Transcript DNA Repair BEA Template - Q-CROC

PARP Inhibition: A New Approach
To Cancer Therapy?
Dr. Geert Kolvenbag
Date
1
Potential Conflict of Interest
• Employee and Shareholder / 1988 – AstraZeneca
Date
2
PARP Inhibition:
A New Therapeutic Approach?
Geert J.C.M. Kolvenbag MD PhD
Global Product Vice President
AstraZeneca
Targeting DNA Repair in Oncology
DNA damage occurs all the time in all cells
Why is DNA
repair a good
target?
DNA repair defects lead to increased
cancer susceptibility and increased
sensitivity to DNA damaging agents
Normal cells have multiple DNA repair
pathways but some are lost in cancer cells
Inhibiting DNA repair in cancer cells that have
impaired repair pathways leads to selective
cell killing and an increased therapeutic ratio
Inducing Synthetic Lethality in Cancer Cells
Normal Cell
Pre-cancerous Cell
Full complement
of repair pathways
DNA damage leads
to continuous
activation of
pathway A
AB
AB
Cancer Cell
Alternative DNA
repair pathways
available
B
AB
Pathway B inhibitor
Selective pressure
loss of pathway A,
genetic instability,
reliance on pathway B
Death
Survival
AB
B
Cancer Cells are Highly Susceptible
to DNA Repair Inhibition

Cancer cells

Undergo deregulated proliferation
 less time for DNA repair than in normal cells

Grow under stress, which causes ongoing DNA
damage

Have DNA repair defects
 mutator phenotype
 allow growth despite ongoing genome instability

Are reliant on the DNA repair pathways they
still retain
Focus on DDR Pathways for SSBs/DSBs
Type of
damage:
Singlestrand
breaks
(SSBs)
Doublestrand
breaks
(DSBs)
Bulky
adducts
O6alkylguanine
Insertions
& deletions
Mismatch
repair
Repair
pathway:
Base
excision
repair
Repair
enzymes:
PARP
Recombinational
repair
HR
NHEJ
ATM
BRCA
DNA-PK
Nucleotideexcision
repair
XP,
MSH2,
poly- MLH1
merases
Direct
reversal
AGT
Mechanisms of Action of Olaparib
PARP olaparib
SSBs increased by dacarbazine,
temozolomide and topotecan
Replicating cells
Mechanism 2:
Potentiation
DSBs increased by platinums
Normal cell
Repair by
Homologous
Recombination
Survival
Cancer cell with HRD
Mechanism 1:
Tumor specific
killing by olaparib
No effective repair
(No HR pathway)
Cell death
Hypothesis
 In situations where the DNA repair is compromised
inhibition of PARP will lead to synthetic lethality of the cell
 DNA repair factors deficient in functioning:
 BRCA gene deficient in genotype or phenotype
 Other Homologues Recombination Repair factors deficient in
functioning (HRD) , eg ATM, MDC1, MRE11
 In presence of DNA damaging agents
 Chemotherapy
 Radiotherapy
Olaparib: An oral inhibitor of
Poly (ADP-ribose) Polymerase (PARP)
IC50 on PARP-1 = 4.9 nM
IC50 on PARP-2 ≈ 5nM
IC50 on PARP-3 ≈ 50nM
IC50 on Tankyrase >1M
O
N
N
O
N
F
N
O
• olaparib (AZD2281; KU-0059436)
• Favorable PK
• Good bioavailability across species
• Tumor PK -Significant levels at 24 hrs following single oral dose
 Does the PARP inhibition result in therapeutic effects
 In vitro
 In vivo
 Clinical response
Increased Sensitivity of BRCA1-/- and
BRCA2-/- Cells to PARP Inhibition
BRCA2+/+
BRCA1+/+
BRCA2+/-
BRCA1+/BRCA1-/-
BRCA2-/-
No difference in sensitivity between
heterozygous and wild-type BRCA cells
Targeted inhibition  selective and less toxic therapy
Farmer et al. Nature 2005; 434:917-21
BRCA 1 & 2 -/- ES Cells are Very
Sensitive to PARP Inhibition
-1
-2
Wild type
BRCA2 +/BRCA2 -/-
-3
-4
0
10-9 10-8 10-7 10-6 10-5 10-4
PARP inhibitor concentration (M)
Mean number of chromatid
aberrations per cell
0
Log
surviving
fraction
Increased levels of chromosomal
aberrations in PARP inhibitor
treated BRCA2 -/- cells
4
3
Complex
aberrations
2
Chromatid
breaks
1
0
WT
WT
BRCA-/- BRCA2-/+ PARPi
+ PARPi
Farmer et al. Nature 2005; 434:917-21
KU95 Cell Line Panel: Olaparib Sensitivity
Olaparib IC50 data by tumor type
RAD51 DNA damage induced foci
HRD and Sensitive
HR Proficient and Resistant
HRD is Strongly Linked with Cancer
Breast
Ovarian
H&N
NSCLC
BRCA1
ATM
BRCA2
MDC1
BRCA1
ATM
BRCA2
Mre11
ATM
Mre11
Mre11
BRCA
TN Breast
FANC
CHK2
ATM
MDC1
Serous Ovarian
BRCA
MDC1
ATM /MRE11
GI, HCC
Mre11
Head & Neck
ATM /MRE11
Pancreas
Paediatrics
BRCA1
FANC
BRCA2
NSCLC
MDC1
CRC
MRE11
CFA Analysis of Breast Cancer Lines using Olaparib
25 cell lines from the Slamon breast cancer panel
Olaparib IC50 LOG [µM]
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
1
10
0.1
Non-luminal / basal (n=7)
Non-luminal / post-EMT (n=11)
0.01
0.001
Luminal (n=7)
Alan Lau; Richard Finn & Dennis Slamon
Response to Olaparib by HR Status
Triple Negative cell lines (n=14)
%Sensitive (< 1µM)
%Insensitive
HRD (n=12)
%Sensitive (< 1µM)
%Insensitive
25.00
43.75
56.25
75.00
ER-, PR -, Her2+ cell lines (n=11)
%Sensitive (< 1µM)
%Insensitive
22.22
77.78
HR proficient (n=13)
%Sensitive (< 1µM)
0.00
100.00
%Insensitive
Olaparib Inhibits Growth of HRD Tumors in vivo
MDA-MB-231
(HR proficient)
MDA-MB-468
(HRD)
5.0
4.0
Vehicle
AZD2281
4.0
Vehicle
AZD2281
3.5
Mean relative tumour volume
Mean relative tumour volume
4.5
3.5
3.0
2.5
2.0
1.5
1.0
3.0
2.5
2.0
1.5
1.0
0.5
0.5
0.0
0.0
0
2
4
6
8
10
12
Time (days)
14
16
18
20
0
2
4
6
8
10
12 14
16
18
20
22
24
26
28
Time (days)
MDA-MB-231 (HR proficient) and MDA-MB-468 (HRD) triple-negative cells were implanted s.c. on the flank of female nude mice. At tumour
volumes of 100-200mm3, mice were treated with vehicle or olaparib (100mg/kg) administered IP once daily (n=8 for each group). Data are
presented as mean relative tumour volume (mean RTV) and error bars represent SEM.
Aaron Cranston (KuDOS) & Richard Finn (UCLA)
Olaparib in Spontaneous BRCA2-Deficient Tumors
Relative Tumour Volumes
30
25
Vehicle
PARPi qdx28 i.p. 50mg/kg
RTV
20
Mean RTV
day 28 = 15.3
15
10
5
Mean RTV
day 28 = 1.20
0
0
5
10
15
Days after treatment
20
25
30
BRCA2-deficient KO Mice
From Targeted Therapy to the
Olaparib Phase I Study
 Oral, small molecule PARP inhibitor
 IC50 for PARP1 enzyme in the low nM range
 Phase I trial began at RMH then NKI; later expanded to
other centres
 Escalation phase: All tumor types
 Primary objectives of safety and tolerability
 Expansion phase: BRCA mutation carriers (HR deficient)
especially ovarian cancer
 Further assessment of efficacy
Overall Recruitment
 Escalation Phase (n=46)1,2
 Various tumor types; BRCA carrier status not mandatory
 10 dose level cohorts:
 10mg daily given for 2 out of 3 weeks
 600mg bid continuous dosing
 11 BRCA carrier ovarian cancer
 Expansion phase (n=52) at 200mg bid continuous2
 Confirmed BRCA mutation carriers
 39 ovarian cancer
1Fong
2Yap
et al. Proceedings of ASCO 2006
et al. Proceedings of ASCO 2007
Demographics
BRCA-Mutated Ovarian Cancer Subpopulation
Characteristics
BRCA1 / BRCA2 / Family history
Median age (range)
ECOG PS 0-1
Median duration from diagnosis to treatment (range)
Platinum status
Sensitive (PD > 6 months after platinum)
Resistant (PD ≤ 6 months after platinum)
Refractory (PD on platinum or on completion of
platinum)
Median no. of prior systemic therapies (range)
Number
41 / 8 / 1
52 (37-80) yrs
47
4.7 (0.5–16) yrs
10
27
13
3 (1-8)
Toxicities
first 60 patients, all tumor types)
 Most toxicities were Grade 1-2 (≥95%)
 Most common toxicities were:
 nausea 28%, vomiting 18%, dysgeusia 13%, anorexia 12%
 fatigue 28%
 Grade 3-4 toxicities were rare:
 myelosuppression (≤5%)
 nausea and vomiting (2-3%)
 CNS: dizziness or mood changes (2-3%)
 Pattern of toxicity similar in BRCA mutation carriers
Dose Limiting Toxicities (DLT)
Dose (mg)/
Schedule
Tumour type
400 bid
continuous
Ovarian Ca
600 bid
continuous
Mesothelioma
600 bid
continuous
Breast Ca
DLT
Outcome
G3 low mood and
Resolved within 24 hours of drug
discontinuation
G3 fatigue
G4 thrombocytopenia
G3 somnolence
Recurred with re-challenge
Resolved 2 weeks after drug
discontinuation
Resolved within 24 hours of drug
discontinuation
G1 on lower dose
Maximum Tolerated Dose (MTD) = 400mg bid
Response to Olaparib by Platinum-Free Interval
Total
Platinum
sensitive
Platinum
resistant
Platinum
refractory
46
10
25
11
Responders by RECIST
13 (28%)
5 (50%)
8 (32%)
0 (0%)
Responders by GCIG CA125
18 (39%)
8 (80%)
8 (32%)
2 (18%)
Responders by either RECIST or
GCIG criteria
21 (46%)
8 (80%)
11 (44%)
2 (18%)
6 (13%)
1 (10%)
4 (16%)
1 (9%)
24 (10-77)
23 (16-77)
24 (10-65)
26 (20-32)
No. of evaluable patients
SD (> 4 cycles)
Median duration of response in
weeks (range)
Platinum-free interval (months)
Platinum Sensitivity Correlated
with Response to Olaparib
24
Resistant
Sensitive
Refractory
18
12
6
0
CR/PR
SD >4 months
PD
23 mm
Ovarian BRCA1-/-
12 mm
6.8 mm
Breast BRCA?
21.05.07
03.04.07
6.5 mm
3 mm
Olaparib Resistance
 Pre-clinical
 Over expression of pgp (olaparib is pgp substrate)
 Reactivating BCRA mutation
 Clinical
 Todate no evidence of PARP inhibitor resistence
 Note: Platinum resistence has been shown due to
reactivating BRCA mutation
Olaparib Overcoming Drug Resistance
 Pre-clinical
 Overcome TMZ resistence
 Potentiation of chemotherapy, e.g. TMZ
 Clinical
 No data yet
Summary
 AZD2281 is a potent inhibitor of PARP and has
impressive clinical activity in BRCA patients with breast
and ovarian cancer
 The drug has additional potential to benefit a larger
group of patients with HRD tumors
 Patient selection is key to the success of this project
and is a paradigm for personalized health care
 The development of biomarkers and a diagnostic are
complex but pivotal to:
Delivery of the right drug, at the right dose to the right patient
Acknowledgements
 The patients and their families
 Royal Marsden Hospital
 Janet Hanwell
 Dimitrios Magkos
 Netherlands Cancer Institute
 Jana van der Sar
 Marja Voogel
 Edinburgh Cancer Centre
 UZ Brussel Oncologisch Centrum
 International Hereditary Cancer Centre,
Poland
 Jan Lubinski
 Cancer Research UK
 Institute of Cancer Research/
Breakthrough Breast Cancer Research UK
 Andrew Tutt
 Pei-Jun Wu
 Alan Ashworth
 AstraZeneca
 John Stone
 Mark O’Connor
 Helen Swaisland
 Peter Mortimer
 Jim Carmichael
 Clinical teams
 Theradex UK
 FECS/AACR/ASCO Methods in Clinical
Cancer Research Workshop, Flims, 2005