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Avastin

Template:Drugbox Bevacizumab (trade name Avastin, Genentech/Roche) is an angiogenesis inhibitor, a drug that slows the growth of new blood vessels. It is licensed to treat various cancers, including colorectal, lung, breast (outside the USA), glioblastoma (USA only), kidney and ovarian.

Bevacizumab is a humanized monoclonal antibody that produces angiogenesis inhibition by inhibiting vascular endothelial growth factor A (VEGF-A).[1] VEGF-A is a chemical signal that stimulates angiogenesis in a variety of diseases, especially in cancer. Bevacizumab was the first clinically available angiogenesis inhibitor in the United States.

Bevacizumab was approved by the U.S. Food and Drug Administration (FDA) for certain metastatic cancers. It received its first approval in 2004, for combination use with standard chemotherapy for metastatic colon cancer.[2] It has since been approved for use in certain lung cancers, renal cancers, and glioblastoma multiforme of the brain.

At one point bevacizumab was approved for breast cancer by the FDA, but the approval was revoked on 18 November 2011.[3][4] The approval for breast cancer was revoked because, although there was evidence that it slowed progression of metastatic breast cancer, there was no evidence that it extended life or improved quality of life, and it caused adverse effects including severe high blood pressure and hemorrhaging. In 2008, the FDA gave bevacizumab provisional approval for metastatic breast cancer, subject to further studies. The FDA's advisory panel had recommended against approval.[5] In July 2010, after new studies failed to show a significant benefit, the FDA's advisory panel recommended against the indication for advanced breast cancer. Genentech requested a hearing, which was granted in June 2011. The FDA ruled to withdraw the breast cancer indication in November 2011. FDA approval is required for Genentech to market a drug for that indication. Doctors may sometimes prescribe it for that indication, although insurance companies are less likely to pay for it.[3] The drug remains approved for breast cancer use in other countries including Australia.[6]

Clinical trials are underway for many other indications including ovarian cancer, pediatric osteosarcoma, and certain non-malignant eye diseases. In the curative setting (adjuvant therapy), clinical studies are underway in breast cancer and lung cancer.

Background

Bevacizumab is a humanized monoclonal antibody, and was the first commercially available angiogenesis inhibitor. Its main action is the inhibition of the function of a natural protein called vascular endothelial growth factor (VEGF) that stimulates new blood vessel formation. Because most malignant tumors are highly dependant on angiogenesis it was expected that Bevacizumab can stop or delay growth of tumors. Bevacizumab binds directly to VEGF to form a protein complex which is incapable of further binding to VEGF receptor sites (which would initiate vessel growth) effectively reducing available VEGF. The Bevacizumab/VEGF complex is both metabolized and excreted directly.

Indications

Colorectal cancer

Bevacizumab was approved by the FDA in February 2004 for use in metastatic colorectal cancer when used with standard chemotherapy treatment (as first-line treatment) and with 5-fluorouracil-based therapy for second-line metastatic colorectal cancer. This recommendation was based on the E3200 trial — addition of bevacizumab to oxaliplatin/5-FU/leucovorin (FOLFOX4) therapy.

In adjuvant colon cancer, data from two large randomized studies have shown no significant benefit and a potential to cause harm in this setting.[7]

It was approved by the EMEA in January 2005 for use in colorectal cancer.

Lung cancer

In 2006, the FDA approved bevacizumab for use in first-line advanced nonsquamous non-small cell lung cancer in combination with carboplatin/paclitaxel chemotherapy. The approval was based on the pivotal study E4599 (conducted by the Eastern Cooperative Oncology Group), which demonstrated a 2-month improvement in overall survival in patients treated with bevacizumab (Sandler, et al. NEJM 2004). A preplanned analysis of histology in E4599 demonstrated a 4-month median survival benefit with bevacizumab for patients with adenocarcinoma (Sandler, et al. JTO 2010); adenocarcinoma represents approximately 85% of all non-squamous cell carcinomas of the lung.

A subsequent European clinical trial, AVAiL, was first reported in 2009 and confirmed the significant improvement in progression-free survival shown in E4599 (Reck, et al. Ann. Oncol. 2010). An overall survival benefit was not demonstrated in patients treated with bevacizumab; however, this may be due to the more limited use of bevacizumab as maintenance treatment in AVAiL versus E4599 (this differential effect is also apparent in the European vs US trials of bevacizumab in colorectal cancer: Tyagi and Grothey, Clin Colorectal Cancer, 2006). As an anti-angiogenic agent, there is no mechanistic rationale for stopping bevacizumab before disease progression. Stated another way, the survival benefits achieved with bevacizumab can only be expected when used in accordance with the clinical evidence: continued until disease progression or treatment-limiting side effects.

Another large European-based clinical trial with bevacizumab in lung cancer, AVAPERL, was reported in October 2011 (Barlesi, et al. ECCM 2011). First-line patients were treated with bevacizumab plus cisplatin/pemetrexed for four cycles, and then randomized to receive maintenance treatment with either bevacizumab/pemetrexed or bevacizumab alone until disease progression. Maintenance treatment with bevacizumab/pemetrexed demonstrated a 50% reduction in risk of progression vs bevacizumab alone (median PFS: 10.2 vs 6.6 months, HR 0.50, p<0.001).

The National Comprehensive Cancer Network recommends bevacizumab as standard first-line treatment in combination with any platinum-based chemotherapy, followed by maintenance bevacizumab until disease progression. Bevacizumab is given as an intravenous infusion every three weeks at the dose of either 15 mg/kg or 7.5 mg/kg. The higher dose is usually given with carboplatin-based chemotherapy, whereas the lower dose is usually given with cisplatin-based chemotherapy.

Breast cancer

In December 2010, the FDA removed the breast cancer indication from bevacizumab, saying that it had not been shown to be safe and effective in breast cancer patients. The combined data from four different clinical trials showed that bevacizumab neither prolonged overall survival nor slowed disease progression sufficiently to outweigh the risk it presents to patients. This only prevented Genentech from marketing bevacizumab for breast cancer. Doctors are free to prescribe bevacizumab off label, although insurance companies are less likely to approve off-label treatments.[8][9] In June 2011, an FDA panel unanimously rejected an appeal by Roche. A panel of cancer experts ruled for a second time that Avastin, the best-selling cancer drug in the world, should no longer be used in breast cancer patients, clearing the way for the U.S. government to remove its endorsement from the drug. The June 2011 meeting of the FDA's oncologic drug advisory committee was the last step in an appeal by the drug's maker. The committee concluded that breast cancer clinical studies of patients taking Avastin have shown no advantage in survival rates, no improvement in quality of life, and significant side effects. Patient support groups were disappointed by the committee's decision.[10]

On October 11, 2011 the U.S. Food and Drug Administration (FDA) announced that the agency is revoking the agency’s approval of the breast cancer indication for Avastin (bevacizumab) after concluding that the drug has not been shown to be safe and effective for that use.

Avastin will still remain on the market as an approved treatment for certain types of colon, lung, kidney and brain cancer (glioblastoma multiforme).[11]

History relating to breast cancer

In 2010, before the FDA announcement, The National Comprehensive Cancer Network (NCCN) updated the NCCN Clinical Practice Guidelines for Oncology (NCCN Guidelines) for Breast Cancer to affirm the recommendation regarding the use of bevacizumab (Avastin, Genentech/Roche) in the treatment of metastatic breast cancer.

In 2008, the FDA approved Bevacizumab for use in breast cancer. A panel of outside advisers voted 5 to 4 against approval, but their recommendations were overruled. The panel expressed concern that data from the clinical trial did not show any increase in quality of life or prolonging of life for patients — two important benchmarks for late-stage cancer treatments. The clinical trial did show that bevacizumab reduced tumor volumes and showed an increase in progression free survival time. It was based on this data that the FDA chose to overrule the recommendation of the panel of advisers. This decision was lauded by patient advocacy groups and some oncologists. Other oncologists felt that granting approval for late-stage cancer therapies that did not prolong or increase the quality of life for patients would give license to pharmaceutical companies to ignore these important benchmarks when developing new late-stage cancer therapies.[5]

On March 28, 2007, the European Commission approved bevacizumab in combination with paclitaxel for the first-line treatment of metastatic breast cancer.[12]

Renal cancers

In certain renal (kidney) cancers, Bevacizumab improves the progression free survival time but not survival time. In 2009, the FDA approved bevacizumab for use in metastatic renal cell cancer (a form of kidney cancer).[13][14] following earlier reports of activity[15] EU approval was granted in 2007.

Brain cancers

The FDA granted accelerated approval of Avastin for the treatment of recurrent glioblastoma multiforme in May 2009.[16] Treatment for initial growth is still in phase III clinical trial.[17]

In the September 2009 issue of the Journal of Clinical Oncology, UCLA researchers reported that Avastin improves response and survival in patients with recurrent glioblastoma in comparison to historical controls.[18] That study also found that it may be useful in the treatment of radiation necrosis, since it reduces edema and mass effect and diminishes blood-brain-barrier leakage.

In a Phase I clinical trial conducted in 2009–2010, John A. Boockvar's team at Weill Cornell Medical College administered bevacizumab intra-arterially directly into the brain tumors of fourteen patients with recurrent glioblastoma multiforme. Results were sufficiently encouraging to propose a Phase II trial of the technique.[19] Preliminary data of a large multicenter trial reported at the ASCO meeting 2013 suggest that patients with newly diagnosed glioblastoma do not benefit from the addition of bevacizumab to chemoradiation therapy. [20]

Investigational uses

Bevacizumab did not meet its primary endpoint of extending overall survival (OS) in a recent phase III trial in unresectable gastric cancer (in combination with paclitaxel / Taxol), but it did demonstrate a positive result in treatment of ovarian cancer.

A study released in April 2009 found that bevacizumab is not effective at preventing recurrences of non-metastatic colon cancer following surgery.[21]

Bevacizumab has demonstrated activity in ovarian cancer,[22][23] and glioblastoma multiforme,[24] a type of brain tumour, when used as a single agent.

In 2010 two phase III trials showed a 27% and 54% increase in progression-free survival in ovarian cancer.[25]

Bevacizumab has been investigated as a possible treatment of pancreatic cancer, as an addition to chemotherapy, but studies have shown no improvement in survival.[26][27][28] It may also cause higher rates of high blood pressure, bleeding in the stomach and intestine, and intestinal perforations.

The drug is also undergoing initial trials as an addition to established chemotherapy protocols and surgery in the treatment of pediatric osteosarcoma[29] and other sarcomas, such as leiomyosarcoma.[30]

Uses in eye disease

Many diseases of the eye, such as age-related macular degeneration (AMD) and diabetic retinopathy, damage the retina and cause blindness when blood vessels around the retina grow abnormally and leak fluid, causing the layers of the retina to separate. This abnormal growth is caused by VEGF, so bevacizumab has been successfully used to inhibit VEGF and slow this growth.

Bevacizumab has recently been used by ophthalmologists in an off-label use as an intravitreal agent in the treatment of proliferative (neovascular) eye diseases, particularly for choroidal neovascular membrane (CNV) in AMD. Although not currently approved by the FDA for such use, the injection of 1.25-2.5 mg of bevacizumab into the vitreous cavity has been performed without significant intraocular toxicity.[31] Many retina specialists have noted impressive results in the setting of CNV, proliferative diabetic retinopathy, neovascular glaucoma, diabetic macular edema, retinopathy of prematurity[32] and macular edema secondary to retinal vein occlusions.

When bevacizumab is used in the treatment of macular degeneration, only tiny and relatively inexpensive doses (compared to amounts used in colon and other cancers) are required. Some investigators believe that bevacizumab at a cost of around $42 a dose is as effective as ranibizumab at a cost of over $1,593 a dose.[33][34]

The primary pharmacokinetic difference between intraocular Bevacizumab and Ranibizumab is the very large difference in systemic half-lives, i.e. 2 hours for Ranibizumab versus 20 days for Bevacizumab. Since Bevacizumab was designed as a cancer treatment, the long systemic half-life is considered to be a positive feature (allowing greater exposure time of the tumor to the drug), while the same long half-life is a negative feature in intraocular treatment, since it has no benefit outside of the eye and may in fact be detrimental. Although the systemic exposure with both drugs is very low, Ranibizumab has a much lower average systemic exposure (area under the curve), so it may be conjectured to have a commensurately lesser chance of systemic adverse events.

The National Eye Institute (NEI) of the National Institutes of Health (NIH) announced in October 2006 that it would fund a comparative study trial of ranibizumab (Lucentis) and bevacizumab (Avastin) to assess the relative safety and effectiveness in treating AMD.[35] This study, called the Comparison of Age-Related Macular Degeneration Treatment Trials (CATT Study), enrolled about 1,200 patients with newly diagnosed wet AMD, randomly assigning the patients to one of four treatment groups.[36] The CATT Study was conducted at 47 clinical sites throughout the United States, following the patients for 2 years.[37] Initial results of the study showing essentially similar outcomes using either drug at one year were formally published after peer review in the New England Journal of Medicine on May 19, 2011.[38] Similar results in this cohort were maintained at two years, with bevacizumab showing non-inferiority to ranibizumab, although a statistically non-significant trend to improved visual outcomes from injections given monthly rather than as required was noted with both drugs.[39]

Drug administration

Bevacizumab is usually given intravenously every 14 days. In colon cancer, it is given in combination with the chemotherapy drug 5-FU (5-fluorouracil), leucovorin, and oxaliplatin or irinotecan. Clinical trials are underway to test an intra-arterial technique for delivering the drug directly to brain tumors, bypassing the blood–brain barrier.[19][40] For treatment of eye diseases it is injected intravitreously.

Concerns

Adverse effects

Bevacizumab inhibits the growth of blood vessels, which is part of the body's normal healing and maintenance. The body grows new blood vessels in wound healing, and as collateral circulation around blocked or atherosclerotic blood vessels. One concern is that bevacizumab will interfere with these normal processes, and worsen conditions like coronary artery disease or peripheral artery disease.[41]

The main side effects are hypertension and heightened risk of bleeding. Bowel perforation has been reported.[42] In advanced lung cancer, less than half of patients qualify for treatment.[43][44] Nasal septum perforation and renal thrombotic microangiopathy have been reported.[45] In December 2010, the FDA warned of the risk of developing perforations in the body, including in the nose, stomach, and intestines.

In 2013, Hoffmann-La Roche announced that the drug was associated with 52 cases of necrotizing fasciitis from 1997 to 2012, of which 17 patients died.[46] About 2/3 of cases involved patients with colorectal cancer, or patients with gastrointestinal perforations or fistulas.


These effects are largely avoided in ophthalmological use since the drug is introduced directly into the eye thus minimizing any effects on the rest of the body.

Costs

In countries with national health care systems (such as the UK and Canada), many of those national health services have restricted bevacizumab on the basis of cost-benefit calculations; in the U.K., for example, the National Institute for Health and Clinical Excellence has taken the position that bevacizumab should not be funded by the NHS because it costs nearly £21,000 per patient but only minimal benefit in many cancers.[47] In 2006 the Scottish Medicines Consortium recommended against the NHS funding Avastin for first-line treatment of metastatic carcinoma of the colon or rectum, due to estimated costs of £24,000 to £93,000 per quality-adjusted life year (QALY).[48]

The addition of bevacizumab to standard treatment can prolong the lives of breast and lung cancer patients by several months, at a cost of $100,000 a year in the United States.[49] For colorectal cancer, Robert J. Mayer wrote in the New England Journal of Medicine that bevacizumab extended life by 4.7 months (20.3 months vs. 15.6 months) in the initial study, at a cost of $42,800 to $55,000.[50] Costs in other countries vary; in Canada it is reported to cost $40,000 CAD per year.[51]

Counterfeit

On Tuesday, February 14, 2012 Roche and its U.S. biotech unit Genentech announced that counterfeit Avastin had been distributed in the United States.[52] The investigation is ongoing, and differences in the outer packaging make identification of the bogus drugs simple for medical providers. Roche analyzed three bogus vials of Avastin and found they contained salt, starch, citrate, isopropanol, propanediol, t-butanol, benzoic acid, di-fluorinated benzene ring, acetone and phthalate moiety, but no active ingredients of the cancer drug. According to Roche, the levels of the chemicals were not consistent therefore whether the chemicals were at harmful concentrations could not be determined. The counterfeit Avastin has been traced back to Egypt and it entered the legitimate supply chains via Europe to United States.[53][54]

See also

References


External links

  • Avastin.com
  • Off Label Uses of Avastin for AMD
  • Avastin-info.com Information for healthcare professionals outside of the US
  • Avastin News provided by insciences organisation
  • NCI Drug Information Summary on Bevacizumab for Patients
  • NCI Drug Dictionary Definition for Bevacizumab
  • NCT00222469 Phase II Clinical Trial of Bevacizumab for Adenocarcinoma of the Pancreas
  • CATT Study Update 3: Avastin vs. Lucentis — To Get Underway by Year's End!
  • NCT00593450 Comparison of Age-Related Macular Degeneration Treatments Trials: Lucentis-Avastin Trial
  • U.S. National Library of Medicine: Drug Information Portal — Bevacizumab
  • NCCN Guidelines For Breast Cancer Updated; Bevacizumab Recommendation Affirmed
  • Avastin Adverse Events Reported to the FDA Adverse Event Reporting System (AERS)

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