Pharmacotherapeutic group: Antineoplastic and immunomodulating agents, immunostimulants, interferons, ATC code: L03AB13
Peginterferon beta-1a is an interferon beta-1a conjugated with a single, linear molecule of 20,000 Da methoxy poly(ethyleneglycol)-O-2-methylpropionaldehyde (20 kDa mPEG-O-2-methylpropionaldehyde) at a degree of substitution of 1 mole of polymer/mole of protein. The average molecular mass is approximately 44 kDa of which the protein moiety constitutes approximately 23 kDa.
Mechanism of action
A definitive mechanism of action of peginterferon beta-1a in multiple sclerosis (MS) is not known. peginterferon beta-1a binds to the type I interferon receptor on the surface of cells and elicits a cascade of intracellular events leading to the regulation of interferon-responsive gene expression. Biological effects that may be mediated by peginterferon beta-1a include up-regulation of anti-inflammatory cytokines (e.g. IL-4, IL-10, IL-27), down-regulation of pro-inflammatory cytokines (e.g. IL-2, IL-12, IFN-γ, TNF-α) and inhibiting the migration of activated T cells across the blood brain barrier; however additional mechanisms may be involved. Whether the mechanism of action of peginterferon beta-1a in MS is mediated by the same pathway(s) as the biological effects described above is not known because the pathophysiology of MS is only partially understood.
Pharmacodynamic effects
Peginterferon beta-1a is interferon beta-1a conjugated to a single, linear 20 kDa methoxy poly(ethyleneglycol) molecule at the alpha-amino group of the N-terminal amino acid residue.
Interferons are a family of naturally occurring proteins that are induced by cells in response to biological and chemical stimuli, and mediate numerous cellular responses that have been classified as antiviral, antiproliferative, and immunomodulatory in nature. The pharmacological properties of peginterferon beta-1a are consistent with those of interferon beta-1a and are believed to be mediated by the protein portion of the molecule.
Pharmacodynamic responses were evaluated by measuring the induction of interferon-responsive genes including those encoding 2′,5′-oligoadenylate synthetase (2′,5′-OAS), myxovirus resistance protein A (MxA), and several chemokines and cytokines, as well as neopterin (D-erythro-1, 2, 3,-trihydroxypropylpterin), a product of the interferon-inducible enzyme, GTP-cyclohydrolase I. Gene induction in healthy human subjects was greater in terms of peak level and exposure (area under the effect curve) for peginterferon beta-1a compared to non-pegylated interferon beta-1a (IM) when both were given at the same dose by activity (6 MIU). The duration of this response was sustained and prolonged for peginterferon beta-1a, with elevations detected up to 15 days compared to 4 days for non-pegylated interferon beta-1a. Increased concentrations of neopterin were observed in both healthy subjects and multiple sclerosis patients treated with peginterferon beta-1a, with a sustained and prolonged elevation over 10 days compared to 5 days observed for non-pegylated interferon beta-1a. Neopterin concentrations return to baseline after the two week dosing interval.
Clinical efficacy and safety via subcutaneous route
The efficacy and safety of peginterferon beta-1a was assessed from the placebo controlled- first year of a 2 year randomised, double-blind, clinical study in patients with relapsing remitting multiple sclerosis (the ADVANCE study). 1512 patients were randomised to and dosed with 125 micrograms peginterferon beta-1a injected subcutaneously every 2 (n=512) or 4 (n=500) weeks versus placebo (n=500).
The primary endpoint was the annualised relapse rate (ARR) over 1 year. The study design and patient demographics are presented in Table 3
No data are available from clinical efficacy/safety studies directly comparing pegylated with non-pegylated interferon beta-1a in adults, or from patients switching between non-pegylated and pegylated interferon.
Table 3: Study design
| Study design |
| Disease history | Patients with RRMS, with at least 2 relapses within the prior 3 years, and 1 relapse in the prior year, with an EDSS score of ≤5.0 |
| Follow-up | 1 year |
| Study population | 83% treatment-naïve patients 47% ≥2 relapses in prior year 38% at least 1 Gd+ lesion at baseline 92% ≥9 T2 lesions baseline 16% EDSS ≥4 17% previously treated |
| Baseline characteristics |
| Mean age (years) | 37 |
| Mean/Median disease duration (years) | 3.6/2.0 |
| Mean number of relapses within the past 3 years | 2.5 |
| Mean EDSS score at baseline | 2.5 |
RRMS: relapsing remitting multiple sclerosis
EDSS: expanded disability status scale
Gd+: gadolinium-enhancing
Peginterferon beta-1a every 2 weeks significantly reduced the annualized relapse rate (ARR) by 36% compared to placebo (p=0.0007) at one year (Table 4) with consistent reductions of the ARR noted in subgroups defined by demographic and baseline disease characteristics. peginterferon beta-1a also significantly reduced the risk of relapse by 39% (p=0.0003), the risk of sustained disability progression confirmed at 12 weeks by 38% (p=0.0383) and at 24 weeks (post-hoc analysis) by 54% (p=0.0069), the number of new or newly enlarging T2 lesions by 67% (p< 0.0001), the number of Gd-enhancing lesions by 86% (p<0.0001) and the number of new T1 hypointense lesions compared to placebo by 53% (p<0.0001). A treatment effect was observed as early as 6 months, with peginterferon beta-1a 125 micrograms every 2 weeks demonstrating a 61% reduction (p< 0.0001) in new or newly enlarging T2 lesions as compared with placebo. Across relapse and MRI endpoints peginterferon beta-1a 125 micrograms every two weeks showed a numerically greater treatment effect over the peginterferon beta-1a every four weeks dosing regimen at year 1.
Results over 2 years confirmed that efficacy was maintained beyond the placebo controlled first year of the study. Patients exposed to peginterferon beta-1a every 2 weeks showed statistically significant reductions compared to patients exposed to peginterferon beta-1a every 4 weeks over 2 years in a post-hoc analysis for endpoints including ARR (24%, p=0.0209), the risk of relapse (24%, p=0.0212), the risk of disability progression with 24 week confirmation (36%, p=0.0459), and MRI endpoints (new/enlarging T2 60%, Gd+ 71%, and new T1 hypointense lesions 53%; p<0.0001 for all). In the ATTAIN extension study, long-term efficacy with peginterferon beta-1a was maintained with continuous treatment up to 4 years as shown by clinical and MRI measures of MS disease activity. Of a total of 1,468 patients, 658 patients continued at least 4 years of treatment with peginterferon beta-1a.
Results for this study are shown in Table 4.
Table 4: Clinical and MRI results
| | Placebo | Peginterferon beta-1a 125 micrograms every 2 weeks | Peginterferon beta-1a 125 micrograms every 4 weeks |
| Clinical endpoints |
| N | 500 | 512 | 500 |
| Annualised relapse rate | 0.397 | 0.256 | 0.288 |
| Rate ratio 95% CI P-value | | 0.64 0.50 – 0.83 p=0.0007 | 0.72 0.56 – 0.93 p=0.0114 |
| Proportion of subjects relapsed | 0.291 | 0.187 | 0.222 |
| HR 95% CI P-value | | 0.61 0.47 – 0.80 p=0.0003 | 0.74 0.57 – 0.95 p=0.020 |
| Proportion with 12-week confirmed disability progression* | 0.105 | 0.068 | 0.068 |
| HR 95% CI P value | | 0.62 0.40-0.97 p=0.0383 | 0.62 0.40-0.97 p=0.0380 |
| Proportion with 24-week confirmed disability progression* | 0.084 | 0.040 | 0.058 |
| HR 95% CI P-value | | 0.46 (0.26 – 0.81) p=0.0069 | 0.67 (0.41 – 1.10) p=0.1116 |
| MRI endpoints |
| N | 476 | 457 | 462 |
| Mean [Median] no. of new or newly enlarging T2 hyperintense lesions (range) | 13.3 [6.0] (0 – 148) | 4.1 [1.0] (0 – 69) | 9.2 [3.0] (0 – 113) |
| Lesion mean ratio (95% CI) P-value | | 0.33 (0.27, 0.40) p≤0.0001 | 0.72 (0.60, 0.87) p=0.0008 |
| Mean [Median] no. of Gd-enhancing lesions (range) | 1.4^ [0.0] (0 – 39) | 0.2 [0.0] (0 – 13) | 0.9 [0.0] (0 – 41) |
| % reduction vs placebo P-value | | 86 p<0.0001 | 36 p=0.0738 |
| Mean [Median] no. of new T1 hypointense lesions (range) | 3.8 [1.0] (0 – 56) | 1.8 [0.0] (0 – 39) | 3.1 [1.0] (0 – 61) |
| % reduction vs placebo P-value | | 53 p<0.0001 | 18 0.0815 |
HR: hazard ratio
CI: confidence interval
* Sustained disability progression was defined as at least a 1 point increase from baseline EDSS ≥ 1 or 1.5 point increase for patients with baseline EDSS of 0, sustained for 12/24 weeks. ^n=477
Patients who failed previous MS treatment were not included in the study.
Subgroups of patients with higher disease activity were defined by relapse and MRI criteria as reported below, with the following efficacy results:
- For patients with ≥1 relapse in the previous year and ≥9 T2 lesions or ≥1 Gd+ lesion (n=1,401), the annual relapse rate at 1 year was 0.39 for placebo, 0.29 for peginterferon beta-1a every 4 weeks and 0.25 for peginterferon beta-1a every 2 weeks. Results in this subgroup were consistent with those in the overall population.
- For patients with ≥2 relapses in the previous year and at least 1 Gd+ lesion (n=273), the annual relapse rate at 1 year was 0.47 for placebo, 0.35 for peginterferon beta-1a every 4 weeks, and 0.33 for peginterferon beta-1a every 2 weeks. Results in this subgroup were numerically consistent with those in the overall population but not statistically significant.
IM and SC bioequivalence study
An -open-label, crossover study enrolled 136 subjects to assess the bioequivalence of single doses of 125 micrograms of Plegridy administered SC and IM injection in healthy volunteers.
The serum concentration of neopterin, a marker of interferon beta activity, following administration of 125 micrograms peginterferon beta-1a IM and SC was measured for pharmacodynamic (PD) analysis.
The serum neopterin concentration versus time profiles following single doses of 125 micrograms peginterferon beta-1a SC or 125 micrograms peginterferon beta-1a IM were similar, with maximal concentrations (Epeak) reached at a median ETmax of 40.1 hours and 44.0 hours, respectively. Geometric mean neopterin levels increased from baseline to maximum concentration similarly between the 2 injection routes, with the increase from 8.0 to 22.6 nmol/L for SC, and from 8.1 to 23.2 nmol/L for IM. The overall systemic exposure to neopterin (EAUC0 336h and EAUC0-504h) were also similar between the 2 routes of administration.
Since bioequivalence was demonstrated between the IM and SC routes of administration, it is expected that IM and SC peginterferon beta-1a will have a similar efficacy profile.
Paediatric population
The safety and effectiveness of peginterferon beta‑1a in paediatric RRMS was evaluated in a randomised, open-label active-controlled (interferon beta-1a) parallel group study in patients with RRMS aged 10 to less than 18 years of age.
152 patients were randomized in a 1:1 ratio to treatment with peginterferon beta‑1a, administered at a dose of 125 μg SC every 2 weeks or interferon beta-1a administered at a dose of 30 μg IM injection once weekly, for 48 weeks. 124 patients (peginterferon beta‑1a n=66; interferon beta-1a n=58) completed 48 weeks of the study.
The primary endpoint, the adjusted annualized relapse rate (ARR) at week 48 was numerically lower in patients treated with peginterferon beta‑1a (0.386) compared to patients who received interferon beta-1a (0.521).
The main secondary endpoint at week 48, was the number of participants free of new or newly enlarging T2 hyperintense lesions on brain MRI scans. At week 48, 0.136 (95% CI: 0.064, 0.243) participants in peginterferon beta‑1a group were free of new or newly enlarging T2 hyperintense lesions compared to participants in interferon beta-1a group 0.065 (95% CI: 0.018, 0.157).