Repeat steroid injection in knee osteoarthritis possibly beneficial

A steroid injection with TLC599 may offer prolonged pain reduction in osteoarthritis (OA) of the knee and could be an alternative to treatment with corticosteroids. TLC599 was statistically superior to placebo after 12 weeks. A second injection of TLC599 at week 24 provided further benefit for up to 1 year.

In OA, intra-articular injections of corticosteroids can relieve pain, reduce inflammation, and improve mobility. However, the effect is not predictable, and pain relief can have a short duration. The aim of this study was twofold: to confirm the benefit of TLC599 over 6 months and investigate the additional benefit of a repeat injection in eligible participants [1]. The study presenter, Prof. David Hunter (University of Sydney, Australia), explained that TLC599 is a liposomal formulation of dexamethasone sodium phosphate (DSP) administered in 12 mg. Its multi-layer lipid membranes encapsulating DSP allow a controlled slow release at the injection site. Prof. Hunter and colleagues set up a randomised, double-blind phase 3 study in participants with grade 2 or 3 knee OA. Participants had average daily pain (ADP) of 5-9 on a scale of 0-10 and a Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score >6 on a scale of 0-20 in the index knee.

The 506 participants were randomised 2:1:1 to receive an injection of TLC599 12 mg (n=252), DSP 4 mg (n=126), or saline placebo (n=126). Eligible participants received a second blinded TLC599 injection at week 24. The primary endpoint was the change from baseline in WOMAC score at week 12.

Through week 24, TLC599 was numerically superior to placebo for WOMAC pain at all time points, according to Prof. Hunter. The difference was statistically significant at week 12 (95% CI -0.331–[-0.010]; P<0.05). For ADP, TLC599 was statistically superior to placebo at all time points until week 24. At week 12, the ADP reduction for TLC599 was superior to DSP (P<0.05).

In the TLC599, DSP, and placebo group, 203, 89 and 94 participants, respectively, were eligible for a second dose of TLC599 or placebo. With week 24 as the baseline, mean ADP reduction in the TLC599 arm was numerically superior to placebo at all time points through week 52 and statistically superior through week 34. TLC599 was generally well tolerated. The number and type of adverse events were similar among the 3 groups.

1. Spencer-Green G, et al. A phase 3 study of repeat injection of TLC599 in osteoarthritis of the knee: Benefits to 52 weeks. L19, ACR Convergence 2023, 10–15 November, San Diego, USA.

Medical writing support was provided by Michiel Tent.
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Posted on 1 December 202317 May 2024