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Influence of ITPA polymorphisms on decreases of hemoglobin during treatment with pegylated interferon, ribavirin, and telaprevir - pdf attached
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Download the pdf here
Hepatology Jan 26 2011 early view
Fumitaka Suzuki,1 Yoshiyuki Suzuki,1 Norio Akuta,1 Hitomi Sezaki,1 Miharu Hirakawa,1 Yusuke Kawamura,1 Tetsuya Hosaka,1 Masahiro Kobayashi,1 Satoshi Saito,1 Yasuji Arase,1 Kenji Ikeda,1 Mariko Kobayashi,2 Kazuaki Chayama,3 Naoyuki Kamatani,4 Yusuke Nakamura,5 Yuzo Miyakawa,6 and Hiromitsu Kumada1
From the 1Department of Hepatology, Toranomon Hospital, Tokyo, Japan; 2Research Institute for Hepatology, Toranomon Hospital, Tokyo, Japan; 3Department of Medical and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Science, Hiroshima University, Hiroshima, Japan; 4Laboratory for Statistics, RIKEN Center for Genomic Medicine, Yokohama, Japan; 5Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan; 6Miyakawa Memorial Research Foundation,Tokyo, Japan.
Supported in part by grants from the Japanese Ministry of Health, Labour and Welfare.
Address reprint requests to: Fumitaka Suzuki, Department of Hepatology, Toranomon Hospital, 1-3-1, Kajigaya, Takatsu-ku, Kawasaki City 213-8587, Japan. E-mail: fumitakas@toranomon.gr.jp; fax: 81-44-860-1623.
"Triple therapy for 12 weeks, followed by PEG-IFN and RBV for 12 weeks, was given to 49 patients with RBV-sensitive (CC at rs1127354) and 12 with RBV-resistant (CA/AA) ITPA genotypes who had been infected with hepatitis C virus (HCV) of genotype 1. Decreases in hemoglobin levels were greater in patients with CC than CA/AA genotypes at week 2 (-1.63 ± 0.92 vs. -0.48 ± 0.75 g/dL, P = 0.001) and week 4 (-3.5 ± 1.1 vs. -2.2 ± 0.96, P = 0.001), as well as at the end of treatment (-2.9 ± 1.1 vs. -2.0 ± 0.86, P = 0.013)"
"Telaprevir was discontinued in 10 of the 49 (20%) patients with CC and 5 of the 12 (42%) with CA/AA genotypes (P = 0.147)......SVR was achieved by 35 (71%) of the 49 patients with CC and 8 (67%) of the 12 with CA/AA genotypes (P = 0.736)......Of the 32 patients with TT genotype of the IL28B gene at rs8099917, 30 (94%) gained SVR, more frequently than 10 of the 26 (38%) with TG/GG genotypes (P< 0.001). Likewise, 29 of the 30 (97%) patients with CC genotype at rs12979860 achieved SVR, more frequently than 11 of the 27 (41%) with CT/TT genotypes (P< 0.001)......In confirmation of our previous report,28 the triple therapy achieved SVR more frequently in patients with CC than CT/TT genotypes of IL28 at rs12979860 (96% vs. 41%, P< 0.001). About two-thirds of studied patients accomplished SVR with the triple treatment, although one-fourth of them were nonresponders to previous IFN-based treatments; they are known to respond poorly to repeated treatments. This would lend further support to the efficacy of triple therapy being higher than treatment with pegylated IFN and RBV."
"There are strong points in this study. First, ITPA polymorphisms influence RBV-induced anemia in the triple therapy. Second, polymorphisms at rs1127350, without involvement of those at rs7270107, protect against RBV-induced anemia. Third, the triple therapy can be applied with high efficacy by careful monitoring of hemoglobin and prompt modification of RBV dose. There are weak points in this study as well. First, it was a retrospective cohort study conducted in a small size of patients, especially those with CA/AA genotypes at rs1127350, and included null-responders to previous IFN-based therapies; the real impact of ITPA polymorphisms on RBV-induced anemia may have been obscured. Second, the study was conducted in Japanese patients, and the results may or may not be extended to patients of different ethnicities with distinct genetic backgrounds. Hopefully, the results presented herein will promote future studies in which the influence of the ITPA polymorphism on RBV-induced anemia will be pursued in larger scale and on patients of various ethnicities around the world."
ABSTRACT
Polymorphisms of the inosine triphosphatase (ITPA) gene influence anemia during pegylated interferon (PEG-IFN) and ribavirin (RBV) therapy, but their effects during triple therapy with PEG-IFN, RBV, and telaprevir are not known. Triple therapy for 12 weeks, followed by PEG-IFN and RBV for 12 weeks, was given to 49 patients with RBV-sensitive (CC at rs1127354) and 12 with RBV-resistant (CA/AA) ITPA genotypes who had been infected with hepatitis C virus (HCV) of genotype 1. Decreases in hemoglobin levels were greater in patients with CC than CA/AA genotypes at week 2 (-1.63 ± 0.92 vs. -0.48 ± 0.75 g/dL, P = 0.001) and week 4 (-3.5 ± 1.1 vs. -2.2 ± 0.96, P = 0.001), as well as at the end of treatment (-2.9 ± 1.1 vs. -2.0 ± 0.86, P = 0.013). Risk factors for hemoglobin <11.0 g/dL at week 4 were female gender, age >50 years, body mass index (BMI) <23, and CC at rs1127354 by multivariate analysis. RBV dose during the first 12 weeks was smaller in patients with CC than CA/AA genotypes (52 ± 14% vs. 65 ± 21% of the target dose, P = 0.039), but the total RBV dose was no different between them (49 ± 17% and 54 ± 18% of the target, P = 0.531). Sustained virological response (SVR) was achieved in 70% and 64% of them, respectively (P = 0.724). Conclusion:ITPA polymorphism influences hemoglobin levels during triple therapy, particularly during the first 12 weeks while telaprevir is given. With careful monitoring of anemia and prompt adjustment of RBV dose, SVR can be achieved comparably frequently between patients with CC and CA/AA genotypes. (Hepatology 2011)
Worldwide, 123 million people are estimated to have been infected with hepatitis C virus (HCV),1 and ≈30% of them develop fatal liver disease such as cirrhosis and hepatocellular carcinoma.2, 3 Currently, the standard of care therapy for patients infected with HCV is pegylated interferon (PEG-IFN) and ribavirin (RBV) for 48 weeks.4-6 However, the combined treatment can induce a sustained virological response (SVR), judged by the loss of detectable HCV RNA from serum 24 weeks after treatment completion, in at most 50% of patients infected with HCV-1, the genotype most prevalent and least responsive to IFN-based therapies.
Recently, Fellay et al.7 reported that polymorphisms of the inosine triphosphatase (ITPA) gene in chromosome 20 (20p13) influence RBV-induced anemia in a genome-wide association study (GWAS). Single nucleotide polymorphism (SNP) at rs1127354 for proline-to-threonine substitution (P32T) in the second of eight exons in the ITPA gene, as well as that at rs7270101 in the second intron, affects the expression of ITPA.8-11 Patients infected with HCV-1 carrying the CC genotype at rs1127354 are more prone to develop anemia than those with CA/AA genotypes during the combination therapy, and the decrease in hemoglobin is greater in patients with the AA than AC/CC genotypes at rs7270101.7 Their observations have been extended to many patients in a large-scale trial with pegIFN-α-2a on Caucasian and African Americans,12 as well as in the Japanese receiving PEG-IFN-α-2b and RBV who were infected with HCV-1.13
For improving SVR in HCV-1 patients, protease inhibitors have been added to the standard treatment with PEG-IFN and RBV, and increased SVR by ≈20%.14-16 However, such a gain in efficacy is not without trade-offs, represented by aggravation of anemia. Early decreases in hemoglobin levels during the triple therapy reach 4 g/dL, and they exceed ≈3.0 g/dL in the standard treatment.14, 15 Because there have been no reports focusing on the influence of ITPA genotypes on anemia developing in patients during triple therapy, hemoglobin levels were followed in 61 Japanese patients with HCV-1 who had received it. The results were correlated with polymorphisms at rs1127354 in the ITPA gene because the Japanese are monoallelic at rs7270101 and have the AA genotype exclusively.11
RESULTS
Triple Therapy in Patients with HCV-1 Infection.
Baseline characteristics of the 49 patients with CC and the 12 with CA/AA genotypes at rs1127354 in the ITPA gene are compared in Table 1. They all were infected with HCV-1. There were no significant differences between them, except that alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were higher in patients with CC than CA/AA genotypes (P = 0.041 and P = 0.008, respectively). Overall, IL28B genotypes resistant to PEG-IFN and RBV, TT/TG at rs8099917, and CC/CT at rs12979860 were rather frequent, and possessed by 44% and 47%, respectively, of the patients. This was due to inclusion of 15 nonresponders to previous IFN-based therapies, corresponding to 25% of the 61 patients studied, most of whom (14/15 [93%]) possessed IFN-resistant genotypes (TT/TG and CC/CT). Six of them had low hemoglobin levels (<13 g/dL) at baseline and were started with an RBV dose decreased by 200 mg; they included five with CC and one with CA genotypes of the ITPA gene.
Modification of RBV Dose During Triple Therapy.
RBV dose was reduced by ≥200 mg in all 61 patients studied during triple therapy because hemoglobin had decreased <12.0 g/dL in them. During the first 12 weeks of therapy while telaprevir was given, the proportion of patients receiving the full RBV dose differed between those with CC and CA/AA genotypes (Fig. 1). RBV dose reduction was started earlier in the 49 patients with CC than the 12 with CA/AA genotypes (2.6 ± 1.3 vs. 4.8 ± 3.1 weeks after the start, respectively, P = 0.010). Thus, during the first 12 weeks with telaprevir the RBV dose was smaller in patients with CC than CA/AA genotypes (52 ± 14% vs. 65 ± 21% of the target dose, P = 0.039). During the next 12 weeks without telaprevir, in contrast, the RBV dose was somewhat larger in patients with CC than CA/AA genotypes (47 ± 24% vs. 43 ± 20%, P = 0.649). The total RBV dose during 24 weeks on therapy was comparable between the 49 patients with CC and the 12 with CA/AA genotypes (49 ± 17% vs. 54 ± 18%, P = 0.531). In patients with the CC genotype, the RBV dose was no different between those who achieved SVR and those who did not (50 ± 18% vs. 47 ± 13%, P = 0.728). The RBV dose did not differ either in patients with CA/AA genotypes with and without SVR (57 ± 17% vs. 48 ± 20%, P = 0.368).
The total dose of PEG-IFN was comparable among 49 patients with CC and 12 with CA/AA genotypes (87 ± 23% vs. 86 ± 20% of the target, P = 0.488). The total telaprevir dose was no different either between them (87 ± 27% vs. 71 ± 36% of the target, P = 0.098). Telaprevir was discontinued in 10 of the 49 (20%) patients with CC and 5 of the 12 (42%) with CA/AA genotypes (P = 0.147).
Decreases in Hemoglobin Levels During Triple Therapy.
Figure 2 compares decreases in hemoglobin levels between 49 patients with CC and 12 with CA/AA genotypes of the ITPA gene. Data of six patients were omitted because the triple therapy was withdrawn 4-10 weeks after the start, including five with CC and one with CA genotype. Hemoglobin decreased more in patients with CC than CA/AA genotypes at week 2 (-1.63 ± 0.92 vs. -0.48 ± 0.75 g/dL, P = 0.001) and week 4 (-3.5 ± 1.1 vs. -2.2 ± 0.96, P = 0.001). During week 8 through 12, hemoglobin reached the nadir of approximately -4 g/dL both in patients with CC and CA/AA genotypes. Thereafter, differences in hemoglobin decrease started to widen between patients with CC and CA/AA genotypes and were significant at week 20 (-3.0 ± 1.2 vs. -2.4 ± 0.88 g/dL, P = 0.048) and week 24 (-2.9 ± 1.1 vs. -2.0 ± 0.85 g/dL, P = 0.013).
SVR was achieved by 35 (71%) of the 49 patients with CC and 8 (67%) of the 12 with CA/AA genotypes (P = 0.736). Hemoglobin levels did not differ between them 24 weeks after the completion of triple therapy (-0.57 ± 1.1 vs. -0.17 ± 0.87 g/dL, P = 0.271). Of the 32 patients with TT genotype of the IL28B gene at rs8099917, 30 (94%) gained SVR, more frequently than 10 of the 26 (38%) with TG/GG genotypes (P< 0.001). Likewise, 29 of the 30 (97%) patients with CC genotype at rs12979860 achieved SVR, more frequently than 11 of the 27 (41%) with CT/TT genotypes (P< 0.001).
Factors Influencing Decreases in Hemoglobin Levels.
Hemoglobin decreased <11 g/dL at week 4 during the triple therapy in 27 of the 61 (44%) patients. Factors for hemoglobin <11.0 g/dL were female gender, age >50 years, body weight <60 kg, BMI <23, and baseline hemoglobin <15 g/dL, as well as the CC genotype of the ITPA gene, in the univariate analysis (Table 2). Of them, female gender, age >50 years, BMI <23, and the CC genotype remained significant in the multivariate analysis. Hemoglobin levels lowered <8.5 g/dL during the triple therapy in 13 of the 61 (21%) patients. Factors for hemoglobin <8.5 g/dL were female gender, age >60 years, body weight <60 kg, BMI <23, and baseline hemoglobin <14 g/dL in the univariate analysis (Table 3). Of them, only age and body weight remained significant in the multivariate analysis.
DISCUSSION
Anemia is a substantial risk in the standard of care therapy with PEG-IFN and RBV.4-6 Triphosphorylated RBV accumulates in erythrocytes of patients who receive RBV, increasingly with RBV dose and duration, and causes oxidative damage to erythrocyte membranes toward extravascular hemolysis by the reticuloendothelial system.19, 20 Inosine triphosphate accumulates also in erythrocytes of individuals who have mutations in the ITPA gene, and results in benign red-cell enzymopathy.8 The expression of ITPA is genetically controlled and reduced in individuals who have point mutations in the ITPA gene.8-11 As another achievement of GWAS in hepatology,21 in the wake of polymorphisms of the IL28B gene that influence the response to PEG-IFN and RBV,22-24 polymorphisms in the ITPA gene has been reported to influence anemia caused by RBV.7 How inosine triphosphate protects erythrocytes from hemolysis caused by RBV needs to be sorted out by in vivo and in vitro experiments. Inosine triphosphate may prohibit the accumulation of RBV in erythrocytes, or rather, it might act directly toward prohibition of hemolysis.
In the present study, 61 patients infected with HCV-1 received triple therapy with PEG-IFN, RBV, and telaprevir in the first 12 weeks followed by PEG-IFN and RBV in the second 12 weeks. Then the RBV dose and hemoglobin were compared between patients with CC and CA/AA genotypes in the ITPA gene. Two polymorphisms in the ITPA gene, in close linkage disequilibrium with an r2 value of 0.65,7 have been recognized in Caucasians (rs1127354 and rs7270107); the respective CA/AA and AC/CC genotypes decrease the activity of inosine triphosphatase and protect against anemia induced by RBV.7, 12 Because the Japanese are monoallelic at rs7270107 and possess the AA genotype exclusively,11, 25 only polymorphisms at rs1127354 were examined.
Of the 61 patients, 49 possessed the RBV-sensitive CC genotype and the remaining 12 had RBV-resistant CA/AA genotypes. Hemoglobin levels decreased both in patients with CC and CA/AA genotypes. They lowered ≈4 g/dL during weeks 8-12 on the triple therapy with telaprevir, and increased thereafter (Fig. 2). Between the two groups of patients, differences in hemoglobin decrease were greatest at week 4 (1.3 g/dL), as in the standard treatment with PEG-IFN and RBV.7, 12, 13
When anemia and other side effects occurred, doses of RBV, PEG-IFN, and telaprevir were modified. Of the 61 patients studied, 27 (44%) were women and most of them were in old age. Beyond 50 years of age, women are less responsive than men to the standard treatment with PEG-IFN and RBV, probably because estrogens with an antifibrotic potential decrease after menopause.26 Stringent precautions had to be taken, therefore, by reducing the RBV dose in the patients in whom hemoglobin levels decreased <12 g/dL, rather than the conventional threshold of <10 g/dL.
Reductions of RBV dose due to anemia in patients who receive PEG-IFN and RBV are influenced by ITPA polymorphisms.12 Also, in patients who had received the triple therapy the RBV dose had to be reduced more in patients with CC than CA/AA genotypes during the first 12 weeks while they received telaprevir (52 ± 14% vs. 65 ± 21% of the target dose, P = 0.039). During the second 12 weeks off telaprevir, the RBV dose was somewhat greater in patients with CC than CA/AA genotypes (47 ± 24% vs. 43 ± 20%, P = 0.649). Thus, the total RBV dose during 24 weeks of therapy was comparable between patients with CC and CA/AA genotypes (51 ± 15% and 57 ± 18%, P = 0.724). Likewise, the total dose of PEG-IFN (87 ± 23% vs. 86 ± 20% of the target, P = 0.806), as well as that of telaprevir (87 ± 27% vs. 71 ± 36% of the target, P = 0.098), was no different between patients with CC and CA/AA genotypes. SVR was achieved comparably frequently in them (71% vs. 67%, P = 0.736).
Decreases in hemoglobin levels during the first 12 week were similar between the current triple therapy cohort and previous patients receiving PEG-IFN and RBV.12, 13 The conservative hemoglobin levels chosen for RBV dose reduction may be a possible confounding factor on the impact of ITPA variants in anemia, which would have been greater should the RBV dose not be reduced in patients with RBV-sensitive CC genotypes.
ITPA polymorphisms at rs1127354 were associated with RBV-induced anemia in Japanese patients, without involvement of those at rs7270107 reported in Caucasian and African-American patients.13 Thus, ITPA polymorphisms at rs1127354 would play a major role in protecting patients from RBV-induced anemia. CC/CA genotypes at rs1127354 occurs in 6% of the Caucasian population, much less often in the Oriental population, at 16%.25, 27 Although AC/CC genotypes at rs7270107 occurs in 13% of Caucasians, they do not exist in Orientals.11, 25 Obviously, different polymorphisms need to be examined in patients of distinct ethnicities when the influence on RBV-induced anemia is to be evaluated.
In confirmation of our previous report,28 the triple therapy achieved SVR more frequently in patients with CC than CT/TT genotypes of IL28 at rs12979860 (96% vs. 41%, P< 0.001). About two-thirds of studied patients accomplished SVR with the triple treatment, although one-fourth of them were nonresponders to previous IFN-based treatments; they are known to respond poorly to repeated treatments. This would lend further support to the efficacy of triple therapy being higher than treatment with pegylated IFN and RBV.
There are strong points in this study. First, ITPA polymorphisms influence RBV-induced anemia in the triple therapy. Second, polymorphisms at rs1127350, without involvement of those at rs7270107, protect against RBV-induced anemia. Third, the triple therapy can be applied with high efficacy by careful monitoring of hemoglobin and prompt modification of RBV dose. There are weak points in this study as well. First, it was a retrospective cohort study conducted in a small size of patients, especially those with CA/AA genotypes at rs1127350, and included null-responders to previous IFN-based therapies; the real impact of ITPA polymorphisms on RBV-induced anemia may have been obscured. Second, the study was conducted in Japanese patients, and the results may or may not be extended to patients of different ethnicities with distinct genetic backgrounds. Hopefully, the results presented herein will promote future studies in which the influence of the ITPA polymorphism on RBV-induced anemia will be pursued in larger scale and on patients of various ethnicities around the world.
Study Cohort.
This retrospective cohort study was performed in 61 patients with chronic hepatitis C who met the following inclusion and exclusion criteria. Inclusion criteria were: (1) diagnosed with chronic hepatitis C; (2) HCV-1 confirmed by sequence analysis in the NS5B region; (3) HCV RNA levels ≥5.0 log IU/mL determined by the COBAS TaqMan HCV test (Roche Diagnostics K.K. Tokyo, Japan); (4) Japanese aged from 20 to 65 years at the entry; and (5) body weight between ≥40 kg and ≤120 kg at the time of registration. Exclusion criteria were: (1) decompensated liver cirrhosis; (2) hepatitis B surface antigen in serum; (3) hepatocellular carcinoma or its history; (4) autoimmune hepatitis, alcoholic liver disease, hemochromatosis, or chronic liver disease other than chronic hepatitis C; (5) chronic renal disease or creatinine clearance ≤50 mL/min at the baseline; (6) hemoglobin ≤12 g/dL, neutrophil ≤1,500/mm3 or platelet ≤100,000/mm3 at baseline.
Of the 61 patients, 44 (72%) had received IFN-based treatment before. Relapse occurred in 29 (47%) and the remaining 15 (25%) did not respond (null-responders). All patients gave consent for analysis of SNPs in ITPA and interleukin 28 (IL28B) genes. The study was conducted in accordance with the ethical principles of the Declaration of Helsinki and was approved by the Ethics Committee of Toranomon Hospital. Written informed consent was obtained from each patient.
Triple Treatment with PEG-IFN-α-2b, RBV, and Telaprevir.
Telaprevir (MP-424; Mitsubishi Tanabe Pharma, Osaka, Japan), 750 mg, was administered 3 times a day at an 8-hour (q8) interval after each meal. Pegylated-IFN-α-2b (PEG-Intron, Schering Plough, Kenilworth, NJ) was injected subcutaneously at a median dose of 1.5 μg/kg (range: 1.32-1.71 μg/kg) once a week. RBV (Rebetol, Schering Plough) 200-600 mg was administered after breakfast and dinner. The RBV dose was adjusted by body weight: 600 mg for ≤60 kg; 800 mg for >60 kg ≈≤80 kg; and 1,000 mg for ≥80 kg. The triple therapy with PEG-IFN-α-2b, RBV, and telaprevir was continued for 12 weeks, and then switched to PEG-IFN-α-2b and RBV for an additional 12 weeks. It was withdrawn when hemoglobin levels decreased <8.5 g/dL. After the therapy was completed or discontinued, patients were followed for 24 weeks for SVR.
The RBV dose was cut by 200 mg in patients receiving 600 or 800 mg (by 400 mg in those receiving 1,000 mg) when hemoglobin decreased <12 g/dL, and by another 200 mg when it was below <10 g/dL. In addition, RBV was reduced by 200 mg in patients with hemoglobin <13 g/dL at baseline and those in whom it decreased by 1 g/dL to <13 g/dL within a week. PEG-IFN dose was reduced by one-half when the leukocyte count decreased <1,500/mm3, neutrophil count <750/mm3, or platelet count <80 x 103/mm3; PEG-IFN was withdrawn when they decreased <1,000/mm3, 500/mm3, or 50 x 103/mm3, respectively.
The triple therapy was withdrawn or stopped temporarily when hemoglobin decreased <8.5 g/dL. In patients in whom hemoglobin increased ≥8.5 g/dL within 2 weeks after the withdrawal, treatment was resumed with PEG-IFN and RBV 200 mg. A reduction of telaprevir (MP-424) dose was not permitted. It was discontinued when severe side effects appeared, whereas PEG-IFN and RBV were continued. Growth factors were not used for elevating hemoglobin levels.
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