MSCRG

Intramuscular interferon beta-1a

MSCRG tested whether once-weekly intramuscular interferon beta-1a could delay sustained disability progression in relapsing multiple sclerosis.

Phase: Phase III
Population: Relapsing multiple sclerosis (RMS)
Controlled period: Nov 1990 — 1993

What was compared

RandomizedDouble-blindPlacebo-controlledMulticenter

Intervention

Interferon beta-1a

30 μg intramuscularly once weekly

n=158

Comparator

Placebo

Matching intramuscular injection once weekly

n=143

301 randomizedUp to 104 weeks controlled phase

Primary endpoint

Prespecified outcome

Sustained disability progression

Kaplan–Meier estimate at 104 weeks

Outcome figure

Primary endpoint results

Intervention Comparator or reference

Sustained disability progression

Participants with progression (%)

Kaplan–Meier estimate at 104 weeks

Interferon beta-1a

21.9%

Placebo

34.9%

Time to sustained EDSS progression was significantly delayed (P=0.02).

Selected secondary outcomes

Relapses among 2-year completers

Annual relapse rate was 0.61 with interferon beta-1a and 0.90 with placebo.

MRI activity

Gadolinium-enhancing lesion activity favored interferon beta-1a.

Study population

Randomized: 301 randomized
Age: 18–55 years eligible
Disability: EDSS 1.0–3.5
Disease definition: Relapsing multiple sclerosis

Who entered the trial

Key inclusion criteria

Definite relapsing multiple sclerosis
At least two exacerbations in the preceding 3 years
Mild-to-moderate baseline disability

Key exclusion criteria

Chronic progressive disease without relapses
Recent immunosuppressive or interferon therapy
Other illness that could compromise neurologic assessment

Safety signal

Influenza-like symptoms, headache, muscle ache, and injection-related effects were associated with interferon treatment.
Laboratory monitoring was required for blood counts and hepatic measures.

Why it mattered

Unlike early trials centered mainly on relapses, MSCRG made sustained EDSS progression the primary clinical outcome.

Important limitation

Enrollment ended before every participant could complete 2 years, producing variable follow-up and making the 104-week estimate dependent on time-to-event methods.