PARP Inhibitors for the treatment of MPNST

Christine Kivlin, Roman Belousov, Gonzalo Lopez, Quan-Sheng Zhu, Kai-Lieh Huang, Davis Ingram,

Keila E. Torres, Alexander J. Lazar, Raphael E. Pollock, Dina Lev

Sarcoma Research LaboratoryUniversity of Texas, MD Anderson Cancer Center

Malignant Peripheral Nerve Sheath Tumor (MPNST)

• Accounts for 3–10% of soft tissue sarcomas

• Up to 1,200 new cases in the U.S. per year

• High metastatic potential

• Neurofibromatosis type I (NF1)-related cases (50%) and sporadic (50%)

• Associated with a precursor lesion (NF1-related, deep neurofibromata)

MPNST treatment and outcome

• Surgical excision is the

mainstay of treatment

• Radiation/chemotherapy =?

• High rate of local and systemic recurrence

Zou et al., 2009

There is a critical need for novel effective

therapies in MPNST

PARP inhibitors for the treatment of cancer

• PARPi have been used in clinical trials over the past few years for common cancers, role for sarcoma unknown

• Tumors with DNA repair defects are most highly sensitive

The goal of our studies was to determine the effects of

PARP inhibitors on MPNST in vitro and in vivo

Experimental Models

Lopez et al., 2011

Time (weeks)

Tu

mo

r vo

lum

e (m

m3)

PARPi treatment reduces PARP activity

MPNST 724

PARP inhibitor (10uM)

Rel

ativ

e P

AR

P A

ctiv

ity

AZD2281Olaparib

(AstraZeneca)

ABT888Veliparib

(Abbott Laboratories)

BSI201Iniparib

(Sanofi Aventis)

MPNST 26T

PARP inhibitor (10uM)

Rel

ativ

e P

AR

P A

ctiv

ity

Decrease in cell proliferation with AZD2281

AZD2281 (uM)

% c

ell g

row

thControl Cell lines96 hour treatment

Decrease in cell proliferation with AZD2281

MPNST Cell Lines96 hour treatment

NSC

724

26T

ST88

462

AZD2281 (uM)

% c

ell g

row

th

AZD2281 treatment decreases colony forming ability

AZD2281 (uM)

MPNST 724

control 5.0 10.0 0.6125 1.25 2.5

AZD2281 causes G2/M cell cycle arrest

control 2.5uM AZD 5.0uM AZD 10.0uM AZD

G2/M: 53.217% G2/M: 66.366% G2/M: 79.795%G2/M: 22.794%

MPNST 72424 hour treatment

G1

SG2

G1

G1

G1S S S

G2 G2 G2

AZD2281 induces apoptosis

control 2.5uM AZD 5.0uM AZD 10.0uM AZD

MPNST 72496 hour treatment

8% total apoptosis 30% total apoptosis 35% total apoptosis 42% total apoptosis

Effect on tumor growthMPNST Xenograft: Subcutaneous Injection (16 mice)

Tumors grow to 5mm

Treatment (8 mice)50mg/kg/day AZD2281

Vehicle (8 mice)PBS+10%DMSO+10%HPCB

Sacrifice mice when vehicle group reaches 1500mm3, measure tumor volume and weight, preserve tissue

Intraperitoneal injection

AZD2281 abrogates tumor growth

* p= 0.0002

*p= 0.0002

MPNST 724MPNST 724 MPNST 26T

p= 0.0002*

Conclusions• MPNST cells are relatively sensitive to

PARP inhibition in vitro– Decrease in cell proliferation– G2/ M cell cycle arrest– Enhanced apoptosis

• Anti-tumor effect of PARPi in vivo– Cytostatic effect on tumor proliferation– Role of PARPi in combination with

chemotherapy preclinical/clinical trials?

Acknowledgements

PARP Function and Inhibition

PARP Activity Assay

Histone- coated strip wells

AZD2281ABT888BSI 201

-Add PARPi of interest

-Add cell lysate

-Add PARP cocktail, incubate

NAD

Add TACS Sapphire

Add HCl

Read Absorbance at 450nm

Biotinylated NAD:

Strepavidin HRP:

+ -

The chromosome # in this cell line ranged from 47-91 , the modal chromosome # being 58

724

Complex MPNST Karyotype

Rad5137kDa

NS

C

26T

724

462

ST

88

T26

5

Β-Actin

NSC

26T

724

462

T265

ST88

PARP 1

B-Actin

DNA damage PCR array Results