Real-World Patient Characteristics, Treatment Patterns and Outcomes for Patients with Atypical Hemolytic Uremic Syndrome Who Have Switched from Eculizumab to Ravulizumab in the USA

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare disease that can cause irreversible organ damage or death. Ravulizumab is a long-acting complement C5 inhibitor approved in the USA, Europe, and Japan for the treatment of aHUS. Ravulizumab was engineered from eculizumab to leverage its clinical benefits and safety profile while reducing dosing frequency. This study assessed real-world patient characteristics, treatment patterns, and clinical outcomes for adult and pediatric patients with aHUS in the USA who switched from eculizumab to ravulizumab.

Methods

This retrospective, non-interventional study evaluated the period from January 1, 2012 to March 22, 2021, using US claims data from the Decision Resources Group Real World Data repository. Eligible patients had ≥ 1 medical claim with an aHUS-related International Classification of Diseases 9/10 diagnosis code and ≥ 1 medical or pharmacy claim for treatment with eculizumab or ravulizumab. Patients with evidence of paroxysmal nocturnal hemoglobinuria, myasthenia gravis, neuromyelitis optical spectrum disorder or Shiga toxin Escherichia coli-related hemolytic uremic syndrome in the 3 months prior to their first aHUS-related treatment were excluded. A patient was classified as 'switched' if they had ≥ 1 claim for eculizumab followed by an initial claim for ravulizumab from 14 to 30 days after the last eculizumab claim. Patients were required to have ≥ 3 months of continuous enrollment in the database prior to their first ravulizumab claim. Ravulizumab treatment was considered to be continuous if all treatment intervals were ≤ 63 days.

Data extracted included: demographics and clinical characteristics at the time of switching to ravulizumab; treatment patterns (including service setting, treatment history before switching to ravulizumab, and subsequent adherence); and clinical outcomes (dialysis, plasma exchange [PE], kidney transplant, and utilization of other end-stage renal disease [ESRD] services) in the 6 months before and after switching to ravulizumab. Data were summarized using descriptive statistics.

Results

Overall, 2101 patients had ≥ 1 eculizumab or ravulizumab claim and an aHUS-related diagnosis. Of these patients, 227 had claims for both eculizumab and ravulizumab with ≥ 3 months of continuous enrollment data before the first ravulizumab claim. The median (lower quartile, upper quartile) treatment interval between the last eculizumab claim and the first ravulizumab claim was 15 (14, 41) days.

In total, 131 patients met the 'switched' criteria. Table 1 presents patient characteristics at the time of switching from eculizumab to ravulizumab. Outpatient facilities were the most common places of service for initiation of switch to ravulizumab (n = 41/89 patients [46%]); private practice facilities were the most common sites for administration of ravulizumab maintenance treatment (n = 84/213 claims [39%]).

Prior to switching to ravulizumab, the median (lower quartile, upper quartile) duration between the first and last eculizumab claim was 788 (252, 1719) days. Among the 95 patients with ≥ 6 months of continuous enrollment after switching to ravulizumab, 73 (77%) patients were treated with ravulizumab continuously for ≥ 6 months. Selected clinical outcomes in the 6 months before and after switching to ravulizumab treatment are presented in Table 2. Although no inferential statistical comparisons were made, data show that fewer switched patients underwent dialysis or utilized other ESRD services in the 6-month post-switch period (with no recorded cases of PE or kidney transplant) compared with the 6-month pre-switch period.

Discussion and conclusions

This study provides real-world data on clinical characteristics and treatment patterns for patients with aHUS who have switched from eculizumab to ravulizumab. The majority of patients switching to ravulizumab were treated continuously for ≥ 6 months according to the treatment schedule in the prescribing information. Ongoing analyses with longer follow-up time will provide inferential assessment of the clinical and economic impacts of switching to ravulizumab.

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