When you develop NABS, the interferons are worthless. Or that was the case with Gary. He was on Betaseron and did okay with it. But after about 2 years, he went into a series of attacks. When he stopped the Betaseron altogether, he went into high gear with attacks. Bad ones every 4-6 weeks.
Perhaps I've misunderstood what you've written, but it seems that there may have been some positive effect from the interferon-beta as the attacks were worse after stopping it. Have you considered another interferon? For further discussion, Betaseron appears to have the highest tendency to produce neutralizing antibodies out of the three different interferon-beta preparations. I've discussed the reasons for this in an earlier thread
and the principle factor is likely to be due to the fact that Betaseron is produced in bacteria. Here's a link to a research article
which discusses the difference in neutralizing antibody response between the different interferon-betas.
NABs developed during the first three months of treatment and continued to develop until month 18. Over 18 months of treatment, the risk of being persistent NAB+ was 31% for Betaferon, 15% for Rebif, and 2% for Avonex (Betaferon versus Avonex, p = 0.001; Betaferon versus Rebif, p = 0.19; Rebif versus Avonex, p = 0.04). In all patients with one or more NAB+ samples, the risk of becoming NAB+ was 38% for Betaferon, 18% for Rebif, and 7% for Avonex (Betaferon versus Avonex, p = 0.0007; Betaferon versus Rebif, p = 0.10; Rebif versus Avonex, p = 0.07). At month 18, the prevalence of persistent NAB+ patients was 31.6% for Betaferon, 18.7% for Rebif, and 4% for Avonex.
Given this information, you may wish to consult with your doctor to see if Avonex might be an option in Gary's case. While there have been several reports in the PubMed database of cross reactivity in neutralizing antibodies, I have read one paper (which I apologize for not being able to locate in PubMed) which demonstrated that patients with neutralizing antibodies to Betaseron produce no neutralizing antibodies upon switching to Avonex after a months abstention from Betaseron. I know that I have this paper on file, but I'm away from my journal database right now and will post it later once I return.