Medtronic Inc.’s experimental spinal fusion device Amplify didn’t work as well after five years as it did in two-year tests previously reported by the company, according to U.S. regulators weighing whether to approve it for sale.
After two years, surgeries were successful in 61 percent of Amplify patients, compared with 56 percent for those who had standard procedures using a bone graft from the hip, according to a Food and Drug Administration report today. Amplify resulted in successful operations in 44 percent of patients after five years, compared with 35 percent for standard care, the FDA said.
Medtronic, the world’s largest maker of heart-devices, has been trying to reinvigorate growth in its spinal products business, which accounted for 22 percent of the Minneapolis- based company’s $15.8 billion in revenue for its 2010 fiscal year ended in April. Spine division sales grew 3 percent to $3.5 billion last year. Amplify can add as much as $175 million, or 8 cents a share, to earnings in its first year after approval, Leerink Swann analyst Rick Wise said in a research report today.
“The five-year data and subsequent panel discussion should naturally shed more light on the issue, but barring any new breakthrough data, we’d expect the panel to ultimately vote in favor of Medtronic,” Michael Weinstein, a New York-based analyst at JPMorgan Securities, said in a July 20 report. “Amplify should ultimately win FDA approval, with the focus of next week’s panel on safety and the hot button topic being cancer.”
Higher Cancer Rates
After two years, 3.8 percent of Amplify patients had cancer, compared with 0.9 percent on standard surgery. The malignancy rate for Amplify increased to 5 percent after five years, compared with 1.8 percent for traditional grafts.
Outside advisers to the FDA will meet July 27 to evaluate Amplify. The agency generally follows the recommendations of its advisory panels, though it isn’t required to do so.
Medtronic shares rose 29 cents, or less than a percent, to $37.06 at 9:43 a.m. in New York Stock Exchange composite trading. The stock has increased 7.9 percent in the past 12 months.
About 660,000 back surgeries were performed in the U.S. in 2009, according to Millenium Research Group, a medical market research company in Toronto. In spinal fusion surgery, doctors use bone grafts in an area of the spine to lock together, or “fuse,” the area between two or more vertebrae to treat back pain cause by spinal disease and injuries.
Bone Growth Protein
Amplify combines the company’s bone growth protein, called Infuse, with a ceramic device implanted in the spine for posterior spinal fusion through the patient’s lower back. Infuse won U.S. approval in 2002 for anterior fusion surgeries, a lower-back operation performed through an incision in the front of the patient. It is also cleared for dental procedures and for repairing lower leg fractures.
Infuse generates as much as $800 million in annual revenue for Medtronic, with sales unchanged the past two years, Weinstein said.
A standard spinal-fusion procedure requires two surgeries, often done at the same time, Martin Yahiro, Medtronic’s senior director of clinical and regulatory affairs, said in a July 21 telephone interview. First, doctors operate to take a section of hip bone for use as a graft for the second procedure that repairs the spine, he said.
In a two-year study Medtronic used to seek approval of Amplify, patients treated with the device had shorter surgical times, less blood loss, and needed fewer repeat operations compared with those who had the standard procedure, according to results published in July 2009 in theJournal of Bone and Joint Surgery.
After two years, the study found that 3.3 percent of the Amplify patients were diagnosed with cancer, compared with about 1 percent with standard therapy. That difference wasn’t statistically significant, Medtronic spokeswoman Marybeth Thorsgaard said in a July 21 telephone interview.
“At the panel, we will present preclinical and clinical study data, along with expert opinion, that no plausible biological mechanism for cancer induction or promotion has been identified,” Thorsgaard said.
In the 463-patient trial, 96 percent of those treated with Amplify had a successful fusion surgery compared with 89 percent who underwent the standard therapy, the study found. A successful surgery was defined as an operation in which the vertebrae or bones were joined together and stabilized.
Twenty patients in the Amplify group needed a second surgery after the first fusion failed, compared with 36 repeat procedures in the standard therapy group, the study found. Side effects such as patient reports of pain were similar in the two types of procedures.
Amplify’s advantage “seems to boil down to saving 20 minutes in the operating room,” saidRichard Deyo, a spine expert at Oregon Health & Science University in Portland, in a July 21 telephone interview. Complications from the hip bone grafts “should not be trivialized but it’s not clear to me that there is a big problem there.” Deyo was not involved in Medtronic’s study.