The presence of antibodies to infliximab in patients is determined by an enzyme linked immunosorbent assay (ELISA). However, the detection of antibodies to infliximab can be hindered by the presence of inflixi-mab in the serum. Thus, since infliximab can remain in the circulation for at least 4-12 weeks after infusion, serum samples are usually collected for analysis 12 weeks or later after the last infusion.
When the formation of antibodies against infliximab (HACA) was determined 12 weeks after the last infusion in RA patients, HACA were detected in about 17 % of all treated patients. The rate of HACA responses was inversely proportional to the dosage; HACA formation occurred in 53%, 21% and 7% of patients treated with 1, 3 and 10 mg/kg infliximab, respectively. Concomitant treatment with methotrexate decreased the rate to 15%, 7% and 3% for the three respective dosages. The smaller proportion of patients on higher doses of infliximab who are developing HACA suggest that anti-TNF-a treatment induces a phenomenon resembling tolerance (Maini et al. 1998).
A significantly higher incidence of antibodies to infliximab was detected in Crohn's patients who received episodic treatment, i.e., they received one dose of infliximab at the beginning of the trial, but then only placebo until week 14 or later until the disease worsened. While 30% of patients on this treatment schedule developed HACA, only 8% of patients who received infliximab infusions every 8 weeks developed HACA. In addition, the incidence of HACA was higher in patients who did not receive immunomodulators compared to those who did (18% vs 10%, p = 0.02) (Hanauer et al. 2004).
This suggests that higher doses of infliximab at scheduled (every 8 weeks) infusions and perhaps in combination with an immunomodulator are the best treatment paradigm to reduce the possibility of developing HACA.
Was this article helpful?
Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.