Friday, August 16, 2013

Genome Liberty: Predicting Your Drug Response Using Genomics

Susan Young, at MIT Technology Review, describes how a start up is developing a genetic test to predict your personal response to drugs:
Consumers who get the Genome Liberty drug response test would send a sample of saliva to the company’s lab. The company scans the genome for DNA variations in 11 liver enzyme genes, which are a subset of the dozens of genes encoding enzymes for drug metabolism. Enzymes in the liver process drugs and can either deactivate or activate drugs, depending on the compound. Different people carry different versions or amounts of many of these enzymes, which can affect how they respond to drugs. Some patients may process a drug more quickly, more slowly, or perhaps not at all.
Genome Liberty says that variants in those 11 enzymes can affect the activity of nearly 80 drugs in the body. 
Tests like these are nice, simple, and possibly very inexpensive approaches to help prescribe drugs.  I suspect Genome Liberty is basing their technology on something straightforward like a multiplex PCR to amplify relevant sites withing each enzyme's gene, followed by pooling of samples from many individuals and some basic sequencing.  The cost of producing the data on each patient/customer would be a fraction of their $99 price target, leaving a nice profit margin for Genome Liberty.

Now while spending $99 may not be cost-efficient to optimize a dose of Prilosec, an antacid which can cost about 42 cents per day, if you have a prescription for something like Abilify, an anti-depressant that can cost thousands of dollars per year (even in Canada), sequencing based tests like Genome Liberty's can save a lot of money for a health system or individuals, if they're paying for drugs privately.

The biggest potential customer for tests like this are still organized health systems or insurance companies.  Particularly insurance companies, who I think would pay for pharmacogenomic tests like this if it reduces the number of prescriptions given to people that simply can't metabolize the drugs too well, if at all.

The big obstacle facing the company, however, still seems to be coming from the FDA:
It is still not clear whether genetic tests sold directly to consumers will come under regulatory scrutiny. In 2010, the FDA warned 23andMe and other consumer genetics companies that their services amount to medical devices and thus need regulatory approval. But since then, the U.S. government has not come up with clear rules for these companies.
Deciding whether these tests are medical devices would calm concerns among people developing new technologies, particularly among funders and investors.  At this point, I think it's likely that genetic tests will eventually be considered 'medical devices', as both the US and Canada define procedures used to diagnose diseases or abnormal physical conditions as such.

On the other hand, in situation involving pharmacogenomics, like Genome Liberty is in, it could be argued that tests don't actually diagnose an 'abnormal physical condition', as rates of drug metabolism can cover a wide range even among normal individuals.  But that distinction is a fine one to make, one I think is better left for lawyers, attorneys, and others legally inclined to expand upon.

Like it or not, genetic tests like this are going to be as routine as ordering a blood test is today.  Jeffery Rosenfeld, a co-founder, closes with this advice:
Physicians don’t always trust the results of direct-to-consumer tests and may not have clear medical guidelines for how to use it. But the connections between the liver enzyme variants and drug response are well-supported, says Rosenfeld. If a doctor doesn’t want to accept these results, he says, then “find a different doctor.”