In the long standing debate over advanced, potentially more expensive, treatments for early-stage prostate cancer, a new study has recently been published in which five year outcomes data has been collected and reviewed for patients receiving CyberKnife prostate cancer treatment. As one of the early and most commonly treated indications on this platform, clinicians, patients, and professional societies have been long awaiting longer term outcome data. While the study, published in Radiation Oncology in January 2011, indicated that the therapy is both safe and effective based on a sample size of 41 low-risk prostate cancer patients, the study references the ideal need for larger and multi-center trials to continue to examine clinical outcomes.
Also noted in the study were a number of other trials slated to release five year outcomes data in the near future, run through a range of other early CyberKnife adopter institutions. Overall, there remains a lack of comparative data to put these treatment outcomes data into perspective, but this is often the case in radiation therapy. Furthermore, as these additional studies progress and the data mature, it is likely the industry will face a growing pool of data upon which to evaluate these treatments.
Meeting on January 20th, the Peripheral and Central Nervous System Drugs Advisory Committee of the FDA met to discuss potential approval for Amyvid, a novel radiotracer used to image beta amyloid plaque in the brain. Manufactured by Eli Lilly, Amyvid (florbetapir) is a PET radiotracer which binds to beta amyloid plaque, identified as an indicator of the progression of Alzheimer's disease. The Committee voted not to fully approve the new radiotracer, but rather, to give conditional approval should the manufacturer provide a sufficient training program for readers. Previous studies demonstrated significant variation in readers' ability to extract and interpret data, resulting in a high false-positive rate. The FDA is not calling for more research trials, but rather, that once a training program has been developed, the FDA will likely approve the radiotracer.
To date, the use of PET for neuroimaging has previously been challenging due to the lack of brain-specific radiotracers given existing limitations of using FDG-glucose. High metabolism in the brain renders standard glucose-based imaging unreliable, and PET has thus far been used primarily for oncologic imaging. Amyvid avoids this setback by binding directly to beta amyloid plaque, rather than tracking a specific metabolic process. While Amyvid will not likely be able to definitively diagnose Alzheimer's disease, it can confidently rule it out in favor of other neurodegenerative disorders.
While the availability of Amyvid marks an important step in the evolution of PET imaging to assess myriad neurodegenerative diseases, there is still uncertainty within the medical field regarding the value of detecting precursors to Alzheimer's disease. Without a valid treatment plan, questions remain as to the anxiety placed on the patient and their family in knowing that Alzheimer's is potentially impending. Confidently ruling out Alzheimer's can redirect physician attention to other diseases but detection of beta amyloid plaque does not always indicate Alzheimer's will be present. However, conditional approval of Amyvid and more widespread use of the neuro PET imaging agent can help to further answer these questions and determine an appropriate course of action.
Two-year trial results for Cook Medical's drug-eluting peripheral stent, Zilver PTX, were presented last week at the 23rd Annual International Symposium on Endovascular Therapy meeting in Miami Beach, FL. These findings follow the positive 12-month data presented at TCT in September of last year. The trial, which enrolled 478 patients with symptomatic, above-the-knee femoropopliteal disease, randomized patients to either treatment with the Zilver PTX stent or balloon angioplasty. Patients who experienced suboptimal angioplasty results (120) were then randomized a second time and treated with the Zilver PTX or the Zilver bare metal stent (BMS).
Expanding on the original Zilver bare-metal platform, the Zilver PTX represents the first drug-eluting stent of its kind. Although the self-expanding nitinol stent employs Paclitaxel, the drug used in the coronary drug-eluting stent (DES), TAXUS, it differs from coronary stents in that it is polymer-free, making it specially designed for use in the peripheral arteries.
In October, 12-month data showed that 90 percent of patients treated with the Zilver PTX achieved the safety endpoint--survival, free from amputation--versus 83 percent in the angioplasty group. These results dropped to 87 percent for the Zilver PTX group at 24 months. At both 12 and 24 months, the primary efficacy endpoint evaluated the patency rate for patients undergoing angioplasty or Zilver PTX in either randomization group. At 12 months in the first randomization group, the Zilver PTX, which displayed 83 percent patency, outperformed angioplasty, which only showed 33 percent patency. This trend continued to hold true for the second randomization group, with the Zilver PTX obtaining 90 percent patency versus 73 percent patency in the BMS group. At 24 months, the Zilver PTX continued to show positive outcomes, achieving 75 percent patency against angioplasty (for which 24-month data was unavailable), and 81 percent patency for the second randomization compared to the BMS group's 63 percent patency rate.
For Cook Medical, which hopes to receive FDA approval for the Zilver PTX stent in the near future, these findings show great promise for a strong market entrance and potentially beyond. As the first of its kind amidst a flurry of vascular devices released in recent years, the Zilver PTX's true market potential is not yet known. However, it could play a significant role as a standalone therapy. This is particularly true given the fact that, thus far, physician preferences, paired with the high costs of individual devices, have complicated cost-effective device management for many hospital administrators. To date, Cook has submitted its application to the FDA and is projecting approval in the next six to 12 months. Technology Insights will continue to track trial results and updates on this device.