STUDY DESIGN AND END POINTS

The study was designed by the investigators, approved by the data and safety monitoring board at the National Center for Research Resources and the institutional review board at each participating site, and conducted within the National Institutes of Health Rare Lung Diseases Consortium. The LAM Foundation assisted with recruitment of patients and with study logistics. The data, collected with the use of Internet-based electronic case-report forms, were reported to the data management and coordinating center, where they were securely held and analyzed. All the authors participated in the writing of the first and subsequent drafts of the manuscript and in the decision to submit the manuscript for publication and vouch for the completeness and veracity of the data and data analyses. Pfizer provided the drug and the money for the costs of study visits but had no role in the design or conduct of the study or the analysis or reporting of the data. The protocol, including the statistical analysis plan, is available at NEJM.org.

The study design included a screening visit and a 12-month, double-blind, placebo-controlled treatment period, followed by a 12-month observation period during which no patients received a study drug and all patients remained unaware of their treatment assignment. Patients who met the eligibility criteria were randomly assigned by the data management and coordinating center, in a 1:1 ratio, to receive oral sirolimus, at an initial dose of 2 mg per day, or matched placebo. Sirolimus levels were measured at each follow-up visit; the results of these measurements were revealed only to an independent medical monitor, who made dosing recommendations to maintain sirolimus trough levels between 5 and 15 ng per milliliter, as well as corresponding sham dose adjustments in the placebo group.

The primary outcome measure was the FEV₁ response, which was assessed as the rate of change in FEV₁ (FEV₁ slope) in milliliters per month. Secondary outcome measures included responses in forced vital capacity (FVC), measured as changes from baseline to 12 months; lung volumes (residual volume, functional residual capacity, and total lung capacity); the distance covered on a 6-minute walk test; diffusing capacity of the lung for carbon monoxide; serum VEGF-D levels; and scores on the St. George’s Respiratory Questionnaire, the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), the Functional Performance Inventory, the General Well-Being Questionnaire, and the EuroQOL visual-analogue scales assessing fatigue, dyspnea, and quality of life. Study visits occurred at baseline, at 3 weeks, and at 3, 6, 9, 12, 18, and 24 months. Primary and secondary end points were measured at baseline and at every visit after the 3-week visit, as described in the study calendar in the Supplementary Appendix.

Adverse events were assessed according to the Common Terminology Criteria for Adverse Events (version 3.0). Laboratory testing to assess safety included hematologic, serum chemical, and urine chemical tests.

SERUM LEVELS OF SIROLIMUS AND ADHERENCE TO MEDICATION

The serum levels of sirolimus in the placebo group were below the detection limit throughout the study. Other than brief out-of-range excursions, the sirolimus levels in the active-treatment group were maintained between 5 and 15 ng per milliliter, except in the case of four patients in whom levels were intentionally kept below therapeutic levels for 3 months or more in order to control side effects.

PRIMARY ANALYSIS

In the placebo group, the FEV₁ slope from baseline to 12 months was −12±2 ml per month; the slope was significantly less than zero (P<0.001), a finding that was consistent with declining lung function (Table 2). The FEV₁ slope in the sirolimus group was 1±2 ml per month, which was not significantly different from zero; this was indicative of the stabilization of lung function during treatment (Fig. 2A). There was a significant difference between the two groups in the FEV₁ slope (P<0.001). The absolute difference in the mean change in FEV₁ during the treatment period, calculated as the difference between the mean change in the placebo group (−134±182 ml) and the mean change in the sirolimus group (19±124 ml), was 153 ml (P<0.001 for the between-group difference) (Fig. 2B). A total of 12% of the patients in the placebo group, as compared with 46% of the patients in the sirolimus group, had FEV₁ values at or above baseline values at the 12-month visit (P<0.001) (Fig. 2C).

Open in a separate window

Figure 2

Change in Lung Function during the Treatmentand Observation Phases of the Trial

Panel A shows the mean forced expiratory volume in 1 second (FEV₁) at baseline and at each follow-up visit in the placebo and sirolimus groups. The number of patients for whom FEV₁ data were available at each time point is also shown. Panel B shows the mean changes from baseline to 12 months in FEV₁ and forced vital capacity (FVC) in the 34 patients in the placebo group and the 41 patients in the sirolimus group for whom 12-month data were available. Panel C shows the frequency of FEV₁ changes, in increments or decrements of 5% of the baseline value, from baseline to 12 months. The percentage of patients who had any improvement in FEV₁ was significantly greater in the sirolimus group than in the placebo group (46% vs. 12%, P<0.001). Conversely, a significantly greater percentage of patients in the placebo group than in the sirolimus group had some worsening of FEV₁ (67% vs. 44%). In Panels A and B, T bars indicate standard errors.

Table 2

Effects of Sirolimus on Primary and Selected Secondary Outcome Variables during the Treatment Period.^*

Variable	Value at 12 Months		Change from Baseline			Rate of Change per Month
	Placebo (N = 34)	Sirolimus (N = 41)	Placebo (N = 34)	Sirolimus (N = 41)	P Value†	Placebo (N = 43)	Sirolimus (N = 46)	P Value‡
Pulmonary function
FEV1 (ml)	1272±414	1383±394	−134±182§	19±124	<0.001	−12±2¶	1±2	<0.001
FVC (ml)	2843±668	2780±735	−129±233§	97±260	0.001	−11±3¶	8±3¶	<0.001
Total lung capacity (ml)	5464±1217	4944±982	−7±650	94±504	0.65	−2±7	8±7	0.34
Residual volume (ml)	2502±969	2112±617	−16 ±514	38±538	0.61	−3±7	4±7	0.46
Functional residual capacity (ml)	3260±968	2912±660	−123±521	53±335	0.43	−11±6	6±6	0.049
DLCO (ml/mm Hg/min)	9.61±4.06	9.62±3.92	−0.62±2.89§	−0.06±1.50	0.38	−0.06±0.03¶	−0.01±0.02	0.17
6-Minute walk distance (m)	418±107	431±104	26±51§	24±59§	0.99	1.47±0.87	1.65±0.81¶	0.88
Score on EuroQOL visual-analogue scale for quality of life||	65.60±18.47**	73.71±18.03	−2.34±15.77	6.10±16.96	0.02	−0.21±0.20	0.39±0.19¶	0.03
Total score on Functional Performance Inventory††	2.33±0.47	2.35±0.49	−0.05±0.24	0.10±0.38	0.08	−0.009±0.004¶	0.005±0.004	0.03
Serum VEGF-D (pg/ml)	2444±3862**	862±540	−14.81±1113	−1032±1301§	0.001	−2.42±17.23	−88.01±16.61¶	0.001

Open in a separate window

^*Plus–minus values are means ±SD. DL_CO denotes diffusing capacity for carbon monoxide, FEV₁ forced expiratory volume in 1 second, FVC forced vital capacity, and VEGF-D vascular endothelial growth factor D.

^†Two-sided P values for the comparison between the placebo and sirolimus groups of the mean change from baseline were calculated with the use of a general linear model, with adjustment for baseline levels of variables.

^‡Two-sided P values for the comparison between the placebo and sirolimus groups of the rate of change per month were calculated with the use of a linear mixed-effects model.

^§The two-sided P value for the change from baseline within the placebo or sirolimus group, as calculated with the use of the Wilcoxon signed-rank test, was less than 0.05 for FVC and 6-minute walk distance, less than 0.01 for DL_CO, and less than 0.001 for FEV₁ and VEGF-D level.

^¶The two-sided P value for the rate of change per month within the placebo or sirolimus group, as calculated with the use of a linear mixed-effects model, was less than 0.05 for the total score of the Functional Performance Inventory, the DL_CO, and the EuroQOL visual-analogue scale, less than 0.01 for the FVC, and less than 0.001 for VEGF-D level and FEV₁.

^||The EuroQOL visual-analogue scale measures self-reported ratings of health status. Scores range from 0 to 100, with lower scores indicating worse functioning.

^**The two-sided P value for the difference between the placebo and sirolimus groups at 12 months was less than 0.05, as calculated with the use of the Wilcoxon rank-sum test.

^††Scores on the Functional Performance Inventory range from 1 to 4, with lower scores indicating lower health status.

SECONDARY ANALYSES

The FVC slope during the treatment phase was −11±3 ml per month in the placebo group, as compared with 8±3 ml per month in the sirolimus group (P<0.001) (Table 2). The FVC slope was significantly less than zero in the placebo group (P = 0.001), which was consistent with a decline in lung function, and the slope was significantly greater than zero in the sirolimus group (P = 0.009), which was consistent with an improvement in lung function during treatment. The absolute difference in the mean change in FVC during the treatment phase, calculated as the difference between the mean change in the placebo group (–129±233 ml) and the mean change in the sirolimus group (97±260 ml), was 226 ml (P = 0.001 for the between-group difference) (Fig. 2B). A total of 23% of the patients in the placebo group, as compared with 54% of patients in the sirolimus group, had FVC values that were at or above baseline values at the 12-month visit (P<0.001). The between-group difference in the slope for functional residual capacity during the treatment phase was also significant (P = 0.049), but the differences in the slopes for total lung capacity, residual volume, diffusing capacity for carbon monoxide, and distance covered on a 6-minute walk test were not significant (Table 2).

There were significant differences favoring sirolimus in the change from baseline to 12 months in the score on the EuroQOL visual-analogue scale for quality of life and in the total score on the Functional Performance Inventory. The changes in other measures of health-related symptoms did not differ significantly between the two groups (Table 2). Mean VEGF-D levels were similar in the two groups at baseline but were significantly lower in the sirolimus group than in the placebo group at 6 and 12 months (Tables 1 and ​and22).

ANALYSES OF DATA FROM THE OBSERVATION YEAR

FEV₁ declined in both groups during the observation year (a decline of 8±2 ml per month in the placebo group and of 14±3 ml per month in the sirolimus group) (Fig. 2A). Although these slopes were both less than zero (P = 0.005 and P<0.001, respectively), the difference between them did not reach significance (P = 0.08). The mean change in FEV₁ from baseline to 24 months did not differ significantly between the two groups (−180±100 ml in the placebo group and −150±170 ml in the sirolimus group). Similarly, with respect to FVC, there were no significant between-group differences in the observation-year slopes or the mean changes from baseline to 24 months. The mean serum VEGF-D levels at 24 months remained elevated in the placebo group (2107±2146 pg per milliliter in the 13 patients for whom data were available at 24 months) and depressed in the sirolimus group (930±461 pg per milliliter in the 14 patients for whom data were available at 24 months). There were no significant differences in the slopes from 12 to 24 months or in the mean change from baseline to 24 months in any other variables measured, including lung volumes, diffusing capacity for carbon monoxide, distance covered on a 6-minute walk test, and symptoms.

Supported by grants from the NIH Office of Rare Disease Research, administered by the National Center for Research Resources (RR019498, to Drs. Trapnell and McCormack; and RR019259, to Drs. Lee and Krischer), the Food and Drug Administration (FD003362, to Dr. McCormack), Canadian Institutes of Health Research (to Drs. Downey, Cohen, and Singer), Pfizer (formerly Wyeth) Pharmaceuticals (to Dr. McCormack), the Japanese Ministry of Health, Labor, and Welfare (H 19 Rinshoshiken 008, to Drs. Nakata and Inoue), the LAM Foundation (to Dr. McCormack), the Tuberous Sclerosis Alliance (Rothberg Courage Award, to Dr. McCormack), Cincinnati Children’s Hospital Medical Center (Institutional Clinical and Translational Science Award 1UL1RR026314 01, to Drs. Young and McCormack, and Translational Research Initiative Award, to Drs. McCormack and Trapnell), Vi and John Adler, and the Adler Foundation. Drs. Moss and Taveira-DaSilva were supported by the Division of Intramural Research, National Heart, Lung, and Blood Institute. Pfizer provided the study drug and money for study visit costs.

We thank John Bissler, M.D., for his assistance in providing the Cine MRI of a woman with tuberous sclerosis and lymphangioleiomyomatosis.