Gastrointestinal Cancer

Olszewski and colleagues reviewpreclinical and clinicaldata regarding vascular endothelialgrowth factor (VEGF) inhibitors,with particular attention to thedevelopment of bevacizumab (Avastin)in patients with colorectal cancer.The translation from biologic conceptto clinical proof of concept has beenstriking in its rapidity. However, manyimportant questions remain, and thisstory is only beginning to unfold. Inthis commentary, we will highlightsome of those questions that bear onthe optimal use of VEGF inhibitors inpatients with colorectal cancer.

There are two conventional treatments for clinically resectable rectalcancer. The first is surgery followed by postoperative combinedmodalitytherapy if the tumor is T3 and/or N1/2. The second, if thetumor is ultrasound T3 or clinical T4, is preoperative combined-modalitytherapy followed by surgery and postoperative chemotherapy. Thereare a number of new chemotherapeutic agents that have been developedfor the treatment of colorectal cancer. Phase I/II trials are examiningthe use of new chemotherapeutic agents in combination with pelvicradiation therapy, most commonly in the preoperative setting. Thereis considerable interest in integrating irinotecan (Camptosar) into preoperativecombined-modality therapy regimens for rectal cancer. Basedon these trials, the recommended regimen for patients who receiveirinotecan-based combined-modality therapy is continuous infusionfluorouracil (5-FU), irinotecan, and pelvic radiation. New trials examiningpreoperative combined-modality therapy regimens substitutingcapecitabine (Xeloda) for continuous infusion 5-FU are in progress.

Unresectable pancreatic cancer has few therapeutic options and adismal prognosis. Cyclooxygenase-2 (COX-2) expression is increasedat the RNA and protein levels in most human pancreatic cancers. Thepurpose of this trial was to determine whether the addition of a COX-2inhibitor to chemotherapy was beneficial. To date, 11 patients with inoperablepancreatic cancer have been treated with the combination ofgemcitabine (Gemzar), irinotecan (Camptosar), and celecoxib(Celebrex) at 400 mg orally twice daily. Encouraging pain relief, improvementin performance status, and decreases in CA 19-9 andcarcinoembryonic antigen levels have been observed.

The combination of irinotecan (Camptosar), epirubicin, andcapecitabine (Xeloda) has shown an acceptable toxicity profile. In thisopen-label phase I study, irinotecan was administered IV at a fixeddose of 250 mg/m2 on day 1 in combination with capecitabine at a fixeddose of 1,500 mg/m2 for days 2 to 7 and epirubicin starting at a dose of40 mg/m2 and escalating by 10 mg/m2 in cohorts of three patients forthose with metastatic adenocarcinomas. With the addition of granulocytecolony-stimulating factor (G-CSF [Neupogen]) to the regimen,patients received epirubicin at clinically relevant doses after dose-escalation.Results of the topoisomerase activity will be reported with thefinal results of this phase I study. The dose-limiting toxicity has not yetbeen reached. This combination regimen in patients with upper gastrointestinalmalignancies and breast cancer will be investigated as partof phase II studies, once the dose-limiting toxicity is determined. Theappropriate sequencing of the regimen to maximize clinical efficacywill also be determined.

Variations of fluorouracil (5-FU) therapy have formed the backboneof chemotherapy for advanced colorectal cancer for many years.With the advent of newer agents that often work best with or even requirechemotherapy to optimize their activity, the issue of the optimalschedule and regimen of administration of 5-FU has taken on a renewedimportance. The combination of irinotecan with 5-FU/leucovorinhas consistently improved survival and response rates in comparisonto 5-FU/leucovorin alone. However, the combination also increasesthe toxicity of the treatment, thus resulting in continuing attemptsto improve on the toxicity profile of the combination, while retainingor improving upon the therapeutic outcomes. This article reviewsthe various combinations of irinotecan with 5-FU/leucovorin.

Esophageal cancer frequently expresses cyclooxygenase-2 (COX-2)enzyme. In preclinical studies, COX-2 inhibition results in decreasedcell proliferation and potentiation of chemotherapy and radiation. Wereport preliminary results of a phase II study conducted by the HoosierOncology Group in patients with potentially resectable esophageal cancer.All patients received cisplatin at 75 mg/m2 given on days 1 and 29and fluorouracil (5-FU) at 1,000 mg/m2 on days 1 to 4 and 29 to 32with radiation (50.4 Gy beginning on day 1). Celecoxib (Celebrex) wasadministered at 200 mg orally twice daily beginning on day 1 untilsurgery and then at 400 mg orally twice daily until disease progressionor unexpected toxicities, or for a maximum of 5 years. Esophagectomywas performed 4 to 6 weeks after completion of chemoradiation. Theprimary study end point was pathologic complete response (pCR). Secondaryend points included response rate, toxicity, overall survival, andcorrelation between COX-2 expression and pCR. Thirty-one patientswere enrolled from March 2001 to July 2002. Respective grade 3/4 toxicitieswere experienced by 58%/19% of patients, and consisted of granulocytopenia(16%), nausea/vomiting (16%), esophagitis (10%), dehydration(10%), stomatitis (6%), and diarrhea (3%). Seven patients (24%)required initiation of enteral feedings. There have been seven deathsso far, resulting from postoperative complications (2), pulmonary embolism(1), pneumonia (1), and progressive disease (3). Of the 22 patients(71%) who underwent surgery, 5 had pCR (22%). We concludethat the addition of celecoxib to chemoradiation is well tolerated. ThepCR rate of 22% in this study is similar to that reported with the use ofpreoperative chemoradiation in other trials. Further follow-up is necessaryto assess the impact of maintenance therapy with celecoxib onoverall survival.

Esophageal cancer is a rare but highly virulent malignancy in theUnited States, and adenocarcinoma of the esophagus has had the mostrapid rate of increase of any solid tumor malignancy. Systemic metastaticdisease is present in 50% of patients at diagnosis. In the remaining50% presenting with local regional disease, systemic metastatic diseasewill develop in the vast majority of these patients.

From the results of recent studies, it is likely that multimodality therapy with chemotherapy and radiation treatment may improve the overall outcome of locally advanced upper gastrointestinal (GI) malignancies, including esophageal, gastric, pancreatic, and biliary tract carcinomas. However, more effective, more optimal, and less toxic chemotherapy regimen(s) with concomitant radiotherapy are needed beyond the concurrent continuous-infusion fluorouracil (5-FU) with radiation that is commonly applied in general practice. Epirubicin (Ellence), cisplatin, and irinotecan (Camptosar) are all active cytotoxic chemotherapy agents in upper GI cancers. Two phase I studies were designed to test the tolerability of the combination of radiotherapy with infusional 5-FU, epirubicin, and cisplatin (ECF) or 5-FU, irinotecan, and epirubicin (EIF) in the treatment of locally advanced upper GI malignancies.

The epidermal growth factor receptor (EGFR) plays an importantrole in cell growth, differentiation, and survival. Targeting EGFR inpatients with colorectal cancer has become an important therapeutictool. Recently, a monoclonal antibody against the extracellular domainof the receptor (cetuximab [Erbitux]) has been approved for the treatmentof patients with EGFR-positive metastatic disease refractory toirinotecan (Camptosar)-based therapy. The role of other targeted agentsagainst EGFR, including other monoclonal antibodies as well as inhibitorsof the intracellular tyrosine kinase domain, will also be discussed.

ROCKVILLE, Maryland-The FDA has approved a new indication for Eloxatin (oxaliplatin for injection, Sanofi-Synthelabo)-as a treatment combined with conventional chemotherapy for the postsurgical treatment of patients with stage III colon cancer after complete tumor resection. The drug, as with its previous two US approvals, is to be used in combination with infusional fluorouracil/leucovorin (5-FU/LV). The company noted that the supplemental approval provides the first new adjuvant treatment for colon cancer in more than a decade.

ATLANTA-In a phase III trial of patients who had undergone surgery for rectal cancer, three regimens of fluorouracil (5-FU)-based chemotherapy and radiation therapy achieved similar rates of relapse-free and overall survival, although the three regimens had somewhat differing toxicity profiles.

The authors have presented acomprehensive review of rectalcancer, challenging cliniciansto consider whether some patientsare being overtreated with anymodality including surgical resection,chemotherapy, and/or radiotherapy.Tables 2 and 3 provide an excellentoverview of suggested criteria for decidingbetween polypectomy/observationand radical resection for a cancerconfined to a rectal polyp.

In this issue of ONCOLOGY, Dr.Rothenberger and colleagueshave collated clinicopathologicdata with the theme of local recurrenceand selective use of adjuvanttherapy. They conclude that the datasuggest we continue to overtreat somepatients with rectal cancer. As a generalization,I completely agree withthe authors. However, it is quite difficultto take outcomes data from largenumbers of patients and selectivelyapply the end results to the prospectivemanagement of an individualpatient with rectal cancer in the absenceof highly accurate preoperativestaging.

Adjuvant therapy, almost bydefinition, overtreats patients.It is the holy grail of those ofus involved in adjuvant therapy to definethe patients who are going to failso that we can decrease the incidenceof tumor recurrence and avoid givingadditional therapy to patients who havebeen cured by their primary treatment.

The definition of overtreatment of rectal cancer is controversial,and thus it is difficult to accurately quantitate its prevalence. All componentsof rectal cancer treatment are associated with significant potentialfor morbidity and dysfunction that may have a negative impacton the patient’s quality of life. No one would disagree with the tenetthat overtreatment should be avoided whenever possible. Despite thatconsensus, little attention is given in the literature to the issues ofovertreatment of rectal cancer. This review article presents a varietyof clinical scenarios and summarizes available data demonstratingthat overtreatment of some patients with rectal cancer is occurring ona regular basis. It is hoped that this will stimulate clinicians to criticallyreview their own practices to eliminate such overtreatment. Developmentof new clinical trials to determine whether current practiceguidelines are promoting overtreatment of selected rectal cancer patientsis proposed.

Pemetrexed (Alimta) shows single-agent activity in advancedcolorectal cancer. In two phase II studies in which patients receivedpemetrexed at 600 mg/m2 or 500 mg/m2 as first-line treatment for metastaticdisease, objective response rates were 15.4% and 17.2%.

Gastric cancer is a major clinical challenge, with poor overall prognosisand limited life expectancy for patients with advanced disease.Even with surgery and other modalities, palliation is often difficult.Improvement of response rates has evolved with the development ofstandard regimens and those incorporating newer chemotherapy agents,such as oral fluoropyrimidines, the taxanes, camptothecins, novel platinums(eg, oxaliplatin [Eloxatin]), and antifolates (eg, pemetrexed[Alimta]). Ongoing trials with these regimens aim toward improvingsurvival, as well as improving the safety profile. It is hoped that in conjunctionwith molecular research in the pathogenesis of gastric cancerand development of targeted therapies in this disease, these trial datamight lead to the evolution of treatment strategies that could prove effective.

Single-agent gemcitabine (Gemzar) is the standard of chemotherapyfor advanced pancreatic cancer, with no phase III trials to date havingshown significantly improved survival with gemcitabine-based combinationsvs single-agent treatment. The multitargeted antifolate agentpemetrexed (Alimta) shows synergistic effects in vitro in combinationwith gemcitabine, and activity and good tolerability when used as singleagenttreatment in advanced pancreatic cancer. In a phase II trial inpatients with advanced pancreatic cancer, the combination ofgemcitabine at 1,250 mg/m2 on days 1 and 8 plus pemetrexed at 500mg/m2 on day 8 after gemcitabine every 21 days resulted in a mediansurvival of 6.5 months and a 1-year survival rate of 29%. Neutropeniawas the primary toxicity, with grade 4 toxicity in 51% of patients. Thepromising results of this trial prompted the initiation of a phase IIItrial comparing gemcitabine at 1,000 mg/m2 on days 1, 8, and 15 every28 days vs the 21-day gemcitabine/pemetrexed regimen given with vitaminsupplementation in patients with pancreatic cancer. The primaryoutcome measure was overall survival, with secondary measures includingresponse rate, progression-free survival, and quality of life.While an increase in response and time to progression was reported forthe gemcitabine/pemetrexed combination, there were no significantdifferences in survival between treatment arms.

The 30 reports in this special supplement to Oncology News International represent highlights of ongoing major clinical trials and new research presented at ASCO 2004 regarding state-of-the-art chemotherapeutic management of gastrointestinal and other cancers. Important developments in capecitabine as adjuvant therapy, novel targeted agents, and new combinations are discussed.

WASHINGTON-The 2004 US Surgeon General’s report on the health risks of smoking adds five cancers to the list of diseases caused by cigarettes-acute myeloid leukemia, and stomach, pancreatic, cervical, and kidney cancers. Other newly

Dr. O’Connell has done a remarkablejob of discussingmodalities available for patientswith intermediate- to high-riskfully resected large bowel malignancies.Indeed, the title “Current Statusof Adjuvant Therapy for ColorectalCancer” is an underestimate of thearticle’s contents, as he nicely detailsthe past development of standard-ofcareadjuvant (and neoadjuvant, whenappropriate) treatments as well. As isclearly pointed out in the article, adjuvanttherapy works. Adding fluorouracil(5-FU) with or without radiationto surgery already saves thousandsof lives each year, and the enticing possibilityof throwing newer chemotherapeuticagents (eg, oxaliplatin)and/or targeted therapies (bevacizumab[Avastin]) into the mix makespotential future successes even greater.

The manuscript written by Drs.Hoff, Ellis, and Abbruzzese isan outstanding overview of thedevelopment, mechanism of action,and key clinical data for bevacizumab(Avastin) and cetuximab (Erbitux).Over the past several years,the landscape for treating patients withcolorectal cancer has changed dramaticallywith the inclusion of irinotecan(Camptosar), oxaliplatin (Eloxatin),and capecitabine (Xeloda). Then, beforewe can even catch our breath,along come cetuximab and bevacizumab.The next several years will befocused on testing these agents in avariety of clinical trial settings to optimizetheir use for patients with colorectalcancers. Three issues come tomind after reviewing the Hoff et almanuscript: (1) semantics, (2) awkwardUS Food and Drug Administration(FDA) indications, and (3) money.

Adjuvant therapy with chemotherapy and/or radiation therapy inaddition to surgery improves outcome for patients with high-risk carcinomasof the colon or rectum. For colon cancer, fluorouracil (5-FU)combined with leucovorin is a current standard of care that improveslong-term survival. A recent European trial (MOSAIC) has documentedsignificant improvement in 3-year disease-free survival when oxaliplatin(Eloxatin) was added to infusional 5-FU and leucovorin in the FOLFOXregimen. Two US cooperative group trials will evaluate the addition ofantiangiogenesis therapy with bevacizumab (Avastin) to chemotherapy.A third trial will evaluate FOLFOX, irinotecan (Camptosar) combinedwith infusional 5-FU and leucovorin (FOLFIRI), and the sequentialuse of FOLFOX followed by FOLFIRI. In rectal cancer, postoperative5-FU–based chemotherapy combined with irradiation can improve bothlocal tumor control and survival. The German Rectal Cancer Grouphas recently reported that preoperative combined-modality therapy isless toxic and more effective in preventing local tumor relapse comparedto similar treatment given postoperatively. A coordinated pair ofcooperative group clinical trials will evaluate oral capecitabine (Xeloda)as a radiation enhancer in the preoperative setting, and the FOLFOXand FOLFIRI regimens compared to 5-FU and leucovorin followingsurgery. Predictive and prognostic molecular markers will be studiedin these new adjuvant therapy clinical trials for both colon and rectalcancer with the goal of developing future regimens tailored to individualpatients. There has been a recent and dramatic increase in thepace of drug development for colorectal cancer which holds promise tofurther improve curative therapy as part of a multidisciplinary approachin the surgical adjuvant setting.

The treatment of colorectal cancer has undergone enormous changesin the past decade. From a disease with a single treatment option (ie,fluorouracil, a modestly effective drug), the treatment options haveevolved to include at least five new classes of antineoplastic agents.Among the considerable number of recently approved drugs, two aremonoclonal antibodies and are the testing ground for our rapidly emergingknowledge about cancer cell biology. Cetuximab (Erbitux) targetsthe epidermal growth factor receptor, an important molecule involvedwith cell cycling, survival, invasion, and metastasis. Bevacizumab(Avastin) neutralizes the vascular endothelial growth factor, blockingits ability to activate its receptor on the endothelial cells. The developmentof both antibodies resulted from decades of research in molecularand cell biology, as well as preclinical and clinical studies, and signalsa new paradigm where the tumor cells’ own unique features areexploited in a rational way.

In the “Current Status of AdjuvantTherapy for Colorectal Cancer,”Dr. O’Connell provides importanthighlights of historical and recent developmentsin adjuvant treatment forcolon and rectal cancer. In addition,he provides insight into the future directionsof research for adjuvant therapyof cancer of the colon and rectum.As the review is thorough, wewould like to expand upon a coupleof areas including lymph node evaluation,changes to the staging system,and the use of molecular prognosticand predictive markers in futurestudies.

Drs. Whisenant and Venookhave provided us with a summaryof the role of hepaticarterial infusion (HAI) chemotherapyfor patients with metastatic colorectalcancer. In their abstract they state thatthere is confusion about whether HAIfor unresectable liver metastases isuseful, because European studies havebeen negative; they go on to say thatthe work in adjuvant therapy hasmixed results. I would like to offersome different interpretations.

Drs. Hoff, Ellis, and Abbruzzesehave provided a thoroughand useful overview of thecurrent status of the two new monoclonalantibodies, cetuximab (Erbitux)and bevacizumab (Avastin), that haverecently become available for the treatmentof colorectal cancer.

In the past 5 years, the treatment ofmetastatic colorectal cancer hasseen unparalleled advances. Medianoverall survivals reported inphase III trials have almost doubledand are poised to break the 2-yearbarrier very soon, perhaps as early asthis year. This has been made possiblethrough the introduction of a varietyof active agents into the treatmentof this disease.

Colorectal cancer is the second most common cause of cancerrelateddeath in the United States. Approximately 30% to 40% of patientswith colorectal cancer have locoregionally advanced or metastaticdisease on presentation and cannot be cured with surgical therapy.After many years without significant change, systemic therapy forcolorectal cancer is rapidly evolving. The past decade has seen the introductionof new chemotherapeutic agents such as irinotecan(Camptosar), oxaliplatin (Eloxatin) and the oral 5-FU prodrugcapecitabine (Xeloda). Combination studies of these new agents withthe standard 5-FU/leucovorin have extended median survival in patientswith advanced colorectal cancer for up to 21 months. In addition,targeted agents with activity in colorectal cancer have emergedand are promising. This article reviews the current treatment recommendationsfor patients who present with advanced colorectal cancer.Survival in patients with advanced colorectal cancer is on a positivetrajectory. The hope that some patients with advanced disease will belong-term survivors (even without surgery) appears to be within therange of possibility.

The past decade has given rise toan explosion of rationally designed,molecularly targetedtherapeutic agents. The epidermalgrowth factor receptor (EGFR) hasserved as the principal platform forthe development of such novel targetedtherapies, resulting in a paradigmshift in the treatment of a vast array ofsolid malignancies. Damjanov andMeropol have provided a comprehensiveand insightful overview of the roleof EGFR-directed therapeutics in colorectalcancer. They have chosen tofocus their discussion on the compoundsthat are furthest along in clinicaldevelopment and, hence, havereviewed the monoclonal antibodiescetuximab (Erbitux), ABX-EGF, andEMD 72000, as well as the small-moleculetyrosine kinase inhibitors gefitinib(Iressa) and erlotinib (Tarceva).