Giuseppe Fornarini, U.O. Oncologia Medica 1 Ospedale Policlinico San Martino
IRCCS Genova
Trattamenti della malattia con mutazioni
di BRCA e altro…
Background
• Prostate cancer is inheritable…but
• Important to know the family history
• A different type of genes are involved…BRCA1/2, Lynch Syndrome…others
• Pts with BRCA2 mutation have 3-9x risk of PC and more lethal
• Germline could be different from somatic mutation
• In advanced disease clinical management does not differ
• To whom should we offer germline genetic testing
and when… because
To whom should we offer germline genetic testing?
Presented By Heather Cheng at 2018 ASCO Annual Meeting
Germline pathogenic alterations may have both
familial and therapeutic implications
More recent genetic findings in advanced PC may also inform therapy
Presented By Heather Cheng at 2018 ASCO Annual Meeting
Outline
• The 6 DNA repair pathways
• Prevalence of DNA repair defects in prostate cancer
• DNA repair and therapeutic implications
– PARP inhibitors – Hormonal therapy
– Immune checkpoint inhibitors – Platinum chemotherapy
Emmanuel S. Antonarakis, MBBCh
Single-Stranded (ss)DNA Repair Pathways
• Mismatch repair
– Base errors from DNA replication and recombination – MSH2, MSH6, MLH1, PMS2
• Nucleotide excision repair
– DNA damage from UV light, polycyclic aromatic hydrocarbons – XPA-G, ERCC1-8, CSA/B, RPA, RAD23A/B
• Base excision repair
– DNA damage from alkylation, oxidation/ROS, deamination – PARP1/2/3, POLβ, MUTYH, XRCC1, MBD4, NTHL1
Mateo J, et al. Eur Urol. 2017;71:417-425.
Emmanuel S. Antonarakis, MBBCh
Double-Stranded (ds)DNA Repair Pathways
• Homologous recombination
– DNA damage from ionizing radiation or other dsDNA injury
– FANC genes, BRCA1/2, ATM, PALB2, RAD50, RAD51, NBN, GEN1, MRE11, BLM, ATR
• Nonhomologous end joining
– DNA damage from ionizing radiation or other dsDNA injury – XRCC4/5/6, LIG4, DCLRE1C, PRKDC, NHEJ1, POLL/M
• Translesion DNA synthesis
– Error-prone recovery mechanism when no DNA template
– POLH, POLI, POLK, PCNA, REV1/3 (error-prone DNA polymerases)
Mateo J, et al. Eur Urol. 2017;71:417-425. Makridakis NM, et al. Front Genet. 2012;3:174.
Emmanuel S. Antonarakis, MBBCh
• 11.8% (82/692) of men with metastatic prostate cancer
inherited a germline DNA repair mutation vs 4.6% of
499 men with localized disease
Germline Mutations in Prostate
Cancer: 1 in 10
Pritchard CC, et al. N Engl J Med. 2016;375:443- 453.
Distribution of Presumed Pathogenic Germline
Mutations
PALB2 4%
RAD51D 4%
ATR 2%
NBN 2% PMS2 2% GEN1 2% MSH2 1% MSH6 1% RAD51C
1% MRE11A 1% BRIP1 1%
FAM175A 1%
BRCA2 44%
ATM 13%
CHEK2 12%
BRCA1 7%
Gene No. of Mutations
% of Men
BRCA2 37 5.35
ATM 11 1.59
CHEK2* 10 1.87
BRCA1 6 0.87
Presumed Pathogenic Germline Mutations
in Metastatic Cases (N = 692)
*n = 534; data censored for metastatic cases with inadequate sequencing.
• Germline mutations in 14% (21/150) of men with
recurrent/advanced prostate cancer
• Men with intraductal/ductal histology more likely to have germline mutations
Association Between Germline DNA- Repair Defects and Intraductal/Ductal
Histology
Isaacsson Velho P, et al. The Prostate. 2018;[Epub ahead of print].
Intra/Ductal Histology
No
Intra/Ductal Histology
P Value*
40% (10/25) 9% (11/125) P = .003
*Fisher’s test.
Incidence of Pathogenic Germline Mutations
Distribution of Pathogenic Germline Mutations
CDH1 5%
MSH6 5%
PALB2 5%
NBN 5%
BRCA2 43%
CHEK2 14%
ATM 14%
BRCA1 9%
Emmanuel S. Antonarakis, MBBCh
Effect of DDR Mutation on Treatment Responses
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
Selected Trials for mCRPC with Relevance to DNA repair defects
Presented By Heather Cheng at 2018 ASCO Annual Meeting
PARP Biology
• A key role in the repair of ssDNA breaks via BER pathway
• Binds directly to sites of DNA damage
• Once activated, uses NAD as a substrate to add large, branched chains of poly(ADP-ribose) polymers (ie, PARylation) to itself and interaction partners
• Recruits other DNA repair enzymes to site of damage
Ohmoto A, et al. Onco Targets Ther. 2017;10:5195-5208.
DNA damage
NAD+ Nicotina
mide + pADPr
Lig3 XRCC1
Polß PNK PARP
Emmanuel S. Antonarakis, MBBCh
PARPi Leads to Increase in dsDNA Breaks
• Inhibition of PARP:
– Prevents
recruitment of DNA repair
enzymes to ssDNA breaks, or traps PARP on DNA – Leads to failure
of ssDNA repair and accumulation of ssDNA breaks – Replication fork is
arrested at
damage, produces dsDNA breaks
Ohmoto A, et al. Onco Targets Ther. 2017;10:5195-5208.
PARP
During S-phase, replication fork is arrested at site of ssDNA breaks
Degeneration into dsDNA breaks
ssDNA breaks PARP
inhibition
XRCC1
DNA Lig III PNK 1
DNA Polβ
Emmanuel S. Antonarakis, MBBCh
Synthetic Lethality Hypothesis
Farmer H, et al. Nature. 2005;434:917-921. Bryant et al. Nature. 2005;434:913-917.
Repair, Survival
Repair, Survival
Normal cell
Non-BRCA mutation carrier PARP function
BRCA function
PARP inhibitor
PARP function BRCA function
DNA damage
Repair, Survival
Repair, Survival
Normal cell
BRCA mutation carrier
(1 allele lost) PARP function BRCA function
PARP inhibitor
PARP function BRCA function
DNA damage
Repair,
Survival
Cell Death
Cancer cell
BRCA mutation carrier
(both alleles lost)
PARP function BRCA function
PARP inhibitor DNA damage
PARP function BRCA function
Emmanuel S. Antonarakis, MBBCh
TOPARP
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
TOPARP Results: Response
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
TOPARP Results
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
Single Agent Trials In Progress
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
Slide 17
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
Combination Trials In Progress
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
Clinical Data Extrapolations
Presented By Carmel Pezaro at 2018 ASCO Annual Meeting
DNA Repair Defects and
Hormonal Therapy
Abiraterone in mCRPC With HR Deficiency
• 20/80 (25%) evaluable pts with mCRPC had DNA repair defects
Hussain M, et al. J Clin Oncol. 2017;[Epub ahead of print].
PFS by DRD Status DNA Repair Defects*
BRCA2 ATM BRC RAD5A1 RAD511B PALB2 C
FANCA
Frameshi ft
Nonsens e
Not detected In-frame indel Copy-neutral
LOH Missense
+ Censored
Log-rank P = .0254 Median, Mos (95%
CI)
DRD: 14.5 (11.0- 19.5)
WT: 8.1 (5.5-11.0)
Probability of PFS
Mos
0.20.4 0.6 0.8 1.0
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42
20 19 13 6 4 3 2 1 20
43 34 20 10 5 3 0 60
DRD WT Pts at Risk, n
*Data shown for 25 of 80 pts with exploratory tumor sequencing.
Biallelic Monoallelic
2 copy losses 1 copy loss
Emmanuel S. Antonarakis, MBBCh
Abiraterone or Enzalutamide and HR Deficiency
PFS by DRD Status
Antonarakis ES, et al. Eur Urol. 2018. In press.
PFS (%)
0 6 12 18 24
20 40 60 80 100
0
Any Mutation No
Yes (other)
Yes (ATM/BRCA1/BRCA2)
Mos
Yes (other) Yes (ATM/BRCA1/
BRCA2) Pts at Risk, n
150 102 60 38 18
13 9 6 4 3
9 8 6 4 3
No
OS by DRD Status
Any Mutation No
Yes (Other)
Yes (ATM/BRCA1/BRCA2)
OS (%)
20 40 60 80 100
0
0 6 12 18 24 30 36 42 48
Mos
Yes (other) Yes (ATM/BRCA1/
BRCA2) Pts at Risk, n
No 150 145 128 75 75 52 35 22 11
13 13 13 9 8 6 5 3 0
9 9 8 7 6 4 4 4 0
Emmanuel S. Antonarakis, MBBCh
Abiraterone vs Enzalutamide and HR Deficiency
• Randomized phase II
crossover study in treatment- naive pts with mCRPC (N = 202)
• BRCA2- or ATM-truncating
mutations or rearrangements:
– Somatic (ctDNA): 6/115 (5.2%)
– Germline (WBC): 8/202 (4.0%)
• Monoallelic BRCA2 or ATM deletion in 21 pts
– No TTP differences (P = .205)
Annala M, et al. Cancer Discov. 2018;[Epub ahead of print].
Time to Progression by HRR Status*
*Abiraterone + enzalutamide arms combined.
8 2
6 6
4 1
2 9
1 4
5 3 1 1
0 5
6 2
3 3
1 7
8 5 2 0 1
4
2 0 0 0 0 0 0 Pts at
Risk, n
Probability of PFS
0 4 8 1 2
1 6
2 0
2 4
2 8 0.
2 0 0.
6 0
. 4 1.
0 0
. 8
Mos
HR P Value PSA > 40 ng/mL 1.50 .032
LDH > ULN 1.87 .008 ALP > ULN 1.16 .496 Hemoglobin < 130 1.45 .055 Visceral mets 2.27 .004 ECOG PS 2 1.26 .327 ctDNA > 2% 1.44 .086 HRR defect 5.27 < .001
HRR defect Yes No
ctDNA unquantifiable
Emmanuel S. Antonarakis, MBBCh
DNA Repair Defects and
Immune Checkpoint Inhibitors
KEYNOTE-016: Responses to
Pembrolizumab in MMR-Deficient Tumors
• Radiographic responses across 12 tumor types at 20 wks (N = 86)
Le DT, et al. Science. 2017;357:409-413.
Ampulla of Vater Cholangiocarcinoma Colorectal
Endometrial cancer Gastroesophageal Neuroendocrine Osteosarcoma Pancreas
Prostate
Small Intestine Thyroid
Unknown primary
100 50 0 -50 -100 Change F rom Ba se li ne SL D (% )
Prostate
Prostate (n = 1)
Emmanuel S. Antonarakis, MBBCh
MMR Mutations in mCRPC
• 4/150 (2.7%) mCRPC pts were MSI-high, 3 of
whom had MMR mutations (2%)
– 13 mut/Mb (Pt #149) – MSH2
– 21 mut/Mb (Pt #147) – no MMR mutation
– 23 mut/Mb (Pt #148) – MSH2
– 25 mut/Mb (Pt #150) – MSH2 and MLH1
Robinson D, et al. Cell. 2015;161:1215- 1228.
MSI Analysis:
Hypermutated vs Nonhypermutated CRPC
Fraction Unstable Loci
0 50
0
100 0
150 0 0.1
0 0 0.3
0 0.2
0 0.5
0 0.4
0
Nonsynonymous Mutations
Negative MSI Positive
149
147
148 150
32, 41, 49, 67, 93
Emmanuel S. Antonarakis, MBBCh
MMR Mutations Can Cause HRD Mutations
• This patient should be treated with a PD-1 inhibitor, not a PARP inhibitor
Patient Case Gene Mutation
Primary MMR mutation MSH2 E809X* + LOH = MSI-high (> 100
mut/Mb) Secondary DNA-repair
mutations
BRCA2
ERCC4
ERCC5
FANCM
MSH6
E1646fs*
M361fs*
E474fs*
V1336fs*
F1104fs*
*Protein truncation by stop codon (X) or frameshift (fs).
Emmanuel S. Antonarakis, MBBCh
MMR Defects in Prostatic Ductal Carcinoma
• 4/10 (40%) had MMR mutations; 3/10 (30%) had MSI and hypermutation
Schweizer MT, et al. Oncotarget.
2016;7:82504-82510.
Pt No.
Ductal Component
for NGS, %
Est. Tumor Content From NGS, %
MMR Gene Alteration HR Gene Alteration Hyper- mut
Total Coding Muts/1.2 Mb Sequenced
1 71 30 No CHEK2 c.1100delC + LOH No 4
2 45 40 MSH2 inversion No No 4
3 65 60 No No No 4
4 30
60 MSH6 c.1900_1901del + LOH No Yes 29
5 97 50 MSH2-GRHL2 rearrangement +
LOH No Yes 34
6 99 50 No No No 5
7 25 0 -- -- -- --
8 31 70 No No No 5
9 35
10 No BRCA2 c.594delT + likely LOH No 3
10 -- 60 MLH1 exon 19+ 3’UTR
homozygous deletion No Yes 32
Emmanuel S. Antonarakis, MBBCh
MMR Defects and Gleason Grade
• 1.2% (14/1176) of primary adenocarcinomas and NEPC had MSH2 protein loss by IHC
• Pathology and MSH2 loss
– Primary Gleason pattern 5 enriched for MSH2 loss: 8%
(7/91)
– MSH2 loss in pts with any other Gleason score: < 1%
(5/1042) – P < .05
Guedes LB, et al. Clin Cancer Res.
2017;23:6863-6874.
Cases with MSH2 loss
Controls without MSH2 loss P =
.008
CD 8 (ce ll s/m m
2)
1200 1000 800 600 400 200 0
Emmanuel S. Antonarakis, MBBCh
DNA Repair and
Platinum Chemotherapy
Platinum Response in mCRPC With HR Deficiency
Cheng H, et al. Eur Urol. 2016;69:992- 995.
Clinical Treatment Course Clinical Treatment Course
Pt Allele BRCA2 Mutation Mutation Type
1 1 c.9196C>T; p.Q3066X Premature stop 2 127 bp del in exon 11 Fs deletion 2 1 c.8904delC; p.V2969Cfs *7 Fs deletion 2 c.2611delT; p.S871Qfs *3 Fs deletion
3 1 Homozygous copy loss Copy loss
2 Homozygous copy loss Copy loss
Pt 2
PSA (ng/mL)
7 0 6 0 5 0 4 0 3 0 2 0 1 0 0
2012 2013 2014 2015
5 mos
ABI ENZ DOC CAR
+DOX
Pt 1
PSA (ng/mL)
50 40 0 300 0 2 0 100 0 0
2012 2013 2014
18 mos
ABI ENZ
DOC CAR
+DOC CAR
+DOC CIS
+ETO
30 mos
ABI CAR PA
C CAR
+DOC
Pt 3
PSA (ng/mL)
1 2 1 0 8 6 4 2 0
2011 2012 2013 2014
CAR +DOC
*
*
Time of metastatic biopsy.*
*
Emmanuel S. Antonarakis, MBBCh
• Near-CR to cisplatin/docetaxel in a pt with metastatic NEPC, lasting 12 mos – Genome of metastatic tumor found to be highly altered; germline FANCA
mutation (S1088F) with somatic LOH also identified
– In preclinical studies, loss of FANCA associated with increased cisplatin sensitivity
0.01 10
Platinum Response in mCRPC With FANCA Deficiency
Beltran H, et al. JAMA Oncol. 2015;1:466-474.
Increased Cisplatin Sensitivity With Loss of FANCA
Xenograft Model Cell Culture
Model 130 110 90 70 50 30 10 Cell Viability (%) 0
0.1 1.0 100 Cisplatin IC50 (μM)
FANCA KO2 Control
IC50 0.8 μM 2.5 μM
Control KO2
FANCA GAPDH
800 600 400 200 0 1000
Tumor Volume (mm3 )
0 4 8 11 14 Days
Vehicle Cisplatin
Emmanuel S. Antonarakis, MBBCh
HR Deficiency and Response to Carboplatin
• 8/141 (5.7%) men with mCRPC had pathogenic germline BRCA2 variants
Pomerantz MM, et al. Cancer. 2017;123:3532-3539.
OS With
Carboplatin/Docetaxel by BRCA2 Carrier Status PSA Response With
Carboplatin/Docetaxel by BRCA2 Carrier Status
*Carriers of pathogenic germline variants in other DNA repair genes (MSH2, ATM, BLM, FANCA).
Observations (n=141)
BRCA2 carrier BRCA2 noncarrier Log-rank P = .03
Mos After Initiation of Carboplatin/Docetaxel
Probability of OS1.00
0.75 0.50 0.25 0
0 12 24 36 48 60 72 84 96
Pts at Risk, n BRCA2 noncarrier BRCA2 carrier
133 51 14 6 5 3 2 1 1 8 5 3 3 2 2 0 0 0 BRCA2 carrier
BRCA2 noncarrier
*
*
* *
PSA Decline (%)
0 25 50 75 100
Emmanuel S. Antonarakis, MBBCh
Conclusions
• Not all DNA repair lesions are created equal
• Somatic (and germline) DNA repair mutations are common in prostate cancer, particularly mCRPC
• HRD mutations may sensitize to PARP inhibitors, platinum agents
• MMR mutations may sensitize to immune checkpoint inhibitors
• The role of germline vs somatic, and single- vs double-copy inactivation, remains unclear
Emmanuel S. Antonarakis, MBBCh