Genzyme Corp. posted findings from a large, multicentre, observational study that investigated the long-term durability of Carticel (autologous cultured chondrocytes) in patients who had pain and functional impairment from defects in the articular cartilage of their knee. These findings revealed that almost 90 per cent of patients treated with Carticel who experienced improvement in knee function at an early follow-up, sustained their improvement for up to almost 10 years.

"We knew that autologous chondrocyte implantation (ACI) worked for select patients, but did it last?" said Allen Anderson, MD, (Nashville) a leading orthopaedic surgeon in the field of sports medicine who presented the data at the medical meeting. "These data suggest that the ACI technique not only works, but when it works, the results will last for a long time. Similar results of long term durability had been previously reported by Lars Peterson, M.D., but this multicentre experience suggests that sustainable results can be reproduced by others."

The objectives of the study were to determine if a patient's improvement assessed at an early timepoint, defined as 1 to 5 years (mean 4.6 years) after Carticel implantation, could be sustained at a much later time point defined as 6 to 10 years.

Seventy-two patients were enrolled from 35 different centres across the US. All patients enrolled had low functional scores (overall condition score of 3.4 points on the Modified Cincinnati Knee Rating System). Patients were young (mean age of 37 years) and had moderate to large lesions (mean lesion size of 4.3 cm2) on the femoral chondyles (Lateral Femoral Chondyle, Medial Femoral Chondyle and Trochlea) and most patients had undergone at least one previous treatment for their cartilage injury. At their early follow-up, 75 per cent of all patients experienced significant improvement in their knee function (mean improvement of 4.3 in overall condition). Of those patients, 87 per cent sustained improvement at the later follow-up time point.

"Long-term durability of Carticel had not been evaluated in the United States and there was a critical need to determine if Carticel patients experienced sustained improvement," said Leanna M. Caron, vice president and general manager, Genzyme Biosurgery, the division that manufactures and commercializes Carticel. "This study demonstrates both the durability and value of Carticel and leads the field to conclude that a vast majority of this patient population maintained improvement years following their initial procedure."

Also at the AAOS meeting, a separate study conducted at the Brigham and Women's Hospital in Boston, Mass., Dr Tom Minas reported the findings of a study that compared the results of ACI following a marrow stimulation technique versus no significant treatment (including simple debridement) performed on the same cartilage defect. The results indicate that marrow stimulation techniques may compromise the successful outcome of future ACI. Investigators collected data from 329 consecutive patients treated with Carticel for large and multiple defects (4.8 cm2 per lesion and 8.7 cm2 per patient) and had at least two years follow-up. They concluded that patients who had a previous marrow stimulation technique and were subsequently treated with ACI were three times more likely to fail than patients who had not undergone a marrow stimulation technique prior to treatment with ACI.

"The data show that in this patient population marrow stimulation techniques like microfracture are not benign and can compromise a patient's ability to benefit from a subsequent treatment with ACI, effectively limiting their future treatment options," said Tom Minas, MD, an internationally renowned orthopaedic surgeon for his extensive work in the field of Cartilage Repair and principal investigator in this study. "Orthopaedic surgeons should reconsider using marrow stimulation techniques as first-line treatment for patients with larger chondral lesions. These techniques should be reserved for patients with smaller defects, in younger patients, where a good result is more predictable".

More than 14,000 patients in the United States have had Carticel implants. Carticel is used by orthopaedic surgeons to treat patients who have clinically significant articular cartilage lesions on the thigh bone part of the knee caused by acute or repetitive trauma that have not responded to a prior cartilage repair procedure. Carticel should only be used in conjunction with debridement, placement of a periosteal flap and rehabilitation. The independent contributions of the autologous cultured chondrocytes and other components of the therapy to outcome are unknown. Carticel employs a unique process to grow a patient's own cartilage cells for implantation to correct certain types of damage. The treatment starts when an orthopaedic surgeon trained in the use of Carticel provides Genzyme with a biopsy of healthy cartilage taken from a patient's knee in an arthroscopic procedure. Technicians at Genzyme's cell culture laboratory in Cambridge, MA, use proprietary methods to grow millions of cells from this biopsy. The cells are then delivered to the hospital, where the surgeon implants them into the patient's knee defect in a surgical procedure.

Carticel was the first cell therapy to be approved by the FDA. First introduced in March of 1995, Carticel received accelerated approval from the FDA in August of 1997 after the FDA instituted specific cell therapy guidelines. Under accelerated approval, the FDA required Genzyme to conduct confirmatory post-marketing clinical studies. Genzyme successfully completed the confirmatory studies and, in June of 2007, the FDA deemed the commitment satisfied.

Carticel is for autologous use and is indicated for the repair of symptomatic cartilage defects of the femoral condyle (medial, lateral or trochlea), caused by acute or repetitive trauma, in patients who have had an inadequate response to a prior arthroscopic or other surgical repair procedure (e.g., debridement, microfracture, drilling/abrasion arthroplasty, or osteochondral allograft/autograft).