Pharmacotherapeutic group: Immunosuppressants, Complement inhibitors, ATC code: L04AJ09
Mechanism of action
Danicopan binds reversibly to complement factor D (FD) and acts as a selective inhibitor of FD function. By inhibiting FD, danicopan selectively blocks the activation of complement alternative pathway (AP), leading to prevention of the production of multiple effectors, that include C3 fragments, after AP activation. The 2 other complement pathways (classical and lectin) remain active. Danicopan's inhibitory effect on AP activation inhibits the deposition of C3 fragments on PNH red blood cells; such deposition is a key cause of the EVH which can become clinically significant in a small subset of patients with PNH on a C5 inhibitor. Maintenance of C5 inhibition controls the life-threatening pathophysiological consequences of terminal complement activation underlying PNH.
Pharmacodynamic effects
In a clinical trial in patients with PNH with clinically significant EVH treated with ravulizumab or eculizumab, danicopan demonstrated the expected inhibition of AP activity, reduction of plasma Bb (a cleaved product of complement factor B by FD) level, as well as decreased C3 fragment deposition on circulating PNH red blood cells.
Cardiac electrophysiology
Single oral doses of danicopan administered at 400 mg, 800 mg, or 1 200 mg did not prolong QTc interval. There were no categorical alerts of concern regarding electrocardiogram intervals or wave form abnormalities.
Clinical efficacy and safety
The efficacy and safety of danicopan in adult patients with PNH who have clinically significant EVH were assessed in a multiple-region, randomised, double-blind, placebo-controlled, phase 3 study (ALXN2040-PNH-301). The study enrolled 86 patients with PNH who had been treated with a stable dose of ravulizumab or eculizumab for at least the previous 6 months and had anaemia (haemoglobin [Hgb] ≤ 9.5 g/dL [5.9 mmol/L]) with absolute reticulocyte count ≥ 120 × 109/L, with or without transfusion support.
Danicopan was administered in accordance with the recommended dosing described in section 4.2 (150 mg three times a day, and up to a maximum of 200 mg three times a day depending on the clinical response).
Patients were evaluated for history of vaccination and had to be vaccinated against meningococcal infection prior to or at the time of initiating treatment with danicopan if vaccination status within 3 years could not verified.
Patients were randomised to danicopan or placebo three times a day in a 2:1 ratio for 12 weeks in addition to background ravulizumab or eculizumab treatment in both groups. After week 12, all patients received danicopan as an add-on to their background ravulizumab or eculizumab treatment up to week 24. At the end of the treatment periods (week 24), patients were offered to enter a long‑term extension (LTE) period and continued to receive danicopan with background ravulizumab or eculizumab.
Demographic or baseline characteristics were generally balanced between treatment groups. PNH medical history was similar between the treatment group and the placebo control group. The mean age at baseline was 52.8 years and the majority of patients were female (62.8%). Mean haemoglobin levels at baseline were 7.75 g/dL [4.81 mmol/L] and mean reticulocyte counts were 239.40 × 109/L. Within 24 weeks prior to the first dose, 76 patients (88.4%) had pRBC/whole blood transfusions and the mean number of transfusion instances was 2.6. Mean LDH levels were 298.13 U/L and mean FACIT‑Fatigue scores were 33.24. The study enrolled 51 patients (59.3%) on ravulizumab and 35 patients (40.7%) on eculizumab.
The primary endpoint was the change in Hgb level from baseline to week 12. Secondary endpoints were the proportion of patients with Hgb increase of ≥ 2 g/dL [1.2 mmol/L] at week 12 in the absence of transfusions, the proportion of patients with transfusion avoidance through week 12, the change from baseline in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scores at week 12, and change from baseline in absolute reticulocyte count at week 12. Transfusion avoidance was considered as achieved only by the patients who did not receive a transfusion and did not meet the protocol specified guidelines for transfusion from baseline through 12‑week treatment period 1.
The primary evidence for efficacy analysis is based on a pre-specified analysis performed when the first 63 randomised participants reached the end (either completed or discontinued) of the 12-week treatment period 1. Danicopan as an add-on to ravulizumab or eculizumab was superior to placebo as an add-on to ravulizumab or eculizumab for the primary endpoint and resulted in a statistically significant increase in Hgb from baseline to week 12. The LS mean change in Hgb from baseline was 2.94 g/dL [1.82 mmol/L] in the danicopan group compared with 0.50 g/dL [0.31 mmol/L] in the placebo group. The treatment group difference was 2.44 g/dL [1.51 mmol/L] (95% CI: 1.69 [1.05], 3.20 [1.99]); p < 0.0001). Danicopan also achieved statistically significant improvement compared to placebo for all 4 secondary endpoints: proportion of patients with Hgb increase of ≥ 2 g/dL [1.2 mmol/L] in the absence of transfusion (59.5% vs. 0%, treatment difference: 46.9 [95% CI: 29.2, 64.7]; p < 0.0001), proportion of patients with transfusion avoidance (83.3% vs. 38.1%, treatment difference: 41.7 [95% CI: 22.7, 60.8]; p = 0.0004), change in FACIT‑Fatigue score (7.97 vs. 1.85, treatment difference: 6.12 [95% CI: 2.33, 9.91]; p = 0.0021) and change in absolute reticulocyte count (-83.8 vs. 3.5, treatment difference: -87.2 [95% CI: ‑117.7, ‑56.7]; p < 0.0001).
Supplemental results at week 12 based on all randomised patients (N = 86) are consistent with those from the primary efficacy analysis (N = 63). Danicopan as an add-on to ravulizumab or eculizumab was superior to placebo as an add-on to ravulizumab or eculizumab for the primary endpoint and resulted in a statistically significant increase in Hgb from baseline to week 12 (see Table 2 and Figure 1). Danicopan also achieved statistically significant improvement compared to placebo for all 4 secondary endpoints (see Table 2).
During the 12-week treatment period 1, 14 of 57 (24.6%) patients in the danicopan add-on group were dose escalated from 150 mg to 200 mg three times a day. Four patients (2 randomised to danicopan and 2 randomised to placebo) discontinued treatment during treatment period 1. There were no discontinuations due to haemolysis.
Table 2: Analysis of primary and secondary endpoints at week 12 (all randomised patients)
| | Danicopan (add-on with ravulizumab or eculizumab) N = 57 | Placebo (add-on with ravulizumab or eculizumab) N = 29 |
| Change in haemoglobin level (primary endpoint) |
| Mean change from baseline to week 12 (g/dL [mmol/L]) | 2.81 [1.74] | 0.46 [0.29] |
| Treatment difference* (95% CI) | 2.35 [1.46] (1.63 [1.01], 3.06 [1.90]) |
| Proportion of patients with haemoglobin increase of ≥ 2 g/dL [1.2 mmol/L] in the absence of transfusion |
| At week 12 (%) | 54.4 | 0 |
| Treatment difference** (95% CI) | 47.5 (32.6, 62.4) |
| Proportion of patients with transfusion avoidance |
| Through 12-week treatment period (%) | 78.9 | 27.6 |
| Treatment difference** (95% CI) | 48.4 (31.8, 64.9) |
| Change in FACIT‑Fatigue score |
| Mean change from baseline to week 12 | 8.10 | 2.38 |
| Treatment difference* (95% CI) | 5.72 (2.62, 8.83) |
| Change in absolute reticulocyte count |
| Mean change from baseline to week 12 (109/L) | -92.5 | -0.8 |
| Treatment difference* (95% CI) | -91.7 (-120.1, -63.4) |
* Based on mixed-effect model for repeated measures.
** Difference in rates and associated 95% CI are calculated using Miettinen and Nurminen method adjusting for stratification factors.
Abbreviations: CI = confidence interval; FACIT = Functional Assessment of Chronic Illness Therapy
Figure 1: Mean change in haemoglobin level from baseline to week 12 (all randomised patients)
Results at week 24 were consistent with those at week 12 and support maintenance of the effect. Among the 55 patients with PNH who received danicopan for 24 weeks, the LS mean change in Hgb from baseline to week 24 was 2.95 g/dL [1.83 mmol/L] (95% CI: 2.42 [1.50], 3.48 [2.16]), 69.1% maintained transfusion avoidance through week 24 and 41.8% had a Hgb increase of ≥ 2 g/dL [1.2 mmol/L] in the absence of transfusion at week 24. These patients also had consistent improvement in FACIT‑Fatigue scores that was maintained through 24 weeks, the mean change from baseline was 6.19 (95% CI: 4.10, 8.29).
A total of 80 patients entered the LTE, during which all patients received danicopan. Efficacy results up to Week 72 are consistent with those at Week 12 and Week 24. In patients who received danicopan for 72 weeks (N = 38), the mean change in Hgb from baseline to Week 72 was 2.81 g/dL [1.74 mmol/L].
Paediatric population
The European Medicines Agency has deferred the obligation to submit the results of studies with Voydeya in one or more subsets of the paediatric population in the treatment of PNH (see section 4.2 for information on paediatric use).