Treatment for a year with the human anti–nerve growth factor monoclonal antibody fulranumab provided pain relief and functional benefits to patients with moderate to severe chronic osteoarthritis knee or hip pain but continued to show signs that the biologic may contribute to rapid progression of disease in a proportion of patients who came to need joint replacement, especially when used concurrently with nonsteroidal anti-inflammatory drugs.
The findings come from the double-blind extension phase of a 12-week, phase II, placebo-controlled, double-blind, randomized study that found significant reduction in the average pain intensity score (P less than or equal to .030) for patients who took fulranumab (Pain. 2013 Oct;154:1910-9). The investigators wanted to determine the long-term safety of the biologic in light of the Food and Drug Administration’s 2010 “clinical hold” on studies of anti–nerve growth factor (anti-NGF) drugs such as fulranumab after concerns emerged that the class of anti-NGF antibodies may be associated with potential treatment-emergent adverse events (TEAEs) leading to joint destruction.
The long-term safety and efficacy results in the extension phase of the study when fulranumab was given as an adjunctive therapy to standard pain therapy revealed higher rates of serious TEAEs, including joint replacement, that were associated with fulranumab. While most of those TEAEs were independently adjudicated to stem from normal progression of OA, one-fifth of the patients on fulranumab who needed joint replacement had rapid progression of OA (RPOA).
Investigators led by Panna Sanga, MD, director of clinical research at Janssen, sought to determine the effects of the anti-NGF biologic as an adjunctive therapy to standard pain therapy over a 92-week period in 401 patients who had completed the 12-week efficacy study, as well as over a 26-week posttreatment follow-up. In the current extension phase of the trial, patients continued on their randomized dose in the original trial of placebo or subcutaneous fulranumab 1 mg or 3 mg every 4 weeks or fulranumab 3 mg, 6 mg, or 10 mg every 8 weeks, but they were permitted to change their concurrent pain medications as clinically needed.
Although the study intended for patients to receive 2 years of treatment (104 weeks), the FDA’s clinical hold meant that the median duration of exposure to fulranumab in the extension study was only 365-393 days across the dosing regimens, the authors explained (Arthritis Rheumatol. 2016 Oct 16 doi: 10.1002/art.39943).
Overall, 421 (90%) of 466 intent-to-treat patients experienced at least one TEAE during both study phases, with similar incidence between those randomized to placebo (n = 69, 88%) and the fulranumab groups (n = 352, 91%).
TEAEs that occurred with a frequency of 10% or more among all fulranumab-treated patients were arthralgia (21%), OA (18%), paresthesia, and upper respiratory tract infection (13% each), while these were arthralgia (15%), OA (14%), and sinusitis (12%) among patients randomized to placebo.
A total of 109 patients (23%) reported serious TEAEs, including 13 (17%) taking placebo and 96 (25%) taking fulranumab. Serious TEAEs that were reported in 5% or more of patients in the fulranumab groups were knee arthroplasty (n = 38, 10%) and hip arthroplasty (n = 26, 7%). Overall, 81 joint replacements occurred in 71 patients (placebo: n = , 11%; fulranumab: n = 63, 89%).
An independent adjudication committee that the study sponsor, Janssen, established after the study was put on hold ruled that the majority of these joint replacements resulted from the normal progression of OA (n = 56, 79%). However, the adjudication committee determined that 15 (21%) patients in the fulranumab treatment groups had RPOA.
The study authors pointed out that the patients with RPOA regularly used NSAIDs and had a prior history of OA in the affected joint. Nevertheless, because of the small number of RPOA cases per treatment group, a drug or dose effect for RPOA could not be evaluated, they said.
“Future studies are warranted to demonstrate whether limiting the use of concomitant chronic NSAIDs and using only lower doses of fulranumab may reduce the risk of RPOA,” they wrote.
The extension study also looked at the longer-term efficacy of fulranumab. Efficacy endpoints on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function subscales and the Patient Global Assessment (PGA) scores that looked at changes from baseline showed that in comparison with placebo, dosing regimens of fulranumab 3 mg every 4 weeks and 10 mg every 8 weeks gave “continued effective relief of the pain associated with knee and hip OA as early as week 4 and was maintained up to week 53,” the researchers reported.
These results were further corroborated by improvements in physical function on the WOMAC physical function subscale and PGA scale scores, which suggested “sustained efficacy of long-term fulranumab treatment,” they said.
All authors except one were employees of Janssen.