A pilot study of zafirlukast as an anti-inflammatory agent in the treatment of adults with cystic fibrosis

1. Introduction 

Leukotrienes (LTs) are formed from activated inflammatory cells. These proinflammatory chemical mediators recruit other inflammatory cells to lung tissue and in the airways stimulate mucus hypersecretion, oedema and bronchospasm [1]. The C4, D4, and E4 LTs, referred to as the cysteinyl-LTs as each has a thio-ether linked peptide, all use the CysLT1 airway receptor site. Zafirlukast acts as a LT receptor antagonist, interrupting the inflammatory cascade by preventing the cysteinyl-LTs activating the receptor. Randomised, double-blind, placebo-controlled trials have shown significant improvements in asthma symptoms and lung function following treatment with zafirlukast 20 mg twice daily [2], [3].

The important negative effect of uncontrolled inflammation on lung function in cystic fibrosis (CF) is well documented [4], [5]. The pathogenic potential of LTs in CF has been suggested by several studies. Sampson et al. [6] showed that children with CF had greater urinary LTE4 levels than controls. Urine levels correlated significantly with sputum LTE4 levels and with the total cysteinyl-LT content in sputum. High levels of both LTE4 and LTB4 were found in sputum. Spencer et al. [7] documented high sputum cysteinyl-LT levels, which correlated with the overall severity of the pulmonary disease in children. Greally et al. [8] showed a significant positive correlation between TNF-alpha and both LTB4 and total cysteinyl-LT sputum content. Respiratory function was inversely related to TNF-alpha concentrations, suggesting that both LTs and TNF-alpha may be involved in airway inflammation and obstruction in CF. These studies suggest a role for LTs in the pathophysiology of CF.

There are only two studies on the use of LT receptor antagonists in CF. Morice et al. [9] gave montelukast to 11 stable but otherwise unselected patients with CF for 2 weeks in an open label trial. Patients documented subjective improvement and better exercise tolerance. Schmitt-Grohe et al. [10] gave montelukast or placebo to 16 patients with CF for 21 days each in a cross-over study. They found a significant reduction in serum eosinophilic cationic protein and in eosinophils, suggesting that blocking of the LT receptor might reduce eosinophilic inflammation.

The aim of this study was to see if the anti-inflammatory effects of zafirlukast resulted in improvements in lung function and clinical wellbeing in adult patients with CF who had no evidence of bronchial hyper-reactivity or allergic bronchopulmonary aspergillosis (ABPA).

2. Patients and methods 

Clinically stable patients were invited to participate in the study. Exclusion criteria were any of the following; history of recent ABPA or asthma, bronchodilator reversibility >15%, raised peripheral blood eosinophil count, serum IgE>200 IU, or positive aspergillus RAST or precipitin test results. Patients were randomised to receive zafirlukast 20 mg twice daily plus all routine treatments for 4 months followed by routine treatment alone for 4 months, or vice versa, in an open-label cross-over trial. A washout period was not introduced between the two arms of the study as only data from the end of each treatment period were analysed, except for days of additional antibiotic therapy (a secondary outcome variable).

Patients received the following concomitant respiratory directed therapies; nebulised antibiotics 55%, bronchodilators 93%, oral corticosteroids 21%, inhaled corticosteroids 66%, pulmozyme 52%.

Outcome measures were recorded at baseline and at 2 monthly intervals to 8 months. These included respiratory function tests (RFTs), weight, and peripheral blood inflammatory markers (c reactive protein, white cell count, IgG, plasma viscosity). Four clinical scores were completed, modified from Ranasinha et al. [11] Dyspnoea was represented by a 100 mm vertical line ranging from no shortness of breath at the bottom to severe shortness of breath at the top [12]. Patients scored the line according to perceived dyspnoea experienced. Answers to questions on general well being (feeling, energy, physical activity, appetite and sleep pattern) and on CF related symptoms (ease of sputum expectoration, cough frequency and severity, congestion, wheeze) were ranked on a 5-point Likert scale in which one represented the worst symptoms and five represented no symptoms. Finally a modified NIH score (details available on request) was used to assess overall clinical status [13] at 0, 4 and 8 months. At each visit patients were asked to report the number of days on which additional oral or intravenous antibiotics had been prescribed.

Primary outcome measures were changes in RFTs, absolute values and percent predicted, and the modified NIH clinical score. The data were analysed according to the methods of Hills and Armitage for cross-over studies [14]. T-tests were applied to test for treatment by period interactions, period effects and treatment effects. For all variables except days of additional antibiotic therapy the data recorded at 4 and 8 months were used in the analysis as the assessments of response in the first and second treatment periods respectively. For days of added intravenous and oral antibiotic therapy, responses during the first and second periods were denoted respectively, by the sum of the data recorded at 2 and 4 months, and at 6 and 8 months. In all tests a P-value <0.05 denoted statistical significance.

3. Results 

Thirty patients, (15 male), were entered into the study. Mean patient age was 24 years (range 20–32 years). Due to the cross-over design all patients were required to have had at least one assessment of efficacy for both treatment periods to be eligible for analysis. Consequently five patients (two receiving zafirlukast in the first period) were excluded as they withdrew before the start of the second treatment period. The withdrawals were not related to any adverse event or drug side effect. Eleven of the remaining 25 received zafirlukast in the first treatment period.

The baseline data are summarised in Table 1, Table 2. Mean responses for primary outcome variables are shown in Fig. 1. Mean responses and treatment effects for secondary outcome variables are shown in Table 3. There was no evidence of a significant treatment by period interaction for any variable and therefore the cross-over methods could be applied to all variables.

Table 1. Mean values (S.D.) of baseline assessments for primary outcome variables

		Number	FEV1(l)	FEV1	FVC(l)	FVC	FEF25–75(l)	FEF25–75	Modified
				(%pred)		(%pred)		(%pred)	NIH score
									(0–50)
	Group 1	11	2.25	59	3.3	75.5	1.47	31.1	20.5
	Zafirlukast		(1.03)	(20.8)	(1.2)	(20.6)	(0.99)	(18.8)	(7.4)
	Period 1
	Group 2	14	2.45	64.4	3.54	79.9	1.99	43.9	18.8
	Zafirlukast		(1.01)	(24.4)	(0.93)	(19.4)	(1.87)	(38.6)	(6.7)
	Period 2

Table 2. Mean values (S.D.) of baseline assessment for secondary outcome variables

		Number	Weight	Crp	Plasma	White	IgG	Dyspnoea	General	CF symptom
			(kg)	(mg/l)	viscosity	cell count	(g/l)	score	wellbeing score	score
					(cP)	(×109/l)		(mm)	(0–25)	(0–25)
	Group 1	11	60	12.6	1.81	12.1	14.8	23.4	20	17.5
	Zafirlukast		(10.5)	(6.6)	(0.09)	(4.9)	(3.7)	(16.5)	(4.3)	(3.4)
	Period 1
	Group 2	14	60.8	14.3	1.8	10.2	13.9	13.8	22.6	20.5
	Zafirlukast		(8.9)	(14.8)	(0.19)	(2.9)	(3.4)	(13.1)	(3)	(2.1)
	Period 2

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Fig. 1. Mean responses (S.E.) in each treatment arm for primary outcome variables.

Table 3. Mean responses (S.D.) and treatment effects in each treatment arm for secondary outcome variables

		Number	Wt.	Intra-venous	Oral	CRP	Plasma	White cell	IgG	Dyspnoe	General well-	CF
			(kg)	anti-biotics	anti-biotics	(mg/l)	viscosity	count	(g/l)	score	being score	symptom score
				(days)	(days)		(cP)	(×109/l)		(mm)	(0–25)	(0–25)
	Mean responses
	Zafirlukast	25	60.8	12.8	6.9	14.4	1.78	10.5	13.8	18.8	21.6	19.3
			(9.5)	(12.9)	(8.9)	(16.8)	(0.14)	(4.2)	(3.6)	(19.5)	(2.8)	(3.2)
	No treatment	25	61	12.4	5	15.4	1.81	9.5	14.3	25.3	20.6	17.9
			(9.6)	(15.1)	(8.3)	(15.8)	(0.16)	(3.4)	(3.3)	(24.8)	(4.4)	(4.1)
	Treatment effect
	Effect size		0.14	−0.19	1.27	−2.01	−0.03	0.73	–	−6.62	0.99	1.32
									0.55
	95% CI		0.9	−6.44	−2.08	−9.74	−0.08	−1.21	–	−14.9	−0.98	−0.43
			0.62	6.07	4.61	5.71	0.02	2.66	−1.17	1.67	2.95
									0.07
	P value		0.69	0.95	0.4	0.6	0.26	0.44	0.08	0.11	0.3	0.13

With respect to the primary variables, the modified NIH score was significantly lower on zafirlukast compared to routine treatment, (estimated treatment effect −1.57, P<0.05). Both absolute and percent predicted values for FEV1 and FVC were non-significantly higher on zafirlukast, (effect size 0.04 l, 0.81% and 0.04 l, 0.91%, respectively). FEF25–75% values showed a significant period effect (P=0.01) and tended to be higher in the first treatment period irrespective of which treatment the patient was receiving. Consequently the estimates of the treatment effects for FEF25–75% are not reliable as it is impossible to separate out the true treatment effect from the period effect.

With respect to the secondary outcome measures there was no evidence of a significant difference between zafirlukast and routine treatment for any of the variables. Significant period effects were apparent for c-reactive protein (P=0.04) and total peripheral blood white cell count (P=0.02), with both variables tending to be lower in period one. The treatment effects associated with them should therefore be interpreted with caution.

No adverse events were reported.

4. Discussion 

In adult patients with CF, who were selected to minimise any benefits that might be derived from its efficacy as an asthma drug, the addition of the LT receptor antagonist zafirlukast to routine treatment regimens significantly improved patients’ clinical status as measured by a modified NIH score. There were non-significant improvements in respiratory function, plasma viscosity, IgG levels, dyspnoea, wellbeing and CF symptom scores, and fewer days of intravenous therapy. Twenty-five patients completed the trial and greater differences between treatment with and without zafirlukast may be evident in a larger multicentre study.

Morice et al. [9] attributed the efficacy of a LT receptor antagonist in CF to a blockage of the effects of Aspergillus stimulated Th2 inflammation and LT synthesis. In our study we excluded patients with evidence of immunological reactivity to Aspergillus infection as well as those with significant bronchial reversibility. We suggest that any benefit from the LT receptor antagonists in clinically stable patients with CF is a reflection of their interference with the persistent lower respiratory tract inflammation that characterises this disease. This hypothesis is supported by Schmitt-Grohe et al. who presented data at the 24th European CF Conference 2001 which showed a montelukast induced fall in eosinophilic inflammation [10].

LTB4 may be important in mediating neutrophil influx and activation, hence encouraging the neutrophil dominated inflammation in the CF lung [15], [16]. Zafirlukast does not block the LTB4 receptor. Treatment that interferes with the action of LTB4 as well as the cysteinyl-LTs, for example 5-lipoxygenase inhibitors that block LT production from eicosanoids, might further benefit patients.

Our data suggest that treatment with zafirlukast may benefit patients when they are assessed by a clinical score which includes chest radiograph appearance, physical examination, presence or not of haemoptysis, sputum characteristics, and general health measures such as appetite, energy, exercise tolerance and dyspnoea. Plasma viscosity, serum IgG, and a dyspnoea score were also lower with treatment, and respiratory function, general well-being and CF symptom scores better. When receiving zafirlukast patients needed less days of intravenous antibiotic therapy. However, the differences between treatments only reached statistical significance for the modified NIH clinical score.

In conclusion, we have shown that the LT receptor antagonist, zafirlukast, results in a measurable clinical improvement in adult patients with CF and appears to be well tolerated. We suggest that there is now sufficient data to warrant evaluation of the role of LT antagonists in CF in an adequately powered clinical trial.