International Trial Shows Aspirin Protects Against Colorectal Cancer

A daily dose of aspirin can prevent the occurrence of cancer in people with a genetic predisposition towards Lynch syndrome, a condition which accounts for around five percent of all colon cancers, a scientist told the audience at Europe’s largest cancer congress, ECCO 15 – ESMO 34, the joint 15th European CanCer Organisation (ECCO) and 34th European Society for Medical Oncology (ESMO) Multidisciplinary Congress, September 20 – 24 in Berlin, Germany.

Professor John Burn, from the Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, UK, said that he believed that he and his colleagues might have uncovered a simple way of controlling cancer stem cells, which are essential to the formation of malignant tumors.

The clinical trial, which involved 1071 carriers of the Lynch syndrome mutation in 42 centers worldwide, randomized participants to a daily dose of 600mg aspirin and/or 30g Novelose®, a resistant starch that escapes digestion in the small intestine. “Although there were many reports that aspirin might have a beneficial effect in a range of cancers,” said Prof Burn, “they were from case control and epidemiological studies. We decided that the only way to achieve conclusive proof was to undertake a randomized trial in a high risk population.”

Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is a rare type type of inherited cancer of the digestive tract that increases a patient’s risk of cancer, particularly the colon and rectum. People with Lynch syndrome have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, skin, and prostate. Women carriers also have a high risk of developing endometrial and ovarian cancers.

These patients tend to develop cancer quickly, so the scientists expected to see answers at an early stage. The first results were disappointing, however; at an average of 29 months after randomization the scientists saw no evidence of the benefits of aspirin in the high-risk population studied.

“Our original design allowed for long term post trial follow-up,” noted Prof Burn. “We have managed to track down most of those who completed the trial – around 75% of the original consent cohort – with information extending up to 10 years from randomization. We found that, around four years after randomization, there was a divergence in the incidence of cancers between the aspirin and placebo groups. To date, there have been only six colon cancers in the aspirin group as opposed to 16 who took placebo. There is also a reduction in endometrial cancer. This is a statistically significant result and we are delighted – all the more so because we stopped giving the aspirin after four years, yet the effect is continuing, and is directly correlated with the duration of aspirin use on the trial.”

Although scientists believe that diet is a major factor in the prevention of colorectal cancers, there are no randomized trial data which can prove it, since running proper, controlled trials of diet is extremely difficult. However, there is a strong inverse relationship between colon cancer and how much starch people eat. Resistant starch, after escaping digestion in the upper gut, is fermented in the colon and forms short chain fatty acids, which are powerful anti-cancer agents.

“Our very large colon probably evolved to capture such nutrients from our forefathers’ diets,” explained Prof Burn. “Because we were giving starch as well as aspirin we would also have expected to see a decrease in cancers in the placebo group. However, there could be a number of reasons for this result – perhaps patients didn’t take the starch every day, or that it simply wasn’t resistant enough.”

There were minor problems due to aspirin side effects; out of over 1000 people, 11 in the aspirin group had notable gastro-intestinal bleeds or ulcers as opposed to nine in the placebo group. But this was counter-balanced by fewer strokes and heart attacks in the aspirin group.

The mechanism by which aspirin protects against cancer has yet to be elucidated, but the scientists believe that cancer stem cells are involved. “We do not think that the mechanisms discussed to date are likely to provide an explanation,” said Prof Burn. “For example, the inflammatory enzyme COX2(Cyclooxygenase-2), a protein that acts as an enzyme and specifically catalyzes the production of certain chemical messengers called prostaglandins, is over-expressed in early cancer, but our results suggest an effect that predates the cancer, and may even predate the adenoma which precedes it. We believe that aspirin may have an effect on the survival of aberrant stem cells in the colon. These cancer stem cells are normally resistant to chemotherapy, but if a stem cell mutates but does not reveal its potential until an adenoma is formed, and if aspirin reduced the chances of such cells surviving, this would explain our results.”

The team intends to undertake a further study to see whether a smaller dose of aspirin would have the same beneficial effect or not. “We are planning to ask people with Lynch syndrome to agree to ‘toss a coin’ and take, say, either one or two aspirin tablets per day. Then we can see whether the people on the lower dose have the same protection, with fewer side effects. The problem is that, to have a significant result, this will need about 10 times as many people as we needed for our first trial, but the good news is that everyone gets treated,” said Prof Burn.

For more information:

• Abstract no: 6000, Gastro-intestinal malignancies, colorectal cancer session, Monday 11.00 hrs CEST (Hall 2)

Also read these PubMed abstracts:

• Hua A, Mackenzie GG, Rigas B. The differential cell signaling effects of two positional isomers of the anticancer NO-donating aspirin. Int J Oncol. 2009 Oct;35(4):837-44.
• Barry EL, Sansbury LB, Grau MV, Ali IU, Tsang S, et al. Cyclooxygenase-2 Polymorphisms, Aspirin Treatment, and Risk for Colorectal Adenoma Recurrence--Data from a Randomized Clinical Trial. Cancer Epidemiol Biomarkers Prev. 2009 Sep 15. [Epub ahead of print]
• Lang DL. Aspirin as Colorectal Cancer Adjuvant Therapy. Gastroenterology. 2009 Aug 22. [Epub ahead of print]
• Neugut AI. Aspirin as adjuvant therapy for colorectal cancer: a promising new twist for an old drug. JAMA. 2009 Aug 12;302(6):688-9
• Chan AT, Giovannucci EL, Meyerhardt JA, Schernhammer ES, et al. Aspirin dose and duration of use and risk of colorectal cancer in men. Gastroenterology. 2008 Jan;134(1):21-8. Epub 2007 Sep 26.

Growing Attendance for International GI Cancer Congress Demonstrates Importance and Increased Impact.

The 11th World Congress on Gastrointestinal Cancer, organized by ESMO, the European Society for Medical Oncology, opens today in Barcelona, Spain, with a substantial increase in registered attendees over previous years.

The conference is expected to provide important practice updates and promising new research into the numerous types of cancers that affect the gastrointestinal tract.

“Ongoing study and changing standards in the treatment of gastrointestinal cancers have made it mandatory for clinicians to continually update their knowledge to keep up with advances in the field,” says Congress co-chair Dr. Eric Van Cutsem. “The World Congress on Gastrointestinal Cancer addresses the immediate practice implications of these changes.”

Researchers will present studies indicating prolonged progression-free survival and focusing on the importance of personalized cancer care.

Gastrointestinal cancers include anal cancer, colorectal cancer, esophageal cancer, gallbladder cancer, gastric cancer, liver cancer (hepatoma), pancreatic cancer, and small intestine cancers. The most prevalent of these is colorectal cancer in the Western world and gastric cancer in Eastern World.

Colorectal cancer is a major public health problem in Western countries, with the highest incidence rates in North America, Western Europe, Australia and New Zealand. It is the third most common cancer in both men and women, and the third most common cause of cancer death in both sexes. About 630,000 deaths from colorectal cancer are expected this year worldwide, accounting for 8% of all cancer deaths. Gastric is the second most frequent cause of cancer related mortality, accounting for nearly 800,000 deaths each year worldwide.

Over 400 studies will be presented at the world’s largest GI cancer conference and published in the Annals of Oncology, the official journal of the European Society for Medical Oncology (ESMO), outlining research taking place across the globe. Some of the most important work in the field outlines improved patient outcomes through novel drug therapies including combination therapies and new applications of existing therapies.

Six abstracts have been selected by the congress chairs as “top abstracts”. A common thread of these recognized papers is prolonged progression-free survival, enabling patients to live longer with the disease and with a better quality of life. Moreover, the experts will discuss the changing paradigm in gastrointestinal cancer toward a more personalized treatment approach for patients with gastrointestinal cancers.

Also being recognized at the congress are researchers from developing nations who received grants based on the scientific merit of their submitted work.

The ESMO Conference: 11th World Congress on Gastrointestinal Cancer, developed and managed by Imedex, will be held from 24-27 June at the CCIB convention center in Barcelona. The internationally recognized faculty will include 72 experts, chaired by Mario Dicato, MD of the Luxembourg Medical Center in Luxembourg and Eric Van Cutsem, MD, PhD of the University Hospital Gasthuisberg in Leuven, Belgium. 3,500 people from nearly 100 countries are expected to attend.

Designed to promote a multidisciplinary approach to treatment, the scientific agenda offers targeted sessions for oncology surgeons and nurses as well as a comprehensive range of topics for researchers, gastroenterologists, as well as medical and radiation oncologists.

The conference has received endorsements from leading professional societies and organizations, solidifying the reputation of the Congress as the premier platform for specialists in cancer research, leading oncologists and practicing clinicians to review the state-of-the-art advances in gastrointestinal cancer and share the latest information on its multidisciplinary management. Specialized sessions for nurses, surgeons and young medical oncologists provide enhanced educational opportunities.

The 11th World Congress on Gastrointestinal Cancer Congress is endorsed by:

• The Cholangiocarcinoma Foundation
• ENETS (European Neuroendocrine Tumor Society)
• EONS (European Oncology Nursing Society)
• EORTC (European Organisation for Research and Treatment of Cancer) – GI Tumor Group
• ESO (European School of Oncology)
• ESSO (European Society of Surgical Oncology)
• Europacolon

For more information:

• 11th World Congress on Gastrointestinal Cancer.
• ESMO: The European Society for Medical Oncology

For more information, read these PubMed abstract:

• ESMO Conference: 11th World Congress on Gastrointestinal Cancer, 24-27 June, 2009, Barcelona, Spain. Abstracts. Ann Oncol. 2009 Jun;20 Suppl 7:vii7-127 (Annals of Oncology Online)
• Abstracts of the ESMO International Symposium: 10th World Congress on Gastrointestinal Cancer. June 25-28, 2008. Barcelona, Spain. Ann Oncol. 2008 Jun;19 Suppl 6:vi9-105 (Annals of Oncology Online)
• Koh HC, Page B, Black C, Brown I, Ballantyne S, Galloway DJ. Ectopic pancreatic-type malignancy presenting in a Meckel's diverticulum: a case report and review of the literature. World J Surg Oncol. 2009 Jun 22;7(1):54. [Epub ahead of print]
• Beswick EJ, Reyes VE. CD74 in antigen presentation, inflammation, and cancers of the gastrointestinal tract. World J Gastroenterol. 2009 Jun 21;15(23):2855-61.
• Caracino V, Maggi G, Altobelli S, Lambiase C, Danza C, D'Amico G. Voluminous bleeding stomach GIST: reflections on aetiopathogenesis, diagnosis and therapy. Chir Ital. 2009 Mar-Apr;61(2):255-9.
• Schulze-Bergkamen H, Weinmann A, Moehler M, Siebler J, Galle PR. Novel ways to sensitise gastrointestinal cancer to apoptosis. Gut. 2009 Jul;58(7):1010-24.

Photos courtesy of the American Society of Clinical Oncology

Imatinib mesylate after surgery dramatically reduces risk of cancer returning in patients with gastrointestinal stromal tumors

The U.S. Food and Drug Administration, in late December 2008, approved imatinib mesylate (Glivec®, Novartis AG, Lichtstrasse 35, 4056 Basel, Switzerland and Gleevec®, Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, NJ) for the post-surgery treatment of adult patients following complete surgical removal of KIT (CD117)-positive gastrointestinal stromal tumors (GIST).

The tyrosine kinase inhibitor imatinib mesylate is now the only post-surgery treatment indicated to delay the return of this highly aggressive cancer, filling a major need for GIST patients in the United States. The filing received FDA priority review status in August 2008, with regulatory reviews currently underway in other regions, including the European Union (EMEA) and Switzerland.

Soft Tissue Sarcoma
While most cancers are carcinomas, gastrointestinal stromal tumors (GIST) belong to a group of cancers known as soft tissue sarcomas. These cancers grow from cells of the body’s connective or supportive tissues such as bone, cartilage, tendons, nerves, fat, muscle, synovial tissue, or blood vessels.

A life-threatening disease
GIST is a life-threatening cancer of the GI tract affecting the digestive tract or nearby structures within the abdomen. It is the most common mesenchymal tumor of the gastrointestinal tract originating from cells found in the stomach and small intestine, Interstitial Cells of Cajal (ICCs) or from less differentiated stem cells or precursor cells, known as mesenchymal precurser cells, in the gut wall, which can develop into ICCs.

These Interstitial Cells of Cajal or ICCs are part of the autonomic nervous system , and generally found in the myenteric plexus and nearby areas between the circular and longitudinal layers of the gastrointestinal tract. Their function is to regulate gastrointestinal motility, or peristalsis, which is the autonomic movement of the GI tract to propel food and liquid through the digestive tract through the stomach and intestines.

Incidence
Data concerning the worldwide prevalence of GIST is lacking. But some population based studies estimate the annual incidence to be 4,500 - 6,000 new cases per year in the United Sates (15-20 cases per million population), of which more than 90% are KIT-positive.

Genetics
KIT - also known as CD117 - is a protein that, when mutated, has been identified as one of the major causes of GIST. These mutations result in spontaneous activation of tyrosine kinase domains, providing a constant growth stimulus to the tumor cells.

Many GIST contain mutations in exon 11 and, to a lesser degree, in exons 9, 13 or 16, of the c-kit (KIT) protooncogene coding for C-KIT (CD117). Imatinib mesylate inhibits the activity of several proteins such as KIT.

Some GISTs have a mutation of the platelet-derived growth factor receptor-alpha (PDGFRA) gene. Furthermore, a snall number of GISTs, aproximately 5-15%, have no detectable KIT or gene mutation. This includes most pediatric GISTs and GISTs arising in patients with an inactivation of the neurofibromatosis gene (NF1).

Like most cancers, GIST affects older people. The average age at presentation is 50 to 60 years of age. Children are rarely affected, while familial GIST develops in younger or middle-aged adults.

Difficult to diagnose
Most patients, especially those with smaller tumors, are asymptomatic. Asymptomatic GISTs can be discovered incidentally during endoscopy or laparoscopy as well as during computed tomography (CT). Biopsy and endoscopic ultrasound are generally used for staging. However, because tumors are slow growing and symptoms of GIST are generally not different than other GI complaints such as nausea, vomiting, bleeding, dyspepsia and obstruction, earely detection of the cancer is rather dificult.

Approximately 60% of these tumors occur in the muscular wall of the stomach. However tumors may also develop in the small intestine, colon, rectum, esophagus and other intra-abdominal locations. The likelihood of malignant behavior is dependent on the size of the tumor and its rate of growth. Metastases usually occur within the abdominal cavity and/or the liver.

Treatment options
Early gastrointestinal stromal tumors, or GIST that has not yet metastasized, is often treated initially with surgery to remove the cancer. Unfortunately, the risk of recurrence is high, and GIST remains relatively resistant to chemotherapy and/or radiation therapy. Targeted drugs that inhibit the KIT, such as imatinib mesylate, offer an important approach to treating these cancers. These drug are intended to be given to patients following surgery to help prevent recurrence.

However, in some cases patients with gastrointestinal stromal tumors (GIST) whose disease has progressed or who are unable to tolerate treatment with imatinib mesylate require alternative treatment. Researchers found that sunitinib malate (Sutent®, Pfizer Oncology, Pfizer Inc, 235 East 42nd Street, New York, NY 10017), an orally-available small-molecule multiple receptor tyrosine kinase inhibitor, delayed the time it takes for tumors or new lesions to grow in patients with this tare type of cancer. Specifically, the median time-to-tumor progression (TTP) for patients treated with sunitinib malate was 27 weeks compared to 6 weeks for patients who were not treated.

Established efficacy
The efficacy of imatinib mesylate was established in a clinical trial in which patients received either imatinib mesylate or a placebo for one year after surgical removal of the tumor. The optimal treatment duration is not known.

There were significantly fewer recurrences of GIST in patients receiving imatinib mesylate than in patients who did not. The most frequently reported adverse reactions were diarrhea, fatigue, nausea, swelling of the feet, decreased red blood cell counts, rash, vomiting and abdominal pain.

Recurrence
After initial removal, GIST tumors can return in as many as one of two patients. Recurrent GISTs are often more aggressive than primary tumors, with relapses associated with lower survival rates.

'After surgery, my doctor told me there was a high likelihood that my gastrointestinal tumors would come back. I immediately searched for a possible solution and found the Glivec clinical trial, which aimed to help patients like me,' said Roslyn Fuller, a GIST patient. 'This FDA approval is good news for me and other GIST patients who will now have the option to start treatment with Glivec earlier to help prevent recurrence.'

Phase II study
The approval for this new indication is based on data from an international Phase III trial sponsored by the National Cancer Institute. The study showed a dramatic reduction in the return of GIST after surgery in patients treated for about one year with imatinib mesylate versus placebo.

The FDA regulatory filing for the adjuvant GIST indication was based on data from a Phase III, double-blind, randomized, multicenter, international study of more than 700 GIST patients who had undergone surgery to remove their tumors. The efficacy endpoint of the study was recurrence-free survival (RFS), defined as the time from the date of randomization to the date of recurrence or death from any cause. Participants were randomized to receive either imatinib mesylate 400 mg/day or a matching placebo for one year.

Based on a 14-month median follow up, 91.6% of patients receiving imatinib mesylate remained cancer-free compared with 80.2% of those taking placebo. (30 RFS events out of 359 patients in the imatinib mesylate arm (8.4%) compared to 70 RFS events out of 354 patients in the placebo arm (19.8%) (hazard ratio=0.398 [95% CI: 0.259, 0.610], p<0.0001).'Approval of Gleevec offers health care professionals and patients an important new therapeutic option for patients with this uncommon gastrointestinal disease,' said Richard Pazdur, M.D., director, Office of Oncology Drug Products, Center for Drug Evaluation and Research, FDA. 'It illustrates how the continued study of a once novel drug throughout its product lifecycle can yield new and important uses.'

Revolution in the making
Imatinib mesylate was first approved by the FDA in 2001. It is one of the first drugs in a class of agents that block cellular communications that result in tumor growth. Soon after the introduction of effective molecularly targeted therapies such as imatinib mesylate and sunitinib malate the standard of practice for GIST rapidly changed.

'When Glivec was first approved for the treatment of inoperable and/or metastasized KIT-positive GIST six years ago, it revolutionized the treatment of this life-threatening cancer,' said David Epstein, President and CEO, Novartis Oncology. 'This atest FDA approval means patients can benefit from Glivec earlier in the course of their disease.'

Multiple indications
The drug is now approved for nine indications, including the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (Ph+ CML), Kit (CD117)-positive gastrointestinal stromal tumors which cannot be surgically removed and/or have already spread to other parts of the body (metastasized) and five other rare diseases.

Mode of Action
The effectiveness of imatinib mesylate is based on overall hematological and cytogenetic response rates and progression-free survival in CML, on hematological and cytogenetic response rates in Ph+ ALL, MDS/MPD, on hematological response rates in SM, HES/CEL, on objective response rates and progression-free survival in unresectable and/or metastatic GIST, on recurrence free survival in adjuvant GIST, and on objective response rates in DFSP. Increased survival in controlled trials has been demonstrated only in newly diagnosed chronic phase CML and GIST.

For more information, visit:

• Gleevec Official site
• GSI (GIST Support International) site
• Novartis corporate site.
• Novartis Oncology Medical Services site

Also read PubMed abstracts:

• Mazzola P, Spitale A, Banfi S, et al. Epidemiology and molecular biology of gastrointestinal stromal tumors (GISTs): a population-based study in the South of Switzerland, 1999-2005. Histol Histopathol. 2008 Nov;23(11):1379-86.
• Yan BM, Kaplan GG, Urbanski S, et al. Epidemiology of gastrointestinal stromal tumors in a defined Canadian Health Region: a population-based study. Int J Surg Pathol. 2008 Jul;16(3):241-50.
• Mucciarini C, Rossi G, Bertolini F, et al. Incidence and clinicopathologic features of gastrointestinal stromal tumors. A population-based study. BMC Cancer. 2007 Dec 20;7:230.
• Tryggvason G, Kristmundsson T, Orvar K, et al. Clinical study on gastrointestinal stromal tumors (GIST) in Iceland, 1990-2003. Dig Dis Sci. 2007 Sep;52(9):2249-53.
• Demetri GD, Benjamin RS, Blanke CD, et al. NCCN Task Force report: management of patients with gastrointestinal stromal tumor (GIST)--update of the NCCN clinical practice guidelines. J Natl Compr Canc Netw. 2007 Jul;5 Suppl 2:S1-29; quiz S30.
• Rubió J, Marcos-Gragera R, Ortiz MR, et al. Population-based incidence and survival of gastrointestinal stromal tumours (GIST) in Girona, Spain. Eur J Cancer. 2007 Jan;43(1):144-8.
• Steigen SE, Eide TJ. Trends in incidence and survival of mesenchymal neoplasm of the digestive tract within a defined population of northern Norway. APMIS. 2006 Mar;114(3):192-200.
• Goettsch WG, Bos SD, Breekveldt-Postma N, et al. Incidence of gastrointestinal stromal tumours is underestimated: results of a nation-wide study. Eur J Cancer. 2005 Dec;41(18):2868-72.
• Tryggvason G, Gislason HG, Magnusson MK, et al. Gastrointestinal stromal tumors in Iceland, 1990-2003: the Icelandic GIST study, a population-based incidence and pathologic risk stratification study. Int J Cancer. 2005 Nov 1;117(2):289-93.
• Irving JA, Lerwill MF, Young RH. Gastrointestinal stromal tumors metastatic to the ovary: a report of five cases. Am J Surg Pathol. 2005 Jul;29(7):920-6.
• Wingen CB, Pauwels PA, Debiec-Rychter M, et al. Uterine gastrointestinal stromal tumour (GIST). Gynecol Oncol. 2005 Jun;97(3):970-2.
  Nilsson B, Bümming P, Meis-Kindblom JM, et al. Gastrointestinal stromal tumors: the incidence, prevalence, clinical course, and prognostication in the preimatinib mesylate era--a population-based study in western Sweden. Cancer. 2005 Feb 15;103(4):821-9.
• Tran T, Davila JA, El-Serag HB. The epidemiology of malignant gastrointestinal stromal tumors: an analysis of 1,458 cases from 1992 to 2000. Am J Gastroenterol. 2005 Jan;100(1):162-8.
• Heinrich MC, Corless CL, Demetri GD et al. Kinase mutations and imatinib response in patients with metastatic gastrointestinal stromal tumor. J Clin Oncol. 2003 Dec 1;21(23):4342-9.
• Belics Z, Csapo Z, Szabo I, et al. Large gastrointestinal stromal tumor presenting as an ovarian tumor. A case report. J Reprod Med. 2003 Aug;48(8):655-8.
• Borden EC, Baker LH, Bell RS, et al. Soft tissue sarcomas of adults: state of the translational science. Clin Cancer Res. 2003 Jun;9(6):1941-56.
• Igwilo OC, Byrne MP, Nguyen KD, et al. Malignant gastric stromal tumor: unusual metastatic patterns. South Med J. 2003 May;96(5):512-5.
• Reith JD, Goldblum JR, Lyles RH, et al. Extragastrointestinal (soft tissue) stromal tumors: an analysis of 48 cases with emphasis on histologic predictors of outcome. Mod Pathol. 2000 May;13(5):577-85.

Visit:

• Update in the Management of Gastrointestinal Stromal Tumors (GIST): A Report from ASCO 2007.
• Life Raft Group. Managing Initial Recurrence. Accessed January 2009.
• Z9001: A Phase III Randomized Double-blind Study of Adjuvant STI571 (Glivec®) Versus Placebo in Patients Following the Resection of Primary Gastrointestinal Stromal Tumor (GIST). Accessed January 2009.
• American Cancer Society. Cancer Reference Information. Detailed Guide for Gastrointestinal Stromal Tumors. Key Statistics. Accessed January 2009.
• US Department of Health and Human Services. Agency for Healthcare Research and Quality (AHRQ). Technology Assessment: Report on the Relative Efficacy of Oral Cancer Therapy for Medicare Beneficiaries Versus Currently Covered Therapy, Part 2. Imatinib for Gastrointestinal Stromal Tumors (GISTs) Accessed January 2009.

Also see:

• Full prescribing information for imatinib mesylate.
• CenterWatch drug information for imatinib mesylate.
• Full prescribing information for sunitinib mesylate.
• Highlight of prescribing information for sunitinib mesylate.
• CenterWatch drug information for sunitinib malate.

Order the book:

• Magic Cancer Bullet: How a Tiny Orange Pill May Rewrite Medical History.

Tumor Mutation Predicts Effectiveness of Treatment for Colorectal Cancer

Routine screening of patients with metastatic colorectal cancer (mCRC) for mutations of KRAS, a gene that encodes one of the proteins in the epidermal growth factor receptor (EGFR) signaling pathway, before initiating treatment with EGFr-inhibitors, will cut costs by providing treatment only to those patients who will benefit from the treatment and by helping those who will not benefit avoid unnecessary side effects.

This conclusion is based on an analysis of data presented during the sixth annual Gastrointestinal Cancers Symposium being held in San Francisco, California (January 15-17, 2009) by Dr.Veena Shankaran, MD, and his team from Northwestern University Feinberg School of Medicine, in Chicago, Illinois. These results demonstrate that savings can be realized by customizing therapy in any Gastrointestinal (GI) malignancy using a molecular tests.

European and US incidence
Gastrointestinal (GI) cancers include cancers of the esophagus, stomach, small intestine, colon, rectum, anus, pancreas and liver. More than 270,000 people are diagnosed with Gastrointestinal cancers in the United States every year and more than 135,000 people die from them annually.

In Europe, approximately 370,000 people develop colorectal cancer every year, accounting for 13% of the total cancer burden and an estimated 200,000 deaths. Around a quarter of CRC patients present with metastatic disease and for these patients survival rates areas low as 5%. Approximately 60-65% of mCRC patients have KRAS wild-type tumors.

Carcinogenesis
The epidermal growth factor receptor plays an important role in carcinogenesis and tumor progression of colorectal cancer (CRC), a multi-step process involving the accumulation of molecular alterations in a number of genes and pathways of proliferative cells of the colon.
These molecular alterations lead to a loss of coordination between the processes of cellular proliferation and differentiation . Researchers have observed aberrations in the EGFR signaling pathway in a number of cancers including mCRC. Therefore, the EGFR has now evolved as a relevant target in the treatment of mCRC.

Monoclonal antibodies
Monoclonal antibodies (MoAb), including cetuximab (Erbitux®, ImClone Systems Incorporated, Branchburg, NJ 08876, Bristol-Myers Squibb Company, Princeton, NJ 08543 and Merck KGaA, Darmstadt, Germany), a human antibody against the epidermal growth factor receptor and panitumumab (Vectibix®, Amgen Inc, One Amgen Center Drive, Thousand Oaks, Ca 91320-1799), a fully human IgG2 monoclonal antibody that is highly selective for the epidermal growth factor receptor, inhibit EGFR activity. However, not all colorectal tumors respond, and not all patients benefit from these therapies. Recent discoveries have shown that the KRAS gene, when mutated, confers resistance to cetuximab and panitumumab by circumventing EGFR’s role in the signaling pathway.

In March 2008, the Journal of Clinical Oncology published results from an analysis of the first randomized, controlled clinical trial which showed that mCRC patients with mutated KRAS tumors do not respond to panitumumab monotherapy. Conversely, patients with wild-type KRAS tumors treated with panitumumab had a better response rate and a prolonged progression-free survival (PFS). Compared to best supportive care (BSC) alone, this therapy also had an impact on quality of life (QoL) and disease-related symptoms.

The Role of KRAS
Over twenty year of study has shown that the KRAS gene plays a central role in tumor development, regulating downstream proteins that are involved in proliferation, survival, metastasis and angiogenesis. It serves as a mediator between extracellular ligand binding and intracellular transduction of signals from the EGFR to the nucleus. Researcher identified the presence of activating KRAS mutations as a potent predictor of resistance to EGFR-directed monoclonal antibodies.

Anti-epidermal growth factor receptor (EGFr) therapies work by blocking the activation of EGFr, thereby inhibiting downstream events that lead to cancer cell signaling. However, in patients with tumors harboring a mutated or activated KRAS, the KRAS protein is always turned 'on' regardless of whether EGFr has been activated or therapeutically inhibited. Thus, in patients with mutated KRAS, signaling continues despite anti-EGFr therapy. Mutated KRAS is detected in approximately 40% of CRC tumors.

Long term evidence
Although activating mutations in KRAS correlates with poor response to anti-EGFR antibodies in mCRC, their role as a selection marker had not yet been established in randomized trials. A number of clinical trials have now demonstrated that patients can benefit from the addition of cetuximab to FOLFOX or FOLFIRI regime in the first-line treatment of metastatic CRC (mCRC). However, subsequent correlative analyses of these trials have also shown that this benefit is limited to patients whose tumors have wild type KRAS status by PCR-based testing.

Cetuximab
A study by the Central European Cooperative Oncology Group (CECOG), the CECOG/CORE1.2.001 study, a randomized Phase II trial investigating the influence of KRAS status on the efficacy of cetuximab in combination with FOLFOX or FOLFIRI in the first-line treatment of 117 mCRC patients, provided a response rate (RR) of 53% in patients with KRAS wild-type tumors versus 36% in those with mutant tumors. The study also showed a trend towards improved overall survival (OS) in patients with KRAS wild-type tumors – 24.4 months for patients with KRAS wild-type tumors vs. 16.7 months for patients with KRAS mutant tumors (p=0.057).

‘It is really exciting to see such a consistent efficacy profile for cetuximab in patient populations defined by KRAS mutational status,' commented Prof. Thomas Brodowicz, MD from the University Hospital of Vienna, Austria, lead investigator of the CECOG/CORE1.2.001 study. 'This further highlights the absolute necessity to define mCRC according to the KRAS status of the tumor in order to determine the most effective treatment strategy and to provide patients with the best possible outcomes.’

The results of the CECOG/CORE1.2.001 study support the pivotal cetuximab trials – the randomized Phase III study CRYSTAL, also presented at this meeting, and OPUS recently published in the Journal of Clinical Oncology. Patients receiving cetuximab in the CRYSTAL and OPUS trials who had KRAS wild-type tumors showed similar response rates to those in the CECOG/CORE1.2.001 study, at 59%2 and 61%,3 respectively.

Panitumumab
To further independently evaluate the association of KRAS status seen in a biomarker analysis of a Phase III, randomized, controlled clinical trial (the so-called ‘408’ study) that investigated the treatment effect of panitumumab monotherapy plus Best Supportive Care (BSC) versus BSC alone in patients with mCRC, additional retrospective analyses of all other studies of panitumumab monotherapy in mCRC were performed.

‘These data are consistent with 30 years of biology which indicate that KRAS is a clinically relevant oncogene,’ said Dr Sean Harper, MD., chief medical officer and head of Global Development at Amgen. ‘We believe the data from our panitumumab monotherapy trial indicates that the benefit-risk profile of panitumumab is improved by restricting use to those patients with mCRC whose tumors have wild-type KRAS genes.’

The data showed the relative effect of panitumumab versus best supportive care (BSC) was significantly greater in patients with non-mutated versus mutated KRAS (HR = 0.45 vs. HR = 0.99). Median PFS in patients without the mutation treated with panitumumab plus BSC was 12.3 weeks versus 7.3 weeks, respectively. When the analysis standardized the time to tumor assessment, the median PFS was 16 weeks versus 8 weeks, respectively (HR= 0.49 vs. 1.07). Some of these data were presented for the first time at the European Cancer Conference (ECCO) in September 2007, but a pooled analysis from data including more than 700 patients was presented at the European Society of Medical Oncology (ESMO) in 2008.

Additional endpoints of this analysis examined overall survival by KRAS status and treatment. When the treatment arms were combined (non-mutated vs. mutated) overall survival was longer in patients with non-mutated compared with mutated KRAS (HR = 0.67). No differences in overall survival were observed between panitumumab and BSC in either KRAS subgroup, potentially due to a high rate of crossover from BSC to panitumumab after progression, and similar efficacy of panitumumab in these patients.

In exploratory analyses, colorectal cancer symptoms and
health-related quality of life (HRQoL) outcomes were compared between panitumumab and BSC treated patients using a validated instrument such as the Functional Assessment of Cancer Therapy-colorectal symptom index and HRQoL using the EQ-5D index, and the EORTC-QLQ-C30 Global Health Status. In patients with tumors carrying non-mutated KRAS genes, the analysis demonstrated that in panitumumab treated patients clinically meaningful inferior symptom control and QoL scores could be excluded compared to BSC, and that in fact, a clinically meaningful difference in favor of

Panitumumab was observed at most time points. In contrast, a clinically significant worsening of symptom control and QoL scores could not be excluded in patients with mutated KRAS tumors treated with panitumumab compared to best supportive care (BSC). The United States (U.S.) prescribing information states that the effectiveness of panitumumab as a single agent is based on progression-free survival. However, there is no currently data available that demonstrates an improvement in disease-related symptoms or increased survival with panitumumab.

In the panitumumab-treated group, patients with non-mutated KRAS had on average double the number of panitumumab infusions as patients with mutated KRAS (10.0 vs. 4.9). Additionally, 20 percent of the KRAS evaluable patients had a treatment-related grade 3 adverse event (12 percent mutated vs. 25 percent non-mutated).

New recommendations and opinions
In November 2008 the National Comprehensive Cancer Network (NCCN) announced, updates to their Guidelines on Colon and Rectal Cancers that included the recommendation that a determination of the KRAS gene status of either the primary tumor or a site of metastasis should be part of the pre-treatment work-up for patients diagnosed with metastatic colorectal cancer. Further, the guidelines recommended that EGFr inhibitors, including panitumumab, should only be used in patients with tumors characterized by the wild-type KRAS gene. These updates were prompted by a systematic review of the relevant literature.

Based on similar evidence, the American Society of Clinical Oncology (ASCO), last week released its first Provisional Clinical Opinion (PCO), reflecting the expert consensus based on clinical evidence on the use of KRAS gene mutation testing in patients with metastatic colorectal cancer. Provisional Clinical Opinions are intended to assist physicians in clinical decision-making and identify questions and settings for further research.

To help guide treatment with the anti-EFGR monoclonal antibodies (MoAb), such as cetuximab and panitumumab, the authors of this Provisional Clinical Opinion recommend that all patients with metastatic colorectal cancer who are candidates for anti-EFGR therapy have their tumors tested for KRAS gene mutations. If a patient has a mutated form of the KRAS gene, it recommends against the use of anti-EFGR antibody therapy, based on recent studies indicating this treatment is only effective in patients with the normal (wild-type) form of the KRAS gene. It is estimated that 40 percent of colon cancer patients have the KRAS mutation.

Recent results from phase II and III clinical trials demonstrate that patients with metastatic colorectal cancer benefit from therapy with MoAbs directed against the EGFR, when used either as monotherapy or combined with chemotherapy. Retrospective subset analyses of the data from these trials strongly suggest that patients who have KRAS mutations detected in codon 12 or 13 do not benefit from this therapy.

Five randomized controlled trials of cetuximab or panitumumab have evaluated outcomes for patients with metastatic colorectal carcinoma in relation to KRAS mutational status as no mutation detected (wild type) or abnormal (mutated). Another five single-arm studies have retrospectively evaluated tumor response according to KRAS status.

Researchers analyzed tumors from 587 patients with metastatic colorectal cancer for a mutated KRAS gene to determine which patients will benefit the most from treatment with a combination of chemotherapy and cetuximab. The KRAS gene is involved in the growth of cancer cells. About 30% to 45% of colorectal cancers have a KRAS mutation, which has been shown in previous studies to predict whether patients will benefit from treatment with drugs that block the epidermal growth factor receptor (EGFR), such as cetuximab.

Testing results in considerable savings
Shankaran and his team calculated the cost savings by creating an economic model derived from publicly available lab and drug-cost information and the 2008 estimated incidence of mCRC from the American Cancer Society. Clinical data were drawn from a recent, 2007, study by Van Cutsem and colleagues published in the
Journal of Clinical Oncology investigated the effectiveness of cetuximab in combination with standard FOLFIRI compared with FOLFIRI alone in the first-line treatment of patients with epidermal growth factor receptor (EGFR)-expressing mCRC. The model used by Shankaran did not include the necessary additional costs associated with clinic appointments, infusion visits, and managing toxicity.

Based on the available data, there are an estimated 29,762 new cases of mCRC annually. The costs for screening is estimated to cost $13 million ($452.00/patient). Using the average wholesale price of cetuximab ($4,032.00/loading dose and $2,880.00/weekly dose for a patient of average height/weight) and assuming an average of 24 doses per patient, as seen in the analysis of the CRYSTAL trial, the first study to compare chemotherapy alone with chemotherapy plus cetuximab as the primary treatment for patients with metastatic colorectal cancer, drug cost per patient were estimated to cost $71,120.00.

According to Shankaran, data from studies indicate that the prevalence of KRAS mutations ranges from 35.6% to 42.3% in all patients with metastatic colorectal cancer. An even higher percentage has been recorded in several trials, suggestion KRAS mutations in up to 46% of all patients. Approximately 59% of patients whose tumors did not have a KRAS mutation and who received cetuximab and chemotherapy had a reduction in tumor size, compared with 43% of patients who received only chemotherapy. Patients with tumors with a mutated KRAS gene did not receive any benefit when cetuximab was added to chemotherapy.

With the assumption that patients with mutated KRAS (35.6% of all patients) would not receive cetuximab, theoretical drug cost savings would be $753 million; considering the cost of KRAS testing, net savings would be $740 million.

Benefit for patients
Commenting on the importance of these studies, Jennifer C. Obel, M.D., a gastrointestinal cancers specialist and attending physician at NorthShore University HealthSystem in Illinois, said ‘These studies address a pressing question in cancer care – how can we identify those patients who will benefit from treatment and differentiate them from those who will not?’

Because patients with colorectal cancer who carry KRAS mutations have been shown not to respond to treatment with EGFr-inhibitors, upfront KRAS testing to limit cetuximab therapy to patients with wild-type KRAS tumors can result in drug cost savings if patients with metastatic colorectal cancer undergoes first-line therapy with a cetuximab-containing regimen.

Dr Obel also said ‘In an era when the cost of cancer care continues to increase, the ability to tailor treatment to each patient’s disease could lead to improved outcomes and fewer side effects for patients, and significant cost savings.’

Personalized medicine
‘This study helps us to identify which patients are most likely to benefit from adding cetuximab to treatment,’ said lead author Eric Van Cutsem, MD, PhD, Professor at the University Hospital Gasthuisberg in Leuven, Belgium. ‘KRAS testing in all people with colorectal cancer immediately after diagnosis could help doctors find the best treatment strategies for the individual patient.’

‘Based on available data, we believe that focusing panitumumab treatment on patients with wild-type KRAS tumors will avoid unnecessary adverse events in patients who are unlikely to benefit, maximize response rates and PFS in patients with wild-type KRAS genes, and redirect patients with a mutated KRAS gene to alternative therapies,' Sean Harper explained. 'We are thrilled to be taking a step forward in advancing the field of personalized medicine by being one of the first to realize the clinical potential of the KRAS gene in guiding treatment of advanced colorectal cancer patients.’

‘Personalized medicine is the next frontier in cancer care. Basing cancer treatment on the unique genetic characteristics of the tumor or the individual with cancer will improve patient outcomes and help avoid unnecessary costs and side effects for patients who are unlikely to benefit,’ said Richard L. Schilsky, MD, ASCO president and Professor of Medicine at the University of Chicago Medical Center. ‘Using KRAS testing to guide colorectal cancer treatment is a prime example of where cancer care is heading.’

Emphasizing the importance and the benefits for individual patients, Dr. Wolfgang Wein, MD Executive Vice President, Oncology, Merck Serono, concluded ‘This can help physicians help in the treatment decision-making process. Tailoring treatment for mCRC is now a reality. Through a simple diagnostic test, patients can be provided with a treatment that is most likely to succeed in their tumor type.’

For more information, read:

• Shankaran V, Bentrem DJ, Mulcahy MF, et al. Economic implications of Kras testing in metastatic colorectal cancer (mCRC).2009 Gastrointestinal Cancers Symposium (GICS). Abstract 298. Presented January 17, 2009. General Poster Session E (Poster Presentation).

Also read:

• F. Di Fiore, E. Van Cutsem, P. Laurent-Puig, et al.
  Role of KRAS mutation in predicting response, progression-free survival, and overall survival in irinotecan-refractory patients treated with cetuximab plus irinotecan for a metastatic colorectal cancer: Analysis of 281 individual data from published series. Journal of Clinical Oncology, 2008 ASCO Annual Meeting Proceedings (Post-Meeting Edition). Vol 26, No 15S (May 20 Supplement), 2008: 4035
• E. Van Cutsem, I. Lang, G. D'haens, et al. KRAS status and efficacy in the first-line treatment of patients with metastatic colorectal cancer (mCRC)treated with FOLFIRI with or without cetuximab: The CRYSTAL experience. Journal of Clinical Oncology, 2008 ASCO Annual Meeting Proceedings (Post-Meeting Edition). Vol 26, No 15S (May 20 Supplement), 2008: 2
• Van Cutsem E, Peeters M, Siena S et al. Panitumumab significantly improves progression-free survival in patients with metastatic colorectal cancer. Ann Oncol 2006; 17 (Suppl 6): vi27 (Abstr O-027).
• Van Cutsem E, Nowacki M, Lang I, et al. Randomized phase III study of irinotecan and 5-FU/FA with or without cetuximab in the first-line treatment of patients with metastatic colorectal cancer (mCRC): The CRYSTAL trial. J Clin Oncol (Meeting Abstracts) 2007 25: 4000.

For more information read PubMed abstracts:

• Heinemann V, Stintzing S, Kirchner T, Boeck S, Jung A. Clinical relevance of EGFR- and KRAS-status in colorectal cancer patients treated with monoclonal antibodies directed against the EGFR. Cancer Treat Rev. 2008 Dec 29. [Epub ahead of print]
• Weber J, McCormack PL. Panitumumab: in metastatic colorectal cancer with wild-type KRAS. BioDrugs. 2008;22(6):403-11.
• Amado RG, Wolf M, Peeters M, et al.
  Wild-type KRAS is required for panitumumab efficacy in patients with metastatic colorectal cancer. J Clin Oncol. 2008 Apr 1;26(10):1626-34. Epub 2008 Mar 3.
• Van Cutsem EJ, Oliveira J; ESMO Guidelines Working Group.
  Colon cancer: ESMO clinical recommendations for diagnosis, adjuvant treatment and follow-up. Ann Oncol. 2008 May;19 Suppl 2:ii29-30.
• Van Cutsem EJ, Oliveira J; ESMO Guidelines Working Group. Advanced colorectal cancer: ESMO clinical recommendations for diagnosis, treatment and follow-up. Ann Oncol. 2008 May;19 Suppl 2:ii33-4
• Van Cutsem E, Dicato M, Haustermans K, et al. The diagnosis and management of rectal cancer: expert discussion and recommendations derived from the 9th World Congress on Gastrointestinal Cancer, Barcelona, 2007. Ann Oncol. 2008 Jun;19 Suppl 6:vi1-8. Contact the author.
• Annemans L, Van Cutsem E, Humblet Y, et al.
  Cost-effectiveness of cetuximab in combination with irinotecan compared with current care in metastatic colorectal cancer after failure on irinotecan--a Belgian analysis. Acta Clin Belg. 2007 Nov-Dec;62(6):419-25
• Van Cutsem E, Peeters M, Siena S. Open-label phase III trial of panitumumab plus best supportive care compared with best supportive care alone in patients with chemotherapy-refractory metastatic colorectal cancer. J Clin Oncol. 2007 May 1;25(13):1658-64
• Tappenden P, Jones R, Paisley S, Carroll C. Systematic review and economic evaluation of bevacizumab and cetuximab for the treatment of metastatic colorectal cancer. Health Technol Assess. 2007 Mar;11(12):1-128, iii-iv
• Starling N, Tilden D, White J, Cunningham D. Cost-effectiveness analysis of cetuximab/irinotecan vs active/best supportive care for the treatment of metastatic colorectal cancer patients who have failed previous chemotherapy treatment.
Br J Cancer. 2007 Jan 29;96(2):206-12.

Also read:

• Full prescribing information (USA) Vectibix®
• Vectibix® website.
• Full prescribing information cetuximab.