Screen for Latent TB Before and During CZP Treatment

Apr 30, 2015

Analysis of data from clinical trials as TB screening protocols changed shows the value of testing for tuberculosis when treating patients for rheumatoid or psoriatic arthritis or spondyloarthropathies with certolizumab pegol.

Mariette X, Vencovsky J, Gomez-Reino J, et al., The incidence of tuberculosis in patients treated with certolizumab pegol across indications: impact of baseline skin test results, more stringent screening criteria and geographic region.RMD Open 2015;1:e000044 doi:10.1136/rmdopen-2014-000044.

The risk for tuberculosis (TB) and other infections is increased with TNF alpha (TNF-α) blockers, but a multi-national study shows that stricter TB screening appears to substantially reduce that risk among patients treated with the TNF-α blocker certolizumab pegol (CZP).

The risk was reduced even when patients with TB were treated with isoniazid (INH) after starting CZP.

TB onset soon after starting anti-TNF-α drugs indicates a probable reactivation of latent TB infection (LTBI), while TB arising after months of  continuous exposure to TNF-α blockers is more likely due to a new infection, the study authors note.

In their study, they examined TB incidence during trials of long-term CZP for rheumatoid arthritis (RA), psoriasis, psoriatic arthritis (PsA), and axial spondyloarthritis (axSpA), before and after stricter screening protocols for TB.

Analyzing data for 5,402 CZP patients with RA, PsA, and axSPA in clinical trials, the researchers find an overall TB incidence rate (IR) of 0.42 per 100 patient years (PY).

In separate pooled safety data for 4,049 RA clinical trial patients, the overall IR for TB was 0.47/100 PY.

Data were stratified according to whether a clinical trial was completed before screening protocols (original trials), initiated after amended protocols with a lower purified protein derivative (PPD) tuberculin skin test cut-off of 5 mm-20 mm (intermediate period trials), and after strict screening-treatment protocols were enacted in 2007 (current trials).

The 2007 CZP trial protocols mandate that any patient with a positive TB test – a PPD induration at or above 5 mm -- should begin 9 months of INH treatment for latent TB.

In original clinical trials of CZP for RA, the IR for TB was 2.63/100 PY. In intermediate period RA trials, the IR was 0.30/100 PY and for current trials the IR was 0.18/100 PY, a significant reduction.

In terms of length of CZP exposure, of the 44 confirmed TB cases in RA patients, 21 were reported during the first year (including 2 cases in current trials). Most of the TB cases occurred in Central and Eastern Europe, where TB is endemic.

Of the 46 cases of confirmed TB across all of the CZP trials (44 in RA, 1 in psoriasis, and 1 in axSpA), 34 were seen prior to the implementation of stricter screening rules (33 in RA, 1 in psoriasis) and predominantly occurred in patients who did not receive INH treatment.

Physicians should be aware of the importance of adequate TB screening for patients on biological therapy where TB is endemic but also in countries with relatively low TB rates, the authors say.

Increasing TB screening stringency “may reduce TB incidence in patients treated with anti-TNF (drugs) and enable those receiving treatment for LTBI to continue biological therapy for their chronic autoimmune disease,” the study concludes.