P1070 Utilization of HLA-DQA1*05 haplotype testing in routine clinical practice to stratify advanced therapies: A prospective pilot study

Abstract

Abstract Background A potential association between HLA-DQA1*05 allele and development of anti-drug antibodies in Anti-TNF treated Crohn’s Disease patients is reported in the PANTS study. The utility of stratifying treatment based on the HLA-DQA1*05 status has not been evaluated in a biomarker stratified clinical trial and there are no prospective studies evaluating the impact of using HLADQA1*05 in routine clinical practice to decide on monotherapy versus combo therapy while initiating on anti-TNFs. We aimed to determine the impact of carriage of HLADQA1*05 allele to guide the need for concomitant immunomodulators in IBD patients planned for Infliximab therapy. Methods In our prospective study, 97 adult IBD patients were included. All patients were screened for HLADQ2 haplotype as part of their routine pre-biologic screen. Stratification was done according to the presence of HLA-DQA1*05 haplotype. HLADQA1*05 positive patients were assigned combo therapy with Infliximab combined with either methotrexate or azathioprine. HLADQA1*05 negative patients were given infliximab monotherapy unless another indication for concomitant immunomodulation was present. Patients were followed for a minimum of one year after drug initiation. Primary outcome was drug persistence, expressed as time to discontinuation of infliximab, segregated by the treatment decision based on HLA-DQA1*05 status. Secondary outcomes were proportion of patients developing anti-drug antibodies and time to antibody development. Statistical analysis was done using Kaplan-Meier curves and log-rank test. Results Baseline characteristics are detailed in Table 1. HLA-DQA1*05 was positive in 41/97(42%) of patients and combo therapy was offered to 33/41(80%) of those patients. Immunomodulators were avoided in 39/97(40.2%) patients representing the subset of patients with negative HLADQA*105 to whom no immunomodulator was offered. There was no statistically significant difference in drug persistence rates between the groups treated based on HLA-DQA*105 status. 54/97(55.6%) of the patients developed anti-infliximab antibodies during their follow-up (25/41(60.9 %) in HLA positive and 29/56 (51.7%) in HLA negative). Neutralizing drug antibodies with absent drug levels were detected in 15/97(15.5%) of patients (8/41(19.5%) in HLA positive, 7/56(12.5%) in HLA negative). The median time to antibody development was 33.5 weeks (IQR 22-46.7). Conclusion This is the first prospective study suggesting HLA-DQA1*05 haplotype testing can be used in routine clinical practice to stratify therapy based on the need for immunomodulators in infliximab treated IBD patients. HLA-DQA1*05 negative patients may be started on monotherapy with potential for improving safety and reducing costs of immunomodulator monitoring.