A new subgroup analysis of the phase 3 ADHERE trial (NCT04281472) reveals that weekly 1000-mg subcutaneous (SC) efgartigimod PH20 (Vyvgart Hytrulo; Argenx) is efficacious across a range of patients with chronic inflammatory demyelinating polyneuropathy (CIDP), regardless of prior CIDP therapy.
The findings, presented at the 2024 American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) meeting, indicate that the majority of participants showed confirmed evidence of clinical improvement (ECI) with efgartigimod PH20 SC, irrespective of their prior treatment. Specifically, 77.8% (95% CI, 65.5–87.3) of those previously on corticosteroids, 58.8% (95% CI, 50.9–66.4) of those on intravenous immunoglobulin (IVIg)/SCIg, and 72.3% (95% CI, 62.2–81.1) of those off treatment demonstrated ECI.
Luc Truyen, MD, PhD, chief medical officer at Argenx, stated, “Vyvgart continues to deliver impactful benefits to patients in terms of safety, speed of onset, depth of response, and durability of response.” He further highlighted the potential of Argenx's neurology pipeline, including empasiprubart and ARGX-119, to advance transformative outcomes for more patients.
ADHERE Trial Design and Results
The ADHERE trial was a phase 3, multistage, double-blind, placebo-controlled study assessing the efficacy and safety of SC efgartigimod PH20 in CIDP patients. Efficacy was evaluated during an open-label treatment period of up to 12 weeks (stage A) and a randomized-withdrawal, double-blind, placebo-controlled period of up to 48 weeks (stage B). Subgroups were defined based on prior CIDP therapy at screening and various patient/disease characteristics.
The analysis included patients previously treated with corticosteroids, IVIg/SCIg, or those who were treatment-naïve (off-treatment) for at least 6 months before study entry. Endpoints included confirmed ECI, time to ECI (stage A), time to first adjusted Inflammatory Neuropathy Cause and Treatment deterioration (relapse, defined as at least a 1-point score increase, stage B), and safety (stages A/B).
Key Findings on Efficacy and Safety
Analysis of different patient/disease characteristics by subgroups revealed generally similar rates of ECI (stage A) and hazard ratios for a decrease in the risk of relapse (stage B). Efgartigimod PH20 SC was well-tolerated, with most treatment-emergent adverse events reported as mild to moderate in severity.
Regulatory Approval and Clinical Impact
In June 2024, the FDA approved Argenx's SC efgartigimod PH20 for treating adults with CIDP, marking it as the first and only neonatal Fc receptor blocker approved for this condition. This approval was based on data from the pivotal phase 3 ADHERE study, where treatment with efgartigimod PH20 significantly reduced relapse risk compared to placebo (61% attenuated risk, P = .00039). The safety profile was consistent with prior studies.
