Abstract
Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematological disorder caused by somatic mutations in the phosphatidylinositol glycan A (PIGA) gene in hematopoietic stem cells, resulting in complement alternative pathway (AP)-mediated severe hemolysis, life-threatening thrombosis, and impaired bone marrow function. The current standard-of-care for PNH consists of anti-C5 blockade with either eculizumab or ravulizumab. While both monoclonal antibodies effectively control intravascular hemolysis (IVH), reduce thrombosis and improve long-term survival, a significant proportion of patients remains anemic and continues to require transfusions, largely due to persistent extravascular hemolysis (EVH). Conversely, pegcetacoplan, a recently FDA-approved anti-C3 inhibitor, prevents both IVH and EVH and showed superiority to eculizumab in improving hemoglobin (Hb) levels in PNH. Nevertheless, the need for effective oral treatment options in PNH remains unmet. Iptacopan (LNP023) is a new, oral, selective and potent first-in-class inhibitor of factor B, a key component of the AP. Recent phase 2 data showed that iptacopan effectively controls both IVH and EVH and leads to rapid, transfusion-free improvements in Hb levels in the majority of PNH patients.
Methods: CLNP023X2204 (NCT03896152) is a multicenter, randomized, open-label phase 2 study in adult PNH patients with active hemolysis and no complement inhibitor treatment within 3 months prior to study entry. Patients are randomized to receive twice daily (BID) iptacopan in one of two dose-sequences, either 25 mg for 4 weeks followed by 100 mg for up to 2 years (Cohort 1) or 50 mg followed by 200 mg (Cohort 2). The key objectives are to assess the effect of iptacopan on markers of IVH/EVH (incl. lactate dehydrogenase (LDH)) and on Hb levels, as well as safety. 12-month interim results are summarized below.
Results: The study has completed enrolment. A total of 13 patients (mean age 38.2 years, 7 female) were randomized to either Cohort 1 (n=7) or 2 (n=6). Mean (SD) lab values at baseline were LDH 2097.8 (911.2) U/L, reticulocytes 203.3 (82.9) x10E9/L, bilirubin 32.4 (10.1) µmol/L, and Hb 85.8 (13.2) g/L, and most patients required red blood cell transfusions in the prior 12 months (median 3.0, range 0-19). At the time of the interim analysis, 11 patients had been treated with iptacopan for at least 52 weeks, with a maximum treatment duration of 81 weeks; 2 patients discontinued treatment early, one after 2 days due to a non-serious adverse event of headache (hence not evaluable for the primary endpoint), the other after 13 weeks due to physician decision. Amongst the 12 evaluable patients, all of whom were anti-C5 naive, all reached the primary endpoint of lowering LDH by at least 60% within the first 12 weeks. The LDH response was rapid and durable, with all patients treated with ≥50 mg BID reaching this threshold after only one week of treatment and all ongoing patients except one maintaining the threshold up until the data cutoff, i.e., for at least 52 weeks. Equivalent improvements were also observed for other markers of IVH and EVH. Similarly, Hb levels improved significantly and durably in most patients, and all except one of the ongoing patients have remained transfusion-free since the start of iptacopan treatment. Moreover, no thromboembolic events occurred during the study, and the FACIT fatigue score improved significantly in most patients. Iptacopan monotherapy was safe, with no severe or serious adverse reported up to the data cutoff.
Conclusion: Iptacopan is a new, well tolerated oral complement AP inhibitor that blocks both IVH and EVH in adult PNH patients with hemolytic PNH. 12-month results from this non-pivotal study demonstrate that iptacopan monotherapy leads to rapid and durable improvements in various hemolytic markers and meaningful and sustained clinical benefit as seen in improvements in Hb levels, transfusion requirement and FACIT fatigue score. These results suggest that proximal inhibition of the complement cascade parallels and further improves the hematological benefit seen with anti-C5 therapies, paving the way for the phase 3 evaluation of iptacopan as potentially new oral first-line therapy for patients with PNH.
Figure 1 Figure 1.
Disclosures
Wong: Astellas Pharma, INc.: Research Funding. Li: Novartis: Current Employment, Current equity holder in publicly-traded company. Rozenberg: Novartis: Current Employment, Current equity holder in publicly-traded company. Nidamarthy: Novartis: Current Employment, Current equity holder in publicly-traded company. Chawla: Novartis: Current Employment, Current equity holder in publicly-traded company. Junge: Novartis: Current Employment, Current equity holder in publicly-traded company.
OffLabel Disclosure:
Iptacopan (LNP023) is a new, oral, selective and potent first-in-class inhibitor of factor B, a key component of the complement alternative pathway. It is currently being investigated in paroxysmal nocturnal hemoglobinuria (PNH) as well as in several renal indications.
Factor B, the complement alternative pathway serine proteinase, is a major constitutive protein synthesized and secreted by resident and elicited mouse macrophages.