Spontaneous Clearance After Relapse Following Direct-Acting Antiviral Treatment for Chronic HCV Infection

BACKGROUND & AIMS: Direct-acting antivirals (DAAs) cure most cases of chronic hepatitis C virus (HCV) infection. However, a small percentage of patients relapse with reappearance of viremia after a full course of therapy. Although most who relapse require retreatment, some patients spontaneously clear HCV without additional therapy. We studied patients who relapsed with detectable HCV RNA after a full course of DAA therapy and then spontaneously cleared the HCV infection without retreatment. METHODS: We performed a case-control study of patients who spontaneously cleared chronic HCV infection following a documented relapse after DAA therapy at the Toronto Centre for Liver Disease, from January 2014 through December 2017. We collected clinical information at baseline, 12 weeks after treatment, and 6 months after relapse and compared data among spontaneous clearers, patients with persistent relapse, and patients who achieved a sustained virologic response to therapy 12 weeks after treatment (SVR12). The strength and breadth of interferon gamma cytokine secretion by HCV-specific T cells from peripheral blood were quantified using the ELISPOT assay. RESULTS: Of the 1032 individuals with chronic HCV infection who were treated with DAAs, 93 patients had a documented relapse. Of these patients, 12 patients (13%) spontaneously cleared HCV within 6 months after the documented relapse without additional therapy. The spontaneous clearers had low levels of HCV RNA (<4 log IU/mL in 11 of 12) and normal levels of alanine aminotransferase at the time of relapse, much like patients with an SVR12. There was no significant difference between the spontaneous clearance group and the SVR12 group in magnitude and breadth of HCV-specific T cell responses. CONCLUSIONS: In a case-control study of patients who spontaneously cleared chronic HCV infection following a relapse after DAA therapy, we found that it is important to confirm viremia prior to retreatment after the relapse-particularly for individuals with low levels of HCV RNA and normal or near-normal levels of alanine aminotransferase after treatment.