Interferon-beta Versus Glatiramer Acetate as Initial Treatment for Multiple Sclerosis: Long-term Follow-up

Background

Since 1993, 15 disease-modifying therapies have been approved by the FDA for the treatment of relapsing-remitting multiple sclerosis (MS). First-generation injectable disease-modifying therapies include interferon-beta (IFN-beta) products and glatiramer acetate. Although more recently approved disease-modifying therapies offer better efficacy, IFN-beta products and glatiramer acetate continue to be used due to their known and favorable safety profiles.

Most clinical trials of drugs for the treatment of MS were designed to evaluate outcomes, specifically relapse rates, in relatively short intervals of up to 2 years. Two types of long-term data for IFN-beta products and glatiramer acetate are available: 1) data comparing IFN-beta—treated patients with untreated patients, and 2) data from long-term follow-up studies from early phase 3 clinical trials. Additional long-term studies are needed to better understand the effects of IFN-beta products and glatiramer acetate on disability progression. Likewise, additional long-term data are needed to better predict which patients will respond to IFN-beta products versus glatiramer acetate.

Methods

This retrospective study assessed the long-term efficacy of first-generation injectable disease-modifying products (ie, INF-beta products and glatiramer acetate) to identify patients who had a better disease course with INF-beta products or glatiramer acetate. Patients enrolled in the Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women’s Hospital and the Partners MS Center (CLIMB) trial who had either clinically isolated syndrome or relapsing MS were eligible for inclusion in the analysis. Additionally, patients were required to have initiated treatment with 1 of the 3 primary forms of INF-beta (INF-beta-1a subcutaneous, INF-beta-1a intramuscular, or INF-beta-1b) or glatiramer acetate prior to 2008 and within 5 years of disease onset. Patients could not have been treated with any other disease-modifying treatments and were required to have Expanded Disability Status Scale (EDSS) scores of 3.5 or less prior to or within 90 days of treatment initiation. The primary outcome measures were time to an EDSS score of 4, time to an EDSS score of 6, and the EDSS score 7 years after treatment initiation.¹

Results

Baseline Characteristics

A total of 294 patients were included in the analysis, including 144 patients who received INF-beta and 150 patients who received glatiramer acetate. Baseline demographics (ie, gender, age at treatment initiation, disease duration at treatment initiation, EDSS score at treatment initiation, and number of attacks in the year prior to treatment initiation) were similar between INF-beta and glatiramer acetate treatment groups.¹

Time to Treatment Cessation

Glatiramer acetate and INF-beta products provided a long-term treatment option for some patients, as a subset of patients continued with treatment for more than 10 years. Patients who received glatiramer acetate remained on treatment significantly longer than those who were treated with INF-beta products (4.7 years vs 2.6 years; P = .002).

EDSS

The time to an EDSS score of 4 or 6 did not significantly differ between groups. After 7 years of treatment, the estimated proportion of patients reaching an EDSS score of 4 was 0.11 for both groups. Likewise, the estimated proportion of patients reaching an EDSS score of 6 was 0.08 for both groups. Seven years after treatment initiation, there were only minor differences in EDSS scores between groups.¹

Treatment and Disease Course

Although the results were not significant, older patients treated with INF-beta had a somewhat better disease course compared with those who received glatiramer acetate.¹

Conclusion

The results of this analysis suggest that long-term outcomes with IFN-beta products and glatiramer acetate are generally similar. Patients who received glatiramer acetate were likely to stay on treatment longer; however, patients in both treatment groups experienced limited disease progression, and only minor differences were observed between the treatment groups for the other study outcomes.

Reference

1. Healy BC, Glanz BI, Zurawski JD, Mazzola M, Chitnis T, Weiner HL. Long-term follow-up for multiple sclerosis patients initially treated with interferon-beta and glatiramer acetate. J Neurol Sci. 2018;394:127-131. doi: 10.1016/j.jns.2018.09.020.