PRISMS
Subcutaneous interferon beta-1a
PRISMS demonstrated dose-related clinical and MRI efficacy of subcutaneous interferon beta-1a given three times weekly.
- Phase
- Phase III
- Population
- Relapsing-remitting multiple sclerosis (RRMS)
- Controlled period
- May 1994 — Feb 1997
What was compared
Interferon beta-1a 44 μg
Subcutaneously three times weekly
n=184Placebo
Matching subcutaneous injection three times weekly
n=187Additional randomized arm
Interferon beta-1a 22 μg
Subcutaneously three times weeklyn=189Primary endpoint
Mean relapses per patient
2 years
Primary endpoint results
Mean relapses per participant
Mean relapses
33% and 27% relative reductions for the 44 μg and 22 μg doses.
Selected secondary outcomes
Both doses delayed defined disability progression versus placebo.
Active lesions and accumulated burden of disease were lower with both doses.
Who was studied
Key inclusion criteria
- Adults with RRMS: clinically definite or laboratory-supported definite MS (Poser criteria), present for at least 1 year
- Baseline EDSS 0–5.0
- At least 2 relapses in the previous 2 years
Key exclusion criteria
- Previous systemic interferon, lymphoid irradiation, or cyclophosphamide
- Other immunomodulatory or immunosuppressive treatment in the previous 12 months
Participants at baseline
| Characteristic | IFNβ-1a 44 μgN=184 | IFNβ-1a 22 μgN=189 | PlaceboN=187 |
|---|---|---|---|
| Age, years — median (IQR) | 35.6 (28.4–41.0) | 34.8 (29.3–39.8) | 34.6 (28.8–40.4) |
| Female sex — % | 66% | 67% | 75% |
| MS duration, years — median (IQR) | 6.4 (2.9–10.3) | 5.4 (3.0–11.2) | 4.3 (2.4–8.4) |
| EDSS — mean ± SD | 2.5 ± 1.3 | 2.5 ± 1.2 | 2.4 ± 1.2 |
| Relapses in previous 2 years — mean ± SD | 3.0 ± 1.1 | 3.0 ± 1.1 | 3.0 ± 1.3 |
SD: standard deviation; IQR: interquartile range; EDSS: Expanded Disability Status Scale; IFNβ: interferon beta.
Source: PRISMS Study Group, Lancet 1998, Table 1
Safety signal
- The primary report described both regimens as generally well tolerated.
- Influenza-like symptoms, injection-site reactions, and laboratory abnormalities are central interferon-associated tolerability considerations.
Why it mattered
PRISMS established relapse and MRI efficacy for subcutaneous interferon beta-1a given three times weekly. It provided evidence for two dose regimens, broadening the injectable treatment choices available for RRMS.
Important limitation
The principal efficacy comparison involved two active doses and placebo; the study did not directly compare this regimen with other interferon products.