Loss-of-response and adverse events (AE) to biologics have been linked to HLA-DQA1*05 allele. However, the clinical factors or biologic used may influence treatment duration. Our objective was to evaluate the influence of clinical and therapeutic factors, along with HLA, in biological treatment discontinuation.
A retrospective study of consecutive IBD patients treated with biologics between 2007 and 2011 was performed. Main outcome was treatment discontinuation due to primary non-response (PNR), secondary loss of response (SLR) or AE. HLA-DQA1 genotyping was done in all patients. Regression analyses were used to assess risk factors of treatment discontinuation.
One hundred fifty patients (61% male) with 312 biologic treatments were included. 147 (47%) were discontinued with a cumulative probability of 30%, 41% and 56% at 1, 2 and 5 years. The use of infliximab (p=0.006) and articular manifestations (p<0.05) were associated with treatment discontinuation. Considering cause of withdrawal, Ulcerative Colitis (UC) had a higher proportion of PNR (HR=4.99; 95% CI=1.71-14.63; p=0.003), SLR was higher if biologics had been indicated due to disease flare (HR=2.32; 95% CI=1.05-5.09; p=0.037) while AE were greater with infliximab (HR=2.46; 95% CI=1.48-4.08; p<0.001) or spondylitis (HR=2.46; 95% CI=1.78-6.89; p<0.001). According to the biological drug, HLA-DQA1*05 with adalimumab showed more SLR in cases with Crohn's disease (HR=3.49; 95% CI=1.39-8,78; p=0.008) or without concomitant immunomodulator (HR=2.8; 95% CI=1.1-6.93; p=0.026).
HLA-DQ A1*05 was relevant in SLR of IBD patients treated with adalimumab without immunosupression. In patients treated with other biologics, clinical factors were more important for treatment interruption, mainly extensive UC or extraintestinal manifestations and having indicated the biologic for flare.