Trends in Personalized Cancer Diagnostics with Highly Sensitive Digital PCR Our expertise

Programs designed to promote the early screening of cancer demonstrably improve healthcare outcomes. Early cancer detection is especially important due to the nature of oncological diseases.

For example, one of the most common but aggressive forms of lung cancer, NSCLC, has a 63 percent chance of survival after five years if discovered while it is still localized, but this number drops to less than seven percent after five years if it had already spread into the brain or bones. It is an example where early detection is the only existing viable way to prevent deaths.

Digital PCR, with its high sensitivity, allows for the detection of cancerous cells or tumor DNA even in trace quantities contained in human blood samples. This technique is called liquid biopsy. By enabling cancer screening with a simple blood draw, more patients can opt for cancer screening during routine health checkups. It also removes the need for frequent physical biopsies, which can lead to stress for both doctors and patients, especially seniors that have difficulties with the recovery process.

Digital PCR, along with quantitative PCR and next-generation sequencing, are some of the promising technologies that are under development for enabling widespread liquid biopsy. An example is the Stilla Technologies multiplexed EGFR 6-color kit, which can look at up to 32 different mutations of the EGFR gene from a blood sample.

Modern precision therapeutics such as immunotherapies and molecular-targeted therapies, often target specific genetic mutations. They work by changing or preventing the pathways these mutations take to create tumors.

As such, these drugs will only work for patients with a subset of mutations, such as deletions or insertions of genetic material. The FDA approves companion diagnostics, which are tests that must be taken and confirmed for these therapeutics to be offered as treatment.

The ability to multiplex and give accurate diagnostics makes Digital PCR a great potential solution for drug manufacturers looking for companion diagnostics tests for their drugs. Currently, liquid biopsy companion diagnostics is in its early stages. The first approval was Roche’s “cobas” quantitative PCR test, which was approved in 2016. Since then, several high-profile NGS laboratory tests from Foundation One and Guardant have been approved.

No digital PCR-based companion diagnostics has been approved yet. A list of ongoing clinical trials using digital PCR as a diagnostic or as confirmation technique is presently underway.

Tests can be done to determine whether a person has become resistant to a specific drug and needs to change course in a treatment regimen. Particularly in personalized medicine, it is often necessary to monitor the same genetic markers as the therapeutic is treating. This is often also called dynamic monitoring as the major benefit is the ability to make dynamic changes based on tumor burden.

With the ability to quantify small sample volumes to absolute values, digital PCR is a good strategy for monitoring therapeutics. An example is using digital PCR for Minimal Residual Disease monitoring in leukemia.

Another example is with EGFR tyrosine kinase inhibitor (TKI) therapeutics, in which even in highly effective cases, most resistances are acquired within six to 12 months. A first, second, and third line of therapeutics are available once resistance is acquired, and the drug used should be switched to match the acquired resistance.

These three trends in personalized cancer diagnostics create an ecosystem of tests that help grow precision medicine into acceptance and widespread usage. The role of digital PCR in this ecosystem should be seen as a strong contending technology for performing diagnostics, and a great confirmatory test to quantitative PCR and next generation sequencing tests.