Top-Line Results of Boceprevir Phase II Study Showed High Rate of Sustained Response (SVR) in Genotype 1 Treatment-Naive Hepatitis C Patients
74 percent of patients achieved SVR 12 with 48-week boceprevir-based combination therapy
KENILWORTH, N.J., August 04, 2008 /PRNewswire-FirstCall/ -- Schering-Plough Corporation today reported top-line results from a planned interim analysis of a Phase II study of boceprevir, its investigational oral hepatitis C protease inhibitor. The analysis showed a high rate of sustained virologic response (SVR) in patients receiving boceprevir-based combination therapy in this study of 595 treatment-naive patients with chronic hepatitis C virus (HCV) genotype 1.
In a 48-week treatment regimen, the SVR rate at 12 weeks after the end of treatment (SVR 12) was 74 percent (ITT) in patients who received 4 weeks of PEGINTRON(TM) (peginterferon alfa-2b) and REBETOL(R) (ribavirin, USP) prior to the addition of boceprevir (800 mg TID) (P/R lead-in), compared to 38 percent for patients in the control group receiving 48-weeks of PEGINTRON and REBETOL alone.(1-3)
Patients in the study who received 48-weeks of boceprevir in combination with PEGINTRON and REBETOL from the beginning of treatment (no P/R lead-in) achieved 66 percent SVR 12.
In the two 28-week boceprevir arms of the study, SVR at 24 weeks after the end of treatment (SVR 24) was 56 percent and 55 percent for patients in the lead-in and no lead-in arms, respectively.
Importantly, for patients who received the PEGINTRON and REBETOL lead in and had rapid virologic response (RVR), defined as undetectable virus (HCV-RNA) in plasma after 4 weeks of boceprevir treatment, SVR (ITT) was 82 percent in the 28-week regimen and 92 percent in the 48 week regimen.
"These top-line results with boceprevir are very exciting, especially given that genotype 1 is the most common and hardest to treat form of hepatitis C," said Paul Kwo, M.D., associate professor of medicine and medical director, liver transplantation, Department of Medicine, Division of Gastroenterology/Hepatology, , Indianapolis, and lead investigator of the study. "Boceprevir was well tolerated by patients in this study, including those who received 48 weeks of boceprevir in the longer duration treatment arms."
Safety data from the study showed that the most common adverse events reported in the boceprevir arms were fatigue, anemia, nausea and headache. No increase in skin adverse events (rash or pruritus) beyond what was seen in the PEGINTRON and REBETOL control arm was observed. Treatment discontinuations due to adverse events were between 9 and 19 percent for patients in the boceprevir arms, compared to 8 percent for the control arm.
In the study, known as HCV SPRINT-1 (HCV Serine Protease Inhibitor Therapy-1), boceprevir (800 mg TID) was evaluated in three treatment regimens: 4 weeks of PEGINTRON (1.5 mcg/kg once weekly) and REBETOL (800-1400 mg daily based on patient weight) therapy followed by the addition of boceprevir to the combination for 24 or 44 weeks (totaling 28 or 48 weeks of treatment); boceprevir in combination with PEGINTRON and REBETOL at the doses described above for 28 or 48 weeks; and boceprevir in combination with PEGINTRON and low-dose REBETOL (400-1000 mg daily) for 48 weeks, compared to a control of PEGINTRON (1.5 mcg/kg once weekly) and REBETOL (800-1400 mg daily based on patient weight) alone for 48 weeks (an approved treatment regimen). The primary endpoint of the study is SVR after 24 weeks of follow up (SVR 24). This is an ongoing study and SVR 24 rates are not yet available for patients in the 48-week boceprevir arms or the 48-week control arm of the study.
Sustained Virologic Response (ITT)* Treatment Arm All patients No P/R Lead-in 28 Weeks 55% (59/107) P/R Lead-in 28 Weeks 56% (58/103) No P/R Lead-in 48 Weeks 66% (68/103) P/R Lead-in 48 Weeks 74% (76/103) P/R Control 48 Weeks 38% (39/104)
P/R Lead-in equals PEGINTRON and REBETOL for 4 weeks prior to the addition of boceprevir
P/R Control equals PEGINTRON and REBETOL alone for 48 weeks * SVR 12 for 48 week arms; SVR 24 for 28 week arms(1-3)
"These top-line results further validate this novel treatment paradigm and the design of our pivotal Phase III studies of boceprevir, one in treatment-naive patients and one in patients who had failed prior treatment, in which all patients will receive 4 weeks of PEGINTRON and REBETOL prior to the addition of boceprevir," said Thomas P. Koestler, Ph.D., executive vice president and president of Schering-Plough Research Institute. "Additionally, this strategy has the potential to reduce the likelihood of the development of resistance by identifying patients who are responders to interferon and ribavirin prior to their receiving a protease inhibitor."
The rationale for this novel treatment regimen is based on the fact that both PEGINTRON and REBETOL reach steady-state concentrations by week 4, so patients have the protease inhibitor added at a time when the backbone drug levels have been optimized. In addition, the patient's immune system will have been activated and primed by PEGINTRON at the time that boceprevir is added to the regimen. This approach may minimize the period of time when there is a "functional monotherapy" with a direct antiviral, potentially reducing the likelihood for the development of resistance.
The HCV SPRINT-1 study was conducted at sites across the United States, Canada and Europe. Overall, 77 percent of the 595 patients in the study were enrolled in the United States. African-Americans represent 16 percent of the patients enrolled and 7 percent of patients in the study are cirrhotic.
Results from the HCV SPRINT-1 study will be submitted for presentation at a major medical conference later this year.
About Boceprevir Phase III Studies
The boceprevir Phase III studies are expected to begin enrolling patients this summer. For more information about the Phase III study of boceprevir in treatment-naÃ¯ve patients, known as HCV SPRINT-2, and the Phase III study in patients who failed prior treatment, known as HCV RESPOND-2, please visit www.clinicaltrials.gov, search term boceprevir.
About Hepatitis C
Hepatitis C is a serious and potentially life-threatening disease. It is the most common blood-borne infection in America and Europe, and the most common form of liver disease, affecting nearly 5 million people in the United States, 5 million in Europe and some 200 million people worldwide. It is the leading cause of cirrhosis and liver cancer, and the number one reason for liver transplants in the United States and Europe.
In the United States, PEGINTRON is indicated for use alone or with ribavirin for the treatment of chronic hepatitis C in patients with compensated liver disease who have not been previously treated with interferon alpha and who are at least 18 years of age.
Important Safety Information Regarding U.S. Labeling for PEGINTRON and REBETOL
Alpha interferons, including PEGINTRON and INTRON(R) A, may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Patients should be monitored closely with periodic clinical and laboratory evaluations. Patients with persistently severe or worsening signs or symptoms of these conditions should be withdrawn from therapy. In many, but not all cases, these disorders resolve after stopping PEGINTRON and/or INTRON A therapy.
Use with Ribavirin: Ribavirin may cause birth defects and/or death of the unborn child. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients. Ribavirin causes hemolytic anemia. The anemia associated with REBETOL therapy may result in a worsening of cardiac disease. Ribavirin is genotoxic and mutagenic and should be considered a potential carcinogen.
PEGINTRON is contraindicated in patients with hypersensitivity to PEGINTRON or any other component of the product, autoimmune hepatitis, and hepatic decompensation (Child-Pugh score greater than 6 [class B and C]) in cirrhotic CHC patients before or during treatment. INTRON A (Interferon alfa-2b, recombinant) for Injection is contraindicated in patients with hypersensitivity to INTRON A or any component of the product, autoimmune hepatitis, and decompensated liver disease. PEGINTRON or INTRON A in combination with REBETOL therapy is additionally contraindicated in patients with hypersensitivity to ribavirin or any other component of the product, women who are pregnant, men whose female partners are pregnant, patients with hemoglobinopathies (e.g., thalassemia major, sickle-cell anemia), and patients with creatinine clearance less than 50 mL/min.
REBETOL therapy should not be started until a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients during therapy and 6 months post-treatment. Patients should use at least two effective forms of contraception and have monthly pregnancy tests during therapy and for 6 months after completion of therapy. A Ribavirin Pregnancy Registry has been established to monitor maternal-fetal outcomes of pregnancies in female patients and female partners of male patients exposed to ribavirin during treatment, and for 6 months following cessation of treatment. Physicians and patients are encouraged to report such cases by calling 1-800-593-2214.
Incidence of Adverse Events
There are no new adverse events specific to PEGINTRON as compared to INTRON A; however, the incidence of some (e.g., injection site reactions, fever, rigors, nausea) were higher. The most common adverse events associated with PEGINTRON were "flu-like" symptoms, occurring in approximately 50% of patients, which may decrease in severity as treatment continues. Application site disorders were common (47%), but all were mild (44%) or moderate (4%) and no patient discontinued, and included injection site inflammation and reaction (i.e., bruise, itchiness, irritation). Injection site pain was reported in 2% of patients receiving PEGINTRON. Alopecia (thinning of the hair) is also often associated with alpha interferons including PEGINTRON.
Psychiatric adverse events, which include insomnia, were common (57%) with PEGINTRON but similar to INTRON A (58%). Depression was most common at 29%. Suicidal behavior including ideation, suicidal attempts, and completed suicides occurred in 1% of patients during or shortly after completing treatment with PEGINTRON.
The following serious or clinically significant adverse events have been reported at a frequency less than 1% with PEGINTRON or interferon alpha: Severe decreases in neutrophil or platelet counts, hypothyroidism, hyperglycemia, hypotension, arrhythmia, ulcerative and hemorrhagic colitis, development or exacerbation of autoimmune disorders including thyroiditis, RA, systemic lupus erythematosus, psoriasis, pulmonary disorders (dyspnea, pulmonary infiltrates, pneumonitis and pneumonia, some resulting in patient deaths), urticaria, angioedema, bronchoconstriction, anaphylaxis, retinal hemorrhages, and cotton wool spots.
In the PEGINTRON/REBETOL combination trial, the incidence of serious adverse events was 17% in the PEGINTRON/REBETOL groups compared to 14% in the INTRON A/ REBETOL group. The incidence of severe adverse events in the PEGINTRON/REBETOL combination therapy trial was 23% in the INTRON A/REBETOL group and 31-34% in the PEGINTRON/REBETOL groups. Dose reductions due to adverse reactions occurred in 42% of patients receiving PEGINTRON (1.5 mcg/kg)/REBETOL and in 34% of those receiving INTRON A/REBETOL.
In a study with weight-based ribavirin, there was a higher rate of anemia among patients in the weight-based dosing group (29%) compared to the flat-dosing group (19%). The majority of these cases were mild and responded to dose reductions. Serious adverse events were similar between the two groups (12%), and discontinuations for adverse events (15% in weight-based dosing and 14% in flat dosing) were also similar. Dose modifications due to adverse events occurred more frequently in the weight-based dosing group (29%) compared to the flat-dosing (23%) group.
Additional Safety Information
Relapse of drug addiction/overdose has occurred in patients on PEGINTRON therapy. Aggressive behavior sometimes directed towards others has occurred in patients with and without a previous psychiatric disorder during PEGINTRON and/or INTRON A treatment and follow-up. If patients develop psychiatric problems, including clinical depression, it is recommended that patients be carefully monitored during treatment and in the 6-month follow-up period. If psychiatric symptoms persist or worsen, or suicidal ideation or aggressive behavior towards others is identified, it is recommended that treatment with PEGINTRON and/or INTRON A be discontinued, and the patient be carefully followed with psychiatric intervention, as appropriate. Cases of encephalopathy have been observed in some patients, usually elderly, treated with higher doses of PEGINTRON and/or INTRON A. Ischemic and hemorrhagic cerebrovascular events have been observed in patients treated with interferon alpha therapies, including PEGINTRON and INTRON A. Dental and periodontal disorders have been reported in patients receiving PEGINTRON or INTRON A in combination with REBETOL therapy.
Schering-Plough is an innovation-driven, science-centered global health care company. Through its own biopharmaceutical research and collaborations with partners, Schering-Plough creates therapies that help save and improve lives around the world. The company applies its research-and-development platform to human prescription and consumer products as well as to animal health products. Schering-Plough's vision is to "Earn Trust, Every Day" with the doctors, patients, customers and other stakeholders served by its colleagues around the world.
SCHERING-PLOUGH DISCLOSURE NOTICE: The information in this press release includes certain "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including statements relating to the company's clinical development plans and the potential for boceprevir. Forward-looking statements relate to expectations or forecasts of future events. Schering-Plough does not assume the obligation to update any forward-looking statement. Many factors could cause actual results to differ materially from Schering-Plough's forward-looking statements, including market forces, economic factors, product availability, patent and other intellectual property protection, current and future branded, generic or over-the-counter competition, the regulatory process, and any developments following regulatory approval, among other uncertainties. For further details about these and other factors that may impact the forward-looking statements, see Schering-Plough's Securities and Exchange Commission filings, including Part II, Item 1A, "Risk Factors" in company's second quarter 2008 10-Q.
(1) SVR, the protocol specified primary efficacy endpoint, is defined as achievement of undetectable HCV-RNA at 24 weeks after the end of treatment. Per protocol, if a patient does not have a 24-week post-treatment assessment, the patient's 12-week post-treatment assessment will be utilized.
(2) SVR 12 is defined as undetectable HCV-RNA in plasma at 12 weeks after the end of treatment. The protocol specified primary efficacy endpoint of the HCV SPRINT-1 study is SVR as defined above.
(3) Intention-To-Treat (ITT) analysis includes any patient who has taken at least one dose of any study drug.
Posted: August 2008