Clinical Burden of Paroxysmal Nocturnal Hemoglobinuria Among Patients Receiving C5 Inhibitors in the United States

INTRODUCTION

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, hematologic disease characterized by chronic complement-mediated hemolysis. Treatment with the C5 inhibitor eculizumab has resulted in a reduction in intravascular hemolysis (IVH) and improvements in morbidity and mortality. However, in a single-center cohort of patients with PNH receiving treatment with eculizumab, 72% remained anemic and 36% continued to require transfusions due to ongoing IVH and extravascular hemolysis (McKinley CE, et al.Blood. 2017;130(Suppl 1):3471; Risitano AM, et al.Front Immunol. 2019;10:1157). This study aims to describe the burden of illness in patients with PNH currently being treated with C5 inhibitors (eculizumab and ravulizumab). Overall, the study aims to understand the clinical and hematological outcomes associated with burden of illness in about 150 patients with PNH globally. In these preliminary analyses, the impact of PNH on hematologic and clinical measures is assessed from patients in the United States.

METHODS

A cross-sectional survey was administered to adult patients ≥18 years of age in the United States with a self-reported diagnosis of PNH, recruited through a patient advocacy group. Inclusion criteria to complete the secure online survey included current treatment with either eculizumab or ravulizumab, informed consent, and agreement to adverse event reporting. This study was initiated in July 2020 and is ongoing. Results presented herein are preliminary. Impact of PNH on hematologic and clinical measures will be assessed using the following variables: diagnosis levels; and any patient history of blood transfusions, thrombotic events, renal impairment, fatigue, and other PNH-associated symptoms as well as dosing frequency and treatment patterns. For these preliminary analyses, descriptive statistics will be reported for patients who have completed the survey.

RESULTS

As of August 6, 2020, 58 adult patients with a median age of 52 years (range, 21-88) completed the survey, among which 78% were female. Current medications included eculizumab (n = 20 [34.5%]) or ravulizumab (n = 38 [65.5%]), as well as concurrent anticoagulants (n = 9 [15.5%]) and/or anti-thrombotics (n = 2 [3%]). Most patients initiated treatment with eculizumab (n = 20 [100%]) or with ravulizumab (n = 34 [90%]) ≥3 months before. Median (interquartile range) last known hemoglobin level for patients on eculizumab and ravulizumab was 9.3 g/dL (8.0-11.1) and 10.1 g/dL (8.9-11.5), respectively. Overall, 45 (82%) patients reported hemoglobin values <12 g/dL (eculizumab: 90%; ravulizumab: 78%). Forty (69%) patients reported having ≥1 red blood cell transfusion at any point during their disease. Within the previous 12 months, 53% and 26% of eculizumab- and ravulizumab-treated patients, respectively, had ≥1 transfusion, and 12% and 17% were unsure. Among those patients who had ever received ≥1 transfusion, 6% and 13% had >4 transfusions in the previous 12 months for eculizumab and ravulizumab, respectively. Seventeen patients (29%) reported ≥1 thrombotic event at any point during their disease. Seven patients reported thrombotic events over the previous 12 months; six were receiving ravulizumab. The majority (77%) of patients reported fatigue. Fatigue was reported by nearly 95% of eculizumab-treated patients and 68% of ravulizumab-treated patients.

CONCLUSIONS

Preliminary results from this burden of illness survey demonstrate that a majority of patients with PNH report remaining anemic, despite treatment with C5 inhibitors eculizumab and ravulizumab for a period of ≥3 months.