Glaxo to test rival's protease inhibitor, re-engineered to last longer

Keith Alcorn
Published: 02 June 2009

GlaxoSmithKline announced today that it has signed a development deal with Concert Pharmaceuticals for a new protease inhibitor, engineered to avoid the need for any sort of boosting agent.

CTP-518 is a modified form of the HIV protease inhibitor atazanavir in which key hydrogen atoms have been replaced by deuterium, a heavier relative of hydrogen. The drug’s developers believe that using deuterium will slow the rate at which the drug is eliminated from the body, thus achieving higher trough levels and potentially eliminating the need for boosting with ritonavir or another agent.

The advantage of dispensing with a boosting agent is that the product will cost less to use, and without ritonavir boosting, may carry a lower risk of triglyceride elevation.

Even though atazanavir, the best selling protease inhibitor in the US, is owned by Bristol Myers Squibb and marketed as Reyataz, Concert Pharmaceuticals has been granted a patent on its version of the drug. Concert Pharmaceuticals has also patented a deuterated version of darunavir, another protease inhibitor that must be boosted with ritonavir.

The drug will enter phase I studies shortly and GlaxoSmithKline has the option of subsequent commercialisation. Deuterated agents may not have the same toxicological and pharmacological data requirements as completely new agents, allowing developers to carry out studies for registration more quickly, according to a recent review in Drug Development and Discovery.