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Avonex, manufactured by Biogen, is a form of beta interferon (interferon beta, IFN-b) used to modify the course of multiple sclerosis. While not a cure, Avonex has been shown in clinical trials to reduce the average relapse rate in people with the  relapsing-remitting multiple sclerosis form of the disease. That doesn't mean that it reduces the relapse rate for all the trial volunteers, just that averaged over the entire volunteer population, the relapse rate is reduced.

Avonex is a form of beta interferon known as interferon beta-1a. It is identical to the naturally occurring protein found in the human body. It is manufactured by extracting the drug from Chinese hamster ovary cells. Avonex is the same substance as Rebif but administered differently (30 mcg, intra-muscularly, once a week as against 22 mcg or 44 mcg, sub-cutaneously, 3 times a week for Rebif). Avonex is usually given in the large muscles of the thigh, upper arm, or hip.

Here is a table of clinical trials of Avonex.
Efficacy of Avonex in Relapsing-Remitting Multiple Sclerosis
Trial Name Brief Description Results Reference
The Multiple Sclerosis Collaborative Research Group (MSCRG) The pivotal multi-centre phase III Avonex study published in 1996. 301 people with RRMS were compared with placebo over 3 years. Avonex reduced annual relapse rate from 0.90 in the placebo group to 0.61. It also delayed time to sustained EDSS progression and reduced burden of disease under MRI. Ann Neurol 1996 Mar; 39(3) : 285-94

Neurology 1999; 53 : 139

Controlled High-Risk Subjects Avonex Multiple Sclerosis Prevention Study (CHAMPS). Does Avonex reduce conversion to clinically definite MS in people who have only had a single demyelinating event? The study population of 384 was divided into those with optic neuritis (ON), brainstem-cerebellar events and those with spinal cord syndrome. The study lasted up to  for up to 3 years. All three groups showed a reduction in conversion to clinically definite MS. Those with ON at a ratio of 0.58 compared with placebo, those with brainstem-cerebellar events at 0.40 and those with spinal cord syndrome at 0.30. J Neuroophthalmol 2001 December; 21(4) : 292-295

Ann Neurol 2002 Apr; 51(4) : 481-490

Double-blind randomized multicenter dose-comparison study of Avonex The initial study involved 802 people with EDSS scores 2.0-5.5. Half the group received 30 mcg Avonex intra-muscularly once a week and the other group received 60 mcg. The trial has been extended to run over 4 years for 491 of volunteers. In a press release in November 2000, Biogen reported that after two years of the trial there was no difference in relapse rate between the two groups. In a presentation to the AAN conference in April 2002, two of the study's researchers (Ludwig Kappos and Michel Clane) said that there was still no difference between the two groups but that the efficacy of Avonex was sustained over 4 years. AAN conference presentation, April 2002

Mult Scler 2001 Jun;
7(3) : 179-83

Comparative trials involving Avonex
Trial Name Brief Description Results Reference
Every-other-day interferon beta-1b versus once-weekly interferon beta-1a for multiple sclerosis (INCOMIN). Comparative 2-year, prospective, randomised, multicentre study. 188 patients with RRMS were assigned to interferon beta-1b (n=96) or interferon beta-1a (n=92). Interferon beta-1a 30 microg was administered once a week (Avonex regime), interferon beta-1b 250 microg (Betaseron regime) was administered on alternate days. Primary outcome measures were the proportion of patients free from relapses and new MRI T2 lesions. 51% on interferon beta-1b remained relapse-free compared with 36% on interferon beta-1a. 55% on interferon beta-1b had no new T2 lesions compared 26% on interferon beta-1a. Lancet 2002 Apr 27;359(9316):1453-60
Open-label treatment trial to compare the effect of IFNb-1a (Avonex), IFNb-1b (Betaseron), and glatiramer acetate (Copaxone) on the relapse rate in RRMS 12 month (18 months of follow-up) prospective, non-randomized, open-label trial with 156 volunteers (33 no treatment, 40 Avonex, 41 Betaseron and 42 Copaxone Average relapses per year:
Copaxone - 0.49;
Betaseron 0.55;
Avonex - 0.81;
Untreated - 1.02.
The Avonex reduction was not statistically significant
Eur J Neurol 2001 Mar ; 8(2): 141-8

Mult Scler 2001 Dec; 7(6) : 349-53

Evidence for Interferon Dose-Response: European-North American Comparative Efficacy (EVIDENCE) Multicentre, randomised, assessor-blinded trial. 677 patients with RRMS - 339 received Rebif, 44 mcg three times weekly and 338 received Avonex, 30 mcg once weekly for 48 weeks. After 24 weeks, 74.9% with Rebif remained relapse-free compared with 63.3% on Avonex. Rebif users had an average of 0.8 new lesions per scan while Avonex had an average of 1.2 new lesions per scan. Coyle PK et al - speakers' abstracts, AAN 54th Annual Meeting, April 2002

Sharief MK - speakers' abstracts, AAN 54th Annual Meeting, April 2002

Coyle PK. J Neurol Sci 2001;187 Suppl 1:S436

Efficacy of Avonex in Secondary Progressive Multiple Sclerosis
Trial Name Brief Description Results Reference
International Multiple Sclerosis Secondary Progressive Avonex Clinical Trial (IMPACT) Phase III multi-centre trial of 426 patients with SPMS and EDSS score of 3.5-6.5 were given 60 mcg of Avonex or placebo in a weekly intramuscular injection. No benefit was seen on clinical measures driven by ambulation. However, the Avonex treated group had a 40% decrease in the median disability progression over the placebo group, a 33% decrease in relapse rate and a reduction of burden of disease under MRI. Avonex - SPMS
      Avonex - PPMS

Interferon beta1a (Avonex) treatment in multiple sclerosis: similarity of effect on progression of disability in patients with mild and moderate disability.

Biogen provides support for Phase IV investigator-run trials evaluating AVONEX® (Interferon beta-1a) in combination with other therapies.

Impact of interferon beta-1a on neurologic disability in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG) - Neurology 1997 49: 358-363.

Neutralizing and Binding Antibodies to IFN-beta: Relative Frequency in Relapsing-Remitting Multiple Sclerosis Patients Treated with Different IFN-beta Preparations.

Both paracetamol and ibuprofen are equally effective in managing flu-like symptoms in relapsing-remitting multiple sclerosis patients during interferon beta-1a (AVONEX) therapy.

Interferon beta-1a in children with multiple sclerosis is well tolerated

Interferon-beta (INF-beta) antibodies in interferon-beta1a- and interferon-beta1b

More information about Avonex including comparative information between the various disease modifying treatments for multiple sclerosis can be found by following these links:
ABC treatments
interferon beta

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Avonex links:
NMSS - Medications Commonly Used In MS - Avonex
Biogen pages on Avonex (Interferon beta-1a) (PDF format)

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