Treatment of chronic hepatitis C with direct-acting antivirals: The role of resistance.

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.

[Pulmonary toxicity associated with sirolimus therapy in liver transplantation]. / Toxicidad pulmonar asociada a sirolimus en el trasplante hepático.

Sirolimus is a potent immunosuppressive drug that began to be used in the last few years. This drug was initially used in renal transplantation but its use in other solid organ transplantations such as liver, heart, lung and pancreas, has been increasing. Sirolimus is indicated in rescue therapies and to reduce the secondary toxic effects of calcineurin inhibitors. However, this drug has been associated with infrequent but severe pulmonary toxicity and cases of interstitial pneumonitis, bronchiolitis obliterans with organizing pneumonia, and alveolar proteinosis have been described. We present the case of a male liver transplant recipient who developed interstitial pneumonitis associated with sirolimus use.