Elevated Serum Free Light Chains Are Associated With Event-Free and Overall Survival in Two Independent Cohorts of Patients With Diffuse Large B-Cell Lymphoma

Article (PDF Available)inJournal of Clinical Oncology 29(12):1620-6 · March 2011with71 Reads
DOI: 10.1200/JCO.2010.29.4413 · Source: PubMed
Abstract
The serum free light chain (FLC) assay quantitates free kappa (κ) and free lambda (λ) immunoglobulin light chains. This assay has prognostic value in plasma cell proliferative disorders. There are limited data on serum FLC in B-cell malignancies. The association of pretreatment FLC with event-free survival (EFS) and overall survival (OS) in diffuse large B-cell lymphoma (DLBCL) was evaluated in 76 patients from the North Central Cancer Treatment Group trial N0489 (NCT00301821) and 219 patients from the University of Iowa/Mayo Clinic Specialized Program of Research Excellence Molecular Epidemiology Resource (MER). Published reference ranges were used to define an elevated FLC or an abnormal κ:λ FLC ratio. Elevated FLC or abnormal κ:λ FLC ratio was present in 32% and 14% of patients, respectively. Patients with elevated FLC had an inferior OS and EFS in both cohorts compared with patients with normal FLC (N0489: EFS hazard ratio [HR], 3.06; OS HR, 3.16; both P < .02; MER: EFS HR, 2.42; OS HR, 3.40; both P < .001; combined EFS HR, 2.57; OS HR, 3.74; both P < .001). All associations remained significant for EFS and OS after adjusting for the International Prognostic Index (IPI). Abnormal κ:λ FLC ratio was modestly associated with outcome in the combined group (EFS HR, 1.61; OS HR, 1.67; both P = .07), but not in patients without corresponding elevated κ or λ. Elevated FLC was the strongest predictor of outcome in multivariable models with the IPI components. Increased serum FLC is an independent, adverse prognostic factor for EFS and OS in DLBCL and warrants further evaluation as a biomarker in DLBCL.
Elevated Serum Free Light Chains Are Associated With
Event-Free and Overall Survival in Two Independent
Cohorts of Patients With Diffuse Large B-Cell Lymphoma
Matthew J. Maurer, Ivana N.M. Micallef, James R. Cerhan, Jerry A. Katzmann, Brian K. Link,
Joseph P. Colgan, Thomas M. Habermann, David J. Inwards, Svetomir N. Markovic, Stephen M. Ansell,
Luis F. Porrata, Patrick B. Johnston, Grzegorz S. Nowakowski, Carrie A. Thompson, Mamta Gupta,
Sergei I. Syrbu, Paul J. Kurtin, William R. Macon, Daniel A. Nikcevich, and Thomas E. Witzig
From the Mayo Clinic College of Medi-
cine and Mayo Foundation, Rochester;
Duluth Community Clinical Oncology
Program, Duluth, MN; and University of
Iowa, Iowa City, IA.
Submitted March 19, 2010; accepted
November 18, 2010; published online
ahead of print at www.jco.org on
March 7, 2011.
This study was conducted as a collabor-
ative trial of the North Central Cancer
Treatment Group and Mayo Clinic and
was supported in part by Public Health
Service Grants No. CA-25224,
CA-37404, CA-35269, CA-35431, CA-
35267, CA-63849, CA-35103,
CA-35101, CA-35113, CA-35195,
CA-35090, CA-37417, and CA-35119
from the National Cancer Institute,
Department of Heath and Human
Services; by North Central Cancer
Treatment Group Biospecimen
Resource Grant No. CA-114740; by
Grant No. CA97274 (University of Iowa/
Mayo Clinic Lymphoma Specialized
Program of Research Excellence); and
by the Henry J. Predolin Foundation.
The content of this article is solely the
responsibility of the authors and does
not necessarily represent the official
views of the National Cancer Institute
or the National Institutes of Health.
Presented in part at the American Soci-
ety of Hematology, New Orleans, LA,
December 5-8, 2009.
Authors’ disclosures of potential con-
flicts of interest and author contribu-
tions are found at the end of this
article.
Clinical Trials repository link available on
JCO.org.
Corresponding author: Thomas E.
Witzig, MD, Mayo Clinic, Stabile 628,
200 First St SW, Rochester, MN 55905;
e-mail: Witzig@mayo.edu.
© 2011 by American Society of Clinical
Oncology
0732-183X/11/2912-1620/$20.00
DOI: 10.1200/JCO.2010.29.4413
ABSTRACT
Purpose
The serum free light chain (FLC) assay quantitates free kappa (
) and free lambda (
) immuno-
globulin light chains. This assay has prognostic value in plasma cell proliferative disorders. There
are limited data on serum FLC in B-cell malignancies.
Patients and Methods
The association of pretreatment FLC with event-free survival (EFS) and overall survival (OS) in
diffuse large B-cell lymphoma (DLBCL) was evaluated in 76 patients from the North Central Cancer
Treatment Group trial N0489 (NCT00301821) and 219 patients from the University of Iowa/Mayo
Clinic Specialized Program of Research Excellence Molecular Epidemiology Resource (MER).
Published reference ranges were used to define an elevated FLC or an abnormal
:
FLC ratio.
Results
Elevated FLC or abnormal
:
FLC ratio was present in 32% and 14% of patients, respectively.
Patients with elevated FLC had an inferior OS and EFS in both cohorts compared with patients with
normal FLC (N0489: EFS hazard ratio [HR], 3.06; OS HR, 3.16; both P .02; MER: EFS HR, 2.42; OS
HR, 3.40; both P .001; combined EFS HR, 2.57; OS HR, 3.74; both P .001). All associations
remained significant for EFS and OS after adjusting for the International Prognostic Index (IPI).
Abnormal
:
FLC ratio was modestly associated with outcome in the combined group (EFS HR, 1.61;
OS HR, 1.67; both P .07), but not in patients without corresponding elevated
or
. Elevated FLC
was the strongest predictor of outcome in multivariable models with the IPI components.
Conclusion
Increased serum FLC is an independent, adverse prognostic factor for EFS and OS in DLBCL and
warrants further evaluation as a biomarker in DLBCL.
J Clin Oncol 29:1620-1626. © 2011 by American Society of Clinical Oncology
INTRODUCTION
Diffuse large B-cell lymphoma (DLBCL) is the
most common non-Hodgkin’s lymphoma (NHL)
in the United States. Standard treatment for
newly diagnosed DLBCL is rituximab and an
anthracycline-based chemotherapy regimen, usu-
ally cyclophosphamide, doxorubicin, vincristine,
and prednisone.
1,2
The move to an immunochem-
otherapy approach has improved the event-free
(EFS) and overall survival (OS) rates in DLBCL.
The International Prognostic Index (IPI) is a clin-
ical prognostic score developed for aggressive
lymphoma in the chemotherapy treatment era.
2
Based on five clinical variables, it remains associ-
ated with outcome in the immunochemotherapy
era, although its general prognostic ability is mod-
est.
3
There is a need for additional prognostic
markers in DLBCL to better identify patients who
will relapse after immunochemotherapy or fail to
achieve a remission. Gene-expression profiling
studies have suggested that DLBCL may have sev-
eral phenotypes, generally characterized by tu-
mors expressing either a germinal center signal or
activated B-cell signal.
4
Several algorithms and
gene sets have been developed to distinguish these
tumor phenotypes and identify tumors with
either a good or poor prognosis.
5,6
Despite the
active research in these areas, risk-adaptive treat-
ment approaches based on tumor phenotype or
other prognostics are still in the development
stage at this time.
JOURNAL OF CLINICAL ONCOLOGY
ORIGINAL REPORT
VOLUME 29 NUMBER 12 APRIL 20 2011
1620 © 2011 by American Society of Clinical Oncology
The free light chain (FLC) assay measures the concentration in
the serum of immunoglobulin kappa (
) and lambda (
) light
chains that are not attached to a heavy chain.
7
Abnormalities in
FLC are associated with plasma cell disorders.
8
These abnormali-
ties are monoclonal in nature and result in one of the chains being
elevated, often substantially, producing an abnormal
:
ratio. As
such, the serum FLC assay has demonstrated utility for screening,
diagnosis, prognosis, and response assessment in multiple myelo-
ma, monoclonal gammopathy of undetermined significance, and
AL-amyloidosis.
9-13
Elevation of FLC may also be secondary to a
number of disease states associated with B-cell hyperplasia and
immune stimulation.
14
These elevations tend to be polyclonal and
do not result in an abnormal
:
ratio. In addition, patients with
renal impairment may demonstrate a polyclonal increase of serum
FLC from a reduced capacity to clear the normal FLC from
the blood.
15
There are limited data on FLC in lymphoma and chronic lym-
phocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). We
previously reported that FLC abnormalities were present in 13% of
208 patients with lymphoma, with abnormal
:
FLC prevalence
varying from 0% to 36% by lymphoma type.
16
The prevalence of
abnormal
:
FLC ratio was lowest in DLBCL (8%) and highest in
mantle-cell lymphoma (36%) and CLL/SLL (24%); however, these
results were based on only 25 patients of each NHL type. In a large
series of 259 patients with CLL, Pratt et al
17
reported 39% of patients
had an abnormal FLC ratio and these patients had an inferior OS. This
association with an adverse OS was confirmed in another cohort of
patients with CLL.
18
A recent study by Landgren et al
19
found an
association of elevated serum FLC with the risk of NHL in 291 indi-
viduals infected with HIV. In the studies of FLC in NHL by Martin
16
and Landgren et al,
19
no information on the role of FLC relative to
outcome was presented. We report herein the largest study of serum
FLC in a lymphoid malignancy to date and present the first report of
FLC and outcome in DLBCL, to our knowledge, from two indepen-
dent cohorts of patients.
PATIENTS AND METHODS
Study Population
This study was reviewed and approved by the human subjects institu-
tional review board at the Mayo Clinic and the University of Iowa, and written
informed consent was obtained from all participants. Patients in the first
cohort were from the North Central Cancer Treatment Group clinical trial
N0489 (NCT00301821); the second cohort was comprised of patients enrolled
in the Molecular Epidemiology Resource (MER) of the University of Iowa/
Mayo Clinic LymphomaSpecialized Program of Research Excellence (SPORE;
CA97274). N0489 was a phase II trial of epratuzumab and rituximab plus
cyclophosphamide, doxorubicin, vincristine, and prednisone for patients with
newly, diagnosed, untreated DLBCL.
20,21
Patients selected from the SPORE
MER had newly diagnosed DLBCL and were managed off-study using stan-
dard treatment regimens for DLBCL.
The diagnosis of DLBCL was confirmed by the study hematopathologist
(N0489: P.J.K.; MER: W.R.M. or S.I.S.) in all patients.
22
Baseline clinical,
laboratory, and treatment data were abstracted from medical records using
a standard protocol (MER) or per the N0489 clinical trial protocol. MER
participants provided an on-study peripheral blood sample for serum and
DNA banking; N0489 patients had research serum drawn pretreatment, at
restaging (after cycles 2 and 6), and every 3 months for 1 year. All patients
were systematically followed every 6 months for the first 3 years, and then
annually thereafter (MER) or every 3 months in year 1, every 4 months in
year 2, and every 6 months in years 3 to 5 (N0489). Disease progression,
re-treatment, and deaths were verified through medical record review. For
decedents, we obtained a copy of the death certificate as well as medical
records associated with death. Tumor response was measured using the
International Working Group response criteria
23,24
on the N0489 clinical
trial; in the MER response was not assessed per the clinical trial protocol,
thus response was not used for this analysis.
One hundred seven patients were enrolled on North Central Cancer
Treatment Group N0489 from February 2006 through August 2007; 24 were
excluded for lack of serum sample and seven were excluded for not having
DLBCL, leaving 76 patients for analysis. Two hundred nineteen patients with
DLBCL with a pretreatment serum draw were enrolled into the MER from
September 2002 through February 2008 and used in this analysis.
Serum FLC Measurements
The FREELITE assay (The Binding Site Ltd, Birmingham, United King-
dom) was used to measure serum
and
FLC concentrations and the
:
FLC
ratio.
7,25
The FLC assays were performed by the Mayo Clinic Clinical Immu-
nology Lab using kits provided courtesy of The Binding Site. Abnormal
:
FLC ratio was a priori defined as a
:
FLC ratio outside of (0.26, 1.65) and
elevated FLC as a
concentration higher than 1.94 mg/dL or
concentration
higher than 2.63 mg/dL based on the published normal ranges for Mayo
Medical Laboratories
25
and as used in previous studies.
9-19
Statistical Analyses
The primary analysis was to assess the association of FLC concentrations
and abnormal
:
FLC ratio with EFS and OS for DLBCL. FLC concentrations
(
,
, and total FLC) were examined as continuous variables on the log scale.
For analysis purposes, due to the biologic potential for a monoclonal increase
in one light chain but not the other, elevated FLC was defined as having a
and/or
concentration above the established Mayo Medical Laboratories
normal range. EFS was defined as the time from diagnosis to disease progres-
sion, re-treatment, or death due to any cause. OS was defined as the time from
diagnosis to death due to any cause. Patients without an event or death were
censored at time of last known follow-up. The local reference range was used to
determine the upper limit of normal for clinically abstracted lab values. Cox
proportional hazards regression models
26
were used to assess the association of
FLC and outcome via unadjusted and IPI-adjusted hazard ratios (HR). Cox
models on the combined data set were stratified by cohort. Kaplan-Meier
27
curves were used to graphically display the association of FLC with outcome.
We also assessed the association of FLC and outcome using the continuously
distributed FLC concentrations via penalized smoothing splines, or
P-splines.
27a
Logistic regression models were used to assess the association of
FLC abnormalities with clinical characteristics via cohort-adjusted odds ratios.
The prognostic capability of models were assessed with time dependent re-
ceiver operating characteristic curves; the area under the curve and concor-
dance indices (C indices) were determined per the approach of Heagerty and
Zheng
28
with bootstrap CIs used to assess the significance of differences.
Analyses were performed using SAS version 9.1.3 (SAS Institute, Cary, NC)
and R version 2.7.1 (R Project http://www.r-project.org/).
RESULTS
Patient characteristics were generally similar between the two co-
horts with the N0489 group having more patients with stage III/IV
disease and more than two extranodal sites (Table 1). Median
follow-up was 26.2 months (range, 7.5 to 40.8 months) in N0489
with 21 events and 17 deaths. Median follow-up was 34.9 months
(range, 4.9 to 74.8 months) in the MER with 74 events and 57
deaths. Overall
and
measurements were similar in the two
cohorts (Fig 1). In N0489, 34% had an elevated FLC and 12% of
patients had an abnormal
:
FLC ratio; in the MER cohort, 31%
and 15% had an elevated FLC and abnormal
:
FLC ratio, respec-
tively. Across both cohorts, elevated FLC was associated with older
FLC for Large Cell Lymphoma
www.jco.org
© 2011 by American Society of Clinical Oncology 1621
age, worse performance status, advanced stage, and elevated creat-
inine, although association with the IPI was modest (Table 2).
An increase in serum FLC was univariately associated with EFS
and OS in both cohorts for
(all P .05),
(all P .02), and total FLC
(all P .002) measurements (Appendix Table A1, Appendix Figs
A1A-A1F, online only). Patients with elevation of either FLC had an
inferior OS and EFS compared to patients with normal-range serum
and
FLC (N0489: EFS HR, 3.06; OS HR, 3.16; both P .02; MER:
EFS HR, 2.42; OS HR, 3.40; both P .001; combined EFS HR, 2.57;
OS HR, 3.74; both P .001; Table 3; Fig 2). The results remained
significant for EFS and OS after adjusting for IPI in N0489 (both P
.02), MER (both P .001), and when both groups were combined
(both P .001). Furthermore, in a combined analysis, elevated FLC
was associated with EFS and OS in all four IPI classification subsets
(Appendix Table A2, online only; all P .08).
Abnormal
:
FLC ratio was modestly associated with outcome
in the combined group (EFS HR, 1.61; OS HR, 1.67; both P .07;
Table 3). However, this was solely due to patients with an elevated
FLC. In patients with normal range
and
concentrations, abnormal
:
FLC ratio was not associated with outcome (EFS HR, 1.00; OS HR,
1.00; both P .99; Appendix Table A2).
Elevated FLC was highly associated with elevated serum creati-
nine, with 58% of patients with an elevated creatinine having an
elevated FLC compared to 29% of patients with normal creatinine
having elevated FLCs. The association of FLC and outcome strength-
ened in the subset of 241 patients with normal creatinine (EFS HR,
2.71; OS HR, 4.09; both P .001), while elevated FLC was not
associated with outcome in the 40 patients with elevated creatinine
Table 1. Clinical Characteristics of the Patients With New, Untreated Diffuse Large B-Cell Lymphoma Enrolled Onto This Study
Characteristic
NCCTG N0489 (n 76) SPORE MER (n 219) All Patients (N 295)
No. % No. % No. %
Median age, years 62 64 62
Range 21-82 21-93 21-93
Male sex 43 56.6 117 53.4 160 54.2
Age 60 years 43 56.6 131 59.8 174 59.0
Performance status 2 11 14.5 42 19.2 53 18.0
Ann Arbor stage III/IV 61 80.3 126 58.1 187 63.8
Two or more extranodal sites 25 32.9 46 21.4 71 24.4
LDH ULN 52 68.4 103 48.4 155 53.6
IPI
0-1 18 23.7 79 36.1 97 23.9
2 17 22.4 59 26.9 76 25.8
3 28 36.8 49 22.4 77 26.1
4-5 13 17.1 32 14.6 45 15.3
B symptoms 29 38.2 46 21.0 75 25.4
Bulky disease 13 17.1 26 11.9 39 13.3
Bone marrow involvement 9 11.8 29 14.3 38 13.6
Creatinine ULN 12 15.8 28 13.4 40 14.0
Immunochemotherapy 76 100 186 85.3 262 89.1
Median FLC
Kappa 1.53 1.48 1.50
Range 0.73-5.57 0.02-45.7 0.02-45.7
Lambda 1.69 1.44 1.51
Range 0.43-15.2 0.20-11.8 0.20-15.2
Total FLC 3.27 2.93 3.08
Range 1.48-19.1 0.37-51.1 0.37-51.1
Abnormal FLC ratio 9 11.8 32 14.8 41 14.0
Elevated FLC 26 34.2 68 31.1 94 31.9
Elevated kappa 23 30.3 63 28.8 86 29.2
Elevated lambda 11 14.5 29 13.2 40 13.6
Abbreviations: NCCTG, North Central Cancer Treatment Group; SPORE, Specialized Program of Research Excellence; MER, Molecular Epidemiology Resource;
LDH, lactate dehydrogenase; ULN, upper limit of normal; IPI, International Prognostic Index; FLC, free light chain.
0.1
MER
N0489
Lambda mg/dL
Kappa mg/dL
100
10
1
1 10 100
Fig 1. Pretreatment serum free light chain values (mg/dL) from North Central Cancer
Treatment Group N0489 and Specialized Program of Research Excellence Molecular
Epidemiology Resource (MER) cohorts. Dashed box indicates normal range.
Maurer et al
1622
© 2011 by American Society of Clinical Oncology
J
OURNAL OF CLINICAL ONCOLOGY
(n 40; EFS HR, 1.24; OS HR, 1.00; both P .60; Appendix Table
A2). In general, the inferior EFS and OS for patients with elevated FLC
was similar whether the elevated FLC was due to a monoclonal (ab-
normal FLC ratio) or polyclonal (normal FLC ratio with or without
elevated creatinine) light chain expansion (Appendix Figs A2A and
A2B, online only).
In a multivariable analysis with the five IPI components, ele-
vated FLC was the variable most strongly associated with both EFS
(HR, 2.26; P ⫽⬍.001) and OS (HR, 2.5; P .001); stage and
number of extranodal sites were no longer predictive for EFS and
OS in the multivariable models (all P .30; Table 3). A risk model
including elevated FLC in a risk model with the other IPI compo-
nents resulted in a higher prognostic ability over the first 36 months
compared to the IPI for both EFS (36-month C index, 0.667 v 0.606
respectively; 95% bootstrap CI for difference, 0.019 to 0.100) and OS (36
month C index, 0.721 v 0.658, respectively; 95% bootstrap CI for differ-
ence, 0.016 to 0.113; Appendix Figs A3A and A3B, online only).
Serum FLC was reduced significantly by treatment in the N0489
clinical trial, with reductions in total FLC during treatment observed
in 100% of patients having both a pretreatment and postcycle 2 (n
47) or postcycle 6 (n 52) draw. Median reduction in total FLC was
42% and 57% after 2 and 6 cycles of treatment, respectively. In the 21
patients with elevated pretreatment FLC and follow-up samples, 18
(86%) achieved a normalization of their serum FLC following either
cycle 2 or cycle 6.
Tumor light chain restriction status was available on the submit-
ted N0489 on-study pathology reports for 14 patients (18%). Ten
patients had
-restricted tumors and four had
-restricted tumors.
Seven (50%) of 14 patients had an abnormal
:
FLC ratio, of which
four also had elevated FLC. Eleven patients had both pretreatment and
Table 2. Association of Clinical Characteristics With FLC Abnormalities
Characteristic No. % Elevated FLC OR 95% CI P % Abnormal
:
Ratio OR 95% CI P
All patients 295 31.9 14.0
Sex
Female 135 28.2 1.00 11.9 1.00
Male 160 35.0 1.37 0.83 to 2.25 .21 15.7 1.39 0.71 to 2.72 .34
Age, years
60 121 20.7 1.00 11.7 1.00
60 174 39.7 2.52 1.48 to 4.37 .001 15.6 1.40 0.70 to 2.80 .34
Performance status
0-1 242 26.9 1.00 13.3 1.00
2 53 54.7 3.29 1.79 to 6.06 .001 17.3 1.37 0.61 to 3.07 .45
Ann Arbor stage
I-II 106 24.5 1.00 10.4 1.00
III-IV 187 35.8 1.72 1.01 to 2.93 .05 16.2 1.67 0.80 to 3.49 .17
Extranodal sites, No.
0-1 220 32.3 1.00 16.5 1.00
2 71 28.2 0.82 0.46 to 1.48 .52 7.0 0.38 0.14 to 1.02 .05
LDH
ULN 134 33.6 1.00 15.7 1.00
ULN 155 31.0 0.89 0.54 to 1.46 .64 13.1 0.81 0.42 to 1.57 .53
B symptoms
Absent 220 30.0 1.00 12.3 1.00
Present 75 37.3 1.39 0.80 to 2.41 .24 18.9 1.66 0.82 to 3.67 .16
Bulky disease
Absent 255 31.0 1.00 14.6 1.00
Present 39 38.5 1.39 0.69 to 2.80 .35 10.3 0.67 0.22 to 1.99 .47
Bone marrow involvement
No 241 29.5 1.00 12.5 1.00
Yes 38 36.8 1.40 0.68 to 2.86 .36 24.3 2.25 0.67 to 5.23 .06
Creatinine
ULN 245 28.6 1.00 12.4 1.00
ULN 40 57.5 3.38 1.70 to 6.71 .005 25.0 2.37 1.05 to 5.33 .04
Treatment
Immunochemotherapy 262 30.5 0.62 0.30 to 1.36 .25 13.9 0.87 0.31 to 2.40 .78
Other 32 40.6 1.00 15.6 1.00
IPI
0-1 97 22.7 1.00 10.3 1.00
2 76 34.2 1.77 0.91 to 3.47 .09 19.7 2.14 0.90 to 5.08 .08
3 77 37.7 2.06 1.06 to 3.99 .03 16.0 1.66 0.67 to 4.08 .27
4-5 45 37.8 2.07 0.96 to 4.46 .06 8.9 0.85 0.25 to 2.87 .79
0-2 173 27.8 1.00 14.5 1.00
3-5 122 37.7 1.58 0.96 to 2.59 .07 13.3 0.91 0.46 to 1.79 .79
Abbreviations: FLC, free light chain; OR, odds ratio; LDH, lactate dehydrogenase; ULN, upper limit of normal; IPI, International Prognostic Index.
FLC for Large Cell Lymphoma
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© 2011 by American Society of Clinical Oncology 1623
post-treatment (cycle 6) serum draws. Patients had a significantly
greater reduction in the serum light chain that corresponded with
the light chain restricted in the tumor (median reduction, 1.07
mg/dL; range, 0.58 to 6.03) compared with the nontumor-
restricted light chain (median reduction, 0.43 mg/dL; range, 0.09
to 1.76; rank sum P .03). Also, one of the patients with an
identified
-restricted tumor presented with highly elevated
and
normal
(Appendix Fig A4, online only). The
remained normal
and unchanged during treatment, while the
was reduced into
normal range after two cycles of treatment. The patient achieved a
positron emission tomography complete response after six cycles
of treatment and remained in remission through 9 months of
observation with stable FLC concentrations on follow-up samples.
However, at 12 months post-treatment the serum
FLC increased
(with normal
FLC) and tumor imaging and biopsy revealed
tumor relapse. While based on a single patient, this case provides
additional evidence that the tumor is directly influencing the cor-
responding light chain in the serum.
DISCUSSION
Serum FLC abnormalities are prevalent in patients with DLBCL,
with 32% having elevated
or
concentrations and 14% of pa-
tients having an abnormal
:
FLC ratio. The most important
parameter associated with outcome appears to be the absolute
concentration of FLC rather than the
:
ratio. Increased serum
FLC was strongly associated with an inferior outcome and re-
mained significant after adjusting for IPI. Abnormal
:
FLC ratio,
however, was only modestly associated with outcome across all
patients, with the association only related to a concomitant ele-
vated FLC. Patients with abnormal
:
FLC ratio without an ele-
vation of either chain should be considered normal for risk. We
defined elevated FLC as a concentration above the published nor-
mal range for either
and/or
. This definition captures patients
with either a monoclonal or polyclonal FLC expansion, as outcome
was similarly poor for each type of FLC expansion (Appendix Figs
A2A and A2B). Examination of the hazard ratio across the contin-
uous range of each light chain (Appendix Fig A1) shows an increase
in risk for high values of
,
, as well as total FLC.
Strengths of this study include the large number of patients
studied all with a uniform type of NHL, patients treated in the
immunochemotherapy era, and replication of study results from
both a cooperative group clinical trial and a clinic-based registry.
FLC assessment was done in a single clinical lab with extensive
experience with the assay.
8,9,11,25
Assays were performed longitu-
dinally on identically treated patients from the clinical trial to
Table 3. EFS and OS Cox Proportional Hazards Models
Model
EFS OS
HR 95% CI P HR 95% CI P
Univariate
Abnormal
:
ratio
NCCTG N0489
Unadjusted 1.87 0.63 to 5.55 .26 2.58 0.84 to 7.91 .1
Adjusted for IPI 2.22 0.76 to 7.20 .14 3.82 1.17 to 12.53 .03
MER
Unadjusted 1.54 0.86 to 2.77 .14 1.49 0.78 to 2.81 .22
Adjusted for IPI 1.51 0.85 to 2.71 .16 1.45 0.77 to 2.74 .25
Combined
Unadjusted 1.61 0.96 to 2.69 .07 1.67 0.96 to 2.91 .07
Adjusted for IPI 1.67 0.99 to 2.79 .05 1.75 1.00 to 3.06 .05
Elevated FLC
NCCTG
Unadjusted 3.06 1.28 to 7.29 .01 3.16 1.20 to 8.32 .02
Adjusted for IPI 3.00 1.26 to 7.16 .01 3.22 1.22 to 8.50 .02
MER
Unadjusted 2.42 1.53 to 3.82 .001 3.40 2.02 to 5.75 .001
Adjusted for IPI 2.17 1.37 to 3.44 .001 2.84 1.67 to 4.83 .001
Combined
Unadjusted 2.57 1.72 to 3.85 .001 3.74 2.13 to 5.35 .001
Adjusted for IPI 2.37 1.58 to 3.55 .001 2.94 1.85 to 4.77 .001
Multivariable
Elevated FLC 2.26 1.44 to 5.48 .001 2.53 1.53 to 4.24 .001
Age 60 years 1.56 0.97 to 2.52 .07 1.92 1.08 to 3.41 .03
PS 2 1.64 0.98 to 2.73 .06 2.40 1.39 to 4.16 .002
Two or more extranodal sites 1.02 0.59 to 1.75 .95 1.17 0.65 to 2.09 .61
Stage III/IV 1.23 0.74 to 2.05 .42 1.37 0.76 to 2.49 .30
LDH ULN 1.53 0.96 to 2.42 .07 1.60 0.95 to 2.71 .08
Abbreviations: EFS, event-free survival; OS, overall survival; HR, hazard ratio; NCCTG, North Central Cancer Treatment Group; IPI, International Prognostic Index;
MER, Molecular Epidemiology Resource; FLC, free light chain; PS, performance status; LDH, lactate dehydrogenase; ULN, upper limit of normal.
Multivariable model simultaneously assessing elevated FLC with the variables for the five IPI components.
Maurer et al
1624
© 2011 by American Society of Clinical Oncology
J
OURNAL OF CLINICAL ONCOLOGY
assess the influence of treatment on FLC concentrations. Limita-
tions of the study include the low percentage of clinical trial pa-
tients with data on tumor light chain restriction and limited
follow-up time on these two cohorts of patients.
There are several plausible causes of elevated FLC in patients with
DLBCL. Host effects, such as renal dysfunction,
15
advanced age, or
immune disruption or stimulation
14
can cause a polyclonal increase in
serum FLC. We observed this in our study, as elevated FLC was
significantly associated with elevated creatinine and older age. Ele-
vated FLC was observed in 57% of patients with elevated creatinine;
however, the association of FLC and outcome was actually strength-
ened when the subset of patients with normal renal creatinine was
evaluated, suggesting the association of FLC and outcome in our study
was not an artifact of renal function. The tumor is another likely cause
of elevated FLC in DLBCL. Most DLBCL tumors are immunoglobulin
light chain restricted and we would expect that the clonal expansion of
the neoplastic B-cell may cause an increase in the corresponding light
chain in the serum. Because
:
FLC ratios in normal individuals can
be either
predominant or
predominant, it is difficult to assess the
relationship of tumor and serum light chain without knowing the
patient’s
:
FLC ratio before lymphoma. However, in the serial data
on the clinical trial, there was a greater reduction in the FLC concen-
tration of the tumor-associated serum light chain during treatment,
suggesting the tumor drives the excess of the residual light chain that is
detected in serum.
Regardless of cause, patients with elevated FLC have similarly
poor outcome. This was true in both high-risk and low-risk patients,
as FLC was associated with outcome in all IPI categories. Potential
reasons for this poor outcome are multiple and may vary from patient
to patient. Patients with severe renal insufficiency would be expected
to have both elevated polyclonal FLC and poor outcome due to
nontumor-related comorbidities. We also saw an association of ele-
vated FLC with poor performance status and elevated FLC may be a
marker of general host frailty. Landgren et al
19
recently showed in-
creased FLC to be associated with an increased risk of AIDS-related
lymphoma. They hypothesize this may represent a generalized disrup-
tion of B-cell function leading to increased risk of NHL development.
A similar polyclonal state may result in a favorable microenvironment
for the tumor or lead to a reduced host antitumor response. Elevated
FLC may also be a marker of disease burden. We found an association
of elevated FLC with stage in our study. More notably however, when
FLC is included in a multivariable model with the IPI components,
FLC is the largest single predictor of outcome. Stage and number of
extranodal sites are no longer predictive of outcome in a model in-
cluding FLC, and an index with FLC, performance status, age, and
lactate dehydrogenase has more prognostic ability than the traditional
IPI model. Finally, elevated FLC may perhaps be associated with a
more aggressive tumor.
In summary, elevated FLC concentrations are associated with
poor outcome in patients with DLBCL and is independent of the IPI.
Our data suggest FLC may provide a better measure of disease burden
for prognosis than stage and number of extranodal sites. If these
results can be confirmed in additional data sets, the serum FLC assay
has the potential to become a new, easily measured, serum biomarker
for predicting prognosis in DLBCL. In addition, it may be used serially
at times of follow-up to provide clues to relapse. Additional studies of
serum FLC and outcome are warranted in this patient population and
further studies are needed to better understand the mechanisms of
elevated FLC in DLBCL.
AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS
OF INTEREST
Although all authors completed the disclosure declaration, the following
author(s) indicated a financial or other interest that is relevant to the subject
matter under consideration in this article. Certain relationships marked
with a “U” are those for which no compensation was received; those
relationships marked with a “C” were compensated. For a detailed
description of the disclosure categories, or for more information about
ASCO’s conflict of interest policy, please refer to the Author Disclosure
Declaration and the Disclosures of Potential Conflicts of Interest section in
Information for Contributors.
Employment or Leadership Position: None Consultant or Advisory
Role: None Stock Ownership: None Honoraria: None Research
Funding: Jerry A. Katzmann, The Binding Site Expert Testimony: None
Other Remuneration: None
AUTHOR CONTRIBUTIONS
Conception and design: Matthew J. Maurer, James R. Cerhan, Brian K.
Link, Thomas M. Habermann, Thomas E. Witzig
0
Nonelevated FLC - N0489
Nonelevated FLC - MER
Elevated FLC - N0489
Elevated FLC - MER
Event-Free Survival (%)
A
Time (months)
100
80
60
40
20
12 24 36 48 60
0
Overall Survival (%)
B
Time (months)
100
80
60
40
20
12 24 36 48 60
Nonelevated FLC - N0489
Nonelevated FLC - MER
Elevated FLC - N0489
Elevated FLC - MER
Fig 2. (A) Event-free survival and (B) overall survival Kaplan-Meier survival
curves by serum free light chain (FLC) in two cohorts (North Central Cancer
Treatment Group trial N0489 and the Specialized Program of Research Excel-
lence Molecular Epidemiology Resource [MER]) of patients with untreated
diffuse large B-cell lymphoma.
FLC for Large Cell Lymphoma
www.jco.org © 2011 by American Society of Clinical Oncology 1625
Financial support: James R. Cerhan
Administrative support: James R. Cerhan, Thomas M. Habermann
Provision of study materials or patients: Ivana N.M. Micallef, James R.
Cerhan, Brian K. Link, Joseph P. Colgan, David J. Inwards, Svetomir N.
Markovic, Stephen M. Ansell, Patrick B. Johnston, Grzegorz S.
Nowakowski, Carrie A. Thompson, Sergei I. Syrbu, William R. Macon,
Daniel A. Nikcevich, Thomas E. Witzig
Collection and assembly of data: Matthew J. Maurer, James R. Cerhan, Jerry A.
Katzmann, Thomas M. Habermann, Paul J. Kurtin, Thomas E. Witzig
Data analysis and interpretation: Matthew J. Maurer, James R. Cerhan,
Jerry A. Katzmann, Thomas M. Habermann, Stephen M. Ansell,
Thomas E. Witzig
Manuscript writing: All authors
Final approval of manuscript: All authors
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    • "In addition, we analysed a more homogenous group of patients with respect to age (61– 80 years) and Eastern Cooperative Oncology Group performance status (ECOG PS, 0–2) than Maurer et al (2011), who found an association of elevated FLC with older age (range 21–93 years) and inferior performance status (ECOG PS > 2). It has been suggested that monoclonal FLC are secreted by lymphoma cells (Maurer et al, 2011) and their presence might therefore indicate malignant transformation in a certain stage of B-cell differentiation (Campo et al, 2011). In our study, there was no association of FLC abnormalities with any morphological lymphoma subtype or with GCB or non-GCB lymphoma according to the Hans classifier. "
    Full-text · Article · Jun 2014
    • "In 2011 Maurer et al [16], showed that increased serum FLC, present in 32% of DLBCL was an independent adverse prognostic factor. More recently, after the introduction of a new sensitive method for immunoglobulin heavy chain detection, a prospective study showed elevated IgMκ or IgMλ or an abnormal IgMκ/IgMλ ratio to occur in 9.3% and 19.1% of DLBCL respectively [17]. "
    [Show abstract] [Hide abstract] ABSTRACT: Recently, diffuse-large-B-cell lymphoma (DLBCL) associated with serum IgM monoclonal component (MC) has been shown to be a very poor prognostic subset although, detailed pathological and molecular data are still lacking. In the present study, the clinicopathological features and survival of IgM-secreting DLBCL were analyzed and compared to non-secreting cases in a series of 151 conventional DLBCL treated with R-CHOP. IgM MC was detected in 19 (12.5%) out of 151 patients at disease onset. In 17 of these cases secretion was likely due to the neoplastic clone, as suggested by the expression of heavy chain IgM protein in the cytoplasm of tumor cells. In IgM-secreting cases immunoblastic features (p
    Full-text · Article · Apr 2014
  • [Show abstract] [Hide abstract] ABSTRACT: Free light chains (FLCs) are the most commonly detected paraproteins in chronic lymphocytic leukemia (CLL). We examined the types of FLC abnormalities and prognostic utility of the FLC assay compared with standard prognostic biomarkers in a prospective cohort of 339 patients with newly diagnosed CLL. Three types of FLC abnormalities were identified: monoclonal elevated FLC (elevated κ and/or λ with abnormal FLC ratio), polyclonal elevated FLC (elevated κ and/or λ with normal FLC ratio), and ratio-only FLC abnormality (normal range κ and λ with abnormal FLC ratio). One hundred sixty-five patients (49%) had a FLC abnormality with approximately equal distribution among monoclonal elevation, polyclonal elevation, and ratio-only abnormality. All FLC abnormalities were associated with poor time to first treatment: monoclonal FLC (hazard ratio [HR], 4.99; 95% confidence interval [CI], 2.94-8.48), polyclonal FLC (HR, 2.40; 95% CI, 1.24-4.64), ratio-only FLC (HR, 2.57; 95% CI, 1.40-4.69). Monoclonal FLC and polyclonal FLC were associated with poor overall survival compared with patients with normal FLC. Results remained significant after adjusting for Rai stage. The FLC assay is a simple, widely available clinical test with similar prognostic utility as routinely used prognostic biomarkers for CLL. Among persons with FLC abnormalities, the type of abnormality affects prognostic significance.
    Full-text · Article · Jul 2011
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