malignant midgut carcinoid tumor was obtained. The tissues were examined with immunohistochemistry, using polyclonal antibodies against platelet-derived growth factor receptor-alpha (PDGFRalpha), platelet-derived growth factor receptor-beta (PDGFRbeta), epidermal growth factor receptor (EGFR) and c-kit. Human BON1 cells were cultivated and stimulated with PDGF-BB. We also present a case report of a patient with a malignant midgut carcinoid tumor who had stabilization of tumor growth during treatment with imatinib.

RESULTS

Immunohistochemical staining for PDGFRalpha in tumor cells showed immunoreaction for the receptor in 13/34 (38%) for PDGFRbeta in 29/33 (88%), and 24/33 (73%) were immunoreactive for EGFR. No tumor tissue showed immunoreaction for c-kit. In tumor stroma PDGFRalpha was expressed in 35%, PDGFRbeta in 94% and EGFR in 9%. We show that human neuroendocrine tumor cells respond to PDGF, indicating that these tumors express functional PDGF receptors.

CONCLUSION

Malignant midgut carcinoid tumors may express three of the four TKR tested in this investigation. Therefore, these tumors might be susceptible for treatment with TKRI or monoclonal antibodies and this should be further explored in clinical trials.

New insights into the molecular pathogenesis of colorectal cancer

Although there have been tremendous advances in the management of colorectal cancer (CRC), there is still a need for improved therapeutic approaches. On a molecular genetic level, CRC is one of the best-understood solid malignancies, and these insights can serve as a foundation for the design of novel targeted therapies. We present new genetic and epigenetic pathways that highlight the heterogeneous mechanisms in CRC pathogenesis, including the roles of the MYH DNA repair gene and of aberrant DNA hypermethylation and imprinting. We then describe some of the successful targeted therapies that inhibit COX2, EGFR, and VEGF as well as potential new targets that have been revealed by studies of molecular genetics.

Is tailored therapy feasible in oncology?

Tailored therapy aims to cure a patient who suffers from a specific disease with an effective and safe drug, based on the complex interactions among patient's characteristics, disease physiopathology and drug metabolism. Genomic and proteomic technologies represent promising new useful tools to understand cancer biology and molecular basis of interindividual differences of anticancer drugs efficacy. Genomic profiling seems to be able to re-classifying cancer into new molecular and prognostic homogeneous subgroups. By individual polymorphisms it is possible to identify the patients at higher risk for severe toxicity from those that may gain benefit from a particular treatment. The clinical use of targeted therapy is hampered by several questions, including: optimal biological dose, availability of surrogate biomarkers predictive of activity, schedule of administration, tumor histotype and stage to treat and modalities of combination with chemo/radiotherapy. In addition, further efforts are needed to improve the reliability of genomic and proteomic technologies. These unsolved issues presently make tailored therapy an open challenge.

Development of Antibodies and Chimeric Molecules for Cancer Immunotherapy

Monoclonal antibodies are among the most rapidly expanding class of therapeutics for cancer treatment. Monoclonal antibodies targeting non-Hodgkin's lymphoma (NHL), Her-2/neu highly expressing metastatic breast cancer, colorectal cancer, acute myelogenous leukemia, and B-cell chronic lymphocytic leukemia (CLL) have received FDA approval. Promising new targets for antibody therapy include cellular growth factor receptors, mediators of tumor-driven neo-angiogenesis, as well as host negative immunoregulatory checkpoints that impede an effective immune response to neoplasia. Antibody efficacy has been increased by genetic engineering to humanize the antibodies and to increase their effector functions including antibody dependent cellular cytotoxicity. Furthermore, antibodies have been armed with cytokines, chemotherapeutic agents, toxins, and radionuclides to augment their efficacy as tumor cytotoxic agents. As a consequence of these advances, 30 years after their first development, monoclonal antibodies have become an important standard approach for the therapy of neoplasia with 19 therapeutic monoclonal antibodies now approved by the FDA including 8 for the treatment of cancer.