Updated: August 29, 2007
FISHing in Murky Waters
The Risk of Undetected FISH Defects
The Importance of Asking the Meaningful Question
The typical commercially available FISH panel contains four probes which seek to establish the presence or absence of the most common cytogenetic abnormalities in CLL. Results that do not have one of these four common deletions or mutations are labeled “normal” — a misleading label. CLL cells almost certainly suffer from some genetic abnormality that makes them cancer cells to begin with. Even for those patients who have one or more of the known defects, the limited probe set could mask additional defects that may have a bearing on risk assessment and treatment. In FISHing in Murky Waters, we examine the importance of expanding the probe set presently used in the standard CLL FISH panel.
MCL — a Wolf in CLL Clothing
Accurate Diagnosis Leads to Better Treatment
Know the Name of Your Enemy
FISH analysis is one of the key prognostic tests used to identify the type of CLL a patient has. However, the usual FISH panels contain probes for only the most common cytogenetic abnormalities. Rarer aberrations all get lumped together in a basket labeled "normal". In this article, MCL - a Wolf in CLL Clothing, we examine how a probe for one such rare aberration, the t(11:14) translocation, can yield valuable information in distinguishing CLL from the more aggressive Mantle Cell Lymphoma, for which treatment choices are not the same. Having this additional probe included in your FISH test may well depend upon your negotiating skills.
Prognostic and Monitoring Tests
Test Packages are Now Available
Quest Diagnostics Is First to the Table
Your doctor can now order a package of CLL-specific prognostic tests from the largest company in the medical test industry, Quest Diagnostics, Inc. Doctors can now get the tests done as a package deal — and at a reasonable cost to the patient. It has been our crusade to take out some of the road blocks to make prognostic testing accessible to local healthcare providers who guide the therapy choices of their CLL patients every day. Read about this important and very useful development in our article on Prognostic and Monitoring Tests. We provide all the details of how to get the tests done and the logic you may need to convince your doctor to order them.
Getting It Done
Progress in Getting the Tests Made Accessible
Our Quest For Solutions
The value of getting the right prognostic tests done is slowly gaining acceptance in the patient community. However, the practical difficulties involved are numerous and each patient has to deal with his or her providers as well as he or she can. In this article, Progress on Prognostics, we review our own progress in de-tangling the logistical and communication nightmare for the patient community. In CLL, as in life, what you get is what you negotiate - and we have been busy.
ZAP-70 & IgVH Gene Mutation Status
Two Prognostic Indicators Worth Understanding
We Compare the Value of These Indicators in Identifying a Patient's Risk Category
These two indicators, in combination with FISH analysis to pinpoint the chromosomal aberration that is at the root of the CLL, go a long way toward defining the risk category of a given patient. In ZAP-70 and IgVH Gene Mutation we review the current research on the prognostic value of these two important tests.
FISH-ing for Answers
Chromosomal Aberrations Rule the Game
The Importance of Cytogenetics — and Some Practical Information on Getting Your FISH Test Done
FISH (fluorescence in-situ hybridization) testing can provide key information to CLL patients and their doctors in making therapy decisions. In FISH-ing for Answers we provide some critical information that may be useful in getting your very own FISH test done.
Prognosis at Diagnosis
Advice from Mayo Clinic on Using Modern Tools
Integrating Molecular Biologic Insights into Clinical Practice
We examine a critically important new Blood First Edition Paper - pre-published online. Read Prognosis at Diagnosis, our review of this article from the experts at Mayo Clinic. While much of the research quoted in this article has been previously reported, this article will nevertheless be important. In Chaya's opinion, “What makes this paper unique is that it puts it all together in one irrefutable package: the research, the results, the logic, the recommendations. I have no doubt this paper will be one of the most influential papers in CLL, and will be influencing clinical practice for many years to come.”
The Invention of Buckets
What Type of CLL Do You Have?
In this article, we review the literature categorizing the aggressivness of various strains of CLL and their resistance to therapy. Based on a reading of the available literature on prognostic indicators, we identify risk "buckets" to describe patients' prospects. It is increasingly evident that risk categorizaiton rather than staging will indicate the likelihood of disease progression for a given patient. To learn more about your prospects, you might want to ask What Type of CLL Do You Have? An answer to that question might leave you better prepared to deal with the issues you may face.
Risk and Progression Rate Bear on Therapy Choices
IgVH Gene Mutation Status and CD38 Expression
This article, IgVH Gene Mutation Status and CD38 Expression as Prognostic Indicators in CLL, is about recent and extremely important findings in our understanding of CLL and how to make the right therapy decisions for patients with potentially very different prognoses.
A Stable and Indolent Phenotype
by Chaya Venkat
We have discussed various prognostic indicators in previous articles: B2M, lymphocyte doubling time, CD38 expression on CLL cells, IgVH gene mutation status, and most recently, ZAP-70 expression. Below is an abstract from the latest issue of Blood that pulls it all together. Here are some CLL patients that were monitored for as long as 23 years, who never needed treatment for their cancer, no major infections and no pesky autoimmune diseases of any kind.
The idea is not for you to go into a tailspin if you are newly diagnosed, and you don't fit this perfect picture of CLL “smolderer”. The last sentence or two of this abstract are the most important ones, in my opinion. There are so many new therapeutic developments, some of them quite aggressive, it would be a shame to put your old bod through all that pain and suffering, not to mention toxicity, if you did not need it in the first place. And, the other side of the coin, it is better to know how your particular flavor of CLL stacks up, so that you can make smart therapy choices and not let it get out of hand.
How will you be able to make the right choices if you do not have a decent handle on the prognosis? At the risk of irritating a few of our new friends, I will repeat myself: in this disease, what you don't know can truly kill you. If there is one thing we can do as a patient group, in my opinion it would be to gear up for strong advocacy efforts, get some of these tests standardized and into commercial labs so that they are available and routinely used for new patients.
Blood. 2003 Apr 3 [Epub ahead of print].
Chronic lymphocytic leukemia patients with highly stable and indolent disease show distinctive phenotypic and genotypic features.
Guarini A, Gaidano G, Mauro FR, Capello D, Mancini F, De Propris MS, Mancini M, Orsini E, Gentile M, Breccia M, Cuneo A, Castoldi G, Foa R.
Dipartimento di Biotecnologie Cellulari ed Ematologia, Universita 'La Sapienza', Rome, Italy.
Different biologic features have been associated with a more or less aggressive clinical course in chronic lymphocytic leukemia (CLL). In the present study, 20 patients with highly stable CLL observed at a single institution over a period of 10-23 years and who never required treatment have been extensively characterized. The aim was to identify a distinct and reproducible biologic profile associated with disease stability that may be utilized to recognize at presentation CLL patients who are likely to have a very benign clinical course and for whom treatment is not indicated. The results obtained indicate that numerous parameters are closely associated with disease stability: a typical CLL morphology and immunophenotype, the lack of expression of the CD38 antigen, the mutated IgVH pattern, the absence of p53 mutations, a CD4/CD8 ratio >1, the lack of 17p and 11q deletions, as well as of complex karyotypic aberrations, and the occurrence of the 13q14 deletion. No case displayed the VH3-21 gene that has been linked in mutated CLL with a poor outcome. In addition, the VH1-69 gene associated with unmutated CLL cases was never detected. These biologic features were coupled with an indolent clinical course characterized by an unmodified clinical stage from diagnosis to the time of this study, lack of autoimmune phenomena and of major infections requiring parental antibiotics. At a time when aggressive therapeutic strategies are always more frequently being utilized in the management of CLL, the distinctive features of patients with long- lived stable disease should be prospectively identified at presentation.
Good Prognostic Indicators Do Not Guarantee Therapy-Free Life
by Chaya Venkat
A member of the CLL Topics group noted that even for the ZAP-70 negative (mutated) subgroup, 40% needed treatment within ten years of initial diagnosis. To her, this meant that a mutated status is no guarantee of a 'walk in the park'. She concluded that perhaps individuals with this type of CLL would require less treatment and that treatment might possibly be more effective. It also seemed possible to her that even patients who had been treated could have the mutated status and such testing might produce some insight into their best treatment options.
Of course this member is absolutely right. The only people who are 100% guaranteed never to need treatment for CLL are the people who do not have CLL in the first place, and don't get it down the road. For the rest of us unfortunate enough to have this disease, it is a question of statistics and odds, not individual guarantees.
I would like you to consider one of our patient members, "Sam". Here is a patient who was fortunate enough to have been able to get testing done for IgVH gene mutation status, not just the ZAP-70 test which we hope is a good proxy for the real thing. "Sam" (not his real name) is fortunate in that he has the good mutated IgVH gene, he also has low CD38, low B2M, good nutrition, exercise, the works. All of this information is on his chart, you can look it up. Poster child for the good prognosis group, right? And yes, he has had very indolent and smooth progression of his CLL, no health problems thus far, and no therapy yet. All of which is good.
But nevertheless Sam's CLL is progressing, the WBC keeps climbing, smoothly upwards, and most recently, there is a hint of dropping platelet levels. Nothing to worry about yet, but at some point, he will probably require therapy. Sam is a relatively young man now, I think there is no chance he will go into ripe old age without ever requiring therapy for his CLL.
If you are unfortunate enough to have CLL, there is no question about it, it is better to have Sam's version of CLL than a much more aggressive form that is beset with dangerous health problems from the start, requires and responds poorly to therapy and adds up to a reduced quality and quantity of life.
Prognostic indicators are not guarantees you can take to the bank. They provide information on which you can base more realistic decisions, hopefully more effective therapy choices, both in terms of timing and level of aggressiveness.
ZAP-70: Breakthrough Prognostic Indicator?
by Chaya Venkat
None of us know how long we are going to live, the only thing certain in this world is death (and taxes!). But CLL patients and their families have to bear the additional burden of constant awareness of their mortality.
What makes this disease a real mind game is the tantalizing nature of the diagnosis: it is an indolent disease, some people live out their natural life spans never needing any treatment at all! May be you will be one of the lucky ones? What if you are not? How to make every day life decisions, with this sword hanging over our heads? Should you go ahead and have that baby you were thinking of having? Would that be irresponsible, if you are not likely to be there to see the kid to adulthood? How about changing jobs or going back to school, would it be life threatening to have less than perfect health insurance for a couple of years? Can you go on that cruise with your sweetheart, or should you hunker down and avoid even remote chances of picking up an infection? Are you going to live a nice long life without having to do much of anything, or should you get ready to bring out the big guns to try and slay this dragon before it kills you? If you spend the next year waiting for an experimental therapy that does not pan out, would you have shot yourself in the foot (or higher up) in terms of time wasted, that perhaps kicks your CLL into advanced stage? Would you rather know your chances upfront, or would you just like to take it as it comes, one day at a time?
These and a million more questions plague each of us, as we face an uncertain future. At this stage, CLL is still an "incurable" cancer. I am optimistic that definition will change within our lifetimes. One of our members wrote recently about the poignancy of missed opportunities, of new therapies coming on line too late to be of much help to some of the 'old timers' who have been fighting this disease for a long time. True, and how much sadder it would be if the opportunities are here already, but missed because of poor therapy choices, because of lack of information. Besides an actual cure for CLL, the single other area of crucial interest to all of us is accurate and dependable prognosis. This chess game of move and countermove is hard to win if patients are making therapy choices in the dark.
The first URL at the bottom of this article will take you to the review of prognostic indicators on our website. The next few URLs will take you to some of the most important papers published in the last year or two on the subject of IgVH gene mutation status, CD38 expression, genetic abnormalities. If you are a newly diagnosed patient, read our website discussion, then the original papers. You really need to know this stuff.
The issue is this: there is almost universal agreement that CLL patients can be divided roughly into two categories, one bunch who will have very slow moving disease that will not require therapy for a long time, if ever, and the other not so lucky group that have an aggressive version of the disease, and majority of this group will require therapy sooner rather than later. Over the last couple of years, evidence has accumulated from a number of different labs confirming that the distinguishing feature between the two groups is their IgVH gene mutation status. Patients with mutated IgVH gene had far better survival prognosis than those that did not. One study showed that half the patients with mutated IgVH gene were still alive 25 years or longer (i.e., their survival statistics was no different than age and sex matched "normal" folks who did not have CLL), while half of the patients with unmutated IgVH gene were dead by 6-10 years. Quite a difference, enough to swing quite a few therapy and life choices one way or the other.
Since it is very difficult to do the IgVH sequencing in anything other than an expert research lab, the search was on for another more readily available indicator that paralleled the IgVH gene mutation status. CD38 expression on CLL cells was suggested as a possible surrogate, something that can be done by labs capable of doing quantitative flow cytometry. While some researchers saw a good degree of correlation between IgVH gene mutation status and CD38 expression, others did not see sufficient correlation, so the search continued for a better choice than CD38 expression. Another problem is that CD38 expression was thought to change over a period of time, and there may in fact be several distinct sub-populations of CLL cells within the same patient, with different CD38 expression. With that as background, lets discuss the two very recent papers on ZAP-70, one in the New England Journal of Medicine and the other in Blood.
The Blood article is older (February 20, 2003), so I guess we discuss it first. The authors are top drawer, including Gerald Marti of FDA, Terry Hamblin of IgVH gene mutation fame, and Louis Staudt of National Cancer Institute. Certainly a crowd whose opinions carry a lot of weight in CLL arena.
The second and more recent paper (by a few months, this one is dated May 1, 2003) on ZAP-70 in the prestigious New England Journal of Medicine has an equally impressive line up of authors, not the least of whom is Dr. Emili Montserrat. Almost as valuable is the editorial in the same issue of NEJM on the ZAP-70 paper by Dr. Kanti Rai, et al.
This paper covers some of the same ground as the article in Blood and I will skip those portions. On careful reading, there are some very interesting nuggets of information:
And here is a quote from Dr. Rai's editorial of this paper:
"We can expect that the newly recognized prognostic markers and their surrogates will soon allow physicians to offer individual patients with CLL a much more definitive projection of their clinical course than is currently possible. Moreover, it seems reasonable to hope that, in the not-too-distant future, molecular insights into the pathogenesis of CLL will begin to provide new and effective therapeutic options that are superior to today's all-too-frequent prescription of "watchful waiting."
Terry Hamblin's pivotal paper correlates IgVH gene mutation status with survival and prognosis for CLL patients - Blood Journal Article.
Rajendra Damle's paper suggests a correlation between level of CD38 expression on CLL cells (CD19/CD5/CD38 positive cells) and IgVH gene mutation status - Blood Journal Article.
Topics article, Genetic Abnormalities in Blood Cancers discussing the genetic abnormalities usually found in CLL
ZAP-70: A Valuable Prognostic Indicator
by Chaya Venkat
Two pivotal articles on the value of Zap-70 as a prognostic indicator in CLL, within a couple of months of each other, one in the prestigious Blood magazine and the other in the equally well regarded New England Journal of Medicine! Sit up and take notice folks. I don't think it is possible to over-state the importance of these two papers on how CLL patients will be diagnosed and treated in the future.
The abstracts of both articles are attached below. URLs for both abstracts are provided in the article that follows.
We should know by now that CLL comes in many flavors, and therapy choices need to be made in the context of the particular sub-type of the disease one is dealing with. It would be foolish to treat the true smoldering variety with aggressive chemotherapy, where the cure may indeed be more dangerous than the disease. Conversely, it is dangerous to wait too long to treat a more active CLL that is progressing rapidly. Therapy choices become more restricted and less likely to give optimum results once the bone marrow is heavily infiltrated, production of other cell lines is compromised and secondary problems such as autoimmune anemia and thrombocytopenia have gained a foothold.
Empirical observation over several decades has left little doubt that there are such two very different sub-groups classified under the catch-all name of CLL. There has been a great deal of work done to find a good prognostic indicator (or group of indicators) that can distinguish between the two groups. We are familiar with the old standards, lymphocyte doubling time, beta-2-microglobulin, sCD23 expression, bone marrow infiltration and diffuse versus nodular types of infiltration, and others. These and the rules developed for classification of the Rai and/or Binet stages of the disease have been useful. More recently, Dr. Hamblin and his colleagues have made an important discovery in this area: namely patients with mutated IgVH gene had a much, much better prognosis than those that had an unmutated IgVH gene. About the same time, Dr. Damle et al showed that CD38 expression on CLL cells was a good indicator of progression, people with 30% or higher CD38 expression had a poorer prognosis than those that had a lower level of CD38 on CLL cells. For a while there was some hope that both IgVH gene mutation status and CD38 expression correlated with each other, because while it was relatively easy to measure the CD38 expression on CLL cells, IgVH gene mutation status could only be done by the best equipped research labs, out of reach of general oncologists or their patients. It is now becoming clearer that while CD38 expression and IgVH gene mutation status track each other to some extent, the correlation between the two is far from perfect. The hunt continued for a better indicator.
Incidentally, if you are new to this area of research or would like to have a refresher course, we have several good articles on the subject of IgVH gene mutation and CD38. Please see the first two items in this section.
ZAP-70 seems to be the elusive answer we were looking for. It has all the necessary requirements for a practical and useful prognostic indicator. It has an impressive level of correlation with IgVH gene mutation status, and any lab capable of doing quantitative flow cytometry should be able to test for this marker. Testing for this marker should become routine in a little while. As proactive patients, we can help bring focus to this by asking for this test.
The New England Journal of Medicine
Volume 348, Issue 18: May 1, 2003
Marta Crespo, B.S., Francesc Bosch, M.D., Neus Villamor, M.D., Beatriz Bellosillo, Ph.D., Dolors Colomer, Ph.D., María Rozman, M.D., Silvia Marcé, B.S., Armando López-Guillermo, M.D., Elies Campo, M.D., and Emili Montserrat, M.D.
ZAP-70 Expression and Prognosis in Chronic Lymphocytic Leukemia
Mutations of immunoglobulin genes in chronic-lymphocytic-leukemia (CLL) cells augur a good outcome, whereas the absence of mutations indicates a poor prognosis. The presence of ZAP-70 on CLL cells correlated with unmutated immunoglobulin genes and a poor prognosis, whereas its absence indicated the presence of mutated genes and a good outcome.
Discovery of the prognostic importance of immunoglobulin-chain mutations, a major advance in CLL, has been slow to change clinical practice, because finding mutations is complex and expensive. However, any laboratory with a flow cytometer can measure ZAP-70.
Blood First Edition Paper, pre-published online February 20, 2003; DOI 10.1182/blood-2002-10-3306
ZAP-70 expression identifies a chronic lymphocytic leukemia subtype with unmutated immunoglobulin genes, inferior clinical outcome and distinct gene expression profile
Adrian Wiestner1,2, Andreas Rosenwald1, Todd S. Barry3, George Wright4, R. Eric Davis1, Sarah E. Henrickson1, Hong Zhao1, Rachel E. Ibbotson5, Jenny A. Orchard5, Zadie Davis5, Maryalice Stetler-Stevenson3, Mark Raffeld3, Diane C. Arthur3, Gerald. E. Marti6, Wyndham H. Wilson7, Terry J. Hamblin5, David G. Oscier5 and Louis M. Staudt1
The presence or absence of somatic mutations in the expressed immunoglobulin heavy chain variable regions (IgVH) of chronic lymphocytic leukemia (CLL) cells provides prognostic information. Patients whose leukemic cells express unmutated IgVH regions (Ig-unmutated CLL) often have progressive disease whereas patients whose leukemic cells express mutated IgVH regions (Ig-mutated CLL) more often have an indolent disease. Given the difficulty in performing IgVH sequencing in a routine diagnostic laboratory, this prognostic distinction is currently unavailable to most patients. Pilot gene expression profiling studies in CLL patients identified genes that were differentially expressed between the Ig-unmutated and Ig-mutated CLL subtypes. Here, we have profiled an expanded cohort of 107 patients, and show that ZAP-70 is the gene that best distinguishes the CLL subtypes. Ig-unmutated CLL expressed ZAP-70 5.54-fold more highly than Ig-mutated CLL (p<10-21). ZAP-70 expression correctly predicted IgVH mutation status in 93% of patients. ZAP-70 expression and IgVH mutation status were comparable in their ability to predict time to treatment requirement following diagnosis. In 7 patients, ZAP-70 expression and IgVH mutation status were discordant: 4 Ig-mutated CLLs had high ZAP-70 expression and 3 Ig-unmutated CLLs had low ZAP-70 expression. Among these ZAP-70 “outliers”, those with Ig-mutated CLL had clinical features that are uncharacteristic of this CLL subtype: 2 required early treatment and 2 used a mutated VH3-21 gene, an IgVH gene that has been associated with progressive disease. We developed RT-PCR and immunohistochemical assays for ZAP-70 expression that can be applied clinically and would yield important prognostic information for CLL patients.
Understanding Prognostic Indicators
by Chaya Venkat
A member raised the following excellent questions. One of my old professors used to tell me that the real test of understanding is being able to ask good questions. This lady certainly goes to the top of the class.
I segregated four different questions from her message, and I will try to answer them accordingly. Lots of ifs and buts, I am afraid.
1. Since CD20 is expressed only by mature B-cells, not by any of the other cell lines, and all mature B-cells are also CD19 positive, it is not necessary to define CD20 positivity as CD19/CD20 positivity. 100% CD19 positivity can be taken for granted on the mature B-cells.
2. CD38 is normally exhibited by T-cells, activated T-cells and plasma cells. It is not a marker that is routinely exhibited by healthy B-cells. So, once we have defined a population of B-cells by virtue of their being CD19/CD5 positive, then we further see how many of these CD19/CD5 positive cells are also CD38 positive, we are indeed looking for the abnormal B-cells. In a healthy person with no CLL, I expect the percentage of B-cells that are CD19/CD5/CD38 positive, i.e., have all three CD markers, would be close to zero.
So. If we look for cells that have just CD38 (single gating), that number would include T-cells as well, for example. If we look for cells that are CD19/CD38 positive (double gating), that would look at B-cells (CD19 positive) that are also CD38 positive. Finally, if we look for CD19/CD5/CD38 positive (triple gating), we are looking for a subset of B-cells that are classified as CLL cells (CD19/CD5 positivity is the classic definition of CLL cells) that are also likely to be "bad" CLL cells, because they have the CD38 marker as well.
You can see that the % number depends on whether you do single gating, double gating or triple gating. A question of apples and oranges indeed, if one tries to apply research findings using one set across all three sets.
3. Your CD38 levels on CLL cells may have gone up, or there may be a question of different gatings used in obtaining the numbers the two times. Hard to tell, without more information, or even then.
4. Yes, there is some concern that CD38 positivity on CLL cells can change over time, for a portion of the patient population. No one knows why this happens. And yes, it does decrease the prognostic value of this test. I think I wrote a while ago, there is a clonal evolution of CLL cells over time. Some patients who had no mutation in their p53 gene (good sign) over time are seen to have acquired the p53 mutation. Same is true for other chromosomal abnormalities.
I had written this is one reason to consider earlier intervention, especially if non-toxic therapies are possible. W&W may have been the choice, when there were no good, non-toxic therapies available. But if that has now changed with potential immunotherapy options, are patients taking an unnecessary risk of their CLL clonal population evolving to a more malignant and refractory form? Might it not be better to nip it in the bud to the level possible, earlier in its life? There is preliminary indication that with increasing numbers of CLL cells, there is a higher likelihood of picking up new chromosomal aberrations in addition to the ones you got in the first place. I think the same logic applies to CD38 positivity as well. I will wrap this up with one further thought: we are all aware that Beta-2-microglobulin (B2M) is considered a prognostic indicator. But all you have to do is look at a number of patients' charts to see this indicator "evolves" to very high numbers as the disease progresses, and then drops back after therapy, when the CLL is under control. The same is true of CD23, the B-cell activation marker, also considered to be a valuable prognostic indicator. In my husband's case, it sky rocketed from the low value it used to be, after he had what we consider a viral infection (unfortunately, its identity was never confirmed by all the tests that were performed), along with rapidly increasing lymphocyte counts.
As you can tell, we are still in the early stages of getting a good fix on this disease. And when we learn a lot more about these prognostic indicators, I am pretty sure we will find that they are not static indicators that stay unchanged, they change as the CLL changes. One of the researchers at my husband's CLL Consortium Center had this to say about my his very favorable flow cytometry results, right after he was diagnosed: "Nice snapshot! Now we need to see the video, to see how it plays out over a period of time". How true.
Prognostic Indicators and Therapy Choices
by Chaya Venkat
There has been a lot of interest and a re-visiting of the value of IgVH gene mutation status as a prognostic indicator in CLL on this site as well as others. From my review of this subject, there seems to be little doubt it does provide very important prognostic value. Patients with mutated IgVH gene have, statistically speaking, longer survival rates than patients who have the unmutated version. Please see the recent article on this page on what exactly is meant by "IgVH gene mutation". This is not, repeat not the same as chromosomal aberrations that are sometimes present in CLL patients.
It is unfortunate that it is difficult and expensive to routinely monitor this particular prognostic indicator, because it may have value in determining optimal therapy choices for patients. After all, if you have reasonable assurance that you are going to be one of the lucky ones with a slow and smoldering variety of CLL, it does not make sense to sign up immediately for heavy duty therapy that may have other and unwanted consequences. On the other hand, people who are likely to have a more aggressive form of the disease may wish to reconsider the watch and wait paradigm, it might not be the best solution for them, and they might be better off initiating therapy before the onset of B-symptoms. Preemptive action may not be necessary for the former group, and of great value for the latter group.
I can personally attest to the difficulty of getting this IgVH gene testing done for the majority of patients. Most insurance companies do not cover it, and most labs are not equipped to do it. A few of us may be lucky to be in clinical trials where this done as part of the trial, or be able to afford going overseas to get it done out of pocket. It is going to be a while before patients can access this potentially valuable prognostic information as a routine blood test, after they are diagnosed with CLL. The pity of it is that the upfront "cost" of doing tests like this may actually save more money down the road for our healthcare industry, in terms of being able to defer therapy for people who may not need it for a long time!
In this country we are some what "spoiled", in terms of expecting and demanding the latest and best technology for all our patients. Public policy regarding healthcare for all of our citizens has this schizoid split: on the one hand, we want our patients to have the best available healthcare, no amount of money or heroic effort is too much to extend the duration and/or quality of life for cancer patients. On the other hand, we have a significant portion of our citizens with no healthcare insurance at all, not even the bare minimum and extremely cost effective preventive care, not even for many of our children. I hear sometimes from patients in third world countries such as India, where the "cutting edge" drug recently to treat CLL is Fludarabine. Rich people in India get access to Fludarabine. Poorer patients have to make do with Chlorambucil, if they get anything at all. As for monoclonals like Rituxan, that is not even in the realm of reality for the vast majority of the world, even in many relatively affluent countries.
Discussing public policy with regard to healthcare is an explosive issue, and decisions are not always made on the basis of fairness or maximizing benefits for the largest portion of our citizens. Since CLL Topics is not a political site, I will now get off the soap box, with apologies to all of you for breaking my own rules on excluding politically sensitive comments.
So, given that reality is something to deal with, and not much point bitching about, there is a great deal of interest in finding a test or maker that mimics the IgVH gene mutation status, that can be done more readily and cheaply by commercial labs. Please see my previous articles on this page on the percentage of CLL cells that exhibit the CD38 marker as a possible prognostic tool. Damle et al have published extensively on this subject. The jury is still out on the exact correlation between CD38 negativity and IgVH gene mutation. Both seem to be independent markers for good prognosis, but it is not clear if the two indicators march in lock step. There is also some discussion on exactly what level of CD38 negativity constitutes a good prognosis, the original article by Damle looks at 30% as the cut off for CD38 positivity on cells that are also CD5 and CD19 positive (CLL cells have characteristic display of both CD5 and CD19). More recent papers have suggested lower cut offs, in the range of 20% or lower, of cells exhibiting CD5/CD19/CD38. Even this test requires triple gating of the flow cytometry, looking for cells that exhibit all three CD markers. M. D. Anderson's testing looks for CD19/CD38 positive cells, for example, not the more finely defined triple positive CD5/CD19/CD38 cells. The correlations between the double positive and triple positive populations have not been clearly defined, yet.
Below is a PubMed citation that suggests ZAP-70 expression as a surrogate for IgVH gene mutation status. Patients with un-mutated IgVH gene also express the ZAP-70 gene roughly five times more than the lucky patients with IgVH mutated gene. Even this is not a simple diagnostic test, it requires real time polymerase chain reaction tests (RT-PCR), or careful immunohistochemical assays. But the claim is that it is more likely to become an accessible test, compared to testing for IgVH gene mutation status.
Blood 2003 Feb 20; [epub ahead of print]
ZAP-70 expression identifies a chronic lymphocytic leukemia subtype with unmutated immunoglobulin genes, inferior clinical outcome, and distinct gene expression profile.
Wiestner A, Rosenwald A, Barry TS, Wright G, Davis RE, Henrickson SE, Zhao H, Ibbotson RE, Orchard JA, Davis Z, Stetler-Stevenson M, Raffeld M, Arthur DC, Marti GE, Wilson WH, Hamblin TJ, Oscier DG, Staudt LM.
Metabolism Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD.
The presence or absence of somatic mutations in the expressed immunoglobulin heavy chain variable regions (IgVH) of chronic lymphocytic leukemia (CLL) cells provides prognostic information. Patients whose leukemic cells express unmutated IgVH regions (Ig- unmutated CLL) often have progressive disease whereas patients whose leukemic cells express mutated IgVH regions (Ig-mutated CLL) more often have an indolent disease. Given the difficulty in performing IgVH sequencing in a routine diagnostic laboratory, this prognostic distinction is currently unavailable to most patients. Pilot gene expression profiling studies in CLL patients identified genes that were differentially expressed between the Ig-unmutated and Ig-mutated CLL subtypes. Here, we have profiled an expanded cohort of 107 patients, and show that ZAP-70 is the gene that best distinguishes the CLL subtypes. Ig-unmutated CLL expressed ZAP-70 5.54-fold more highly than Ig-mutated CLL (p<10(-21)). ZAP-70 expression correctly predicted IgVH mutation status in 93% of patients. ZAP-70 expression and IgVH mutation status were comparable in their ability to predict time to treatment requirement following diagnosis. In 7 patients, ZAP- 70 expression and IgVH mutation status were discordant: 4 Ig-mutated CLLs had high ZAP-70 expression and 3 Ig-unmutated CLLs had low ZAP- 70 expression. Among these ZAP-70 "outliers", those with Ig-mutated CLL had clinical features that are uncharacteristic of this CLL subtype: 2 required early treatment and 2 used a mutated VH3-21 gene, an IgVH gene that has been associated with progressive disease. We developed RT-PCR and immunohistochemical assays for ZAP-70 expression that can be applied clinically and would yield important prognostic information for CLL patients.
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