Efgartigimod successful in immune thrombocytopenia 

Efgartigimod, a human IgG1 Fc-fragment that prevents the recycling of IgG but not albumin, significantly improved platelet counts in patients with primary immune thrombocytopenia (ITP), compared with placebo. Moreover, the phase 3 ADVANCE IV study showed that the study drug was well tolerated by the study participants.

“The effectiveness of the current treatment options for patients with ITP is limited, and better therapies are needed to improve their quality-of-life,” said Prof. Catherine Broome (Georgetown University, Washington DC, USA). The ADVANCE trial (NCT04188379) randomised 131 patients with chronic or persistent ITP who had received at least 2 prior ITP treatments, or 1 prior and 1 concurrent treatment, and had platelet counts <30×10⁹/L 2:1 to efgartigimod 10 mg/kg once weekly, intravenously administered, or placebo [1]. The dosing of efgartigimod was adjusted according to platelet counts that were performed during the treatment period. The primary endpoint was the proportion of patients with a sustained platelet count response, defined as ≥50×10⁹ platelets/L in ≥4 out of 6 visits in weeks 19–24 of the study, in the absence of intercurrent events.

In total, 21.8% of the participants in the efgartigimod arm and 5.0% of the participants in the placebo arm achieved the primary endpoint, reflecting a significant difference between the arms in favour of the experimental drug (P=0.0316). In addition, the number of cumulative weeks of disease control showed a benefit for the efgartigimod arm over the placebo arm (mean 6.1 vs 1.5; P=0.0009; see Figure). Prof. Broome added that the results were consistent across subgroups.

Figure: Efgartigimod-treated participants experienced substantially more weeks with disease control [1]

Efgartigimod was well tolerated in this study population and results were consistent with previous data that has been published on the drug [2,3]. Serious adverse events (AEs) were more prevalent in the placebo arm than in the efgartigimod arm (15.6% vs 8.1%). Prof. Broome commented that this was mostly due to an increased rate of bleeding events in the placebo arm (86.7% vs 70.9%). Finally, the infection rate was numerically slightly higher in the efgartigimod arm than in the placebo arm (29.1% vs 22.2%).

To summarise, efgartigimod was efficacious and well tolerated in patients with chronic or persistent ITP. The study results suggest that treatment adjustments can be made based on platelet counts.

1. Broome CM, et al. Efficacy and Safety of Intravenous Efgartigimod in Adults with Primary Immune Thrombocytopenia: Results of a Phase 3, Multicenter, Double-Blinded, Placebo-Controlled, Randomized Clinical Trial (ADVANCE IV). Abstract 3, ASH 64^th Annual Meeting, 10–13 December 2022, New Orleans, LA, USA.
2. Howard JF jr, et al. 2019;92(23):e2661–e2673.
3. Howard JF jr, et al. Lancet Neurol. 2021;20(7):526–536.

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Posted on 20 February, 2023