Association between infliximab concentrations and clinical response in psoriasis: a prospective cohort study.

BACKGROUND: Infliximab (IFX) trough concentrations (Cmin) have been linked to treatment efficacy in psoriatic patients. Inter-individual IFX Cmin variability and factors influencing IFX pharmacokinetics could explain differences in treatment response. OBJECTIVE: To evaluate the association between IFX Cmin and clinical outcomes in psoriatic patients. METHODS: Prospective study of 33 patients with moderate to severe psoriasis receiving IFX at Bellvitge University Hospital, between October 2013 and November 2016. IFX Cmin and antibodies toward infliximab (ATI) were measured. RESULTS: We collected 155 IFX Cmin and ATI values (mean age, 46 (14) years; 11 (33.3%) women). Mean IFX Cmin was 2.5 (2.4) mg/L and ATIs were detected in six patients, resulting in undetectable IFX Cmin. IFX Cmin was significantly associated with ATI and body mass index (BMI) (ß -2.51, 95% CI -3.56 to -1.4 and ß -0.05, 95% CI -0.09 to -0.01). PASI score and PASI 90/100 response were significantly associated with IFX Cmin (IRR 0.80, 95% CI 0.70 to 0.92; OR 1.79, 95% CI 1.18 to 2.71 and OR 1.79, 95% CI 1.14 to 2.81). CONCLUSION: IFX Cmin significantly influences PASI 90/100 response rates. IFX Cmin wa significantly associated with ATI and BMI. The observed inter-individual variability in IFX Cmin supports the need for IFX drug monitoring.

Detection of interleukin-2 is not useful for distinguishing between latent and active tuberculosis in clinical practice: a prospective cohort study.

OBJECTIVE: Previous reports have identified interleukin-2 (IL-2), quantified in the supernatants of QuantiFERON®-TB Gold In-tube (QFT) after 72 h of incubation, as a potential biomarker for distinguishing between latent and active tuberculosis (TB). However, its validity has not been tested in an appropriate clinical cohort. METHODS: A multicentre study of 161 consecutive adult patients undergoing evaluation for active TB at eight TB Units in Spain. Interferon-γ (IFN-γ) and IL-2 were assessed in the supernatant of QFT after 16-24 h and 72 h of incubation. The accuracy of IL-2 for indicating latent TB infection (LTBI) was assessed by receiving operating characteristic curves. . RESULTS: Twenty-eight participants were not infected, 43 had LTBI, 69 had TB, and 21 were not classifiable. Median (interquartile range) IL-2 concentrations after 72 h of incubation were 0.0 pg/mL (0.0-0.0) in uninfected individuals, 261.0 pg/mL (81.0-853.0) in LTBI individuals, 166.5 pg/mL (33.5-551.5) in patients with extrapulmonary TB, 95.0 pg/mL (26.0-283.0) in patients with smear-negative pulmonary TB, and 38.5 pg/mL (7.5-178.0) in patients with smear-positive pulmonary TB (p <0.0001). The area under the curve of the receiving operating characteristic curve (95% CI) of IL-2 after 72 h of incubation for the diagnosis of LTBI was 0.63 (0.53-0.74) when all TB cases were considered as a single group, ranging from 0.59 (0.47-0.71) to 0.72 (0.58-0.85) when only extrapulmonary and smear-positive pulmonary TB cases respectively were considered. CONCLUSIONS: Quantification of IL-2 in the supernatant of QFT after a prolonged incubation is not useful to distinguish between LTBI and active disease in clinical practice.