Data from Isentress, Merck's HIV Integrase Inhibitor, in Patients Whose HIV is Controlled on a Lopinavir/Ritonavir-Based Therapy Presented at the 16th Conference on Retroviruses and Opportunistic Infections

MONTREAL--(BUSINESS WIRE)--Feb 9, 2009 - Merck & Co., Inc. (NYSE: MRK):

 

  • Switching from Lopinavir/Ritonavir-Based to ISENTRESS-Based Combination Antiretroviral Therapy Significantly Improved Total Cholesterol, Triglycerides, Non-HDL-Cholesterol at Week 12
  • Switching from Lopinavir/Ritonavir-Based to ISENTRESS-Based Combination Antiretroviral Therapy did not Demonstrate Non-Inferior Virologic Efficacy

Two Phase III studies (SWITCHMRK-1 and -2) evaluating the effect of switching patients whose HIV is controlled on a lopinavir/ritonavir-based regimen to a regimen containing <!-- cpurl -->Merck & Co<!-- /cpurl -->., Inc.'s HIV integrase inhibitor <!-- ppurl -->ISENTRESS<!-- /ppurl -->® (raltegravir) tablets showed that ISENTRESS significantly improved total cholesterol, triglycerides and non-HDL-cholesterol. Also, the study showed that ISENTRESS did not demonstrate non-inferior virologic efficacy at maintaining viral load suppression. As a result of the viral load findings in these trials, Merck discontinued these two studies.

Findings from the 24-week interim analyses of SWITCHMRK-1 and -2 were presented today at the 16th Conference on Retroviruses and Opportunistic Infections (CROI) in Montreal, Canada.

ISENTRESS is the first integrase inhibitor approved for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in treatment-experienced adult patients with evidence of viral replication with HIV-1 strains resistant to multiple antiretroviral agents. This indication is based on analyses of plasma HIV-1 RNA levels up through 48 weeks in two controlled studies of ISENTRESS. These studies were conducted in clinically advanced, three-class antiretroviral [nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs)] treatment-experienced adults. In these studies the use of other active agents with ISENTRESS is associated with a greater likelihood of treatment response. The safety and efficacy of ISENTRESS have not been established in treatment-naïve adult or pediatric patients.

As with all HIV treatment regimens, ISENTRESS should be used with other active antiviral agents.

Important safety information about ISENTRESS

ISENTRESS does not cure HIV or AIDS and does not prevent passing HIV to others. During the initial phase of treatment, patients responding to antiretroviral therapy may develop an inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium complex, cytomegalovirus, Pneumocystis jiroveci pneumonia, Mycobacterium tuberculosis or reactivation of varicella zoster virus), which may necessitate further evaluation and treatment.

Study results

In one study, Protocol 032 (also called SWITCHMRK-1), 81 percent of patients receiving a regimen with ISENTRESS maintained undetectable viral levels (less than 50 copies/mL) compared with 87 percent of patients receiving a regimen with lopinavir/ritonavir. In the second study, Protocol 033 (also called SWITCHMRK-2), the regimen with ISENTRESS maintained undetectable viral load levels in 88 percent of patients compared with 94 percent of patients receiving a regimen with lopinavir/ritonavir. In both studies, switching treatment to a regimen with ISENTRESS resulted in significantly greater decreases in total cholesterol, triglycerides and non-HDL-cholesterol (p<0.001) compared to continuing the lopinavir/ritonavir-based regimen.

Primary endpoints from the study include mean percent change in fasting lipids (total cholesterol, triglycerides, non-HDL and LDL) at Week 12, proportion of patients with viral load suppressed to undetectable levels (less than 50 copies/mL) at Week 24 and safety and tolerability at Week 24.

ISENTRESS did not demonstrate non-inferiority in maintaining viral load suppression

In regard to suppression of viral load, results at Week 24 showed that ISENTRESS did not demonstrate non-inferiority (one of the primary endpoints for both trials) as compared to lopinavir/ritonavir as measured by proportion of patients with undetectable viral levels. These results were based on an intent-to-treat analysis which assumes all study dropouts are virologic failures.

The viral load results are represented in the chart below:

HIV Viral Load (vRNA) Summary at Week 24

Number (%) of Patients

         
    Protocol 032   Protocol 033
  Lopinavir/Ritonavir   ISENTRESS   Lopinavir/Ritonavir   ISENTRESS
vRNA <50 copies>   152/174 (87.4)   139/172 (80.8)   167/178 (93.8)   154/175 (88.0)
vRNA <400 copies>   156/174 (89.7)   148/172 (86.0)   173/178 (97.2)   164/175 (93.7)
Based on post-hoc data collection, 84 percent (27 out of 32) of patients with confirmed virologic failure (viral levels greater than 50 copies/mL) in the group receiving ISENTRESS reported that their regimen at study entry was not their first antiretroviral regimen; and 66 percent (18 out of 27) of these patients reported a history of virologic failure on prior regimens.

“The observation that treatment with ISENTRESS did not achieve non-inferiority as measured by the proportion of patients with a viral load of less than 50 copies/mL as compared with lopinavir/ritonavir-based regimens underscores the complicated considerations involved in selecting the optimal treatment regimen for patients. Physicians should carefully evaluate all patient background information and previous treatment outcomes, including any change in viral load or tolerability concerns, when introducing a new therapy or considering a switch in treatment regimen,” said Joseph Eron, M.D., professor of medicine, Division of Infectious Diseases, University of North Carolina Chapel Hill School of Medicine.

Clinical adverse experiences of all severities were similar among patients treated with ISENTRESS as compared to those treated with the lopinavir/ritonavir-based regimen respectively (69.9 percent vs. 62.9 percent in Protocol 033; 62.6 percent vs. 60.9 percent in Protocol 032) and drug-related adverse events (13.1 percent vs. 19.7 percent in Protocol 033; 13.8 percent vs. 10.9 percent in Protocol 032).

Protocols 032 and 033 stopped

As a result of the viral load findings in these trials, Merck has stopped Protocols 032 and 033 and has notified the appropriate regulatory agencies and trial investigators for ISENTRESS about these data. At this time, only preliminary data are available for Protocols 032 and 033 and Merck is conducting thorough analyses of both studies to better understand the results.

“Merck remains committed to understanding appropriate utilization of ISENTRESS in a broad spectrum of HIV patients, and has alerted the appropriate regulatory agencies and trial investigators for ISENTRESS of these findings,” said Robin Isaacs, M.D., vice president, Clinical Research, Merck Research Laboratories. “We will conduct continued analyses of these findings as soon as complete results are available.”

ISENTRESS significantly improved total cholesterol, triglycerides, non-HDL cholesterol at Week 12

In regard to the co-primary endpoints of both studies, the data demonstrated that patients switched to ISENTRESS had significant decreases in total cholesterol, triglycerides and non-HDL cholesterol. There was no statistical difference in mean percent change from baseline in LDL. Results from the two studies are represented in the chart below.

Mean Percent Change from Baseline in Fasting Lipid Parameters at Week 12; p<0.001

         
    Protocol 032   Protocol 033
  Lopinavir/ Ritonavir

 

  ISENTRESS   Lopinavir/ Ritonavir

 

  ISENTRESS
    Base line mean

 

  Mean % change   Base line mean

 

  Mean % change   Base line mean

 

  Mean % change   Base line mean

 

  Mean % change
Total cholesterol (TC)   205   1   217   -13   211   1   214   -12
Triglycerides* TG)   164   4   190   -41   219   8   210   -43
Non-HDL cholesterol (non-HDL-C)   158   2   166   -15   164   3   168   -15
LDL-C   105   2   116   -2   104   1   104   4
HDL-C   47   1   49   -1   48   -3   46   -1
*Median value presented for triglycerides
Study Background

Protocol 032 and 033 studies are multi-center, double-blind, randomized, active-controlled non-inferiority studies to evaluate the safety, tolerability and efficacy of ISENTRESS in patients who are well controlled (viral load less than 50 copies/mL) on a stable lopinavir/ritonavir based regimen (400/100 mg twice daily) and were randomized to switch to ISENTRESS or continue on lopinavir/ritonavir. In these studies, 354 patients in Protocol 033 and 348 patients in Protocol 032 were randomized to remain on the lopinavir/ritonavir-based regimen or be switched to ISENTRESS 400 mg twice daily.

Patients enrolled in the study were required to be stable on the lopinavir/ritonavir-containing regimen, defined as having viral load suppressed to less than 50 copies/mL for at least three months, and were taking at least two nucleoside reverse transcriptase inhibitors (NRTIs) as part of their regimen. Because patients were enrolled in the study regardless of whether they had been on previous regimens prior to their lopinavir/ritonavir-based regimen, and regardless of the number of treatment failures previously experienced, the patient population in these studies had very diverse treatment experiences.

Additional important safety information about ISENTRESS

Due to rifampin's potent induction of uridine diphosphate glucoronosyltransferase (UGT) 1A1, the recommended dosage of ISENTRESS is 800 mg twice daily during coadministration with rifampin. Caution should be used when coadministering ISENTRESS with other strong inducers of UGT1A1 due to reduced plasma concentrations of ISENTRESS.

The most common adverse reactions of moderate to severe intensity (less than or equal to two percent) which occurred at a higher exposure adjusted rate compared to placebo are headache, nausea, asthenia and fatigue.

Creatine kinase elevations were observed in subjects who received ISENTRESS. Myopathy and rhabdomyolysis have been reported; however, the relationship of ISENTRESS to these events is not known. ISENTRESS should be used with caution in patients at increased risk of myopathy or rhabdomyolysis, such as patients receiving concomitant medication known to cause these conditions.

About ISENTRESS

ISENTRESS is the first medicine to be approved in a class of antiretroviral drugs called integrase inhibitors. ISENTRESS works by inhibiting the insertion of HIV-1 DNA into human DNA by the integrase enzyme. Inhibiting integrase from performing this essential function limits the ability of the virus to replicate and infect new cells. There are drugs in use that inhibit two other enzymes critical to the HIV-1 replication process – protease and reverse transcriptase – but ISENTRESS is the only drug approved that inhibits the integrase enzyme.

In October 2007, the U.S. Food and Drug Administration granted ISENTRESS accelerated approval and in January 2009 traditional approval for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in treatment-experienced adult patients with evidence of viral replication and HIV-1 strains resistant to multiple antiretroviral agents. ISENTRESS is a single 400 mg tablet taken twice daily without regard to food. During coadministration with rifampin, the recommended dosage of ISENTRESS is 800 mg twice daily with or without food. ISENTRESS does not require boosting with ritonavir.

Merck HIV research

Merck is committed to developing innovative therapies that offer advances in the treatment of infectious diseases – including HIV. Merck's efforts to develop investigational treatments for HIV and AIDS have been under way for more than 20 years and continue today. Merck began its HIV integrase inhibitor research in 1993 and was the first to demonstrate inhibition of HIV integrase in vitro and in vivo.

Prevalence of HIV and AIDS

In 2006, more than one million Americans were living with HIV and AIDS, and it is estimated that approximately more than 56,000 new cases of HIV and AIDS are diagnosed each year in the United States.

Worldwide, an estimated 33 million people are infected with HIV and AIDS, and more than two million new infections occurred in 2007.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck currently discovers, develops, manufactures and markets vaccines and medicines to address unmet medical needs. The Company devotes extensive efforts to increase access to medicines through far-reaching programs that not only donate Merck medicines but help deliver them to the people who need them. Merck also publishes unbiased health information as a not-for-profit service. For more information, visit www.merck.com.

Forward-looking statement

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements are based on management's current expectations and involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential or financial performance. No forward-looking statement can be guaranteed and actual results may differ materially from those projected. Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect Merck's business, particularly those mentioned in the risk factors and cautionary statements in Item 1A of Merck's Form 10-K for the year ended Dec. 31, 2007, and in any risk factors or cautionary statements contained in the Company's periodic reports on Form 10-Q or current reports on Form 8-K, which the Company incorporates by reference.

Prescribing information and patient prescribing information for ISENTRESS® is attached.

ISENTRESS® is a registered trademark of Merck & Co., Inc., Whitehouse Station, N.J., USA

HIGHLIGHTS OF PRESCRIBING INFORMATION

These highlights do not include all the information needed to use ISENTRESS safely and effectively. See full prescribing information for ISENTRESS.

ISENTRESS (raltegravir) Tablets

Initial U.S. Approval: 2007

RECENT MAJOR CHANGES

Indications And Usage (1) 01/2009

Dosage And Administration (2) 01/2009

Warnings And Precautions (5) 01/2009

INDICATIONS AND USAGE

ISENTRESS® is a human immunodeficiency virus integrase strand transfer inhibitor (HIV-1 INSTI) indicated:

 

  • In combination with other antiretroviral agents for the treatment of HIV-1 infection in treatment-experienced adult patients who have evidence of viral replication and HIV-1 strains resistant to multiple antiretroviral agents (1).

The safety and efficacy of ISENTRESS have not been established in treatment-naïve adult patients or pediatric patients (1).

DOSAGE AND ADMINISTRATION

 

  • 400 mg administered orally, twice daily with or without food (2).
  • During coadministration with rifampin, 800 mg twice daily (2).

DOSAGE FORMS AND STRENGTHS

Tablets: 400 mg (3).

CONTRAINDICATIONS

None

WARNINGS AND PRECAUTIONS

Monitor for Immune Reconstitution Syndrome (5.1).

ADVERSE REACTIONS

 

  • The most common adverse reactions of moderate to severe intensity ((>=)2%) which occurred at a higher exposure adjusted rate compared to placebo are headache, nausea, asthenia and fatigue (6.1).
  • Creatine kinase elevations were observed in subjects who received ISENTRESS. Myopathy and rhabdomyolysis have been reported; however, the relationship of ISENTRESS to these events is not known. Use with caution in patients at increased risk of myopathy or rhabdomyolysis, such as patients receiving concomitant medications known to cause these conditions (6.1).

To report SUSPECTED ADVERSE REACTIONS, contact Merck & Co., Inc. at 1-877-888-4231 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

USE IN SPECIFIC POPULATIONS

Pregnancy:

 

  • ISENTRESS should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Physicians are encouraged to register pregnant women exposed to ISENTRESS by calling 1-800-258-4263 so that Merck can monitor maternal and fetal outcomes (8.1).

Nursing Mothers:

 

  • Breast-feeding is not recommended while taking ISENTRESS (8.3).

See 17 for PATIENT COUNSELING INFORMATION and FDA-approved patient labeling.

Revised: 01/2009

FULL PRESCRIBING INFORMATION: CONTENTS*

1 INDICATIONS AND USAGE

2 DOSAGE AND ADMINISTRATION

3 DOSAGE FORMS AND STRENGTHS

4 CONTRAINDICATIONS

5 WARNINGS AND PRECAUTIONS

5.1 Immune Reconstitution Syndrome

5.2 Drug Interactions

6 ADVERSE REACTIONS

6.1 Clinical Trials Experience

6.2 Postmarketing Experience

7 DRUG INTERACTIONS

7.1 Effect of Raltegravir on the Pharmacokinetics of Other Agents

7.2 Effect of Other Agents on the Pharmacokinetics of Raltegravir

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

8.3 Nursing Mothers

8.4 Pediatric Use

8.5 Geriatric Use

8.6 Use in Patients with Hepatic Impairment

8.7 Use in Patients with Renal Impairment

10 OVERDOSAGE

11 DESCRIPTION

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

12.2 Pharmacodynamics

12.3 Pharmacokinetics

12.4 Microbiology

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

14 CLINICAL STUDIES

16 HOW SUPPLIED/STORAGE AND HANDLING

17 PATIENT COUNSELING INFORMATION

*Sections or subsections omitted from the Full Prescribing Information are not listed.

FULL PRESCRIBING INFORMATION

1 INDICATIONS AND USAGE

ISENTRESS1 in combination with other antiretroviral agents is indicated for the treatment of HIV-1 infection in treatment-experienced adult patients who have evidence of viral replication and HIV-1 strains resistant to multiple antiretroviral agents.

This indication is based on analyses of plasma HIV-1 RNA levels up through 48 weeks in two controlled studies of ISENTRESS. These studies were conducted in clinically advanced, 3-class antiretroviral (NNRTI, NRTI, PI) treatment-experienced adults.

The use of other active agents with ISENTRESS is associated with a greater likelihood of treatment response [see Clinical Studies (14)].

The safety and efficacy of ISENTRESS have not been established in treatment-naïve adult patients or pediatric patients.

2 DOSAGE AND ADMINISTRATION

For the treatment of patients with HIV-1 infection, the dosage of ISENTRESS is 400 mg administered orally, twice daily with or without food. During coadministration with rifampin, the recommended dosage of ISENTRESS is 800 mg twice daily with or without food.

3 DOSAGE FORMS AND STRENGTHS

400 mg pink, oval-shaped, film-coated tablets with "227" on one side.

4 CONTRAINDICATIONS

None

5 WARNINGS AND PRECAUTIONS

5.1 Immune Reconstitution Syndrome

During the initial phase of treatment, patients responding to antiretroviral therapy may develop an inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium complex, cytomegalovirus, Pneumocystis jiroveci pneumonia, Mycobacterium tuberculosis, or reactivation of varicella zoster virus), which may necessitate further evaluation and treatment.

5.2 Drug Interactions

Due to rifampin's potent induction of uridine diphosphate glucuronosyltransferase (UGT) 1A1, the recommended dosage of ISENTRESS is 800 mg twice daily during coadministration with rifampin. Caution should be used when coadministering ISENTRESS with other strong inducers of UGT1A1 due to reduced plasma concentrations of raltegravir [see Drug Interactions (7)].

6 ADVERSE REACTIONS

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Treatment-Experienced Studies

The safety assessment of ISENTRESS in treatment-experienced subjects is based on the pooled safety data from the randomized, double-blind, placebo-controlled trials, BENCHMRK 1 and BENCHMRK 2 (Protocols 018 and 019) in antiretroviral treatment-experienced HIV-1 infected adult subjects. A total of 462 subjects received the recommended dose of ISENTRESS 400 mg twice daily in combination with optimized background therapy (OBT) compared to 237 subjects taking placebo in combination with OBT. The median duration of therapy in these trials was 48 weeks for subjects receiving ISENTRESS and 38 weeks for subjects receiving placebo. The total exposure to ISENTRESS was 387 patient-years versus 156 patient-years on placebo. The rates of discontinuation due to adverse events were 2% in subjects receiving ISENTRESS and 3% in subjects receiving placebo.

Clinical adverse drug reactions (ADRs) were considered by investigators to be causally related to ISENTRESS + OBT or placebo + OBT. Clinical ADRs of moderate to severe intensity occurring in ‰¥2% of subjects treated with ISENTRESS and occurring at a higher exposure adjusted rate compared to placebo are presented in Table 1.

Table 1: Adverse Drug Reactions* of Moderate to Severe Intensity  Occurring in ‰¥2%

of Treatment-Experienced Adult Subjects Receiving ISENTRESS

and at a Higher Exposure Adjusted Rate Compared to Placebo

(48 Week Analysis, Exposure Adjusted Incidence Rates)

 

 
System Organ Class,
Adverse Reactions

 

Randomized Studies Protocol 018 and 019
ISENTRESS 400 mg Twice Daily + OBT

(n = 462)¡

 

Placebo + OBT (n = 237)¡

 

Rate per 100 Patient-Years Rate per 100 Patient-Years
Nervous System Disorders
Headache 3 1
Gastrointestinal Disorders
Nausea 2 1
General Disorders and Administration Site Conditions
Asthenia 2 1
Fatigue 2 1
*Includes adverse reactions at least possibly, probably, or definitely related to the drug.

 Intensities are defined as follows: Moderate (discomfort enough to cause interference with usual activity);
Severe (incapacitating with inability to work or do usual activity).

¡n=total number of subjects per treatment group.

 

Less Common Adverse Reactions

The following ADRs occurred in <2% of subjects receiving ISENTRESS + OBT. These events have been included because of either their seriousness, increased frequency on ISENTRESS compared with placebo or investigator's assessment of potential causal relationship.

Gastrointestinal Disorders: abdominal pain, gastritis

Hepatobiliary Disorders: hepatitis

Immune System Disorders: hypersensitivity

Infections and Infestations: genital herpes, herpes zoster

Nervous System Disorders: dizziness

Renal and Urinary Disorders: renal failure

Adverse Events

Regardless of Drug Relationship

Cancers were reported in treatment-experienced subjects who initiated ISENTRESS with OBT; several were recurrent. The types and rates of specific cancers were those expected in a highly immunodeficient population (many had CD4+ cell counts below 50 cells/mm3 and most had prior AIDS diagnoses). The cancers included Kaposi's sarcoma, lymphoma, squamous cell carcinoma, hepatocellular carcinoma and anal cancer. Most subjects had other risk factors for cancer including tobacco use, papillomavirus and active hepatitis B virus infection. It is unknown if these cancer diagnoses were related to ISENTRESS use.

Grade 2-4 creatine kinase laboratory abnormalities were observed in subjects treated with ISENTRESS (see Table 3). Myopathy and rhabdomyolysis have been reported; however, the relationship of ISENTRESS to these events is not known. Use with caution in patients at increased risk of myopathy or rhabdomyolysis, such as patients receiving concomitant medications known to cause these conditions.

Laboratory Abnormalities

The percentages of adult subjects treated with ISENTRESS 400 mg twice daily or placebo in Protocols 018 and 019 with selected Grade 2 to 4 laboratory abnormalities representing a worsening from baseline are presented in Table 2.

Table 2: Selected Grade 2 to 4 Laboratory Abnormalities Reported in
Treatment-Experienced Subjects (48 Week Analysis)

 

     
    Randomized Studies Protocol 018 and 019
Laboratory
Parameter
Preferred Term
(Unit)

 

Limit ISENTRESS
400 mg
Twice Daily
+ OBT
(N = 462)

 

Placebo
+
OBT
(N = 237)

 

Hematology
Absolute neutrophil count (103/ μL)

 

Grade 2 0.75 - 0.999 3% 5%
Grade 3 0.50 - 0.749 3% 3%
Grade 4 <0.50 1% <1%
Hemoglobin (gm/dL)
Grade 2 7.5 - 8.4 1% 3%
Grade 3 6.5 - 7.4 1% <1%
Grade 4 <6.5 <1% 0%
Platelet count (103/μL)
Grade 2 50 - 99.999 3% 5%
Grade 3 25 - 49.999 1% <1%
Grade 4 <25 1% <1%
Blood chemistry
Fasting (non-random) serum glucose test (mg/dL)
Grade 2 126 - 250 8% 5%
Grade 3 251 - 500 2% 1%
Grade 4 >500 0% 0%
Total serum bilirubin
Grade 2 1.6 - 2.5 x ULN 5% 3%
Grade 3 2.6 - 5.0 x ULN 2% 2%
Grade 4 >5.0 x ULN 1% 0%
Serum aspartate aminotransferase
Grade 2 2.6 - 5.0 x ULN 8% 6%
Grade 3 5.1 - 10.0 x ULN 3% 3%

Posted: February 2009

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