Download ESMO E-learning: PARP Inhibition - basic science

PARP inhibition – basic
science and clinical challenge
Thomas Helleday, PhD
Poly (ADP-ribose) Polymerase 1 (PARP1)
Reprinted by permission from Macmillan Publishers Ltd: Rouleau M et al. Nat Rev Cancer 2010;10:293-301 copyright (2010)
PARP family of proteins
DNA repair
Reprinted by permission from Macmillan Publishers Ltd: Schreiber J et al. Nat Rev Mol Cell Biol 2006;7:517-528 copyright (2006)
DNA damage/NAD+ levels dictate responses
Ström CE and Helleday T. Biomolecules 2012;2:635-649 by permission of CCPL (2012)
PARP1 is critical for efficient SSB repair
DNA single-strand break
PARP1
XRCC1 – Ligase3
PNKP, APTX
PNKP
Polβ
APTX
Lig3
XRCC1
PCNA , Polδ/ε , Polβ,
Ligase1, FEN1
PCNA
Polδ/ε
Polβ
Lig3
XRCC1
short patch
Lig3
XRCC1
FEN1
Lig3
XRCC1 Lig1
Polβ
long patch
PCNA
Lig1
Ström CE et al. Nucleic Acids Res 2011;39:3166-3175 by permission of Oxford University Press
BRCA2 deficient cells are killed by
PARP inhibitors
g
V-C8
gH2Ax + DNA
gH2Ax
V-C8+B2
BRCA2 defective
HR
Reprinted by permission from Macmillan Publishers Ltd: Bryant HE et al. Nature 2005;434(7035):913-917 copyright (2005);
Farmer H et al. Nature 2005;434(7035):917-920
Specific killing of BRCA2 deficient
tumours with PARP inhibitors
AG14361 25 mg/kg
Relative thigh circumference
2.2
2.0
V-C8+B2 control
V-C8+B2 AG14361
V-C8 control
V-C8 AG14361
1.8
1.6
1.4
1.2
1.0
0.8
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Days post implant
Reprinted by permission from Macmillan Publishers Ltd: Bryant HE et al. Nature 2005;434(7035):913-917 copyright (2005)
Synthetic lethality as an approach for
anti-cancer treatments
Cancer cells
PARP
Inhibition
Normal cells
PARP
Inhibition
SSB repair
Homologous
Recombination
BRCA2-/-
Cell
death
Survival
Helleday T.
SSB repair
Homologous
Recombination
BRCA2+/-
Survival
Survival
PARP inhibitors
in monotherapy
PARP inhibitors in treatment for
BRCA1/2 cancer
>80 clinical trials with PARP inhibitors in phase I-II
Treatment duration
(week)
Progressive disease
Stable disease
Partial response
Complete response
Ovarian cancer
Prostate cancer
Breast cancer
80
60
40
20
0
From Fong PC et al. New Engl J Med 2009;361(2):123-134. Copyright © (2009) Massachusetts Medical Society.
Reprinted with permission from Massachusetts Medical Society
PARP inhibitors in treatment for
BRCA1/2 ovarian cancer
Olaparib 400 mg twice daily
Olaparib 100 mg twice daily
Reprinted from Audeh MW et al. Lancet 2010;376(9737):245-251. Copyright (2010), with permission from Elsevier
Response to PARP inhibitors in triple
negative breast cancer is dictated by
BRCA mutation
Olaparib 400 mg twice daily
Reprinted from Gelmon KA et al. Lancet Oncol 2011;12(9):852-861. Copyright (2011), with permission from Elsevier
Platinum resistant ovarian cancers and
non-BRCA respond to PARP inhibitor
Reprinted from Gelmon KA et al. Lancet Oncol 2011;12(9):852-861. Copyright (2011), with permission from Elsevier
Olaparib maintenance treatment improve
progression-free survival in relapsed
high-grade serous ovarian cancer
Probability of
progression-free survival
1.0
0.8
Olaparib
0.6
0.4
0.2
Placebo
Hazard ratio, 0.35 (95% CI, 0.25-0.49)
P<0.001
0.0
0
3
6
9
12
Months since randomization
Adapted from Ledermann J et al. N Engl J Med 2012;366(15):1382-1392
15
Ovarian cancers often have silenced
Fanconi anemia (FA) pathway, rendering
in homologous recombination defect
PARP-sensitive tumour
PARP-resistant tumour?
Reprinted by permission from Macmillan Publishers Ltd: Taniguchi T et al. Nat Med 2003;9(5):568-574 copyright (2003)
Biomarkers for PARP inhibitor sensitivity
in monotherapy?
BRCA1/2 mutation
Silenced or mutated BRCA related genes
PARP1 protein levels or PARP activity
Functional homologous recombination assay (RAD51 foci, FA
status)
RNA/DNA signatures correlating with BRCA status
BRCA mutational signature
Resistance to PARP inhibitors
Cancer cells
PARP inhibitor BRCA2 mutation
Resistant
clone
Cell
Death
Survival
Rottenberg S et al. Proc Natl Acad Sci U S A 2008;105(44):17079-17084;
Reprinted by permission from Macmillan Publishers Ltd: Sakai W et al. Nature 2008;451:1116-1120 copyright (2003)
Complicity of genetic networks – 53BP1
loss as resistance mechanism
Ancestrial suppressed network
53BP1
BRCA
PARPi
Reprinted from Bunting SF et al. Cell 2010;141:243-254. Copyright (2010), with permission from Elsevier
PARP inhibitors in
combination therapy
Iniparib plus chemotherapy in metastatic
triple-negative breast cancer
Overall survival (%)
100
Hazard ratio for death with iniparib,
0.57 (95% CI, 0.36-0.90)
P=0.01
80
60
Gemcitabine-carboplatin
plus iniparib
40
Gemcitabine-carboplatin
alone
20
0
0
2
4
6
8
10
12
14
Months
Adapted from O'Shaughnessy J et al. N Engl J Med 2011;364(3):205-214
16
18
20
22
24
Iniparib plus chemotherapy in metastatic
triple-negative breast cancer
Reasons for phase III to fail?
Phase II design (open label)
Combination with gem-carbo?
No selection for BRCA mutated
patients?
Iniparib is not a PARP inhibitor
O'Shaughnessy J et al. N Engl J Med 2011;364(3):205-214;
Reprinted from Patel AG et al. Clin Cancer Res 2012;18:1655-1662, with permission from AACR
Kaplan Meier Plot
with number of subjects at risk
Survival probability
1.0
+ Censored
95% Confidence limits
0.8
0.6
0.4
0.2
0.0
46
39
34
30
25
23
18
13
7
7
0
2
4
6
8
10
12
14
16
18
Overall survival (months)
Best % tumour shrinkage from baseline
Rucaparib (PF-01367338, AG014699),
with temozolomide in patients with
metastatic melanoma
60.00
40.00
20.00
0.00
-20.00
-40.00
-60.00
-80.00
-100.00
Patient
Conclusion: This study show that temozolomide
(150–200 mg/m2/day) can safely be given with a PARP inhibitory
dose of rucaparib, increasing progression-free survival over
historical controls in metastatic melanoma patients
Redrawn from Plummer R et al. Cancer Chemother Pharmacol 2013;71(5):1191-1199
Strategies using PARP
inhibitors as anti-cancer
agents - overview
Potentiating
chemotherapy
a normal
no DNA damage
b normal
BRCAmut
PARP inhibitors
selectively toxic to
BRCAmut cancer
c normal
replication
stress
PARP inhibitors with
some toxicity to DNA
damaged cancer cells
d replication
stress
+chemo
PARP
active
PARP inhibitors
sensitise all cells to
chemotherapy no
clinical benefit
e replication
stress
+chemo
not PARP
activate
PARP inhibitors +
chemotherapy work
with additive effect,
potential clinical
benefit
f DNA damage
stress
+CDK1
inhibitor
Targeted inhibitors
activate PARP in
cancer, PARP
inhibitors have clinical
benefit
g DNA damage
stress
hypoxia
hypoxia activates
PARP in cancer,
PARP inhibitors may
have clinical benefit
Synthetic lethality
Combined with
targeted therapies
Enhance cancerspecific DNA damage
Context specific
synthetic lethality
Low PAR
Helleday T. Curr Opin Oncol 2013;25:609-614
PARP activity stained by PAR polymers
High PAR
PARP inhibitors
have no clinical
benefit
Receptor negative cancer, p53 mutated and
Fanconi’s anemia (FA) silenced
Platinum resistant
by DNA-PK loss
RESIDUAL TUMOUR
PRIMARY TUMOUR
What combination will work in the clinic
depends on tumour characteristics and
drug mechanism of action
Therapy
DNA repair inhibitor
-
PARP inhibitor
+
Platinum-based
chemo
PARP inhibitor
++
FA silenced cells are sensitive to both platinum-based chemo
and PARP inhibitors, which cause different DNA lesions, additive
effect with both treatments, some normal tissue toxicity.
Platinum-based
chemo
Proteasome inhibitor
--
Proteasome inhibitors inhibit FA-mediated crosslink repair.
Preferential induction of normal tissue toxicity.
Platinum-based
chemo
DNA-PK inhibitor
---
Sensitivity to crosslinking agents in FA-silenced cells depend
on active DNA-PK activity. Cancer cells become selectively
resistant to platinum-based chemo.
Platinum-based
chemo
Non-FA crosslink inhibitor
+++
FA silenced cells rely on non-FA mediated repair for survival,
which normal cells do not. This pathway not yet identified.
Temozolomide
PARP inhibitor
-
Temozolomide not standard in ovarian cancer, PARP activity
required for normal cell survival. Risk of potentiating side effects.
Radiotherapy
ATR/Chk1 inhibtor
+
ATR/Chk1 inhibitors sensitises to radiotherapy and are especially
active in p53 mutated cancer. Furthermore, FA silenced cells
exhibit replication lesions requiring ATR/Chk1 for survival
Doxorubicin
PARP inhibitor
+++
DNA-PK lost cells rely on PARP-mediated backup-end joining
repair of doxorubicin-induced double-strand breaks. Normal cells
have DNA-PK and are not sensitised by PARP inhibitors
Paclitaxel
-
Paclitaxel
Chk1 inhibitor
Value
+
++
Comment
FA silenced cells exhibit decreased homologous
recombination and sensitivity to PARP inhibitors
Mitosis inhibitor causing uncapping at telomers and DNA
damage signalling-mediated cell death.
Docetaxel triggers Chk1-mediated mitotic checkpoint required
for survival in p53 mutated cells
PARP inhibitor mechanism
of action
PARP is involved in SSBR, replication repair,
alt-NHEJ, fork protection, NER and BER
Ström CE and Helleday T. Biomolecules 2012;2:635-649
PARP1 trapping is required for PARP
inhibitor toxicity
Reprinted from Murai J et al. Cancer Res 2012;72(21):5588-5599, with permission from AACR
PARP1 + BRCA2 protects replication
forks from Mre11 degradation
Reprinted from Ying S et al. Cancer Res 2012;72(11):2814-2821, with permission from AACR
PARP1 + BRCA2 protects replication
forks from Mre11 degradation
PARP inhibitors
HR
BER
RR
Prot
Trap
alt
NHEJ
PARP inhibitors inhibits several PARP family member
Reprinted from Ying S et al. Cancer Res 2012;72(11):2814-2821, with permission from AACR
SUMMARY
Efficacy of PARP inhibitors in monotherapy coupled with HR defect
Combination strategy complex and in depth mechanistic
understanding needed
PARP inhibitors trap PARP on DNA and has different effect from
protein loss
PARP1 is involved in SSB repair, replication restart, fork protection,
B-NHEJ
Resistance can develop to PARP inhibitors
Thank you!