Abstract

The treatment landscape for chronic lymphocytic leukemia (CLL) has been transformed by the advent of covalent Bruton tyrosine kinase (BTK) inhibitors (cBTKis) and B-cell lymphoma 2 (BCL-2) inhibitors, leading to markedly improved outcomes and, for many, near-normal life expectancy. However, patients progressing after both classes of therapy (double-refractory) have limited options and poor prognoses. This review outlines a practical approach to managing double-exposed or double-refractory CLL, incorporating clinical cases, trial data, and expert perspectives. For cBTKi intolerance, second-generation agents may remain effective. Venetoclax retreatment is reasonable after prior fixed-duration use. In true double-refractory disease, noncovalent BTK inhibitors (eg, pirtobrutinib) and CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy (lisocabtagene maraleucel) are standard-of-care options. Pirtobrutinib induces rapid responses, though often of limited duration, underscoring the need for early consolidation planning with CAR-T or allogeneic stem cell transplant. Persistent disease after CAR-T therapy warrants close monitoring and timely transplant referral in eligible patients. Phosphoinositide 3-kinase inhibitors remain available but are limited by toxicity and modest benefit. Emerging agents, including BTK degraders, bispecific antibodies, and novel cellular therapies, offer promising future directions. Optimizing outcomes in double-refractory CLL requires an individualized, nuanced strategy integrating available treatments with innovative approaches under investigation.

1.
Hallek
M
.
Chronic lymphocytic leukemia: 2025 update on the epidemiology, pathogenesis, diagnosis, and therapy
.
Am J Hematol
.
2025
;
100
(
3
):
450
-
480
.
2.
Mato
AR
,
Hess
LM
,
Chen
Y
, et al
.
Outcomes for patients with chronic lymphocytic leukemia (CLL) previously treated with both a covalent BTK and BCL2 inhibitor in the United States: a real-world database study
.
Clin Lymphoma Myeloma Leuk
.
2023
;
23
(
1
):
57
-
67
.
3.
Shadman
M
.
Diagnosis and treatment of chronic lymphocytic leukemia: a review
.
JAMA
.
2023
;
329
(
11
):
918
-
932
.
4.
Lew
TE
,
Lin
VS
,
Cliff
ER
, et al
.
Outcomes of patients with CLL sequentially resistant to both BCL2 and BTK inhibition
.
Blood Adv
.
2021
;
5
(
20
):
4054
-
4058
.
5.
Yoon
JT
,
Zhou
Y
,
Mikhaleva
M
, et al
.
Characteristics and outcomes of patients with double refractory and double exposed chronic lymphocytic leukemia
.
Blood Adv
.
2025
;
9
(
11
):
2808
-
2817
.
6.
Samples
L
,
Ujjani
CS
,
Khajaviyan
S
, et al
.
Clinical outcomes in patients treated with both covalent Btkis and venetoclax and the significance of “double-refractory” status in patients with CLL/SLL [abstract]
.
Blood
.
2023
;
142
(
suppl 1
):
4650
.
7.
Bonfiglio
S
,
Sutton
LA
,
Ljungström
V
, et al
.
BTK and PLCG2 remain unmutated in one third of patients with CLL relapsing on ibrutinib
.
Blood Adv
.
2023
;
7
(
12
):
2794
-
2806
.
8.
Tam
CS
,
Balendran
S
,
Blombery
P
.
Novel mechanisms of resistance in CLL: variant BTK mutations in second-generation and noncovalent BTK inhibitors
.
Blood
.
2025
;
145
(
10
):
1005
-
1009
.
9.
Sullivan
GP
,
Flanagan
L
,
Rodrigues
DA
,
Ní Chonghaile
T
.
The path to venetoclax resistance is paved with mutations, metabolism, and more
.
Sci Transl Med
.
2022
;
14
(
674
):
eabo6891
.
10.
Mato
AR
,
Woyach
JA
,
Brown
JR
, et al
.
Pirtobrutinib after a covalent BTK inhibitor in chronic lymphocytic leukemia
.
N Engl J Med
.
2023
;
389
(
1
):
33
-
44
.
11.
Siddiqi
T
,
Maloney
DG
,
Kenderian
SS
, et al
.
Lisocabtagene maraleucel in chronic lymphocytic leukaemia and small lymphocytic lymphoma (TRANSCEND CLL 004): a multicentre, open-label, single-arm, phase 1-2 study
.
Lancet
.
2023
;
402
(
10402
):
641
-
654
.
12.
Thompson
MC
,
Bhat
SA
,
Jurczak
W
, et al
.
Outcomes of therapies following discontinuation of non-covalent Bruton’s tyrosine kinase inhibitors for patients with chronic lymphocytic leukemia and Richter transformation: results from an international, multicenter study [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
1870
.
13.
Shadman
M
,
Maloney
DG
.
Immune therapy for chronic lymphocytic leukemia: allogeneic transplant, chimeric antigen receptor T-cell therapy, and beyond
.
Hematol Oncol Clin North Am
.
2021
;
35
(
4
):
847
-
862
.
14.
Shadman
M
,
Salkar
M
,
Srivastava
B
, et al
.
Real-world outcomes following ibrutinib dose reduction in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma
.
Leuk Lymphoma
.
2025
;
66
(
1
):
44
-
53
.
15.
Awan
FT
,
Schuh
A
,
Brown
JR
, et al
.
Acalabrutinib monotherapy in patients with chronic lymphocytic leukemia who are intolerant to ibrutinib
.
Blood Adv
.
2019
;
3
(
9
):
1553
-
1562
.
16.
Rogers
KA
,
Thompson
PA
,
Allan
JN
, et al
.
Phase II study of acalabrutinib in ibrutinib-intolerant patients with relapsed/refractory chronic lymphocytic leukemia
.
Haematologica
.
2021
;
106
(
9
):
2364
-
2373
.
17.
Shadman
M
,
Flinn
IW
,
Levy
MY
, et al
.
Phase 2 study of zanubrutinib in BTK inhibitor-intolerant patients (Pts) with relapsed/refractory B-cell malignancies [abstract]
.
Blood
.
2021
;
138
(
suppl 1
):
1410
.
18.
Shadman
M
,
Burke
JM
,
Cultrera
J
, et al
.
Zanubrutinib is well tolerated and effective in CLL/SLL patients intolerant of ibrutinib/acalabrutinib: updated results
.
Blood Adv
.
2025
;
9
(
16
):
4100
-
4110
.
19.
Shah
NN
,
Wang
M
,
Roeker
LE
, et al
.
Pirtobrutinib monotherapy in Bruton tyrosine kinase inhibitor-intolerant patients with B-cell malignancies: results of the phase I/II BRUIN trial
.
Haematologica
.
2025
;
110
(
1
):
92
-
102
.
20.
Thompson
MC
,
Harrup
RA
,
Coombs
CC
, et al
.
Venetoclax retreatment of patients with chronic lymphocytic leukemia after a previous venetoclax-based regimen
.
Blood Adv
.
2022
;
6
(
15
):
4553
-
4557
.
21.
Davids
MS
,
Fischer
K
,
Robrecht
S
, et al
.
ReVenG: a phase 2 study of venetoclax plus obinutuzumab retreatment in patients with relapsed chronic lymphocytic leukemia [abstract]
.
Blood
.
2021
;
138
(
suppl 1
):
2634
.
22.
Kater
AP
,
Harrup
RA
,
Kipps
TJ
, et al
.
The MURANO study: final analysis and retreatment/crossover substudy results of VenR for patients with relapsed/refractory CLL
.
Blood
.
2025
;
145
(
23
):
2733
-
2745
.
23.
Davids
MRS
,
Tausch
E
,
Stilgenbauer
S
, et al
. Preliminary results of the ongoing multicenter, phase 2 study of retreatment with venetoclax plus obinutuzumab (reveng) in patients with recurrent chronic lymphocytic leukemia (CLL). Paper presented at: European Hematology Association.
12 to 15 June 2025
. Milan, Italy.
24.
Hampel
PJ
,
Ding
W
,
Call
TG
, et al
.
Rapid disease progression following discontinuation of ibrutinib in patients with chronic lymphocytic leukemia treated in routine clinical practice
.
Leuk Lymphoma
.
2019
;
60
(
11
):
2712
-
2719
.
25.
Woyach
JA
.
Mechanisms of resistance to BTK inhibitors in patients with chronic lymphocytic leukemia
.
Clin Adv Hematol Oncol
.
2021
;
19
(
7
):
436
-
438
.
26.
Woyach
JA
,
Jones
D
,
Jurczak
W
, et al
.
Mutational profile in previously treated patients with chronic lymphocytic leukemia progression on acalabrutinib or ibrutinib
.
Blood
.
2024
;
144
(
10
):
1061
-
1068
.
27.
Brown
JR
,
Li
J
,
Eichhorst
B
, et al
.
Acquired mutations in patients with relapsed/refractory CLL who progressed in the alpine study
.
Blood Adv
.
2025
;
9
(
8
):
1918
-
1926
.
28.
Davids
MS
,
Shadman
M
,
Parikh
SA
, et al
.
A multicenter, retrospective study of accelerated venetoclax ramp-up in patients with relapsed/refractory chronic lymphocytic leukemia
.
Am J Hematol
.
2022
;
97
(
3
):
E105
-
E109
.
29.
Koenig
K
,
Dotson
E
,
Sheredy
S
, et al
.
Rapid dose escalation of venetoclax in patients with relapsed/refractory chronic lymphocytic leukemia previously treated with B-cell receptor inhibitor therapy [abstract]
.
Blood
.
2019
;
134
(
suppl 1
):
3045
.
30.
Jones
JA
,
Mato
AR
,
Wierda
WG
, et al
.
Venetoclax for chronic lymphocytic leukaemia progressing after ibrutinib: an interim analysis of a multicentre, open-label, phase 2 trial
.
Lancet Oncol
.
2018
;
19
(
1
):
65
-
75
.
31.
Crombie
JL
,
Ahn
IE
,
Tyekucheva
S
, et al
.
SAVE (Safe Accelerated Venetoclax Escalation): initial results of a prospective, phase Ib study of venetoclax with an accelerated dose ramp-up in patients with CLL [abstract]
.
J Clin Oncol
.
2023
;
41
(
suppl 16
):
7512
.
32.
Soumerai
JD
,
Barrientos
J
,
Ahn
I
, et al
.
Consensus recommendations from the 2024 Lymphoma Research Foundation workshop on treatment selection and sequencing in CLL or SLL
.
Blood Adv
.
2025
;
9
(
5
):
1213
-
1229
.
33.
Sharman
JP
,
Munir
T
,
Grosicki
S
, et al
.
BRUIN CLL-321: randomized phase III trial of pirtobrutinib versus idelalisib plus rituximab (IdelaR) or bendamustine plus rituximab (BR) in BTK inhibitor pretreated chronic lymphocytic leukemia/small lymphocytic lymphoma [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
886
.
34.
Woyach
JA
,
Brown
JR
,
Ghia
P
, et al
.
Pirtobrutinib in post-cBTKi CLL/SLL: ∼30 months follow-up and subgroup analysis with/without prior BCL2i from the phase 1/2 BRUIN study [abstract]
.
Blood
.
2023
;
142
(
suppl 1
):
325
.
35.
Wang
E
,
Mi
X
,
Thompson
MC
, et al
.
Mechanisms of resistance to noncovalent Bruton’s tyrosine kinase inhibitors
.
N Engl J Med
.
2022
;
386
(
8
):
735
-
743
.
36.
Brown
JR
,
Desikan
SP
,
Nguyen
B
, et al
.
Genomic evolution and resistance during pirtobrutinib therapy in covalent BTK-inhibitor (cBTKi) pre-treated chronic lymphocytic leukemia patients: updated analysis from the BRUIN study [abstract]
.
Blood
.
2023
;
142
(
suppl 1
):
326
.
37.
Wierda
WGMD
,
Kenderian
SS
,
Brander
DM
, et al
.
Characteristics associated with response to lisocabtagene maraleucel (liso-cel) in patients (pts) with R/R CLL/SLL: exploratory analyses from TRANSCEND CLL 004 [abstract]
.
HemaSphere
.
2024
;
8
(
suppl 1
):
126
-
127
.
38.
Wierda
WG
,
Dorritie
K
,
Gauthier
J
, et al
.
Lisocabtagene maraleucel (liso-cel) combined with ibrutinib (ibr) for patients (pts) with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL): primary results from the open-label, phase 1/2 transcend CLL 004 study [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
887
.
39.
Miklos
DB
,
Riedell
PA
,
Bokun
A
,
Chavez
JC
,
Schuster
SJ
.
Leveraging the immunomodulatory potential of ibrutinib for improved outcomes of T cell-mediated therapies of B cell malignancies: a narrative review
.
Target Oncol
.
2025
;
20
(
2
):
217
-
234
.
40.
Sharman
JP
,
Coutre
SE
,
Furman
RR
, et al
.
Final results of a randomized, phase III study of rituximab with or without idelalisib followed by open-label idelalisib in patients with relapsed chronic lymphocytic leukemia
.
J Clin Oncol
.
2019
;
37
(
16
):
1391
-
1402
.
41.
Flinn
IW
,
Hillmen
P
,
Montillo
M
, et al
.
The phase 3 DUO trial: duvelisib vs ofatumumab in relapsed and refractory CLL/SLL
.
Blood
.
2018
;
132
(
23
):
2446
-
2455
.
42.
Coutré
SE
,
Barrientos
JC
,
Brown
JR
, et al
.
Management of adverse events associated with idelalisib treatment: expert panel opinion
.
Leuk Lymphoma
.
2015
;
56
(
10
):
2779
-
2786
.
43.
Roeker
LE
,
Woyach
JA
,
Cheah
CY
, et al
.
Fixed-duration pirtobrutinib plus venetoclax with or without rituximab in relapsed/refractory CLL: the phase 1b BRUIN trial
.
Blood
.
2024
;
144
(
13
):
1374
-
1386
.
44.
Gauthier
J
,
Hirayama
AV
,
Hay
KA
, et al
.
Comparison of efficacy and toxicity of CD19-specific chimeric antigen receptor T-cells alone or in combination with ibrutinib for relapsed and/or refractory CLL [abstract]
.
Blood
.
2018
;
132
(
suppl 1
):
299
.
45.
Gill
S
,
Vides
V
,
Frey
NV
, et al
.
Anti-CD19 CAR T cells in combination with ibrutinib for the treatment of chronic lymphocytic leukemia
.
Blood Adv
.
2022
;
6
(
21
):
5774
-
5785
.
46.
Jain
N
,
Keating
M
,
Thompson
P
, et al
.
Ibrutinib plus venetoclax for first-line treatment of chronic lymphocytic leukemia: a nonrandomized phase 2 trial
.
JAMA Oncol
.
2021
;
7
(
8
):
1213
-
1219
.
47.
Siddiqi
T
,
Maloney
DG
,
Kenderian
SS
, et al
.
Lisocabtagene maraleucel (liso-cel) in R/R CLL/SLL: 24-month median follow-up of TRANSCEND CLL 004 [abstract]
.
Blood
.
2023
;
142
(
suppl 1
):
330
.
48.
Kim
HT
,
Hu
Z-H
,
Woo Ahn
K
, et al
.
Prognostic score and cytogenetic risk classification for chronic lymphocyteic leukemia patients who underwent reduced intensity conditioning allogeneit HCT: a CIBMTR report [abstract]
.
Blood
.
2017
;
130
(
suppl 1
):
667
.
49.
Roeker
LE
,
Dreger
P
,
Brown
JR
, et al
.
Allogeneic stem cell transplantation for chronic lymphocytic leukemia in the era of novel agents
.
Blood Adv
.
2020
;
4
(
16
):
3977
-
3989
.
50.
Kim
HT
,
Shaughnessy
CJ
,
Rai
SC
, et al
.
Allogeneic hematopoietic cell transplantation after prior targeted therapy for high-risk chronic lymphocytic leukemia
.
Blood Adv
.
2020
;
4
(
17
):
4113
-
4123
.
51.
Shadman
M
,
Fakhri
B
,
Jain
N
.
Consensus in CLL: global needs matter
.
Blood Adv
.
2025
;
9
(
5
):
1210
-
1212
.
52.
Shah
NN
,
Omer
Z
,
Collins
GP
, et al
.
Efficacy and safety of the Bruton’s tyrosine kinase (BTK) degrader NX-5948 in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL): updated results from an ongoing phase 1a/b study [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
884
.
53.
Thompson
MC
,
Parrondo
RD
,
Frustaci
AM
, et al
.
Preliminary efficacy and safety of the Bruton tyrosine kinase degrader BGB-16673 in patients with relapsed or refractory chronic lymphocytic leukemia/small lymphocytic lymphoma: results from the phase 1 CaDAnCe-101 study [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
885
.
54.
Danilov
A
,
Fakhri
B
,
Awan
FT
, et al
.
Epcoritamab monotherapy in patients (Pts) with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL): results from CLL expansion and optimization cohorts of Epcore CLL-1 [abstract]
.
Blood
.
2024
;
144
(
suppl 1
):
883
.
You do not currently have access to this content.
Sign in via your Institution