Understanding Serum Free Light Chain Assays

Transcription

Multiple Myeloma | Cancer of the Bone Marrow
Understanding
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© 2016, International Myeloma Foundation, North Hollywood, California – u-fl-hl_2016_EN_k3
Freelite® and
Hevylite® Tests
A publication of the International Myeloma Foundation
Improving Lives Finding the Cure®
Table of contents
About the International Myeloma Foundation
Founded in 1990, the International Myeloma Foundation (IMF) is the
oldest and largest myeloma-specific charity in the world. With more than
350,000 members in 140 countries, the IMF serves myeloma patients, family
members, and the medical community. The IMF provides a wide range of
programs in the areas of Research, Education, Support, and Advocacy:
RESEARCH The IMF is the leader in globally collaborative myeloma research.
The IMF supports lab-based research and has awarded over 100 grants to top
junior and senior researchers since 1995. In addition, the IMF brings together
the world’s leading experts in the most successful and unique way through
the International Myeloma Working Group (IMWG), which is publishing in
prestigious medical journals, charting the course to a cure, mentoring the next
generation of innovative investigators, and improving lives through better care.
The Understanding series and 10 Steps to Better Care
4
What you will learn from this booklet
4
Multiple myeloma and monoclonal protein
4
What are free light chains?
5
The role of the Freelite assay
5
Normal vs. abnormal light chain levels
7
The kappa/lambda ratio
7
How can the Freelite assay help detect and monitor myeloma?
8
Freelite levels and the assessment of response to treatment,
including stringent complete response
10
Center Workshops, and Regional Community Workshops are held around the
world. These meetings provide up-to-date information presented by leading
myeloma specialists and researchers directly to myeloma patients and their
families. Our library of more than 100 publications, for patients and caregivers
as well as for healthcare professionals, is updated annually and available free
of charge. Publications are available in more than 20 languages.
Patients who benefit the most from the Freelite assay
11
What is the Hevylite assay?
15
What is a heavy/light chain ratio?
16
SUPPORT Our toll-free InfoLine at 800-452-CURE (2873) is staffed by
coordinators who answer questions and provide support and information
via phone and email to thousands of families each year. The IMF sustains a
network of more than 150 support groups and offers training for the hundreds
of dedicated patients, caregivers, and nurses who volunteer to lead these
groups in their communities.
How does the Hevylite assay differ from SPEP?
16
The Hevylite assay and monitoring for relapse
16
The Hevylite assay and monitoring for residual disease
17
ADVOCACY The IMF Advocacy program trains and supports concerned
What are normal Hevylite levels?
17
Can Freelite and Hevylite be used together?
17
Will insurance cover the cost of Freelite and Hevylite assays?
17
In closing
17
Terms and definitions
18
EDUCATION The IMF’s educational Patient & Family Seminars, Medical
individuals to advocate on health issues that affect the myeloma community.
Working both at the state and federal level, the IMF leads two coalitions to
advocate for parity in insurance coverage. Thousands of IMF-trained advocates
make a positive impact each year on issues critical to the myeloma community.
Learn more about the way the IMF is helping to improve the quality of life
of myeloma patients while working toward prevention and a cure.
Contact us at 800-452- CURE (2873) or 818-487-7455,
or visit myeloma.org.
The Understanding series
and 10 Steps to Better Care
What you will learn
from this booklet
The IMF’s Understanding series of booklets
is designed to acquaint you with treatments and supportive care measures for
multiple myeloma (which will be referred
to as myeloma for the sake of brevity).
As more drugs become available to treat
myeloma, it is vital to learn as much as
possible about each new type of therapy.
The Understanding Freelite® and Hevylite®
Tests booklet is devoted to two tests
used in the diagnosis and monitoring of
myeloma, the serum free light chain assay
(Freelite®) and the serum heavy/light
chain assay (Hevylite®). This Understanding booklet presents information on tests
used to diagnose and monitor myeloma,
and to detect relapse. It fits into the 10
Steps to Better Care schema in:
For a general overview of myeloma, the
IMF’s Patient Handbook should be your
first step, while the IMF’s Concise Review
of the Disease and Treatment Options is a
more in-depth summary for healthcare
professionals and knowledgeable readers outside the medical community. Both
publications, as well as the many booklets
in the IMF’s Understanding series, are available on the IMF website, myeloma.org,
where you will find a wealth of information. You can also order copies of IMF
booklets by calling 800-452-CURE (2873)
toll-free in the United States and Canada,
or 818-487-7455 worldwide, or by emailing
[email protected].
To help you navigate the IMF website, we
have organized our information according to the 10 Steps to Better Care®, which
takes you from diagnosis (Step 1) through
clinical trials and how to find them
(Step 10). Information relevant to each
step along the way, including guidelines
for testing, treating, transplanting, assessing response, managing side effects,
monitoring, and treating relapsed disease, is available under the appropriate
step on the path to better care.
Words in bold type are explained in the
“Terms and definitions” section at the end
of this booklet. A more complete compendium of myeloma-related vocabulary, the
IMF’s Glossary of Myeloma Terms and Definitions, is located at glossary.myeloma.org.
4
Step 1 – Get the correct diagnosis
Step 2 – Tests you really need
Step 6 – Response assessment
Step 8 – Monitoring without mystery
Step 9 – Relapse: Do you need a
change in treatment?
An important note: The total light chain
assay, an older test used to quantify
bound and free light chains, is not useful
for myeloma patients. The Freelite assay
must be specified by your doctor in order
to benefit from the newest and best technology available.
M-protein. Other names for M-protein
are myeloma protein, paraprotein, or the
M-spike. The identification of an M-protein
is important for diagnosis, and the measurement of its level is an aid both for
monitoring the effectiveness of treatment
and for identifying a relapse.
What are free light chains?
Structurally, normal immunoglobulins
(abbreviated “Ig”) are composed of
smaller units called heavy chains and light
chains, and together they form a large
complex (see Figure 1). There are five types
(also called isotypes) of heavy chains, and
each type is assigned a specific letter.
These five types are abbreviated as IgG,
IgA, IgD, IgE, and IgM.
There are two types of light chains, and
they are referred to as kappa or κ and
lambda or λ. Each plasma cell produces
only one type of heavy chain and one
type of light chain. Altogether, there are
10 subtypes of normal immunoglobulins
(see Table 1).
Figure 1. Structure of an
immunoglobulin (antibody)
Multiple myeloma and
monoclonal protein
In myeloma, a cancer of the plasma
cells in the bone marrow, one particular
plasma cell (a clone) is duplicated a very
large number of times, causing excess
production of one type of immunoglobulin. This single type of immunoglobulin is called a monoclonal protein or
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Table 1. Subtypes of Immunoglobulins
IgG Kappa
IgG Lambda
IgA Kappa
IgA Lambda
IgM Kappa
IgM Lambda
IgD Kappa
IgD Lambda
IgE Kappa
IgE Lambda
The heavy and light chains are produced
separately within the plasma cells and
are assembled to form a whole (“intact”)
immunoglobulin. When the light chains
are attached to the heavy chains, the
light chains are referred to as “bound light
chains.” 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 whole immunoglobulins or monoclonal proteins. The
excess light chains enter the bloodstream
as free light chains (that is, not attached
to the heavy chains). Thus, both in healthy
individuals and in individuals with
myeloma and related disorders, such as
monoclonal gammopathy of undetermined significance (MGUS), excess light
chains enter the bloodstream as free light
chains. For myeloma patients, the amount
of free light chain production is linked to
the activity of myeloma cell growth: the
more myeloma cells, the greater the production of monoclonal protein.
The role of the Freelite assay
How is monoclonal protein
detected and measured?
Monoclonal proteins may be detected
and measured in blood and/or urine.
myeloma.org
5
When measurements are taken in blood,
all of the cells are removed from the blood
sample, leaving only the yellow liquid
component of the blood that is called
“serum.” Several tests can be ordered to
detect the M-protein, including serum
protein electrophoresis (SPEP), urine
protein electrophoresis (UPEP), and the
serum free light chain assay (SFLCA, or
Freelite). If only one type of light chain
(kappa OR lambda and not both kappa
AND lambda) is produced in excess, this
means that myeloma cells are secreting
monoclonal protein. SPEP measures the
amount of monoclonal protein in the
blood and UPEP measures the amount
of monoclonal light chain in the urine,
but neither test can identify the type
of monoclonal protein. That is done by
immunofixation electrophoresis (IFE),
which, in turn, only determines if a particular type of monoclonal protein is present, but does not quantify the amount.
Patients with elevated levels of free light
chains have traditionally been diagnosed and monitored using UPEP; this
test has been required in all clinical trials
for myeloma. However, a paper from the
French myeloma study group recently
6
published in the journal Haematologica
compared serum Freelite and 24-hour
urine UPEP results after 2 and 4 cycles of
therapy and after stem cell transplantation in patients enrolled in the IFM2007-02
study. The authors “found good agreement between methods for response
assessment [after 2 cycles of therapy] but
the serum free light chain test provided
greater sensitivity than urine electrophoresis for monitoring.” Because light
chains are first released into the blood
and then filtered by the kidneys before
they reach the urine, UPEP is not a highly
sensitive test. However, the Freelite assay
is a blood test and it quantifies the level of
light chains in the blood before the light
chains are filtered by the kidneys. Moreover, patient compliance with 24-hour
urine collection is poor, not surprisingly,
making response assessment difficult and
compromising the results of clinical trials.
As a result of the Haematologica publication, the IMWG is expected to change its
guidelines for serum free light chain analysis and to accept the Freelite test in lieu
of 24-hour urine collection and urine protein electrophoresis. We anticipate that
these new guidelines will be published in
early 2016.
The Freelite assay
The Freelite assay is capable of detecting
free light chains at their normal (non-elevated) levels in the blood. Freelite can
detect light chains at levels lower than normal concentration (i.e., to detect suppression). Importantly, this assay can detect
mildly increased levels of free light chains
even when these levels are undetectable
by SPEP and IFE. This means that multiple
myeloma could be detected earlier than
might be possible with either SPEP or IFE.
Moreover, the Freelite assay is particularly useful in instances when only small
amounts of light chains are produced by
the myeloma.
Freelite is best performed on serum
rather than urine because of the filtering
effects of the kidneys. Part of the normal
function of the kidneys is to prevent protein loss from the body into the urine. As
a result, an elevated level of M-protein
may be detected in the blood before it
is detected in the urine. Urine studies
are still important, however, in the initial
diagnosis and subsequent monitoring of
AL amyloidosis. Urine studies show other
aspects of myeloma disease, like kidney
damage, and should be included in the
work-up of myeloma.
Like other tests that detect M-protein, the
Freelite assay has advantages and disadvantages. As discussed above, one advantage is greater sensitivity than is available
with SPEP, UPEP, and IFE. Another advantage is that the Freelite assay is automated and therefore requires less time
to perform in the laboratory than SPEP,
UPEP, and IFE. However, although the
Freelite assay is excellent for detection
of free light chains, it is unable to detect
whole immunoglobulins. Some types
of myeloma secrete only whole immunoglobulins. Recently, a new laboratory
test called Hevylite became available to
measure intact immunoglobulin heavy/
light chain pairs. Like Freelite, Hevylite
can be measured in normal serum and is
more sensitive than SPEP. More information about Hevylite can be found later in
this booklet.
myeloma.org
Normal vs. abnormal
light chain levels
Normal levels of serum free light chains
are*:
nK
appa: 3.3–19.4 mg/L or
0.33–1.94 mg/dL
n
n
L ambda: 5
.71–26.3 mg/L or
0.57–2.63 mg/dL
K
appa/lambda ratio: 0.26–1.65*
*Note: In patients with renal impairment,
it is recommended to interpret the
results of the kappa/lambda ratio with
a modified reference range of 0.37–3.1.
In the majority of cases, light chains produced by myeloma cells will be exclusively
kappa or lambda, depending upon the
type of myeloma. Thus, if the myeloma
cells produce kappa light chains, the level
of kappa free light chains will increase
in the blood. If, on the other hand, the
myeloma cells produce lambda light
chains, the level of lambda free light
chains will increase in the blood. Your
doctor will need to interpret the results
of the Freelite assay together with other
clinical information in order to make a
final interpretation of the results.
The kappa/lambda ratio
nT
he Freelite kappa/lambda ratio is as
important for diagnosis and monitoring of myeloma as are the levels of
kappa and lambda light chains.
n
n
W
hen the level of either kappa or
lambda is very high and the other light
chain is normal or low, then the ratio
is abnormal and indicates that the
myeloma is present.
If levels of both kappa and lambda light
chains are increased, the ratio may be
7
within the normal range, but this generally indicates a disease other than
myeloma, such as poor kidney function. When the kidneys are not working
properly, both types of light chains
are retained in the blood and are not
removed by the kidneys.
n
n
S ometimes the kappa/lambda ratio
may be abnormal even though the
individual kappa and lambda levels
are both within the normal range. This
can be indicative of a persistent low
level of active myeloma.
A
normal kappa/lambda ratio after
treatment signifies a particularly effective response. It is part of the definition
of a “stringent complete response”
(sCR), which also requires negative
urine/serum IFE and absence of clonal
cells in the bone marrow. Normalization of the kappa/lambda ratio correlates with possible longer remissions.
How can the Freelite
assay help detect and
monitor myeloma?
Changes in free light chain levels are useful for tracking the disease status in almost
all people with myeloma, not just those
with light chain (Bence-Jones) myeloma
or nonsecretory disease. The Freelite test
can help in the detection and monitoring
of myeloma by quantifying monoclonal
protein in multiple disease settings.
Intact immunoglobulin
multiple myeloma (IIMM)
IIMM accounts for more than 80% of
myeloma cases. In IIMM, the cancerous
plasma cells produce one type of intact
immunoglobulin, and in the majority of
these cases, either kappa or lambda free
light chains are also produced. Because
free light chains are filtered by the kidneys
rather quickly (within just a few hours),
changes in blood levels in response to
treatment occur rapidly. Decreases in
free light chain levels can therefore be a
very sensitive indicator of early response
in IIMM.
Light chain multiple myeloma (LCMM)
LCMM comprises 15%–20% of all myelomas. In LCMM the myeloma plasma cells
produce only light chains. Freelite has
100% proven sensitivity in detection of
light chains in these patients. It is a better indicator of minimal residual disease
and disease changes than urine measurement, which can be influenced by renal
function. The Freelite assay is also more
sensitive for monitoring LCMM patients
who may not secrete enough protein
to be detected by other serum tests or
urine tests.
8
Nonsecretory and
oligosecretory myeloma
Some myeloma plasma cells produce very
little or no M-protein. In the case where
there is no M-protein, the result is referred
to as nonsecretory myeloma. When the
myeloma plasma cells secrete a very low
level of M-protein, the disease is called
oligosecretory myeloma. These types of
myeloma comprise a very small percentage of all the myelomas. Approximately
70% to 80% of people with M-protein
that is too low to detect by other methods have measurable M-protein using the
Freelite assay.
Freelite at relapse
At the time of relapse, the sensitivity of
the free light chain assays is also very
important. Even very small amounts of
myeloma that start to grow as part of
relapse produce measurable amounts of
free light chains in most instances. The
serum free light chain levels of either
kappa or lambda, depending upon the
type of myeloma, may increase before
the increases in IgG and IgA and other
immunoglobulins can be detected by
SPEP or IFE. Other tests such as bone
marrow biopsy, and imaging tests such
as FDG-PET or PET-CT, are also useful
in the assessment of minimal amounts
of disease.
Light chain escape (LCE)
At the time of relapse, the pattern of
myeloma immunoglobulin production
can change. For example, plasma cells
that produced both intact immunoglobulins and free light chains may change so
that only free light chains are produced,
myeloma.org
or a clone of plasma cells that produced
intact immunoglobulin may have been
eradicated by therapy, while a small subclone that produced only free light chains
may have survived and expanded. These
situations result in what is called light
chain escape (LCE). The most sensitive
way LCE can be detected earlier in relapse
is by measurement of the blood with the
Freelite assay.
Monoclonal gammopathy of
undetermined significance (MGUS)
Patients who have been diagnosed with
MGUS have some blood characteristics of
myeloma but do not have active disease,
and they do not need to be treated. For
example, they may have elevated levels of
immunoglobulins and/or free light chains
and/or plasma cells. Patients with MGUS
can be risk-stratified to assess their chance
of developing active disease. A study from
the Mayo Clinic showed that patients with
MGUS who also have an abnormal free
light chain ratio are more likely to progress
and develop active myeloma or a related
malignant condition.
Smoldering multiple myeloma (SMM)
or asymptomatic multiple myeloma
Patients with SMM have higher levels of
immunoglobulins and/or free light chains
and/or plasma cells in the blood than
patients with MGUS. They still do not have
active disease and have not sustained
damage to their bones, kidneys, or red
blood cells. However, the chance that they
will develop active disease is much greater
than patients with MGUS. SMM patients
should be monitored at regular intervals and should discuss how often they
need to be tested for active disease with
9
Enrollment in clinical trials
their doctors. A small percentage of SMM
patients have a high risk of progressing
to active myeloma. These patients, who
have a free light chain ratio ≥ 100 or ≤ 0.01,
≥ 60% bone marrow plasma cells, or more
than one focal lesion detected by MRI, are
now defined as having active myeloma by
the International Myeloma Working Group
(IMWG) because they have a greater than
80% risk of progressing to active myeloma
within two years (Rajkumar et al., The Lancet, vol. 15 no. 12, November 2014). Clinical
trials have been initiated to determine if
there is any benefit in treating patients
with “high-risk” SMM before they have
symptoms of active disease.
AL amyloidosis
Amyloid light chain (AL) amyloidosis is a
disease that occurs when the light chains
are misformed in a characteristic “beta
pleating” pattern that results in deposition of rigid fibrils in such places as the
kidneys, heart, liver, tongue, and peripheral nerves. Measurement of serum free
light chains has been recommended
for the diagnosis and monitoring of
AL amyloidosis since 2004.
10
Clinical trials are the only route by which
new medicines are made available and
a potential cure discovered. People with
myeloma may participate in clinical trials
to help test the safety and effectiveness of
new treatments. In order for a patient with
myeloma to be eligible to participate in a
trial, there must be a way to monitor their
M-protein levels in the blood or urine.
People with hyposecretory disease used
to be excluded from clinical trials because
there was no method to monitor their
M-protein levels. With the availability of
the Freelite assay, the M-protein level can
be monitored in the blood of the majority
of these people. Therefore, people with
low-secreting disease are often eligible to
participate in clinical trials.
Freelite levels and the
assessment of response
to treatment, including
stringent complete response
One of the goals of myeloma treatment is
to reduce the level of M-protein as much
as possible, and sometimes to eliminate
it entirely. Serum free light chain levels,
as measured by the Freelite assay, can be
used in the same way as monoclonal protein measurements to assess response to
treatment, but they can also be used more
frequently in the early weeks of treatment.
With the advent of newer and more sensitive laboratory techniques, very small
amounts of myeloma disease can be
measured by flow cytometry or genome
sequencing analysis of bone marrow
biopsy samples. This small amount
of myeloma disease is called Minimal
Residual Disease, or MRD, and testing for
MRD should be potentially performed
only after other laboratory tests for the
M-protein (i.e., SPEP, Freelite, Hevylite)
show no detectable disease. Table 2
details the criteria for assessing patient
response to treatment, including stringent complete response and measuring
minimal residual disease. If the free light
chain ratio becomes normal after treatment, then this provides a very good and
sensitive indication that treatment has
been highly effective, and means that the
level of light chain paraprotein has been
reduced as much as possible.
Normalization of the Freelite ratio is
a component of a stringent complete
response (sCR). Updated IMWG consensus
guidelines on the assessment of minimal
residual disease (MRD) defi e sCR as:
n
n
n
n
n
n
egative IFE on the serum and urine,
d
isappearance of any soft tissue
plasmacytomas,
<
5% plasma cells in bone marrow
aspirates,
a bsence of clonal cells in bone marrow
by immunohistochemistry (κ/λ ratio
≤ 4:1 or ≥ 1:2 for k and λ patients, respectively, after counting ≥ 100 plasma
cells) or 2- to 4-color flow cytometry in
bone marrow aspirates, and
n
n
n
n
T he Freelite assay, along with other
tests, can provide valuable information for people with MGUS and SMM.
U
se of the Freelite assay to monitor
treatment reveals responses to treatment earlier than other laboratory
tests such as SPEP.
T he improved sensitivity of the Freelite
assay over IFE may allow earlier detection of a relapse of myeloma.
T he Freelite assay is recommended for
use in diagnosis, prognosis, and monitoring in the guidelines published by
the IMWG.
Current National Comprehensive Cancer
Network (NCCN) Clinical Practice Guidelines in Oncology recommend the use of
polyclonal serum free light chain assays
(Freelite) for diagnosis, prognosis, and
monitoring of myeloma.
Patients who benefit the
most from the Freelite assay
nP
eople with myeloma who have
abnormal serum free light chain
results at the start of treatment. Monitoring with the serum free light chain
n
ormal free light chain ratio.
In summary, the Freelite assay offers several advantages for diagnosis and monitoring of treatment:
n
Inclusion of Freelite assay can improve
the sensitivity of screening protocols for
detection and diagnosis of myeloma.
myeloma.org
11
Table 2. IMWG Criteria for Patient Response to Treatment
Response
subcategory
Response
subcategory
Response criteria1
IMWG MRD negativity criteria (Requires CR as defined below)
Standard IMWG Response criteria6
Sustained
MRD-negative
MRD negative in the marrow (Next-Generation flow or Next-Generation Sequencing) and by
imaging as defin d below, confi med one year apart.2 Subsequent evaluations can be used to
further specify the duration of negativity (e.g., MRD negative @ 5 years etc)
Flow
MRD-negative
Absence of phenotypically aberrant clonal plasma cells by Next-Generation Flow cytometry4
on bone marrow aspirates using the EuroFlow standard operation procedure for MRD detection
in MM (or validated equivalent method) with a minimum sensitivity of 1 in 105 nucleated cells
or higher
Sequencing
MRD-negative
Absence of clonal plasma cells by Next Generation Sequencing on bone marrow aspirates in
which presence of a clone is defined as less than 2 identical sequencing reads obtained after
DNA sequencing of bone marrow aspirates using the Lymphosight® platform (or validated
equivalent method) with a minimum sensitivity of 1 in 105 nucleated cells5 or higher
Imaging
MRD-negative
• MRD negative as defin d by Next-Generation Flow or Next-Generation Sequencing PLUS
• Disappearance of every area of increased tracer uptake found at baseline or a preceding PET/CT3
SD
(stable disease)
(Not recommended for use as an indicator of response; stability of disease is best described by
providing the time to progression estimates)
Not meeting criteria for CR, VGPR, PR, MR, or progressive disease (PD)
PD
(progressive
disease)8,9
Any one or more of the following:
• Increase of 25% from lowest response value in one or more of below:
• Serum M-protein (absolute increase must be ≥ 0.5 g/dl)
• Serum M-protein increase ≥ 1 g/dl, if lowest M-protein was ≥ 5 g/dl
• Urine M-protein (absolute increase must be ≥ 200 mg/24 h)
• In patients without measurable serum and urine M-protein levels, the difference between
involved and uninvolved FLC levels (absolute increase must be > 10 mg/dl)
• In patients without measurable serum and urine M-protein levels and without measurable
involved FLC levels, bone marrow plasma cell percentage irrespective of baseline status
(absolute % increase must be ≥ 10%)
• Appearance of a new lesion(s), ≥ 50% increase from nadir in SPD (sum of perpendicular
diameters) of more than one lesion, or ≥ 50% increase in the longest diameter of a previous
lesion > 1 cm in short axis.
• ≥ 50% increase in circulating plasma cells (minimum of 200/mcl)
Clinical Relapse
Clinical relapse requires one or more of:
Direct indicators of increasing disease and/or end organ dysfunction (CRAB features) felt
related to the underlying clonal plasma cell proliferative disorder. It is not used in calculation
of time to progression or progression-free survival but is listed as something that can be
reported optionally or for use in clinical practice
• Development of new soft tissue plasmacytomas or bone lesions
• Definite increase in the size of existing plasmacytomas or bone lesions. A definite increase is
defined as a 50% (and at least 1 cm) increase as measured serially by the sum of the products
of the cross-diameters of the measurable lesion
• Hypercalcemia (≥ 11.5 mg/dl)
• Decrease in hemoglobin of ≥ 2 g/dl not related to therapy
• Rise in serum creatinine by 2 mg/dl or more
• Hyperviscosity related to serum paraprotein
Relapse from CR
(To be used only
if the end point
is disease-free
survival [DFS])
• Reappearance of serum or urine M-protein by immunofixation or electrophoresis
• Development of ≥ 5% plasma cells in the bone marrow
• Appearance of any other sign of progression (i.e., new plasmacytoma, lytic bone lesion, or
hypercalcemia see below)
Relapse from
MRD negative
(To be used only
if the end point
is DFS)
• Loss of MRD-negative state (evidence of clonal plasma cells on Next-Generation flow or
sequencing, or positive imaging study for recurrence of myeloma
• Reappearance of serum or urine M-protein by immunofixation or electrophoresis
• Development of ≥ 5% plasma cells in the bone marrow
• Appearance of any other sign of progression (i.e., new plasmacytoma, lytic bone lesion,
or hypercalcemia)
Standard IMWG Response criteria6
sCR
(stringent
complete
response)
• CR as defined below PLUS
• Normal FLC ratio10 AND
• Absence of clonal cells in bone marrow biopsies by immunohistochemistry (κ/λ ratio ≤ 4:1
or ≥ 1:2 for κ and λ patients, respectively, after counting ≥ 100 PCs)7 or 2- to 4- color flow
cytometry in bone marrow aspirates
CR
(complete
response)
• Negative immunofixation on the serum and urine AND
• Disappearance of any soft tissue plasmacytomas AND
• < 5% plasma cells in bone marrow aspirates (If cellular MRD is to be performed, the first BM
aspirate should be sent to MRD and morphological evaluation is not mandatory)
• Serum and urine M-protein detectable by immunofixation but not on electrophoresis OR
VGPR
(very good
•≥
90% reduction in serum M-protein PLUS
partial response) • urine M-protein level < 100mg per 24 hours
PR
(partial
response)
MR
(minimal
response)
• ≥ 50% reduction of serum M-protein and reduction in 24-h urinary M-protein by ≥ 90%
or to < 200 mg per 24 hours.
• If the serum and urine M-protein are unmeasurable, a ≥50% decrease in the difference
between involved and uninvolved FLC levels is required in place of the M-protein criteria
• If serum and urine M-protein are unmeasurable, and serum free light chain assay is also
unmeasurable, ≥ 50% reduction in plasma cells is required in place of M-protein, provided
baseline bone marrow plasma cell percentage was ≥ 30%
• In addition to the above listed criteria, if present at baseline, a ≥ 50% reduction in the size of
soft tissue plasmacytomas is also required
• ≥ 25% but ≤ 49% reduction of serum M-protein and reduction in 24-hour urine M-protein
by 50%–89%
• In addition to the above listed criteria, if present at baseline, a ≥ 50% reduction in the size of
soft tissue plasmacytomas is also required
(Table 2 continues on next page)
12
Response criteria1
Abbreviations: MRD, minimal residual disease; CR, complete response; FLC, free light chain; PR, partial response;
SD, stable disease; sCR, stringent complete response; VGPR, very good partial response.
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13
Footnotes to Table 2.
1.All response categories require two consecutive assessments made at any time before the institution of any new
therapy; for MRD there is no need for two consecutive assessments, but information on MRD after each treatment
stage is recommended (e.g.: after induction, HDT/ASCT, consolidation, maintenance). MRD tests should be initiated
only at the time of suspected CR. Early indications from studies suggest that bone marrow aspirates for MRD testing
by fl w should only be done if there is normalization of Freelite and Hevylite assays. Bone marrow should only be
sampled two months after CR is reached in order to ensure that the bone marrow has had time to refle t the negative status. All categories of response and MRD also require no known evidence of progressive or new bone lesions
if radiographic studies were performed. However, radiographic studies are not required to satisfy these response
requirements except for the requirement of FDG-PET if imaging MRD-negative status is reported.
2.Sustained MRD-negative when reported should also annotate the method used (e.g., Sustained Flow MRD-negative,
Sustained Sequencing MRD-negative).
3.Criteria used by Zamagni et al., which, so far, was the only one showing the prognostic value of PET/CT in the MRD
setting.106 Imaging should be performed once MRD negativity is determined by MFC or NGS.
4.Bone marrow fl w cytometry should follow Next-Generation Flow (NGF) guidelines.29 The reference NGF method
is an 8 color 2 tube approach which has been extensively validated. The 2 tube approach improves reliability,
consistency and sensitivity because of the acquisition of a greater number of cells. The 8 color technology is widely
available globally and the NGF method has already been adopted in many fl w laboratories across the world. The
complete 8 color method is most effici t using the lyophilized mixture of antibodies which reduces errors, time, and
costs. It is recommended that 5 million cells be assessed. Flow cytometry method employed should have a sensitivity
of detection of plasma cells of at least 1 in 105.
5.DNA sequencing assay on marrow aspirate should use an assay such as Lymphosight® (Sequenta) since this is the
only one validated so far.
6.Derived from International uniform response criteria for multiple myeloma. Durie BG, et al. Leukemia. 2006
Sep;20(9):1467-73. Minor response definition and clarifications derived from Rajkumar SV et al. Consensus recommendations for the uniform reporting of clinical trials: report of the International Myeloma Workshop Consensus
Panel 1. Blood. 2011 May 5;117(18):4691-5. For coding CR and VGPR in patients in whom the only measurable
disease is by serum FLC levels: CR in such patients indicates a normal FLC ratio of 0.26 to 1.65 in addition to CR criteria
listed above. VGPR in such patients requires a ≥ 90% decrease in the difference between involved and uninvolved
FLC levels. All response categories require two consecutive assessments made at any time before the institution of
any new therapy; all categories also require no known evidence of progressive or new bone lesions or extramedullary
plasmacytomas if radiographic studies were performed. Radiographic studies are not required to satisfy these
response requirements. Bone marrow assessments need not be confirme . Each category, except for stable disease,
will be considered unconfirmed u til the confirm tory test is performed. The date of the initial test is considered as
the date of response for evaluation of time dependent outcomes such as duration of response.
7.Presence/absence of clonal cells on immunohistochemistry is based upon the K/L ratio. An abnormal K/L ratio by
immunohistochemistry requires a minimum of 100 plasma cells for analysis. An abnormal ratio refle ting presence
of an abnormal clone is K/L of > 4:1 or < 1:2.
8.Positive immunofix tion alone in a patient previously classified as CR will not be onsidered progression. For
purposes of calculating time to progression and progression-free survival, CR patients and MRD-negative patients
should be evaluated using criteria listed above for progressive disease (PD). Criteria for relapse from CR or relapse
from MRD should be used only when calculating DFS.
9.In the case where a value is felt to be a spurious result per physician discretion (for example, a possible lab error),
that value will not be considered when determining the lowest value.
10.All recommendations regarding clinical utilities relating to serum free light chain levels or FLC ratio is based on
results obtained with the Freelite test. Dejoie et al. have recently published a comparison of Freelite and UPEP for the
detection of the light chain component of monoclonal immunoglobulins in light chain and intact immunoglobulin
myeloma (Haematologica, published ahead of print December 3, 2015) which demonstrates the improved sensitivity
of Freelite assay over UPEP for monitoring response to treatment.
14
assays often allows a rapid assessment
of the effectiveness of treatment.
n
n
P
eople with very low levels of light
chains that are undetectable by other
tests such as SPEP, UPEP, and IFE. These
are people who generally have nonsecretory (also called hyposecretory,
oligosecretory, or paucisecretory)
myeloma. Approximately 70% of people with nonsecretory myeloma can
have their disease monitored using
the Freelite assay.
P
eople with deposits of light chains
in the form of AL amyloidosis. People
with AL amyloidosis may or may not
have active myeloma. Tracking the
light chain levels is very helpful to
assess the disease status.
n
P
eople with light chain-only (BenceJones) myeloma. The major advantages of the Freelite assay for these
people are:
l
l
Ease of blood testing versus 24-hour
urine collection. (It is important to
note that periodic 24-hour urine
testing is still recommended and
necessary, both to double-check
the light chain excretion level
and monitor for any evidence of
kidney damage.)
Greater sensitivity of blood testing.
(Mildly increased levels may be
detected in the blood but not
detected in the urine.)
What is the Hevylite assay?
The serum heavy + light chain isotype
(Hevylite) assay is a laboratory blood test
for measuring intact immunoglobulins.
It is the only automated immunoassay approved by the US Food and Drug
Administration (FDA) for monitoring
IgG and IgA myeloma. According to the
FDA approval, the Hevylite assay is to be
used for previously diagnosed myeloma
in conjunction with other clinical and
laboratory findings.
M-protein can be made up of just an immunoglobulin heavy chain (IgG, IgA, IgD, IgE,
or IgM), just a free light chain (free kappa
or lambda), or, in the majority of cases, a
heavy chain with an associated free light
chain (IgG kappa and IgG lambda, IgA
kappa and IgA lambda, etc.) as seen in
Table 1. While the Freelite test quantifies
free light chains, and has been most helpful for patients with light chain disease,
low-secreting disease, and amyloidosis,
myeloma.org
15
the Hevylite test quantifies the intact,
or whole, immunoglobulin heavy and
light chains involved in a patient’s
myeloma (IgG kappa or IgA lambda,
for example).
What is a heavy/light
chain ratio?
The Hevylite (HLC) assay recognizes
when a specific heavy chain is bound to
a specific light chain. It can distinguish
between the “involved” proteins – the
heavy and light chain produced by the
myeloma (termed iHLC) – and their “uninvolved” (i.e., normal or polyclonal – not
monoclonal, termed uHLC) counterparts
that have the same heavy chain isotype
but bound to a different light chain. An
example would be that of a patient with
IgG lambda monoclonal protein (the
“involved” heavy and light chain) and the
patient’s isotype-paired normal or “uninvolved” protein, IgG kappa. In this case,
it would be appropriate to order Hevylite
IgG lambda (the iHLC) and IgG kappa
(the uHLC). Similarly, for an IgA lambda
myeloma patient, Hevylite IgA lambda
and IgA kappa would be ordered.
Not only does the Hevylite assay calculate
the amount of iHLC and uHLC, but like
the Freelite assay, it calculates the ratio
between the involved and uninvolved
proteins (HLC ratio), and then compares
them to normal ranges for these blood
proteins. Also like the Freelite assay, the
Hevylite assay is very sensitive and is automated, so it can accurately detect monoclonal immunoglobulins at very low levels
in the blood. Hevylite values are important in assessing myeloma activity because
they accurately reveal not only the
amount of monoclonal protein (iHLC), but
the amount of normal uninvolved immunoglobulin protein (uHLC) as well. When
the uHLC is lower than normal, it demonstrates the extent to which the uHLC has
been suppressed by the myeloma.
How does the Hevylite assay
differ from SPEP?
For patients with IgA kappa or IgA lambda
myeloma, standard serum protein electrophoresis is not a particularly reliable
test. The Hevylite assay is an effective
alternative for quantifying the M-protein
of these IgA patients.
The Hevylite assay and
monitoring for relapse
The Hevylite assay can detect relapses
earlier than most other methods currently
available. If a patient’s Hevylite assay does
not produce a normal Hevylite ratio, this
is an indication that the myeloma cells
are again producing monoclonal protein.
Because the Hevylite assay is very sensitive, it can detect a relapse before it is
picked up by SPEP or IFE.
16
The Hevylite assay
and monitoring for
residual disease
What are normal
Hevylite levels?
The high sensitivity of the Hevylite assay
can also indicate the presence of minimal
residual disease (MRD) even in patients
classified as being in complete response
(CR) or stringent complete response (sCR)
by other methods. A lower than normal
level of the uninvolved HLC indicates that
there is enough myeloma present to suppress normal immune system cells, even
if the amount of abnormal (monoclonal)
protein (or iHLC) is undetectable. Early
indications from studies suggest that
patients in CR or sCR whose bone marrow
is being assessed for MRD in clinical trials
should first be screened with the Freelite
and Hevylite assays. If those sensitive
assays show abnormal Freelite and/or
Hevylite ratios, the patient is not ready for
MRD testing and should therefore delay
the bone marrow biopsy until the ratios
become normal. Bone marrow biopsy
should not be done until approximately
two months after CR is reached in order to
allow time for the bone marrow to reflect
the negative status.
Table 3. Normal Ranges for HLC Values
Each laboratory may establish local normal ranges, but for general guidance,
normal ranges for Hevylite (HLC) values
are listed in Table 3.
Can Freelite and Hevylite
be used together?
Myeloma cells from a single patient can
produce multiple clones that may produce intact immunoglobulins, free light
chains, or both. Since the free light chain
assay and the heavy + light chain isotype
assay measure independent biomarkers of disease activity, it is important to
monitor patients with both tests. Given
the heterogeneity of clones in an individual patient’s myeloma, these two assays,
when used together, are complementary.
Will insurance cover
the cost of Freelite and
Hevylite assays?
In the United States, the serum free light
chain assays are covered by Medicare
and most private insurers. Hevylite assays
are covered under the same medical
billing CPT code as Freelite; the cost to
the patient may vary, however, depending upon which laboratory performs
the testing.
HLC
Range
IgG kappa (g/L)
4.03–9.78
In closing
IgG lambda (g/L)
1.97–5.71
IgG kappa/IgG lambda ratio
0.98–2.75
IgA kappa (g/L)
0.48–2.82
IgA lambda (g/L)
0.36–1.98
IgA kappa/IgA lambda ratio
0.80–2.04
While a diagnosis of cancer is something
you cannot control, gaining knowledge
that will improve your interaction with
your doctors and nurses is something you
can control, and it will have a significant
impact on how well you do throughout
the disease course.
myeloma.org
17
This booklet is not meant to replace the
advice of your doctors and nurses, who
are best able to answer questions about
your specific healthcare management
plan. The IMF intends only to provide
you with information that will guide you
in discussions with your healthcare team.
To help ensure effective treatment with
good quality of life, you must play an
active role in your own medical care.
We encourage you to visit myeloma.org
for up-to-date information about mye
loma, and to contact the IMF InfoLine
with your myeloma-related questions and
concerns. The IMF InfoLine consistently
provides callers with the best information
about myeloma in a caring and compassionate manner. IMF InfoLine specialists
can be reached at [email protected],
or 800-452-CURE (2873) or 818-487-7455.
Terms and definitions
Bone marrow: The soft, spongy tissue in
the center of bones that produces white
blood cells, red blood cells, and platelets.
This is the tissue within which abnormal
plasma cells build up to cause myeloma.
Electrophoresis: A laboratory test in which
a patient’s serum (blood) or urine molecules are subjected to separation according to their size and electrical charge. For
myeloma patients, electrophoresis of the
blood or urine allows both the calculation
of the amount of myeloma protein (M-protein) as well as the identification of the specific M-spike characteristic for each patient.
Electrophoresis is used as a tool both for
diagnosis and for monitoring.
Extramedullary plasmacytoma: A tumor
made up of monoclonal plasma cells that
is found in soft tissue outside of the bone
marrow and separate from bone.
Flow cytometry: A technology used in
cell counting, cell sorting, and biomarker
detection by suspending cells in a stream
of fluid and passing them through a laser.
Hyposecretory: Low- or non-secreting
disease.
Immunoassay: Test used in the study
of biological systems by tracking different proteins, hormones, and antibodies.
Immunoassays rely on the inherent ability
of an antibody to bind to the specific structure of a molecule. Because antibodies are
developed to the specific three-dimensional structure of an antigen, they are
highly specific and will bind only to that
structure. ELISA (enzyme-linked immunosorbent assay) is a commonly used test to
detect antibodies in the blood.
18
Immunofixation electrophoresis (IFE):
An immunologic test of the serum or urine
used to identify proteins. For myeloma
patients, it enables the doctor to identify
the M-protein type (IgG, IgA, kappa, or
lambda). The most sensitive routine immunostaining technique, it identifies the exact
heavy and light chain type of M-protein.
Immunofluor scence: This test uses the
specificity of antibodies to their antigen to
target fluorescent dyes to specific targets
within a cell, and therefore allows visualization of the distribution of the target
molecule through the sample. Immunofluorescence makes use of fluorophores
to visualize the location of antibodies.
A fluorophore is a fluorescent chemical
compound that can re-emit light upon
light excitation. Fluorophores are used as
probes or indicators.
Immunoglobulin (Ig): A protein produced by plasma cells; an essential part of
the body’s immune system. Immunoglobulins attach to foreign substances (antigens) and assist in destroying them. The
classes (also called isotypes) of immunoglobulins are IgG, IgA, IgD, IgE, and IgM.
The non-medical word for immunoglobulin is “antibody.”
Immunohistochemistry (IHC): Immuno
histochemistry refers to the process of
detecting antigens (e.g., proteins) in cells
of a tissue section by exploiting the principle of antibodies binding specifically
to antigens in biological tissues. Immuno‑histochemical staining is widely used
in the diagnosis of abnormal cells such as
those found in cancerous tumors.
Minimal residual disease (MRD): The
presence of residual tumor cells after treatment has been completed and complete
myeloma.org
remission (CR) has been attained. Even
patients who have attained a stringent
complete response (sCR) may have MRD.
Very sensitive new testing methods are
now able to detect one myeloma cell
among one million sampled cells in blood
or bone marrow.
Monoclonal gammopathy of undeter
mined significance (MGUS): A category
of plasma cell disorder characterized by
comparatively low levels of monoclonal
protein in the blood and/or urine. Bone
marrow plasma cell levels are low (< 5%).
Myeloma-related symptoms (i.e., anemia,
renal failure, hypercalcemia, and lytic
lesions) are absent.
Monoclonal protein (M-protein): An
abnormal protein produced by myeloma
cells that accumulates in and damages
bone and bone marrow. A high level of
M-protein indicates that myeloma cells
are present in large numbers.
19
Multiple myeloma: A cancer arising from
the plasma cells in the bone marrow.
The cancerous plasma cells are called
myeloma cells.
Plasma cells: Special white blood cells
that produce antibodies (immunoglobulins). Myeloma is a cancer of the plasma
cells. Malignant plasma cells are called
myeloma cells. In myeloma, malignant
plasma cells produce large amounts of
abnormal antibodies that lack the capability to fight infection. These abnormal
antibodies are the monoclonal protein,
or M-protein, that functions as a tumor
marker for myeloma. Plasma cells also
produce other chemicals that can cause
organ and tissue damage (i.e., anemia,
kidney damage, and nerve damage).
Plasmacytoma: See “Extramedullary plasmacytoma” and “Solitary plasmacytoma of
the bone (SPB)”
Remission or response: Complete or
partial disappearance of the signs and
symptoms of cancer. Remission and
response are interchangeable terms.
• S tringent complete response (sCR) – sCR
is CR (as defined below) plus normal
FLC ratio and absence of clonal cells in
bone marrow by immunohistochemistry or immunofluorescence.
•C
omplete remission (CR) – CR is negative
immunofixation on serum and urine,
and disappearance of any soft tissue
plasmacytomas, and less than or equal
to 5% plasma cells in bone marrow. CR
is not the same as a cure.
•V
ery good partial remission (VGPR) –
VGPR is less than CR. VGPR is serum
M-protein and urine M-protein detectable by immunofixation but not on
electrophoresis, or 90% or greater
reduction in serum M-protein, plus
urine M-protein < 100 mg per 24 hours.
Notes
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•P
artial remission (PR) – PR is a level of
response in which there is at least a 50%
reduction in M-protein, and reduction
in 24-hour urinary M-protein by at least
90% (or to less than 200 mg/24 hrs).
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Solitary plasmacytoma of bone (SPB):
A discreet, single mass of monoclonal
plasma cells in a bone. The diagnosis
of SBP requires a solitary bone lesion,
a biopsy of which shows infiltration by
plasma cells; negative imaging results
for other bone lesions; absence of clonal
plasma cells in a random sample of bone
marrow; and no evidence of anemia,
hypercalcemia, or renal involvement suggesting systemic myeloma.
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The printing of this patient education booklet was
supported by a grant from The Binding Site.
20
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myeloma.org
21
Notes
10 STEPS TO BETTER CARE®
________________________________________________________________________
A UNIQUE TOOL FOR DIAGNOSTIC
AND TREATMENT INFORMATION
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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One of the most daunting aspects of being diagnosed with multiple myeloma
(MM) is learning about – and understanding – an unfamiliar disease that is quite
complicated. From diagnosis to long-term survival, the 10 Steps to Better Care® will
guide you through the MM journey:
________________________________________________________________________
1. Know what you’re dealing with. Get the correct diagnosis.
2. Tests you really need.
3. Initial treatment options.
________________________________________________________________________
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4. Supportive care and how to get it.
________________________________________________________________________
5. Transplant: Do you need one?
________________________________________________________________________
6. Response Assessment: Is treatment working?
7. Consolidation and/or maintenance.
8. Keeping Track of the Myeloma: Monitoring without mystery.
9. Relapse: Do you need a change in treatment?
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10. New Trials: How to find them.
Visit 10steps.myeloma.org to gain a better understanding of the disease and
diagnosis, and proceed through the steps to learn the best tests, treatments,
supportive care, and clinical trials currently available.
As always, the International Myeloma Foundation (IMF) urges you to discuss all
medical issues thoroughly with your doctor. The IMF is here to equip you with
the tools to understand and better manage your MM. Visit the IMF website at
myeloma.org or call the IMF InfoLine at 800-452-CURE (2873) or 818-487-7455 to
speak with our trained information specialists about your questions or concerns.
The IMF is here to help.

Understanding Serum Free Light Chain Assays

Transcription

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