Plasma based biomarkers in

advanced prostate cancer

Gerhardt Attard MD MRCP PhD

Cancer Research UK Clinician Scientist and

Consultant Medical Oncologist

Treatment Resistance Group, Centre for Evolution and Cancer

The Institute of Cancer Research and

the Royal Marsden NHS Foundation Trust

Disclosures relevant to presentation

• Employee of the Institute of Cancer Research (ICR) that has

a commercial interest in abiraterone. I’m on The ICR

rewards to inventors list of abiraterone.

• PI for trials sponsored by Janssen, Medivation, Astellas,

Arno.

• Received:-

– Consulting fees and travel support from Janssen,

Astellas, Medivation, Essa, Arno, Sanofi.

– Speaker’s fees from Janssen, Astellas and Sanofi.

– Grant support from Janssen, AstraZeneca, Arno, Innocrin.

Plasma DNA studies in CRPC

• Cell-free DNA is invariably

present in plasma

• ctDNA (tumor) can constitute

<1% to >90% of total cfDNA

• Amenable to repeated and

real-time sampling

• Different processing required

for mRNA (eg AR-V7)

Clinical implementation of plasma DNA

In January 2015, the EMA extended the label of erlotinib to

include patients with detection of EGFR mutations in plasma DNA

Wan et al. Nat. Rev. Cancer 2017

Liquid biopsies in APC

Data shows strong associations with outcome in a

range of contexts,

but no evidence that patient outcome will be

improved or not harmed by using a liquid biopsy

test to choose treatment

Is the absence of data a justification for the use of

potentially inaccurate information?

Liquid biopsies in APC

Data shows strong associations with outcome in a

range of contexts,

but no evidence that patient outcome will be

improved or not harmed by using a liquid biopsy

test to choose treatment.

Is the absence of data a justification for the use of

potentially inaccurate information?

Or can we reach a consensus that liquid biopsy

tests should not be used to select patient treatment

outside the setting of a clinical trial?

Tu

mo

ur

Vo

lum

e a

nd

Ac

tivit

y

Local

therap

y

LHRH

analogue +/-

docetaxel

Abiraterone and

prednisolone/

Enzalutamide

Docetaxel

chemotherapy

Cabazitaxel

second line

chemotherapy

and/or trials

Castrate Sensitive Castrate Resistant Disease

Time

Management decision points in APC

Treatment

selection

Response

assessment

Biomarkers of response (eg. DNA repair defects)

Biomarkers of resistance (AR gene aberrations)

Change in plasma tumour DNA fraction

Genotype emergence of resistant clones

Quantitation of plasma tumour DNA fraction

Variable fraction of

normal DNA mixed with

DNA from multiple

heterogeneous tumour

clones

Accurate quantitation

of tumour DNA fraction

needed for:

Genotyping resistant

clones

Estimations of CNA

Treatment monitoring

Prognostication

Carreira, Romanel et al, Sci. Transl. Med. 2014; 254ra125

Tracking somatic CNA in plasma

Ulz et al, Nat. Commun. 2016, 22;7:12008

• Shallow Whole Genome Sequencing

• Can inform on ctDNA fraction

• Sensitivity dependent on magnitude of CNAs

• 60-80£/sample; 72 hours – 2 week turn around

• New focal AR amplification at progression on castration

High-sensitivity assessment of plasma

tumour DNA – how broad a panel?

• High-depth targeted NGS to

detect prostate cancer genomic

aberrations

• ?Clones can emerge that do

not harbour selected lesions?

• CtDNA fraction = abundance

of the most abundant lesion

• Quantitation using 3 common

aberrations shows high

correlation with WES

• 250-300£/test

• 10 days - 3 weeks

Francesca Demichelis

Alessandro Romanel

Circulating tumour DNA in mCRPC

Median ctDNA fraction = 0.181

• Targeted NGS of common genomic lesions in prostate cancer

identifies tumor DNA in plasma from ALL progressing CRPC pts

Romanel, Gasi Tandefelt et al. Sci Transl Med

2015, 312re10

N=80

21q

del

8p

del

Plasma tumour DNA appears to track

response and progression on treatment

Most abundant

Undetectable

Detectable but at

lower abundance

Carreira, Romanel et al, Sci. Transl. Med. 2014; 254ra125

Tu

mo

ur

Vo

lum

e a

nd

Ac

tivit

y

Local

therap

y

LHRH

analogue +/-

docetaxel

Abiraterone and

prednisolone/

Enzalutamide

Docetaxel

chemotherapy

Cabazitaxel

second line

chemotherapy

and/or trials

Castrate Sensitive Castrate Resistant Disease

Time

Management decision points in APC

Treatment

selection

Response

assessment

Biomarkers of response (eg. DNA repair defects)

Biomarkers of resistance (AR gene aberrations)

Change in plasma tumour DNA fraction

Genotype emergence of resistant

clones

Days

Treatment resistance on abiraterone

associates with AR 2105T>A (p.L702H)

Carreira, Romanel, Goodall et al,

Sci. Transl. Med. 2014; 254ra125

Tracking evolution to treatment resistance

In ~15%, L702H or T878A show a temporal relationship with progression

N=44 treated with abiraterone

Romanel, Gasi Tandefelt et al. Sci Transl Med 2015, 312re10

Plasma AR associates with resistance

to abiraterone

N=80; plasma within 30 days of starting abiraterone Romanel, Gasi Tandefelt et al. Sci Transl Med 2015, 312re10

Tu

mo

ur

Vo

lum

e a

nd

Ac

tivit

y

Local

therap

y

LHRH

analogue +/-

docetaxel

Abiraterone and

prednisolone/

Enzalutamide

Docetaxel

chemotherapy

Cabazitaxel

second line

chemotherapy

and/or trials

Castrate Sensitive Castrate Resistant Disease

Time

Management decision points in APC

Treatment

selection

Response

assessment

Biomarkers of response (eg. DNA repair defects)

Biomarkers of resistance (AR gene aberrations)

Change in plasma tumour DNA fraction

Genotype emergence of resistant clones

Clinically-informative profiling of plasma DNA

Wyatt et al, JAMA Onc 2016

Loss of heterozygosity in DNA repair

genes in plasma DNA

Annala et al, Eur Urol 2017

Detection of deletion of the somatic allele in ctDNA from

patients with a germline mutation in DNA repair genes

Opportunity for treatment selection

Droplet digital PCR for determining AR status

• Multiplex droplet digital PCR – 4 reference genes

• 50£ per sample. Result within one day.

• High inter-lab reproducibility (r=0.96)

• High agreement with NGS for AR copy number and mutations

• AR gain in 14-34%

• AR mut in 2-30% Daniel Wetterskog, Cinzia Conteduca, Ugo de Giorgi

Plasma AR status and outcome on

abiraterone/enzalutamide

N=171 Interaction between AR and chemotherapy status (P=0.83 for OS, P=0.99 for PFS)

Qualification of plasma AR in PREMIERE trial

PREMIERE team:

Enrique Grande

María Piedad Fernández Pérez

Albert Font

Sergio Vázquez Estévez

Aránzazu González del Alba

Begoña Mellado

Ovidio Fernández Calvo

María José Méndez-Vidal

Miguel Angel Climent

Ignacio Duran

Enrique Gallardo

Angel Rodríguez

Carmen Santander

M Isabel Sáez

Javier Puente

Teresa Alonso

Julián Tudela

Alberto Martínez

Daniel Castellano

Enrique González Billalabeita

• Biomarker trial

• 98 mCRPC (PREVAIL criteria) treated

with enzalutamide in 16 Spanish

hospitals

• Plasma collected pre-treatment from 94

• Sponsored and conducted by the

Spanish

Genito-Urinary oncology Group (SOGUG)

• Support from Astellas

• Designed to analyze the predictive value

of TMPRSS2-ETS

• Included exploratory analyses of

associations with outcome for AR-V7

detected in CTCs* and plasma AR

*Grande E, Ann Oncol 2016;

27(Suppl 6): vi243-vi265

Plasma AR is associated with worse

outcome in PREMIERE trial

N=94

Future directions

• Collection of plasma in prospective trials

• Prospective trials to clinically qualify

associations with outcome

• Trials evaluating plasma DNA based treatment

selection

• Robust, analytically validated APC-specific NGS

assays

• Composite assays that include mRNA analysis

Future directions

• Collection of plasma in prospective trials

• Prospective trials to clinically qualify

associations with outcome

• Trials evaluating plasma DNA based treatment

selection

• Robust, analytically validated APC-specific NGS

assays

• Composite assays that include mRNA analysis –

overlap between AR CN and AR-V7

G Attard,

Marsden

K Chi,

Vancouver

M Rubin,

Cornell

F Demichelis,

Trento

E Van Allen,

DFCI C Maher,

Wash U

H Beltran,

Cornell

A Wyatt,

Vancouver A Armstrong,

Duke

PCF SELECT (Specific Evaluation in Liquid

biopsies of Established prostate Cancer Targets)

plasma DNA assay

To accelerate the development and achieve the implementation of a plasma DNA test for metastatic prostate cancer into widespread clinical practice within 5 years

• We recognize that each of our institutions is capable of establishing our own ctDNA assay for prostate cancer.

• However, by working together as a team we are best positioned to gain the widest acceptance for a community-relevant assay for advanced prostate cancer.

@PCF_SELECT

Aim 1: To design a prostate-cancer specific,

clinically-applicable targeted NGS panel optimised

for treatment selection and response surrogacy in

metastatic prostate cancer.

Aim 2: To develop and optimize the assay in a

central CLIA/CLEP approved molecular genomics

laboratory based on the consortium specifications.

Aim 3: To implement the assay at consortium sites

and collaborators to obtain stage 1 clinical

qualification in a range of scenarios and

interrogate biological and biomarker questions

@PCF_SELECT

Conclusions

• Using high-coverage NGS, circulating tumor DNA is

detected in plasma from all progressing mCRPC patients

• Plasma DNA is representative of clinically relevant

progressing metastases

• Plasma DNA could be used to select targeted treatment –

challenge of ctDNA fraction.

• Plasma AR copy number gain or mutations strongly

associate with worse outcome on abiraterone or

enzalutamide in both chemo-naïve and post-docetaxel

mCRPC

• Prospective evaluation of plasma-based treatment

decisions is now warranted and required to confirm clinical

utility