Allergy and its related symptoms are a major problem worldwide and SLIT (sublingual immunotherapy) attracts physicians and patients due to its long-lasting effects and its application for both prophylactic and therapeutic usages. However, the existing SLITs require a long administration period of 3~5 years to elicit efficacy and despite this, some patients remain non-responsive and/or show little or no improvement due to poor adherence and delayed or weak onset of efficacy. HSO-001 is being developed to address these needs by enhancing efficacy and shortening the treatment duration while improving safety and patient acceptability.