FDA approves MACI for the repair of cartilage defect of the knee joint, including osteoarthritis.

MACI
Image courtesy :Vericel Corporation 

VericelCorporation[1], that develops, manufactures, and markets autologous cell-based therapies for patients with serious diseases and conditions made a very important announcement recently that the U.S. Food and Drug Administration (FDA) has approved MACI^® (autologous cultured chondrocytes on porcine collagen membrane) for the repair of symptomatic single or multiple full-thickness cartilage defects of the knee with or without bone involvement in adults.

 As Per FDA “Maci is the first FDA-approved product that applies the process of tissue engineering to grow cells on scaffolds using healthy cartilage tissue from the patient’s own knee.”[2]

The prevalence rate for cartilage defects in knee is reported at 63% in patients undergoing arthroscopies. It is a very common problem in adults and the current definitive treatment is knee replacement surgery.  

MACI is a third-generation autologous chondrocyte implant intended to treat cartilage defects in the knee. The chondrocytes are placed on bio-absorbable porcine derived collagen membrane that is than tailored to the site of defect in the knee.  

Each Maci implant consists of a small cellular sheet containing 500,000 to 1,000,000 chondrocytes per cm2 (about 0.16 square inches). The amount of Maci administered correlates with the denuded bone area, the size of the cartilage defect, and is trimmed to ensure that the damaged area is completely covered. Multiple implants may be used if there is more than one defect.

How MACI acts. courtesy Vericel Corporation

 "The treatment of articular cartilage defects in the knee is challenging because articular cartilage in adults has minimal capacity to repair itself," said David Recker, MD, chief medical officer of Vericel.  "While orthopedic surgeons have long understood that autologous chondrocyte implantation can regenerate cartilage tissue, the previous surgical procedure was technically complex and time consuming, and the indicated patient population was limited.” 

At present the company has its two products in US market, Carticel and Epicel. Carticel is the world’s first cellular product in use by surgeons since 1995. It is created from a patient’s own chondrocytes and has shown to be effective for 4 years. It is currently in use for symptomatic cartilage defects of the femoral condyle (medial, lateral or trochlea) caused by acute or repetitive trauma.

Image courtesy :Vericel Corporation 

Articular cartilage damage is caused by repetitive and acute trauma resulting in swelling, locking and effusion   progressing to debilitating joint pain, dysfunction, and osteoarthritis if left untreated.  The avascular nature of the cartilage makes regeneration and repair difficult after the damage is done.

The FDA approval is based on the result of Superiority of MACI implant versus Microfracture Treatment in patients with symptomatic articular cartilage defects in the knee (SUMMIT) trial, a Phase 3 two‑year, prospective, multicenter, randomized, open-label, parallel-group study that recruited a total of 144 patients, ages 18 to 54 years, with at least one symptomatic Outerbridge Grade III or IV focal cartilage defect on the medial femoral condyle, lateral femoral condyle, and/or the trochlea. 

The study demonstrated a statistically significantly (p=0.001) greater improvement in KOOS pain and function (SRA) scores in the MACI group compared to the microfracture group at two years.  Patients from the two-year SUMMIT study had the option to enroll in a three-year follow-up study (extension study).  Most the patients who completed the SUMMIT study also participated in the extension study.  Overall efficacy data support a long-term clinical benefit from the use of MACI in patients with cartilage defects of the knee.

David Recker added further “MACI is the first product to show a statistically significantly greater improvement in Knee injury and Osteoarthritis Outcome Score (KOOS) pain and function scores compared to microfracture, a commonly performed alternative surgical treatment for cartilage repair, in a well-controlled Phase 3 clinical study.  With the introduction of MACI, orthopedic surgeons will have a simplified treatment option available for a broader patient population supported by solid clinical evidence.”

The most common side effects reported by patients in the trial are arthralgia, flu like symptoms, joint swelling and back pain. The surgeons need to take many precautions including patient education before MACI is used. The patients also need to comply by registering for a rehabilitation program post operatively.

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[1] https://vcel.com/about-vericel/

[2] http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm533153.htm