The use of direct-acting antivirals (DAAs) to treat chronic hepatitis C has resulted in a significant increase in rates of sustained viral response (around 90%-95%) as compared with the standard treatment of peginterferon/ribavirin. Despite this, however, the rates of therapeutic failure in daily clinical practice range from 10%-15%. Most of these cases are due to the presence of resistant viral variants, resulting from mutations produced by substitutions of amino acids in the viral target protein that reduce viral sensitivity to DAAs, thus limiting the efficacy of these drugs. The high genetic diversity of hepatitis C virus has resulted in the existence of resistance-associated variants (RAVs), sometimes even before starting treatment with DAAs, though generally at low levels. These pre-existing RAVs do not appear to impact on the sustained viral response, whereas those that appear after DAA therapy could well be determinant in virological failure with future treatments. As well as the presence of RAVs, virological failure to treatment with DAAs is generally associated with other factors related with a poor response, such as the degree of fibrosis, the response to previous therapy, the viral load or the viral genotype. Nonetheless, viral breakthrough and relapse can still occur in the absence of detectable RAVs and after the use of highly effective DAAs, so that the true clinical impact of the presence of RAVs in therapeutic failure remains to be determined.

Vedolizumab is a humanized IgG1 monoclonal antibody that selectively blocks the lymphocyte integrin α4β7 and prevents its interaction with endothelial adhesion molecules and subsequent transmigration to the gastrointestinal tract. The drug was approved in 2014 for the induction and maintenance treatment of ulcerative colitis and moderate to severe Crohn's disease that is refractory or intolerant to conventional treatment with corticoids and immunosuppressants and/or anti-TNFα drugs. However, inflammatory bowel disease has a variable behavior following liver transplant. One third of patients with ulcerative colitis associated with primary sclerosing cholangitis are expected to deteriorate despite receiving immunosuppression to prevent rejection. There is limited experience with anti-TNFα agents in patients with inflammatory bowel disease in the setting of liver transplantation and the studies to date involve a limited number of cases. The efficacy and safety data of vedolizumab in this situation are unreliable and very preliminary. We present two cases with the aim to present the efficacy and safety of vedolizumab after one year of treatment in two patients who underwent a transplant due to primary sclerosing cholangitis. One case had de novo post-transplant ulcerative colitis refractory to two anti-TNFα drugs (golimumab and infliximab). The other patient had a colostomy due to fulminant colitis and developed severe ulcerative proctitis refractory to infliximab after reconstruction with an ileorectal anastomosis.

Background: ustekinumab has proven effective in Crohn's disease (CD). However, some patients will partially respond or lose response over time. Data supporting the effective-ness of dose escalation in this scenario is scarce.Aim: to evaluate the effectiveness of ustekinumab dose es-calation in CD.Methods: patients with active CD (Harvey-Bradshaw >= 5) who had received intravenous (IV) induction and at least a subcutaneous (SC) dose were included in this retrospective observational study. Ustekinumab dose was escalated, ei-ther via shortening of the interval to six or four weeks or IV reinduction plus shortening to every four weeks.Results: ninety-one patients were included, and ustekinumab dose was escalated after a median of 35 weeks of treatment. At week 16 after intensification, steroid-free clinical response and remission were observed in 62.6 % and 25.3 % of patients, respectively. Systemic corticosteroids were discontinued in 46.7 % of patients who were on corticosteroids at baseline. Follow-up data beyond week 16 were available for 78 % of patients; at the last visit, 66.2 % and 43.7 % were in steroid-free clinical response and remission, respectively. After a median follow-up of 64 weeks, 81 % of patients were still treated with ustekinumab. Ad-verse events were reported in 4.3 % of patients; these were all mild and did not lead to hospitalization or discontinuation of treatment. Five patients (5.5 %) underwent surgical resection, with no immediate postsurgical complications. Conclusion: ustekinumab dose escalation was effective in recapturing response in over half of the patients. These findings suggest that dose escalation should be considered in patients who experience loss or partial response to the standard maintenance.