Long-term oral tacrolimus therapy in refractory to infliximab fistulizing Crohn's disease: a pilot study.

AIMS: To evaluate efficacy and safety of oral tacrolimus in cases of fistulizing Crohn's disease (FCD), which is refractory to conventional therapy including infliximab.

METHODS: Patients with fistulas, previously and unsuccessfully treated with all conventional therapy (i.e., antibiotics, azathioprine, or 6-mercaptopurine and infliximab), were enrolled in a prospective, uncontrolled, open-label study of long-term treatment with oral tacrolimus (0.05 mg/kg every 12 h). The evaluation of the clinical response was complemented by use of the perianal Crohn's disease activity index (PCDAI) and magnetic resonance imaging-based score (MRS) with determined periodicity.

RESULTS: Ten patients were included in the study (enterocutaneous fistula, 3 patients; perianal fistula, 4 patients; rectovaginal fistula, 3 patients) with 6 to 24 months of follow-up. Five patients were steroid-dependent, and 4 patients needed maintenance treatment with immunosuppressant agents. Four patients (40%) achieved complete clinical responses, which were verified by PCDAI and MRS. Five patients (50%) achieved partial responses (i.e., important decreases in fistula drainage, size, discomfort, and PCDAI/MRS values). Decreases in both the PCDAI and MRS were statistically significant (P < 0.05). All steroid-dependent patients stopped therapy with prednisone, and concomitant immunosuppressive therapy was tapered. The response was maintained, and no new flare-up of the disease was observed. Only mild adverse events were detected (1 patient withdrew from treatment due to headache), and no case of nephrotoxicity or diabetes was detected. One patient had received no benefit from therapy after 6 months.

CONCLUSIONS: Oral tacrolimus could be an effective and safe treatment for patients with FCD, even if there has been no response to infliximab treatment. Randomized studies are needed to compare oral tacrolimus with infliximab in terms of efficacy, safety, and costs.