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La biologia dei meccanismi di riparo del DNA
Nicola Normanno
ISTITUTO NAZIONALE PER LO STUDIO E LA CURA DEI TUMORI
FONDAZIONE G. Pascale – NAPOLISC Biologia Cellulare e Bioterapie
CENTRO RICERCHE ONCOLOGICHEMERCOGLIANO (AV)
Laboratorio di Farmacogenomica
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An overview of types of DNA damage and causal agents
Helleday Nat Rev Genetics 2014
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How the cell copes with damaged DNA
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Mechanisms of single strand DNA break repair
• Base excision repair (BER): is important for removing damaged bases by a DNA glycosylase and it is involved in the damage induced by radiation and alkylating agents
Toss & Cortesi J Cancer Sci Ther 2013
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Mechanisms of single strand DNA break repair
• Nucleic acid excision repair (NER): removes short single-stranded DNA segment around the lesion and repairs mutations resulting from UV light and hydrocarbons
Helleday Nat Rev Genetics 2014
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Mechanisms of single strand DNA break repair
• Mismatch repair (MMR): recognizes and corrects mismatched bases that can result from DNA replication and recombination
Helleday Nat Rev Genetics 2014
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Mechanisms of double-strand DNA breaks repair
• Homologous recombination (HR): provides accurate recombination using a sister chromatid as a template, maintaining genomic stability. However, due to the need for a sister chromatid, HR is limited to the S-phase and G2-phase of cell cycle
Helleday Nat Rev Genetics 2014
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Mechanisms of double-strand DNA breaks repair• Nonhomologous end joining
(NHEJ): plays a crucial role in minimizing DNA damage in both G0 and G1 phases of cell cycle, when HR cannot be supplied. Moreover, when a defect occurs in one of the enzymes involved in HR, the DSBs are repaired from error prone mechanisms, mostly NHEJ, resulting in increased risk of new chromosomal defects and thus the development of cancer
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Homologous recombination (HR)
Toss & Cortesi J Cancer Sci Ther 2013
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BRCA mutations are associated with sensitivity to platinum-based therapy
Patients carrying a BRCA mutation appear to show a favourable response to platinum-based therapy
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BRCA-mutant tumors are sensitive to targeted therapy via PARP inhibition
– In women with ovarian cancer and BRCA mutation, tumour cells are characterised by homologous recombination repair deficiency (HRD)
– PARP inhibitors are a class of targeted treatments that act on the DNA repair pathway1
– PARP inhibition can result in selective tumour cell death in BRCA1/2 mutation carriers with ovarian cancer1,2
1. Liu JF, et al. Gynecol Oncol 2014;133:362–9; 2. Fong PC, et al. J Clin Oncol 2010;28:2512–19
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DNA
damage
PARP
Formation of single
strand DNA break
(SSB)
Repair of of SSB by
Base Excision Repair
Mechanism of synthetic lethality
between BRCA deficiency and PARP inhibition
Banerjee, Kaye and Ashworth
(2010)
Courtesy of S.Banerjee
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DNA
damage
PARP
Formation of single
strand DNA break
(SSB)
Repair of of SSB by
Base Excision Repair
PARP inhibition Impairs base excision repairSSB persists
Mechanism of synthetic lethality
between BRCA deficiency and PARP inhibition
Banerjee, Kaye and Ashworth
(2010)
Courtesy of S.Banerjee
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DNA
damage
PARP
Formation of single
strand DNA break
(SSB)
Repair of of SSB by
Base Excision Repair
PARP inhibition Impairs base excision repairSSB persists
DNA replication: Replication fork arrests at SSB
Formation of double strand breaks (DSBs) or
replication fork collapse
Normal cell
with functional HR
pathway
HR-mediated
DNA repairCELL
SURVIVAL
Mechanism of synthetic lethality
between BRCA deficiency and PARP inhibition
Banerjee, Kaye and Ashworth
(2010)
Courtesy of S.Banerjee
-
DNA
damage
PARP
Formation of single
strand DNA break
(SSB)
Repair of of SSB by
Base Excision Repair
PARP inhibition Impairs base excision repairSSB persists
DNA replication: Replication fork arrests at SSB
Formation of double strand breaks (DSBs) or
replication fork collapse)
Normal cell
with functional HR
pathway
HR-mediated
DNA repair
Impaired
HR-mediated
DNA repair
TUMOUR-SELECTIVE CELL
DEATH (Synthetic Lethality))
CELL
DEATH
HR-deficient tumour cell
(BRCA deficient)
CELL
SURVIVAL
Mechanism of synthetic lethality
between BRCA deficiency and PARP inhibition
Banerjee, Kaye and Ashworth
(2010)
Courtesy of S.Banerjee
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Seminal Hypothesis(synthetic letality)
If you treat cells with impaired HR (i.e. BRCA1/2 defective) they should rely on low-fidelity NHEJ (errore-prone) machinery to repair DNA damage…
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Genetic Mutations Beyond BRCA Mutations May Lead to Homologous Recombination Deficiency
Data from Cancer Genome Atlas (TCGA) demonstrates that approximately 50%
of high grade serous ovarian cancers have aberrations in HR repair
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Differences between patients with BRCA1/BRCA2-mutated tumors and
sporadic tumors
Davies Nat Med 2017
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Copy number signatures in HGSOC
Macintyre Nat Genetics 2018
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Mi-OncoSeq
Michigan Oncology Sequencing ProgramPresented By Erin Cobain at 2017 ASCO Annual Meeting
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Mi-OncoSeq
MET500 DemographicsPresented By Erin Cobain at 2017 ASCO Annual Meeting
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Mi-OncoSeq
Presented By Erin Cobain at 2017 ASCO Annual Meeting
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Mi-OncoSeq: Case Example #2
Presented By Erin Cobain at 2017 ASCO Annual Meeting
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Patient survival and response to pembrolizumabacross 12 different tumor types with mismatch
repair deficiency
Le Science 2017
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#-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
Infantile fibrosarcoma
Soft tissue sarcoma
Thyroid
Salivary gland
Melanoma
Breast
Lung
Appendix
Gastrointestinal stromal tumour
Colon
Pancreas
Cholangiocarcinoma
Larotrectinib - Efficacy Across Tumour Types – Integrated Data Set
Congenital mesoblastic nephroma
Unknown primary
Bone sarcoma
93.2
#
*
Max
imum
cha
nge
in tu
mou
rsi
ze (
%)
‡Includes 9 unconfirmed PRs pending confirmation; does not include 13 patients continuing on study and awaiting initial response
assessment *Patient had TRKC solvent front resistance mutation (G623R) at baseline due to prior therapy; #Surgical CR; †RECIST
1.1. Note: Two patients not shown here. These patients discontinued treatment prior to any post-baseline tumour measurements
CR, complete response; ORR, objective response rate; PR, partial response.
1. Lassen UN, et al. Presented at: ESMO 2018 Congress; October 19-23, 2018; Munich, Germany. Abstract 4090
Investigator response assessments, as of 30 July 2018
Integrated‡
(n=109)
ORR (95% CI)† 81% (72‒88%)
Best response†
PR 63%
CR 17%
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26
There appears to be significant correlation between TMB and patient response to anti–PD-L1/PD-1 therapy
Significant correlation (P
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The major classes of genomic alterations that give rise to cancer
Modified from McConaill JCO 2010
EGFRBRAFKRASNRASBRCA1/2ERBB2PIK3CAAKT1MAP2K1STK11FGFR1-3IDH1
EML4-ALKROS-1RETNTRK1-2-3FGFR1-2-3
ERBB2EGFRMET
Sequencing,qPCR,NGS etc.
FISH, ImmunohistochemistryqPCR, NGS
MSIMET ex14 skippingTMB
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DCA N. 89 del 05/11/2018
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Rete regionale della oncogenetica
• Identificare i bisogni della popolazione della regione Campania con riferimento alla problematica delle neoplasie ereditarie
• Stabilire i percorsi per il counseling genetico ed i test di laboratorio, definendo le modalità di interazione tra oncologo, genetista e laboratorio di biologia molecolare
• Organizzare una rete laboratoristica regionale che condivida metodologie di analisi e di interpretazione e schemi di refertazione
• Definire programmi di sorveglianza sanitaria per i soggetti ad alto rischio, portatori di alterazioni genetiche predisponenti al cancro
• Garantire la massima integrazione tra tutte le professionalità coinvolte nella gestione dei soggetti a rischio e nel trattamento di pazienti con neoplasie legate ad alterazioni genetiche
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Genomics-Driven Oncology
Garraway JCO 2013
SurgeonEndoscopistRadiologist
SurgeonEndoscopistRadiologist
MedicalOncologist
MedicalOncologist
Pathologist, Molecular Biologist, Geneticist
MedicalOncologist
Surge
on
Rad
ioth
erap
ist