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Deficient homologous recombination DNA
repair appears to cluster sarcoma patients
sensitive to trabectedin (ET-743, Yondelis®)
Maki RG, Taron M, van Oosterom AT, Schöffski P,
Tercero JC, Fernandez Sousa-Faro JM, Jimeno JM, Rosell R
Memorial Sloan Kettering Cancer Center, New York, NY;
Hospital Germans Trias i Pujol, Badalona, Barcelona, SPAIN
UZ Gasthuisberg, Leuven, BELGIUM
PharmaMar Research and Development, Madrid, SPAIN
Introduction
ET-743 (trabectidin, Yondelis®) is a marine-derived compound
in phase II-III development for solid tumors
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Binds to the minor groove of DNA
Interacts with transcription factors and DNA binding proteins
Disorganizes of the microtubule network
Perturbs the cell cycle
Interferes with DNA repair pathways
E. turbinata
Van Kesteren et al. Anticancer Drugs. 2002; 13:381
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ET-743 sarcoma program: combined
phase II results
ET-743 induces long-lasting responses and tumor control in a clinically
relevant proportion of patients.
PARAMETER
Full Cohort
(n=183)
Dox / Ifos Resistant (n=63)
PR
14 (8%)
6 (10%)
MR
14 (8%)
4 (6%)
SD
13 (7%)
5 (8%)
TUMOR CONTROL
41 (22%)
15 (24%)
PFS > 6 months
20%
22%
MEDIAN OS (months)
10.3
10.1
OS > 2 years (percent)
29%
26%
JA López et al. Proc. ASCO 2003; Abstr. 3293
A. Le Cesne et al, JCO 2005; 23:576
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ET-743 phase II sarcoma program:
Overall survival
Supervivencia Global
– ET -743 STS
Median Survival 10.3 months
29% of pts alive > 2 yrs
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Objective
Identify and validate molecular markers that correlate with
sensitivity or resistance to ET-743
– Select the group of STS patients who will most benefit from ET-743
Marker +
Marker -
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I. Identification of genes in vitro
associated with ET-743 sensitivity or
resistance
•
•
Human STS cell lines explanted from chemotherapy-naïve patients
12 low passage sarcoma cell lines sensitive or resistant to ET-743
underwent gene expression profile (CNIO Oncochip; > 6700 cancer
related genes)
MOLECULAR PROFILE OF ET-743
0h
6h
12h
24h
72h
STS cell lines
10nM ET-743
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Chemotherapy sensitivity profile of low
passage sarcoma cell lines
CELL LINE
TUMOR HISTOLOGY
ET-743
(nM)
Doxorubicin
(nM)
SR2103/A
LIPOSARCOMA
0.7
45
SR2103/B
LIPOSARCOMA
0.7
44
SW872
LIPOSARCOMA
0.5
>300
CA1010
LEIOMYOSARCOMA
0.4
21.5
LS0904
LEIOMYOSARCOMA
9
>300
SR2205
FIBROUS TUMOR
1
14
SR2410
MPNST
>100
>300
SR0406
MPNST
>100
not done
SR2910
EWING SARCOMA
1
5
A673
EWING SARCOMA
1
10
SR0312
OSTEOSARCOMA
0.4
15
RS0306
WILMS TUMOR
>100
60
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Genes differentially expressed in
ET-743 sensitive and resistant cell lines
• Cell cycle control
– TP53
• Inhibition of transcription and the DNA
damage response
– JUNB, ATF3, CS-1, SAT, ID2, GADD45B
• DNA repair
– BRCA1, XPD, RAD17, p31, p53DINP1
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II. DNA repair genes appear central to the
function of ET-743: gene deletion experiments
Intact
nucleotide
excision repair
increases
cytotoxicity
Deficient
double stranded
break repair
increases
cytotoxicity
Takebayashi Y. et al. Nature Med 2001; 7:961
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III. Examining genes involved in DNA
repair and how they are implicated in
patient responses to ET-743
• Source material: tumor samples from 45 heavily pretreated STS patients, subsequently treated with
ET-743
• Analyze genes important in DNA repair by mRNA
expression and / or analysis of single nucleotide
polymorphisms (SNPs)
(a) NER pathway: ERCC1 and XPD mRNA
expression and SNP analysis
(b) BRCA1 mRNA expression
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Best ET-743 response in patients
providing tumor samples
# Pts
PR
MR
SD(*)
PD
45
5
1
14
25
53 patients, 8 not evaluable;
Median Duration of PR or MR: 13.3 months
(*) 4 / 14 SD achieved PFS > 6 mo
10 / 45 PD achieved PFS > 6 mo
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Comparison of this cohort to the larger cohort of
analyzed patients
Overall survival
Median: 11.8 months
Progression-free survival
Median: 1.6 months
PFS > 6 months: 26 %
73% of this group were compassionate use patients:
Histology:
Leiomyosarcoma
31%
Osteogenic sarcoma
22%
Synovial sarcoma
16%
Prior chemo: Median # Regimens
Median # Agents
2 (0-6)
2 (0-10)
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Experimental design
Paraffin
embedded
tumor tissue
DNA extraction
Reverse transcription
Q-RT-PCR
Allele discrimination
RT-PCR
Gln
RNA extraction
Gln/G
ln
Lys/G
ln
Lys/Ly
s
NTC
Lys
Lys XPD 751 Lys
Lys XPD 751 Gln
Gln XPD 751 Gln
Quantitation of
RNA expression level
Identification of
polymorphic DNA
alleles
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XPD polymorphisms associated with
responses to ET-743
Polymorphism
Patients
PR
Lys751Lys
Asp312Asp
14
15
3
3
Gln751Gln
Asn312Asn
5
7
0
0
There is a trend in the association between Lys751Lys and
Asp312Asp genotypes in XPD gene and better clinical response
to ET-743 in sarcoma patients (but p=NS by Fisher’s exact test).
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High or low ERCC1 and XPD expression and
their association with overall survival
PFS by ERCC1
PFS by XPD
high
high
low
low
Cut-off expression level = 5.86
Cut-off expression level = 1.95
Patients with high levels of expression of both ERCC1 and XPD
show trend toward better tumor control rates ( PFS > 6 months )
p=NS by Fisher’s exact test
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ERCC1 expression and sensitivity to ET-743
Parameter
ERCC1 mRNA
Expression Levels
< median
PR + MR / Total (%)
PFS > 6 months
2 / 19 (11%)
3 / 19 (16%)
>
median
4 / 19 (21%)
6 / 19 (32%)
Patients with high levels of ERCC1 expression
showed a trend toward better RR (21% vs. 11%) and a higher
rate of patients achieving PFS > 6 months (32% vs 16%)
(p = NS by Fisher exact test)
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BRCA1 expression and ET-743 sensitivity
Parameter
BRCA1 expression levels
< median
PR + MR (%)
PFS > 6 months (%)
4 / 17 (24%)
6 / 17 (35%)
> median
1 / 17 (6%)*
1 / 17 (6%)++
*p = 0.3
++p = 0.08
Patients with low BRCA1 mRNA expression levels demonstrated a
trend towards higher PR+MR and tumor control rates
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Kaplan-Meier survival curves by
BRCA1 expression
PFS
Survival
p = 0.06
p = 0.02
Low
Low
High
High
PFS > 6 month rate:
BRCA1 < median:
BRCA1 > median:
41 %
6%
Total population :
Phase II pivotal:
26 %
20 %
Median survival:
BRCA1 < median: 16.8 months
BRCA1 > median: 6.0 months
Total population:
Phase II pivotal:
11.8 months
10.3 months
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Conclusions
• Preclinical analysis of cell lines sensitive or resistant to ET-743
identifies a set of genes that underscores the importance of DNA
repair (intact NER) in the mechanism of action of ET-743.
• Low expression of BRCA1 is associated with better objective
response, higher rate of progression free survival at 6 months,
and a statistically significant improved median survival of sarcoma
patients treated with ET-743.
• High expression levels of XPD or ERCC1 may be associated with
improved clinical outcome on ET-743
• Lys751Lys and Asp312Asp genotypes in the XPD gene also
appear to be associated with a higher rate of response to ET-743.
• Analysis of a larger group of tumors from patients sensitive and
resistant to ET-743 will be necessary to confirm the relationship
between DNA repair genes and ET-743 sensitivity.
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Thank you for the opportunity to present.
Positano, Italy
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