There have been a number of interesting review articles recently discussing the state of the art for personalized/precision medicine, and it’s clear that most commentators believe we are still very much in the early days.

Having just completed a quick review of the companion diagnostic tests that have been approved by FDA, I have to agree with this general assessment, but also see some very positive signs of progress.

Many tests, both FDA-approved and lab-developed, are used to identify patients who should and should not receive drugs, and many of these tests are often generically called “companion diagnostic” (or “CDx”) tests.

But there is a special subset of FDA-cleared and approved tests which are required to be used before prescribing certain drugs. By the strictest definition of the term, these are the true “companion diagnostic” tests according to FDA.

FDA maintains a list of these tests, and it includes 13 FDA-approved drugs which have a companion diagnostic test. Not surprisingly all but one of these drugs is a cancer therapy.

On the plus side there are now pesonalized therapeutics for seven different cancer types. The release last year of AstraZeneca’s olaparib for BRCA-positive ovarian cancer patients is certainly a positive development for sufferers of this under-served disease.

On the downside these targeted therapeutics rely on just a handful of biomarkers. Currently just seven biomarkers (ALK, BRCA1, BRCA2, BRAF, EGFR, Her2, and KRAS) are measured in companion diagnostic tests for cancer.

FDA and some drug makers are proud to mention that over half of all drugs under development have biomarkers associated with them. It will be interesting to see how many of those biomarkers end up in companion diagnostic tests, expanding the availability of truly personalized therapeutics.