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Interferon-Beta-1b Appears More Effective in Preventing Multiple Sclerosis Relapse than Interferon Beta-1a

TORONTO, ON -- February 15, 2002 -- The latest data from the Independent Comparison of Interferon (INCOMIN) trial show that the benefits associated with interferon-beta-1b (Betaseron) are becoming more pronounced with time when compared to interferon-beta-1a (Avonex).

Professor Luca Durelli, Chief, Multiple Sclerosis Centre of University Department of Neurosciences, Turin, Italy and principle investigator of the trial, was in Toronto to share the latest findings.

INCOMIN was conducted independently of the pharmaceutical industry and was funded by the Multiple Sclerosis Association of Italy and the Italian Ministry of Health. It is comparing interferon-beta-1b and interferon beta-1a, the two most widely used multiple sclerosis (MS) medications in the world. The full two-year study was conducted from June 1999 until June 2001.

INCOMIN is a prospective, randomised, long-term multi-centre study on 188 people with relapsing-remitting MS. Patient randomisation to treatment arms was performed by independent statisticians with allocation concealment. The clinical evaluation was conducted on an open-label basis, while magnetic resonance imagine (MRI) scans were analysed blind of treatment used.

The two-year results revealed clinically relevant differences of between 42 to 56 percent in the benefit of the two medications and found that the beneficial effects of interferon beta-1b become more pronounced over time when compared to interferon beta-1a.

The primary clinical endpoint of the INCOMIN study - the number of relapse-free patients - showed the significant advantages of treatment with interferon beta-1b over interferon beta-1a during the two year period.

Specifically, the proportion of relapse-free patients at two years was 51 percent in the interferon beta-1b group versus 36 percent in the interferon beta-1a group (P=0.036). This means a 42 percent increased probability that patients treated with interferon beta-1b will remain free from relapses compared to those treated with interferon beta-1a.

The treatment benefit was particularly pronounced in the second year of the study, with 69 percent of the patients receiving interferon beta-1b remaining relapse free, compared with 45 percent of those receiving interferon beta-1a (P=0.001) and representing a 47 percent increased probability that patients treated with interferon beta-1b would remain free from attacks. These results underline the importance of conducting studies for a sufficient time in order to provide robust results.

In addition, progression of the disease -- defined as a worsening of 1.0 or more on the EDSS scale, confirmed after six months and maintained until the end of the follow-up -- was significantly slower in patients treated with interferon beta-1b, with 14 percent of patients worsening compared with 30 percent in those treated with interferon beta-1a: a relative risk reduction of 56 percent in favour of interferon beta-1b (P=0.005).

The study's other primary endpoint -- the number of patients without new T2 lesions as detected by MRI -- reinforced those clinical findings. Of the patients receiving interferon beta-1b over 24 months, 55 percent were free of new T2 lesions in the brain compared with only 26 percent of those on interferon beta-1a: a relative increase of 112 percent in favour of interferon beta-1b (P-0.0003).

Lastly, MS lesion activity was also significantly higher in patients receiving interferon beta-1a, with 75 percent showing disease activity by MRI, compared with just 49 percent of those on interferon beta-1b (P=0.0008).

"Our two year study provides a clinically relevant result in terms of guiding prescribing choice. There is now clear evidence that high dose and frequent therapy with interferon beta-1b is superior to the current dosing of once weekly with interferon beta-1a. We can clearly see that all beta interferon regimens are not the same," said Dr. Durelli.

SOURCE: GCI Group

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