Background: Everolimus-related interstitial lung disease (ILD) (also: pneumonitis) poses a difficulty for physicians, as it is hard to discriminate ILD from other causes of respiratory symptoms and to decide on safe treatment continuation.
Objective: We investigated the capability of pulmonary function tests (PFT), plasma biomarkers, everolimus pharmacokinetics, and FDG-PET to discriminate between everolimus-related ILD and other causes of respiratory problems and to predict the severity of ILD.
Patients and methods: Women starting treatment with everolimus plus exemestane for advanced breast cancer were included. At baseline and during the first 3 months, respiratory symptoms, PFT with diffusion capacity of the lungs for carbon monoxide corrected for hemoglobin (DLCOc) and forced vital capacity, serum plasma biomarkers (including SP-D and YKL-40), everolimus trough concentration, and 18F-FDG-PET were prospectively recorded.
Results: Twenty-seven (out of 29 included) patients were evaluable for analysis. Fifteen patients (56%) developed everolimus-related respiratory signs or symptoms and four patients (15%) needed everolimus discontinuation and received corticosteroids. Change in DLCOc differentiated ILD from alternative diagnoses with 0.91 sensitivity and 0.78 specificity. Decrease in DLCOc (non-significant) was greatest in patients who needed everolimus discontinuation. Serum SP-D and YKL-40 could differentiate ILD from alternative diagnoses with 0.83 and 0.83 sensitivity, and 0.85 and 0.62 specificity, respectively. 18F-FDG-PET abnormalities did not precede clinical symptoms. No relationship between ILD and everolimus trough concentration was found.
Conclusions: This study shows that everolimus-related ILD occurs frequently. Prospective monitoring of DLCOc in combination with measurement of serum SP-D and YKL-40 appear useful to discriminate ILD from other causes of respiratory symptoms. Clinicaltrials.gov identifier: NCT01978171.