Protein Expression May Predict HBV DNA Suppression

Neil Osterweil

July 08, 2021

Stopping nucleoside analog therapy in patients with hepatitis B viral (HBV) infections results in sustained viral suppression in only a minority of patients, but a new study suggests there are immune signatures that may serve as predictive biomarkers to help clinicians determine how to improve immune responses in these patients, according to investigators.

In a study of 359 patients enrolled in clinical trials of antiviral therapy for HBV infections, there were 29 immune-related proteins that were found in significantly higher levels among patients who continued to have viral suppression 24 weeks after the end of treatment, compared with patients who did not maintain viral suppression, reported Henry L.Y. Chan, MD, from the Chinese University of Hong Kong.

"In this study, plasma proteomics shows that sustained HBV suppression following treatment discontinuation is associated with higher levels of innate and adaptive immune responses during treatment, but whether these signatures vary by specific treatment regimens remains to be determined," he said in an oral session at the meeting sponsored by the European Association for the Study of the Liver.

The clustering of proteins differed between patients treated with nucleoside analogs and those who received pegylated interferon (PEG-IFN), Chan noted.

Is It safe?

Although current international guidelines say that clinicians may consider stopping nucleoside analogs in certain patient populations with the goal of promoting sustained off-treatment responses, pooled data from four large phase 3 studies showed that only 10% of patients had sustained HBV DNA suppression, and only 32% had persistent low-level viremia, Chan said, citing a presentation from ILC in 2019.

Chan and colleagues sought to identify immune biomarkers that at the end of treatment predict HBV off-treatment response. This is important because existing treatments do not kill the virus which – even if suppressed – can lead to hepatocellular carcinoma.

The researchers examined plasma samples from patients with chronic hepatitis B who were enrolled in two studies: a registrational study comparing tenofovir disoproxil fumarate with adefovir followed by tenofovir maintenance (GS-US-174-0102) and one comparing TDF plus PEG-IFN with either drug alone (GS-US-174-0149).

They identified a total of 359 patients who had at least two treatment-free follow-up visits, were positive for the hepatitis B S antigen (HBsAg) at the end of the treatment, including patients who had antigen loss on treatment but subsequently seroverted, and had available plasma samples collected before the end of treatment.

The study outcomes were sustained viral suppression 24 weeks after the end of treatment, defined as HBV DNA less than 29 IU/mL, and a low replicative state defined as HBV DNA below 2,000 IU/mL with ALT levels at or below the upper limit of normal.

The median patient age was 39 years. In all, 67% of the population was male, and 70% were Asian.

Immune-Related Proteins

The investigators performed proteomic analyses looking for expression levels in serum or plasma proteins at the end of treatment.

A total of 25 patients had HBV DNA suppression at posttreatment week 24, 111 patients had a low replicative states, and 4 had HBsAg loss.

The patients with HBV DNA suppression had significantly higher expression of 29 immune-related proteins, the majority of which were related to the host immune response.

The proteins included myeloid cell markers, leukocyte-trafficking chemokines, natural killer cell markers, and extracellular matrix and/or extracellular matrix–associated proteins.

Among patients with HBV suppression, there was evidence of enrichment for extracellular remodeling pathways, as well as pathways involved in innate immune response to viral infections and immune regulation.

Among patients with low viral replication, there was a trend toward higher CD8a expression levels at the 24-week follow-up, but there were no proteins with significantly elevated expression levels.

"Assessment of unique protein signatures associated with HBsAg loss following treatment discontinuation is ongoing," Chan said.

Timing of Expression Patterns

During the question-and-answer session following his presentation, comoderator Pablo Sarobe, MD, from the Clinica Universidad de Navarra (Spain), said: "I've seen that you have compared the different proteins which are detected in your cell samples 24 weeks after stopping treatment. Do you think that these differences are already relevant just at the end of treatment, or that these proteins are being expressed [during] the 24 weeks between the end of treatment and your determination?"

"We only have one time-point sample, so it's hard to say," Chan replied, but he speculated that the delay would not have a direct impact on protein expression, "so probably this expression should last after treatment has stopped. But we only have only posttreatment 24-week data, and we believe that some of the outcome measures may change with longer follow-up. After 1 year some patients in suppression may relapse."

Asked by an audience member whether the investigators had performed a subanalysis of patients treated with nucleoside analogs, Chan noted that such an analysis was under consideration, although the patient numbers were relatively small. He did add, however, that protein expression patterns differed among patients treated with nucleoside analogs and PEG-IFN.

The study was funded by Gilead Sciences. Chan disclosed sponsored lecture activities and consulting for Gilead and others. Sarobe reported no conflicts of interest.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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