Daniel M. Keller, PhD
April 6, 2011 (Berlin, Germany) — Telaprevir added to standard pegylated interferon alfa-2a/ribavirin (peg-IFN/RBV) therapy for hepatitis C virus (HCV) infection was superior to retreatment with peg-IFN/RBV plus placebo in patients for whom standard therapy had failed in the past, researchers announced here at the European Association for the Study of the Liver (EASL) 46th Annual Meeting.
The safety and tolerability of adding telaprevir were similar to results seen in previous trials. Adverse events leading to permanent discontinuation of the drugs consisted mainly of anemia and rash, and were more prevalent in the telaprevir groups than in the control group.
Standard combination therapy with peg-IFN/RBV fails in approximately 60% of patients with HCV genotype 1, which is one of the more difficult genotypes to eradicate, noted Stefan Zeuzem, MD, chief of the Department of Medicine and professor of medicine at the Johann Wolfgang Goethe University Hospital in Frankfurt, Germany, who presented the study results.
The aim of the Re-Treatment of Patients With Telaprevir-Based Regimen to Optimize Outcomes (REALIZE) trial was to test the addition of telaprevir, a new small-molecule HCV protease inhibitor, to peg-IFN/RBV in 662 patients with HCV genotype 1 for whom peg-IFN/RBV had previously failed to produce sufficient and sustained viral suppression.
The primary objective of this pivotal phase 3 international, multicenter, double-blind, placebo-controlled trial was to compare the proportion of patients achieving a sustained virologic response (SVR) with telaprevir plus peg-IFN/RBV and the proportion achieving an SVR with placebo plus peg-IFN/RBV. All SVRs were below 25 IU HCV RNA (undetectable level).
Patients were divided into 3 categories: null responders did not show at least a 2 log10 drop in serum HCV RNA at week 12 of previous standard therapy; partial responders experienced at least a 2 log10 drop at week 12 of previous therapy but still had detectable HCV RNA in the blood at week 24; and relapsers achieved viral levels below the limit of detection at 42 weeks but then had a recurrence of detectable virus.
The groups were well matched at baseline. Approximately 70% were men, median age was approximately 50 years, 93% were white, HCV RNA was above 800,000 IU/mL in 86% to 89%, and almost 60% were in the advanced stages of disease with bridging fibrosis or cirrhosis (26%). About half were infected with genotype 1a and about half with genotype 1b. About 30% were previous nonresponders, 20% were partial responders, and 50% were previous relapsers.
Patients were randomly assigned to 1 of 3 treatment groups: 266 patients received telaprevir + peg-IFN/RBV for 12 weeks, then placebo + peg-IFN/RBV for 4 weeks (T12/PR48); 264 patients received a lead-in of placebo + peg-IFN/RBV for 4 weeks, then telaprevir + peg-IFN/RBV for 12 weeks (lead-in T12/PR48); and 132 patients received placebo + peg-IFN/RBV for 16 weeks (placebo/PR48).
In these 3 groups, drug doses were as follows: telaprevir 750 mg every 8 hours; peg-IFN 180 µg/week; and RBV 1000 to 1200 mg/day. The groups were followed-up and assessed for SVR at week 72. The primary statistical calculations were on previous relapsers and on previous nonresponders (a combination of previous partial responders and null responders).
Dr. Zeuzem reported that among previous relapsers, 83% to 88% achieved an SVR when treated with telaprevir plus peg-IFN/RBV. Less than 10% of them relapsed by week 72. In contrast, only 41% of previous nonresponders achieved an SVR with telaprevir, but this figure was still a 4-fold increase over the proportion with an SVR when retreated with peg-IFN/RBV and placebo. Overall, about 35% of patients in the 2 telaprevir groups failed to achieve an SVR; those failures occurred mainly among previous partial and previous null responders.
Addition of Telaprevir to Peg-IFN/RBV Enhances SVR Rates
Patient Group T12/PR48, % (n/N) Lead-in T12/PR48, % (n/N) Placebo/PR48, % (n/N)
Previous Relapsers
SVRa 83 (121/145)c 88 (124/141)c 24 (16/68)
Relapseb 7 (10/135) 7 (9/138) 65 (30/46)
Previous Nonresponders
SVRa 41 (50/121)c 41 (51/123)c 9 (6/64)
Relapseb 23 (16/69) 25 (18/72) 33 (3/9)
a SVR assessed 24 weeks after planned treatment completion
b Relapse: detectable virus at week 72 in patients with undetectable HCV RNA at end of assigned treatment
c P < .001, comparison vs placebo/PR48
"The SVR rates tended to be higher in genotype 1b–infected patients, in particular in prior partial responders and prior null responders," Dr. Zeuzem reported. "The lead-in phase [group] showed numerically slightly higher [SVR] rates in the prior relapsers and the prior nonresponders, but there was an opposite trend for the prior partial responders."
When the data were analyzed by the degree of baseline fibrosis, all subgroups of patients responded better to telaprevir than to peg-IFN/RBV plus placebo. For example, among previous relapsers, 86%, 85%, and 84% achieved an SVR with telaprevir if they had no fibrosis, bridging fibrosis, or cirrhosis, respectively, compared with 32%, 13%, and 13%, respectively, with peg-IFN/RBV plus placebo. The addition of telaprevir added little or no benefit over peg-IFN/RBV alone for previous partial or null responders with cirrhosis.
Dr. Zeuzem noted that adverse events, which occurred at least 10% more frequently in the telaprevir groups than in the placebo group, were fatigue, pruritis, rash, anemia, nausea, diarrhea, and anorectal symptoms (described as pruritis, discomfort, or hemorrhoids).
The majority of adverse effects were grade 1 or 2, with some grade 3 rash in the pooled telaprevir groups. Rash was primarily eczematous, which resolved when therapy ended. Anemia was managed with RBV dose reduction when necessary, which occurred in 25% of the telaprevir-treated patients. Per protocol, erythropoiesis-stimulating agents were not permitted. In the telaprevir groups, 11% to 15% discontinued treatment because of adverse events; in the placebo group, 3% did.
Dr. Zeuzem concluded that "telaprevir/peg-interferon-ribavirin triple therapy was clearly superior to the standard peg-interferon/ribavirin treatment alone" in all 3 treatment-experienced populations."
He said a 4-week lead-in phase with peg-IFN/RBV did not reduce virologic failure or relapse rates and did not improve SVR rates. He noted that the safety of telaprevir was similar to that observed in previous studies. Adverse events, mainly anemia and rash, led to permanent discontinuation of study drugs more frequently in the telaprevir groups than in the control group.
Mark Thursz, MD, professor of hepatology at Imperial College, London, United Kingdom, and vice secretary of EASL, said: "I think these are very responsible conclusions . . . and I feel that the data that are coming out on this particularly difficult-to-treat group of patients — those who had previous treatment and failed — these are really exciting results. Overall, something like 60% of patients were successfully treated [and] reached an SVR in the REALIZE trial." He added that "partial responders [did] so-so; null responders, not so good. This is disappointing but not entirely surprising. They are particularly difficult groups to treat."
Dr. Thursz, who was not involved in the REALIZE trial, said that for patients for whom previous therapy has failed, "now we have treatment options to offer them, assuming that the commissioning authorities will pay for [the drugs] for those who don't pay for their own therapy."
In response to a question from the audience about the rashes and the possibility of Stevens–Johnson syndrome, Dr. Zeuzem said that of the several thousand people exposed to telaprevir, "to the very best of my knowledge, there is only 1 case of Stevens–Johnson syndrome described, but this case occurred after telaprevir was already discontinued, so a causal relationship cannot be justified from this single case. But I know that this single case has made many people very nervous."
Although anemia was more frequent in the telaprevir groups, "we have learned to manage anemia in this group of patients," Dr. Thursz said. "Most patients can tolerate more anemia than the pharmaceutical companies can."
Telaprevir is being developed by Vertex Pharmaceuticals. The US Food and Drug Administration has granted the drug priority review, which is expected on May 23.
Dr. Zeuzem reports relationships with Abbott, Achillion, Anadys, BMS, Gilead, iTherX, Merck, Novartis, Pfizer, Pharmasset, Roche, Santaris, Tibotec, and Vertex. Dr. Thursz has disclosed no relevant financial relationships.
European Association for the Study of the Liver (EASL) 46th Annual Meeting: Opening session. Presented March 30, 2011.
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