Cutting edge of oral immunotherapy (OIT): Differences between Japan and overseas

Abstract

Oral immunotherapy (OIT) is widely performed in Japan, Europe, and north America, although some differences exist between Japan and other countries regarding target of subjects and methods.

In other countries, an oral food challenge (OFC) is not always conducted before OIT. Furthermore, stepwise OFC, which begins with a low-dose to evaluate threshold, has rarely been performed. The severity of participants differed from that in Japan.

Although OIT combined with anti-IgE antibodies has improved safety overseas, the majority of efficacy is desensitization, rather than sustained unresponsiveness (SU).

Palforzia is covered by health insurance in Europe and the United States; however, SU has not been evaluated, and issues, such as safety and continuation of treatment, remain unresolved. Currently, there are no prospects for Palforzia's approval in Japan.

In Japan, OIT is typically administered at a low maintenance dose, which has safely induced low-dose desensitization. Long-term low-dose OIT reaches to medium- and full-dose SU over time, and provides a preventive effect against accidental ingestion.

Although safety has improved under the new protocol, achieving SU in the short term remains nearly impossible. It is important to adjust the protocol individually and to explain necessity of long-term treatment to subjects and their guardians.