April 10, 2008
Incyte Pharmaceuticals recently announced their decision to halt development of their experimental HIV drug, INCB9471. INCB9471 is a type of HIV drug called a CCR5 antagonist, which looked promising in early clinical studies. The company claims it is seeking another company to continue its development.
Incyte's press release claims the decision not to move forward with INCB9471 was to allow them to focus on another drug for treating a kind of cancer, called a JAK inhibitor. While acknowledging the financial pressures faced by small biotech companies developing new drugs, Project Inform is greatly disappointed by this decision to abandon a promising new drug.
Incyte makes no mention of the widely reported slow sales of Pfizer's first-in-class CCR5 drug, Selzentry (maraviroc), but it is difficult not to see this setback in this light. It is a mistake for Incyte, or other pharmaceutical company, to make long-range decisions based, even in part, by the short-term struggles of one drug.
The slower than expected sales of Selzentry are likely due to three factors, none of which are necessarily long-term. One important issue is problems with the Trofile test -- a blood test that determines tropism, or whether a CCR5 drug is likely to work. The Trofile assay is very expensive, takes a minimum of three weeks for results, and has shown a mixed record at predicting clinical success with Selzentry. Several other tests and ways to determine tropism are being studied. Monogram, the company that does the Trofile test, is busy developing a second generation test, which is hoped to be more accurate if not less costly.
The second factor is that Selzentry was approved very close to another new drug, Isentress (raltegravir). Isentress showed remarkable results throughout clinical studies, and does not require an expensive, time-consuming blood test. While it is fair to debate the relative merits of these two drugs, the truth remains that Isentress enjoys a better perception by doctors, researchers and people with HIV.
The last factor is the lack of clarity on how to best use CCR5 drugs. Selzentry was first studied in, and approved for, people with extensive HIV treatment experience. The results from the experienced studies were quite good, but close to half the people who enrolled didn't have the necessary R5-only result from the Trofile test. It is has also been studied in, but not approved for, people taking HIV drugs for the first time. People in earlier stages of HIV disease will more likely have R5-only HIV, but the data on Selzentry in this group are mixed. Cheaper and more accurate ways of determining tropism, along with more research and real world use of Selzentry, should help resolve these issues.
It would be a shame to see a few months of slow sales on one drug sour the industry, or even a single company on a promising class of HIV drugs. While the last couple of years have experienced a bumper crop of important new drugs, the next few look quite thin. We do not want to see history repeated like that of another class of HIV drugs called NNRTIs. It was over 10 years between the development of the first drugs to the availability of the next generation drugs.
Project Inform recognizes that HIV drug development is unlikely to continue at the pace it has maintained for the past 20 years. We also recognize a real need for new and better drugs, particularly those from new classes, that overcome resistance to existing drugs and are more tolerable to take. HIV treatment is a long-term endeavor. We encourage companies to take the long view as well, and continue to invest in promising new HIV treatments.
All hope is not lost for INCB9471. As mentioned, the company has said that they want to find a company to continue the drug's development. Its early research held promise. Project Inform hopes a company will see the promise of INBC9471, and invest in further researching and developing this drug.