BBI Contributing Editor

SAN FRANCISCO, California – The 52nd annual meeting of the American Association for Clinical Chemistry (AACC; Washington), held here in late July, provided a venue for discussion of many of the current trends in clinical laboratory and non-laboratory in vitro diagnostic testing and also offered a glimpse of future trends in the industry. The clinical diagnostics market of today is mature, certainly from the perspective of overall revenue growth. Test volumes were dropping until recently and remain relatively stable in most segments. However, new developments in areas such as pharmacogenetics and targeted selection of diagnostic tests are beginning to transform in vitro diagnostics. In the future, as these new trends become more prevalent, the structure of testing, both in the laboratory as well as in alternate sites, will be altered significantly. Not only will new markers emerge for a number of important diseases, but molecular diagnostic testing will become an increasingly important discipline for the guidance of patient management.

Many new developments are occurring in immunodiagnostics. Key growth segments of the immunoassay products market, as shown in Table 1, include cardiac markers, tumor markers and prenatal testing. In the cardiac marker segment, troponin assays are becoming more important in patient triage, while high-sensitivity C-reactive protein is emerging as a key cardiac risk marker. Her-2-neu is an important example of a new cancer marker that is now used to select patients for a highly targeted form of therapy, namely treatment with the oncogene-specific drug Herceptin, manufactured by Genentech (South San Francisco, California). A new serum immunoassay for her-2-neu, under development by Bayer Diagnostics (Tarrytown, New York), promises to allow more effective guidance of treatment. New developments in diagnostic testing are also beginning to impact prenatal diagnosis, with the potential to provide major improvements in the detection of women at risk for premature delivery and to allow improved monitoring of low-birth-weight infants.

Demand grows for targeted diagnostics

Many factors are leading to an increased need for more efficacious diagnostic tools. Cost pressures are one important driver, having caused a major reduction in the number of analytes ordered in the routine chemistry section of the lab, where individual test requests are now the norm vs. panels of up to 19 analytes ordered in the past. Cost pressures also have forced a decline in selling prices in essentially all market segments.

Another factor that will become increasingly important is the prevention of medical errors, particularly errors in medication delivery, which may be responsible for more than 7,000 deaths annually in the U.S., according to estimates offered by Dr. James Nichols of Johns Hopkins University Medical Center (Baltimore, Maryland) at AACC. Other factors leading to an increased demand for targeted tests include the development of new drugs that attack specific molecular targets, leading to a need for tests to verify the presence of such targets, and increased efforts to tailor therapy for individual patients.

Prevention of medical errors is expected to take on increased importance in the diagnostics market of the future. While there are many potential sources of such errors, most – such as delivery of a medication causing an adverse reaction – result from a lack of information. This fact underlies growing emphasis on evidence-based medicine. Peter Wedlund, PhD, of the University of Kentucky (Lexington, Kentucky), said some 2 million adverse drug reactions occur each year as a result of prescription drugs being taken improperly, and there may be as many as 106,000 deaths per year that are due at least in part to such errors. The cost to the U.S. health care system for the treatment of those errors is about $4.3 billion. And there is a 2.5-fold increase in adverse effects for patients who take medications that require a specific enzyme for drug metabolism who are genetically deficient for that enzyme. Another example is cancer patients who express certain oncogenes, such as p53, and who consequently have a very different response to standard chemotherapy as compared to other patients. In such situations, the use of tests for specific response markers to identify patients at risk for an adverse reaction or poor response to treatment can result in a major improvement in outcome.

The cost of performing genetic tests for predisposition to an adverse reaction is relatively high, between $100 and $500 per sample, since test volumes are typically small and the cost to implement testing is high ($40,000 to $300,000 for equipment and costs related to personnel, training and accreditation). As the number of genetic characteristics of interest expands due to information emerging from the Human Genome Project and related efforts, test volumes are likely to increase. At high volume, according to Wedlund, per-test cost can drop to as low as $8 to $10. As cost barriers decline, the adoption of genetic testing to help guide drug therapy will expand not only in labs that are currently performing such testing, but also in many other labs that have not yet begun to use such technologies.

Even with the existing relatively high cost of genetic testing, some applications can prove cost-effective if testing is performed selectively on at-risk populations, particularly if the total cost of disease management is considered. If genetic testing is used to determine if a pregnancy should proceed in families that have already produced one child with a genetic disorder such as cystic fibrosis, the savings per family can be many thousands of dollars (see Table 2).

In another example of potential cost savings that can be realized with genetic testing, a study of the impact of testing for multi-drug resistant tuberculosis found that use of a nucleic acid test for drug-resistant TB strains costing $360 per patient resulted in a total cost savings of between $62,566 and $238,104 depending on disease severity. Savings resulted mainly from reduced hospital stay, which was lower if the patient were treated with the most effective drug from the outset of therapy. This example demonstrates that diseases such as serious infections, cancer and perhaps some forms of cardiovascular disease that are costly to treat if errors in therapy occur are good targets for the use of selective testing to help determine the correct therapy to be used.

Other examples of attractive applications for genetic testing include guidance of treatment for mental illness, oncogene analysis (e.g., for her-2-neu amplification) and tests for genetic variation in pathogens such as HIV leading to drug resistance. Genetic tests may also find important applications in improving the predictive value of other tests, by providing supplementary information that helps to confirm that a course of therapy chosen based on the results of conventional tests is in fact correct.

Bioinformatics also will be important in allowing new discoveries in genomics to be implemented in clinical practice. Bioinformatics will be particularly crucial in allowing effective use of the results of tests performed using microarrays capable of assessing a large number of genetic determinants. Companies including Affymetrix (Santa Clara, California), Nanogen (San Diego, California), Aclara Biosciences (Mountain View, California), InCyte Genomics (Palo Alto, California) and Research Genetics (Huntsville, Alabama), while focusing now on gene discovery, are expected to develop clinical applications of genetic arrays in the future. Many firms are likely to partner with established suppliers of in vitro diagnostic products, such as Becton Dickinson (Franklin Lakes, New Jersey), Beckman Coulter (Brea, California), and Roche Diagnostics (Indianapolis, Indiana) to commercialize their technologies for clinical applications.

Cancer testing enters new era

One of the most important applications of emerging targeted test methods is cancer diagnosis, and monitoring of cancer therapy. Testing for her-2-neu over-expression in breast cancer is a key application at present, using immunohistochemistry technology to detect the oncogene product, or in situ hybridization to detect the oncogene directly, in tissue biopsy specimens. Bayer Diagnostics is seeking FDA approval for a serum assay for her-2-neu that could have important applications in monitoring of therapy, and perhaps in initial diagnosis. The serum test is expected to be an excellent tool for monitoring patient response to therapy using Genentech's Herceptin drug. Walter Carney, PhD, of Oncogene Sciences (Cambridge, Massachusetts), now part of Bayer Diagnostics, said the new her-2-neu serum test detects a soluble form of the her-2-neu receptor that is amplified in breast cancer. Measurement of her-2-neu also may be important in other cancers, since the soluble form of her-2-neu is also found in lung, prostate, pancreatic, ovarian, gastric, colon and bladder cancer, in addition to breast cancer.

The test may also prove important in selecting patients for therapy, an application that was initially not believed to be viable. At present, a positive tissue biopsy test is considered the definitive determinant of patient eligibility for Herceptin therapy, but recent studies with the Bayer serum test have shown that some patients may show a positive serum level as their disease progresses even though the initial tissue biopsy was negative. It is possible that some patients who could benefit from Herceptin therapy are being missed by existing test methods, and that the use of serum testing could help to identify additional patients who may benefit from Herceptin treatment. However, more studies are needed before such use.

A number of questions remain to be answered regarding the widespread adoption of new targeted tests for markers such as her-2-neu. First, the most appropriate type of test to be used must be determined for each new marker. For example, her-2-neu amplification can be analyzed by assessing gene copy number by in situ hybridization using nucleic acid probes – an FDA-approved test is available from Vysis (Downers Grove, Illinois) – or by the use of an immunohistochemistry test or a serum assay for over-expression of the her-2-neu protein. Since the her-2-neu protein is the entity targeted by Herceptin, some pathologists argue that an immunochemical technique is most appropriate. However, most recent studies indicate that protein over-expression is closely linked to gene amplification, and in situ hybridization techniques have appeared to be the more reliable methodology when issues such as epitope loss during specimen processing are considered.

Another issue is biochemical variation of the target analyte. In testing for infectious agents such as HIV, for example, or for diseases such as cystic fibrosis that are caused by multiple genetic defects, tests for specific targets can miss important disease-related variants. Development of tests that can detect all clinically relevant targets is challenging at best. Many new drugs are under development that will have specific mechanisms of action, similar to Herceptin, but tests for their biochemical targets have yet to be developed. Sequencing of nucleic acids could provide one answer, but so far no low-cost, automated, widely available technology has been developed for general purpose diagnostic sequencing. The alternative is techniques such as nucleic acid arrays that can detect multiple targets simultaneously in a single assay. Such techniques still require that specific target sequences be known beforehand, but at least provide a viable approach for identifying patients who are candidates for treatment. In the future, targeted testing technologies will be widely used to guide treatment, but adoption will continue to be limited by the rate at which new tests can be developed to identify and quantitate therapeutic targets.

Screening tests employing specific markers are continuing to increase in importance, particularly for tests addressing major public health problems. Testing for prostate and cervical cancer is an important example of trends in this area. The detection of cervical cancer, historically performed using PAP smear screening, has now been revolutionized by the introduction of testing for human papilloma virus using nucleic acid probe tests from Digene (Gaithersburg, Maryland) and marketed by Abbott Diagnostics (Abbott Park, Illinois). Such tests are replacing assays to detect protein epitopes with immunochemical methods and are enabling a major improvement in the ability to detect cancer development at an early stage, and to assess its aggressiveness. Another example is screening for chlamydia infection, where new amplified nucleic acid tests allow detection of infection using urine specimens, whereas in the past a swab specimen, which is much more difficult to collect than urine, was required. Such advances make testing applicable to a wider range of patients and should help to further reduce morbidity due to infectious diseases.

The market opportunity for new cancer tests is substantial as a result of the large number of new cases (about 1.22 million in the U.S. in 2000, according to the American Cancer Society). As shown in Table 3, U.S. sales of tumor marker tests totaled an estimated $118 million in 1999 and are forecast to reach $211 million by 2005, representing a compound annual growth rate of 10.2%. Use of established markers such as CEA for colorectal cancer, PSA for prostate cancer, CA15-3 for breast cancer, CA-125 for ovarian cancer, and CA27-29 for breast cancer are continuing to expand, along with the number of new patients. Continued growth in the number of existing patients as improved therapies have led to increased survival rates also has contributed to an increase in the demand for tumor marker testing. At Memorial Sloan-Kettering Cancer Center (New York), for example, as described by Morton Schwarz, PhD, at an AACC press conference, combined annual test volume for CEA, PSA and CA15-3 increased 14.9% per year between 1987 and 1999, with PSA showing the largest growth (36.6%) and CEA the smallest (6.1%). Increased used of new markers such as NMP22, a bladder cancer assay marketed by Matritech (Newton, Massachusetts), and the new free PSA test from Beckman Coulter are driving market expansion. Future adoption of additional immunochemical tests, such as the Bayer her-2-neu serum assay, and NMP66, a new, development-stage marker for breast cancer from Matritech, is expected to lead to continued growth. In addition, a new market segment already is emerging for nucleic acid tests for cancer, including HPV gene probe assays from Digene and in situ hybridization tests for her-2-neu from Vysis. The nucleic acid diagnostics segment of the cancer testing market is likely to exhibit even stronger growth than the immunoassay market, particularly as additional new markers are discovered as a result of the Human Genome Project, and as automated testing systems now under development by a number of suppliers enter the market.

Cardiac marker testing still expanding

Another growing segment of the market that is increasingly relying on the use of more targeted, specific markers is tests for diagnosis, risk stratification and therapeutic monitoring of cardiovascular disease. The most rapidly growing product segment is point-of-care cardiac marker testing systems. Table 4 on page 201 lists systems on the market and under development.

The segment is becoming crowded, with four products on the market in the U.S. and another four in various stages of development. The most recently introduced system, the BioSite Cardiac Triage, has captured a significant share of the market in the short period following its launch in early 1999. The Cardiac Triage is the first truly portable cardiac marker system launched in the U.S. that is capable of providing quantitative results at the bedside and offers the fastest turnaround time available at present. Systems that will probably be launched within the next year for cardiac marker testing include the ImmuGold from Diagnostic Products and the First Medical system. ImmuGold will offer rapid turnaround time of five minutes, while the First Medical system provides considerable flexibility in choice of analyte panels.

POC cardiac marker systems are being used in a variety of testing sites. Some, such as the Stratus CS, are primarily used in a lab setting: 85% of Dade Behring's placements of Stratus CS are in a lab settling or at the point of specimen acquisition (i.e., at specimen log-in). This situation holds even though the system is primarily purchased because emergency department physicians want faster turnaround time. Other new systems under development will offer a higher degree of portability and menu flexibility (e.g., the i-STAT and ThauMDx systems), indicating future trends for products in this segment.

Prenatal diagnosis represents opportunity

Another area of opportunity in clinical diagnostics is prenatal diagnostics. Because of advances in clinical management of premature birth, resulting in an increase in survival rates from 10% in 1960 to over 50% now for premature infants of all birthweights, the demand for prenatal testing and for testing of premature infants following birth is continuing to grow. Clinical syndromes that must be managed in the premature infant include respiratory distress syndrome, extreme prematurity, pulmonary hypertension, meconium aspiration, congenital heart disease, enterocolitis, hyper-bilirubinemia, gastrointestinal reflux and sepsis. Important needs in testing of premature infants include microsampling (total blood volume can be as small as 40 milliliters), rapid turnaround time, high accuracy, specific tests such as caffeine and nutritional panels, and availability of consultation for test results.

Point-of-care testing also is an important part of prenatal patient management, and continuous in-line monitoring is being implemented for care of premature infants to provide more detailed data on trends in patient condition because of demands for immediate availability of results in the intensive care setting. Adeza Biomedical (Sunnyvale, California) is one company that is addressing the opportunity for POC testing in prenatal care, having developed a test for fetal fibronectin that is a good predictor of premature delivery. The test is now available in a POC immunoassay format. Other important tests, both requiring high sensitivity and, optimally, rapid turnaround time for prenatal applications, include hCG and PAPP-A. When used in conjunction with an ultrasound technique (nucular translucency), those tests have been shown to allow early (first trimester) detection of Down syndrome in 90% of cases. Existing techniques only allow detection in the second trimester and have a sensitivity of 70%. While such testing is relatively expensive at $119 per patient, the cost savings are $1,200 per patient tested. Prevention of premature birth is an even more important goal, since it may cost up to $1 million for management of a premature infant.

Rapid immunoassay development

As an increasing number of specific markers are discovered to help diagnose certain types of disease, and to detect specific therapeutic targets, demand will grow for technologies that allow rapid development of immunoassays. In many cases, the total number of patients who are candidates for testing may be quite small. A number of companies are offering turnkey systems for development and small- to medium-scale manufacturing of qualitative immunoassays. One of the leaders in this area is BBInternational (British Biocell; Cardiff, United Kingdom), and its partners, Kinematic Automation (Twain Harte, California) and Millipore (Bedford, Massachusetts). BBInternational has developed a semi-automated system using test substrates from Millipore, equipment from Kinetic and reagents from BBInternational. The user need only supply the antibodies to be used in the assay and combine them with the components supplied by the companies. BBInternational also can supply gold-conjugated antibodies for certain assays that can be used as the labeled, signal-generating element of an assay. Using those antibodies, BBInternational can provide a complete Lab-in-a-Box system that can be used to rapidly develop a new qualitative immunoassay in card or test strip format, which can then be quickly converted to a manufactured product. The Lab-in-a-Box system is aimed at smaller companies producing up to 15 million tests per year. If volume expands beyond that level, the user can switch to larger-scale automated equipment provided by Kinematic Automation to scale up. To date, BBInternational has installed three systems in South Africa, Saudi Arabia and Bulgaria, and plans to place about 12 systems per year worldwide. Asia, and in particular Korea, is one region where the companies involved in the Lab-in-a-Box program believe significant opportunity exists.

Another unique platform for low-cost, POC immunodiagnostic assays has been developed by Biognosis GmbH (Julich, Germany). The ABICAP LABSTIC technology is targeted at uses in point-of-care testing in small and medium-sized institutions and offers quantitative results, typically in about 10 minutes. The LABSTIC system includes a fingerstick sampling device that is inserted into a cylindrical cartridge containing the test matrix and reagents. The assembly is inserted into a hand-held reader, which actuates mixing, incubation and reading. Readout is performed using light-diffusion analysis, providing a sensitivity of 100 femtomoles. The prototype reader costs about DM 800 (about $400) and each cartridge costs approximately DM 3.50 ($1.75). The company is seeking collaborators who are interested in developing and marketing quantitative POC assays based on the LABSTIC technology.