Aug 30, 2002
Among the available interferon-beta preparations, Avonex appears least likely to induce the formation of neutralizing antibodies in patients with multiple sclerosis (MS), according to a report in the August Journal of Neurology, Neurosurgery, and Psychiatry.
Patients who develop neutralizing antibodies (NAB) to interferon-beta (IFN-beta) may experience less therapeutic efficacy with such treatment, the authors explain.
Dr. A. Bertolotto and colleagues from Universita di Torino-Regione Piemonte in Orbassano, Italy, examined the incidence and prevalence of NABs in serum samples from 125 MS patients who were treated with Betaferon, Avonex, or Rebif formulations of IFN-beta for 6 to 18 months. NABs were measured using a single, sensitive assay under controlled conditions in one central laboratory.
Of 21 patients who developed NABs, 19 (90%) developed them during the first year of treatment, the report indicates, and NABs were detected in most of those patients (84%) within the first 9 months of treatment.
The risk of developing antibodies was highest with Betaferon (31%), lower with Rebif (15%), and lowest with Avonex (2%), the researchers note, and the risk of being persistently NAB-positive was significantly lower for Avonex than for the other two formulations.
Similarly, the prevalence of NABs was significantly higher in Betaferon-treated patients (31.6%) than in Avonex-treated patients (4%) at month 18, the results indicate, and significantly higher for all time points after 3 months of treatment. The prevalence of NAB-positivity was intermediate for Rebif.
"The rank of relative risk [of developing NABs] was found to be Betaferon is greater than or equal to Rebif which is greater than Avonex," the authors conclude. "Hence, the relative risk of developing NABs should be considered when selecting the appropriate IFN-beta treatment, both for newly diagnosed MS and for those already receiving treatment for MS."
"Once a patient has persistent neutralizing antibodies, switching to another interferon beta is illogical, as the antibodies cross react," writes Dr. A. J. Coles from Addenbrooke's Hospital in Cambridge, UK in a related editorial.
"Strategies to prevent neutralizing antibodies may include using a tolerising drug to initiate treatment, concomitant immunosuppression, mucosal routes of administration, and either much higher or lower doses," comments Dr. Coles.
J Neurol Neurosurg Psychiatry 2002;73:148-153,110-111.
© 2002 Reuters Ltd