La biologia dei meccanismi di riparo del DNA...Mechanisms of double-strand DNA breaks repair • Homologous recombination (HR): provides accurate recombination using a sister chromatid

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

An overview of types of DNA damage and causal agents

Helleday Nat Rev Genetics 2014

How the cell copes with damaged DNA

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


• Nucleic acid excision repair (NER): removes short single-stranded DNA segment around the lesion and repairs mutations resulting from UV light and hydrocarbons



• Mismatch repair (MMR): recognizes and corrects mismatched bases that can result from DNA replication and recombination


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


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

Homologous recombination (HR)

Toss & Cortesi J Cancer Sci Ther 2013

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

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

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

DNA

damage

PARP

Formation of single

strand DNA break

(SSB)

Repair of of SSB by


PARP inhibition Impairs base excision repairSSB persists




(2010)


DNA

damage

PARP

Formation of single

strand DNA break

(SSB)

Repair of of SSB by



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




(2010)


DNA

damage

PARP

Formation of single

strand DNA break

(SSB)

Repair of of SSB by



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




(2010)


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…

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

Differences between patients with BRCA1/BRCA2-mutated tumors and

sporadic tumors

Davies Nat Med 2017

Copy number signatures in HGSOC

Macintyre Nat Genetics 2018

Mi-OncoSeq
Michigan Oncology Sequencing Program

Presented By Erin Cobain at 2017 ASCO Annual Meeting

Mi-OncoSeq
MET500 Demographics


Mi-OncoSeq


Mi-OncoSeq: Case Example #2


Patient survival and response to pembrolizumabacross 12 different tumor types with mismatch

repair deficiency

Le Science 2017

#-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%

26

There appears to be significant correlation between TMB and patient response to anti–PD-L1/PD-1 therapy

Significant correlation (P

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

DCA N. 89 del 05/11/2018

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

Genomics-Driven Oncology

Garraway JCO 2013

SurgeonEndoscopistRadiologist

SurgeonEndoscopistRadiologist

MedicalOncologist

MedicalOncologist

Pathologist, Molecular Biologist, Geneticist

MedicalOncologist

Surge

on

Rad

ioth

erap

ist

Documents

La biologia dei meccanismi di riparo del DNA...Mechanisms of double-strand DNA breaks repair • Homologous recombination (HR): provides accurate recombination using a sister chromatid