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AIDS Treatment News
Protease Inhibitors: Merck Plans Larger Trials, Expanded
John S. James
March 24, 1995
AIDS TREATMENT NEWS #219, March 24, 1995

Merck and Co. has devoted extraordinary resources and taken the lead in overcoming production problems of the current generation of protease inhibitors. In mid March it announced that its comparative trial and open-label protocol for persons with a CD4 (T-helper count) under 50 -- expected to start in mid 1995 -- could be expanded from 150 to over 1400 by the end of 1995. Merck also updated the community on its plans for large trials in other groups of patients.

The following phase III studies are currently planned: * 780 AZT-naive patients, with CD4 counts from 50 to 500, will be randomized to MK-639 (the current name of Merck protease inhibitor, formerly called L-735,524), AZT, or the combination. This one-year trial will look for changes in viral load and CD4 count. Screening and enrollment have begun in the U.S., Canada, and Europe.

* 540 AZT-experienced patients with CD4 counts from 50 to 500 will be randomized to MK-639, d4T, or the combination. This one-year trial will begin in May in the U.S. and Europe.

* In Brazil, 750 AZT-naive patients, with CD4 count from 50 - 250, will be randomized to MK-639, AZT, or the combination. This study will look for clinical endpoints, but will analyze CD4 counts after six months. This study is planned to begin in March 1995.

* 90 AZT-experienced patients (with CD4 count between 50 and 400) will be randomized to MK-639, AZT plus 3TC, or the triple combination. Enrollment will begin in April in the U.S.

* For those with CD4 count under 50, 300 patients will be randomized to MK-639, AZT plus 3TC, or the triple combination. Those for whom AZT or 3TC would be medically inappropriate will be assigned to receive open-label MK-639. After the comparative trial is enrolled, the open-label arm will be expanded to allow at least 1400 patients, by the end of 1995. This trial will start enrollment in June.

* Another large trial is planned for AZT-experienced patients, starting in late 1995. The treatment arms will be determined based on results of earlier trials.

Assuming all goes well, Merck plans to file for accelerated approval for MK-639. The company currently has no other AIDS drugs in development.

For information on enrolling in trials of MK-639, call 800/379-1332, 8 a.m. to 7 p.m. Eastern time.

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