Rates of change in FEV and as potential indicators for mTOR inhibitor therapy in premenopausal lymphangioleiomyomatosis patients.

The value of rates of change in forced expiratory volume in 1 s (FEV) and diffusing capacity of the lung for carbon monoxide () to predict disease progression, and initiation of mTOR (mechanistic target of rapamycin) inhibitor therapy has not been evaluated.In 84 premenopausal lymphangioleiomyomatosis patients, individual rates of change in FEV and and their 95% confidence intervals were used to derive subsequent lowest values of FEV and that would prompt initiation of sirolimus therapy. These treatment criteria were compared with a criterion based on FEV or ≤70% predicted. In 12 patients undergoing sirolimus therapy both methods for determining the optimal point for initiation of therapy were evaluated.27 and 35 patients who experienced greater than expected rates of change in FEV and , respectively, would have been excluded from therapy based on an FEV or >70% pred. 25 of the 84 patients were eventually treated, but only when FEV or were ≤70% pred. Applying such treatment criteria to 12 patients undergoing sirolimus therapy would have delayed treatment for many years.Premenopausal females in whom FEV or are declining at rates above the expected based on their individual rates of decline, should be considered for sirolimus therapy before the FEV or falls to ≤70% pred.