Heterogeneity of antibody responses among clinical responders during grass pollen sublingual immunotherapy

BACKGROUND

During allergen-specific sublingual immunotherapy (SLIT), the relevance of changes in specific IgE and IgG antibody titres to treatment efficacy remains to be evaluated at an individual patient level.

OBJECTIVE

To investigate whether antibody responses can be used as biomarkers for SLIT efficacy.

METHODS

Comprehensive quantitative, qualitative and functional analyses of allergen-specific IgA, IgE, IgG1-4 and IgM responses were performed using purified Phl p 1 to 12 allergens in sera, saliva and nasal secretions from 82 grass pollen allergic patients. These patients were enrolled in a randomized, double-blind placebo-controlled study and assessed in an allergen challenge chamber (ClinicalTrials.gov NCT00619827). Antibody responses were monitored in parallel to clinical responses before and after daily sublingual treatment for 4 months with either a grass pollen or a placebo tablet.

RESULTS

A significant mean improvement (i.e. 33-40.6%) in rhinoconjunctivitis total symptom scores was observed in SLIT recipients, irrespective of their baseline patterns of IgE sensitization (i.e. narrow, intermediate, broad) to grass pollen allergens. SLIT did not induce any de novo IgE sensitization. Clinical responders encompassed both immunoreactive patients who exhibited strong increases in titres, affinity and/or blocking activity of grass-pollen-specific IgGs (representing 17% of treated patients), as well as patients with no detectable antibody responses distinguishing them from the placebo group. No significant changes were detected in antibody titres in saliva and nasal washes, even in clinical responders.

CONCLUSIONS AND CLINICAL RELEVANCE

Sublingual immunotherapy with a grass pollen tablet is efficacious irrespective of the patients' baseline sensitization to either single or multiple grass pollen allergens. Seric IgG responses may contribute to SLIT-induced clinical tolerance in a fraction (i.e. 17%) of patients, but additional immune mechanisms are involved in most patients. Consequently, antibody responses cannot be used as a marker of SLIT efficacy at an individual patient level.

Changes in basophil activation during grass-pollen sublingual immunotherapy do not correlate with clinical efficacy

BACKGROUND

Biomarkers predicting the safety and efficacy of sublingual immunotherapy (SLIT) remain to be established.

METHODS

Eighty-nine patients with allergic rhinoconjunctivitis to grass pollen received either a placebo or five-grass-pollen daily tablet sublingually for 4 months. Following exposure in an allergen challenge chamber, clinical responders and nonresponders were identified individually by evaluating their rhinoconjunctivitis total symptom score (RTSS). Activation of peripheral blood basophils was measured by cytofluorometry before and after 2 or 4 months of immunotherapy, based on CD203c surface expression following allergen stimulation.

RESULTS

Patients receiving the grass-pollen tablet had a relative mean improvement of 29.3% vs placebo in the average RTSS after 4 months of SLIT (P < 0.0003). No significant changes in basophil activation were noticed after 2 or 4 months of SLIT despite induction of specific IgGs. Among individual clinical responders, basophil activation was either decreased, increased, or unmodified during SLIT. Levels of basophil activation prior to immunotherapy were not predictive of local adverse reactions associated with immunotherapy. A moderate association was found between basophil activation and allergen-specific IgE levels, skin reactivity, or RTSS, suggesting that the former is, to some extent, indicative of disease severity. As such, patients with the highest level of basophil activation before treatment were more likely to benefit clinically from SLIT.

CONCLUSIONS

Allergen reactivity of peripheral blood basophils is not a biomarker for adverse events or early onset of clinical responses to SLIT.

Safety of sublingual-swallow immunotherapy in children and adults

BACKGROUND

Immunotherapy is an established treatment of allergic diseases. The safety of this treatment, particularly when administered without direct medical surveillance, as in the case of the sublingual-swallow route needs to be established. The aim of this paper is to review the safety of the sublingual-swallow immunotherapy as reported in eight double-blind, placebo-controlled trials carried out in France, Italy and Greece.

METHODS

Six hundred and ninety subjects, 472 adults and 218 children, took part in trials of specific immunotherapy (SIT) for the treatment of rhinoconjunctivitis and/or asthma. Three hundred and forty-seven patients received SIT and 343 patients received placebo. Treatment with specific immunotherapy with allergen extracts or placebo was administered using the sublingual-swallow technique. The allergens administered were grass, ambrosia, parietaria and olive pollens, and mites. The daily dose taken during maintenance therapy ranged from 100 to 300 IR (index of reactivity) and cumulative doses ranged from 4,500 to 104,000 IR. Treatment duration ranged from 4 months to 2 years. Adverse events reported either spontaneously by the patient or on direct questioning by the investigator were analysed.

RESULTS

One hundred and forty-five unusual events were reported in the subjects receiving active SIT and 79 in those receiving placebo (p < 0.001). Of these 85 were children aged 15 years or less (50 received active SIT, 35 placebo) and 139 were adults (95 received SIT, 44 placebo). Unusual events involving the buccal cavity (61 SIT, 13 placebo) and the gastro-intestinal tract (47 SIT, 15 placebo) were significantly more frequent in the SIT-treated patients (p < 0.001). Wheezing (9 SIT, 21 placebo) was more frequent in the placebo-treated patients (p < 0.05). There were no differences in the frequency of unusual events between adults and children and in the frequency of events involving other body systems. No event was reported as serious. Two events reported as laryngeal oedema were not considered to be accurate descriptions.

CONCLUSIONS

No serious adverse event was reported in the studies monitored, confirming the good safety profile of the sublingual-swallow method both in children and adults with rhinitis or moderate asthma.

Sublingual-swallow immunotherapy (SLIT) with a standardized five-grass-pollen extract (drops and sublingual tablets) versus placebo in seasonal rhinitis

BACKGROUND

Recent studies have demonstrated the efficacy of sublingual-swallow immunotherapy (SLIT) in seasonal and perennial rhinitis. Sublingual administration of solutions is not convenient for all patients. The aim of the study was to evaluate the efficacy and safety of immunotherapy administered sublingually, initially as drops, and then as tablets during maintenance therapy.

METHODS

A total of 126 patients with grass-pollen seasonal rhinitis were included in this double-blind, randomized, placebo-controlled trial. During the progression of doses phase, the five-grass extract was given as sublingual drops from 1 to 100 IR/ml. Once the 100 IR dose was reached, the drops were replaced by a single 100-IR sublingual tablet per day.

RESULTS

Throughout the grass-pollen season, patients in the active treatment group had significantly lower (P < 0.05) total conjunctivitis and ocular redness scores. Rhinitis symptoms were not significantly different between the two groups. Patients given the active treatment were significantly (P < O.02) less likely to have asthma symptoms. The global medication score showed no significant difference between the two groups. A highly significant difference in favor of the active treatment group was seen in inhaled salbutamol use (P < 0.01).

CONCLUSIONS

Clinical benefits achieved during the present study included significant improvements in conjunctivitis symptoms and prevention of asthma symptoms. The overall safety profile of the active treatment (drops or tablets) was good.

Sublingual-swallow immunotherapy (SLIT) with a standardized five-grass-pollen extract (drops and sublingual tablets) versus placebo in seasonal rhinitis

BACKGROUND

Recent studies have demonstrated the efficacy of sublingual-swallow immunotherapy (SLIT) in seasonal and perennial rhinitis. Sublingual administration of solutions is not convenient for all patients. The aim of the study was to evaluate the efficacy and safety of immunotherapy administered sublingually, initially as drops, and then as tablets during maintenance therapy.

METHODS

A total of 126 patients with grass-pollen seasonal rhinitis were included in this double-blind, randomized, placebo-controlled trial. During the progression of doses phase, the five-grass extract was given as sublingual drops from 1 to 100 IR/ml. Once the 100 IR dose was reached, the drops were replaced by a single 100-IR sublingual tablet per day.

RESULTS

Throughout the grass-pollen season, patients in the active treatment group had significantly lower (P < 0.05) total conjunctivitis and ocular redness scores. Rhinitis symptoms were not significantly different between the two groups. Patients given the active treatment were significantly (P < O.02) less likely to have asthma symptoms. The global medication score showed no significant difference between the two groups. A highly significant difference in favor of the active treatment group was seen in inhaled salbutamol use (P < 0.01).

CONCLUSIONS

Clinical benefits achieved during the present study included significant improvements in conjunctivitis symptoms and prevention of asthma symptoms. The overall safety profile of the active treatment (drops or tablets) was good.

Sublingual-swallow immunotherapy (SLIT) in patients with asthma due to house-dust mites: a double-blind, placebo-controlled study

A double-blind, placebo-controlled study was carried out in 85 patients with a well-documented history of perennial asthma caused by house-dust mites. Patients received either placebo or sublingual immunotherapy (SLIT) with a standardized Dermatophagoides pteronyssinus (DP)-D. farinae (DF) 50/50 extract. After a run-in period, patients received increasing doses up to 300 IR every day for 4 weeks and then three times a week for the following 24 months. The cumulative dose was about 104000 IR, equivalent to 4.2 mg Der p 1 and 7.3 mg Der f 1. Symptom and medication scores and respiratory function were assessed throughout the trial. Serum specific IgE and IgG4 were determined before SLIT (t0) and after 6 (t1), 11 (t2), 17 (t3), and 25 months (t4) of SLIT. Mite exposure was evaluated at t0, t2, and t4 by semiquantitative guanine determinations. Patients aged 15 years and older were asked to assess their quality of life (QoL) by completing the SF20 (Short Form Health Status Survey) plus two items at t0, t2, and t4. Use of inhaled corticosteroids and beta2-agonists was significantly decreased after 25 months of treatment in both groups (P<0.03). SLIT patients showed significant improvements in respiratory function at t4 (% predicted FEV1 (P = 0.01), VC (P = 0.002), morning (P = 0.01) and evening (P = 0.03) PEFR), and reduction in daytime asthma score (P = 0.02). In the SLIT group, the post-treatment PD20 was 1.75 times higher than the baseline value. There was no change in PD20 in the placebo group. Compared to the placebo group, the SLIT group showed a significant increase in specific IgE DP(P = 0.05), IgE DF(P = 0.02), IgG4 DP(P = 0.001), and IgG4 DF (P = 0.001) levels after SLIT. QoL scores were similar in both groups at t0 and t2. At t4, all scores were better in the SLIT group than in the placebo group, with the differences being most marked for the general perception of health (P = 0.01) and physical pain (P = 0.02). Adverse events were similar in the two groups. This study shows that SLIT in house-dust-mite-related asthma has a good safety profile and improves respiratory function, bronchial hyperreactivity, and QoL.