PRISMS

PRISMS* STUDY

One of the ways to test the effectiveness of a drug is to test against a placebo – a treatment that has no active medicine. A placebo-controlled study is a standard type of study required by the Food and Drug Administration (FDA) in the drug approval process. The placebo is used by one group of patients while the test drug is used by another group. The potential candidates are placed into one of the two groups at random and no one (neither the patients nor the treating physicians) knows what treatment any patient is receiving. This design eliminates bias and enables researchers to determine whether or not the test drug is truly effective in treating an illness. Here are the results of a study that compared Rebif^® (interferon beta-1a) to placebo.

Rebif: Proven Effective in a Placebo-Controlled Study

The PRISMS study is the largest placebo-controlled study of interferon beta-1a ever conducted in relapsing-remitting MS (RRMS):

• Studied the effects of Rebif (interferon beta-1a) at two doses: 44 mcg and 22 mcg, injected subcutaneously (under the skin) three times per week (tiw).
• Studied against placebo (inactive injections) for two years.
• Included 560 people with RRMS.
• Results were used to obtain approval of Rebif in the U.S.

Two-year results of the PRISMS study

Overall, the people taking Rebif at 44 mcg three times a week by subcutaneous injection had the best results in terms of effectiveness.

Rebif effectively reduced MRI lesions relative to placebo treatment

People in the study underwent MRI scans twice a year to assess the effect of Rebif versus placebo:

• Rebif 44 mcg three times per week (tiw) reduced the median number of active T2 lesions by 78%.
• Rebif 44 mcg tiw reduced the median number of combined unique active lesions by 88%.
• Rebif 44 mcg tiw reduced amount of total T2 lesion area by 3.8% from baseline at two years.

The exact correlation between MRI findings and the current or future clinical status of patients, including disability progression, is unknown.

Rebif effectively reduced relapses relative to placebo treatment

The number of relapses was the primary endpoint of the study, showing:

• People on Rebif were more likely to be relapse-free — 32% of those on Rebif did not have a relapse at all during the study, whereas 16% of patients on placebo remained relapse-free.
• When relapses occurred, there were fewer with Rebif — 32% fewer for people taking Rebif than for those taking placebo.
• When relapses did occur, on average, Rebif:
  • more than doubled the median time to first relapse
  • reduced the need for MS-related steroid treatments by 46%
  • reduced the need for MS-related hospitalizations by 48%

Rebif effectively delayed disability progression relative to placebo treatment

• Only 26% of people on Rebif had disability progression, whereas 37% of those taking placebo progressed.
• Rebif was proven to nearly double the time to progression of disability (21.3 months for Rebif vs. 11.9 months for placebo).

Rebif was found to have a manageable safety profile relative to placebo treatment

• The most common side effects were flu-like symptoms and injection site reactions, which are experienced by most patients beginning therapy but which usually lessen over time, and are generally mild to moderate and rarely a cause for discontinuation of therapy.
• Other side effects more common in people on Rebif were lowered white blood cell counts and increased liver enzyme values. Regular laboratory tests are recommended to monitor for these side effects since symptoms are not always obvious (e.g., yellowing of the skin, bruising, tiredness).
• Depression was reported in 24% of people taking Rebif and in 28% of people taking placebo.