Two-Year Results Show Clinical Benefits Are Incremental Over Time

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October 4, 2001  8:36am
Source: PR Newswire

TURIN, Italy, Oct 4, 2001 /PRNewswire via COMTEX/ -- The following press release is being issued from the desk of Professor Luca Durelli, Chief, MS Centre of University Department of Neurosciences, Turin, Italy:

Results from the Independent Comparison of Interferon (INCOMIN) trial released at this week's Italian Neurological Society meeting(1) reveal clinically relevant differences of between 42 to 56 per cent in the benefit of interferons used to treat multiple sclerosis (MS) when studied for a significant period, and that the beneficial effects of interferon beta-1b become more pronounced over time when compared to interferon beta-1a.

Professor Luca Durelli, Chief, MS Centre of University Department of Neurosciences, Turin, Italy, and principle investigator of the INCOMIN trial said: "The final results from the INCOMIN study confirm the interim, one-year data presented earlier this year at the annual meetings of the American Academy of Neurology and European Society of Neurology, where the study was granted with an award(2,3). Over the full two-year duration of the INCOMIN study, interferon beta-1b continues and extends the benefits of treatment over interferon beta-1a on the first clinical outcomes we have analyzed in relapsing-remitting MS (RRMS)."

"Similar effects have been seen in other clinical studies, but those trials have been short term in the context of a chronic disease that may have a 20-25 year course," continued Professor Durelli. "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."

The prospective, randomized, multi-center study on 188 people with relapsing-remitting MS was supported by research grants from the Multiple Sclerosis Association of Italy and the Italian Ministry of Health and was conducted independently of the pharmaceutical industry. Patient randomization to treatment arms was performed by independent statisticians with allocation concealment. The clinical evaluation was conducted on an open-label basis, while MRI scans were analyzed blind of the treatment used.

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 a two-year period, with the clinical benefits for patients becoming more pronounced over time.

The proportion of relapse-free patients at two years was 51% in the interferon beta-1b group versus 36% in the interferon beta-1a group (P=0.036). This means a 42% increased probability that patients treated with interferon beta-1b remained free from relapses compared to those treated with interferon beta-1a (see Figure 1 attached).

The treatment benefit was particularly pronounced in the second year of the study, with 72% of the patients receiving interferon beta-1b remaining relapse free, compared with 49% of those receiving interferon beta-1a (P=0.001) and representing a 47% increased probability that patients treated with interferon beta-1b would remain free from attacks (see Figure 1). These results underline the importance of conducting studies for a sufficient time in order to provide a robust result.

In addition, progression of the disease -- defined as a worsening of 1.0 or more on the EDSS scale, confirmed after 6 months and maintained until the end of the follow-up -- was significantly slower in patients treated with interferon beta-1b, with 14% of patients worsening compared with 30% in those treated with interferon beta-1a: a relative risk reduction of 56% in favor of interferon beta-1b (P=0.005).

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

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

Treatment was discontinued due to lack of a clinical response by 10 patients receiving interferon beta-1a and by only 3 of those receiving interferon beta-1b.

Data for the other secondary endpoints are still being analyzed and the full data will be published in due course.

Commenting on the results, Professor Durelli said: "The full results will be published shortly, but these are important data that clearly differentiate between the beta interferon agents. The results prove that high, frequent dosing is very important and is superior to once-weekly dosing."

Note to Editors:

• Interferon beta-1a (Biogen) is given once weekly as an intramuscular injection of 30 microgram (6 MIU).