Technical Feasibility Established for MosaiQ Hepatitis B Surface Antigen Assay

Edinburgh, UK based commercial-stage diagnostics company Quotient Limited has announced that results generated using the company’s MosaiQ transfusion diagnostics methodology indicate a high degree of sensitivity and specificity for this Hepatitis B Surface Antigen (HBsAg) assay.

The feasibility study was conducted in collaboration with Intuitive Biosciences, Inc. a Madison, Wisconsin based firm that provides high-throughput protein analysis tools for the life science industry, bringing together multiplex protein detection technology with serological assays of products and services. The Company’s Arrayed Immuno-Multiplexing platform delivers a continually expanding portfolio of protein analysis tools and related research services. Intuitive Biosciences examined a total of 96 positive and negative samples.

Quotient’e MosaiQ is described as a next generation automation platform designed to transform the $2.8 billion transfusion diagnostics market. Quotient notes that delivery of safe and compatible blood products to patients is critical, and that the MosaiQ platform will allow for full characterization (using existing serological approaches) of patient and donor red blood cells and plasma utilizing a single consumable. Also being developed to serologically undertake full, mandatory virology screening for donor blood, Quotient says MosaiQ will offer potential for improved clinical decision-making and enhance efficiency through providing a more complete automation solution.

MosaiQ is currently under development and not available for sale in the United States, but Quotient plans to begin field trials for its full donor disease screening consumable (comprising CMV, Syphilis, HBV, HCV, HIV, HTLV and T. cruzi) in 2016. The disease screening consumable for donor testing is being developed for screening both red cell and plasma donations.

The purpose of transfusion diagnostics is to ensure safety of the blood supply. There are two components: screening blood donations and patient samples to ensure compatibility of blood group before transfusion, and screening blood donations for known pathogens to prevent transmission of infectious agents. The global transfusion diagnostics market is large and established, with total annual product sales amounting to $2.8 billion in 2011, $1.3 billion of which were within the U.S. Quotient estimates that nearly two-thirds of testing is done in the highly concentrated donor testing market, while the remaining third is in the much more fragmented hospital setting.

Hepatitis B, a viral infection primarily affecting the liver and the cause of both acute and chronic disease, is transmitted through contact with the blood or other bodily fluids of an infected person. Acute symptoms associated with initial hepatitis B virus (HBV) infection include vomiting, yellow skin, abdominal pain and fatigue. While the majority of infections do not lead to chronic infection, most people infected around the time of birth develop chronic hepatitis B. Chronic infection can potentially lead to development of cirrhosis of the liver and liver cancer, both frequently resulting in death. According to the World Health organization, an estimated 240 million people are chronically infected with HBV (defined as HBsAg positive for at least 6 months), resulting in approximately 650,000 deaths each year. Consequently is critical that all donated blood for transfusion purposes is effectively screened for HBV.

Leveraging the company’s 30 years of transfusion diagnostics expertise, with MosaiQ, Quotient has combined novel manufacturing techniques with well-characterized blood grouping and disease screening tests to create a multiplex testing consumable for use on a high-throughput instrument. Through miniaturization, they have been able to combine a full portfolio of existing serological tests on two distinct consumables for use on MosaiQ: one for blood grouping and one for serological disease screening. Both consumables have been designed to run in parallel, utilizing the same donor sample and the same MosaiQ instrument and to address worldwide requirements for blood grouping or serological disease screening.

MosaiQ has been enveloped to simultaneously determine the full antigen profile of patient and donor red blood cells, and to identify all clinically significant antibodies in patient and donor plasma (Blood Grouping), and additionally to serologically screen donor blood for specific viruses (Disease Screening). Quotient are including tests to screen serologically for Syphilis, Hepatitis B Surface Antigen, Hepatitis B Core Antibody, Hepatitis C Antibody, HIV Type 1 and Type 2 and Human T-Lymphotropic Antibodies Type I/II, along with a test for CMV. The MosaiQ disease screening consumable has been specifically designed with the capacity to include additional disease screening tests as may be mandated by regulatory requirements.

Quotient have conducted extensive feasibility work internally to demonstrate the MosaiQ methodology’s performance compared with predicate technologies for specific antigen typing and antibody identification tests to be included on the MosaiQ blood-grouping consumable. This work has been focused on demonstrating specificity of antigen typing tests for key blood group systems (ABO, Rh and Kell) and specificity and sensitivity of the antibody identification assay. They have designed these studies to evaluate the MosaiQ methodology with a large data set and direct future development efforts.

The HBsAg assay exceeded Quotient’s target of sensitivity and specificity for this phase of development, demonstrating that the MosaiQ methodology can be applied to HBsAg detection. Findings from the study demonstrated sensitivity of 98.6% (23 detected versus 24 positive samples) and 100% specificity (72 negative samples reported as negative). In addition, the MosaiQ methodology detected the HBsAg standard of 0.2 International Units Per Milliliter. As a result of these positive study results, Quotient says it now plans to complete development and validation of the HBsAg assay, including improvement of the analytical sensitivity for inclusion on the MosaiQ disease screening consumable for donor testing.

“These positive initial results for our HBsAg assay further support the expanding utility of MosaiQ as an innovative and disruptive diagnostics platform with broad commercial application within the donor testing market of transfusion diagnostics,” says Paul Cowan, Quotient’s Chairman and CEO. “We have now established technical feasibility for HBsAg, Cytomegalovirus (CMV) and Syphilis assays and look forward to the development of additional assays for the detection of Hepatitis C virus (HCV), Human Immunodeficiency virus (HIV), Human T-Lymphotropic virus (HTLV) and Chagas disease (T. cruzi). This combination of assays will allow Quotient to offer a full suite of currently mandatory disease screening tests on a single consumable using MosaiQ.”

Blood Grouping

Prior to a blood transfusion, or when there’s likelihood that a blood transfusion might be required, extensive blood grouping procedures are undertaken on patient and donor blood using in vitro diagnostic products. These procedures ascertain the blood group of the patient and ensure compatibility of the donor blood. The testing regime is designed to prevent transfusion reactions, which can range from mild to fatal.

Quotient notes that red blood cells (the cellular portion) and plasma (the fluid portion) are blood’s principal components. On the surface of red blood cells are antigens that determine an individual’s blood group (A, B, AB, O), or ABO group, and type (RhD positive or RhD negative), or Rh type. Additionally, there are at least another 32 clinically significant blood-group antigens that may be present on patient and donor red blood cells. Plasma contains many different kinds of proteins, including: (i) naturally occurring blood-group antibodies; (ii) blood-group antibodies developed by the body in response to foreign red blood cell antigens introduced during transfusion (allo-antibodies); or (iii) blood-group antibodies developed following pregnancy. Blood-group antibodies mirror the antigen families that are present on red blood cells. In its normal state, blood does not contain antibodies that will react with its own red blood cell antigens (auto-antibodies).

Consequently due to potential for reactions of blood-group antigens and antibodies, correct identification of blood-group antigens or antibodies present in donor and patient blood before transfusion is crucial. If a donor’s red blood cells contain antigens that are recognized by and react with existing blood-group antibodies in the patient’s plasma, transfused red blood cells could be destroyed in a potentially life-threatening reaction. Identification of blood-group antigens on donor and patient red blood cells is typically referred to as blood typing or ‘basic antigen typing,’ and more comprehensive characterization referred to as ‘extended antigen typing’. Identification of blood group antibodies in plasma is typically referred to as ‘antibody identification.’

Patients potentially requiring a blood transfusion will generally be blood grouped, including pregnant women, cancer patients undergoing chemotherapy, patients undergoing surgery or patients suffering from chronic diseases that require regular blood transfusions, such as thalassemia or sickle cell disease.

Quotient points out that Blood Grouping techniques have remained relatively unchanged for many years, and while instrument platforms allowing limited automation have been introduced, they still require significant manual intervention in approximately 5-10 percent of cases in order to perform extended Blood Typing (or phenotyping) or a full Antibody-ID. Therefore, a significant proportion of Blood Grouping cost incurred due to the ongoing requirement for manual testing.

The importance of Blood Grouping and the limitations of existing instrument platforms require highly skilled and educated blood banking technologists to support blood testing needs of hospitals, donor centers and reference laboratories. Moreover, with over 50 clinically significant antigens and antibodies to characterize, liquid reagent requirements for blood grouping (whether performed on instruments or manually) are both complex and extensive. Conventional reagents also have limited shelf lives (as low as 28 days in the case of red cell products) and can, individually, be very expensive. The importance of timely Blood Grouping and limitations of existing instrument platforms (ie: requiring significant manual intervention) also restricts the use of existing instrument platforms in smaller patient testing settings.

Disease Screening

Safety of donor blood is ultimately the responsibility of donor collection agencies, with regulatory agencies in individual countries having established various safeguards and standards in order to ensure patient safety. In the developed world, donor blood is subject to mandatory screening for infectious diseases before it can be released to hospitals. Two different testing methods of have been adopted a serological approach (testing for specific antigens or antibodies) and, for certain viruses, a molecular approach (testing for nucleic acid).

The United States, many Western European countries, and Japan require both serological and molecular disease screening be performed on donor blood. In the United States, it is also mandatory to screen donor blood using serological techniques for the following: Syphilis, Hepatitis B Surface Antigen, Hepatitis B Core Antibody, Hepatitis C Antibody, Human Immunodeficiency Viruses, or HIV, Type 1 and Type 2 Antibodies and Human T-Lymphotropic Antibodies. Most blood collection agencies will also screen for Cytomegalovirus, or CMV, using the same serological approach and the FDA recommends donor blood to be screened for Chagas disease. Molecular disease screening is required to be performed on donated blood to screen for Hepatitis B, Hepatitis C, HIV and West Nile virus. Other pathogens, such as Babesia Microti, Dengue and Malaria are transmissible by blood, but there is no test currently available, given cost or technology limitations.

Serological disease screening is already largely automated, with current testing typically performed on two separate instrument platforms offered by different vendors.

Donor & Patient Testing Environments

Quotient observes that blood grouping and disease screening techniques have remained generally unchanged for many years, with a handful of instrument platforms available for basic antigen typing, antibody screening and some additional antigen typing. However, significant manual intervention is still required to complete more complex blood grouping procedures, such as extended antigen typing and antibody identification. In many cases, it is also not possible to obtain a sufficient blood sample volume from patients (for example, from anemia patients and babies) for blood grouping using existing instrument platforms.

Limitations of Current Blood Grouping and Disease Screening Methods

A significant proportion of the overall cost of blood grouping is accounted for by the ongoing need for complex manual testing procedures. Additionally, with over 30 clinically significant blood-group antigens and antibodies to characterize, the required reagents for blood grouping (whether performed on instruments or manually) are both complex and extensive.

Quotient maintains that both donor collection agencies and hospitals would presumably prefer to fully characterize donor units through extended antigen typing prior to transfusion, although the time and expense required to undertake such procedures using current methods is generally prohibitive, and therefore extended antigen typing is only undertaken as needed (i.e., where the patient has a specific antibody) on a small percentage of donor units.

Limitations of existing blood grouping methods and instruments mean that extensive pre-transfusion antigen typing is not widely undertaken due to cost and complexity, resulting in more patients developing antibodies, which complicates future transfusions. Shortcomings of current screening methods and protocols include the requirement for highly trained laboratory technicians; extensive, complex and expensive reagent requirements — some with shelf lives under 30 days; supply shortages of licensed antisera for some rare, but clinically significant blood-group antigens; incremental supervision, technical training and quality assurance costs, given the lack of standardization resulting from complex manual testing procedures; potential for testing or labeling errors given the large manual component; lower red blood cell or plasma yields for donor collection agencies, given test volume requirements; difficulty testing patients that can provide only low volumes of blood samples, including anemia patients and babies; costly service and support infrastructure needed to maintain multiple instrument platforms in a donor testing environment; and inability of existing instrument platforms to connect to laboratory automation (or track-based) systems.

While serological disease screening is already largely automated, it is typically undertaken using two separate instrument platforms, neither of them integrated with commonly-used blood grouping instruments. Automation platforms for serological disease screening have been on the market for many years but lack the key attributes that users benefit from in other diagnostic fields such as user-interface, remote diagnostics, ability to link to laboratory automation systems and software compatibility with laboratory information systems. Additionally, existing disease screening platforms lack the ability to easily add additional tests as the market and regulators dictate.

The MosiaQ Solution

Quotient are developing MosaiQ to address the shortcomings of current methods outlined above and the comprehensive needs of the global transfusion diagnostics market. The company believes MosaiQ has potential to transform transfusion diagnostics by substantially reducing costs and offering a range of operational efficiencies within donor and patient testing laboratories, while improving patient outcomes through a more complete characterization of donor and patient blood.

Quotient explains that MosaiQ will comprise two separate consumables, one for blood grouping and one for serological disease screening, and initially, a high-throughput instrument. In donor testing environments, MosaiQ is designed to conduct both blood grouping and disease screening tests simultaneously, while only blood grouping would be performed in a patient testing environment. The MosaiQ blood grouping consumable will consist of two protein microarrays: one printed with red blood cells and the other printed with antibodies. Quotient’s novel approach incorporates existing, well-characterized tests for all clinically significant blood-group antigens and antibodies onto a single, multiplex consumable for the global market. Using the same approach, they say they plan to incorporate all currently mandated serological disease screening tests onto a second disease screening consumable. Both consumables are designed to be processed using the same MosaiQ high-throughput instrument.

Blood Grouping Consumable

The MosaiQ blood grouping consumable is designed to fully characterize donor and patient blood, identifying all clinically significant blood-group antigens and antibodies. Quotient believes MosaiQ, when launched, will be the only commercially available automation platform capable of offering this scope of testing.

Instrumentation

The MosaiQ instrument is designed to fully automate blood grouping and perform a simultaneous disease screen in a donor testing laboratory. Consistent with the typical workflow of donor or patient testing laboratories, centrifuged tubes of whole blood will be placed on the MosaiQ instrument for processing. The instrument will then complete a full blood group characterization of each blood sample, combined with a parallel disease screen in a donor testing environment, with the results being reported through existing laboratory information management systems (or LIMS).

Quotient is developing a high-throughput, floor standing MosaiQ instrument for use by both donor collection agencies and medium to large-sized hospitals. This initial MosaiQ instrument is being designed to process 900 to 1,000 consumables per eight-hour shift, giving a capacity to test 450 to 500 donor samples (utilizing a blood-grouping consumable and a disease screening consumable) or 900 to 1,000 patient samples (blood grouping only).

MosaiQ Advantages

Quotient expects use of MosaiQ for blood grouping and disease screening will offer both major cost saving opportunities and clinical benefits, including:

Improved clinical decision making and better matching of donor and patient blood, with the potential to reduce the incidence of alloimmunization;
Extended antigen typing for all donor blood;
Comprehensive antibody identification, eliminating the need for an antibody screen and expensive manual testing;
Significantly reduced need for complex, manual testing procedures, delivering major workflow efficiencies;
Standardization of blood grouping, reducing the potential for testing or labeling errors;
Consolidation of multiple instrument platforms and complicated manual testing procedures onto a single automated instrument;
Significantly simplified consumable requirements, with one consumable for blood grouping and one consumable for disease screening;
Substantially improved time to result for complex blood grouping procedures, such as antibody identification and extended antigen typing;
Significantly lower donor testing volume requirements, increasing plasma and red blood cell yields per donation;
Lower patient sample volume requirements, potentially eliminating the need for manual testing where sufficient sample volume proves difficult to obtain (for example, from babies and patients suffering from anemia);
Significantly increased shelf life for red blood cell-derived tests;
Reduced consumable waste;
Lower sample logistics costs;
Potential to electronically match donor and patient blood; and
Ability to integrate onto existing laboratory automation (track-based) systems.