Intra-patient variability in adalimumab drug levels within and between cycles in Crohn's disease

BACKGROUND

Whether therapeutic drug monitoring for adalimumab needs to be performed at trough has not been defined.

AIM

To determine intra-patient adalimumab drug-level variation and to identify modulating patient and disease factors.

METHODS

In this prospective observational study, adult patients with Crohn's disease established on maintenance adalimumab had drug levels measured repeatedly according to pre-defined schedules (visit 1: day 4-6, visit 2: day 7-9, trough: day 13-14) across two consecutive fortnightly cycles. Disease activity was assessed using Harvey-Bradshaw Index, C-reactive protein and faecal calprotectin. For this analysis, trough levels ≥4.9 μg/mL were considered therapeutic.

RESULTS

Nineteen patients underwent 111 evaluations. Mean intra-patient drug levels from paired visits between cycles did not differ (visit1 cycle1: 4.81, cycle2: 5.21 μg/mL, P = 0.24, visit2 cycle1: 4.86, cycle2: 4.82, P = 0.91 and trough cycle1: 3.95, cycle2: 3.95, P = 0.99), irrespective of disease activity. Drug levels were stable over the first 9 days (visit 1-2), but declined to trough by a mean 1.06 and 0.89 μg/mL between visit 1 or 2, respectively (P < 0.001). Models using nontemporal factors (smoking, syringe delivery device) and levels at earlier visits accounted for 66-80% of the variance in trough levels. On receiver-operating curve analysis, thresholds identified in the first 9 days that predicted a therapeutic trough level were similar to the trough threshold itself, with high sensitivity but modest specificity.

CONCLUSION

While therapeutic drug monitoring should be performed at trough, a drug level ≥4.9 μg/mL obtained during the first 9 days predicts a therapeutic trough drug level with reasonable confidence.

Compassionate access anti-tumour necrosis factor-α therapy for ulcerative colitis in Australia: the benefits to patients

BACKGROUND

The efficacy of infliximab has been demonstrated in patients with both acute severe and moderate-severe ulcerative colitis (UC). However, there is a need for 'real-life data' to ensure that conclusions from trial settings are applicable in usual care. We therefore examined the national experience of anti-tumour necrosis factor-α (TNF-α) therapy in UC.

METHODS

Case notes review of patients with UC who had received compassionate access (CA) anti-TNF-α therapy from prospectively maintained inflammatory bowel disease databases of six Australian adult teaching hospitals.

RESULTS

Patients either received drug for acute severe UC (ASUC) failing steroids (n = 29) or for medically refractory UC (MRUC) (n = 35). In ASUC, the treating physicians judged that anti-TNF-α therapy was successful in 20/29 patients (69%); in these cases, anti-TNF-α was able to be discontinued (after 1-3 infusions in 19/20 responders) as clinical remission was achieved. Consistent with this perceived benefit, only 7/29 (24%) subsequently underwent colectomy during a median follow up of 12 months (interquartile range (IQR) 5-16). Eight of the 35 patients with MRUC (23%) required colectomy during a median follow up of 28 months (IQR 11-43). The majority of these patients (20/35 or 57%) had anti-TNF-α therapy for ≥4 months, whereas, 27/29 (93%) of ASUC patients had CA for ≤3 months.

CONCLUSIONS

These data show an excellent overall benefit for anti-TNF-α therapy in both ASUC and MRUC. In particular, only short-duration anti-TNF-α was required in ASUC. These real-life data thus support the clinical trial data and should lead to broader use of this therapy in UC.