**2.3 Result of this study**

A total of seven infants were excluded from the study: three infants were excluded because their parents did not allow their children to receive suplatast tosilate, while four infants were excluded because they stopped attending the hospital for various reasons. As a result, there were 29 infants in the ketotifen group and 24 in the suplatast group. The clinical profile of each group is shown in the Table 1.


Table 1. Clinical profile

There were no significant differences between the two groups with respect to the sex ratio, age, time of onset of atopic dermatitis, number of days from onset to drug treatment. The mean age at the start of treatment was 365.5 ± 80.5 days in the 24 infants who received suplatast tosilate and 370.9 ± 78.7 days in the 29 who received ketotifen fumarate.

There were no differences between the suplatast group and the ketotifen group with respect to the total IgE level or the levels of specific IgE for house dust mite or Der P before treatment. However, the specific IgE levels for egg white and milk were significantly higher in the suplatast group.

The incidence of asthma was significantly lower in the suplatast group than the ketotifen group, with asthma occurring in five out of 24 patients from the former group (20.8%) vs. 19 out of 29 patients from the latter group (65.6%, p < 0.01). Additionally, the time from the start of drug treatment to the onset of wheezing among patients in whom asthma occurred was significantly longer in the suplatast group than the ketotifen group (p < 0.01, Fig. 1). The percentage of infants who were admitted to hospital for the treatment of asthma was significantly lower (p < 0.05) in the suplatast group (one out of 24 patients, or 4.2%) than in the ketotifen group (seven out of 29 patients, or 24.1%).

The initial wheezing episodes were plotted by the Kaplan–Meier method, and p-values were calculated with the log-rank test. Pearson's chisquared test was used to analyze the incidence of asthma. The Th1/Th2 ratio, total IgE level, and eosinophil count were compared between before and after treatment using the paired t-test. It was employed to determine the significance of differences between the two treatments. Results were expressed as the mean ± s.e., and p-values of <0.05 were considered to indicate statistical

A total of seven infants were excluded from the study: three infants were excluded because their parents did not allow their children to receive suplatast tosilate, while four infants were excluded because they stopped attending the hospital for various reasons. As a result, there were 29 infants in the ketotifen group and 24 in the suplatast group. The clinical

> Ketotifen group (n = 29)

> > female 7

Age (days) 370.9±78.7 365.5±80.5 0.728 Age at onset (days) 145.1±34.5 134.4±19.7 0.633

treatment (days) 225.8±69.4 231.0±77.7 0.837 Total IgE (IU/ml) 509.2±209.6 745.7±207.0 0.24 Egg IgE (Class) 2.50±0.26 3.36±0.31 0.0188 Milk IgE (Class) 2.09±1.87 3.69±0.37 0.0273 House dust mite IgE (Class) 1.25±0.49 1.56±0.59 0.814 Der P IgE (Class) 1.31±0.48 1.73±0.64 0.752

There were no significant differences between the two groups with respect to the sex ratio, age, time of onset of atopic dermatitis, number of days from onset to drug treatment. The mean age at the start of treatment was 365.5 ± 80.5 days in the 24 infants who received

There were no differences between the suplatast group and the ketotifen group with respect to the total IgE level or the levels of specific IgE for house dust mite or Der P before treatment. However, the specific IgE levels for egg white and milk were significantly higher

The incidence of asthma was significantly lower in the suplatast group than the ketotifen group, with asthma occurring in five out of 24 patients from the former group (20.8%) vs. 19 out of 29 patients from the latter group (65.6%, p < 0.01). Additionally, the time from the start of drug treatment to the onset of wheezing among patients in whom asthma occurred was significantly longer in the suplatast group than the ketotifen group (p < 0.01, Fig. 1). The percentage of infants who were admitted to hospital for the treatment of asthma was significantly lower (p < 0.05) in the suplatast group (one out of 24 patients, or 4.2%) than in

suplatast tosilate and 370.9 ± 78.7 days in the 29 who received ketotifen fumarate.

Suplatast group

Males 18,

(n = 24) p-value

female 6 0.942

**2.2.6 Statistical analysis** 

**2.3 Result of this study** 

profile of each group is shown in the Table 1.

No. of days from onset to drug

Table 1. Clinical profile

in the suplatast group.

Sex Males 22,

the ketotifen group (seven out of 29 patients, or 24.1%).

significance.

Fig. 1. Onset of wheezing during treatment with a Th2 cytokine inhibitor (suplatast tosilate) or a histamine H1-blocker (ketotifen fumarate).

The eosinophil count decreased significantly from 1.212 ± 174 to 679 ± 111/lL (p < 0.05) after 219 ± 42 days of suplatast treatment (n = 21), while no significant change was observed after 280 ± 44 days of ketotifen treatment (n = 19). The change after treatment was significantly larger (p < 0.01) in the suplatast group (-532.4 ± 120.0) compared with the ketotifen group (-2.1 ± 126.0) (Fig. 2). Although there was no significant change of the Th1/Th2 ratio after treatment in either the suplatast group (from 4.88 ± 1.07 to 6.76 ± 1.58%, n = 16) or the ketotifen group (from 10.00 ± 8.52 to 6.44 ± 1.88% n = 10), there was a significant difference of the ratio between the two groups (p < 0.05) (Fig. 3). However, there was no significant difference between the groups with respect to changes of the total IgE level (data not shown).

Fig. 2. Eosinophil count before and after treatment with suplatast tosilate (-532.4 ± 120.0) or ketotifen fumarate (-2.1 ± 126.0); \*p < 0.01 by the t-test.

Suplatast Tosilate for Prophylaxis of Pediatric Atopy 295

treatment in the suplatast group than in the ketotifen group, but neither drug decreased the serum IgE level. Based on the previous report that 3 or 6 months of treatment with suplatast tosilate decreased the serum levels of IgE and IL-4 in adults with perennial allergic rhinitis (26), we assessed the changes of parameters over a 6-month period in this study. The failure of suplatast tosilate to suppress IgE production may have been related to the low age of the subjects in the suplatast group (mean age at the start of treatment with suplatast: 365.5 days), because there is a gradual increase of tolerance to food allergens such as egg white and cow's milk, while sensitization to inhaled allergens like Der P and house dust mite shows a rapid increase at this age and infants with an atopic tendency show increased IgE synthesis at this age (27). Accordingly, we were not able to assess the efficacy of suplatast from the total IgE level. The Early Treatment of the Atopic Child (ETAC) study investigated the use of cetirizine, an H1-blocker like ketotifen for preventing the onset of asthma and found no significant overall benefit compared with the placebo, although asthma was prevented in patients sensitized to house dust mite or grass pollen (10). Our patients had high antibody titers for food allergens, but their mean baseline CAP RAST scores were 2 or less for both house dust mite and Der P. This suggests that suplatast was more effective than H1-blockers for patients who were not strongly sensitized to inhaled allergens. As we did not initially plan to assess changes of specific IgE levels in the present study, these parameters were only measured in a few patients after the start of treatment. Therefore, drawing firm conclusions is impossible, but we plan to investigate further whether suplatast has a similar effect to that of immunotherapy, which prevents the development of new allergies (e.g., suppresses reactions to inhaled allergens) (28). In the present study, we directed our attention to the Th1/Th2 ratio. At birth, the production of INF-c is very low and infants are in a state where the immune response is Th2 dominant. If IFN-c production increases during the 6 months after birth, the immune response will become Th1 dominant and the production of IL-4 will be inhibited, preventing the acquisition of an atopic predisposition. In an environment that does not cause induction of IFN-c, however, its level gradually increases with maturity, but IL-4 also continues to be produced until an atopic predisposition is acquired (29). Our preliminary study showed that persons with a strong atopic predisposition, who developed food allergies followed by atopic dermatitis, asthma, and allergic rhinitis, actually had a higher Th1/Th2 ratio than healthy subjects and had a Th1-Th2 balance skewed toward Th2 dominance (unpublished observation). Such findings suggest that there is a tendency for Th2 dominance in infancy and that an increase of inflammation due to eosinophils, etc. may lead to the eventual onset of asthma. Suplatast has been shown to inhibit the activity of eosinophils by in vitro and in vivo studies, including research performed using peripheral blood, sputum, and bronchial tissue specimens obtained by biopsy (12–14, 16, 17). In the present study, suplatast significantly decreased the peripheral blood eosinophil count compared with ketotifen. There have been several reports of a relationship between the onset of asthma and eosinophils. For example, Bromchoalveolar lavage fluid (BALF) levels of Eosimophilic Catiomic Protein (ECP) are higher in patients with childhood asthma than in those with infantile wheeze (30), and persons who subsequently develop asthma have more Eosimophil Granulocyte-2 (EG2)- positive cells in the

epithelium or lamina propria on bronchial biopsy than those who do not (31).

contribute to preventing the onset of asthma.

It appears that inhibition of the onset of asthma may be attributable to two factors, which are a decrease of the eosinophil count and a shift of the Th1/Th2 ratio toward Th1 dominance. The results of our study provide some corroboration for the hypothesis that inhibition of eosinophilic inflammation and improvement of the Th1/Th2 balance can

Fig. 3. Th1/Th2 ratio before and after treatment with suplatast tosilate (1.88 ± 1.57) or ketotifen fumarate (-3.56 ± 1.99); \*p < 0.05 by the t-test.

No adverse events and no laboratory abnormalities were observed in the suplatast group. Two episodes of sedation occurred in the ketotifen group, but these were transient and did not result in the discontinuation of therapy.

#### **2.4 Effectiveness of early intervention with a Th2 cytokine inhibitor**

Children with a family history of allergic disease are likely to have a predisposition to atopy and the processes leading to the development of such diseases may commence in utero. After birth, continuous exposure to certain food antigens may sequentially trigger allergic reactions that manifest as food allergies, atopic dermatitis, asthma, and allergic rhinitis. Such reactions are involved in the progression of allergic disease (24, 25). Treatment designed to suppress the exacerbation of allergic airway inflammation may potentially have an important role in the prophylaxis and management of these diseases.

We compared the inhibitory effect of suplatast tosilate and the H1-blocker ketotifen fumarate on the onset of asthma in patients with atopic dermatitis who were positive for egg-white or milk allergens. When ketotifen was previously tested in 121 infants with atopic dermatitis who were treated for a 1-yr period, it reduced the occurrence of asthma compared with placebo, and the subgroup of children with a high IgE level showed a significant benefit (9). After 24 months of treatment in the present study, however, asthma developed in 65.6% of the patients receiving ketotifen vs. only 20.8% of those treated with suplatast. To assess the prevention of progression to severe asthma, we analyzed the number of patients who required hospital treatment for their asthma. Seven out of 29 infants from the ketotifen group and only one out of 24 infants from the suplatast group were admitted to hospital for the treatment of asthma, with the percentage being significantly lower in the suplatast group. This finding suggests the possibility that suplatast can prevent progression of mild asthma to severe asthma.

To examine the systemic effects of suplatast (a Th2 cytokine inhibitor) vs. those of ketorifen (an antihistamine), the Th1/Th2 ratio, total IgE level, and eosinophil count were measured before and after treatment. As a result, the Th1/Th2 ratio was found to be significantly higher after

Fig. 3. Th1/Th2 ratio before and after treatment with suplatast tosilate (1.88 ± 1.57) or

**2.4 Effectiveness of early intervention with a Th2 cytokine inhibitor** 

important role in the prophylaxis and management of these diseases.

No adverse events and no laboratory abnormalities were observed in the suplatast group. Two episodes of sedation occurred in the ketotifen group, but these were transient and did

Children with a family history of allergic disease are likely to have a predisposition to atopy and the processes leading to the development of such diseases may commence in utero. After birth, continuous exposure to certain food antigens may sequentially trigger allergic reactions that manifest as food allergies, atopic dermatitis, asthma, and allergic rhinitis. Such reactions are involved in the progression of allergic disease (24, 25). Treatment designed to suppress the exacerbation of allergic airway inflammation may potentially have an

We compared the inhibitory effect of suplatast tosilate and the H1-blocker ketotifen fumarate on the onset of asthma in patients with atopic dermatitis who were positive for egg-white or milk allergens. When ketotifen was previously tested in 121 infants with atopic dermatitis who were treated for a 1-yr period, it reduced the occurrence of asthma compared with placebo, and the subgroup of children with a high IgE level showed a significant benefit (9). After 24 months of treatment in the present study, however, asthma developed in 65.6% of the patients receiving ketotifen vs. only 20.8% of those treated with suplatast. To assess the prevention of progression to severe asthma, we analyzed the number of patients who required hospital treatment for their asthma. Seven out of 29 infants from the ketotifen group and only one out of 24 infants from the suplatast group were admitted to hospital for the treatment of asthma, with the percentage being significantly lower in the suplatast group. This finding suggests the

possibility that suplatast can prevent progression of mild asthma to severe asthma.

To examine the systemic effects of suplatast (a Th2 cytokine inhibitor) vs. those of ketorifen (an antihistamine), the Th1/Th2 ratio, total IgE level, and eosinophil count were measured before and after treatment. As a result, the Th1/Th2 ratio was found to be significantly higher after

ketotifen fumarate (-3.56 ± 1.99); \*p < 0.05 by the t-test.

not result in the discontinuation of therapy.

treatment in the suplatast group than in the ketotifen group, but neither drug decreased the serum IgE level. Based on the previous report that 3 or 6 months of treatment with suplatast tosilate decreased the serum levels of IgE and IL-4 in adults with perennial allergic rhinitis (26), we assessed the changes of parameters over a 6-month period in this study. The failure of suplatast tosilate to suppress IgE production may have been related to the low age of the subjects in the suplatast group (mean age at the start of treatment with suplatast: 365.5 days), because there is a gradual increase of tolerance to food allergens such as egg white and cow's milk, while sensitization to inhaled allergens like Der P and house dust mite shows a rapid increase at this age and infants with an atopic tendency show increased IgE synthesis at this age (27). Accordingly, we were not able to assess the efficacy of suplatast from the total IgE level. The Early Treatment of the Atopic Child (ETAC) study investigated the use of cetirizine, an H1-blocker like ketotifen for preventing the onset of asthma and found no significant overall benefit compared with the placebo, although asthma was prevented in patients sensitized to house dust mite or grass pollen (10). Our patients had high antibody titers for food allergens, but their mean baseline CAP RAST scores were 2 or less for both house dust mite and Der P. This suggests that suplatast was more effective than H1-blockers for patients who were not strongly sensitized to inhaled allergens. As we did not initially plan to assess changes of specific IgE levels in the present study, these parameters were only measured in a few patients after the start of treatment. Therefore, drawing firm conclusions is impossible, but we plan to investigate further whether suplatast has a similar effect to that of immunotherapy, which prevents the development of new allergies (e.g., suppresses reactions to inhaled allergens) (28). In the present study, we directed our attention to the Th1/Th2 ratio. At birth, the production of INF-c is very low and infants are in a state where the immune response is Th2 dominant. If IFN-c production increases during the 6 months after birth, the immune response will become Th1 dominant and the production of IL-4 will be inhibited, preventing the acquisition of an atopic predisposition. In an environment that does not cause induction of IFN-c, however, its level gradually increases with maturity, but IL-4 also continues to be produced until an atopic predisposition is acquired (29). Our preliminary study showed that persons with a strong atopic predisposition, who developed food allergies followed by atopic dermatitis, asthma, and allergic rhinitis, actually had a higher Th1/Th2 ratio than healthy subjects and had a Th1-Th2 balance skewed toward Th2 dominance (unpublished observation). Such findings suggest that there is a tendency for Th2 dominance in infancy and that an increase of inflammation due to eosinophils, etc. may lead to the eventual onset of asthma. Suplatast has been shown to inhibit the activity of eosinophils by in vitro and in vivo studies, including research performed using peripheral blood, sputum, and bronchial tissue specimens obtained by biopsy (12–14, 16, 17). In the present study, suplatast significantly decreased the peripheral blood eosinophil count compared with ketotifen. There have been several reports of a relationship between the onset of asthma and eosinophils. For example, Bromchoalveolar lavage fluid (BALF) levels of Eosimophilic Catiomic Protein (ECP) are higher in patients with childhood asthma than in those with infantile wheeze (30), and persons who subsequently develop asthma have more Eosimophil Granulocyte-2 (EG2)- positive cells in the epithelium or lamina propria on bronchial biopsy than those who do not (31).

It appears that inhibition of the onset of asthma may be attributable to two factors, which are a decrease of the eosinophil count and a shift of the Th1/Th2 ratio toward Th1 dominance. The results of our study provide some corroboration for the hypothesis that inhibition of eosinophilic inflammation and improvement of the Th1/Th2 balance can contribute to preventing the onset of asthma.

Suplatast Tosilate for Prophylaxis of Pediatric Atopy 297

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The present investigation was only a pilot study, but it is still clinically significant that more than half of our patients with atopic dermatitis and food allergies developed asthma before age three during treatment with ketotifen, while only 20% of the suplatast group did so. Among the criteria in the asthma predictive index (API) (32), which is based on the Tucson Children's Respiratory Study, as well as the major and minor criteria in the modified asthma predictive index (mAPI) (33) based on the PEAK trial, a parental history of asthma, physician-diagnosed atopic dermatitis, and allergic sensitization to milk, egg, or peanuts correspond to the criteria used in the present study. These other studies have suggested that early intervention with suplatast can prevent progression to chronic asthma if patients meeting the criteria that suggest an increased likelihood of progression to chronic asthma in the future are treated before they develop wheezing. Both the API and the mAPI include the criterion of an eosinophil count ‡4%. Most of the patients in the present study met this criterion and showed a significant decrease of eosinophils after treatment with suplatast. Therefore, early intervention with suplatast may prevent progression to chronic asthma even in patients with a high eosinophil count, who have an increased risk of developing chronic asthma. The finding that a lower percentage of patients in the suplatast group needed hospital admission for asthma also serves as evidence that this drug may prevent progression to chronic asthma.
