Cost per Responder Analysis for Pegcetacoplan and Eculizumab in the Treatment of Adults with Paroxysmal Nocturnal Hemoglobinuria

Background: In the absence of clinical guidelines for paroxysmal nocturnal hemoglobinuria (PNH), the European Society for Blood and Marrow Transplantation (EBMT) developed categories for classifying hematological response to complement inhibitor treatment (per Risitano AM, et al. Front Immunol. 2019;10:1157). These categories are: complete (no transfusions, normal stable Hb, and no evidence of hemolysis); major (no transfusions, normal Hb, but evidence of residual intravascular/extravascular hemolysis); good (no transfusions, but persistent chronic mild anemia); partial (persistent chronic moderate anemia and/or occasional red blood cell transfusions); minor (3-6 transfusions every 6 months); no response (>6 transfusions every 6 months). In the phase 3 PEGASUS trial (NCT03500549), 41 and 39 patients previously treated with C5 inhibitors with Hb<10.5 were randomized for treatment with pegcetacoplan or eculizumab, respectively. In a post hoc analysis of the 16-week PEGASUS data, patients were classified by EBMT category to compare hematologic responses of each treatment (per Risitano AM, et al. Blood. 2020; 136(Suppl1):44-5).

Objectives: The objective of this study was to evaluate the number needed to treat (NNT) and treatment costs of pegcetacoplan and eculizumab using EBMT response criteria.

Methods: The analysis used a United States payer perspective and included drug acquisition costs and associated intravenous or subcutaneous administration costs. Drug costs were calculated using dosages for each treatment as given in the PEGASUS trial, including dosage and frequency escalations. Weekly dosages were multiplied by each drug's wholesale acquisition costs from RedBook (2020 United States dollars). We calculated the following outcomes over 16 weeks and by treatment: NNT to achieve each level of response, mean cost per treated patient, total costs, mean cost per treated patient per week, cost per complete responder, cost per good responder, and cost spent on patients with partial/minor/no response.

Additional analyses were conducted to calculate outcomes for treatment-naïve patients treated with pegcetacoplan using similar post hoc analyses of combined 16-week data from the phase 1b-2a PADDOCK/PALOMINO (NCT02588833 and NCT03593200) trials.

Results: Results are summarized in Table 1. Based on response rates, patients with PNH treated with pegcetacoplan had a lower NNT (1.4) to achieve good-to-complete response compared with eculizumab (19.5). NNT to achieve complete response was 2.6 for pegcetacoplan; no patients treated with eculizumab achieved complete response at 16 weeks.

For the PEGASUS trial, mean cost per treated patient was $182,762 (with C5 inhibitor loading dose) and $176,504 over 16 weeks for pegcetacoplan and eculizumab, respectively. Among the 41 pegcetacoplan-treated patients, the total costs were $7,493,256 over 16 weeks. Of 41 pegcetacoplan patients, 16 achieved a complete response, and their total costs were $2.9 million over the 16-week period ($468,328 per complete responder). The total 16-week costs were $2.6 million for 14 patients with good response ($535,233 per good responder). For the 39 eculizumab-treated patients, total 16-week costs were $6,883,637. Two of 39 patients achieved a good response, and their total costs were $353,007 ($3,441,818 per good responder). Of the 39 patients, 37 achieved partial, minor, or no response or discontinued treatment, for a total cost of $6.5 million. This resulted in 95% of total treatment costs being spent on inadequate or no response in the eculizumab arm compared with 27% in the pegcetacoplan arm.

For treatment-naïve patients treated with pegcetacoplan, the mean cost per complete responder ($347,339) and per good responder ($496,198) over 16 weeks were both lower than the cost per responder for patients treated with either pegcetacoplan or eculizumab after previous C5 inhibitor treatment.

Conclusion: Based on the treatment response observed in PEGASUS, the NNT and cost to achieve good or good-to-complete response was lower for pegcetacoplan-treated patients than eculizumab-treated patients, according to EBMT consensus-based hematological response categories. PNH treatment with pegcetacoplan allowed more patients to achieve EBMT defined good-to-complete response and better overall response and is a more efficient use of spending with lower cost per responder in all response categories.

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