Good News for People in Salvage Therapy: Merck to start its expanded access program for its integrase inhibitor MRK 518

I am very excited about this expanded access of Merck’s integrase inhibitor, MRK 518.

I have been taking it for 3 months now with the new protease (Prezista) and have been able to reach undetectable viral load for the first time in 23 years. My CD4 cells have more than doubled from 180 to 440 cells/ml

The response to MRK 518 seems to be faster than most drugs in the past. In a naive study presented this week in Toronto that compared MRK 518 plus Truvada with Sustiva+Truvada, it was seen that MRK 518 can drive viral load down faster than Sustiva, although the Sustiva arm eventually matched the MRK 518 arm at week 24.

So far, no significant side effects have been observed besides an increased in flatulence in some patients.

MRK 518 is taken in one pill twice a day without Norvir ( no need for Norvir boosting is welcomed by many of us!). It seems that it does not have problematic interactions with most drugs since it is not metabolized in the P450 cytochrome in the liver.

I think MRK 518 will be an excellent drug in combination with Prezista and/or Fuzeon for those of us who have run out of options. It may present the first chance for many of us to have undetectable viral load.


Expanded Access Program for MK-0518, an Investigational HIV Integrase Inhibitor, Established for Patients with Limited Available Treatment Options

Worldwide Access Program Will Be Conducted Along With Phase III Studies

TORONTO, Aug. 17, 2006 — A worldwide expanded access program for HIV/AIDS patients with limited or no treatment options was announced today by Merck & Co., Inc., Whitehouse Station, N.J., U.S.A., with respect to its investigational HIV integrase inhibitor, MK-0518, now in Phase III development. Program enrollment will begin in the next few months, pending regulatory review and approvals.

“Making MK-0518 available to those who would like access to this investigational drug but who are unable to participate in the clinical studies underscores our commitment to patients,” said Dr. Peter S. Kim, president, Merck Research Laboratories (MRL).

MK-0518 belongs to a new class of investigational antiretroviral therapy (ART) agents called integrase inhibitors that inhibit the insertion of the HIV viral DNA into human DNA. Integrase is one of three HIV enzymes – reverse transcriptase, protease and integrase – required by the virus to reproduce. Drugs are available that inhibit the functions of the protease and reverse transcriptase enzymes but, to date, there are no approved drugs that target the integration stage of the HIV-1 lifecycle.

Expanded access

“The MK-0518 program is another example of Merck’s dedication to people living with HIV/AIDS around the world,” commented Dr. Randi Leavitt, senior director, Infectious Diseases – Clinical Research, MRL and lead coordinator of the expanded access program. “This makes the third expanded access program that Merck has initiated. In mid and late 1990, the Company implemented expanded access programs for two other investigational drugs for treatment of HIV,” Dr. Leavitt explained.

Expanded access is a mechanism supported by regulatory agencies for getting investigational treatment to patients who have a life threatening disease and who cannot be satisfactorily treated with an alternative therapy or available drug. Expanded access programs are not required by regulatory agencies. These
programs are initiated and supported by drug manufacturers in recognition of the promise an unapproved drug may hold for patients facing a life-threatening disease.

MK-0518 expanded access study design

The expanded access program with MK-0518 is a non-comparative, multi-center, open-label, voluntary treatment use study. Investigators will follow patients according to standard of care. The study will continue until approximately three months after MK-0518 has been launched in the local market.

To be eligible to participate, patients must have documented HIV-1 infection, be at least 16 years old, have limited or no treatment options available to them due to resistance or intolerance to multiple anti-retroviral regimens, are not achieving adequate virologic suppression on current regimen and be at risk of clinical or immunologic progression, and be clinically stable. Patients are excluded from the study if they have received MK-0518 in a clinical trial, require any medications prohibited by the protocol, have acute hepatitis due to any cause or clinically significant chronic liver disease, have a condition which the investigator deems will interfere with adherence and safety, or are pregnant.

Patients will receive open-label MK-0518 400 mg twice daily, in addition to optimized background therapy (OBT). Investigators will select the OBT based on the patient’s prior treatment history and anti-retroviral resistance testing. OBT will not be provided by Merck. Safety and tolerability of MK-0518 will be monitored.

The program will be managed by a clinical research organization (CRO). The CRO will collect all case report information including serious adverse events and drug-related adverse events that result in Grade 3 or above laboratory toxicity, leading to treatment interruption or discontinuation. No efficacy data will be collected.

About Merck’s HIV/AIDS research program

Merck’s HIV clinical research program began in 1985. Merck scientists were among the first to discover and develop medicines for the treatment of HIV/AIDS. In 1996, Merck introduced a protease inhibitor, which was followed by the introduction in 1999 of a non-nucleoside reverse transcriptase inhibitor (NNRTI).

In addition to MK-0518, Merck is focused on developing new treatments for millions of individuals who are already infected with HIV, as well as on preventing HIV transmission through the development of a vaccine. Merck also licensed a compound to the International Partnership for Microbicides (IPM) for development as a possible means of preventing HIV infection in women.

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