The story of the ATM gene in CLL:Bench and Bedside

Tatjana StankovicSchool of Cancer Sciences, University of Birmingham

B cell chronic lymphocytic leukaemia

•Occurs in elderly individuals over age of 60

•Incidence 3680 new cases every year in UK

•Prevalence 6.5 in 100 000 individuals

•Currently incurable by chemotherapy

B-cell chronic lymphocytic leukaemia (B-CLL) has a variable clinical course

Time from diagnosis Ris

e in

lym

ph

ocyte

cou

nt

Indolent disease

Progressive leukaemia

Progressive disease associated with:Unmutated VH genesHigh Zap70, CD38 expressionDel 17p, 11q (loss of single TP53 or ATM allele)Genomic complexityShort telomeres

VDJ recombination, Irradiation, chemotherapy, OxidativeMetabolism cause DNA Double strand breaks (DSBs)

APOPTOSIS

p53

Chk2

DNA REPAIRCELL CYCLE

Responsive genes

Accumulation ofDNA damage

Occurrenceand progression

of lymphoid tumours

ATM

AB

Mre11Nbs1

Mre11Mre11Nbs1

Mre11 AB

Rad50

Rad50

Zn2+

Zn2+ Head Arm

Complete inactivation of ATM is frequent in Chronic Lymphocytic Leukaemia:

Leukaemiawith intact ATM

Leukaemiawith loss of ATM

SkinTumour Hair

1058delGT 1058delGT1058delGT

Up to 40% of patients have ATM mutations in their tumour cellsC

LL1

CLL2

CLL3

CLL4

CLL5

CLL1

CLL2

CLL3

CLL4

CLL5

ATM segment I ATM segment VI

Stankovic et al, Lancet, 1999

p53

Apoptosis

DSB

ATMP

B-CLL47 B-CLL7 B-CLL35 B-CLL9

WT Mut Mut WT

WT WT WT Mut

Actinp53

ATM status

TP53 status

- + - + - + - +IR

Pettit et al, Blood 2001, Stankovic et al, Blood 2002

1. DNA damage response defect

2. Defective IR induced apoptosisIn vitro

Stankovic et al, Blood 2002Austen et al, JCO 2007

% P

ARP1

at 2

4h

100

80

60

40

20

ATM wt ATM mutant TP53 mutant

p=0.0019

ATM-dependent

repair

Activation of cell cycle

check-points

ATM mut

DSB

ATM mutations in CLL alter DNA damage response

3. DNA damage response defectrequires inactivation of both ATM alleles

CLL1380 24

CLL370 24

CLL1090 24

CLL1690 24

p53 S15P

SMC1 S966P

ATM S1981P

SMC1

Actin

p53

Hours of treatment

11q deletion and

wild type ATM allele

2 wildtypeATM alleles

11q deletionand

mutantATM allele

Fludarabine15µm

Austen et al, JCO 2007

ATM mutations affect patients’ survivalUnselected cohort (18/155) 12%

Time in months

Perc

en

tag

e a

l ive

p<0.0001

TP53 mutant (n=6)

ATM mutant (n=15)

ATM/TP53 wild type (n=133)

0102030405060708090

100

020

4060

80100

120140

160180

200

Overall survival

0

10

20

30

40

50

60

70

80

90

100

Perc

en

tag

e t

reatm

en

t fr

ee

Time in months

TP53 mutant (n=6)

ATM mutant (n=15)

ATM/TP53 wild type (n=133)

p=0.0153

020

4060

80100

120140

160180

200

Time to First Treatment

UK CLL4 –First line treatment: Chl vs F vs FC (36/224) 14.7%

Progression Free Survival

No TP53 or 11q abnormality11q deletion

TP53 mutation or 17p deletionATM mutation + 11q deletionTP53 mutation + 17p deletion

<0.001

11q cohort (26/72) 36%

0 50 100150 200250300350Months since diagnosis

0.0

0.2

0.4

0.6

0.8

1.0

Pro

port

ion

of

pati

en

ts a

live

11q deletion and mutant ATM allele

11q deletion and wild type ATM allele

p=0.0283Overall survivalP

erc

en

tag

e w

ith

ou

t p

rog

ressio

n

ATM null leukaemias require alternative, personalized treatment

Survival

DNADamag

e

PARP inhibition (Olaparib)

ATM defect

Conversion of Single Strand Breaks to

Double Strand Breaks

Conversion of Single Strand Breaks to

Double Strand BreaksSingle strand break repair

Homologous

Recombination

Victoria Weston Ceri Oldreive

Tu

mou

r siz

e m

m

0

500

1000

1500

2000

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Time post-treatment initiation (days)

3 No treatment (n=20)Olaparib (n=15)

××××× ××

×××××××××

Mimicking a clinical trial in patients

No treatment Olaparib

Phase I/II clinical trial to assess the efficacy and safety of Olaparib, a PARP-Inhibitor, in

relapsed and refractory Chronic Lymphocytic Leukaemia patients with an

11q deletion or ATM mutation and relapsed/refractory patients with T-

Prolymphocytic Leukaemia and Mantle Cell Lymphoma.

Guy Pratt Nicola Fenwick

PICCLE Trial

Response rate at 16 weeks

Clinical and laboratory assessmentATM analysis

Olaparib 200 mg bd->400mg bd

Patients with refractory

CLL and 11q del

1 16Weeks

Trial Objectives

Primary Objective:

– Phase I:To identify the maximum tolerated dose (MTD) of olaparib

– Phase II: To assess the efficacy of Olaparib in patients with ATM-deficient CLL

Exploratory Objective:– Develop biomarkers for the activity of this agent

Planned Recruitment:– Phase I: 18 patients (maximum) – Phase II: 58 patients

From ATM gene to leukaemia patients: return to bedside

20111999

Clinical trialwith Olaparib

Clinical significance of ATM mutationsATM function

Concept of synthetic lethality

ATM mutationsin the most frequent

blood cancer

Survival

DNADamag

e

ATM defect

Judy Powell

Paul MossGuy PrattDavid OscierChris FeganMartin DyerPam Kearns

Acknowledgements

Malcolm TaylorPhil Byrd

Victoria WestonCeri OldreiveAngelo AgathanggelouAnna SkowronskaGulshanara AhmedEliot MarstonKatie MappBelinda Austen

KuDOS/Astra Zeneca Pharmaceuticals