Date Published: 28 April 2011
Avastin and Lucentis equally effective for treating age-related macular degeneration (AMD)
Age-related macular degeneration (AMD) is the leading cause of vision loss (one of many disorders of the human visual system) and blindness in older Americans. In its advanced stages, the wet form of AMD spurs the growth of abnormal blood vessels, which leak fluid and blood into the macula and obscure vision. (The macula is the central portion of the retina that allows us to look straight ahead and to perceive fine visual detail. Accumulation of fluid and blood damages the macula, causing loss of central vision. AMD can severely impede mobility and independence).
Recently announced results from the first year of a two-year clinical trial conducted in the United States suggest that the drug Avastin, which is approved in the USA to treat some cancers and is commonly used off-label to treat age-related macular degeneration, is as effective as the Food and Drug Administration-approved drug Lucentis for the treatment of age-related macular degeneration.
" Over 250,000 patients are treated each year for AMD, and a substantial number of them receive Avastin. Given the lack of efficacy data regarding Avastin for AMD treatment, the NEI had an obligation to patients and clinicians to conduct this study," said Paul A. Sieving, M.D., Ph.D., director of the US-based National Institutes of Health (NEI) who funded the recent study.
Genentech, the maker of both drugs, originally developed Avastin to prevent blood vessel growth that enables cancerous tumors to develop and spread. In 2004, the FDA approved Avastin for the systemic treatment of metastatic colon cancer. Genentech later developed Lucentis, derived from a protein similar to Avastin, specifically for injection in the eye to block blood vessel growth in age-related macular degeneration.
In 2005, two Genentech-sponsored clinical trials established Lucentis as highly effective for the treatment of wet age-related macular degeneration. During the year between the announcement of the trial results and the release of Lucentis, ophthalmologists began injecting age-related macular degeneration patients with low doses of Avastin, due to its similarity to Lucentis and its availability. The FDA has not licensed Avastin for the treatment o fage-related macular degeneration. Many physicians observed a beneficial treatment effect and Avastin's use grew rapidly despite the lack of data on safety, efficacy and dosing from randomized clinical trials to support its use. Ophthalmologists used Avastin primarily as needed, or pro re nata (PRN), when there was evidence of active disease. The FDA approved Lucentis in 2006. However, most clinicians adopted PRN dosing for Lucentis, which was a departure from FDA-approved labeling and the monthly dosing schedule evaluated in the Genentech-sponsored clinical trials. It was not known if PRN dosing would produce the same long term vision benefits that were achieved with monthly administration.
NEI launched the Comparison of AMD Treatments Trials (CATT in 2008 to compare Lucentis and Avastin for treatment of wet AMD. The study has now reported results for 1,185 patients treated at 43 clinical centers in the United States. The patients were assigned randomly and treated with one of four regimens for a year. They received Lucentis monthly or PRN, or Avastin monthly or PRN. Enrollment criteria required that study participants had active disease. Patients in the monthly dosing groups received an initial treatment and then had an injection every 28 days. Patients in the PRN groups received an initial treatment and were then examined every 28 days to determine medical need for additional treatment. PRN groups received subsequent treatment when there were signs of disease activity, such as fluid in the retina. Ophthalmologists involved in patient care did not know which study drug a patient was receiving in order to ensure that the data could not be affected by how they felt about the treatment, e.g. optimistic or otherwise. The main "outcome measure" for CATT was change in visual acuity.
" In addition to the primary finding of equivalence between Lucentis and Avastin for visual acuity, CATT also demonstrates that PRN dosing is a viable treatment option for either of these drugs," said Daniel F. Martin M.D., study chair for CATT and chairman of the Cole Eye Institute at the Cleveland Clinic.
" Substantial visual acuity gains may be accomplished with a lower treatment burden."
Adverse events indicate development or worsening of a medical condition and may, or may not, be causally associated with treatment involved in a clinical trial but are always monitored and reported in trial data. Serious adverse events (primarily hospitalizations) occurred at a 24% rate for patients receiving Avastin and a 19% rate for patients receiving Lucentis. These events were distributed across many different conditions, most of which were not associated with Avastin in cancer clinical trials where the drug was administered at 500 times the dose used for AMD. The number of deaths, heart attacks, and strokes were low and similar for both drugs during the study. CATT was not capable of determining whether there is an association between a particular adverse event and treatment. Differences in serious adverse event rates require further study. It is worth stating that the median age of patients in CATT was over 80 years so the high rate of hospitalizations might be explained at least in part by the fact that chronic or acute medical conditions are generally more common in older populations.
Investigators in the CATT study will continue to follow patients through a second year of treatment. The additional data will provide information about any longer-term effects of the drugs on vision and concerning safety. The FDA has not evaluated data from the CATT trial.
The National Institutes of Health (NIH) The Nation's Medical Research Agency includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov - statement understood to be correct as of publication date.
Institutes of Health (NIH), USA.