To the editor:

A mutation in myeloid differentiation factor gene, MYD88, leading to constitutive activation of the nuclear factor κB pathway was shown to be oncogenically active in 29% of patients with activated B-cell type diffuse large B-cell lymphoma.1  The most common somatic variant of MYD88 mutation is substitution of leucine by proline at position 265 (L265P)1  because of a single nucleotide change (T→C) in chromosome 3p22.2.2  Subsequently, MYD88L265P was discovered in 86% to 100% of patients with Waldenström macroglobulinemia (WM)/lymphoplasmacytic lymphoma,2-4  10% to 87% of immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance (MGUS),2-6  36% to 38% of primary central nervous system lymphoma,7,8  6% to 21% of splenic marginal zone lymphoma,3,4,6  9% of gastric mucosa associated lymphoid tissue lymphomas, and 2.9% to 4% of those with chronic lymphocytic leukemia.3,9 MYD88 is an adaptor protein that drives tumor growth by increased Toll-like receptor and interleukin-1 receptor signaling upon activation of its Toll interleukin-1 receptor domain. This leads to homodimerization and activation of interleukin-1 receptor associated kinase 1 and 4,1  as well as transforming growth factor-β associated kinase-1.10 

A risk stratification model in patients with IgM MGUS has predicted an increased 5- and 10-year cumulative incidence of progression to WM or other lymphoproliferative disorders (LPDs) in those harboring MYD88L265P mutation, compared with wild-type variants (5- and 10-year risk of 15% and 45% vs 2% and 14%, respectively).11  Although primary systemic amyloidosis is associated with clonal plasma cell proliferative disorders or B-cell LPDs,12  the frequency of an activating MYD88 mutation has not been studied in this population thus far. In a study by Jiménez et al,6  patients with light chain (AL) amyloidosis were reported to be negative for MYD88L265P 6. However, isotype of the monoclonal protein was not reported. The objective of our study was to detect the frequency of activating MYD88 mutation in IgM amyloidosis cases and identify clinicopathologic correlations, if any.

We report data on 15 bone marrow tissue specimens, which were obtained from 14 patients with archival tissue available from the transplant database in Mayo Clinic after approval by the Institutional Review Board. All samples were examined by standard morphology and flow cytometric evaluation of B cells and plasma cells compartments. All available clinical and pathologic data were reviewed.

DNA was extracted from CD138+ or CD19+CD138+ sorted cells isolated from the bone marrows of IgM amyloidosis patients using the Gentra PureGene DNA Isolation Kit (Qiagen, Valencia, CA). Real-time allele-specific oligonucleotide polymerase chain reaction was performed using qBiomarker Somatic Mutation Assay for MYD88_85940 (SABiosciences-Qiagen, Hilden, Germany) according to the manufacturer’s protocol. The reverse transcription polymerase chain reaction was analyzed using CFX96 real-time thermal cycler (Bio-Rad, Hercules, CA). To obtain a ΔΔCt range for wild-type alleles, the assay was performed on DNA from 10 MYD88WT controls. The cutoff for wild-type vs mutant MYD88 was a ΔΔCt value of 0.003.10 

Clinical and demographic characteristics of each patient has been summarized in Table 1. Ten out of 14 patients (71%) were positive for the MYD88L265P mutation. Median age of the study population was 60 years (range 48-70 years). Four MYD88L265P-positive patients (patients 1, 7, 8, and 10) had a prior diagnosis of WM. Three patients (patients 3, 9, and 13) had biclonal gammopathy on immunofixation. Among MYD88L265P-positive patients, bone marrow examination revealed clonal plasma cells in 8 patients (patients 1, 2, 3, 5, 7, 8, 9, and 10), clonal B lymphocytes in 9 patients (patients 1, 2, 4, 5, 6, 7, 8, 9, and 10), and both clonal B lymphocytes and plasma cells in 7 patients (patients 1, 2, 5, 7, 8, 9, and 10). Of note, 9/10 patients with MYD88L265P had clonal B lymphocytes in bone marrow, as opposed to 1/4 patient with MYD88WT. Conventional karyotype analysis showed normal karyotype in all patients. Cytogenetic analysis by fluorescent in situ hybridization was done in 8 out of 14 patients. Among MYD88L265P-positive patients (5 evaluable patients), 1 patient had trisomy 9, monosomy 13, and deletion of IgH variable region; 1 had normal fluorescent in situ hybridization cytogenetics; and 3 had insufficient plasma cells for analysis. Among MYD88WT patients (3 evaluable patients), 2 patients had t(11;14) and 1 had insufficient plasma cells for analysis. Median serum M-spike in MYD88L265P and MYD88WT patients was 1.15 g/dL (range 0.24-2.3 g/dL) and 0.55 g/dL (range 0.1-0.9 g/dL), respectively. Cardiac involvement was seen in 1 out of 10 patients with MYD88L265P and 2 out of 4 patients with MYD88WT. Nervous system involvement (peripheral and/or autonomic) was seen in 4 out of 10 patients with MYD88L265P and 0 out of 4 patients with MYD88WT.

Table 1

Clinical and pathologic characteristics of study patients

Patient no.Age (y)/ sexMYD88 L265P mutationOrgans involved2012 Revised Mayo AL amyloidosis stageMonoclonal protein in serumUrine total protein (g/24 h)Clonal cells in bone marrow*OS from diagnosis (mo)Progression
Isotypeg/dLY/NPFS (mo)
68/F Positive Peripheral nervous system II IgM λ 2.4 0.05 Clonal B lymphocytes and clonal plasma cells 109 76 
70/M Positive Peripheral and autonomic nervous system IgM λ 0.9 0.98 Clonal B lymphocytes and clonal plasma cells 43 43 
63/F Positive Spleen and kidney IgM λ IgA λ 0.3 8.87 Clonal plasma cells 83 28 
52/M Positive Peripheral and central nervous system IgM κ 0.5 0.08 Clonal B lymphocytes 78 67 
48/F Positive Kidney and autonomic nervous system II IgM κ 1.5 3.65 Clonal B lymphocytes and clonal plasma cells 62 48 
65/M Positive Lungs and lymph node IgM λ 1.4 0.06 Clonal B lymphocytes 41 33 
56/M Positive Lymph nodes and soft tissue IgM κ 1.6 0.12 Clonal plasma cells and clonal B lymphocytes 26 26 
65/M Positive Kidney IgM κ 2.4 9.59 Clonal plasma cells and clonal B lymphocytes 30 30 
60/M Positive Kidney IgM κ IgM λ 1.1 1.66 Clonal plasma cells and clonal B lymphocytes 12 12 
10 60/M Positive Heart and tongue III IgM κ 1.1 0.07 Clonal B lymphocytes and clonal plasma cells 21 21 
11 62/F Negative Kidney IgM κ 0.6 5.90 Clonal plasma cells 104 104 
12 53/M Negative Kidney, heart and gastrointestinal tract III IgM κ 0.1 34.9 Clonal plasma cells 16 14 
13 60/M Negative Heart, lymph nodes, and tongue II IgM κ IgM λ 0.5 0.20 Clonal plasma cells 120 120 
14 56/M Negative Kidney IgM λ 0.9 6.19 Clonal plasma cells and clonal B lymphocytes 55 55 
Patient no.Age (y)/ sexMYD88 L265P mutationOrgans involved2012 Revised Mayo AL amyloidosis stageMonoclonal protein in serumUrine total protein (g/24 h)Clonal cells in bone marrow*OS from diagnosis (mo)Progression
Isotypeg/dLY/NPFS (mo)
68/F Positive Peripheral nervous system II IgM λ 2.4 0.05 Clonal B lymphocytes and clonal plasma cells 109 76 
70/M Positive Peripheral and autonomic nervous system IgM λ 0.9 0.98 Clonal B lymphocytes and clonal plasma cells 43 43 
63/F Positive Spleen and kidney IgM λ IgA λ 0.3 8.87 Clonal plasma cells 83 28 
52/M Positive Peripheral and central nervous system IgM κ 0.5 0.08 Clonal B lymphocytes 78 67 
48/F Positive Kidney and autonomic nervous system II IgM κ 1.5 3.65 Clonal B lymphocytes and clonal plasma cells 62 48 
65/M Positive Lungs and lymph node IgM λ 1.4 0.06 Clonal B lymphocytes 41 33 
56/M Positive Lymph nodes and soft tissue IgM κ 1.6 0.12 Clonal plasma cells and clonal B lymphocytes 26 26 
65/M Positive Kidney IgM κ 2.4 9.59 Clonal plasma cells and clonal B lymphocytes 30 30 
60/M Positive Kidney IgM κ IgM λ 1.1 1.66 Clonal plasma cells and clonal B lymphocytes 12 12 
10 60/M Positive Heart and tongue III IgM κ 1.1 0.07 Clonal B lymphocytes and clonal plasma cells 21 21 
11 62/F Negative Kidney IgM κ 0.6 5.90 Clonal plasma cells 104 104 
12 53/M Negative Kidney, heart and gastrointestinal tract III IgM κ 0.1 34.9 Clonal plasma cells 16 14 
13 60/M Negative Heart, lymph nodes, and tongue II IgM κ IgM λ 0.5 0.20 Clonal plasma cells 120 120 
14 56/M Negative Kidney IgM λ 0.9 6.19 Clonal plasma cells and clonal B lymphocytes 55 55 

F, female; M, male.

*

Clonality was assessed by immunohistochemistry and flow cytometry from bone marrow specimens.

Calculated using serum troponin T, N-terminal pro–brain natriuretic peptide, and difference between involved and uninvolved free light chains.

Patients alive.

Estimated median-follow up of surviving patients was 77.9 months (95% confidence interval [CI], 26.3-120.3 months). Median overall survival (OS) and progression-free survival (PFS) from diagnosis for the entire cohort was 95.8 months (95% CI, 41.2 to not reached [NR]) and 48.2 months (95% CI, 27.8-120.3), respectively. Median OS in patients with MYD88L265P and MYD88WT was 83.0 months (95% CI, 11.9-108.6) and NR (95% CI, 16.4-NR), respectively, 5-year OS rates being 60% (95% CI, 24% to 87%) and 75% (95% CI, 24% to 97%), respectively. Median PFS in patients with MYD88L265P and MYD88WT was 43.3 months (95% CI, 11.9-75.7) and 120.3 months (95% CI, 14.0-120.3), respectively. Statistical significance was not achieved for comparison between the 2 groups, likely because of small sample size. Clinical characteristics and outcomes of the entire cohort has been summarized in Table 2.

Table 2

Clinical characteristics of patients by MYD88 mutational status

Clinical characteristicsOverall (n = 14)MYD88L265P (n = 10)MYD88WT (n = 4)
Median age, y (range) 60 (48-70) 61.5 (48-70) 58 (53-62) 
Median serum M-spike, g/dL (range) 0.9 (0.1-2.4) 1.15 (0.24-2.4) 0.55 (0.1-0.9) 
Cardiac involvement (n) 
Peripheral or autonomic neuropathy (n) 
Median OS, mo (95% CI) 95.8 (41.2-NR) 83.0 (11.9-108.6) NR (16.4-NR) 
Median PFS 48.2 (27.8-120.3) 43.3 (11.9-75.7) 120.3 (14.0-120.3) 
Clinical characteristicsOverall (n = 14)MYD88L265P (n = 10)MYD88WT (n = 4)
Median age, y (range) 60 (48-70) 61.5 (48-70) 58 (53-62) 
Median serum M-spike, g/dL (range) 0.9 (0.1-2.4) 1.15 (0.24-2.4) 0.55 (0.1-0.9) 
Cardiac involvement (n) 
Peripheral or autonomic neuropathy (n) 
Median OS, mo (95% CI) 95.8 (41.2-NR) 83.0 (11.9-108.6) NR (16.4-NR) 
Median PFS 48.2 (27.8-120.3) 43.3 (11.9-75.7) 120.3 (14.0-120.3) 

IgM-associated AL amyloidosis is a distinct clinical entity, constituting 5% to 7% of all AL amyloidosis cases.13,14  They are usually characterized by older age at onset, higher incidence of peripheral neuropathy and lymphadenopathy, with no survival difference from non-IgM cases.14  A study by Landgren and Staudt showing the presence of MYD88L265P by Sanger sequencing in 56% of patients with IgM MGUS had demonstrated the presence of clonal plasma cells and clonal lymphocytes in all patients positive for this mutation.5  In our study, all but 1 MYD88L265P-positive patient had clonal B lymphocyte in marrow, likely indicating association of MYD88L265P mutation with LPDs. MYD88L265P-positive patients had a lower rate of cardiac involvement (1/10; 10%), compared with an expected rate of 32% to 40%14,15  in patients with IgM amyloidosis. On the other hand, a higher incidence of amyloid neuropathy (4/10; 40%) was seen in these patients. One MYD88L265P-positive patient (patient 4) had multiple cranial nerve palsies, an unusual manifestation of amyloidosis. In patients with WM, MYD88L265P mutation was shown to be associated with a higher disease burden in bone marrow and peripheral blood, poor response to therapy, and inferior OS.16,17  It is unclear whether an activating MYD88 mutation is a driver for increased amyloid deposition by the plasma cell clone and whether presence of these mutations in patients with B-cell LPDs entails an increased risk for development of systemic IgM amyloidosis. Given the ease of detection of MYD88L265P mutation, studies should focus on assessing its frequency in larger cohorts of B-cell LPDs and correlating with clinical characteristics, including the development of systemic amyloidosis. A novel oligonucleotide, IMO-8400, which acts by inhibiting activated Toll-like receptor signaling pathway in patients with MYD88L265P mutation, is currently being tested in patients with WM/lymphoplasmacytic lymphoma (#NCT02092909) and activated B-cell type diffuse large B-cell lymphoma (#NCT02252146). Preclinical studies in mice have shown antiproliferative activity of inhibitors of MYD88 dimerization (ST2825),18  which could create novel therapeutic avenues for IgM amyloidosis in the future.

Authorship

Contribution: R.C., M.A.G., and A.J.N. designed the study, analyzed the data, wrote the first draft, and approved the final version of the manuscript; M.A.G., S.M.A., A.D., M.Q.L., S.R.H., P.K., F.K.B., and R.L.K. performed patient management, revised the manuscript critically, and participated in final data analysis and approval of the final version of the manuscript; E.M. analyzed data, provided critical review of the manuscript, and approved the final version of the manuscript.

Conflict-of-interest disclosure: The authors declare no competing financial interests.

Correspondence: Morie A. Gertz, Mayo Clinic, 200 S.W. First St, W10, Rochester, MN 55905; e-mail: gertz.morie@mayo.edu.

References

References
1
Ngo
 
VN
Young
 
RM
Schmitz
 
R
, et al. 
Oncogenically active MYD88 mutations in human lymphoma.
Nature
2011
, vol. 
470
 
7332
(pg. 
115
-
119
)
2
Treon
 
SP
Xu
 
L
Yang
 
G
, et al. 
MYD88 L265P somatic mutation in Waldenström’s macroglobulinemia.
N Engl J Med
2012
, vol. 
367
 
9
(pg. 
826
-
833
)
3
Xu
 
L
Hunter
 
ZR
Yang
 
G
, et al. 
MYD88 L265P in Waldenström macroglobulinemia, immunoglobulin M monoclonal gammopathy, and other B-cell lymphoproliferative disorders using conventional and quantitative allele-specific polymerase chain reaction [published correction appears in Blood. 2013;121(26):5259].
Blood
2013
, vol. 
121
 
11
(pg. 
2051
-
2058
)
4
Varettoni
 
M
Arcaini
 
L
Zibellini
 
S
, et al. 
Prevalence and clinical significance of the MYD88 (L265P) somatic mutation in Waldenstrom’s macroglobulinemia and related lymphoid neoplasms.
Blood
2013
, vol. 
121
 
13
(pg. 
2522
-
2528
)
5
Landgren
 
O
Staudt
 
L
MYD88 L265P somatic mutation in IgM MGUS.
N Engl J Med
2012
, vol. 
367
 
23
(pg. 
2255
-
2256, author reply 2256-2257
)
6
Jiménez
 
C
Sebastián
 
E
Chillón
 
MC
, et al. 
MYD88 L265P is a marker highly characteristic of, but not restricted to, Waldenström’s macroglobulinemia.
Leukemia
2013
, vol. 
27
 
8
(pg. 
1722
-
1728
)
7
Bruno
 
A
Boisselier
 
B
Labreche
 
K
, et al. 
Mutational analysis of primary central nervous system lymphoma.
Oncotarget
2014
, vol. 
5
 
13
(pg. 
5065
-
5075
)
8
Montesinos-Rongen
 
M
Godlewska
 
E
Brunn
 
A
Wiestler
 
OD
Siebert
 
R
Deckert
 
M
Activating L265P mutations of the MYD88 gene are common in primary central nervous system lymphoma.
Acta Neuropathol
2011
, vol. 
122
 
6
(pg. 
791
-
792
)
9
Puente
 
XS
Pinyol
 
M
Quesada
 
V
, et al. 
Whole-genome sequencing identifies recurrent mutations in chronic lymphocytic leukaemia.
Nature
2011
, vol. 
475
 
7354
(pg. 
101
-
105
)
10
Ansell
 
SM
Hodge
 
LS
Secreto
 
FJ
, et al. 
Activation of TAK1 by MYD88 L265P drives malignant B-cell growth in non-Hodgkin lymphoma.
Blood Cancer J
2014
, vol. 
4
 
2
pg. 
e183
 
11
Varettoni
 
M
Zibellini
 
S
Arcaini
 
L
, et al. 
MYD88 (L265P) mutation is an independent risk factor for progression in patients with IgM monoclonal gammopathy of undetermined significance.
Blood
2013
, vol. 
122
 
13
(pg. 
2284
-
2285
)
12
Kyle
 
RA
Gertz
 
MA
Primary systemic amyloidosis: clinical and laboratory features in 474 cases.
Semin Hematol
1995
, vol. 
32
 
1
(pg. 
45
-
59
)
13
Palladini
 
G
Russo
 
P
Bosoni
 
T
, et al. 
AL amyloidosis associated with IgM monoclonal protein: a distinct clinical entity.
Clin Lymphoma Myeloma
2009
, vol. 
9
 
1
(pg. 
80
-
83
)
14
Gertz
 
MA
Buadi
 
FK
Hayman
 
SR
IgM amyloidosis: clinical features in therapeutic outcomes.
Clin Lymphoma Myeloma Leuk
2011
, vol. 
11
 
1
(pg. 
146
-
148
)
15
Sissoko
 
M
Sanchorawala
 
V
Seldin
 
D
, et al. 
Clinical presentation and treatment responses in IgM-related AL amyloidosis.
Amyloid
2015
, vol. 
22
 
4
(pg. 
229
-
235
)
16
Treon
 
SP
Cao
 
Y
Xu
 
L
Yang
 
G
Liu
 
X
Hunter
 
ZR
Somatic mutations in MYD88 and CXCR4 are determinants of clinical presentation and overall survival in Waldenstrom macroglobulinemia.
Blood
2014
, vol. 
123
 
18
(pg. 
2791
-
2796
)
17
Patkar
 
N
Subramanian
 
PG
Deshpande
 
P
, et al. 
MYD88 mutant lymphoplasmacytic lymphoma/Waldenström macroglobulinemia has distinct clinical and pathological features as compared to its mutation negative counterpart.
Leuk Lymphoma
2015
, vol. 
56
 
2
(pg. 
420
-
425
)
18
Loiarro
 
M
Capolunghi
 
F
Fantò
 
N
, et al. 
Pivotal advance: inhibition of MyD88 dimerization and recruitment of IRAK1 and IRAK4 by a novel peptidomimetic compound.
J Leukoc Biol
2007
, vol. 
82
 
4
(pg. 
801
-
810
)