PQ Grass: Convenient Symptom Relief in Seasonal Allergic Rhinitis, With Mohamed Shamji, PhD

PQ Grass 27600 SU, a chemically modified allergen preparation delivering just 6 subcutaneous injections pre-seasonally has demonstrated both clinically meaningful symptom reduction and broad immune tolerance induction according to new data presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2026 Annual Meeting held in Philadelphia, Pennsylvania, by Mohamed Shamji, PhD, Professor of Immunology and Allergy at Imperial College London and secretary general at European Academy of Allergy and Clinical Immunology.

The data come from pooled analyses across 2 clinical trials, PQG309 and PQG306, evaluating PQ Grass 27,600 SU (a polymerized, chemically modified extract of 13 grass species) in patients with seasonal allergic rhinitis, with or without asthma (n = 75; PQ Grass, n = 40; placebo, n = 35). To discuss the findings and their implications for the future of allergen immunotherapy, we sat down with Shamji during the meeting to learn more about the clinical meaningfulness of the study findings. The study yielded a 22.5% improvement (P <.00004) in the Combined Symptom Medication Score over placebo in a large AIT trial, its primary end point, atop a placebo response that itself commonly reaches 50%, meaning patients are experiencing roughly a 74% total reduction in symptoms — from 6 injections, with a adherence burden that bears no comparison to the 60-clinic-visit commitment of conventional 3-year subcutaneous or daily sublingual immunotherapy.

Mechanistically, PQ Grass induced robust systemic increases in grass pollen-specific blocking antibodies — sIgG (P <.001), sIgG4 (P <.001), sIgA1 (P <.001), and sIgA2 (P <.01) compared to placebo, measured both pre- and post-pollen season. Functionally, serum from treated patients significantly inhibited allergen-IgE complex binding to B cells pre-season (P <.001) and post-season (P <.01). At the cellular level, PQ Grass suppressed proliferation of both Th2 (P <.05) and Th2A (P <.05) effector subsets, with trends toward reduced Tfh and IL-21+ Tfh cell proliferation and a positive trend in memory Treg induction — together painting a tolerogenic profile consistent with sustained clinical benefit and supporting PQ Grass as a viable accelerated-course alternative to conventional immunotherapy schedules.

“Patients only have 6 shots, and they really feel better. They have reduced symptoms during the pollen season. They take less risky medications like antihistamine or nasal steroids. And I think that's very important and very meaningful for the patients,” Shamji said.

Shamji’s disclosure information was not available.

Reference

Layhadi J, Starchenka S, de Kam PJ, et al. PQ Grass 27600 SU effectively induces tolerogenic properties through modulation of humoral and cellular immune responses for the treatment of seasonal allergic rhinitis. Presented at: AAAAI 2026 Annual Meeting, February 27-March 2, Philadelphia, Pennsylvania. Abstract #L77