A Diagnostic Smorgasbord

IN THIS ISSUE
To know if the pancreatic cancer is truly gone, use ddPCR
Thirteen seconds to know whether a TBI patient will wake up
You already own a device that can dx mild cognitive decline
Diagnosing CSF infection in real time
Continuous ultrasound for high-risk pregnancies
Does this pup have what it takes?

For many serious conditions, early diagnosis is the key to successful treatment. This week we highlight a group of tests that improve the odds of getting that critical answer more quickly.

As we’ve often said in this newsletter, pancreatic cancer remains difficult to successfully diagnose and, therefore, treat. Part of the problem - and one we haven’t touched on much - is how often it recurs after treatment. The most common type of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC), and after it’s removed it comes back about 57% of the time. Just as with initial diagnosis, early diagnosis of recurrence is key - for prognosis as well as treatment.

A recent study evaluated two blood tests that monitor for pancreatic-cancer recurrence. Both look for circulating tumor DNA (ctDNA) that includes the KRAS mutation, which is found in about 90% of these cancers. (KRAS is the mutation that’s targeted by the new pancreatic-cancer drug that everyone’s rightly excited about.) One relies on next-generation sequencing (NGS), which is the type of test most commonly used in this situation. The other uses digital droplet PCR (ddPCR), a technique in which the sample is divided into thousands of tiny droplets before analysis.

The ddPCR technique is known as a more sensitive test than NGS, and this small study (106 patients) bore that out. After surgery, ddPCR detected tumor KRAS DNA in 56% of patients, compared with 9% for NGS. After chemo, the results were similar: ddPCR was positive in 60% of patients, versus 5% of those tested with NGS.

After a severe brain injury, one dire question must be answered as quickly as possible: Will this person ever wake up? According to a recent study, clinicians may be able to get the answer in 13 seconds flat, using a low-tech eye test.

The test, known as the late light-off response, turns a well-known eye test upside down. Instead of evaluating how a person’s pupils respond to a sudden, bright light (that’s the pupillary light reflex, or PLR), it measures how long it takes for the pupils to respond to sudden lack of light.

Brain-injury patients whose pupils took more than three seconds to respond appropriately to sudden darkness were significantly less likely to wake up over the next seven days, even if their other levels of responsiveness were normal. The test takes about 13 seconds to administer, using the same standard tools used for PLR.

It’s your cell phone. Okay, technically it’s an app, but it’s one that’s designed for use at home, on mobile devices.

The app itself has already been shown to be capable of diagnosing mild cognitive decline. What’s new is a paper demonstrating that the app can make that diagnosis in a shorter period of time (30 weeks) than standard, in-person cognitive tests. That’s because people can test themselves frequently at home, while the standard tests are only administered once or twice a year, at office visits. In addition — and for the same reasons — the app can also track subtle cognitive changes over time.

Too much fluid in or around the brain is a dangerous thing. Many brain injuries and diseases require clinicians to place drains that continuously remove excess cerebrospinal fluid (CSF), but those drains can also be a pathway for infection. ICU nurses send fluid samples for testing as often as is reasonable, but that ends up being only once a day or two - those nurses have a lot to do, and getting the samples is time-consuming.

A paper in Science Translational Medicine provides proof of concept for a device that can test CSF continuously. The tool is about the size of a smartphone and attaches directly to the tubes that drain fluid from the patient. Its sensors measure the fluid flow rate, as well as three biomarkers of infection: glucose, lactate, and pH. Since the device’s measurements correlated well with laboratory results, it could one day be used in ICUs to give clinicians a heads-up about impending infection in real time.

Ultrasound is the cornerstone of fetal monitoring, but it only gives clinicians a snapshot of how the fetus is doing at the moment the exam is performed. For high-risk pregnancies, it would be very useful to have more consistent monitoring, to catch abnormal changes before they have a chance to impact fetal development.

A paper in Nature Biotechnology describes a tool that can solve this problem. It’s a flexible, adhesive patch about the size of your palm that uses ultrasound to continuously monitor blood flow in both the umbilical cord and one of the fetus’s major arteries. It can also provide measurements that allow clinicians to track fetal growth. The device works even when the mother and / or fetus are moving — a critical feature, given how active some of those little ones can be.

For now, the authors envision the device being used in hospitalized patients. They are working on a wireless device, which could one day be used in patients at home.

Training a guide dog is wicked expensive. Depending on the type of training they need, it can cost up to $50,000 — and 60% of dogs that start guide training wash out. That translates to a loss of more than $12,000 per dog. So it would be awfully nice to know if a particular pup has the Right Stuff before training even starts.

Genomic testing might be able to make that call. One team of researchers looked at genomic sequences for 1,100 Labrador retrievers that were part of the International Working Dog Registry (IWDR). The researchers correlated the genetic information with the dogs’ scores for 17 traits on the IWDR Behavior Checklist - the ones that are likely to cause a puppy to fail its guide-dog training.

They found that genomic data was a better predictor of a dog’s success for at least 11 of the 17 traits. Not only could that be helpful to decide whether to start a pup in training, it can also be used to determine which dogs should be bred. Over time, that could improve the percentage of puppies that complete the training.

🎙️ New Episode Alert:

Madhuri Hegde, SVP and CSO of Revvity, discusses how her company leverages partnerships and broad expertise in both life sciences and diagnostics to solve patient problems.

Listen in: ontargetpodcast.com

Join the conversation: If you’re leading innovation in this space and want to share your perspective, we want to hear from you. info@ontargetpodcast.com