The genetic revolution created an exciting field of laboratory medicine based on analyzing human genes to better understand diseases, how they develop, and the most effective ways to treat them. Today molecular diagnostics is a game changer for clinical laboratories of all sizes, offering more powerful tools for earlier and more accurate detection of disease and giving laboratories a key role in the emerging field of personalized medicine.
In recent years, molecular testing has become more routine, thanks mostly to the development of automated instrument systems that provide accurate results utilizing polymerase chain reaction (PCR) and other molecular detection technologies for identification and DNA/RNA measurement of infectious pathogens, tumors, and human genes. Even smaller labs are becoming more interested in acquiring molecular capabilities because they can benefit from simpler, easier to use, labor-saving systems. Further simplification of molecular assays and instruments will foster wider implementation by community hospital laboratories. With these new, more efficient systems, hospital laboratories are also seeing increased revenue opportunities.
Most important, by adopting molecular diagnostics, laboratories are having a greater impact on the treatment and care of patients. These advanced systems are helping physicians treat infectious diseases sooner and with more precision. The virology lab, for example, is already realizing the benefits of molecular technology. For diagnosing viral diseases, molecular methods are supplanting culture-based testing, which once was the gold standard for viral diagnosis. Waiting two days or longer for test results, which can delay important treatment for patients, is no longer necessary.
PCR assays, for example, are used routinely instead of cultures to diagnose respiratory infections. Molecular tests for pathogens, such as RSV, rhinoviruses and influenza A and B, help physicians to identify the infections at early stages, select treatments, prevent further transmission, and reduce inappropriate antibiotic prescribing.
Laboratories with molecular testing capabilities also are a key participant in hepatitis C therapies. With two new drugs approved by the FDA this year, physicians can treat this disease more effectively with help from viral-load measurements. Physicians now order molecular assays for HCV following initial diagnosis with serological tests. Viral-load results help determine whether to begin antiviral therapy, influence decisions on dosing and therapy duration, and can help identify drug-resistant strains. Testing can be continued at regular intervals to monitor therapy. The goal is to ensure that the virus is under control or eradicated, as shown when viral loads are below detectable levels.
Anti-viral medications for treating HIV patients also require ongoing monitoring with molecular diagnostic tests. The success of anti-viral drug therapies for HIV patients is determined by HIV viral-load reduction. Highly sensitive molecular assays can identify minute levels of viral DNA and allow physicians to determine if the patient is responding to treatment.
Molecular technology has also brought the clinical lab into the exciting, rapidly emerging field of personalized medicine. So far, oncology patients have been the primary beneficiaries of this movement, as molecular diagnostic tests can identify patients more likely to benefit from new cancer therapies. They tell physicians if a tumor is genetically vulnerable to treatment with targeted, gene-based drugs.
For breast cancer patients, studies have shown that detecting the HER-2 gene using fluorescence in situ hybridization (FISH) technology identifies patients who will benefit from treatment with Herceptin, which targets HER-2 and has saved thousands of lives since coming on the market in 1998. One in four women with breast cancer has the gene. The laboratory plays a major role in guiding treatment decisions by advising oncologists if genetic test results indicate the patient is a good candidate for Herceptin treatment.
On August 26, there was another major step forward in personalized medicine with the simultaneous FDA approval of crizotinib, a new treatment for non-small cell lung cancer (NSCLC), and the companion diagnostic, a FISH test for detection of ALK gene rearrangements on the 2P23 chromosome. Crizotinib is an ALK inhibitor which blocks an aberrant protein that can spur tumor growth. Laboratories now can use the ALK FISH probe kit to identify ALK-positive patients whose lung cancer should respond to crizotinib therapy. Some 5% of NSCLC patients have the ALK gene abnormality. This relatively new phenomenon is based on the realization that physicians can no longer pursue one-size-fits-all treatment programs, especially for the sickest of patients.
In the next decade, clinical laboratories will assume a more prominent role in oncology by assisting physicians with the interpretation of complex genetic test data, such as explaining the clinical significance of various tumor and pathogen genotypes, and identifying patients for treatment with the expected steady stream of new gene-based therapies for cancer.
Today, many hospital executives are deciding whether starting a molecular diagnostics laboratory is right for their institutions and are evaluating financial scenarios to support molecular diagnostic testing. Important considerations include potential revenue generation and cost avoidance. Molecular test reimbursements are more attractive, and net revenues for molecular assays far exceed those for clinical chemistry panels, immunoassays, and culture tests. Also, acquiring a molecular testing system can eliminate a significant volume of costly send-out tests.
Looking at cost-avoidance benefits, let’s consider MRSA, one of the most common and expensive-to-treat infections in hospitalized patients. According to a study published in 2006 in the International Journal of Antimicrobial Agents, one MRSA infection costs a hospital $14,000. So implementing a molecular-based MRSA screening program could save $7 million in one year by identifying 500 MRSA-infected patients before they are admitted.
For most hospitals, start-up costs should not be prohibitive considering the significant clinical and financial benefits of molecular diagnostics. Simplification of molecular assays and instruments will be critical to foster significant movement into laboratories with medium and small testing volumes. It’s a game changer for clinical laboratories, no doubt, and for labs that haven’t adopted molecular testing yet, it may well be time to move off the sidelines.
Patrick Groody, PhD, is Divisional Vice President, Research and Development, at Abbott Molecular.
