Serum Free Light Chain Assays

diagnosis and treatment of multiple myeloma? n Can the Freelite" test be used to assess response to treatment? This booklet is meant to provide you with general information only.<br><br> It is not meant to replace the advice of your doctor or nurse. Your doctor or nurse can answer questions related to your specific treatment plan. The definitions of all words in italics are found in the glossary at the end of this booklet.<br><br> myeloma. The free light chains are derived from the monoclonal protein (See Figure 1). What are Free Light Chains?<br><br> Immunoglobulins or monoclonal proteins are composed of two types of smaller molecules, one called a heavy chain and the other called a light chain (see Figure 1). There are five types of heavy chains, referred to by letter, with the abbreviation for immu- noglobulin (Ig) before the letter: IgG, IgA, IgM, IgD, and IgE. There are two types of light chains, referred to as kappa ( º ) and lambda ( » ).<br><br> Each plasma cell produces only one type of heavy chain and only one type of light chain. The heavy and light chains are produced sep- arately within the plasma cell and are then assembled to form a whole immunoglobulin. When the light chains are attached to the heavy chains, the light chains are referred to as bound light chains.<br><br> However, when the light chains are not attached to the heavy chains, they are called free light chains. For unknown reasons, the plasma cells typically produce more light chains than are required to create the whole immunoglobulin or mono- clonal protein. The excess light chains enter the blood stream as free light chains (i.e.<br><br> unattached to the heavy chains). Thus both in the normal situation and in patients with myeloma and monoclonal gammopathies (e.g. MGUS, or monoclonal gammopathy of undetermined significance), excess light 6 7 Multiple Myeloma and Monoclonal Protein Myeloma is a cancer of the plasma cells in the bone marrow.<br><br> Myeloma is synonymous with multiple myeloma and plasma cell. neoplasm. Plasma cells produce antibodies , also known as immunoglobulins, which are proteins that help fight infection.<br><br> Each type of plasma cell produces only one type of immunoglobulin. There are many different types of plasma cells in the body, resulting in the production of a variety of different immunoglobulins. In multiple myeloma, one particular type of plasma cell is duplicated a very large number of times, causing excess production of one type of immunoglobulin, which is referred to as a monoclonal pro- tein, or M-protein .<br><br> M-protein is also called myeloma protein, para-protein, or the protein spike. M-protein is important for diagnosis and for monitoring treatment in multiple Figure 1. Structure of an immunoglobulin or monoclonal protein is present in increased amounts.<br><br> But excess light chains in the serum can also occur to a greater or lesser extent with all types of myeloma, not just light chain or Bence Jones myeloma. How is Monoclonal Protein Normally Detected and Measured? Monoclonal proteins can be detected and measured in both blood and urine.<br><br> Serum is merely blood that has had the cells removed, leaving only the clear liquid. If multiple myeloma is suspected, your doctor will screen for abnormal monoclonal protein (M-protein) levels using a laboratory test known as protein electrophoresis. When pro- tein electrophoresis is performed on serum samples, it is referred to as serum protein electrophoresis (SPEP), and when performed on urine samples, it is called urine protein electrophoresis (UPEP).<br><br> SPEP and UPEP can 9 chains enter the blood stream as free light chains. The normal levels of free light chains in serum have recently been reported, along with the normal ratio of kappa free light chains to lambda free light chains. Normal levels of kappa free light chains are between 3.3 and 19.4 mg/L, while normal levels of lambda free light chains are between 5.71 and 26.3 mg/L.<br><br> The kappa/lambda ratio, which is normally between 0.26 and 1.65, is as important for diagnosis and monitoring of myeloma as are the levels of kappa and lambda light chains. As one might suspect in patients with active myeloma, the free light chain levels are higher than normal. In patients with myeloma in which only light chains are produced (Bence Jones myeloma), the type of light chain corresponding to the type of myeloma, either kappa or lambda, 8 Figure 2.<br><br> Illustrates SPEP (above left), UPEP (below left), and their respective IFEs (right). alb ±1±2² alb ±1±2² SPE l lgG 2 lgA 3 lgM 4 º 5 1 2 3 4 5 6 7 1 2 3 4 5 6 7 » 6 SPE l lgG 2 lgA 3 lgM 4 º 5 » 6 would have to be at least 50 times the normal level to be detected by SPEP, and at least 15 times the normal level to be detected by IFE. An alternative test method, the serum free light chain assay, is capable of detecting free light chains at their normal levels in blood serum.<br><br> Thus, the serum free light chain assays can detect elevated levels of free light chains, even when these levels are unde- tectable by SPEP and IFE. This means that multiple myeloma could be detected earlier in the course of disease than is possible with either SPEP or IFE or in cases where small amounts of light chains are produced by the myeloma. The free light chain assays are best per- formed on serum rather than urine because of the filtering effects of the kidneys.<br><br> Part of the normal function of the kidneys is to prevent losing proteins from the body into urine. As a result, an elevated level of a protein, such as M-protein, will be present in blood serum before being present in urine. Hence, the serum free light chain assays may completely replace the 24-hour urine tests for M-protein: not only are the free light chain assays more sensitive in serum, but a 24- hour urine sample is difficult to collect and is more difficult to store than serum.<br><br> Like other assays to detect M-protein, the serum free light chain assays have both advantages and disadvantages. As dis- cussed above, one advantage is greater sensitivity than is available with SPEP, UPEP, 11 measure the amount of M-protein in a sam- ple, but cannot identify the type of M-protein in the sample. A second type of electro- phoresis test, referred to as immunofixation electrophoresis (IFE), is performed in order to identify the type of M-protein that is being produced by the myeloma cells.<br><br> Typically, an SPEP is performed first, to determine if, and how much, of an M-protein is present. If the SPEP demonstrates evidence of an M-protein, an IFE will be done to determine what type of M-protein is there. SPEP, UPEP, and IFE have both advantages and disadvantages.<br><br> Among the disadvan- tages is that they are relatively insensitive for the detection of free light chains, in that the free light chain level must typically be many times the normal level in order to be detected. For instance, the normal level of one type of free light chain in blood is approximately 10 milligrams per liter (abbreviated as mg/L). However, the free light chain level in blood 10 and IFE.<br><br> Another advantage is that the serum free light chain assays are automated and require less time to perform than do SPEP, UPEP, and IFE. However, although the serum free light chain assays are excellent for detec- tion of free light chain immunoglobulins, they are unable to detect whole immunoglobulins. Some myeloma patients secrete only whole immunoglobulins.<br><br> Therefore, it is best to per- form both SPEP (to detect elevated levels of whole immunoglobulins) and the serum free light chain assays (to detect free light chains) in combination. How Can the Serum Free Light Chain Assays Help with Diagnosis and Treatment? Serum free light chain assays can help in three ways: 1.<br><br> Monitoring patients with low levels of myeloma protein (M-component) Patients with low levels of M-component are called non-secretory or hypo secretory. Approximately 70-80% of such patients have light chains that are measurable by the free light chain assay test. Guidelines have been established to assess response to treatment using the Freelite" test (See Table 1 below).<br><br> Since the Freelite" test has been introduced only within the last two years, most hematol- ogy/oncology groups are just learning fully about the test and establishing their own procedures. Specialist consultation may be 12 required for full interpretation and/or assess- ment of the monitored results. The major concept to keep in mind is that myeloma is a monoclonal disease.<br><br> Thus the light chains produced by the myeloma cells will be exclu- sively free kappa or free lambda, depending upon the type of the myeloma. The production of one type of light chain, but not the other, will result in an abnor- mal kappa/lambda ratio, which is normally between 0.26 and 1.65. If the level of kappa free light chains is too high, while the level of lambda free light chains is either normal or low, the kappa/lambda ratio will be higher 13 to treatment occur rapidly.<br><br> Thus if a patient is responding well to treatment, the free light chain level will drop within a few days. This is much faster than IgG or IgA drops, because these larger molecules are broken down much more slowly by the body. Increases in free light chain levels can thus be a very sensitive indicator of early response.<br><br> Studies are ongoing to assess the reliability of using free light chain measurements in this way to track early response. At the time of relapse, the sensitivity of the free light chain assay becomes most signifi- cant. Even very small amounts of myeloma that start to grow as part of relapse produce measurable amounts of free light chains.<br><br> Studies are ongoing to compare the sensitiv- ity of FDG-PET or CT-PET scanning versus free light chain measurements in detecting very early relapse. 3. Free light chain level as an indicator of disease activity A recent study from the Mayo Clinic has shown that patients with MGUS who also have elevated levels of free light chains in the blood are more likely to progress and develop active myeloma.<br><br> Freelite" is therefore a useful test in that setting. In addi- tion, early studies suggest that changes in Freelite" levels may be useful in tracking the disease status for myeloma patients overall, not just those with Bence Jones (light chain) myeloma or non-secretory disease. Further clinical trials are needed to clarify the use of 14 15 than normal (higher than 1.65).<br><br> If, on the other hand, the concentration of lambda free light chains is too high, but the kappa free light chain level is normal or low, the kappa/ lambda ratio will be lower than normal (less than 0.26). If levels of both kappa and lambda light chains are elevated, resulting in a ratio that is within the normal range, then this indicates a disease other than myeloma, such as impairment of kidney function. 2.<br><br> Evaluation of early response and early relapse Since serum free light chains are broken down and/or excreted by the kidneys rather quickly, changes in blood levels in response IFE. Typically, responses to treatment can be detected by serum free light chain assays in a matter of one or two days, whereas it may take one to three weeks to detect responses using SPEP and IFE. In some cases, response to treatment can be detected by the serum free light chain assays in a matter of hours.<br><br> Lastly, the serum free light chain assays may afford the ability to identify relapse earlier than may be the case with other tests. Part of the definition of complete remission is that the M-protein not be detected by IFE. However, as discussed above, the serum free light chain assays are more sensitive in the detection of light chains than is IFE.<br><br> Hence, the serum free light chain assays can often detect an increase in free light chain levels before the increase can be detected by IFE. 17 Freelite" in myeloma patients throughout the disease course. The kappa/lambda Ratio n The importance of the kappa/lambda ratio is not immediately obvious.<br><br> n When the levels of abnormal kappa or lambda are very high, then obviously the ratio is very abnormal. n However, if the levels of both the abnormal light chain (e.g. kappa) and the other light chain (e.g.<br><br> lambda) are both elevated, then the ratio may be normal. This indi- cates that the levels are elevated because of poor kidney function resulting in reten- tion of both types of light chains within the blood stream. This is therefore not in itself a direct result of currently active myeloma.<br><br> n Conversely, if the kappa and lambda lev- els are both within the normal range, the ratio may continue to be abnormal. This indicates that there is indeed a persistent low level of active myeloma with excess production of the abnormal light chain. If the ratio also becomes normal, this reflects an especially good remission and corre- lates with possible longer remission.<br><br> Monitoring treatment can be greatly facilitated by the use of serum free light chain assays. The reason for this is that the serum free light chain assays can reveal responses to treatment well before they can be detected using SPEP and 16 19 Freelite " Levels and the Assessment of Response to Treatment Serum Freelite " levels can be used in the same way as monoclonal protein mea- surements to assess response to treatment. Recently, specific criteria have been estab- lished and are summarized in Table 1.<br><br> Table 1 . Freelite: Guidelines for Response Criteria *The normal range for the ratio has been expanded slightly to encompass patients with renal insufficiency. **If the Freelite level is < 100 mg/L, then no partial response assessment is possible.<br><br> COMPLETE RESPONSE n Reduction of kappa/lambda ratio to normal range* of: 0.26-2.0 n IFE negative serum and urine PARTIAL RESPONSE n Baseline FREELITE must be e 100 mg/L** n e 50% decrease in FREELITE level These response criteria are being inte- grated into previously published Myeloma Management Guidelines (see IMF publica- tions). In summary, the serum free light chain assays offer several advantages for diagnosis and monitoring of treatment: n Inclusion of serum free light chain assays can improve the sensitivity of screening protocols for detection and diagnosis of myeloma. 18 n Serum free light chain assays, along with other laboratory tests, can provide valu- able information on prognosis of MGUS patients.<br><br> n Use of serum free light chain assays to monitor treatment reveals responses to treatment more rapidly than do other labo- ratory tests. n The improved sensitivity of serum free light chain assays over IFE may allow earlier detection of a relapse of myeloma. Patients Who Can Benefit the Most from Serum Free Light Chain Assays are: n Patients with very low levels of light chains with other tests such as SPEP, UPEP or IFE.<br><br> Such patients are often called non-secre- tory. Approximately 80% of such patients can be successfully monitored using serum free light chain assays. n Patients with deposits of light chains in the form of amyloidosis.<br><br> Amyloidosis patients may or may not have active myeloma. Tracking the light chain levels is very help- ful to assess the disease status. n Patients with light chain only myeloma (Bence-Jones myeloma).<br><br> The major advan- tages for these patients are: " Ease of blood testing versus 24-hour urine collection " The much greater sensitivity of the blood testing, i.e. low levels detected in the blood, but not picked up in the urine. Will Insurance Cover the Cost of Serum Free Light Chain Assays?<br><br> The serum free light chain assays are reim- bursed by Medicare. Please consult with your doctor and insurance provider regard- ing this issue. About the IMF cOne person can make a difference, Two can make a miracle. d Brian D.<br><br> Novis IMF Founder Myeloma is a little-known, complex, and often misdiagnosed bone marrow cancer that attacks and destroys bone. Myeloma affects approximately 75,000 to 100,000 people in the United States, with more than 15,000 new cases diagnosed each year. While there is presently no known cure for myeloma, doctors have many approaches to help myeloma patients live better and longer.<br><br> The International Myeloma Foundation (IMF) was founded in 1990 by Brian and Susie Novis shortly after Brian 9s myeloma diagno- sis at the age of 33. It was Brian 9s dream that future patients would have easy access to medical information and emotional support throughout their battle with myeloma. He established the IMF with the 3 goals of treat- ment, education, and research.<br><br> He sought to provide a broad spectrum of services for patients, their families, friends, and health care providers. Although Brian died 4 years after his initial diagnosis, his dream didn 9t. Today the IMF reaches out to an international membership of more than 125,000.<br><br> The IMF was the first organization dedicated solely to myeloma, and today it remains the largest. 22 23 The IMF provides programs and services to aid in the research, diagnosis, treatment, and management of myeloma. The IMF ensures that no one must brave the myeloma battle alone.<br><br> We care for patients today, while working toward tomorrow 9s cure. How Can the IMF Help You? PATIENT EDUCATION INFORMATION PACKAGE Our free IMF InfoPack provides comprehensive information about myeloma, treatment options, disease management, and IMF services.<br><br> It includes our acclaimed Patient Handbook . INTERNET ACCESS Log on to www.myeloma.org for 24-hour access to information about myeloma, the IMF, education, and support programs. ONLINE MYELOMA FORUM Join the IMF Internet Discussion Group at www.myeloma.org/listserve.html to share your thoughts and experiences.<br><br> MYELOMA MINUTE Subscribe to this free weekly email news- letter for up-to-the-minute information about myeloma. PATIENT & FAMILY SEMINARS Meet with leading experts in myeloma treat- ment to learn more about recent advances in therapy and research. MYELOMA MATRIX On our website and in print, this document is a comprehensive guide to drugs in development for myeloma.<br><br> MYELOMA TODAY NEWSLETTER Our quarterly newsletter is available free of charge by subscription. SUPPORT MYELOMA HOTLINE: 800-452-CURE (2873) Toll-free throughout the United States and Canada, the IMF Hotline is staffed by trained information specialists and is in frequent inter- action with members of our Scientific Advisory Board. SUPPORT GROUPS A worldwide network of more than 100 myelo- ma support groups hold regular meetings for members of the myeloma community.<br><br> The IMF conducts annual retreats for myeloma support group leaders. RESEARCH BANK ON A CURE ® This DNA bank will provide genetic data research in new drug development. THE INTERNATIONAL STAGING SYSTEM (ISS) This updated staging system for myeloma will enhance physicians 9 ability to select the most appropriate treatment for each patient.<br><br> RESEARCH GRANTS Leading the world in collaborative research and achieving extraordinary results, the IMF Grant Program supports both junior and senior researchers working on a broad spectrum of projects. The IMF has attracted many young investigators into the field of myeloma, and they have remained in the field and are actively pursuing a cure for this disease. 22 23 24 Glossary Antibody: A protein produced by plasma cells (a type of white blood cell) which helps fight infection.<br><br> Also known as an immunoglobulin. Antigen: A substance that when introduced into the body stimulates the production of an antibody. Antigens include bacteria, viruses, fungi, toxins, foreign blood cells, and the cells of transplanted organs.<br><br> Bone marrow : A soft, spongy tissue found in most large bones that produces red and white blood cells and platelets. Cell: The smallest unit of life. Millions of microscopic cells comprise each bodily organ.<br><br> Immunoglobulin: See cAntibody. d Monoclonal protein (M-protein): An abnormal protein pro- duced by myeloma cells which accumulates in and dam- ages bone marrow. A high level of M-protein indicates that myeloma cells are present in large numbers. Appointments Kappa Lambda º / » Date Time Important Notes Level Level Ratio Multiple myeloma: A cancer arising from the plasma cells in the bone marrow.<br><br> The plasma cells in patients with multiple myeloma form abnormal antibodies, possibly damaging the bone, bone marrow, and other organs. Plasma cell: A type of white blood cell that produces antibodies. Plasmacytoma: A tumor made up of cancerous plasma cells.<br><br> Protein: A group of compounds that are the main compo- nents of a cell. Red blood cell: A blood cell that carries oxygen from the lungs throughout the body. White blood cell: A cell made by the bone marrow that helps fight infection and/or disease.<br><br> 25 Appointments Kappa Lambda º / » Date Time Important Notes Level Level Ratio

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