Point-of-Care Diagnostics at the 22nd International Molecular Medicine Tri-Conference

Point-of-care diagnostics (POC) was an important track at the 22nd International Molecular Medicine Tri-Conference, held February 15–20, 2014, in San Francisco, Calif. According to Jeffrey DuBois, Ph.D., of Nova Biomedical (Waltham, Mass.), the POC market in 2014 was approximately $15.5 billion. The molecular diagnostics segment, which was the focal point of the symposium, was pegged at $5 billion, with a compound annual growth rate (CAGR) of more than 10%. The U.S. makes up about 47% of the global market.

For at least 50 years, the emphasis in clinical diagnostics development has been on larger, faster, lower-cost analyzers designed for core facilities. Both the drive to reduce costs and the Clinical Laboratory Improvement Amendments (CLIA) directives have forced consolidation in centralized laboratories. Samples are thus processed remotely, necessitating their transport from centralized laboratories to core laboratories via courier or express mail. This model is generally working, but niches are appearing, driven by the need for real-time, actionable results.

POC testing for time-sensitive diagnostics

Consolidated laboratories do not always serve the patient well. In the developed world, rural patients in particular often do not derive as much benefit as those who live in urban areas. In the underdeveloped world, patients may need to walk, sometimes for days, to find medical care. As witnessed during the recent Ebola outbreak, many infected individuals died while seeking medical attention, their remains posing a significant danger.

Hospital-acquired infections (HAIs) are another challenge. U.S. regulators and payers are pressuring hospitals to actively monitor and remediate HAIs, especially those caused by so-called superbugs such as Clostridium difficile.

POC testing at the clinic

The topic of pharmacies providing POC testing was introduced by Alex Adams of the National Association of Chain Drug Stores. The workflow starts with a patient assessment followed by POC testing. Physician assistants (PAs), aided by the patient’s electronic health records and medical history, provide a treatment plan that includes prescribing medication.

POC diagnostics in the home

Most health care is administered at home. In the developed world, thought leaders see the need for CLIA-waived diagnostics designed for the home. Automated blood pressure devices, tests to detect pregnancy and AIDS, and insulin treatment for diabetes are already available.

Home testing may be convenient, but to be most effective it should be coupled with telemedicine, that is, screening the data and dispensing the right therapeutic quickly. Home testing also raises logistical issues.

POC technology and products

A major component of the conference program was implementation. The POC system designs presented use disposable cassettes for the wet chemistry. Most utilize thermal cycling PCR. Amplification chambers are small, facilitating faster cycles and reducing power and cooling load. Two demonstrated chambers use isothermal amplification technology, where the signal builds exponentially with time. These appear to be faster and more portable.

The systems show thoughtful design from the patient to the therapy. For infectious disease cases, the fluidics cassettes are sealed after the assay. A 30-minute processing time seems to be the de facto design standard. As new biomarkers are identified and matched with therapeutics, the test panels will need to be updated.

Manufacturers want their products to qualify as “CLIA waived.” CLIA imposes requirements for safety and efficacy, depending on assay complexity and risk to the patient if the assay is not run as designed.

The POC products shown at the conference are reviewed in more detail below.

Atlas Genetics: Rapid diagnostics

Atlas Genetics (Trowbridge, U.K.) develops ~30-min diagnostics to test and treat infectious diseases using a POC model. The process starts with a fixed-volume pipet to inject the sample into the microfluidic cartridge. DNA is isolated from the sample matrix and amplified using PCR with thermal cycling. An electrochemical-labeled probe hybridizes to the target DNA. The electrochemical reporter group is released by an endonuclease for redox detection in a constant-voltage cell. A variety of ferrocene reporters are used, which enables multiplexing by programming the cell potential. The reagents are enclosed in a sealed cartridge that contains the amplification products; after the assay is complete, the identifying barcode is destroyed to prevent laboratory contamination or reuse. Atlas claims that electrochemical detection is more rugged and more quantitative than conventional fluorescence or absorbance.

Initial response to these products has been favorable. Patients appreciate quick treatment when the assay is definitive. One slide showed that, for HAI, definitive results facilitated a reduction in patient isolations and cost. Targeted therapy was initiated more rapidly and hospitalization duration was reduced. There are test panels for chlamydia, gonorrhea, methicillin-resistant Staphylococcus aureus (MRSA), C. difficile, human papilloma virus, norovirus and multiplexed sexually transmitted disease (STD). Comparison with a widely used assay for chlamydia gave 98% sensitivity and specificity.

Coyote: Quantitative PCR

According to Dr. Sabrina Li, founder and CEO of Coyote (Beijing, PRC), the U.S. has 35,000 physicians’ office laboratories (POLs) and 230,000 CLIA-waived laboratories. In the PRC, the Community Health Service has 400,000 locations, most of which can utilize POC systems from Coyote.

Dr. Li described two Coyote POC instruments, both of which use quantitative PCR (qPCR) to amplify and identify DNA. The key is to amplify DNA with no sample preparation. For Ebola, the blood is added to a reagent tube. A thermal cycler amplifies the DNA using a protocol optimized for the disease and a sample located in the Coyote Mini8, which provides a qPCR profile. Useful growth curves are obtained from the 10–500 copies generated. The control shows no signal, even after 55 cycles.

An impressive series of slides demonstrated field trials for Ebola monitoring in West Africa in the fall of 2014. The Coyote team analyzed 561 clinical samples showing 98.8% sensitivity. Typical run time is between one and two hours. The Mini8 is small enough to carry in one hand, operates on 12 volts and does not need to be calibrated.

Dr. Li previewed a new instrument called the InstantGene, which also uses rapid qPCR to provide completed assays from a drop of blood in 10–20 minutes. The estimated cost is $10/sample.

Fluoresentric, Inc: smartphone accessory

Fluoresentric, Inc. (Park City, Utah) showcased the XCR, a smartphone accessory that consists of a small amplification module that cradles the phone. The phone’s camera records the DNA amplification signals from isothermal DNA amplification. Results are delivered via a return phone call.

The design goal for the XCR is to provide pathogen detection, such as a flu strain. Features include: 1) 14 copies of DNA can be detected in 6 minutes—this is about a 30,000× increase in detection sensitivity over PCR, 2) it is 10 times faster than PCR and more resistant to PCR inhibitors than thermal cycling PCR, 3) there is only one moving part and 4) it costs under $200.

Lucigen: Zaire Ebola virus and C. difficile assays

Lucigen (Middleton, Wis.) featured the ClariLight product line, which includes instruments and application-specific reagents that assay for Zaire Ebola virus and C. difficile. ClariLight uses OmniAmp polymerases for loop-mediated amplification, with results available in 30 minutes.

The host instrument is about the size of a laptop. Since it is anticipated that the typical user will not have laboratory expertise, the workflow has been reduced to three simple steps that do not involve weighing, mixing or other intensive manipulations. The operator simply loads the sample; then the instrument performs the sample preparation, amplification and detection in a disposable cartridge. The manufacturer hopes the ClariLight is easy and robust enough to qualify for a CLIA waiver.

University of Otago: Thermal cycler-based instrument

A portable thermal cyling-based instrument for infectious diseases was also exhibited by researchers at the University of Otago in Dunedin, New Zealand. It is about the size of two 1-lb boxes of butter, with a similar weight. The small amplification chamber reduces power requirements.

Summary

The potential market for POC systems is sizable and includes both physicians’ office laboratories and the home market in the developed world. Instrument, reagent and information processing for CLIA waiver eligibility and FDA approval for home use will become a global de facto design goal. Changing the health-care paradigm to include POC diagnosis and treatment will certainly precipitate turf wars between current stakeholders. These will take time to resolve, but the real winner will be the patients and, hence, society, since outcomes will certainly improve.

Robert L. Stevenson, Ph.D., is Editor Emeritus, American Laboratory/Labcompare; e-mail: [email protected].