Thank you for your inquiry.
You are correct that the studies that have looked at the long-term effect of immunotherapy after cessation of treatment have been of three years or more to the best of my knowledge (1-4). There is a dearth of information that I am aware of related to shorter courses when one refers to standard subcutaneous immunotherapy (not employing adjuvants such as tyrosine assisted or polymerized vaccines). There is one study, however, in children sensitive to house dust mites that showed short term (12 month) immunotherapy was associated with a greater rate of relapse than treatment given for more than three years (3).
So, from available data, I think we can assume, as one would expect, that the rate of relapse diminishes in relationship to the duration of treatment, but I do not think we have enough data to delineate the ideal duration of therapy in this regard.
However, because I cannot answer your question specifically, I am going to ask Dr. Harold Nelson, who as you know is an international authority in immunotherapy, to see if he has more information which may be of help. When I receive Dr. Nelson’s comments, I will forward them to you.
Thank you again for your inquiry.
1) Mosbech H, Osterballe O. Does the effect of immunotherapy last after termination of treatment? Follow-up study in patients with grass pollen rhinitis. Allergy 1988;43:523-529.
2) Jacobsen L, Nuchel Petersen B, Wihl JA, Lowenstein H, Ipsen H. Immunotherapy with partially purified and standardized tree pollen extracts. IV. Results from long-term (6-year) follow-up. Allergy 1997;52:914-920.
3) Des Roches A, Paradis L, Knani J, et al. Immunotherapy with a standardized Dermatophagoides pteronyssinus extract. V. Duration of the efficacy of immunotherapy after its cessation. Allergy 1996;51:430-433.
4) Stephen R. Durham, M.D., Samantha M. Walker, R.N., Eva-Maria Varga, M.D., Long-Term Clinical Efficacy of Grass-Pollen Immunotherapy N Engl J Med 1999; 341:468-475.
Phil Lieberman, M.D.
We have received a response from Dr. Harold Nelson regarding your Ask the Expert inquiry. Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.
Response from Dr. Harold Nelson:
The closest to answering the question is a study from Jean Bousquet (Des Roches A, et al. Immunotherapy with a standardized Dermatophagoides pteronyssinus extract. V. Duration of the efficacy of immunotherapy after its cessation). Allergy 1996;51:430-3). They treated asthmatics with HDM extract until they were asymptotic off treatment, then stopped and observed them for 3 years for evidence of a relapse. In those who received at least 3 years immunotherapy relapse occurred in 29% and in those receiving less than 3 years immunotherapy relapse occurred in 69%. Thus there was a significant correlation (p = 0.04) between duration of immunotherapy and persistent remission. On the other hand, 31% had persisting benefit despite less than 3 years of immunotherapy, some as little as one year.