Triangle drops NNRTI and puts PI on hold

Keith Alcorn
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This article is more than 23 years old.

Triangle Pharmaceuticals has announced that development of the non-nucleoside reverse transcriptase inhibitor emivirine (Coactinon) is to be halted following an interim analysis of a trial comparing emivirine with abacavir (study MKC-401), in which all participants also received d4T and FTC. Viral load suppression was significantly poorer in the emivirine arm compared to the abacavir arm.

Emivirine is one of five agents under development by Triangle, but its progress has been slow and results from earlier phase III studies had not been particularly strong. In an unusual move, the FDA asked Triangle to design a new study in late 1999 that would combine test emivirine with another of the company’s unlicensed agents, FTC.

Triangle also announced yesterday that it is moving forward with plans to submit a new drug application to the Food and Drug Administration for FTC (emtricitabine) in the fourth quarter of 2002. FTC (Coviracil) is a once daily nucleoside analogue with a similar resistance pattern to 3TC, and is also active against hepatitis B. Abbott Laboratories will handle marketing of Coviracil worldwide.

Glossary

nucleoside

A precursor to a building block of DNA or RNA. Nucleosides must be chemically changed into nucleotides before they can be used to make DNA or RNA. 

Food and Drug Administration (FDA)

Regulatory agency that evaluates and approves medicines and medical devices for safety and efficacy in the United States. The FDA regulates over-the-counter and prescription drugs, including generic drugs. The European Medicines Agency performs a similar role in the European Union.

phase III

The third and most definitive stage in the clinical evaluation of a new drug or intervention, typically a randomised control trial with the new intervention compared to an existing therapy or a placebo, in large numbers of participants (typically hundreds or thousands). Trial results are used to evaluate the overall risks and benefits of the drug and provide the information needed for regulatory approval.

reverse transcriptase

A retroviral enzyme which converts genetic material from RNA into DNA, an essential step in the lifecycle of HIV. Several classes of anti-HIV drugs interfere with this stage of HIV’s life cycle: nucleoside reverse transcriptase inhibitors and nucleotide reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). 

metabolism

The physical and chemical reactions that produce energy for the body. Metabolism also refers to the breakdown of drugs or other substances within the body, which may occur during digestion or elimination.

Triangle’s decision to drop emivirine is largely driven by a cash shortage; it has taken the company longer than expected to bring one of its agents to market. Last October the company shed a third of its staff and

The company also admitted that it had no further plans to develop mozenavir, a once daily protease inhibitor, despite showing comparability with indinavir in a Phase III study reported at last summer’s International AIDS Society conference in Buenos Aires. Mozenavir’s future is uncertain; despite promising results, the drug cannot be boosted with ritonavir, does not appear to carry a reduced risk of metabolic disturbances and is not active against virus already resistant to ritonavir or indinavir.

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