Incidence and predictors of direct-acting antiviral treatment failure in Turkish patients with chronic hepatitis C genotype 1b infection

Abstract

Evaluation of the incidence and predictors of failure of direct-acting antiviral treatment for hepatitis C virus genotype 1b patients is important. Our retrospective cohort study assessed 172 Turkish patients who had received a full course of such treatment and could be checked for sustained virologic response. The overall treatment failure rate was 2.9% (5/172), all of whom relapsed. In three of these cases with sequencing data available, all had NS5A resistance-associated substitution. Multivariate analysis revealed that a 1 mg/dL increase in pre-treatment total bilirubin level was associated with a sevenfold increased likelihood of treatment failure. The baseline level of total bilirubin was the only significant independent predictor of direct-acting antiviral treatment failure.

Keywords

Chronic hepatitis C virus infection direct-acting antivirals genotype 1b interferon-free sustained virologic response

Introduction

Hepatitis C virus (HCV) affects nearly 3% of the world population. HCV genotype 1b is the most prevalent HCV sub-type throughout the world as well as in the Turkish population.^1,2 Compared to patients infected with HCV non-1b genotypes, infection with HCV genotype 1b has been shown to be associated with an increased risk of developing advanced liver disease such as hepatocellular carcinoma (HCC) and cirrhosis.³

Achieving a sustained virologic response (SVR) is known to be associated with a remarkable reduction in liver failure-related morbidity and mortality as well as the rate of HCC and need for liver transplantation, even in patients with advanced liver disease.^4,5

Owing to the high rate of SVR reported with interferon (IFN)-free direct-acting antivirals (DAAs), it was expected that hepatitis C might possibly be eradicated in the near future, despite the lack of an approved vaccine for protection from HCV.⁶ However, treatment failure is a barrier to HCV eradication. In spite of the low rates of patients failing to achieve SVR with DAAs, patients are becoming more difficult to treat on account of DAA-specific resistance; in addition, high failure rates in this re-treatment group have led to increased rates of mortality and morbidity as well as increased costs.⁷ Therefore, it is important to identify the negative predictors of response to DAAs.

Unlike IFN-based therapy, SVR in DAAs is generally known to be unaffected by racial differences.⁸ However, more recent evidence suggests these may be present.⁹ Basing clinical trials on racial distinctions is not feasible and so comparison of regional real-life data with clinical trials is needed. There have been only a few studies on outcomes of IFN-free DAA therapy in Turkish HCV genotype 1b patients.^10–12 Consequently, very little is known about the incidence of treatment failure in this group. The aim of the present study was to assess this and possible predictors of virologic failure in a real-life Turkish genotype 1b cohort.

Patients and methods

In this single-centre cohort study, retrospective evaluation was made of 282 patients with genotype 1b chronic hepatitis C (CHC) treated with ledipasvir/sofosbuvir (LDV/SOF) ± RBV or ombitasvir + paritaprevir/ritonavir + dasabuvir (OPrD) between July 2016 and May 2018. Patients who were admitted to the Infectious Disease and Gastroenterology clinics of Mustafa Kemal University Hospital during the study period were included in the SVR analysis if they had completed a full course of DAA therapy and could be checked for SVR 12/SVR 24 (SVR at 12 or 24 weeks after treatment). Patients were excluded if they had incomplete data, a history of non-compliance or were lost to follow-up.

Demographics and all other baseline variables determined and recorded before the initiation of DAA therapy included age, gender, race, history of any co-morbidities, previous HCV treatment failure and chronic medications (for potential drug–drug interactions). The physical examination findings, results of abdominal ultrasound (the presence of cirrhosis, portal hypertension, HCC) and liver biopsy (if available), laboratory test results for viral genotype, baseline viral load, serum alpha fetoprotein (AFP), total bilirubin and alanine aminotransferase (ALT), international normalized ratio (INR) and platelet count were retrieved from the medical records retrospectively.

The treatment regime, duration of therapy (12 or 24 weeks) and RBV addition were chosen by physicians according to the Health Application Communiqué of the Turkish Social Security Institution guideline for DAA treatment of HCV infection (Table 1).¹³

Table 1.

Health Application Communique of the Turkish Social Security Institution’s recommendations for treatment of HCV genotype 1b infection with DAAs.

Patients’ characteristics	Naïve	Experienced
Non-cirrhotic or compensated cirrhosis	OPrD (12 weeks)	OPrD + RBV (12 weeks) or
		LDV/SOF + RBV (12 weeks) or
		LDV/SOF (24 weeks)
Decompensated cirrhosis	LDV/SOF + RBV (12 weeks) or	LDV/SOF + RBV (12 weeks) or
	LDV/SOF (24 weeks)	LDV/SOF (24 weeks)

DAAs, direct-acting antivirals; HCV, hepatitis C virus; LDV/SOF, ledipasvir + sofosbuvir; OPrD, ombitasvir + paritaprevir/ritonavir + dasabuvir; RBV, ribavirin.

HCV ribonucleic acid (HCV RNA) levels at 4 and 12 weeks of therapy and 12–24 weeks after treatment were obtained to evaluate outcomes. Patients were categorized as SVR (n = 167) and non-SVR (n = 5) groups according to the treatment response. Baseline and outcome data were compared between the groups.

The study included 116 genotype 1b patients treated with LDV/SOF ± RBV and 56 genotype 1b patients treated with OPrD.

SVR was defined as undetectable viral load at 12–24 weeks after cessation of treatment. The non-SVR patient group included relapsed cases and those with a positive HCV RNA result at weeks 12–24 after treatment. Early virologic response (EVR) was defined as an undetectable HCV RNA at treatment week 4. Patients with cirrhosis were identified based on the presence of one of the following criteria: ultrasound confirmed cirrhosis and/or histological evidence of cirrhosis (F4). Decompensated cirrhosis was defined by the presence of ascites, splenomegaly or oesophageal varices.

HCV genotype and viral load level were determined with a real-time polymerase chain reaction (PCR) HCV assay (COBAS AmpliPrep/COBAS TaqMan, Roche Diagnostics, Germany) with a detection limit of 15 IU/mL.

Approval for the study was granted by the Ethics Committee of Mustafa Kemal University Hospital (decision date: 11 June 2018, number: 09).

Statistical analyses were performed using the SPPS version 23 software (SPSS, Inc., Chicago, IL, USA). The univariate comparisons to identify variables associated with antiviral treatment failure were performed using the Chi-squared, Fisher’s exact, Student’s t and Mann–Whitney U tests, where appropriate. The possible factors identified with univariate analyses including age, gender, prior treatment experience, EVR, pre-treatment serum levels of ALT, total bilirubin, HCV RNA and platelet count were entered into a logistic regression model to identify independent predictive factors for non-response in genotype 1b patients. The model fit was assessed using the Hosmer and Lemeshow goodness-of-fit test. The Wald statistic was used to evaluate the statistically significance for independent variables. The model was statistically significant (R²= 28,348, P = 0.051). The model explained 40.4% (Nagelkerke R²) of the variance in non-responsiveness and correctly classified 97.1% of cases. For all comparisons, a value of P < 0.05 was considered statistically significant.

Results

A total of 172 patients were included (62.8% women, 37.2% men; median age = 65 years); 30.8% had cirrhosis (41.5% of whom had decompensated liver disease) and 14% had at least one co-morbidity (2.9% had diabetes, 4.7% had a GFR <30 mL/min/1.73 m²). During follow-up, one patient developed HCC and two underwent liver transplantation (Table 2).

Table 2.

A comparison of the variables associated with treatment failure in patients (overall and according to treatment regimens) (n = 172).

Characteristics	Overall	LDV/SOF ± RBV group (n = 116)	OPrD group (n = 56)	P value
Age (years)	65 (59.0–71.0)	67 (60.2–72.0)	62 (54.2–67.7)	<0.01*
Age (years)
<65	80 (46.6)	44 (37.9)	36 (64.3)	<0.01*
≥65	92 (53.4)	72 (62.1)	20 (35.7)
Gender
Male	64 (37.2)	43 (37.1)	21 (37.5)	0.956
Female	108 (62.8)	73 (62.9)	35 (62.5)
Any co-morbidity	24 (14)	11 (9.5)	13 (23.2)	0.015*
Prior treatment
No	79 (45.9)	40 (34.5)	38 (69.6)	<0.01*
Yes	93 (54.1)	76 (65.5)	17 (30.4)
HCV RNA (IU/mL)
<800.000	100 (58.1)	68 (58.6)	32 (57.1)	0.854
≥800.000	72 (41.9)	48 (41.4)	24 (42.9)
Cirrhosis
No	119 (69.2)	71 (61.2)	48 (85.7)	<0.01*
Yes	53 (30.8)	45 (38.8)	8 (14.3)
Albumin (g/L)	38 (35–42)	37.8 (32–41)	40 (37.8–43.9)	<0.01*
Total bilirubin (g/L)	8.1 (5.4–10.2)	8.3 (5.2–11.3)	7 (5.4–9.2)	0.248
ALT (IU/L)	38 (24.0–60.7)	39 (25.0–61.0)	37 (21.0–49.0)	0.208
INR	1.07 (1.0–1.1)	1.08 (1.0–1.1)	1.04 (0.9–1.1)	0.075
Platelets (×10⁹/L)	198.67 (142.5–250.5)	180.50 (128.5–253.0)	212.5 (188.5–247.0)	0.029*

Values are given as n (%) for categorical variables and median (IQR) for continuous variables.

Statistically significant.

ALT, alanine amino transferase; HCV RNA, hepatitis C virus ribonucleic acid; INR, international normalised ratio; IQR, interquartile range; LDV/SOF, ledipasvir + sofosbuvir; OPrD, ombitasvir + paritaprevir/ritonavir + dasabuvir; RBV, ribavirin.

In the LDV/SOF ± RBV group (n = 116), the majority (95.6%) received LDV/SOF alone while all patients in the OPrD group (n = 56) received OPrD without RBV. All patients who had decompensated cirrhosis were treated with LDV/SOF ± RBV, but not with OPrD.

The number of patients with at least one co-morbidity was significantly higher in the OPrD group (23.2%) than in the LDV/SOF ± RBV group (9.5%) (P = 0.015) (Table 2).

The overall treatment failure rate was 2.9%. The treatment failure rate in cirrhotic patients for LDV/SOF ± RBV and OPrD were 4.5% and 0%, respectively. These rates were 0% and 6.3% in non-cirrhotic patients, respectively.

Virologic relapse occurred in 2.9% (5/172) of patients, although no virologic breakthrough was observed. All the five cases (four women, one man; median age = 68.2 years) who relapsed did so at 12–24 weeks after cessation of therapy: one had decompensated cirrhosis; one had serious co-morbidity; four had no EVR; and none of the relapsed cases received RBV. The rates of EVR were similar in the two treatment groups: 56 LDV/SOF ± RBV (48.3%) and 34 OPrD (60.7%) (P = 0.126).

In the multivariate analysis, a 1-mg/dL increase in pre-treatment total bilirubin level was associated with a 7.1-fold increased likelihood of treatment failure (odds ratio [OR] = 7.192, 95% confidence interval [CI] = 1.324–92.238; P = 0.026). Age, gender, prior treatment failure, EVR, pre-treatment serum levels of ALT, HCV RNA and platelet count did not predict treatment failure (Table 3).

Table 3.

Multivariable model for treatment failure.

Variable	OR for failure		P value
	OR	95% CI	P value
Age	1.110	0.975–1.264	0.113
Gender	0.018	0.000–3.894	0.143
Prior treatment experience	0.925	0.095–8.997	0.947
EVR	5.064	0.415–61.767	0.204
Pre-treatment serum levels of ALT	0.996	0.951–1.044	0.877
Pre-treatment serum levels of total bilirubin	7.192	1.308–39.549	0.023*
HCV RNA	1.268	0.117–13.698	0.845
Platelet count	1.002	0.986–1.019	0.783

Statistically significant.

ALT: alanine amino transferase; CI, confidence interval; EVR, early virologic response; HCV RNA, hepatitis C virus ribonucleic acid; OR, odds ratio.

The data of sequence analysis for the NS5A region was known in 3/5 relapsed cases and all had resistance-associated substitutions (RAS) in the NS5A gene (polymorphisms at positions L28M, P58S and Y93H) at the time of failure, which caused resistance to daclatasvir, elbasvir, ledipasvir, ombitasvir and velpatasvir, but not to pibrentasvir.

Discussion

Very little is known about the incidence and predictors of treatment failure with IFN-free DAAs in Turkish patients with chronic HCV genotype 1b infection.

The risk of treatment failure was low (2.9%) in the present study, similar to those observed in previous clinical trials and compatible with other real-world analyses from different populations.^14–17

Numerous genetic sequence polymorphisms may emerge during DAA therapy in subtype-1b patients, which may cause resistance to DAA administered; this is known as RAS.¹⁸ In the present study, virologic relapse occurred in only five of 172 patients at 12–24 weeks after cessation of therapy, of whom all three cases with available sequencing data had NS5A RASs at the time of failure, causing resistance to all NS5A inhibitors, except pibrentasvir. This result is consistent with previous findings showing that the selection of RASs within the quasi-species is a common finding in relapsed cases.¹⁹

Traditional risk factors associated with a worse response to IFN-based HCV therapy seem to be no longer relevant in outcomes with IFN-free DAA.^20,21 Consistent with previous findings, the treatment outcomes in the present cohort study were not significantly influenced by age, gender, prior treatment failure, EVR, co-morbidities, cirrhosis status, pre-treatment serum levels of ALT, HCV RNA or platelet count.

Those patients who received the OPrD regimen had a higher rate of treatment failure than those who received LDV/SOF ± RBV (15.4% and 8%, respectively). This may be explained by a significantly higher proportion of patients with co-morbidities in the former, though multivariable analysis showed co-morbidity not to be a factor. In fact, patients receiving the OPrD regimen were 40% less likely to achieve SVR compared those receiving LDV/SOF.^22,23 Nevertheless, our findings are limited by the relatively low number of patients in the OPrD regimen group, possibly leading to an overestimation of absolute risk.

We found that the baseline total bilirubin level was an independent predictive factor of treatment failure. For each 1.0 mg/dL increase in baseline total bilirubin level, there was a sevenfold increase in risk of failure, as found previously.^24,25 However, serum total bilirubin level is not generally considered sensitive enough to indicate the severity of liver disease; they may be within normal range in well-compensated cirrhosis. Nevertheless, they do tend to be elevated with decompensated liver disease.²⁶ Thus, higher rates of virologic failure observed in patients with a high baseline total bilirubin level suggest a reduced baseline functional reserve.

Although an EVR (undetectable serum HCV RNA level at week 4) was a predictive factor of SVR in the IFN era, the effect of viral kinetics during IFN-free DAA therapy on SVR has been fully clarified.^27–29 Although EVR did not seem to affect SVR in our study, the lowest failure rate (1.2%) was observed in patients with EVR. Recent experimental evidence has shown that viral load falls more rapidly with DAA than with IFN-based therapy, especially during the first 14 days of treatment.³⁰ Therefore, investigating for undetectable HCV RNA levels at four weeks of therapy may be too late for the prediction of treatment response in IFN-free DAA therapy.³¹ Further information on viral kinetics would give better understanding of whether or not achieving a rapid decline in viral level (vRVR) is useful for the prediction of SVR in DAA therapy.

The major limitation of our study was the limited number of cases in the non-SVR group. This could simply be attributed to the rarity of non-responsiveness to DAAs in clinical practice. The retrospective nature and the heterogeneous treatment regimens, however, mean that our findings do need to be interpreted with caution.

Footnotes

Acknowledgements

This study was presented as an oral presentation at the 7th EKMUD Scientific Platform (3–7 April 2019, Antalya, Turkey).

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Tayibe Bal

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