Efficacy and safety of CARTIGROW® in patients with articular cartilage defects of the knee joint: a four year prospective studys

This prospective, open-label, phase III study was conducted from April 2015 to September 2019 at four centres across India (Deenanath Mangeshkar Hospital & Research Centre, Pune; Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi; Krishna Institute of Medical Sciences, Secunderabad; Kasturba Medical College & Hospital, Manipal). Patients (19 to 38 years) with focal articular cartilage defects of the knee joint with grade III and IV severity per the International Cartilage Repair Society were enroled. Patients with intact meniscus, stable knee with normal alignment, and normal joint space with no inflammation or arthritic changes in the joint were eligible for the study. In patients with mal-aligned knee(s), corrective procedures were carried out either prior to or with biopsy. Patients with BMI > 35 kg/m² and/or those with lesions of sizes < 1 cm² or > 12 cm² were excluded. Other key exclusion criteria included degenerative joint changes such as osteoarthritis, avascular necrosis and articular cartilage defects like kissing lesions, mal-aligned articulating joints, unstable articulating joint ligament and/or bone defects around the defective cartilage, and patients with inflammatory or rheumatoid arthritis. Patients whose cartilage cells did not grow sufficiently in vitro were also excluded from the study.

This study was conducted in accordance with the ethical principles that have their origin in the current Declaration of Helsinki (2013) and was consistent with The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, Good Clinical Practice (GCP), Indian GCP guidelines issued by Central Drug Standard Control Organization, local regulations and ethical guidelines for biomedical research on human participants issued by Indian Council of Medical Research. The Drug Controller General of India, Central Drug Standard Control Organization under Ministry of Health & Family Welfare, Government of India approved this phase III clinical study. Patients were enroled only after obtaining approval from Ethics Committees of all four centres. The study was registered in the Clinical Trial Registry of India (CTRI/2015/04/005661). All patients and/or their legally acceptable representatives provided informed consent before participation.

This study involved seven visits, each for screening, biopsy, pre-implantation, implantation, and three follow-up visits at 1.5 weeks, three months and six months (Fig. 1). The follow-up visit at 4 years was not mandatory (voluntary visit), and hence, the patient data of those reporting to clinic for routine care were collected. After initial patient screening, CARTIGROW® procedure was conducted in two stages. In the first stage, arthroscopy was performed to evaluate the osteochondral defect. Loose bodies secondary to trauma or osteochondritis dissecans were removed during the procedure. A full-thickness articular cartilage punch biopsy was performed to harvest hexagonal osteochondral cylinders (approximately 6–8 mm in size) with the subchondral bone. All unstable and damaged cartilage was removed with utmost care to avoid penetration into the subchondral bone. Cartilage specimen(s) were then sent to a GMP-certified cell culture laboratory (Regrow Biosciences Pvt. Ltd.) in a sterile container with culture medium. Harvested cells from the biopsy were then processed for three to four weeks in the laboratory to achieve a uniform suspension (CARTIGROW®). If cells could not be grown or cultured within seven days for any patient, they were considered a “screen failure.” The final product was packaged in cold chain (2–8°C) and transported to the hospital for implantation. In the second stage, arthrotomy was performed and CARTIGROW® was implanted directly onto the defect while maintaining a gravity eliminating position parallel to the floor to ensure that the implant did not overflow into the surrounding areas. Stability of the implant was assessed by moving the knee from full extension to flexion for ten cycles. Skin and muscle defects were closed in layers and a compression dressing was applied.

Patients followed a post-operative rehabilitation program that included non-weight bearing exercises with walker immediately post-ACI to four weeks after ACI gradually followed by partial weight-bearing exercises at five to eight weeks. Using continuous passive motion (CPM) machine, 140° of motion range was achieved at eight weeks after ACI. Patients were also allowed early mobilisation for ranges 0–90° with CPM machine. Muscle strengthening exercise: four point exercise, isometric exercise, hamstring exercise, and squatting exercise were advised; and 12 weeks after ACI, patients could perform stationary bike activities without resistance. Patients would start walking lightly at 13 weeks and jogging at six months followed by high-intensity exercises and sports activities, nine months after ACI. Subjects were advised to avoid any non-drug therapies like massage, acupuncture, acupressure, or any other method of joint manipulation for the affected joint during the study period. Deviations from the rehabilitation program were at the investigator’s discretion based on patient’s condition.

Efficacy endpoints were change in the International Knee Documentation Committee (IKDC) knee examination score and the VAS score from baseline to six months and four years. The other endpoints of improvement in magnetic resonance imaging (MRI) from baseline to six months and four years were subjectively/qualitatively assessed by an independent radiologist. The IKDC score is a patient-completed questionnaire with responses categorised on ordinal scale. Total possible score ranges from 0 to 100 where 100 represents no limitation with daily or sporting activities and absence of symptoms [12]. Pain VAS provides one-dimensional measure of pain intensity on a vertical or horizontal continuous scale 10 cm in length, anchored by two verbal descriptors, one for each symptom extreme. A higher score indicates greater pain intensity. MRI examinations were performed at not less than 1.5-T and evaluated qualitatively to assess the regeneration of articular cartilage at the defect site. Morphological scoring was done with a modified magnetic resonance observation of the cartilage repair tissue.

The magnetic resonance observation of cartilage repair tissue (MOCART) score was done by single, independent, experienced musculoskeletal radiologist at four years who was blinded to the clinical details and clinical outcome assessment [13]. Safety assessments (physical examination, vital signs and laboratory assessments) were performed at biopsy visit until the follow-up visit at six months.

A total of 13 patients were required to test the hypothesis with 80% power at p = 0.05 based on the mean reduction of VAS score of 27.19, and standard deviation of 31.33 reported in previous literature [14]. After considering a 10% drop-out rate, our sample size was 14 patients.

No adverse events or serious adverse events were reported at the end of six months and during the voluntary follow-up at four years.

The IKDC score improved from baseline (32.84 ± 9.25) to 67.49 ± 13.03 at six months (67.49 ± 13.03) (p < 0.001) but reduced at four year follow-up (60.18 ± 10.33), but was still statistically significant compared to baseline (p = 0.0001) (Table 2).

Mean VAS score reduced significantly at 24 weeks vs baseline (72.00 ± 14.40 vs 16.64 ± 17.03, mean reduction: − 55.36 ± 24.49, p < 0.0001) that further reduced at four years (12.72 ± 8.62) suggesting statistically significant reduction in pain symptoms (p = 0.0001) (Table 2).

Definite improvement from baseline MRI was noted in the follow-up MRI conducted at four years for seven patients. The MOCART was performed at four years to evaluate cartilage regeneration. The defect was filled completely with regenerated articular cartilage in 4/7 (57%) patients compared to baseline. Optimal cartilage interface was seen in 5/7 (71%) patients with 4/7 (57%) them showing intact cartilaginous integrity (Table 3). Additionally, regenerated cartilage showed continuity with the surrounding articular cartilage with no fissure, cleft formation or any other irregularities and no signs of infections in surrounding tissues with mean MOCART score of 60.71 ± 26.65 (Fig. 3). Figure 4 shows pre-operative, intra-operative and post-operative arthroscopy images showing the defect before and repair of defect after the treatment. Overall, no patients required any surgeries for treating cartilage repair, or hyaluronic acid/steroids at six months (n = 14) or four years post-treatment (n = 7).