Follicular lymphoma is the most common indolent lymphoma, with a favorable prognosis and survival measured in decades. However, approximately 15% to 20% of patients encounter early disease progression, termed POD24, within 24 months from diagnosis or treatment initiation. Recognizing the correlation between POD24 and a heightened risk of lymphoma-related death has sparked intensive investigations into the clinical and biological determinants of POD24 and the development of innovative treatment strategies targeting this group. Research is also ongoing to understand the varying impact of POD24 based on different clinical contexts and the implications of early histologic transformation on POD24 prognosis. Recent investigations have uncovered potential new predictors of POD24, including genetic and nongenetic alterations as well as some conflicting F-fludeoxyglucose–positron emission tomography characteristics such as maximum standardized uptake value and total metabolic tumor volume. These developments, together with clinical predictors, have led to the emergence of several clinicopathologic tools to help identify at diagnosis patients who may be at higher risk for POD24. As these models are not routinely used, more work is needed to develop new risk-stratification strategies integrating clinical and molecular risk profiling that can be easily implemented in clinical practice to drive therapeutic choice. This review aims to delineate the modest but incremental progress achieved in our understanding of POD24, both clinically and biologically. Furthermore, we offer insights into the best practices to approach POD24 in the current era, aspiring to chart a new path forward to optimize patient outcomes.

1.
Casulo
C
,
Byrtek
M
,
Dawson
KL
, et al.
Early relapse of follicular lymphoma after rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone defines patients at high risk for death: an analysis from the National LymphoCare Study
.
J Clin Oncol
.
2015
;
33
(
23
):
2516
-
2522
.
2.
Maurer
MJ
,
Bachy
E
,
Ghesquières
H
, et al.
Early event status informs subsequent outcome in newly diagnosed follicular lymphoma
.
Am J Hematol
.
2016
;
91
(
11
):
1096
-
1101
.
3.
Jurinovic
V
,
Kridel
R
,
Staiger
AM
, et al.
Clinicogenetic risk models predict early progression of follicular lymphoma after first-line immunochemotherapy
.
Blood
.
2016
;
128
(
8
):
1112
-
1120
.
4.
Weibull
CE
,
Wästerlid
T
,
Wahlin
BE
, et al.
Survival by first-line treatment type and timing of progression among follicular lymphoma patients: a National Population-based Study in Sweden
.
Hemasphere
.
2023
;
7
(
3
):
e838
.
5.
Casulo
C
,
Dixon
JG
,
Le-Rademacher
J
, et al.
Validation of POD24 as a robust early clinical end point of poor survival in FL from 5225 patients on 13 clinical trials
.
Blood
.
2022
;
139
(
11
):
1684
-
1693
.
6.
Seymour
JF
,
Marcus
R
,
Davies
A
, et al.
Association of early disease progression and very poor survival in the GALLIUM study in follicular lymphoma: benefit of obinutuzumab in reducing the rate of early progression
.
Haematologica
.
2019
;
104
(
6
):
1202
-
1208
.
7.
Lansigan
F
,
Barak
I
,
Pitcher
B
, et al.
The prognostic significance of PFS24 in follicular lymphoma following firstline immunotherapy: a combined analysis of 3 CALGB trials
.
Cancer Med
.
2019
;
8
(
1
):
165
-
173
.
8.
Freeman
CL
,
Kridel
R
,
Moccia
AA
, et al.
Early progression after bendamustine-rituximab is associated with high risk of transformation in advanced stage follicular lymphoma
.
Blood
.
2019
;
134
(
9
):
761
-
764
.
9.
Zelenetz
AD
,
Gordon
LI
,
Abramson
JS
, et al.
NCCN Guidelines® Insights: B-cell lymphomas, Version 6.2023
.
J Natl Compr Canc Netw
.
2023
;
21
(
11
):
1118
-
1131
.
10.
Dreyling
M
,
Ghielmini
M
,
Rule
S
, et al.
Newly diagnosed and relapsed follicular lymphoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
.
Ann Oncol
.
2021
;
32
(
3
):
298
-
308
.
11.
Morin
RD
,
Mendez-Lago
M
,
Mungall
AJ
, et al.
Frequent mutation of histone-modifying genes in non-Hodgkin lymphoma
.
Nature
.
2011
;
476
(
7360
):
298
-
303
.
12.
Pasqualucci
L
,
Dominguez-Sola
D
,
Chiarenza
A
, et al.
Inactivating mutations of acetyltransferase genes in B-cell lymphoma
.
Nature
.
2011
;
471
(
7337
):
189
-
195
.
13.
Milpied
P
,
Gandhi
AK
,
Cartron
G
, et al.
Follicular lymphoma dynamics
.
Adv Immunol
.
2021
;
150
:
43
-
103
.
14.
Ochiai
K
,
Maienschein-Cline
M
,
Simonetti
G
, et al.
Transcriptional regulation of germinal center B and plasma cell fates by dynamical control of IRF4
.
Immunity
.
2013
;
38
(
5
):
918
-
929
.
15.
Willis
SN
,
Good-Jacobson
KL
,
Curtis
J
, et al.
Transcription factor IRF4 regulates germinal center cell formation through a B cell-intrinsic mechanism
.
J Immunol
.
2014
;
192
(
7
):
3200
-
3206
.
16.
Crotty
S.
T follicular helper cell differentiation, function, and roles in disease
.
Immunity
.
2014
;
41
(
4
):
529
-
542
.
17.
Saito
M
,
Gao
J
,
Basso
K
, et al.
A signaling pathway mediating downregulation of BCL6 in germinal center B cells is blocked by BCL6 gene alterations in B cell lymphoma
.
Cancer Cell
.
2007
;
12
(
3
):
280
-
292
.
18.
Akkaya
M
,
Kwak
K
,
Pierce
SK
.
B cell memory: building two walls of protection against pathogens
.
Nat Rev Immunol
.
2020
;
20
(
4
):
229
-
238
.
19.
Mesin
L
,
Ersching
J
,
Victora
GD
.
Germinal center B cell dynamics
.
Immunity
.
2016
;
45
(
3
):
471
-
482
.
20.
Pasqualucci
L
,
Khiabanian
H
,
Fangazio
M
, et al.
Genetics of follicular lymphoma transformation
.
Cell Rep
.
2014
;
6
(
1
):
130
-
140
.
21.
Schroers-Martin
JG
,
Soo
J
,
Brisou
G
, et al
;
EPIC Consortium
.
Tracing founder mutations in circulating and tissue-resident follicular lymphoma precursors
.
Cancer Discov
.
2023
;
13
(
6
):
1310
-
1323
.
22.
Zhang
J
,
Dominguez-Sola
D
,
Hussein
S
, et al.
Disruption of KMT2D perturbs germinal center B cell development and promotes lymphomagenesis
.
Nat Med
.
2015
;
21
(
10
):
1190
-
1198
.
23.
Ortega-Molina
A
,
Boss
IW
,
Canela
A
, et al.
The histone lysine methyltransferase KMT2D sustains a gene expression program that represses B cell lymphoma development
.
Nat Med
.
2015
;
21
(
10
):
1199
-
1208
.
24.
Mondello
P
,
Tadros
S
,
Teater
M
, et al.
Selective inhibition of HDAC3 targets synthetic vulnerabilities and activates immune surveillance in lymphoma
.
Cancer Discov
.
2020
;
10
(
3
):
440
-
459
.
25.
Jiang
Y
,
Ortega-Molina
A
,
Geng
H
, et al.
CREBBP inactivation promotes the development of HDAC3-dependent lymphomas
.
Cancer Discov
.
2017
;
7
(
1
):
38
-
53
.
26.
Béguelin
W
,
Popovic
R
,
Teater
M
, et al.
EZH2 is required for germinal center formation and somatic EZH2 mutations promote lymphoid transformation
.
Cancer Cell
.
2013
;
23
(
5
):
677
-
692
.
27.
Ennishi
D
,
Takata
K
,
Béguelin
W
, et al.
Molecular and genetic characterization of MHC deficiency identifies ezh2 as therapeutic target for enhancing immune recognition
.
Cancer Discov
.
2019
;
9
(
4
):
546
-
563
.
28.
Green
MR
,
Kihira
S
,
Liu
CL
, et al.
Mutations in early follicular lymphoma progenitors are associated with suppressed antigen presentation
.
Proc Natl Acad Sci U S A
.
2015
;
112
(
10
):
E1116
-
E1125
.
29.
Yuan
S
,
Almagro
J
,
Fuchs
E.
Beyond genetics: driving cancer with the tumour microenvironment behind the wheel
.
Nat Rev Cancer
.
2024
;
24
(
4
):
274
-
286
.
30.
Mondello
P
,
Ansell
SM
,
Nowakowski
GS
.
Immune epigenetic crosstalk between malignant B cells and the tumor microenvironment in B cell lymphoma
.
Front Genet
.
2022
;
13
:
826594
.
31.
Liu
Q
,
Silva
A
,
Kridel
R.
Predicting early progression in follicular lymphoma
.
Ann Lymphoma
.
2021
;
5
:
11
.
32.
Casulo
C
,
Larson
MC
,
Flowers
CR
, et al.
The FLIPI24 prognostic model identifies poor outcomes in non-immunochemotherapy treated patients with follicular lymphoma
.
Blood
.
2023
;
142
(
suppl 1
):
1657
.
33.
Maurer
MJ
,
Prochazka
VK
,
Flowers
CR
, et al.
FLIPI24: an improved international prognostic model developed on early events in follicular lymphoma
.
Blood
.
2022
;
140
(
suppl 1
):
2292
-
2295
.
34.
Pastore
A
,
Jurinovic
V
,
Kridel
R
, et al.
Integration of gene mutations in risk prognostication for patients receiving first-line immunochemotherapy for follicular lymphoma: a retrospective analysis of a prospective clinical trial and validation in a population-based registry
.
Lancet Oncol
.
2015
;
16
(
9
):
1111
-
1122
.
35.
Huet
S
,
Tesson
B
,
Jais
JP
, et al.
A gene-expression profiling score for prediction of outcome in patients with follicular lymphoma: a retrospective training and validation analysis in three international cohorts
.
Lancet Oncol
.
2018
;
19
(
4
):
549
-
561
.
36.
Inoue
T
,
Shinnakasu
R
,
Ise
W
,
Kawai
C
,
Egawa
T
,
Kurosaki
T.
The transcription factor Foxo1 controls germinal center B cell proliferation in response to T cell help
.
J Exp Med
.
2017
;
214
(
4
):
1181
-
1198
.
37.
Mzoughi
S
,
Fong
JY
,
Papadopoli
D
, et al.
PRDM15 is a key regulator of metabolism critical to sustain B-cell lymphomagenesis
.
Nat Commun
.
2020
;
11
(
1
):
3520
.
38.
Ruan
H
,
Wang
Z
,
Zhai
Y
, et al.
Single-cell transcriptome analysis of diffuse large B cells in cerebrospinal fluid of central nervous system lymphoma
.
iScience
.
2021
;
24
(
9
):
102972
.
39.
Weisel
FJ
,
Zuccarino-Catania
GV
,
Chikina
M
,
Shlomchik
MJ
.
A temporal switch in the germinal center determines differential output of memory B and plasma cells
.
Immunity
.
2016
;
44
(
1
):
116
-
130
.
40.
Bolen
CR
,
Mattiello
F
,
Herold
M
, et al.
Treatment dependence of prognostic gene expression signatures in de novo follicular lymphoma
.
Blood
.
2021
;
137
(
19
):
2704
-
2707
.
41.
Dave
SS
,
Wright
G
,
Tan
B
, et al.
Prediction of survival in follicular lymphoma based on molecular features of tumor-infiltrating immune cells
.
N Engl J Med
.
2004
;
351
(
21
):
2159
-
2169
.
42.
Mondello
P
,
Fama
A
,
Larson
MC
, et al.
Lack of intrafollicular memory CD4 + T cells is predictive of early clinical failure in newly diagnosed follicular lymphoma
.
Blood Cancer J
.
2021
;
11
(
7
):
130
.
43.
Tobin
JWD
,
Keane
C
,
Gunawardana
J
, et al.
Progression of disease within 24 months in follicular lymphoma is associated with reduced intratumoral immune infiltration
.
J Clin Oncol
.
2019
;
37
(
34
):
3300
-
3309
.
44.
Haebe
S
,
Shree
T
,
Sathe
A
, et al.
Single-cell analysis can define distinct evolution of tumor sites in follicular lymphoma
.
Blood
.
2021
;
137
(
21
):
2869
-
2880
.
45.
Han
G
,
Deng
Q
,
Marques-Piubelli
ML
, et al.
Follicular lymphoma microenvironment characteristics associated with tumor cell mutations and MHC class II expression
.
Blood Cancer Discov
.
2022
;
3
(
5
):
428
-
443
.
46.
Cheson
BD
,
Fisher
RI
,
Barrington
SF
, et al
;
United Kingdom National Cancer Research Institute
.
Recommendations for initial evaluation, staging, and response assessment of Hodgkin and non-Hodgkin lymphoma: the lugano classification
.
J Clin Oncol
.
2014
;
32
(
27
):
3059
-
3068
.
47.
Barrington
SF
,
Mikhaeel
NG
,
Kostakoglu
L
, et al.
Role of imaging in the staging and response assessment of lymphoma: consensus of the international conference on malignant lymphomas imaging working group
.
J Clin Oncol
.
2014
;
32
(
27
):
3048
-
3058
.
48.
Schöder
H
,
Noy
A
,
Gönen
M
, et al.
Intensity of 18fluorodeoxyglucose uptake in positron emission tomography distinguishes between indolent and aggressive non-Hodgkin's lymphoma
.
J Clin Oncol
.
2005
;
23
(
21
):
4643
-
4651
.
49.
Noy
A
,
Schöder
H
,
Gönen
M
, et al.
The majority of transformed lymphomas have high standardized uptake values (SUVs) on positron emission tomography (PET) scanning similar to diffuse large B-cell lymphoma (DLBCL)
.
Ann Oncol
.
2009
;
20
(
3
):
508
-
512
.
50.
Bodet-Milin
C
,
Kraeber-Bodéré
F
,
Moreau
P
,
Campion
L
,
Dupas
B
,
Le Gouill
S.
Investigation of FDG-PET/CT imaging to guide biopsies in the detection of histological transformation of indolent lymphoma
.
Haematologica
.
2008
;
93
(
3
):
471
-
472
.
51.
Karam
M
,
Feustel
PJ
,
Vera
CD
,
Nazeer
T.
Features of large cell transformation of indolent lymphomas as observed on sequential PET/CT
.
Nucl Med Commun
.
2011
;
32
(
3
):
177
-
185
.
52.
Blase
PE
,
Pasker-de Jong
PCM
,
Hagenbeek
A
,
Fijnheer
R
,
de Haas
MJ
,
de Klerk
JMH
.
Predictive potential of FDG-PET/CT for histological transformation in patients with indolent lymphoma
.
2014
;
04
(
01
):
1
-
10
.
53.
Strati
P
,
Ahmed
MA
,
Fowler
NH
, et al.
Pre-treatment maximum standardized uptake value predicts outcome after frontline therapy in patients with advanced stage follicular lymphoma
.
Haematologica
.
2020
;
105
(
7
):
1907
-
1913
.
54.
Mir
F
,
Barrington
SF
,
Brown
H
, et al.
Baseline SUVmax did not predict histological transformation in follicular lymphoma in the phase 3 GALLIUM study
.
Blood
.
2020
;
135
(
15
):
1214
-
1218
.
55.
Tychyj-Pinel
C
,
Ricard
F
,
Fulham
M
, et al.
PET/CT assessment in follicular lymphoma using standardized criteria: central review in the PRIMA study
.
Eur J Nucl Med Mol Imaging
.
2014
;
41
(
3
):
408
-
415
.
56.
Cottereau
AS
,
Versari
A
,
Chartier
L
, et al.
Low SUVmax measured on baseline FDG-PET/CT and elevated β2 microglobulin are negative predictors of outcome in high tumor burden follicular lymphoma treated by immunochemotherapy: a pooled analysis of three prospective studies
.
Blood
.
2016
;
128
(
22
):
1101
.
57.
Mondello
P
,
Strati
P
,
Merryman
RW
, et al.
R-CHOP versus R-bendamustine with or without rituximab maintenance in newly diagnosed follicular lymphoma patients with high SUV at baseline PET
.
Blood
.
2020
;
136
(
suppl 1
):
39
-
40
.
58.
Cottereau
AS
,
Rebaud
L
,
Trotman
J
, et al.
Metabolic tumor volume predicts outcome in patients with advanced stage follicular lymphoma from the RELEVANCE trial
.
Ann Oncol
.
2024
;
35
(
1
):
130
-
137
.
59.
Trotman
J
,
Luminari
S
,
Boussetta
S
, et al.
Prognostic value of PET-CT after first-line therapy in patients with follicular lymphoma: a pooled analysis of central scan review in three multicentre studies
.
Lancet Haematol
.
2014
;
1
(
1
):
e17
-
e27
.
60.
Nath
K
,
Law
SC
,
Sabdia
MB
, et al.
Intratumoral T cells have a differential impact on FDG-PET parameters in follicular lymphoma
.
Blood Adv
.
2021
;
5
(
12
):
2644
-
2649
.
61.
Meignan
M
,
Cottereau
AS
,
Versari
A
, et al.
Baseline metabolic tumor volume predicts outcome in high-tumor-burden follicular lymphoma: a pooled analysis of three multicenter studies
.
J Clin Oncol
.
2016
;
34
(
30
):
3618
-
3626
.
62.
Jemaa
S
,
Fredrickson
J
,
Coimbra
A
, et al.
A fully automated measurement of total metabolic tumor burden in diffuse large B-cell lymphoma and follicular lymphoma
.
Blood
.
2019
;
134
(
suppl 1
):
4666
.
63.
Claudel
A
,
Cottereau
AS
,
Bachy
E
, et al.
Combining PET/CT and Ctdna assessments at 6 months from induction treatment better predicts outcome in previously untreated patients with follicular lymphoma: a relevance ancillary Lysa study
.
Blood
.
2023
;
142
(
suppl 1
):
170
.
64.
Ferrero
S
,
Assanto
GM
,
Durmo
R
, et al.
Combined use of minimal residual disease monitoring and FDG-PET for outcome prediction in follicular lymphoma: results from the fondazione italiana linfomi (FIL) FOLL12 trial
.
Hematol Oncol
.
2023
;
41
(
S2
):
183
-
185
.
65.
Link
BK
,
Maurer
MJ
,
Nowakowski
GS
, et al.
Rates and outcomes of follicular lymphoma transformation in the immunochemotherapy era: a report from the university of Iowa/Mayo Clinic specialized program of research excellence molecular epidemiology resource
.
J Clin Oncol
.
2013
;
31
(
26
):
3272
-
3278
.
66.
Day
JR
,
Larson
MC
,
Casulo
C
, et al.
Patterns of care and prognostic modeling following follicular lymphoma transformation to aggressive B-cell lymphoma: an analysis from the LEO consortium
.
Blood
.
2023
;
142
(
suppl 1
):
3111
.
67.
Muntañola
A
,
Mozas
P
,
Mercadal
S
, et al.
Early progression in follicular lymphoma in the absence of histological transformation or high-risk follicular lymphoma international prognostic index still has a favourable outcome
.
Br J Haematol
.
2023
;
200
(
3
):
306
-
314
.
68.
Luttwak
E
,
Qiu
A
,
Okwali
M
, et al.
Impact of early histological transformation on survival in patients with follicular lymphoma
.
Blood
.
2023
;
142
(
suppl 1
):
3023
.
69.
Batlevi
CL
,
Sha
F
,
Alperovich
A
, et al.
Positron-emission tomography–based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma
.
Eur J Cancer
.
2020
;
126
:
78
-
90
.
70.
Lossos
IS
,
Alizadeh
AA
,
Diehn
M
, et al.
Transformation of follicular lymphoma to diffuse large-cell lymphoma: alternative patterns with increased or decreased expression of c-MYC and its regulated genes
.
Proc Natl Acad Sci U S A
.
2002
;
99
(
13
):
8886
-
8891
.
71.
Lo Coco
F
,
Gaidano
G
,
Louie
DC
, et al.
p53 mutations are associated with histologic transformation of follicular lymphoma
.
Blood
.
1993
;
82
(
8
):
2289
-
2295
.
72.
Kridel
R
,
Chan
FC
,
Mottok
A
, et al.
Histological transformation and progression in follicular lymphoma: a clonal evolution study
.
PLoS Med
.
2016
;
13
(
12
):
e1002197
.
73.
Jacobson
CA
,
Chavez
JC
,
Sehgal
AR
, et al.
Axicabtagene ciloleucel in relapsed or refractory indolent non-Hodgkin lymphoma (ZUMA-5): a single- arm, multicentre, phase 2 trial
.
Lancet Oncol
.
2022
;
23
(
1
):
91
-
103
.
74.
Budde
LE
,
Sehn
LH
,
Matasar
M
, et al.
Safety and efficacy of mosunetuzumab, a bispecific antibody, in patients with relapsed or refractory follicular lymphoma: a single-arm, multicentre, phase 2 study
.
Lancet Oncol
.
2022
;
23
(
8
):
1055
-
1065
.
75.
Leonard
JP
,
Trneny
M
,
Izutsu
K
, et al.
AUGMENT: a phase III study of lenalidomide plus rituximab versus placebo plus rituximab in relapsed or refractory indolent lymphoma
.
J Clin Oncol
.
2019
;
37
(
14
):
1188
-
1199
.
76.
Zinzani
PL
,
Mayer
J
,
Flowers
CR
, et al.
ROSEWOOD: a phase II randomized study of zanubrutinib plus obinutuzumab versus obinutuzumab monotherapy in patients with relapsed or refractory follicular lymphoma
.
J Clin Oncol
.
2023
;
41
(
33
):
5107
-
5117
.
77.
Lansigan
F
,
Andorsky
DJ
,
Coleman
M
, et al.
P1156: magnify phase 3b study of lenalidomide + rituximab (R2) followed by maintenance in relapsed/refractory indolent non-hodgkin lymphoma: complete induction phase analysis
.
Hemasphere
.
2022
;
6
(
suppl
):
1043
-
1044
.
78.
Alderuccio
JP
,
Alencar
AJ
,
Schatz
JH
, et al.
Limited duration loncastuximab tesirine with rituximab induces high complete metabolic response rate in high-risk relapsed/refractory follicular lymphoma—a phase 2 study
.
Blood
.
2023
;
142
(
suppl 1
):
984
.
You do not currently have access to this content.