Use Of Drug Herceptin In Breast Cancer Treatment Biology Essay


This essay will discuss the following statement, 'All women diagnosed with breast cancer should receive Herceptin'. I will talk about what the drug Herceptin is and how it works, talk about its benefits and drawbacks, before concluding on whether or not I agree with the opening statement. I will begin my essay by outlining what Herceptin is and how it helps battle breast cancer.

Breast cancer is now the most common form of cancer in the UK with around 46,000 new cases diagnosed every year. But over the last decade the death rate has fallen by a fifth. This is due to increased detection and treatment of breast cancer (Cancer Research UK, 2010). Studies have shown that 25% of women with breast cancer have HER2 positive tumours. HER2 is a transmembrane receptor in a group of growth factor receptors (HER1 - HER4). This receptor is responsible for the cell-cell and cell-stroma communication through signalling of Ras/mitogen - active protein kinase and phosphatidylinositol 3 kinase (PI3K)/Akt pathways. These specific signals are involved in cell proliferation, mobility and survival (Dent, 2009). The amplification of the HER2 gene results in the overexpression of the p185HER2 growth factor which occurs in 25% of early-stage breast cancers with a very poor clinical outcome (Konechy and Untch, 1999). Monoclonal antibodies against the HER2 protein have been studied to show their ability to inhibit human cancer cell proliferation that is overexpressed by the HER2 receptors. This specific antibody called trastuzumab was seen to inhibit tumour growth (Slamon, 2001). The antibody, also known as Herceptin, has been shown to improve response rate and duration of chemotherapy and extends survival with HER2 amplified breast cancers by 12 months. Herceptin has shown a response rate of 23% when used as a single agent. But when Herceptin is used along with chemotherapeutic agents such as Paclitaxel an improved clinical response and prolonged survival rate are observe (Konechy and Untch, 1999). Herceptin binds to the extracellular surface of the HER2 receptor. This binding blocks HER2-activated cell signalling, which intern reduces cell proliferation and restores the ability for cells to undergo apoptosis by inhibiting the PI3K/Akt pathway. This allows for increased cellular sensitivity for chemotherapy (Dent, 2009). Herceptin has another mechanism of action, this involves activating monocytic cells to kill the tumour cells by antibody-dependant cell-mediated phagocytosis (ADCP) (Agiannis, 2006). Herceptin has also been shown to have cytotoxic properties which may be due to the activation of antibody-dependant cellular cytotoxicity (ADCC). ADCC is an immunological effect which is due to the activation of natural killer cells that activate the lysis of Herceptin bound cancer cells. Herceptin also suppresses angiogenesis with the induction of antiangiogenic factors and a reduction of proangiogenic factors. In a study using mice with HER2-positive breast cancer, the mice were treated with Herceptin and Paclitaxel. A response was observed which showed a nice concordance between tumour response and a reduction in microvessel density (Valabrega et al, 2007). The next section will go into the details of administering the drug Herceptin to patients with breast cancer.

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Herceptin is recommended for the treatment of women with early-stage HER2-positive breast cancer as well as chemotherapy and in some cases radiotherapy. Women with pre existing cardiac problems such as left ventricular ejection fraction of 55% or less, a history of congestive heart failure, poorly controlled hypertension and other related heart problems. Herceptin is commonly given at 3-week intervals for one year or until the breast cancer comes back (if before the one year period). Also a 1-week regimen is available in some cases. The 3-week regimen of Herceptin gives a dose of 8mg/kg body weight followed by 6mg/kg every 3-weeks for the year. The 1-week regimen gives a starting dose of 4mg/kg followed by 2mg/kg every week for that year. Herceptin is a rather costly drug with a price of £407.40 for 150mg. The costs of these two regimes differ with the 3-week regimen costing £24,600 a year whereas the 1-week costs £28,000 a year (NICE, 2006). Herceptin overall is a very beneficial drug, here are some of its benefits.

The treatment of Herceptin with chemotherapy can show a 1 year survival rate of 79% (Rang et al, 2003). The dosage and regimen of dosage helps with the treatment. The weekly and 3 week treatments help to reduce the size of HER2 positive tumours that have spread from another part of the body and reduce the chance of remission. Although Herceptin's benefits are very important in the survival of women with HER2- positive breast cancer there are some drawbacks of the drug.

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Adverse effects can fall into two categories, cardiotoxicity and infusion-associated symptoms. Cardiotoxicity can occur in 4% of patients receiving Herceptin. Symptoms of this can include dyspnea (breathlessness), coughing, paroxysmal nocturnal dyspnea and peripheral edema (swelling of peripheral tissues). Infusion-associated symptoms are seen during the first infusion of Herceptin. Symptoms such as chills and fevers are seen in up to 40% of patients. Other symptoms include nausea, vomiting, pain, rigors, headache, dizziness, rash and asthenia (Ngan, 2009). Patients that are treated with Herceptin were seen to have a high risk of cardiac dysfunction. This problem was seen in 3% - 7% of patients receiving the drug. But this risk of cardiac dysfunction is justified for the survival of metastatic breast cancer (Seidman, 2002). I will now conclude by referring back to the starting statement.

After researching the breast cancer drug Herceptin I will now be able to make an overall conclusion of the statement, 'All women diagnosed with breast cancer should receive Herceptin'. I neither agree or disagree with this statement as Herceptin shouldn't be given to all women with breast cancer. Herceptin isn't required for all women with beast cancer as there are many types of breast cancer that aren't affected by treatment with Herceptin. Herceptin is effective towards women with HER2-positive early stage breast cancer. Given in a controlled regime and along with chemotherapy, Herceptin can show a 1 year survival rate of up to 79% (Rang et al, 2003). It can help reduce the size of breast tumours and reduce remission rates. A key factor in the production and treatment of Herceptin is down to the cost of the drug. Herceptin is an expensive drug to make and costs £407.40 for 150mg. The highest cost for a year regime of Herceptin is £28,000 (NICE, 2006), and giving this drug to every woman with breast cancer would create a huge cost for the NHS. As well as cost there are also many problems due to side effects and problems that occur after administration of the drug. Cardiac problems such as cardiac dysfunction can be seen in 3% - 7% of women receiving the drug Herceptin (Seidman, 2002). So before the drug is administered cardiac tests must be carried out to make sure the patient is healthy enough to receive the drug. Many other side effects are observed such as dyspnea, coughing, paroxysmal nocturnal dyspnea and peripheral edema. So as before women should be off full health before receiving Herceptin. Finally I believe that the statement given is neither correct not incorrect. If I was to change the statement to make it correct I would say, 'All women diagnosed with HER2 early stage breast cancer should receive Herceptin depending on their health situation.'