Assessment of Steroid Hormones in Both Saliva and Blood During a Phase 2 Clinical Trial for the Use of Tildacerfont in Adults With Classic Congenital Adrenal Hyperplasia

Background: Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is an autosomal recessive disorder characterized by an inability to synthesize endogenous cortisol resulting in overproduction of 17-hydroxyprogesterone (17-OHP) and androgens such as androstenedione (A4). Serum-based methods to measure steroid hormones typically require clinic visits and are not amenable to frequent, serial measurements when patient daily glucocorticoid doses are adjusted. Reliable, non-invasive new methodologies that can easily be adopted in a clinical trial setting are needed to complement existing measures of disease control. Here we report on the correlation between salivary and serum steroid hormone data from a Phase 2 proof-of-concept study for tildacerfont, a second generation corticotropin-releasing factor-1 (CRF(1)) receptor antagonist, which previously showed an ability to reduce excess adrenocorticotropic hormone (ACTH), 17-OHP, and A4 concentrations. Methods: Subjects with CAH under evaluation for tildacerfont underwent concurrent salivary and serum concentration measurements of androstenedione (A4), 17-hydroxyprogesterone (17-OHP) and testosterone (T) at approximately 8 am every 2 weeks for up to 6 weeks. Both serum and saliva samples were measured using liquid chromatography-tandem mass spectrometry. Results: 25 subjects (16 females) with a median age of 31 years (range 19-67) participated; median body mass index (BMI) was 27.8 kg/m(2) (22-62 kg/m(2)). The number of matched samples across time points were: n=106 (17-OHP), n=106 (A4) and n=98 (T). 17-OHP and A4 were well correlated between serum and salivary assessments, r=0.80 (p<0.001) and r=0.80 (p<0.001), respectively, using kendall rank tests. T measurements had a lower correlation, r=0.67 (p<0.001). Over the duration of treatment, correlations between saliva and serum for 17-OHP and A4 were generally stable with only small differences across sex and clinic visit. Correlations between saliva and serum for T showed a moderate degree variability in women and a high degree of variability in men across visits. While correlations were high for A4 and 17-OHP, the magnitude of change, as a percentage of baseline across time points, was less pronounced with saliva as compared to serum. Conclusions: The ability to employ salivary steroid hormone measurements in CAH patients was demonstrated in a clinical trial setting. These data show that the measurement of the hormones 17-OHP and A4 in saliva may offer a promising, non-invasive approach to more frequently assessing response to therapy in patients with CAH.