delivering on the 
rnai promise
silence therapeutics plc  
annual report and accounts 2011
silence therapeutics plc annual report and accounts 2011 silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
highlights of 2011
operational
 i impressive interim data from phase i trials of atu027 our lead 
programme in metastatic cancer were presented at the prestigious american 
society of clinical oncology conference in june 2011 the data showed disease 
stabilisation and other indications of potential efficacy atu027 remains one of 
the most advanced rnai therapeutics candidates in cancer
 i silence’s leadership position in rnai delivery validated by three 
new partnerships including deals with a top ten pharmaceutical company 
interna technologies and mirna therapeutics these agreements covered 
all three of our proprietary delivery technologies and two were for the delivery of 
a new form of rna therapeutic microrna showing the versatility of our portfolio 
 i positive clinical data from our partners quark pharmaceuticals and pfizer 
announced that their phase ii trial of pf04523655 in diabetic macular oedema 
showed it to be more effective than laser therapy quark has now initiated 
a phase iib trial this compound is based on silence’s aturnai technology 
 i silence streamlined and reorganised its operations to increase 
efficiency and reduce cash spend as part of this the facility in redwood city 
california was closed in addition headcount in some noncritical roles was 
reduced in berlin and the nonexecutive board membership reduced 
 i enhanced commercial focus and strengthened business development team 
at silence with the appointment of georg buchner as vp business development 
focused on partnering our assets and accessing nondilutive sources of finance
 i silence possesses one of the world’s most comprehensive rnai 
intellectual property portfolios which was further strengthened in 2011 
with the issuance of patents in japan and the us 
 i in may 2011 silence raised £551m net of expenses to fund the 
development of the pipeline and investment in the rnai technology platform 
combined with the impact of the restructuring the cash runway extends to 
the end of q3 2012
post year end events
 i dr tony sedgwick was promoted to chief executive officer 
in february 2012 
 i deal announced with miragen therapeutics in january 2012 for the 
delivery of micrornas using the dbtc liver delivery system silence’s second deal 
on dbtc and third for micrornas
 i creation of a scientific advisory board with two key opinion leaders 
in the area of liver disease
financial
financial statements
22 independent auditors’ report
23 consolidated income statement
23 consolidated statement of comprehensive income
24 consolidated balance sheet
25  consolidated statement of changes in equity
26 company balance sheet
27  company statement of changes in equity
28 cash flow statements
30 notes to the financial statements
ibc  company information and advisers
business review
ifc highlights of 2011
01 about us
02 our process
03 chairman’s statement 
05 our progress
06  chief executive’s review
13 financial review
corporate governance
14 board of directors
16 directors’ report
visit us online at 
wwwsilencetherapeuticscom
revenue
2010 £237m
£069m
administrative expenses
2010 £520m
£312m
cash position at year end
2010 £357m
£369m
research and development costs 
2010 £582m
£336m silence therapeutics plc annual report and accounts 201 1 business review · 01
silence therapeutics is a global leader in 
the discovery development and delivery of 
novel rnai therapeutics for the treatment 
of serious diseases
rna interference a nobel prize winning technology 
is one of the most exciting areas of drug discovery today
  to find out more about how rnai therapeutics work  
visit wwwsilencetherapeuticscom
partnerships with nine  
other companies
silence’s rnai therapeutic platform has received key 
validation through multiple partnerships with several 
major pharmaceutical companies
read more
turn to page 2
our 
process
an impressive pipeline  
of products
silence has successfully progressed the development 
of its proprietary drug candidates and built further 
foundations to support the company’s future growth
read more
turn to page 5
our 
progress
             multiple partnerships
highvalue partnered and internal pipeline
corporate and 
shareholder value
silence now possesses one of the most comprehensive platforms 
in rnai therapeutic development spanning delivery sequences 
and structural features we are executing a twopronged strategy 
to best leverage this platform and our development expertise 
towards the creation of corporate and shareholder value
leveraging our broad rnai platform
about us 02 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
2006
2007
2008
2009
 
 2010
2011
a key component of silence’s business strategy is the 
establishment of additional high‑value partnerships with 
the leading pharmaceutical and bio technology companies
kyowa hakko kirin licence from 
dicerna pharmaceuticals inc 
novartis option  licence of qpi1002 
from quark
us department of defense deal with 
tekmira corp for ebola treatment
mirna therapeutics licencing deal 
with marina biotech inc
more than 26 rnai‑related transactions 
with total value of more than 24bn have 
been completed since january 2010
14bn
680m
140m
63m
we are actively pursuing the establishment of 
additional partnerships with pharmaceutical 
and bio technology companies
during 2011 silence announced that it 
had entered into an agreement with interna 
technologies bv mirna therapeutics inc and 
a top ten pharmaceutical company
partnership landscape
pfizerquark
top 10 pharma
astrazeneca
dainippon sumitomo
novartisquark
our process
pfizerquark
aturnai for diabetic macular edema and 
agerelated macular degeneration 95m in 
milestones plus royalties now in ph ii
astrazeneca
research collaboration 15m upfront 
and 400m in milestones plus royalties 
for 5 targets
astrazeneca
novel approaches to delivery 
of sirna molecules
dainippon sumitomo pharma
sirna delivery collaboration
astrazeneca
extension of both collaborations
interna 
technologies
delivery 
collaboration on 
atuplex
dainippon sumitomo 
pharma
expansion of delivery 
collaboration
novartis
option  licence agreement 
with quark 82m in 
milestones plus royalties
mirna therapeutics
delivery collaboration on atuplex 
 dbtc
top 10 pharma
delivery collaboration 
on dacc
our partnerships to date
mirna
interrna
wwwsilencetherapeuticscom 02 · silence therapeutics plc annual report and accounts 201 1 silence therapeutics plc annual report and accounts 201 1 business review · 03
chairman’s statement
“ our strong portfolio of intellectual property and delivery technologies 
makes us a partner of choice for companies active in rna therapeutics”
silence therapeutics is a leading rnai 
therapeutics product and technology 
platform company with proprietary 
delivery systems we have created two 
powerful platforms and a strong pipeline 
to exploit our impressive technological 
know‑how and ip
despite the difficult economic times and capital market 
turmoil with your support in 2011 we were able to announce 
positive progress in our internal clinical programme refinance 
and streamline the business as well as sign further collaborative 
agreements covering our rnai delivery technologies 
we believe that our achievements throughout the year 
validate the board’s decision to focus on building an 
independent and high value rnai therapeutics company 
indeed industry commentators believe that the field of 
oligonucleotide therapeutics of which rnai is a part 
may be the third major drug development platform after 
small molecules and monoclonal antibodies 
when we reported to you in our 2010 annual report 
we predicted that 2011 would be a year rich in data from 
rnai clinical trials both from silence therapeutics and 
other companies in this therapeutic area this has proved 
to be the case with encouraging interim phase i data from 
our lead product atu027 for metastatic cancer which we 
were pleased to be able to present at the prestigious annual 
american society of clinical oncology ‘asco’ meeting in 
june 2011 we believe it to be one of the most interesting and 
potentially promising rnai therapeutics in clinical development 
during the year our partner quark pharmaceuticals also 
presented positive phase ii data with pf‑04523655 which 
incorporates our aturnai technology in the area of diabetic 
macular oedema 
silence therapeutics’ rnai therapeutic platform comprising 
our delivery technologies sirna sequences and structural 
features has been validated by nine partnerships some of 
these via our licensee quark pharmaceuticals in 2011 alone 
we were pleased to add three new deals including delivery 
deals with interna technologies mirna therapeutics and 
a top ten pharmaceutical company as a result we now have 
links to four of the world’s leading pharmaceutical firms 
assuming these collaborations continue to proceed successfully 
we believe that associated milestone payments represent 
a significant potential revenue stream to silence therapeutics 
in the coming years 
other achievements for silence therapeutics in 2011 included 
a fundraising which has extended existing funding until the 
end of the third quarter of 2012 streamlining of the business 
and a significant strengthening of the business development 
and management team the latter two we believe represent 
an appropriate response to our developing pipeline expanding 
portfolio of high‑quality delivery technologies and re‑focused 
business approach assuming that our pipeline continues to 
progress silence will be seeking deals with partners to further 
its development in addition we believe that our strong portfolio 
of intellectual property and delivery technologies makes us 
a partner of choice for companies active in rna therapeutics 
and we will continue to build this important non‑dilutive 
source of income as with many other approaches in the 
medical field delivery of the active rnai therapeutic is the 
rate‑limiting step and so we consider our suite of delivery 
technologies an important asset for us and our partners 
the evolution of the company since the beginning of 2011 has 
resulted in some personnel changes with dr tony sedgwick 
recently appointed chief executive officer and dr georg 
buchner joining as vice‑president of business development 
on behalf of the board i would like to thank dr phil haworth 
dr david u’prichard and dr james topper all of whom stood 
down during or at the end of 2011 for their contributions to 
the company as chief executive officer and non‑executive 
directors respectively david u’prichard in particular has been 
with the business for almost eight years our thanks are also 
due to thomas christély who initially replaced dr phil haworth 
and has recently left the company to be succeeded by our 
new and commercially driven chief executive officer 
dr tony sedgwick tony comes with a strong background 
in the commercial biotech environment and has been 
successfully involved in developing biotech businesses 
and delivering value to shareholders 
jerry randall aca chairman wwwsilencetherapeuticscom 04 · silence therapeutics plc annual report and accounts 201 1
clinical data emphasises potential  
of rnai therapeutics
with five of the estimated 13 clinical programmes ongoing 
worldwide using silence therapeutics’ aturnai technology 
and having treated in excess of 300 patients we believe we 
have the industry’s broadest sirna clinical pipeline looking 
elsewhere in the rnai sector in 2011 we were pleased to 
observe encouraging clinical data from other players which 
underlines the potential of the approach many of those 
working in this field share our view that the range of clinical 
results announced in 2011 represent a significant derisking 
of rnai technology and we look forward to further clinical 
advances in 2012 
the significant progress that silence therapeutics made 
in 2011 was achieved against a backdrop of a restructuring 
and consolidating pharmaceutical sector restricted access 
to capital for small and innovative companies and turbulent 
risk‑averse financial markets that we were able to raise 
£551m net of costs under these conditions is a testament 
to the potential of the company and the confidence placed 
in us by our shareholders and many thanks are due to you 
for this i am as disappointed as you are that our increasing 
maturity is not yet reflected in silence therapeutics’ share 
price and believe that our new focused approach coupled 
with the newsflow and advances we expect to announce 
in 2012 will go a considerable way to building shareholder 
value and enhancing our share price 
at silence therapeutics the directors consider our key 
performance indicators ‘kpis’ an important way for us and 
you to monitor our progress our financial and non‑financial 
kpis are listed below and are we believe appropriate for 
a biotechnology company at this stage of development 
kpis at silence therapeutics
financial kpis
 i cash position in relation to cash flows
 i expenditure on research and development activities
non‑financial kpis
 i number of drugs in development by stage of development
 i number of pharmaceutical collaborations 
 i development milestones reached
 i signature of research collaborations and licences to bring 
in both development partners and revenue
the performance of silence therapeutics versus these kpis 
is discussed in my report as well as in the chief executive’s 
statement on pages 6 to 12 and the financial review on 
page 13 since there are a number of potential risks and 
uncertainties that could have a material impact on the group’s 
performance – including clinical and regulatory risk competition 
and intellectual property risk and economic financial and 
counterparty risk – i should also draw your attention to the 
directors’ statement on these matters on pages 14 to 21 
silence therapeutics is proud of its rnai therapeutic platform 
comprising proprietary delivery technologies potent sirna 
sequences and innovative rnai structural features we believe 
that our progress in 2011 shows the synergistic value of these 
assets and we look forward to updating you on further advances 
in the clinic and other areas delivered via our new and focused 
management team throughout 2012 
thank you for your continued support of silence therapeutics
jerry randall aca
chairman 
27 march 2012
chairman’s statement continued
“ we believe we have the industry’s broadest sirna clinical pipeline 
and we look forward to further clinical advances in 2012” silence therapeutics plc annual report and accounts 201 1 business review · 05
silence is a leader in the development of clinical‑stage 
rnai therapeutics having developed a broad pipeline 
of internal and partnered product candidates
almost half of the sirna programmes currently in clinical 
trials are based on silence’s technology
sirna delivery 
technologies and ip
highvalue sirna 
sequences and ip
nextgen structural 
features and ip
delivery from sequence to clinic
silence’s expertise encompasses rnai structural  
chemistry and drug delivery as well as preclinical  
and clinical development
silence holds a powerful and strategic position in  
each of the three areas critical to building protecting  
and commercialising rnai therapeutics
i proprietary delivery technologies
i potent sirna sequences and
i innovative sirna structural features
our progress in 2011
to read more 
about our pipeline  
turn to page 9
2011 2012
delivery collaboration  
on atuplex
delivery collaboration on 
atuplex  dbtc
delivery collaboration  
on dacc 
delivery collaboration  
on dbtc
top 10 pharma
deals since 2011
silence has announced four deals since january 2011 to leverage its growing portfolio of rnai delivery 
capabilities particularly in the area of micrornas 06 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
overview
since joining silence therapeutics in september 2011 
i have been excited by the company and the opportunities 
that lie ahead as a consequence i was pleased to take over 
as chief executive officer in february 2012 as i believe 
we have a unique proprietary position in rnai therapeutics 
and their delivery over the next few years i intend to increase 
the commercial focus of the company harness the rnai 
therapeutics opportunity and as a result create substantial 
shareholder value
2011 has been an exciting year for silence therapeutics 
with progress across all areas of the business we started 
this year looking forward to clinical data to validate both 
the therapeutic benefit to be obtained by rna interference 
rnai or sirna as well as our proprietary delivery 
technologies i am pleased to report that our company 
has delivered on this expectation in both our proprietary 
and partnered programmes 
we have also worked hard on building the financial future 
of the business improving its efficiency and strengthening 
its commercial activities all of which is discussed below 
silence therapeutics is proud of its rnai therapeutic 
platform comprising proprietary delivery technologies 
potent sirna sequences and innovative rnai structural 
features we believe that our progress in 2011 shows the 
synergistic value of these propositions 
encouraging clinical data
silence therapeutics is prominent in an exciting new sector 
in the drug development arena the translation of rna blocking 
rnai technology into therapies since we and others active 
in this area believe that the technology has potential in a broad 
range of clinical indications – including oncology vascular 
metabolic and ophthalmic diseases – it brings the potential 
for better patient outcomes in these major therapeutic areas 
one of the first steps in demonstrating this potential is the 
generation of data from clinical studies conducted with 
rnai therapeutics
in june 2011 silence presented encouraging interim data 
from its ongoing phase i trial of proprietary product atu027 
in patients with solid tumours at the prestigious annual meeting 
of the american society of clinical oncology asco 
we believe that these important findings serve as valuable 
validation for silence’s rnai technology platform as well 
as its atuplex™ delivery technology this should stand the 
company with its increased business development focus 
in good stead as we work on partnering our programmes 
and exploiting our valuable rnai delivery intellectual 
property estate 
to summarise silence therapeutics made progress in several 
key areas in 2011 which we discuss in more detail below 
these include
 i clinical trial progress for both our proprietary and 
partnered programmes
 i three new delivery deals with further progress 
in established programmes
 i sharpening of our business development focus 
with important new top‑level hires
 i refinancing and restructuring of the organisation and
 i further development and recognition of silence’s 
intellectual property portfolio particularly in the area 
of rnai delivery
operational
clinical trial progress for both our proprietary 
and partnered programmes
clinical trial data is key to establishing the potential of rnai 
therapeutics and we are pleased that it generated significant 
excitement this year both for silence and its partners 
proprietary programmes
atu027 silence therapeutics’ lead programme for cancer
in 2011 we were able to report impressive interim results 
from the phase i ascending dose clinical trial of our lead 
programme cancer treatment atu027 for solid tumours 
atu027 incorporates our atuplex delivery system with 
aturnai our proprietary rnai chemistry and specifically 
targets pkn3 a protein implicated in cancer growth 
and metastases
these results were presented at asco and showed stabilisation 
of the disease in 38 of the cases 9 of 24 patients as well 
tony sedgwick chief executive officer
chief executive’s review
“ wehaveworkedhardonbuildingthefinancialfutureofthebusiness
improvingitsefficiencyandstrengtheningitscommercialactivities” silence therapeutics plc annual report and accounts 201 1 business review · 07
as other indications of potential efficacy importantly on 
the safety side the trial data obtained so far have indicated 
that atuplex is safe in humans at dose levels above those 
that have shown effectiveness in preclinical studies among 
the patients who achieved stable disease one individual with 
neuroendocrine cancer achieved disease stabilisation for 
nine months with a second neuroendocrine cancer patient 
showing partial regression of pulmonary metastases 
an additional patient with breast cancer experienced 
some regression in liver metastases 
32 patients have been treated so far and enrolment of all 
33–36 patients is expected to be completed in the first half 
of 2012 with results announced in the middle of the year 
the company believes that the encouraging data 
received to date represents an important step along the 
path towards realising value for shareholders assuming 
successful completion of the phase i study we expect to initiate 
a phase ibiia clinical study of atu027 in the second half of 
2012 the company will also continue licensing discussions 
regarding atu027 with potential pharmaceutical partners 
atu111 our most advanced product outside oncology
atu111 for the treatment of acute lung injury is our most 
advanced drug development candidate outside oncology 
it combines our dacc drug delivery system with aturnai 
and its target is undisclosed we have recently completed 
proof of concept studies in a preclinical model of acute lung 
injury demonstrating very impressive results using atu111 
further studies are ongoing in a variety of other preclinical 
models of the disease 
earlier preclinical work using atu111 has shown sustained 
gene knockdown of up to three weeks in the lung endothelium 
suggesting the drug could be used with a single dose 
atu134
following the encouraging data generated from the ongoing 
phase i trial of atu027 and additional data from preclinical 
models of atu134 silence has concluded that the potential 
clinical profiles of these two products are too similar to 
warrant further development of both programmes we 
therefore decided in november to divert the resources for 
atu134 to other areas specifically potential targets in the liver 
that could be inhibited by using silence’s novel liver‑focused 
dbtc delivery system 
partnered programmes
silence therapeutics has two licence agreements with partner 
quark pharmaceuticals for products pf‑04523655 and 
qpi‑1002 both of which are in development in two different 
therapeutic indications quark has licensed these to pfizer 
and novartis respectively the positive data received from 
the programmes in 2011 further highlights both the potential 
of rnai therapeutics and of silence’s aturnai technology 
which is incorporated into these products
q u a r k  p fi z e rp r o g r a m m e s
in march 2011 quark announced the completion of the degas 
study a phase ii clinical trial of pf‑04523655 for the treatment 
of the ophthalmic indication of diabetic macular oedema 
the product which incorporates silence’s aturnai technology 
was shown to be more effective than laser therapy quark 
has now initiated a phase iib study comparing pf‑04523655 
to lucentis rochenovartis the new standard of care in the 
treatment of diabetic macular oedema 
in addition pf‑04523655 recently completed a phase ii trial 
in the second ophthalmic indication of age related macular 
degeneration the trial demonstrated a dose‑dependent increase 
in benefit of pf‑04523655 quark is now awaiting results from 
the phase iib trial in diabetic macular oedema before deciding 
on plans for the drug in age‑related macular degeneration
quarknovartis programmes
in august 2010 quark signed an option and licence agreement 
with novartis for qpi‑1002 as mentioned previously in september 
of that year quark initiated a phase ii study in prevention 
of delayed graft function in patients undergoing kidney 
transplantation recruitment into this trial has progressed 
well and we expect the trial to be completed in the middle 
of 2012 a phase i study has been successfully completed 
in the second indication of acute kidney injury quark plans 
to initiate a phase ii trial depending on the results of the 
ongoing trial in the prevention of delayed graft function 
summary
 i silence therapeutics is a leader in an exciting new drug 
development arena known as rnai
 i silence made significant progress in 201 1 with its internal pipeline 
in particular interim phase i data of lead programme atu027 was 
presented in june at the prestigious annual meeting of the 
american society of clinical oncology asco 
 i silence’s partnered programmes made significant advances during 
2011 with pf04523655 quarkpfizer successfully completing a 
phase ii trial in diabetic macular oedema and qpi1002 progressing 
well in a phase ii trial in prevention of delayed graft function
 i the value of this portfolio of delivery technologies was underlined 
in 201 1 with the signature of three agreements with new partners 
interna technologies bv mirna therapeutics inc and a top ten 
pharmaceutical company
 i silence therapeutics has two licence agreements with 
partner quark pharmaceuticals for products pf 04523655 
and qpi 1002 both of which are in development in two 
different therapeutic indications
 i efficient and safe delivery of rnai therapeutics is key to the 
success of the field and silence now has three such delivery 
systems atuplex dacc and dbtc 08 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
progress in research collaborations
silence is pleased to have been working with astrazeneca 
in the area of rnai since 2007  in the form of two collaborations 
both of which were extended in 2010 astrazeneca has now 
completed the research phase of the first of these collaborations 
a research and development collaboration focused on five 
respiratory and oncology targets and nominated three of 
the five targets as “accepted programmes” 
the second collaboration for the development of novel 
approaches for the delivery of sirna molecules was 
entered into in march 2008 the research phase of this 
collaboration has also been completed and astrazeneca 
retains the right to use the dacc delivery system developed 
for their “accepted programmes”
valuable portfolio of delivery technologies
efficient and safe delivery of rnai therapeutics is key to the 
success of the field and silence therapeutics’ programmes 
as well as those of other companies active in this area 
the company possesses three proprietary sirna delivery 
technology platforms atuplex dacc lung and dbtc liver 
two of which are already being used in the programmes of 
partners this comprehensive delivery platform allows our rnai 
therapeutics to reach many different organs with the liver and 
lungs increasingly becoming targets of interest in the rnai field 
and the pharmaceutical industry generally 
because of the importance of appropriate delivery in 
this therapeutic area we believe our delivery platform will 
deliver significant value to the company via non‑exclusive 
partnership deals 
 i atuplex enables the delivery of sirna molecules to targeted 
diseased tissues and cells in the vascular endothelium blood 
vessels while increasing their bioavailability and intracellular 
uptake it incorporates silence’s proprietary lipid atufect and 
is used to embed sirnas into a multiple lipid bi‑layer 
structure it is incorporated in atu027 
 i the dacc novel lipid delivery system enables functional 
highly specific and efficient delivery of sirna molecules 
selectively to the lung endothelium with a long duration of 
action over three weeks like atuplex it also incorporates 
silence’s proprietary lipid atufect and is used to embed 
sirnas into a multiple lipid bi‑layer structure the dacc 
delivery system is incorporated in atu111 silence’s preclinical 
development candidate for the treatment of acute lung injury
 i the dbtc delivery system is lipid‑based and targets the 
liver studies have shown it to be well tolerated and have 
a significant duration of action it therefore has therapeutic 
potential in areas such as heptatocellular carcinoma liver 
fibrosis and acute liver failure 
chief executive’s review continued
“ the value of our portfolio of delivery technologies was underlined 
in 2011 with the signature of three agreements with new partners”
goal review
last year we set ourselves some goals for completion 
at the end of 2011
1  complete phase i clinical 
trial of atu027
completion is now expected in the middle of 2012
2  present interim phase i 
data on atu027
data was presented at the american society 
of clinical oncology asco
3   ad v a n c e p r e c li n i c a l 
programmes for atu134 
and atu111
atu111 continues to progress through preclinical 
development however in november 2011 the 
decision was taken to refocus resources away 
from atu134
4   c o m p l et e n e w 
corporate alliances
during 2011 silence signed three new collaborations 
relating to its rnai delivery technologies
our goals for 2012
1 complete phase i clinical trial of atu027
2 announce results of atu027
3 advance atu111 and establish new preclinical programmes
4 complete new corporate alliance silence therapeutics plc annual report and accounts 201 1 business review · 09
three new delivery deals
the value of this portfolio of delivery technologies was 
underlined in 2011 with the signature of three agreements 
with new partners interna technologies bv mirna 
therapeutics inc and a top ten pharmaceutical company 
interestingly two of these three agreements were for a 
different form of rna therapeutic to the sirna approach 
being used by silence therapeutics ie microrna this 
emphasises the value of our delivery platform 
in september we established an agreement with 
interna technologies bv which is developing microrna 
mirna‑based therapeutics for cancer microrna 
intervention is an exciting new therapeutic area for which 
the silence technology platform is well suited and the 
deal was our first in this area we are looking forward to 
the results from this collaboration which we believe will 
demonstrate the potential of atuplex for the delivery 
of rna‑based therapeutics outside of the sirna arena 
under the agreement we will combine silence’s proprietary 
atuplex delivery system with interna’s novel micrornas 
to develop multiple novel candidate drugs the two companies 
will then undertake in vitro and in vivo studies of the candidate 
drugs and select lead candidates for further evaluation 
silence is eligible to receive up‑front fees as well as staged 
research payments if the collaboration progresses 
the potential of silence therapeutics’ delivery technologies 
in this new area was further underlined in october 2011 with our 
second mirna deal the collaboration with mirna therapeutics  
is to investigate the potential of both atuplex and our dbtc 
delivery system with our partner’s novel micrornas for the 
treatment of cancer we are pleased that our first deal on 
dbtc is in this exciting new therapeutic area silence 
therapeutics will formulate selected mirna sequences into 
atuplex and dbtc in order to generate candidate drugs 
which will then undergo in vitro and in vivo testing at mirna 
in order to select those to take forward for further evaluation 
in october 2011 we also signed an sirna delivery 
collaboration for dacc with a top ten pharmaceutical 
company – our first deal covering this technology for delivery 
to the lung under the terms of the agreement our partner 
will provide us with specific sirnas which we will formulate 
into the dacc delivery system silence and its partner will 
undertake in vitro and in vivo studies of the dacc‑formulated 
sirnas developed under the agreement and select lead 
candidates for further evaluation 
silence’s impressive pipeline of products not only validates the strength 
of the company’s technology but also the depth of knowledge that has 
guided the development path
products partners target  
tissueorgan
delivery  
method
market size discovery pre‑clinical phase i phase ii phase iib
pf‑4523655
diabetic macular  
edema
pfizerquark rtp801 – local delivery  
to the eye
naked sirna 1bn  
potential
pf‑4523655
agerelated macular 
degeneration
pfizerquark rtp801 – local delivery  
to the eye
naked sirna 31bn  
2010
qpi‑1002
prevention of delayed 
graft function
novartisquark p53 – systemic delivery  
to the kidney
naked sirna 44bn  
2010
qpi‑1002
acute kidney injury 
novartisquark p53 – systemic delivery  
to the kidney
naked sirna 1bn  
potential
aut027
solid tumours 
silence pkn3 – systemic delivery  
to tumour endothelium
atuplex 82bn  
angiogenesis  
mkt 2010
atu111
acute lung injury
silence systemic delivery  
to lung endothelium
dacc 1bn  
potential
liver diseases
dbtc programs
silence systemic delivery  
to liver hepatocytes  
and endothelium
dbtc undisclosed
lung diseases
dacc system 
silence systemic delivery  
to lung endothelium
dacc undisclosed 10 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
ongoing delivery collaborations progress
in addition to these exciting new deals we have an ongoing 
sirna delivery collaboration with dainippon sumitomo 
signed in 2008 under this collaboration we are jointly 
leveraging silence’s proprietary sirna molecules and 
delivery technologies to demonstrate delivery of rnai 
therapeutics to specific disease targets this agreement 
which originally included two drug targets was expanded 
in 2010 to include two more 
securing our financial position
silence therapeutics ended 2010 with cash reserves of 
£357m and we indicated in the first quarter of 2011 that 
we would be seeking additional funding to drive continued 
development of the company accordingly in may 2011 
silence successfully raised £551m net of expenses through 
a placing and open offer 
given the substantial financial and economic volatility 
experienced globally over the last few years particularly 
in the biotechnology sector we were extremely pleased with 
this result which gave us a substantially improved financial 
footing and extended the cash runway to the end of the 
third quarter of 2012 from existing cash resources alone 
the fundraising was supported by both existing and new 
shareholders whom we thank for their support and welcome 
to silence therapeutics 
part of the proceeds are to be used to among other things 
complete the ongoing phase i trial and initiate a phase ib 
trial of atu027 and advance preclinical development of the 
atu111 programme for lung disease as shareholders can 
see we have made progress in these areas and expect to 
continue to do so
a streamlined business focused 
on business development
increased financial efficiency
as 2011 progressed it became clear to silence therapeutics 
that in order to create a more streamlined and efficient business 
some streamlining and consolidation of operating sites was 
needed following the 2010 acquisition of intradigm inc 
managing and working across our three sites in the uk 
germany and the us had generated considerable operational 
difficulties as well as increased costs 
in april 2011 we announced plans to close our redwood 
city office in california this was completed in august 
as a consequence our us‑based chief executive officer 
dr phil haworth stepped down i joined the business in 
september initially as chief business officer but was 
delighted to be able to accept the appointment as chief 
executive officer in february 2012 following the departure 
of thomas christély who took on the role of chief executive 
officer briefly after the departure of dr haworth
with the us‑based business development and legal functions 
absorbed elsewhere in the group its operations are now 
based in berlin where our research and development 
facilities have always been located in addition there 
is a small management presence in london 
in addition to the closure of the us facility we were able 
to further streamline the business by reducing headcount 
in berlin from 32 to 27 via the loss of some non‑critical 
roles and by reducing the size of our board the latter had 
become too large following the acquisition of intradigm 
corporation and as a consequence dr james topper 
and dr david u’prichard resigned from the board of directors 
effective 29 july 2011 and 31 december 2011 respectively 
we thank both dr topper and dr u’prichard for their valuable 
contribution to silence therapeutics 
these measures helped us to increase our cash runway and 
combined with our fundraising mean that we have sufficient 
funding to last us until q3 2012 
significantly strengthened business 
development focus
with encouraging data so far from the phase i trial 
of atu027 and the level of interest in silence therapeutics’ 
rnai delivery technologies in 2011 it was clearly time 
to invest more significantly in our business development 
activities an important part of this will be the partnering 
with and generation of value from these assets in addition 
with the availability of finance significantly reduced in the 
current economic crisis the global biotechnology sector 
has increasingly accessed non‑dilutive financing from 
sources such as public sector organisations for example 
research councils and leading charities we consider 
this to be a major objective in our enhanced business 
development activity 
strong business development team
our business development activity was further enhanced 
in november 2011 with the appointment of dr georg buchner 
as vice president of business development georg was 
formerly vice‑president of corporate and business development 
at novacta biosystems ltd novacta prior to joining novacta 
georg was business development director at haptogen ltd 
where he was instrumental in the sale of the business to wyeth 
now part of pfizer in 2007 he has a phd in molecular genetics 
from king’s college london and an mba from the university 
of cambridge’s judge institute of management and will be 
working with myself to continue to broaden our collaborations 
with global pharmaceutical and biotechnology companies
chief executive’s review continued
“ in  2011  we  achieved  signifi cant  success  in  obtaining  new  issued  patents 
further strengthening protection of our innovative technologies” silence therapeutics plc annual report and accounts 201 1 business review · 11
strength through intellectual property
our broad and diverse intellectual property portfolio 
continues to provide us with a competitive advantage 
and a strong proprietary position in the rnai therapeutics 
space we believe that we have been successful in aggressively 
building one of the world’s most comprehensive rnai patent 
estates and expect that this asset will continue to offer 
significant support for our ongoing partnering activities 
our patent estate covers the areas which we believe to be 
pivotal to the successful development of rnai therapeutics 
from the structure of the molecules themselves to how they 
are delivered in addition we have achieved significant 
successes in establishing key levels of patent protection 
for our technologies in europe the us and japan offering 
opportunities in these important healthcare markets silence 
remains committed to the expansion and strengthening of 
its intellectual property portfolio in target markets around the 
globe in 2011 we made progress in both the us and japan 
covering rnai structures and delivery as well as receiving 
further confirmation of the strength of the zamore design 
rules patents as discussed below 
patent issuance and success versus challenges
in the us a new patent that broadens silence therapeutics’ 
existing protection of optimised rnai molecules including 
our proprietary aturnai platform was issued also in that 
territory we received a notice of allowance of a new patent 
that provides protection for a core component of our 
proprietary atuplex delivery platform 
protection in japan was enhanced by issuance of a patent 
covering novel aturnai molecules which will support 
our efforts to establish partnerships with leaders in the 
pharmaceutical industry there in addition we received 
news of issuance of a japanese patent covering methods 
for screening a therapeutic agent for the treatment andor 
prevention of any disease that involves elevated activity 
within the pi3‑kinase pathway this new intellectual property 
includes coverage for the use of the gene target protein 
kinase n beta ‘pkn3’ for screening of therapeutic agents 
and is important to us as pkn3 is the target of our leading 
therapeutic programme atu027 
our patents in this area were further supported in december 2011 
with a positive outcome from an oral hearing at the european 
patent office epo over the opposition to silence’s granted 
european patent ep 1 536 827 “further use of protein kinase 
n beta” the opposition division of the epo decided to uphold 
the patent in amended form now restricted to metastatic cancers 
this is the focus of silence’s ongoing atu027 phase i study 
and we are pleased that the product continues to be protected 
by this intellectual property and other patents for example 
those around atuplex and the aturnai sequence used 
in the product 
looking at atu027
silence’s lead internal rnai therapeutic candidate 
atu027 is currently in a phase i clinical trial atu027 has 
demonstrated anticancer activity against a broad range 
of tumour types including gastrointestinal nonsmall 
cell lung prostate melanoma breast and others
topline data presented at asco in june 2011 included 
results for 24 patients who received the study’s first eight 
doses of atu027
 i six of these patients experienced stable disease after 
three months
 i one patient with neuroendocrine cancer had disease 
stabilization for nine months
 i a second neuroendocrince cancer patient experienced 
partial regression of pulmonary metastases
 i a patient with breast cancer demonstrated regression 
of liver metastases
“ this positive data is very encouraging 
and we believe the disease stabilization 
and antitumor activity in particular 
are suggestive of a potential therapeutic 
be n e fi t  f o r  e x tr e m e l y  ill  p a ti e n ts  w h o 
have no other treatment options” 12 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
patent issuance and success versus challenges 
continued
silence has exclusive licences covering three patent families 
from the university of massachusetts medical school 
collectively known as the “zamore design rules” in 2011 
following an anonymous request four of the us patents 
covering the zamore design rules successfully completed 
re‑examination by the us patent and trademark office 
uspto and in december 2011 we were able to report 
that the uspto had issued “notices of intent to issue 
re‑examination certificates” in europe the patent is 
currently being opposed by alnylam and other parties
investor relations ir strategy 
silence therapeutics maintains active communications 
and an investor relations strategy to provide transparency 
and maximise dialogue with its stakeholders
as part of its 2011 ir strategy silence has held investor 
meetings across europe and attends investor conferences 
internationally throughout the year full details of which 
can be found on the company’s website 
httpsilence‑therapeuticscom 
in line with the london stock exchange’s aim requirements 
silence discloses its investor news on a frequent basis via 
its regulatory information service provider and the company 
holds a number of conference calls and meetings throughout 
the year in order to reach investors effectively in addition 
the company’s website serves as an effective tool for 
investor communications 
silence also participates in the evolving social media scene 
and communicated digitally online with frequency through 
linkedin facebookyoutube and recently twitter in february 
2012 silence launched its new website designed with a range 
of interactive features and online social media tools to reflect 
the new direction and more commercial focus of the company 
these included twitter feeds company news flashes and 
regular industry updates from its real‑time rnai hub 
summary and outlook
during 2011 silence therapeutics has built a significantly 
stronger business more able to deal with the rigours of 
today’s financial climate and better placed to exploit our 
wealth of assets by restructuring the business strengthening 
the management team and raising a significant amount of 
financing in challenging economic conditions we believe we 
have more than justified the decision made at the beginning 
of the year to remain an independent business 
exciting year ahead
2012 will be an important and exciting year for silence 
therapeutics with a new and commercially focused 
management team the company is set to achieve 
shareholder value uplift importantly there will be clinical 
data from us both for atu027 and our partnered products 
as well as other companies in the sector 2012 clinical news 
flow expected from us and our partners includes the anticipated 
start of phase ibiia clinical trials with atu027 this will be 
an important milestone for silence therapeutics 
as well as continuing to develop our pipeline key priorities 
for silence this year are to secure the company’s financial 
future and to continue to generate value through partnering 
our fundraising and moves to reduce cash burn this year 
have extended our cash runway to the end of the third quarter 
of 2012 not taking into account potential milestones from 
our collaboration partners 
with our enhanced business development function we will 
be looking at building value and generating income through 
our partnering activities one of our priorities in this area is 
the signature of out‑licensing or co‑development agreements 
for atu027 or other internal candidates such as atu111 
assuming they continue to generate encouraging data 
silence also believes that the quality of its rnai therapeutic 
platform – including aturnai and our portfolio of delivery 
technologies – will continue to be recognised by partners in 
licensing deals and research collaborations we are proud of 
our list of partners – which includes four of the top ten global 
pharmaceutical companies – and expect to add to it in 2012 
silence plans to attend scientific and medical conferences 
throughout the year in order to undertake a structured 
outreach to our key audiences we are pleased to confirm 
that during 2012 dr klaus giese silence’s chief scientific 
officer plans to present at a number of world‑leading 
biopharmaceutical events
another area of focus for the business development team 
will be looking at accessing non‑dilutive forms of financing 
such as grants from the large research charities in recent 
years this type of funding has grown in importance to the 
global biopharmaceutical sector partly driven by financial 
and economic conditions silence therapeutics considers 
it an important option for the company to develop our 
pipeline of therapeutics and build shareholder value 
providing as it does the foundation of our business 
we will continue to prosecute defend and grow our 
intellectual property portfolio areas of focus for additional 
patent protection include all essential components of rnai 
therapeutic development including multiple proprietary 
sirna delivery technologies potent sirna sequences 
and key sirna sequence and chemical modifications 
as well as specific high‑value disease targets
2012 looks to be an exciting year for us in concluding my 
comments it is important for me to note that the achievements 
we made in 2011 were only possible through the hard work 
and dedication of our staff and the support of our shareholders 
my thanks are due to all of you as we work together to bring 
much‑needed rnai therapeutics to patients 
tony sedgwick phd
chief executive officer
27 march 2012
chief executive’s review continued silence therapeutics plc annual report and accounts 201 1 business review · 13
financial review
“ silencesuccessfullystrengtheneditsfinancialpositioninmay2011
through a placing and open offer that generated net proceeds of £551m”
silence successfully strengthened its financial position in 
may 2011 through a placing and open offer that generated 
proceeds of £551m net of costs this funding provided 
cash resources that will support the company’s operations 
into the third quarter of 2012 this is without taking into 
account any milestone additional equity fundraisings 
or other such receipts that the company believes it 
could receive in 2012
revenue
revenue generated in the year decreased to £069m in 2011 
from £237m in 2010 revenue recognised in the year related 
to income from silence’s collaborations with astrazeneca 
and dainippon sumitomo the decrease in revenue in 2011 
primarily reflects lower income from dainippon sumitomo 
and the milestone from quark earned in 2010
research and development expenses
research and development expenses during the year 
decreased to £336m in 2011 from £582m in 2010 
the decrease in research and development expense 
is primarily driven by the closure of intradigm’s palo alto 
california research facility in april 2010 as well as by 
a reduction in headcount at the berlin research and 
development facility announced in august 2011
administrative expenses
administrative expenses during the year decreased to 
£312m £265m before restructuring charges in 2011 from 
£520m in 2010 the decrease in administrative expenses 
is again driven by the closure of the intradigm research 
facility in 2010 followed by the closure of the redwood city 
california facility in august 2011 as well as by a reduction 
in expenditure in the london head office the full benefit 
of these measures will be reflected in lower administrative 
costs onwards
financial income
financial income was £006m in 2011 compared to £010m in 
2010 interest income remained low on cash balances during 
2011 reflecting the continued low interest rate environment
taxation
corporation tax payable in both 2010 and 2011 was £nil
liquidity cash cash equivalents and money 
market investments
the group’s cash position at year end was £369m at the 
end of 2010 silence had cash of £357m a further £551m 
net of expenses was raised in may 2011 through a placing 
of 296693065 shares at 2p and open offer 
the net cash outflow from operating activities in 2011 was 
£511m 2010 £1055m against an operating loss of £579m 
2010 £866m primarily reflecting the impact of a reduction 
in other working capital of £026m 2010 £289m and 
non‑cash items such as depreciation amortisation and 
share option charges of £043m 2010 £098m 
trade and other receivables at year end were £017m 
2010 £078m the decrease reflects receipt of a milestone 
payment due from quark which was received in early 
january 2011 trade and other payables were £126m 
at year end 2010 £169m trade and other payables 
were lower at 31 december 2011 reflecting lower levels 
of expenditure 
goodwill at year end was £2834m 2010 £2835m 
the small decrease reflects currency translation effects 
other intangible assets at 31 december 2011 were £097m 
2010 £095m the increase in other intangible assets 
primarily reflects the additional licence fees paid relating 
to the zamore design rules patents
max herrmann
chief financial officer
27 march 2012
operating loss
2010 £866m
£579m
revenues
2010 £237m
£069m
group cash position
2010 £357m
£369m 14 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
jerry randall
non‑executive chairman
mr randall is an entrepreneur with interests in a number of business areas 
he was appointed chairman of the board in february 2010 following the 
resignation of iain ross until november 2009 he was chief financial officer 
of sinclair pharmaceuticals plc which he joined in 2000 as part of a management 
buy‑in team prior to this mr randall worked in corporate finance with gambit 
corporate finance and had previously been involved in two other buy‑ins he acted 
as adviser to both private and quoted companies between 1993 and 2000 in both 
the capacity of nominated adviser and in practice with kpmg during this period 
he was involved in a number of flotations and transactions on the official list 
unlisted securities market and aim as well as raising private equity mr randall 
is a qualified chartered accountant
max herrmann
c h i e ff i n a n c i a lo f fi c e ra n dc o m p a n ys e c r e t a r y
mr herrmann was appointed chief financial officer of silence therapeutics 
in may 2010 he is a qualified chartered accountant and possesses more than 
20 years of biotechnology and pharmaceutical industry experience having held 
key management positions with leading development stage companies as well 
as several investment banks prior to joining silence mr herrmann served as 
chief financial officer of intercytex group plc a publicly traded company focused 
on the emerging area of regenerative medicine before joining intercytex he spent 
over ten years as a sell‑side equity analyst most recently as managing director 
and head of european pharmaceutical and biotechnology research at ing he has 
also held the position of financial controller for us‑based onyx pharmaceuticals 
inc and currently serves on the board of regenerative medicine assets limited
tony sedgwick
c h i e fe x e c u t i veo f fi c e r
dr sedgwick is an experienced biotechnology and pharmaceutical entrepreneur 
with extensive experience in small and large company transactions and will assume 
responsibility for the broadening of silence’s partnerships he was most recently 
chief executive officer of the uk biotech company novacta and chairman of 
the norwegian biotech company plastid as previously tony was chief executive 
officer of the uk biotech company daniolabs ltd and the uk biotech company 
cambridge biotechnology ltd both companies being successfully exited by trade 
sale tony has been an executive and non‑executive director of a large number of 
life sciences companies in the uk and continental europe between 1986 and 2002 
tony worked for f hoffmann‑la roche in several senior management roles latterly 
as global head of clinical operations and uk development director
board of directors silence therapeutics plc annual report and accounts 201 1 corporate governance · 15
annette clancy
non‑executive director
ms clancy has had a distinguished career spanning 30 years with glaxosmithkline 
gsk she spent 15 years in business development at gsk and led their global 
transactions and alliance management teams during her last three years at gsk 
during her tenure she and her team were responsible for concluding a large number 
of research development and commercial business collaborations on behalf of 
gsk prior to her role in business development ms clancy held a number of 
positions in clinical research research and development project management 
and commercialisation ms clancy has a bsc hons pharmacology from 
bath university in the uk
dr david mack
non‑executive director
dr mack is a director at alta partners where he led the investment in angiosyn as 
a director and acting ceo acquired by pfizer in 2005 he joined intradigm’s board 
in may 2006 and served on that board until the merger with silence therapeutics 
he is currently on the board of directors of aerie pharmaceuticals ceregene and 
proacta prior to alta dr mack co‑founded and served as vice president of genomics 
research at eos biotechnology acquired by protein design labs in 2003 from 
1995 to 1997 he served at affymetrix as head of cancer biology where he oversaw 
the development and application of dna array technology in the areas of oncology 
and inflammation he was also a pivotal member of the polymerase chain reaction 
‘pcr’ invention group at cetus now chiron in the mid 1980s dr mack received 
his phd in 1992 from the university of chicago 
committee composition
audit committee  
assisting board oversight of 
accounting and financial reporting 
processes and the audits of the 
company’s financial statements 
 i jerry randall chairman
 i annette clancy
nominations and 
governance committee 
recommending to the board those 
persons to be nominated for election as 
directors at any shareholders meeting 
 i annette clancy chairman
 i david mack
remuneration committee  
assisting the board in the 
discharging of its responsibilities 
related to remuneration of the 
company’s executive officers 
 i annette clancy chairman
 i david mack
 i jerry randall 16 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
directors’ report
the directors present their report and the financial statements for the year ended 31 december 2011
principal activities
the group carries out research and development of pharmaceutical products in particular the group is focused on the development 
of rnai therapeutics which incorporates its structural chemistry and delivery technologies the group’s lead product atu027 
is currently in a phase i clinical trial
review of the business and future developments
the chairman’s statement above provides details of the group’s progress during the year against all its performance targets the 
chief executive’s review on pages 6 to 12 describes the research and development activity during the year and outlines future planned 
developments the product development pipeline is also shown above with a briefing on the group’s technology details of the financial 
performance including comments on the cash position and research and development expenditure are given in the financial review 
section on page 13 the group’s kpis are the cash position in relation to cash flow the expenditure on research and development 
activities and the development milestones reached together with the signing of research collaborations and licences to bring in both 
development partners and revenues  
health safety and environment
the directors are committed to ensuring the highest standards of health and safety both for their employees and for the communities 
within which the group operates the directors are also committed to minimising the impact of the group’s operations on the environment 
for example the group has implemented paper recycling at its head office
employees
the directors are committed to continuing involvement and communication with employees on matters affecting both the employees 
and the company management conducts regular employee site meetings
subsequent events
a description of subsequent events is set out in note 27 to the financial statements
results and dividends
the group recorded a loss for the year before taxation of £5736563 2010 £8795274 further details are given in the preceding 
financial review the group is not yet in a position to pay a dividend 2010 £nil and the loss for both periods has been added to 
the retained loss
financial and non‑financial key performance indicators kpis
the directors consider cash and research and development spend to be the group’s financial kpis at the current stage of the 
company’s development these are detailed in the financial review on page 13 the directors consider that the most important 
non‑financial kpis relate to the number of drugs in development by stage of development the number of pharmaceutical collaborations 
the development milestones reached and the signature of research collaborations and licences all of which are detailed in the chief 
executive’s statement on pages 6 to 12
directors
the directors who served at any time during the year were
chairman j a p randall 
executive directors t christély appointed 19 september 2011 resigned 9 february 2012
t sedgwick appointed 9 february 2012
p haworth resigned 1 august 2011
m herrmann  
non‑executive directors a clancy
d mack  
j topper resigned 29 july 2011
d c u’prichard resigned 31 december 2011
the interests of the directors in the share options of the company are set out in note 19 to the financial statements  silence therapeutics plc annual report and accounts 201 1 corporate governance · 17
substantial interests
at 31 december 2011 the company had been informed of the following substantial interests of over 3 in the issued share capital 
of the company
number
percentage of
issued
share capital
robert keith 51989628 901
hedger management 50000000 866
frazier healthcare ventures 27265465 472
walker crips 26759101 464
southern fox investments 26173913 454
acp capital 25356422 439
simpson financial 25000000 433
corporate governance
the board meets regularly and has ultimate responsibility for the management of the group and sub‑committees comprising 
non‑executive directors meeting as and when required to deal with remuneration and audit matters
committee structure
remuneration a clancy chair jap randall and d mack 
audit jap randall chair and a clancy
nominations and governance a clancy chair and d mack
remuneration committee
the group has established a remuneration committee now comprising three non‑executive directors to determine and review the 
emolument packages of the directors of both the parent and subsidiary companies the committee meets at least twice a year and is 
responsible for setting the group’s overall policy on executive remuneration and employment conditions including setting the specific 
remuneration benefits and terms of employment for each executive director
the board of directors has considered the remuneration committee’s proposals in respect of the remuneration of the directors and 
senior executives and has accepted them without substantial revision
audit committee
the board seeks to present a balanced and understandable assessment of the group’s position and prospects in all interim final and 
price‑sensitive reports and information required to be presented by statute
the audit committee comprises of two non‑executive directors and its terms of reference include keeping under review the scope and 
results of the external audit and its cost effectiveness the committee reviews the independence and objectivity of the external auditors 
kpmg audit plc including the nature and extent of any non‑audit services supplied by them to the group 
nominations and corporate governance committee
the nominations and corporate governance committee is chaired by a clancy d mack is also a member of the committee 
the committee recommends to the board appointment of new directors having applied objective criteria in making any nomination 
to ensure the board has a balance of relevant skills and experience it also evaluates the structure size and composition of the board 
and recommends any changes to the membership of the board it considers appropriate and assesses the independence of non‑executive 
directors the nominations committee met once during the year and the meeting was fully attended
shareholder communications
the company uses its corporate website wwwsilence‑therapeuticscom to ensure that the latest announcements press releases and 
published financial information are available to all shareholders and other interested parties
the agm is used to communicate with both institutional shareholders and private investors and all shareholders are encouraged to 
participate separate resolutions are proposed on each issue so that they can be given proper consideration and there is a resolution 
to approve the annual report and accounts the company counts all proxy votes and will indicate the level of proxies lodged on each 
resolution after it has been dealt with by a show of hands 18 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
directors’ report continued
disclosure of information to auditors
the directors who held office at the date of approval of this directors’ report confirm that so far as they are each aware there is no 
relevant audit information of which the company’s auditors are unaware and each director has taken all the steps that they ought to 
have taken as a director to make themselves aware of any relevant audit information and to establish that the company’s auditors are 
aware of that information
auditors 
in accordance with section 489 of the companies act 2006 a resolution for the re‑appointment of kpmg audit plc as auditors 
of the company is to be proposed at the forthcoming annual general meeting 
directors’ responsibilities for the financial statements
the directors are responsible for preparing the annual report and financial statements in accordance with applicable law and 
regulations company law requires the directors to prepare financial statements for each financial year as required by the aim rules 
of the london stock exchange they are required to prepare the group financial statements in accordance with ifrss as adopted by 
the eu eu‑ifrs and applicable law and have elected to prepare the parent company financial statements on the same basis 
under company law the directors must not approve the financial statements unless they are satisfied that they give a true and fair view 
of the state of affairs of the group and parent company and of their profit or loss for that period 
in preparing each of the group and parent company financial statements the directors are required to
 i select suitable accounting policies and then apply them consistently
 i make judgements and estimates that are reasonable and prudent
 i state whether they have been prepared in accordance with eu‑ifrs and
 i prepare the financial statements on the going concern basis unless it is inappropriate to presume that the group and the parent 
company will continue in business
the directors are responsible for keeping adequate accounting records that are sufficient to show and explain the parent company’s 
transactions and disclose with reasonable accuracy at any time the financial position of the parent company and enable them to ensure 
that its financial statements comply with the companies act 2006 they have general responsibility for taking such steps as are 
reasonably open to them to safeguard the assets of the group and to prevent and detect fraud and other irregularities
the directors are responsible for the maintenance and integrity of the corporate and financial information included on the company’s 
website legislation in the uk governing the preparation and dissemination of financial statements may differ from legislation in 
other jurisdictions
risk factors
the group’s principal activity is biotechnology research and development as with any business in this sector there are risks and 
uncertainties relevant to the group’s business certain of these risk factors affect the majority of businesses some are common to 
businesses in the biotechnology sector and others are more specific to the group
risks common to most businesses
 i failure to maintain legal and regulatory compliance
 i new accounting standards causing a material adverse impact on reported financial results
 i failure to balance product portfolio against market projections and demands
 i increasing cost and decreasing availability of insurance
 i lack of control over external economic factors affecting business
 i unforeseen events which would be classified as force majeure eg fire flood loss of utilities
 i inability to access sufficient resources to trade as a going concern silence therapeutics plc annual report and accounts 201 1 corporate governance · 19
risk factors continued
risks applicable to the biotechnology sector and the group
clinical and regulatory risk
 i the nature of pharmaceutical development is such that drug candidates may not be successful due to an inability to demonstrate 
in a timely manner the necessary safety and efficacy in a clinical setting to the satisfaction of appropriate regulatory bodies such as 
the food and drug administration fda in the us and the european medicines agency ema in europe the group will have limited 
control over the type and cost of trial required to obtain regulatory approval 
 i the group will rely on third parties to conduct clinical trials if these third parties do not successfully carry out their contractual duties 
or meet expected deadlines the programmes of the group may be delayed or the group may not be able to obtain regulatory approval 
for its products any failure or delay of projects in development or clinical trials could have an adverse effect on the business 
 i with the prime focus of the group being on such a new area of technology there can be no assurance that the group’s products will 
receive and maintain regulatory approval 
product development risk
 i the group is involved at the leading edge of a revolutionary technology within the pharmaceutical sector more drugs fail in 
development than progress to market and there is no guarantee that the group will be able to successfully develop this new 
technology or bring any of the drug candidates it is developing to market further the drugs that the group does bring to market may 
not be commercially successful
 i the group has no track record of successful development and registration of any product and will need to acquire or gain access to 
relevant additional expertise
 i in order to progress the group’s product development plans it may be desirable or necessary to find collaborators on certain 
projects the group cannot guarantee that it will be able to find and maintain suitable collaborators under acceptable terms or that 
once found such collaborators will devote sufficient resources to the collaboration to make it commercially successful 
 i the group’s suppliers may encounter unexpected difficulties in the design and construction of manufacturing processes and the 
scale‑up of production to viable commercial levels or may otherwise be unable to supply materials to the group in a timely manner 
 i competition for talented employees in the biotechnology sector may lead to increased costs or decreased availability of staff as a 
result the group may be unable to recruit or retain certain important employees this could weaken the group’s scientific and 
management capabilities and could delay or halt the development of products and technologies 
competition risk
 i rnai technology is attracting increased interest and with that increased competition competitors in the sector may have greater 
financial human and other resources and more experience to develop competing products or technology
 i many companies are trying to develop competing technologies and one or more of these may restrict the potential commercial 
success of the group’s products or render them obsolete 
 i increasing competition may also have an adverse effect on the timing or scale of commercialisation of the group’s technology 
intellectual property risk
 i intellectual property issues from challenges by others or lack of protection for its own products may negatively impact the group 
other companies may have or develop intellectual property that restricts the group’s freedom of use or imposes high additional costs 
to obtain licences 
 i the group may be unable to successfully establish and protect its intellectual property which is significant to the group’s 
competitive position
 i the group’s intellectual property may become invalid or expire before its products are successfully commercialised
 i the group may be unable to successfully protect its competitive position through the establishment and enforcement of intellectual 
property the lack of sufficient intellectual property protection for the group’s technologies may have a material adverse effect on its 
commercial success in particular there can be no assurance that the group’s patent and other intellectual property applications 
will be granted or that its granted intellectual property patents including any granted in future further to those applications are or 
will be valid or of sufficiently broad scope to provide commercially meaningful protection against third party competition the group’s 
competitors may also have or acquire in future substantially equivalent technologies to those on which the group does or will depend 
or otherwise design around the group’s intellectual property 20 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
directors’ report continued
risk factors continued
risks applicable to the biotechnology sector and the group continued
intellectual property risk continued
 i other companies may have or acquire intellectual property that restricts the group’s freedom to operate or imposes high additional 
costs for the group in obtaining licences and there can be no assurance that the group will be able to design around such intellectual 
property or obtain relevant licences on commercially acceptable terms if at all
 i the group may incur substantial costs in enforcing its intellectual property and in bringing and prosecuting opposition or interference 
actions to seek to prevent third parties from obtaining patent or other protection the group may incur substantial costs in defending 
against such actions there can be no guarantee that such actions will be successful for the group
 i the patent landscape in the field of rnai is complex and the group is aware of the issuance and the pendency of patents and patent 
applications in europe the us and in other jurisdictions that are owned by third parties and that purport to cover structurally defined 
classes of sirnas and their uses this patent landscape is in flux with ongoing oppositions litigations and continuing prosecution 
before patent offices around the world and the directors cannot be certain that sirna claims issued to third parties to date or in the 
future will not restrict the group’s freedom to operate
 i in addition there are many issued and pending patents that claim various aspects of oligonucleotide chemistry that the directors may 
need to apply to the group’s sirna drug candidates there are also many issued patents that claim genes or portions of genes that 
may be relevant for sirna drugs we wish to develop there are further many issued and pending patents that claim various aspects 
of nucleic acid delivery systems that the directors may need to license in order to deliver the group’s sirna drug candidates topically 
or systemically to the appropriate target tissues thus it is possible that one or more third parties may hold or later will hold patent 
rights to which the group will need a licence if those parties refuse to grant the group a licence to such patent rights on reasonable 
terms the group may not be able to perform research with or market products covered by these patents
 i the group also relies on trade secrets know‑how and technology which are not protected by patents to maintain its competitive 
position if any trade secret know‑how or other technology not protected by a patent were to be disclosed to or independently 
developed by a competitor the group’s business and financial condition could be materially adversely affected
retention of key personnel
 i the group’s success is largely dependent on the personal efforts and abilities of the group’s existing senior management the loss 
of key employees or advisers or the inability to attract or retain other qualified employees or advisers could have a material adverse 
effect on the group’s results operations and financial condition
financial risk
 i there are very high costs of product development where products have lead times to market of many years
 i the lack of a substantial recurrent revenue stream and the significant resources needed for ongoing investment in its research and 
development pipeline require the group to gain access to additional funding from licensing capital markets or elsewhere there can 
be no assurances that such funding will be achieved on favourable terms if at all 
 i additional funding will be required to give the group time to reach profitability if the group is unable to raise those funds there may 
be insufficient finance for product development or operations and consequent delay reduction or elimination of development 
programmes could result 
 i the group has a small portfolio of products success or failure with individual products could have a significant impact on the share 
price this in turn may make it difficult for the group to continue funding its development programme 
 i the group may be unable to secure adequate insurance at an acceptable cost
 i the group has operations in the uk germany and the us and therefore the group will be exposed to risks associated with foreign 
currency exchange rates and fluctuation therein
this list should not be considered an exhaustive statement of all potential risks and uncertainties silence therapeutics plc annual report and accounts 201 1 corporate governance · 21
going concern
the financial statements have been prepared on a going concern basis that assumes that the group and parent company will continue 
in operational existence for the foreseeable future
the group had a net cash outflow from operating activities for the year ended 31 december 2011 of £511m and at 31 december 2011 
had cash balances of £369m post 31 december 2011 the group has continued to progress its research and development programmes 
resulting in a further net cash outflow of £086m to 29 february 2012 at 29 february 2012 the group’s cash balances stood at £283m 
the group’s cash flow forecasts based on current levels of research and development expenditure administrative costs and contracted 
cash inflows show that the group will require additional funding during the third quarter of 2012 the group does not currently have any 
overdraft or loan facilities 
the directors have a reasonable expectation that further finances will become available during the course of 2012 through a combination 
of sources including equity fundraisings grants milestone payments from existing agreements and licence fees from entering into new 
agreements with business partners
the directors having prepared cash flow forecasts believe that existing cash resources together with additional funds provided by 
equity fundraisings grants milestone payments and licence fees will provide sufficient funds for the group to continue its research and 
development programmes and to remain in operation for at least twelve months from the date of approval of these financial statements 
the directors have also taken a number of steps to reduce expenditure during the last twelve months including the closure of the 
group’s us operations in redwood city california
the directors have concluded that there is a material uncertainty as to the amount and timing that funds will be obtained from equity 
fundraisings grants milestone payments and licence fees the directors also note that the failure to obtain sufficient funding from any 
or all of these sources would cast significant doubt on the group’s ability to continue as a going concern the group and company may 
therefore be unable to continue realising their assets and discharging their liabilities in the normal course of business
the directors consider that the continued adoption of the going concern basis is appropriate and the financial statements do not reflect 
any adjustments that would be required if they were to be prepared on any other basis
the group’s business activities together with the factors likely to affect its future development performance and position are set out 
in the chief executive’s review on pages 6 to 12 the financial position of the group its cash flows and liquidity position are as set out in 
the financial review on page 13
political and charitable donations
the group made no political or charitable donations during 2011 2010 £nil
payment of creditors
it is the group’s policy to make payments to creditors in accordance with individually agreed terms generally within 30 days either 
of the invoice date or from the end of the month the invoice was received using the method set out in the companies act the ratio 
for the group of trade creditors at the year end to total costs was 49 days 2010 22 days
 
on behalf of the board
jerry randall 
chairman 
27 march 2012  22 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
independent auditors’ report
to the members of silence therapeutics plc
we have audited the financial statements of silence therapeutics plc for the year ended 31 december 2011 as set out on pages 23 to 
52 the financial reporting framework that has been applied in their preparation is applicable law and international financial reporting 
standards ifrss as adopted by the eu and as regards the parent company financial statements as applied in accordance with the 
provisions of the companies act 2006
this report is made solely to the company’s members as a body in accordance with chapter 3 of part 16 of the companies act 2006 
our audit work has been undertaken so that we might state to the company’s members those matters we are required to state to them 
in an auditors’ report and for no other purpose to the fullest extent permitted by law we do not accept or assume responsibility to anyone 
other than the company and the company’s members as a body for our audit work for this report or for the opinions we have formed
respective responsibilities of directors and auditors
as explained more fully in the directors’ responsibilities statement set out on page 18 the directors are responsible for the preparation 
of the financial statements and for being satisfied that they give a true and fair view our responsibility is to audit and express an opinion 
on the financial statements in accordance with applicable law and international standards on auditing uk and ireland those 
standards require us to comply with the auditing practices board’s apb’s ethical standards for auditors
scope of the audit of the financial statements
a description of the scope of an audit of financial statements is provided on the apb’s website at wwwfrcorgukapbscopeprivatecfm
opinion on financial statements
in our opinion
 i the financial statements give a true and fair view of the state of the group’s and of the parent company’s affairs as at 31 december 
2011 and of the group’s loss for the year then ended
 i the group financial statements have been properly prepared in accordance with ifrss as adopted by the eu
 i the parent company financial statements have been properly prepared in accordance with ifrss as adopted by the eu and as 
applied in accordance with the provisions of the companies act 2006 and
 i the financial statements have been prepared in accordance with the requirements of the companies act 2006
emphasis of matter – going concern
in forming our opinion on the financial statements which is not modified we have considered the adequacy of the disclosure made 
in note 23 to the financial statements concerning the group’s and the parent company’s ability to continue as a going concern 
in particular the receipt of sufficient additional funds including the successful completion of an equity fundraising represents a material 
uncertainty that may cast significant doubt on the group’s and the parent company’s ability to continue as a going concern 
the financial statements do not include the adjustments that would result if the group and the parent company were unable to continue 
as a going concern
opinion on other matter prescribed by the companies act 2006
in our opinion the information given in the directors’ report for the financial year for which the financial statements are prepared 
is consistent with the financial statements
matters on which we are required to report by exception
we have nothing to report in respect of the following matters where the companies act 2006 requires us to report to you if in our opinion
 i adequate accounting records have not been kept by the parent company or returns adequate for our audit have not been received 
from branches not visited by us 
 i the parent company financial statements are not in agreement with the accounting records and returns 
 i certain disclosures of directors’ remuneration specified by law are not made or
 i we have not received all the information and explanations we require for our audit
richard broadbelt 
senior statutory auditors
for and on behalf of kpmg audit plc statutory auditor chartered accountants 
15 canada square london e14 5gl 
27 march 2012  silence therapeutics plc annual report and accounts 201 1 financial statements · 23
consolidated income statement
year ended 31 december 2011
2011
note
ongoing
operations
£
restructuring
£
2011
£
2010 
£
revenue 3 693555 — 693555 2365877
research and development costs 3360442 — 3360442 5821212
gross loss 2666887 — 2666887 3455335
administrative expenses 2647189 471825 3119014 5202938
operating loss 5 6 5314076 471825 5785901 8658273
finance income 7 56646 — 56646 95343
finance expense 12817 — 12817 63295
gainloss on sale of assets 5509 — 5509 169049
loss before taxation 5264738 471825 5736563 8795274
taxation 8 — — — —
loss for the year attributable to owners 
of the parent company 5264738 471825 5736563 8795274
loss per share basic and diluted 9 11p 01p 12p 316p
the accompanying accounting policies and notes form an integral part of these financial statements 
consolidated statement of comprehensive income
year ended 31 december 2011
2011
£
2010
£
loss for the year after taxation 5736563 8795274
other comprehensive income
 – exchange differences arising on consolidation of foreign operations 4472 151696
total comprehensive income for the year attributable to owners of the parent company 5732091 8643578
the accompanying accounting policies and notes form an integral part of these financial statements 24 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
consolidated balance sheet
at 31 december 2011
note
2011
£
2010
£
non‑current assets
property plant and equipment 11 224980 287613
goodwill 12 28342109 28346276
other intangible assets 13 971154 945391
29538243 29579280
current assets
inventory — 27438
trade and other receivables 15 174346 782596
investments held for sale 37423 —
cash and cash equivalents 16 3687860 3566877
3899629 4376911
current liabilities
trade and other payables 17 1259984 1686516
1259984 1686516
total assets less current liabilities 32177888 32269675
net assets 32177888 32269675
equity
share capital 19 5771145 2798915
capital reserves 20 81141424 80269278
translation reserve 3037175 3032703
retained loss 57771856 53831221
total equity 32177888 32269675
the financial statements were approved by the board of directors on 27 march 2012
max herrmann
chief financial officer
the accompanying accounting policies and notes form an integral part of these financial statements
company number 02992058 silence therapeutics plc annual report and accounts 201 1 financial statements · 25
consolidated statement of changes in equity
year ended 31 december 2011
share
capital
£
capital
reserves
£
translation
reserve
£
retained
loss
£
total
equity
£
at 1 january 2010 1350334 49810071 2881007 45150257 8891155
recognition of share‑based payments — 760053 — — 760053
transfer upon
 – exercise of options in year — — — — —
 – lapse of vested options in year — 2477 — 2477 —
 – lapse of vested warrants in year — 111833 — 111833 —
shares issued in the year 1448581 29813464 — — 31262045
transactions with owners 1448581 30459207 — 114310 32022098
loss for the period — — — 8795274 8795274
other comprehensive income 
exchange differences arising on consolidation of foreign 
operations — — 151696 — 151696
total comprehensive income for the year attributable 
to owners of the parent company — — 151696 8795274 8643578
at 31 december 2010 2798915 80269278 3032703 53831221 32269675
recognition of share‑based payments — 120474 — — 120474
transfer upon
 – exercise of options in year — — — — —
 – lapse of vested options in year — 1795928 — 1795928 —
 – issued warrants in year — 795 — — 795
shares issued in the year 2972230 2546805 — — 5519035
transactions with owners 2972230 872146 — 1795928 5640304
loss for the period — — — 5736563 5736563
other comprehensive income 
exchange differences arising on consolidation 
of foreign operations — — 4472 — 4472
total comprehensive income for the year attributable 
to owners of the parent company — — 4472 5736563 5732091
at 31 december 2011 5771145 81141424 3037175 57771856 32177888
 26 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
company balance sheet
year ended 31 december 2011
note
2011
£
2010
£
non‑current assets
property plant and equipment 11 3313 —
investment in subsidiary undertakings 14 54217931 50615307
54221244 50615307
current assets
trade and other receivables 15 79492 46024
cash and cash equivalents 16 3322705 2283300
3402197 2329324
current liabilities
trade and other payables 17 181885 249846
181885 249846
total assets less current liabilities 57441556 52694785
net assets 57441556 52694785
equity
share capital 19 5771145 2798915
capital reserves 20 80957508 80085362
retained loss 29287097 30189492
total equity 57441556 52694785
the financial statements were approved by the board of directors on 27 march 2012
max herrmann
chief financial officer
the accompanying accounting policies and notes form an integral part of these financial statements
company number 02992058 silence therapeutics plc annual report and accounts 201 1 financial statements · 27
company statement of changes in equity
year ended 31 december 2011
share
capital
£
capital
reserves
£
retained
loss
£
total
equity
£
at 1 january 2010 1350334 49626155 28218220 22758269
loss for the period — — 2083105 2083105
recognition of share‑based payments — 760053 — 760053
transfer upon
 – exercise of options in year — — — —
 – lapse of vested options in year — 2477 — 2477
 – lapse of vested warrants in year — 111833 111833 —
shares issued in the year 1448581 29813464 — 31262045
movement in the year 1448581 30459207 1971272 29936516
at 31 december 2010 2798915 80085362 30189492 52694785
loss for the period — — 893533 893533
recognition of share‑based payments — 120474 — 120474
transfer upon
 – exercise of options in year — — — —
 – lapse of vested options in year — 1795928 1795928 —
 – issued warrants in year — 795 — 795
shares issued in the year 2972230 2546805 — 5519035
movement in the year 2972230 872146 902395 4746771
at 31 december 2011 5771145 80957508 29287097 57441556 28 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
cash flow statements
year ended 31 december 2011
group company
2011
£
2010
£
2011
£
2010
£
cash flow from operating activities
loss before taxation 5736563 8795274 893533 2083105
depreciation charges 91355 141689 274 —
amortisation charges 213578 181604 — —
gainloss on sale of property plant and equipment 5509 169049 — —
charge for the year in respect of share‑based payments 121269 659018 28114 267447
increasereduction in impairment provision against loan to subsidiary — — 3242 152337
finance income 56646 95343 284592 124866
finance expense 12817 63295 — —
5359699 7675962 1146495 2092861
decreaseincrease in trade and other receivables 665962 43948 33468 45213
decreaseincrease in inventory 27438 27438 — —
increasedecrease in trade and other payables 431010 2819261 67961 935859
cash absorbed by operations 5097309 10566609 1247924 2983507
taxation received — 59198 — —
interest paid 12817 44302 — —
net cash outflow from operating activities 5110126 10551713 1247924 2983507
cash flow from investing activities
acquisition of business — 746108 — —
investment in assets held for sale 6290 — — —
proceeds from sale of property plant and equipment 10185 66407 — —
investment in subsidiary undertakings — — 598046 5554405
increase in loans to subsidiary undertakings — — 2914665 4020223
interest received 26764 37565 284592 124866
additions to property plant and equipment 26892 31539 3587 —
additions to intangible assets 247586 259980 — —
net cash used ingenerated from investing activities 243819 558561 3231706 9449762
cash flow from financing activities
proceeds from issue of share capital 5519035 14358313 5519035 14358313
repayment of notes payable — 1940492 — —
net cash generated from financing activities 5519035 12417821 5519035 14358313
increase in cash and cash equivalents 165090 2424669 1039405 1925044
cash and cash equivalents at start of year 3566877 1131146 2283300 358256
net increase in the year 165090 2424669 1039405 1925044
effect of exchange rate fluctuations on cash held 44107 11062 — —
cash and cash equivalents at end of year 3687860 3566877 3322705 2283300 silence therapeutics plc annual report and accounts 201 1 financial statements · 29
cash flow statements continued
year ended 31 december 2011
group company
2011
£
2010
£
2011
£
2010
£
cash and cash equivalents includes
instant access bank accounts 3687860 3566877 3322705 2283300
supplementary disclosure of non‑cash items
issuance of share capital for merger acquisition — — — 16903732
share‑based compensation issued as partial consideration 
for merger acquisition — — — 101035
investment in subsidiary undertakings through issuance 
of share‑based compensation — — 93154 391571
reduction in investment through lapse of vested options 1795928 — 1795928 2477
the accompanying accounting policies and notes form an integral part of these financial statements 30 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements
year ended 31 december 2011
1 general information
11 group
silence therapeutics plc “silence therapeutics” or “the company” and its subsidiaries together “the group” are primarily involved 
in the research and development of novel pharmaceutical products silence therapeutics plc a public limited company incorporated 
and domiciled in england is the group’s ultimate parent company the address of silence therapeutics’ registered office is 22 melton street 
london nw1 2ep and the principal place of business is the royal institution of great britain 21 albemarle street london w1s 4bs
12 company income statement
the company has taken advantage of section 408 of the companies act 2006 and has not included its own profit and loss account 
in these financial statements the loss for the financial year dealt with in the accounts of the company including provision against 
the loans to and investments in subsidiary companies amounted to £893533 2010 loss £2083105
2 principal accounting policies
21 basis of preparation
both the parent company and the group financial statements have been prepared in accordance with the companies act 2006 and 
international financial reporting standards ‘ifrs’ as adopted by the eu under the historical cost convention  the accounting policies 
set out below have unless otherwise stated been applied consistently to all periods presented in these consolidated financial 
statements the accounts are prepared in pounds sterling and presented to the nearest pound
the group has not adopted the following new ifrs and international accounting standards ias that have been issued but are not yet effective
effective from
ifrs 9 financial instruments 1 january 2015
ifrs 10 consolidated financial statements 1 january 2013
ifrs 11 joint arrangements 1 january 2013
ifrs 12 disclosure of interests in other entities 1 january 2013
ifrs 13 fair value measurement 1 january 2013
ias 19 employee benefits amended 2011 1 january 2013
ias 27 separate financial statements 2011 1 january 2013
ias 28 investments in associates and joint ventures 2011 1 january 2013
with the exception of ifrs10 consolidated financial statements the ifrs and international accounting standards ias above are not 
expected to have a significant impact on the financial statements when they become effective
the following standards amendments and interpretations have been applied for the first time in the year under review
 i ias 24 revised 2010 related party disclosures the revised standard does not have a material impact on the group’s financial statements
 i ifric 14 amendment to prepayments of a minimum funding requirement adoption of the amendment has not had a significant 
impact on the group financial statements
the principal accounting policies adopted are set out below
22 basis of consolidation
the group financial statements consolidate those of the company and its controlled subsidiary undertakings drawn up to 31 december 2011 
control is achieved where the company has the power to govern the financial and operating policies of the entity so as to obtain benefits from 
its activities the parent company financial statements present information about the company as a separate entity and not about its group
the results of subsidiaries acquired or disposed of during the year are included in the consolidated income statement from the effective 
date of acquisition or up to the effective date of disposal
where necessary adjustments are made to the financial statements of subsidiaries to bring accounting policies into line with those used 
for reporting the operations of the group all intra‑group transactions balances income and expenses are eliminated on consolidation
23 going concern
the financial statements have been prepared on a going concern basis that assumes that the group and parent company will continue 
in operational existence for the foreseeable future
the group had a net cash outflow from operating activities for the year ended 31 december 2011 of £511m and at 31 december 2011 
had cash balances of £369m post 31 december 2011 the group has continued to progress its research and development programmes 
resulting in a further net cash outflow of £086m to 29 february 2012 at 29 february 2012 the group’s cash balances stood at £283m 
the group’s cash flow forecasts based on current levels of research and development expenditure administrative costs and contracted 
cash inflows show that the group will require additional funding during the third quarter of 2012 the group does not currently have 
any overdraft or loan facilities  silence therapeutics plc annual report and accounts 201 1 financial statements · 31
2 principal accounting policies continued
23 going concern continued
the directors have a reasonable expectation that further finances will become available during the course of 2012 through a combination 
of sources including equity fundraisings grants milestone payments from existing agreements and licence fees from entering into new 
agreements with business partners
the directors having prepared cash flow forecasts believe that existing cash resources together with additional funds provided by equity 
fundraisings grants milestone payments and licence fees will provide sufficient funds for the group to continue its research and development 
programs and to remain in operation for at least twelve months from the date of approval of these financial statements the directors have 
also taken a number of steps to reduce expenditure during the last twelve months including the closure of the group’s us operations 
in redwood city california
the directors have concluded that there is a material uncertainty as to the amount and timing that funds will be obtained from equity 
fundraisings grants milestone payments and licence fees the directors also note that the failure to obtain sufficient funding from any 
or all of these sources would cast significant doubt on the group’s ability to continue as a going concern the group and company may 
therefore be unable to continue realising their assets and discharging their liabilities in the normal course of business
the directors consider that the continued adoption of the going concern basis is appropriate and the financial statements do not reflect 
any adjustments that would be required if they were to be prepared on any other basis
the group’s business activities together with the factors likely to affect its future development performance and position are set out in 
the chief executive’s review on pages 6 to 12 the financial position of the group its cash flows and liquidity position are as set out in 
the financial review on page 13
24 business combinations
there were no business combinations as defined by ifrs 3 revised during 2011 business combinations that occurred in 2010 
including the acquisition of intradigm which was completed on 5 january 2010 are accounted for by applying the acquisition method 
described in ifrs 3 revised as at the acquisition date which is the date on which control is transferred to the group in arriving at the 
cost of acquisition the fair value of the shares issued by the company is taken to be the bid price of those shares at the date of the issue 
where this figure exceeds the nominal value of the shares the excess amount is treated as an addition to the merger reserve 
acquisitions on or after 1 january 2010
for acquisitions on or after 1 january 2010 the group measures goodwill at the acquisition date as
 i the fair value of the consideration transferred plus 
 i the recognised amount of any non‑controlling interests in the acquiree plus
 i the fair value of the existing equity interest in the acquiree less
 i the net recognised amount generally fair value of the identifiable assets acquired and liabilities assumed 
when the excess is negative a bargain purchase gain is recognised immediately in profit or loss
costs related to the acquisition other than those associated with the issue of debt or equity securities are expensed as incurred
any contingent consideration payable is recognised at fair value at the acquisition date if the contingent consideration is classified 
as equity it is not remeasured and settlement is accounted for within equity otherwise subsequent changes to the fair value of the 
contingent consideration are recognised in profit or loss
on a transaction‑by‑transaction basis the group elects to measure non‑controlling interests either at its fair value or at its proportionate 
interest in the recognised amount of the identifiable net assets of the acquiree at the acquisition date
acquisitions before 1 january 2010
for acquisitions which occurred before 1 january 2010 goodwill represents the excess of the cost of the acquisition over the group’s 
interest in the recognised amount generally fair value of the identifiable assets liabilities and contingent liabilities of the acquiree 
when the excess was negative a bargain purchase gain was recognised immediately in profit or loss
transaction costs other than those associated with the issue of debt or equity securities that the group incurred in connection with 
business combinations were capitalised as part of the cost of the acquisition 32 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
2 principal accounting policies continued
25 goodwill and other intangible assets
goodwill
goodwill is stated at cost less any accumulated impairment losses goodwill is allocated to cash‑generating units and is not amortised 
but is tested annually for impairment 
goodwill arising on the acquisition of a subsidiary represents the excess of the cost of acquisition over the group’s interest in the net 
fair value of the identifiable assets liabilities and contingent liabilities of the subsidiary at the date of acquisition goodwill is initially 
recognised as an asset at cost and is subsequently measured at cost less any accumulated impairment losses on disposal of 
a subsidiary the attributable amount of goodwill is included in the determination of the profit or loss on disposal 
other intangible assets
expenditure on internally generated goodwill and brands is recognised in the income statement as an expense as incurred
other intangible assets that are acquired by the group are stated at fair value less accumulated amortisation and less accumulated 
impairment losses 
amortisation
amortisation is charged to the income statement on a straight line basis over the estimated useful lives of intangible assets unless such 
lives are indefinite intangible assets with an indefinite useful life and goodwill are systematically tested for impairment at each balance 
sheet date other intangible assets are amortised from the date they are available for use the estimated useful lives are as follows
 i patents and trademarks 10–15 years
26 research and development
expenditure on research and development activities is recognised in the income statement as an expense as incurred
27 revenue recognition
the group’s income consists of licence fees milestone and option payments grant income and fees from research and development 
collaborations income is measured at the fair value of the consideration received or receivable
licence fees option and milestone payments are recognised in full on the date that they are contractually receivable in those 
circumstances where
 i the amounts are not time related 
 i the amounts are not refundable
 i the licensee has unrestricted rights to exploit the technology within the terms set by the licence and
 i the group has no further contractual duty to perform any future services 
where such fees or receipts require future performance or financial commitments on behalf of the group the revenue is recognised 
pro rata to the services or commitments being performed funds received that have not been recognised are treated as deferred 
revenue and recognised in trade and other payables
revenues from work or other research and testing carried out for third parties are recognised when the work to which they relate has 
been performed 
government grants are dealt with as per note 28 below
all time related receipts in respect of annual licence fees or similar technology access fees are recognised as revenue on a straight line 
basis over the period of the underlying contract
28 government grants
government grants towards the cost of staff employed in research and development activities are recognised as revenue over the periods 
necessary to match them with the related costs no grant revenue was recognised in the year ended 31 december 2011 2010 £334029
government grants towards the cost of plant and equipment are treated as a reduction in the cost of the asset to which they relate 
there were no such grants for the year ended 31 december 2011 2010 £nil
there were no unfulfilled conditions or contingencies attaching to these grants
29 foreign currency translation
silence therapeutics’ consolidated financial statements are presented in sterling £ which is also the functional currency of the parent 
company the individual financial statements of each group entity are presented in the currency of the primary economic environment 
in which the entity operates its functional currency silence therapeutics plc annual report and accounts 201 1 financial statements · 33
2 principal accounting policies continued
29 foreign currency translation continued
in preparing the financial statements of the individual entities transactions in currencies other than the entity’s functional currency foreign 
currencies are recorded at the rates of exchange prevailing on the dates of the transactions at each balance sheet date monetary items 
denominated in foreign currencies are retranslated at the rates prevailing on the balance sheet date non‑monetary items carried at fair 
value that are denominated in foreign currencies are retranslated at the rates prevailing on the date when the fair value was determined 
exchange differences arising on the settlement of monetary items and on the retranslation of monetary items are included in the profit 
or loss for the period when a gain or loss on a non‑monetary item is recognised directly in equity any exchange component of that 
gain or loss is also recognised directly in equity when a gain or loss on a non‑monetary item is recognised in profit or loss any 
exchange component of that gain or loss is also recognised in profit or loss 
for the purpose of presenting consolidated financial statements the assets and liabilities of the group’s foreign operations including 
comparatives are expressed in sterling using exchange rates prevailing on the balance sheet date income and expense items including 
comparatives are translated at the average exchange rates for the period exchange differences arising if any are recognised in equity 
cumulative translation differences are recognised in profit or loss in the period in which the foreign operation is disposed of
goodwill and fair value adjustments arising on the acquisition of a foreign operation are treated as assets and liabilities of the foreign 
operation and translated at the closing rate
210 defined contribution pension funds
the group pays contributions related to salary to certain uk employees’ individual pension schemes the pension cost charged against 
profits represents the amount of the contributions payable to the schemes in respect of the accounting period no separate provision 
is made in respect of non‑uk employees
211 property plant and equipment
the group holds no property assets
all plant and equipment is stated in the accounts at its cost of acquisition less a provision for depreciation
depreciation is charged to write off the cost less estimated residual values of plant and equipment on a straight line basis over their 
estimated useful lives all plant and equipment is estimated to have useful economic lives of between three and five years estimated 
useful economic lives and residual values are reviewed each year and amended if necessary
212 other intangible assets and research and development activities
intellectual property rights
other intangible assets include both acquired and internally developed intellectual property used in research and operations these 
assets are stated at cost less amortisation 
acquired intellectual property rights are capitalised on the basis of the costs incurred to acquire the specific rights
internally generated intellectual property rights are recognised as intangible assets stated at cost incurred to establish and maintain 
those rights and are subject to the same subsequent measurement method as externally acquired intellectual property however until 
completion of the development project the assets are subject to impairment testing only as described below amortisation commences 
upon completion of the asset costs capitalised relate to patent prosecution expenses paid to third parties
amortisation is applied to write off the cost less residual value of the intangible assets on a straight line basis over their estimated useful 
life the principal rates used are 67 and 10 per annum amortisation is included within research and development costs
capitalisation of research and development costs
costs associated with research activities are treated as an expense in the period in which they are incurred
costs that are directly attributable to the development phase of an internal project will only be recognised as intangible assets provided 
they meet the following requirements
 i an asset is created that can be separately identified
 i the technical feasibility exists to complete the intangible asset so that it will be available for sale or use and the group has the 
intention and ability so to do
 i it is probable that the asset created will generate future economic benefits either through internal use or sale
 i sufficient technical financial and other resources are available for completion of the asset and
 i the expenditure attributable to the intangible asset during its development can be reliably measured
careful judgement by the group’s management is applied when deciding whether recognition requirements for development costs have 
been met this is necessary as the economic success of any product development is uncertain and may be subject to future technical 
problems at the time of recognition judgements are based on the information available at each balance sheet date  34 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
2 principal accounting policies continued
212 other intangible assets and research and development activities continued
capitalisation of research and development costs continued
to date no development costs have been capitalised in respect of the internal projects other than costs directly associated with arising 
intellectual property rights on the grounds that the costs to date are either for the research phase of the projects or if relating to the 
development phase then the work so far does not meet the recognition criteria set out above 
213 impairment testing of goodwill other intangible assets and property plant and equipment
at each balance sheet date the group assesses whether there is any indication that the carrying value of any asset may be impaired 
if any such indication exists the recoverable amount of the asset is estimated in order to determine the extent of the impairment loss 
if any where it is not possible to estimate the recoverable amount of an individual asset the group estimates the recoverable amount 
of the cash‑generating unit to which the asset belongs
in the case of goodwill and any intangible asset with either an indefinite useful life or which is not yet available for use the group tests 
for impairment at each balance sheet date
for the purposes of assessing impairment assets are grouped at the lowest levels for which there are separately identifiable cash flows 
cash‑generating units goodwill is allocated to those cash‑generating units that are expected to benefit from synergies of the related 
business combination and represent the lowest level within the group at which management controls the related cash flows
individual assets or cash‑generating units that include goodwill and other intangible assets with an indefinite useful life or those not yet 
available for use are tested for impairment at least annually all other individual assets or cash‑generating units are tested for impairment 
whenever events or changes in circumstances indicate that the carrying amount may not be recoverable
an impairment loss is recognised for the amount by which the asset’s or cash‑generating unit’s carrying amount exceeds its recoverable 
amount the recoverable amount is the higher of fair value reflecting market conditions less costs to sell and value in use based on an 
internal discounted cash flow evaluation impairment losses recognised for cash‑generating units to which goodwill has been allocated 
are credited initially to the carrying amount of goodwill any remaining impairment loss is charged pro rata to the other assets in the 
cash‑generating unit 
214 investments in subsidiaries
investments in subsidiaries comprise shares in the subsidiaries and loans from the company investment in shares of the subsidiaries 
are stated at cost less provisions for impairment recognition and subsequent measurement is at amortised cost 
215 financial instruments
financial assets and financial liabilities are recognised on the group’s balance sheet when the group becomes a party to the 
contractual provisions of the instrument
financial assets can be divided into the following categories loans and receivables financial assets at fair value through profit or loss 
available‑for‑sale financial assets and held‑to‑maturity investments financial assets are assigned to the different categories by management 
on initial recognition depending on the purpose for which the instruments were acquired the designation of financial assets is re‑evaluated 
at every reporting date at which a choice of classification or accounting treatment is available
de‑recognition of financial instruments occurs when the rights to receive cash flows from investments expire or are transferred and 
substantially all of the risks and rewards of ownership have been transferred an assessment for impairment is undertaken at least 
at each balance sheet date whether or not there is objective evidence that a financial asset or a group of financial assets is impaired
trade receivables
trade receivables are measured at initial recognition at fair value plus if appropriate directly attributable transaction costs and are 
subsequently measured at amortised cost using the effective interest method appropriate allowances for estimated irrecoverable 
amounts are recognised in profit or loss when there is objective evidence that the asset is impaired the allowance recognised is 
measured as the difference between the asset’s carrying amount and the present value of estimated future cash flows discounted 
at an effective interest rate computed at initial recognition 
loans receivable
loans receivable are non‑derivative financial assets with fixed or determinable payments that are not quoted in an active market they 
arise when the group or company provides money directly to a debtor with no intention of trading the receivables loans receivable are 
measured at initial recognition at fair value plus if appropriate directly attributable transaction costs and are subsequently measured at 
amortised cost using the effective interest method less provision for impairment any change in their value is recognised in profit or loss
cash and cash equivalents
cash and cash equivalents comprise cash on hand and demand deposits that are readily convertible to a known amount of cash and 
are subject to an insignificant risk of change in value silence therapeutics plc annual report and accounts 201 1 financial statements · 35
2 principal accounting policies continued
215 financial instruments continued
financial liabilities and equity
financial liabilities and equity instruments issued by the group are classified according to the substance of the contractual 
arrangements entered into and the definitions of a financial liability and an equity instrument a financial liability is a contractual 
obligation to either deliver cash or another financial asset to another entity or to exchange a financial asset or financial liability with 
another entity including obligations which may be settled by the group using its equity instruments an equity instrument is any contract 
that evidences a residual interest in the assets of the group after deducting all of its liabilities the accounting policies adopted for 
specific financial liabilities and equity instruments are set out below
financial liabilities
at initial recognition financial liabilities are measured at their fair value plus if appropriate any transaction costs that are directly 
attributable to the issue of the financial liability after initial recognition all financial liabilities are measured at amortised cost using the 
effective interest method
equity instruments
equity instruments issued by the group are recorded at the proceeds received net of direct issue costs
216 operating leases
leases where substantially all the risks and rewards of ownership remain with the lessor are treated as operating leases and are 
accounted for on a straight line basis over the term of the lease and charged to the income statement
217 provisions
provisions are recognised when the group has a present obligation as a result of a past event and it is probable that the group will be 
required to settle that obligation provisions are measured at the directors’ best estimate of the expenditure required to settle the 
obligation at the balance sheet date and are discounted to present value where the effect is material
218 share‑based payments
the group issues equity‑settled share‑based payments to certain employees and advisers equity‑settled share‑based payments are 
measured at fair value excluding the effect of non market‑based vesting conditions at the date of grant the fair value so determined is 
expensed on a straight line basis over the vesting period based on the group’s estimate of the number of shares that will eventually vest 
and adjusted for the effect of non market‑based vesting conditions the value of the change is adjusted to reflect expected and actual 
levels of award vesting except where failure to vest is as a result of not meeting a market condition cancellations of equity instruments 
are treated as an acceleration of the vesting period and any outstanding charge is recognised in full immediately fair value is measured 
using a binomial pricing model the key assumptions used in the model have been adjusted based on management’s best estimate 
for the effects of non‑transferability exercise restrictions and behavioural considerations 
219 equity 
share capital is determined using the nominal value of shares that have been issued
the share premium account includes any premiums received on the initial issuing of the share capital any transaction costs associated 
with the issuing of shares are deducted from the share premium account net of any related income tax benefits
the merger reserve represents the difference between the nominal value and the market value at the date of issue of shares issued 
in connection with the acquisition by the group of an interest in over 90 of the share capital of another company
equity‑settled share‑based payments are credited to a share‑based payment reserve as a component of equity until related options 
or warrants are exercised
foreign currency translation differences are included in the translation reserve
retained loss includes all current and prior period results as disclosed in the income statement
220 taxation
the tax credit recognised in the income statement represents the sum of the tax currently payable or receivable and deferred tax
the tax currently payable is based on taxable profit for the year taxable profit differs from profit as reported in the income statement 
because it excludes items of income or expense that are taxable or deductible in other years and it further excludes items that are never 
taxable or deductible the group’s liability for current tax is calculated using tax rates that have been enacted or substantively enacted 
by the balance sheet date
tax receivable arises from the uk legislation regarding the treatment of certain qualifying research and development costs allowing 
for the surrender of tax losses attributable to such costs in return for a tax rebate 36 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
2 principal accounting policies continued
220 taxation continued
deferred tax is recognised on differences between the carrying amounts of assets and liabilities in the financial statements and the 
corresponding tax bases used in the computation of taxable profit and is accounted for using the balance sheet liability method deferred 
tax liabilities are generally recognised for all taxable temporary differences and deferred tax assets are recognised to the extent that it is 
probable that taxable profits will be available against which deductible temporary differences can be utilised such assets and liabilities 
are not recognised if the temporary difference arises from initial recognition of goodwill or from the initial recognition other than in 
a business combination of other assets and liabilities in a transaction that affects neither the taxable profit nor the accounting profit
deferred tax liabilities are recognised for taxable temporary differences arising on investments in subsidiaries and associates and 
interests in joint ventures except where the group is able to control the reversal of the temporary difference and it is probable that the 
temporary difference will not reverse in the foreseeable future
the carrying amount of deferred tax assets is reviewed at each balance sheet date and reduced to the extent that it is no longer 
probable that sufficient taxable profits will be available to allow all or part of the asset to be recovered
deferred tax is calculated at the tax rates that are expected to apply in the period when the liability is settled or the asset realised deferred 
tax is charged or credited to profit or loss except when it relates to items charged or credited directly to equity in which case the deferred 
tax is also dealt with in equity
deferred tax assets and liabilities are offset when there is a legally enforceable right to set off current tax assets against current tax 
liabilities and when they relate to income taxes levied by the same taxation authority and the group intends to settle its current tax 
assets and liabilities on a net basis
221 critical accounting judgements and key sources of estimation uncertainty
in the process of applying the entity’s accounting policies management makes estimates and assumptions that have an effect on the 
amounts recognised in the financial statements although these estimates are based on management’s best knowledge of current 
events and actions actual results may ultimately differ from those estimates
the key assumptions concerning the future and other key sources of estimation uncertainty at the balance sheet date that have a significant 
risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are those relating to 
 i the capitalisation or otherwise of development expenditure
 i the ability of the group to operate as a “going concern”
 i the carrying value of the company’s investment in its subsidiaries
 i the future recoverability of goodwill and other intangible assets and 
 i the corresponding review for impairment of those assets
the group expends considerable sums on its development projects with its total research and development costs for 2011 amounting to 
£3360442 2010 £5821212 the board has decided not to capitalise any development costs to date as it would not be able to prove reliably 
that such costs could be recovered due to the risk factors involved therefore all such costs have been treated as expenses as they were 
incurred any decision to treat part of those costs as capital items could have a significant impact on the group’s results and balance sheet 
as explained in note 23 above the accounts are drawn up on the going concern basis which assumes that the group will be able to 
access sufficient funds to continue to operate for the foreseeable future if the accounts were to be drawn up on the basis that this 
assumption was not valid then there could be material changes to the carrying values of both assets and liabilities
the group’s main activities are carried out by subsidiary companies which are financed by ongoing investment by the parent company 
these investments are carried in the books of the parent company at cost less provisions for impairment the carrying value at 31 
december 2011 is £54217931 2010 £50615307 the key assumptions concerning the carrying value of the investments in and loans 
to subsidiaries relate to the continuing progress of the research and development programmes 
as noted below there are a number of risks and uncertainties around those assumptions and the crystallisation of any of those risks 
could have a significant impact on the assessment of the carrying value of the investment shown in the accounts of the parent company
goodwill is carried in the accounts at a value of £28342109 at 31 december 2011 2010 £28346276 
other intangible assets have a carrying value at 31 december 2011 of £971154 2010 £945391 and details of the movement in the year 
the capitalisation and amortisation policy and the basis of the impairment review are set out in note 13
the key assumptions concerning the carrying value or otherwise for both the goodwill and other intangible assets relate to the 
continuing progress of the group’s research and development programmes which are subject to risks common to all biotechnology 
businesses these risks include the impact of competition in the specific areas of development the potential failure of the projects in 
development or clinical trials and the possible inability to progress projects due to regulatory manufacturing or intellectual property 
issues or the lack of available funds or other resources furthermore the crystallisation of any of these risks could have a significant 
impact on the assessment of the value of both goodwill and other intangible assets silence therapeutics plc annual report and accounts 201 1 financial statements · 37
3 revenue
revenue in the year was from licence fees generated by both european and us operations the analysis of revenues by geographical 
destination is
2011
£
2010
£
europe 503519 711572
north america 14018 655513
asiapacific 176018 998792
693555 2365877
revenue is earned from milestones £nil 2010 £407628 licence fees £693555 2010 £1624220 and grants £nil 2010 £334029
4 segment reporting
in 2011 the group operated in the specific technology fields of rnai therapeutics and immunotherapy although the immunotherapy 
business has now almost entirely ceased operations these activities were carried out in separate operating subsidiaries with certain 
centralised functions carried out at group level these are the three reporting areas used by the board in its management of the entity 
and as such are the group’s reportable segments
due to the nature of its licensing activities the group’s revenues in any one year often derive from a small number of customers that 
change year by year during 2011 £473036 or 68 of group revenues arose from a single customer with £176018 25 coming from 
a second customer during 2010 the comparative figures for those two customers were £533037 23 and £998792 42 respectively
in 2011 non‑current assets situated in the us uk and germany were £21224323 2010 £20897053 £3313 2010 £nil and £8310607 
2010 £8682227 respectively 
segment profit used by the board in its assessment of the entity is profit before tax
business segments
2011
rnai
therapeutics
£
immunotherapy
£
group
unallocated
£
total
£
revenue from external customers 693555 — — 693555
operating loss 4821382 715 963804 5785901
interest income 32030 — 24616 56646
interest expense 12817 — — 12817
gain on sale of assets 5509 — — 5509
segment loss for the year before taxation 4796660 715 939188 5736563
segment assets 30032362 — 3405510 33437872
segment liabilities 1078098 — 181886 1259984
costs to acquire property plant and equipment 23305 — 3587 26892
costs to acquire intangible assets 247586 — — 247586
depreciation and amortisation 304659 — 274 304933
income tax — — — —
charge for non‑cash expenses share‑based payments charge 93154 — 27320 120474
segment non‑current assets 29534930 — 3313 29538243 38 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
4 segment reporting continued
business segments continued
2010
rnai 
therapeutics
£
immunotherapy
£
group
unallocated
£
total
£
revenue from external customers 2365877 — — 2365877
operating loss 6318992 19434 2319847 8658273
interest income 26283 46427 22633 95343
interest expense 61231 94 1970 63295
gainloss on sale of assets 169049 — — 169049
segment lossprofit for the year before taxation 6522990 26899 2299183 8795274
segment assets 31621394 5471 2329326 33956191
segment liabilities 1428671 8000 249845 1686516
costs to acquire property plant and equipment 30834 — — 30834
costs to acquire intangible assets 259980 — — 259980
depreciation and amortisation 322016 1277 — 323293
income tax — — — —
charge for non‑cash expenses share‑based payments charge 391571 — 267447 659018
segment non‑current assets 29579280 — — 29579280
the operations segment assets and liabilities of the rnai therapeutics segment are located in germany and the us the operations 
segment assets and liabilities of the remaining two segments are located in the uk 
5 operating loss 
this is stated after charging
2011
£
2010
£
depreciation of property plant and equipment 91355 141689
amortisation of intangibles 213578 181604
restructuring expenses 471825 —
share‑based payments charge 121269 659018
auditors’ remuneration
 – group audit fee – kpmg audit plc 48000 40000
 – group audit fee overruns– kpmg audit plc — 15000
 – audit of subsidiaries pursuant to legislation 17000 25000
 – taxation 11000 11000
 – other services pursuant to legislation — 2500
operating lease payments on offices 288376 546181
fees payable to auditors other than the auditors of the company amounted to £nil 2010 £nil
taxation services consist of tax compliance services no information on auditor remuneration in respect of the company has been given 
as the group accounts are required to give on a group basis the disclosures required by regulation
silence streamlined and reorganised its operations to increase efficiency and reduce cash spend as part of this the facility in redwood 
city california was closed which resulted in severance payments totalling £421745 in addition headcount in some non‑critical roles 
was reduced in berlin £50080 and the non‑executive board membership was also reduced
6 directors and staff costs
staff costs including directors’ remuneration during the year were as follows
2011
£
2010
£
wages and salaries 2257867 3531703
termination benefits 471825 867676
social security costs 322612 638555
charge in respect of share‑based payments 121269 659018
pension costs 18000 16375
3191573 5713327 silence therapeutics plc annual report and accounts 201 1 financial statements · 39
6 directors and staff costs continued
the average number of employees including both executive and non‑executive directors during the year was 37 2010 49 
excluding the directors the average number of employees of the parent company was 1 2010 1
management remuneration paid and other benefits supplied to the directors during the year were as follows
salary 
and fees
1
£
monetary 
value of 
benefits
2
£
termination 
pay
£
2011 total 
excluding 
pension
£
2011 
pensions
£
2010 total 
excluding 
pensions
£
2010 
pensions
£
p haworth 124910 4121 207024 336055 — 189676 —
j a p randall 60000 — — 60000 — 55000 —
m herrmann 180000 89 — 180089 18000 120000 12000
j m davies — — — — — 297508 4375
t christély 64239 — — 64239 — — —
a clancy 30000 — — 30000 — 30000 —
d c u’prichard 30000 — — 30000 — 30000 —
i g ross — — — — — 255200 —
j l curnock cook — — — — — 15000 —
h r p reynolds — — — — — 15000 —
b o wetzel — — — — — 15000 —
489149 4210 207024 700383 18000 1022384 16375
1  no bonuses will be paid to directors in respect of the year ended 31 december 2011
2  executive directors’ benefits include private health insurance
details of share options granted to directors are detailed in note 19
the directors of the group are the same as the key management personnel as defined by ias 24 “related party transactions” 
7 finance income
the finance income comprises
2011
£
2010
£
bank interest receivable 26764 37565
gain on security held for resale 29882 —
exchange differences — 57778
total 56646 95343
8 taxation
2011
£
2010
£
loss per accounts 5736563 8795274
tax credit at the standard rate of uk corporation tax of 26 2010 28 1491506 2462677
effect of overseas tax rate germany and us 312613 430853
impact of costs disallowable for tax purposes 113208 489261
impact of income not taxable — 50117
deferred tax in respect of temporary differences — 711
impact of unrelieved tax losses not recognised 1690911 2354863
sub‑total — —
adjustment to that relief in respect of prior periods — —
taxation credit for the year — —
estimated tax losses of £764m 2010 £723m are available for relief against future profits
the deferred tax asset not provided for in the accounts based on the estimated tax losses and the treatment of the equity‑settled 
share‑based payments net of any other temporary differences is approximately £255m 2010 £248m
the 2012 budget on 21 march 2012 announced that the uk corporation tax rate will reduce to 22 by 2014 a reduction in the rate from 
26 to 25 effective from 1 april 2012 was substantially enacted on 5 july 2011 and a further reduction to 24 effective from 1 april 2012 
is expected to be substantively enacted by the end of march 2012 40 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
9 loss per share
the calculation of the loss per share is based on the loss for the financial year after taxation of £5736563 2010 £8795274 and on 
the weighted average of 466864698 2010 278303966 ordinary shares in issue during the year 
the options outstanding at 31 december 2011 and 31 december 2010 are considered to be non‑dilutive in that their conversion into 
ordinary shares would not increase the net loss per share consequently there is no diluted loss per share to report for either year
10 business combinations
there were no business combinations in 2011
acquisitions in the prior period 
on 5 january 2010 the company acquired the entire issued share capital of intradigm corporation a company also engaged in 
the development of rnai‑based therapeutics by issuance of 79640668 ordinary shares representing consideration of £16903732 
the fair value of each share was 21225 pence based on the average mid‑price of the shares over the preceding ten days additional 
consideration for the acquisition included 1138817 immediately vesting options which were issued to executives of intradigm on 
completion of the deal
the total cost of acquisition includes the components stated below
 £
purchase price settled in shares 16903732
value of options issued to intradigm executives 101035
total cost of acquisition 17004767
the carrying amount and fair value of the assets and liabilities acquired are as follows
carrying amount
£
fair value
£
property plant and equipment 265744 265744
other intangible assets — 162622
trade and other receivables 169450 169450
cash and short‑term deposits 746108 746108
trade and other payables 2151095 2151087
short‑term borrowings 1876407 1876407
deferred revenue 423142 423142
fair value of net liabilities acquired 3106712
goodwill arising on acquisition 20111479
total cost of acquisition 17004767
the carrying value of goodwill arising on acquisition reflects the position intradigm occupies in the high profile field of rnai therapeutics 
the synergies expected to arise from combination with the company already a leader in the field and the strengthened management 
team resulting from the acquisition
reconciliation of goodwill
£
goodwill brought forward at 1 january 2010 8130972
goodwill on acquisition 20111479
translation adjustment 103825
total 28346276
if the acquisition had been completed on the first day of the financial year no significant additional revenue and no significant operating 
loss would have been recognised in the group results the inclusion of intradigm corporation from 5 january 2010 to 31 december 
2010 contributed £239395 to revenues and £3469368 to the net loss of the group silence therapeutics plc annual report and accounts 201 1 financial statements · 41
10 business combinations continued
reconciliation of goodwill continued
acquisition related costs
in 2010 the group incurred acquisition related costs of £70000 related to the merger with intradigm corporation these costs have 
been included in administrative expenses in the group’s consolidated statement income statement
issue of shares in conjunction with the intradigm acquisition
in conjunction with the acquisition of intradigm on 5 january 2010 the company raised £1436m in cash net of expenses the fundraising 
was conducted by way of a placing and subscription of 65217392 new ordinary shares of 1p each at a price of 23p per share the nominal 
value of these shares was £652174
repayment of loan
on 4 june 2010 the group repaid all amounts outstanding on its short‑term loan with silicon valley bank the loan had been taken out 
by intradigm prior to its acquisition by silence and was due for repayment on 31 december 2010
11 property plant and equipment
group
equipment
and furniture
total
£
cost
at 1 january 2010 3718676
additions through business combinations 719348
additions 30834
disposals 752975
translation adjustment 147940
at 31 december 2010 3567943
additions 26892
disposals 156643
translation adjustment 130994
at 31 december 2011 3307198
depreciation
at 1 january 2010 3342000
acquisition of intradigm 453604
charge for the year 141689
eliminated on disposal 517458
translation adjustment 139505
at 31 december 2010 3280330
charge for the year 91355
eliminated on disposal 164332
translation adjustment 125135
at 31 december 2011 3082218
net book value 
as at 31 december 2010 287613
as at 31 december 2011 224980 42 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
11 property plant and equipment continued
company
equipment
and furniture
total
£
cost
at 1 january 2010 —
at 31 december 2010 —
additions 3587
disposals —
translation adjustment —
at 31 december 2011 3587
depreciation
at 1 january 2010 —
at 31 december 2010 —
charge for the year 274
eliminated on disposal —
translation adjustment —
at 31 december 2011 274
net book value 
as at 31 december 2010 —
as at 31 december 2011 3313
12 goodwill
the carrying amount of goodwill is attributable to the acquisition of silence therapeutics ag in 2005 and intradigm corporation in 2010
2011
£
2010
£
balance at start of year 28346276 8130972
acquisition of intradigm — 20111479
translation adjustment 4167 103825
balance at end of year 28342109 28346276
in accordance with ias 36 “impairment of assets” the carrying value of goodwill has been assessed comparing its carrying value to its 
net recoverable amount the recoverable amount has been calculated by the directors as being the value in use 
to arrive at value in use the directors have performed risk‑adjusted discounted cash flow analysis of the rnai therapeutics business 
area the cash‑generating unit that encompasses silence therapeutics ag and intradigm corporation based on the net present value 
of these discounted cash flows the board considers there is no need to impair the carrying value of goodwill the acquisition of intradigm 
in 2010 resulted in additional goodwill of £20111479 being recognised by the group at 31 december 2011 the carrying amount of goodwill 
relating to intradigm and silence therapeutics ag was £20811801 2010 £20594526 and £7530308 2010 £7751750 respectively 
the directors believe that this amount of goodwill is supported by the future potential of the rnai therapeutics business area as described 
above the enlarged group is one of the strongest players in the rnai therapeutics arena the directors believe that significant synergies 
have been created by combining the strength of silence’s intellectual property in structural chemistry aturnai with intradigm’s exclusive 
licence to the “zamore design rules” from the university of massachusetts therefore the group is now better placed to secure licensing 
revenue from pharmaceutical partners silence therapeutics plc annual report and accounts 201 1 financial statements · 43
12 goodwill continued
the recoverable amount of the rnai therapy business has been calculated with reference to its value in use the key assumptions 
of this calculation are shown below
2011
period on which management approved forecasts are based 2022
growth rate applied beyond approved forecast period na
discount rate 9
terminal valuation multiple priceearnings 15x
probability of success of phase i compound 10
probability of success of phase ii compound 20
management have used an approved forecast period of greater than five years because of the long‑term nature of revenue streams from 
clinical development stage pharmaceutical drug candidates 
the terminal valuation used is based on the current average priceearnings ratio for profitable biotechnology companies 
the discount rate used is based on the current discount rate used by professionals to value publicly traded equities and corporate 
market‑specific risk silence has applied industry standard attrition rates to risk adjust products in clinical development 
sensitivity analysis has been conducted on both the discount rate and sales assumptions used to calculate the net present value ‘npv’ 
of the rnai therapeutics business area a 25 reduction in sales estimates for all products in development still left an npv in excess 
of the carrying value of the business area as did an increase in the discount rate used to 108 
13 other intangible assets
 
licences
£
internally generated
patents and patent 
applications
£
total
£
cost
at 1 january 2010 2488383 1012510 3500893
additions acquired through business combinations 162622 — 162622
additions 152005 107975 259980
translation adjustment 113640 47260 160900
at 31 december 2010 2689370 1073225 3762595
additions 133956 113630 247586
translation adjustment 73344 35416 108760
at 31 december 2011 2749982 1151439 3901421
amortisation
at 1 january 2010 2415680 349096 2764776
charge for the year 53995 127609 181604
translation adjustment 112892 16284 129176
at 31 december 2010 2356783 460421 2817204
charge for the year 56469 157109 213578
translation adjustment 80873 19642 100515
at 31 december 2011 2332379 597888 2930267
net book value 
as at 31 december 2010 332587 612804 945391
as at 31 december 2011 417603 553551 971154
the licences included above have finite useful lives estimated to be of 10–14 years from date of initial acquisition over which period 
the assets are amortised the group’s internally generated patent costs above represent expenses connected with filings for patent 
registration in respect of technology that has been developed by the group for use in revenue‑generating activities these costs are 
amortised on a straight line basis over 10–14 years commencing upon the completion of the relevant asset the charge for amortisation 
is included within research and development costs in the income statement  44 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
13 other intangible assets continued
the group tests for impairment of definite lives intangible assets on a regular basis if indicators of impairment exist such as a change 
of use of the asset a reduction in operating cash flow or a change in technology the company compares the discounted cash flows 
related to the asset to the carrying value of the asset if the carrying value is greater than the discounted cash flow amount an impairment 
charge is recorded for the amount necessary to reduce the carrying value of the asset to fair value fair value for the purpose of the 
impairment tests is determined based on current market value or discounted future cash flows in determining the fair value certain 
assumptions are made concerning for example estimated cash flow and growth of the group’s operations 
the zamore intellectual property assets have been valued based on a risk‑adjusted estimate of future discounted cash flows 
at 31 december 2011 the zamore intellectual property assets had a net book value of £412521 2010 £299680 additional other 
intangible assets include intellectual property relating to atuplex and aturnai technologies which are already the subject of commercial 
licences these technologies have been valued based on estimated future discounted cash flows and had a net book value of £558633 
2010 £645711 in 2011 there were no other intangible assets in the company 2010 £nil
14 investments
company
2011
£
2010
£
investment in subsidiary undertakings 54217931 50615307
the investment in subsidiary undertakings is made up as follows
investment
at cost
£
impairment
provision
£
net
total
£
shares in subsidiary undertakings
at 1 january 2010 23066349 205477 22860872
additions 23731737 2477 23734214
at 31 december 2010 46798086 203000 46595086
additions 691201 — 691201
at 31 december 2011 47489287 203000 47286287
loans to subsidiary undertakings
at 1 january 2010 23189465 22555855 633610
reductions 3236753 149858 3386611
at 31 december 2010 26426218 22405997 4020221
additions 2914665 3242 2911423
at 31 december 2011 29340883 22409239 6931644
total investment 
as at 31 december 2010 73224304 22608997 50615307
as at 31 december 2011 76830170 22612239 54217931
at 31 december 2011 a non‑interest bearing unsecured loan of £22409235 from silence therapeutics plc to stanford rook ltd was 
outstanding 2010 £22405997 this has been fully provided for in both 2010 and 2011 a further subordinated 5 interest‑bearing loan 
of £6931644 from silence therapeutics to silence therapeutics ag was outstanding 2010 £4020221
subsidiary companies
the principal activity of all subsidiaries is the research and development of pharmaceutical products
name
place of incorporation
and operation principal technology area
proportion of
ownership
interest
silence therapeutics ag germany rnai therapeutics 100
intradigm corporation us rnai therapeutics 100
stanford rook ltd england immunotherapy 100
innopeg ltd england not active 100
the company has made additional investments during the year in its operating subsidiaries silence therapeutics ag and intradigm 
corporation silence therapeutics plc has made an impairment provision against the investment and loans to stanford rook limited 
and innopeg limited to the extent that they are deemed to be not recoverable no impairment provision has been made against the 
investment in silence therapeutics ag or intradigm corporation as the directors believe that the fair value exceeds the cost of 
investment to date silence therapeutics plc annual report and accounts 201 1 financial statements · 45
15 trade and other receivables
group
2011
£
company
2011
£
group
2010
£
company
2010
£
trade receivables 35894 — 597952 —
other receivables 28721 33280 96732 18102
prepayments 109731 46212 87912 27922
174346 79492 782596 46024
the directors consider that the carrying amount of trade and other receivables approximates to their fair value trade and other receivables 
were all payable within 90 days fair values have been calculated by discounting cash flows at prevailing interest rates see also note 25
no interest is charged on outstanding trade receivables
16 cash and cash equivalents
group
2011
£
company
2011
£
group
2010
£
company
2010
£
cash at bank 3687860 3322705 3566877 2283300
cash at bank comprises balances held by the group in current and short‑term bank deposits with a maturity of three months or less 
the carrying amount of these assets approximates to their fair value the deposits held at bank are treated as cash equivalents under 
the definitions of ias 7 “cash flow statements” 
although the sums are in a short‑term notice account they are instantly available to the group but only by breaking the terms of the 
deposit which may incur a minor loss of interest during the year the effective rate of interest in notice accounts was 075 per annum
17 trade and other payables 
group
2011
£
company
2011
£
group
2010
£
company
2010
£
trade payables 450187 85237 345785 38441
social security and other taxes — 19538 8644 8644
deferred revenues 392321 — 556105 —
accruals and other payables 417476 77110 775982 202761
1259984 181885 1686516 249846
trade payables accruals and other payables principally comprise amounts outstanding for trade purchases and continuing costs 
the directors consider that the carrying amount of trade and other payables approximates to their fair value fair values have been 
calculated by discounting cash flows at prevailing interest rates see also note 25
18 deferred taxation
the following are the major deferred tax liabilities and assets recognised by the group
2011
£
2010
£
deferred tax liability 
 – in respect of intangible assets 327000 310000
liability 327000 310000
less offset of deferred tax asset below 327000 310000
2011
£
2010
£
deferred tax asset
 – in respect of available tax losses 24390000 23620000
 – in respect of share‑based payments 1136000 1130000
deferred tax asset 25526000 24750000
less offset against deferred tax liability 327000 310000
 provision against asset 25199000 24440000
asset — —
due to the uncertainty of future profits no deferred tax asset was recognised at 31 december 2011 2010 £nil 46 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
19 share capital
2011
£
2010
£
allotted called up and fully paid 
577114517 2010 279891452 ordinary shares par value £001 per share 5771145 2798915
the group has only one class of share all ordinary shares have equal voting rights and rank pari passu for the distribution of dividends 
and repayment of capital
details of the shares issued by the company during the current and previous years are as follows
£
number of shares in issue at 1 january 2010 135033392
shares issued during 2010
 – issue of shares for cash at 23p per share 65217392
 – issue of shares to acquire entire issued share capital of intradigm at 21225p per share 79640668
total issued in year 144858060
number of shares in issue at 31 december 2010 279891452
shares issued during 2011
 – issue of shares for cash at 2p per share 296693065
 – issue of shares at 236p per share 530000
total issued in year 297223065
number of shares in issue at 31 december 2011 577114517
the group operates both an inland revenue approved share option scheme and an unapproved share option scheme all directors 
and uk employees are eligible for both schemes the group has also granted options to certain directors and employees under the 
auspices of an enterprise management incentive scheme 
at 31 december 2011 there were options outstanding over 41762447 2010 24674843 unissued ordinary shares and 462963 warrants 
outstanding 2010 nil over unissued ordinary shares 
details of the options outstanding are as follows
exercise date number 
exercise 
price
at any time up to 24 july 2015 2550000 2300p
at any time up to 25 july 2016 594918 1275p
at any time up to 23 november 2016 600000 4300p
at any time up to 29 may 2017 80000 10900p
at any time up to 26 july 2017 1000000 12700p
at any time up to 14 december 2017 80000 6775p
at any time up to 6 may 2018 53333 4150p
between 7 may 2011 and 6 may 2018 51666 4150p
at any time up to 25 september 2018 410000 2950p
between 26 september 2011 and 25 september 2018 5000 2950p
at any time up to 4 december 2018 2026662 2000p
between 5 december 2011 and 4 december 2018 1013336 2000p
at any time up to 4 january 2020 1853777 2123p
between 5 january 2011 and 4 january 2020 859378 2123p
between 5 january 2012 and 4 january 2020 859377 2123p
between 16 may 2011 and 16 may 2021 675001 207p
between 1
 
june 2012 and 16 may 2021 675000 207p
between 1
 
june 2013 and 16 may 2021 674999 207p
between 13 october 2012 and 13 october 2021 8233337 180p
between 13 october 2013 and 13 october 2021 8233332 180p
between 13 october 2014 and 13 october 2021 8233331 180p
between 24 october 2012 and 24 october 2021 1000001 217p
between 24 october 2013 and 24 october 2021 1000000 217p
between 24 october 2014 and 24 october 2021 999999 217p
total 41762447 —
the options held by the directors at the beginning and end of the year are as detailed below no director exercised options during 2011  silence therapeutics plc annual report and accounts 201 1 financial statements · 47
19 share capital continued
director
at 1 january
2011
lapsed in
the year
at 31 december
2011
exercise 
price
latest date
of exercise
d c u’prichard
 – unapproved scheme 250000 — 250000 2300p 24072015
 – unapproved scheme 350000 — 350000 2000p 04122018
a clancy
 – unapproved scheme 200000 — 200000 2950p 25092018
j a p randall
 – unapproved scheme 200000 — 200000 2950p 25092018
p haworth
 – unapproved scheme 1325000 — 1325000 2123p 04012020
t christély
 – unapproved scheme 1300000 — 1300000 2300p 24072015
 – unapproved scheme 200000 — 200000 4300p 24112016
 – unapproved scheme 500000 — 500000 12700p 26072017
 – unapproved scheme 750000 — 750000 2000p 05122018
 – unapproved scheme 300000 — 300000 2123p 05012020
 – unapproved scheme —  — 9100000 180p 13102021
m herrmann 
 – unapproved scheme — — 1700000 207p 16052021
 – approved scheme — — 1666666 180p 13102021
 – unapproved scheme — — 1633334 180p 13102021
total 5375000 — 19475000 — —
upon the close of the merger with intradigm certain silence therapeutics directors were asked to step down as part of their separation 
letters these directors were made eligible under the plan to exercise their share options through 31 december 2011
none of the options granted under any of the schemes have any future performance or qualifying conditions attached to them other 
than remaining as an employee the remuneration committee did not believe that the inclusion of such conditions for staff or directors 
was appropriate at the time of granting these options
the market price of the shares at the year end was 206p per share 31 december 2010 779p 
during the year the minimum and maximum prices were 150p and 815p per share respectively
at 31 december 2011 the group had outstanding warrants over 462963 shares that were convertible at 2700p per share to be exercised 
before 24 july 2013 2010 nil 48 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
20 capital reserves
group
share
premium
account
£
merger
reserve
£
share‑based
payment
reserve
£
total
£
at 1 january 2010 40483306 6140874 3185891 49810071
on shares issued in the year 14347826 16107325 — 30455151
 – less costs of share issue 641687 — — 641687
on options in issue during the year — — 760053 760053
on vested options lapsed during the year — — 2477 2477
on vested warrants lapsed during the year — — 111833 111833
movement in the year 13706139 16107325 645743 30459207
at 31 december 2010 54189445 22248199 3831634 80269278
on shares issued in the year 2974121 — — 2974121
 – less costs of share issue 427316 — — 427316
on options in issue during the year — — 120474 120474
on vested options lapsed during the year — — 1795928 1795928
on issued warrants during the year — — 795 795
movement in the year 2546805 — 1674659 872146
at 31 december 2011 56736250 22248199 2156975 81141424
company
share
premium
account
£
merger
reserve
£
share‑based
payment
reserve
£
total
£
at 1 january 2010 40483306 5956958 3185891 49626155
on shares issued in the year 14347826 16107325 — 30455151
 – less costs of share issue 641687 — — 641687
on options in issue during the year — — 760053 760053
on options exercised during the year — — — —
on vested options lapsed in the year — — 2477 2477
on vested warrants lapsed during the year — — 111833 111833
movement in the year 13706139 16107325 645743 30459207
at 31 december 2010 54189445 22064283 3831634 80085362
on shares issued in the year 2974121 — — 2974121
 – less costs of share issue 427316 — — 427316
on options in issue during the year — — 120474 120474
on options exercised during the year — — — —
on vested options lapsed in the year — — 1795928 1795928
on issued warrants during the year — — 795 795
movement in the year 2546805 — 1674659 872146
at 31 december 2011 56736250 22064283 2156975 80957508
due to the size of the retained loss the company has no distributable reserves
the share premium account reflects the premium to nominal value paid on issuing shares less costs relating to the issue 
the merger reserve was created on the issuance of shares relating to the acquisition of silence therapeutics ag 
the share‑based premium reserve reflects the cost to issue share‑based compensation primarily employee stock options silence therapeutics plc annual report and accounts 201 1 financial statements · 49
21 equity‑settled share‑based payments
the company has two share option schemes open to all employees of the group options are exercisable at a price equal to the market 
price of the company’s shares on the date of grant 
in the inland revenue approved scheme the vesting period is three years and should the options remain unexercised they lapse after 
ten years from the date of grant the options also lapse after six months following the employee leaving the group 
under the unapproved share option scheme the options vest at dates set by the board at the time the option is granted the options 
lapse after six months following the employee leaving the group
as part of the fee structure in respect of the acquisition of silence therapeutics ag and the subsequent fundraising in mid‑2005 the group 
issued warrants to its advisers which could be exercised at any time within five years from the date of issue most of those warrants 
have been converted into shares see note 19 on page 46 the remaining warrants expired unexercised on 24 july 2010
details of the share options and warrants outstanding at the year end are as follows
2011 2010
number
weighted 
average 
exercise price number 
weighted 
average
exercise price
options
outstanding at the beginning of the year 24674843 2840p 20585547 2982p
granted during the year 29725000 187p 4089296 2123p
lapsed during the year 12637396 2487p — —
exercised during the year — — — —
outstanding at the year end 41762447 1057p 24674843 2840p
exercisable at the year end 11853069 3118p 21530619 2947p
warrants
outstanding at the beginning of the year — — 925926 2700p
granted during the year 462963 2700p — —
lapsed during the year — — 925926 2700p
exercised during the year — — — —
outstanding at the year end 462963 2700p — —
exercisable at the year end 462963 2700p — —
the options outstanding at the year end have a weighted average remaining contractual life of 87 years 2010 64 years the exercise 
price of the options outstanding at the year end range from 180p to 12700p per share full details are given in note 18 above
the group granted 29725000 options during the year the fair values of options granted were calculated using a binomial model 
and the inputs into the model were as follows
2011 2010
weighted average share price 192p 1875p
weighted average exercise price 187p 21225p
expected volatility 100 70
risk‑free rate 149–153 414
expected dividend yield — —
expected volatility was determined using as a base the share price movements recorded over the previous four years and taking into 
account any specific factors impacting during that period
the expected life used in the model has been adjusted based on management’s best estimate for the effects of non‑transferability 
exercise restrictions and behavioural considerations 
the group recognised total charges of £121269 2010 £659018 related to equity‑settled share‑based payment transactions during 
the year
22 capital commitments
there were no capital commitments at 31 december 2011 or 31 december 2010 50 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
23 contingent liabilities
there were no contingent liabilities at 31 december 2011 or at 31 december 2010
24 commitments under operating leases
the group and company have one operating lease in respect of the office in london uk which was entered into in august 2011 
at 31 december 2010 the group had one operating lease in respect of the office in redwood city california and which ended in 
september 2011 the company did not have any other operating lease commitments than redwood city california at 31 december 2010 
group non‑cancellable operating lease rentals are payable as follows
group
2011
company
2011
group
2010
company
2010
less than one year 6861 6861 29644 —
between one and five years — — — —
more than five years — — — —
25 financial instruments and risk management
the group’s financial instruments comprise primarily cash and various items such as trade debtors and trade creditors that arise directly 
from its operations the main purpose of these financial instruments is to provide working capital for the group’s operations the group 
does not utilise complex financial instruments or hedging mechanisms in respect of its non‑sterling operations the group assesses 
counterparty risk on a regular basis board approval is required for adoption of any new financial instrument or counterparty the primary 
focus of the treasury function is preservation of capital 
financial assets by category
the categories of financial assets as defined by ias 39 “financial instruments recognition and measurement” included in the balance 
sheet and the headings in which they are included are as follows
group
2011
£
company
2011
£
group
2010
£
company
2010
£
current assets
trade and other receivables 64615 33280 694684 18102
cash and cash equivalents 3687860 3322705 3566877 2283300
categorised as loans and receivables 3752475 3355985 4261561 2301402
all amounts are short‑term and none are past due at the reporting date
financial liabilities by category
the categories of financial liabilities as defined by ias 39 included in the balance sheet and the headings in which they are included 
are as follows
group
2011
£
company
2011
£
group
2010
£
company
2010
£
current liabilities
trade and other payables 1259984 181885 1686516 249846
categorised as financial liabilities measured at amortised cost 1259984 181885 1686516 249846
all amounts are short‑term and payable in zero to three months 
credit risk
the maximum exposure to credit risk at the reporting date by class of financial asset was
group
2011
£
company
2011
£
group
2010
£
company
2010
£
loans and receivables 174346 79492 782596 46024
capital management
the group considers its capital to be equal to the sum of its total equity the group monitors its capital using a number of kpis including 
cash flow projections working capital ratios the cost to achieve preclinical and clinical milestones and potential revenue from existing 
partnerships and ongoing licensing activities the group’s objective when managing its capital is to ensure it obtains sufficient funding 
for continuing as a going concern the group funds its capital requirements through the issue of new shares to investors milestone 
and research support payments received from existing licensing partners and potential fees from new licensees  silence therapeutics plc annual report and accounts 201 1 financial statements · 51
25 financial instruments and risk management continued
interest rate risk
the nature of the group’s activities and the basis of funding are such that the group has significant liquid resources the group uses 
these resources to meet the cost of future research and development activities consequently it seeks to minimise risk in the holding of 
its bank deposits while maintaining a reasonable rate of interest the group is not financially dependent on the income earned on these 
resources and therefore the risk of interest rate fluctuations is not significant to the business nonetheless the directors take steps to 
secure rates of interest which generate a return for the group by depositing sums which are not required to meet the immediate needs 
of the group in interest‑bearing deposits other balances are held in interest‑bearing instant access accounts all deposits are placed 
with main clearing banks to restrict both credit risk and liquidity risk the deposits are placed for the short term between one and three 
months to provide flexibility and access to the funds and to avoid locking into potentially unattractive interest rates 
liquidity risk
the group’s liquid resources are invested having regard to the timing of payments to be made in the ordinary course of the group’s 
activities all financial liabilities are payable in the short term between zero and three months and the group maintains adequate bank 
balances in either instant access or short‑term deposits to meet those liabilities as they fall due
currency risk
the group operates in a global market with income possibly arising in a number of different currencies principally in sterling us dollars 
or euros the majority of the operating costs are incurred in euros with the remainder predominantly in sterling the group does not 
hedge potential future income since the existence quantum and timing of such income cannot be accurately predicted
financial assets and liabilities denominated in euros and translated into sterling at the closing rate were 
group
2011
£
company
2011
£
group
2010
£
company
2010
£
financial assets 403370 — 1486612 —
financial liabilities 308362 — 674104 —
net financial assets 95008 — 812508 —
financial assets and liabilities denominated in us dollars and translated into sterling at the closing rate were 
group
2011
£
company
2011
£
group
2010
£
company
2010
£
financial assets 297925 — 555502 —
financial liabilities 769246 — 754567 —
net financial liabilities 471321 — 199065 —
the following table illustrates the sensitivity of the net result for the year and the reported financial assets of the group in regards 
to the exchange rate for sterlingeuro
during 2011 the sterlingeuro exchange rate remained broadly stable during the year sterling appreciated by 3 versus the euro 
the table shows the impact of a further strengthening or fall of sterling against the euro by 20
2011
as reported
£
if sterling
 rose 20
£
if sterling
fell 20
£
group result for the year 5736563 5095827 6697668
euro denominated net financial assets 95008 79174 118761
total equity at 31 december 2011 32177888 32017499 32418471
2010
as reported
£
if sterling
 rose 20
£
if sterling
fell 20
£
group result for the year 8795274 8286336 9558680
euro denominated net financial assets 812508 677090 1015635
total equity at 31 december 2010 32269675 31218054 33847099 52 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
notes to the financial statements continued
year ended 31 december 2011
25 financial instruments and risk management continued
currency risk continued
the table shows the impact of a further strengthening or fall of sterling against the us dollar by 20
2011
as reported
£
if sterling
 rose 20
£
if sterling
fell 20
£
group result for the year 5736563 5512150 6073183
us dollar denominated net financial assets 471321 392768 589152
total equity at 31 december 2011 32177888 28665876 37445907
2010
as reported
£
if sterling
 rose 20
£
if sterling
fell 20
£
group result for the year 8795274 8217046 9662616
us dollar denominated net financial assets 199065 165887 248831
total equity at 31 december 2010 32269675 28245300 38306230
26 related party transactions
during the year the company charged a management fee to its subsidiary companies silence therapeutics ag and intradigm corporation 
amounting to £182843 2010 £100581 and £63485 2010 £29237 respectively during the year intradigm corporation charged the 
company a management fee of £126131 2010 £187612
related party transactions were made on terms equivalent to those that prevail in arm’s length transactions full details of capital 
contributions and loans made during the year to the company’s subsidiaries can be found in note 14 
27 subsequent events
there were no subsequent events to report company information 
and advisers
secretary
max herrmann 
registered office
22 melton street 
london nw1 2bw
registered number 
2992058
nominated advisers
singer capital markets ltd
1 hanover street
london w15 1yz
registrars
capita irg plc
northern house
woodsome park
fenay bridge
huddersfield hd8 0la
auditors
kpmg audit plc
15 canada square 
london e14 5gl silence therapeutics plc annual report and accounts 2011
silence therapeutics plc
the royal institution of great britain
21 albemarle street
london w1s 4bs
tel 44 0 20 7491 6520
fax 44 0 20 7491 6521
email mailsilencetherapeuticscom
wwwsilencetherapeuticscom


Summary:
 06 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
overview
since joining silence therapeutics in september 2011 
i have been excited by the company and the opportunities 
that lie ahead as a consequence i was pleased to take over 
as chief executive officer in february 2012 as i believe 
we have a unique proprietary position in rnai therapeutics 
and their delivery over the next few years i intend to increase 
the commercial focus of the company harness the rnai 
therapeutics opportunity and as a result create substantial 
shareholder value
2011 has been an exciting year for silence therapeutics 
with progress across all areas of the business we started 
this year looking forward to clinical data to validate both 
the therapeutic benefit to be obtained by rna interference 
rnai or sirna as well as our proprietary delivery 
technologies i am pleased to report that our company 
has delivered on this expectation in both our proprietary 
and partnered programmes 
we have also worked hard on building the financial future 
of the business improving its efficiency and strengthening 
its commercial activities all of which is discussed below 
silence therapeutics is proud of its rnai therapeutic 
platform comprising proprietary delivery technologies 
potent sirna sequences and innovative rnai structural 
features we believe that our progress in 2011 shows the 
synergistic value of these propositions 
encouraging clinical data
silence therapeutics is prominent in an exciting new sector 
in the drug development arena the translation of rna blocking 
rnai technology into therapies since we and others active 
in this area believe that the technology has potential in a broad 
range of clinical indications – including oncology vascular 
metabolic and ophthalmic diseases – it brings the potential 
for better patient outcomes in these major therapeutic areas 
one of the first steps in demonstrating this potential is the 
generation of data from clinical studies conducted with 
rnai therapeutics
in june 2011 silence presented encouraging interim data 
from its ongoing phase i trial of proprietary product atu027 
in patients with solid tumours at the prestigious annual meeting 
of the american society of clinical oncology asco 
we believe that these important findings serve as valuable 
validation for silence’s rnai technology platform as well 
as its atuplex™ delivery technology this should stand the 
company with its increased business development focus 
in good stead as we work on partnering our programmes 
and exploiting our valuable rnai delivery intellectual 
property estate 
to summarise silence therapeutics made progress in several 
key areas in 2011 which we discuss in more detail below 
these include
 i clinical trial progress for both our proprietary and 
partnered programmes
 i three new delivery deals with further progress 
in established programmes
 i sharpening of our business development focus 
with important new top‑level hires
 i refinancing and restructuring of the organisation and
 i further development and recognition of silence’s 
intellectual property portfolio particularly in the area 
of rnai delivery
operational
clinical trial progress for both our proprietary 
and partnered programmes
clinical trial data is key to establishing the potential of rnai 
therapeutics and we are pleased that it generated significant 
excitement this year both for silence and its partners 
proprietary programmes
atu027 silence therapeutics’ lead programme for cancer
in 2011 we were able to report impressive interim results 
from the phase i ascending dose clinical trial of our lead 
programme cancer treatment atu027 for solid tumours 
atu027 incorporates our atuplex delivery system with 
aturnai our proprietary rnai chemistry and specifically 
targets pkn3 a protein implicated in cancer growth 
and metastases
these results were presented at asco and showed stabilisation 
of the disease in 38 of the cases 9 of 24 patients as well 
tony sedgwick chief executive officer
chief executive’s review
“ wehaveworkedhardonbuildingthefinancialfutureofthebusiness
improvingitsefficiencyandstrengtheningitscommercialactivities” silence therapeutics plc annual report and accounts 201 1 business review · 07
as other indications of potential efficacy importantly on 
the safety side the trial data obtained so far have indicated 
that atuplex is safe in humans at dose levels above those 
that have shown effectiveness in preclinical studies among 
the patients who achieved stable disease one individual with 
neuroendocrine cancer achieved disease stabilisation for 
nine months with a second neuroendocrine cancer patient 
showing partial regression of pulmonary metastases 
an additional patient with breast cancer experienced 
some regression in liver metastases 
32 patients have been treated so far and enrolment of all 
33–36 patients is expected to be completed in the first half 
of 2012 with results announced in the middle of the year 
the company believes that the encouraging data 
received to date represents an important step along the 
path towards realising value for shareholders assuming 
successful completion of the phase i study we expect to initiate 
a phase ibiia clinical study of atu027 in the second half of 
2012 the company will also continue licensing discussions 
regarding atu027 with potential pharmaceutical partners 
atu111 our most advanced product outside oncology
atu111 for the treatment of acute lung injury is our most 
advanced drug development candidate outside oncology 
it combines our dacc drug delivery system with aturnai 
and its target is undisclosed we have recently completed 
proof of concept studies in a preclinical model of acute lung 
injury demonstrating very impressive results using atu111 
further studies are ongoing in a variety of other preclinical 
models of the disease 
earlier preclinical work using atu111 has shown sustained 
gene knockdown of up to three weeks in the lung endothelium 
suggesting the drug could be used with a single dose 
atu134
following the encouraging data generated from the ongoing 
phase i trial of atu027 and additional data from preclinical 
models of atu134 silence has concluded that the potential 
clinical profiles of these two products are too similar to 
warrant further development of both programmes we 
therefore decided in november to divert the resources for 
atu134 to other areas specifically potential targets in the liver 
that could be inhibited by using silence’s novel liver‑focused 
dbtc delivery system 
partnered programmes
silence therapeutics has two licence agreements with partner 
quark pharmaceuticals for products pf‑04523655 and 
qpi‑1002 both of which are in development in two different 
therapeutic indications quark has licensed these to pfizer 
and novartis respectively the positive data received from 
the programmes in 2011 further highlights both the potential 
of rnai therapeutics and of silence’s aturnai technology 
which is incorporated into these products
q u a r k  p fi z e rp r o g r a m m e s
in march 2011 quark announced the completion of the degas 
study a phase ii clinical trial of pf‑04523655 for the treatment 
of the ophthalmic indication of diabetic macular oedema 
the product which incorporates silence’s aturnai technology 
was shown to be more effective than laser therapy quark 
has now initiated a phase iib study comparing pf‑04523655 
to lucentis rochenovartis the new standard of care in the 
treatment of diabetic macular oedema 
in addition pf‑04523655 recently completed a phase ii trial 
in the second ophthalmic indication of age related macular 
degeneration the trial demonstrated a dose‑dependent increase 
in benefit of pf‑04523655 quark is now awaiting results from 
the phase iib trial in diabetic macular oedema before deciding 
on plans for the drug in age‑related macular degeneration
quarknovartis programmes
in august 2010 quark signed an option and licence agreement 
with novartis for qpi‑1002 as mentioned previously in september 
of that year quark initiated a phase ii study in prevention 
of delayed graft function in patients undergoing kidney 
transplantation recruitment into this trial has progressed 
well and we expect the trial to be completed in the middle 
of 2012 a phase i study has been successfully completed 
in the second indication of acute kidney injury quark plans 
to initiate a phase ii trial depending on the results of the 
ongoing trial in the prevention of delayed graft function 
summary
 i silence therapeutics is a leader in an exciting new drug 
development arena known as rnai
 i silence made significant progress in 201 1 with its internal pipeline 
in particular interim phase i data of lead programme atu027 was 
presented in june at the prestigious annual meeting of the 
american society of clinical oncology asco 
 i silence’s partnered programmes made significant advances during 
2011 with pf04523655 quarkpfizer successfully completing a 
phase ii trial in diabetic macular oedema and qpi1002 progressing 
well in a phase ii trial in prevention of delayed graft function
 i the value of this portfolio of delivery technologies was underlined 
in 201 1 with the signature of three agreements with new partners 
interna technologies bv mirna therapeutics inc and a top ten 
pharmaceutical company
 i silence therapeutics has two licence agreements with 
partner quark pharmaceuticals for products pf 04523655 
and qpi 1002 both of which are in development in two 
different therapeutic indications
 i efficient and safe delivery of rnai therapeutics is key to the 
success of the field and silence now has three such delivery 
systems atuplex dacc and dbtc 08 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
progress in research collaborations
silence is pleased to have been working with astrazeneca 
in the area of rnai since 2007  in the form of two collaborations 
both of which were extended in 2010 astrazeneca has now 
completed the research phase of the first of these collaborations 
a research and development collaboration focused on five 
respiratory and oncology targets and nominated three of 
the five targets as “accepted programmes” 
the second collaboration for the development of novel 
approaches for the delivery of sirna molecules was 
entered into in march 2008 the research phase of this 
collaboration has also been completed and astrazeneca 
retains the right to use the dacc delivery system developed 
for their “accepted programmes”
valuable portfolio of delivery technologies
efficient and safe delivery of rnai therapeutics is key to the 
success of the field and silence therapeutics’ programmes 
as well as those of other companies active in this area 
the company possesses three proprietary sirna delivery 
technology platforms atuplex dacc lung and dbtc liver 
two of which are already being used in the programmes of 
partners this comprehensive delivery platform allows our rnai 
therapeutics to reach many different organs with the liver and 
lungs increasingly becoming targets of interest in the rnai field 
and the pharmaceutical industry generally 
because of the importance of appropriate delivery in 
this therapeutic area we believe our delivery platform will 
deliver significant value to the company via non‑exclusive 
partnership deals 
 i atuplex enables the delivery of sirna molecules to targeted 
diseased tissues and cells in the vascular endothelium blood 
vessels while increasing their bioavailability and intracellular 
uptake it incorporates silence’s proprietary lipid atufect and 
is used to embed sirnas into a multiple lipid bi‑layer 
structure it is incorporated in atu027 
 i the dacc novel lipid delivery system enables functional 
highly specific and efficient delivery of sirna molecules 
selectively to the lung endothelium with a long duration of 
action over three weeks like atuplex it also incorporates 
silence’s proprietary lipid atufect and is used to embed 
sirnas into a multiple lipid bi‑layer structure the dacc 
delivery system is incorporated in atu111 silence’s preclinical 
development candidate for the treatment of acute lung injury
 i the dbtc delivery system is lipid‑based and targets the 
liver studies have shown it to be well tolerated and have 
a significant duration of action it therefore has therapeutic 
potential in areas such as heptatocellular carcinoma liver 
fibrosis and acute liver failure 
chief executive’s review continued
“ the value of our portfolio of delivery technologies was underlined 
in 2011 with the signature of three agreements with new partners”
goal review
last year we set ourselves some goals for completion 
at the end of 2011
1  complete phase i clinical 
trial of atu027
completion is now expected in the middle of 2012
2  present interim phase i 
data on atu027
data was presented at the american society 
of clinical oncology asco
3   ad v a n c e p r e c li n i c a l 
programmes for atu134 
and atu111
atu111 continues to progress through preclinical 
development however in november 2011 the 
decision was taken to refocus resources away 
from atu134
4   c o m p l et e n e w 
corporate alliances
during 2011 silence signed three new collaborations 
relating to its rnai delivery technologies
our goals for 2012
1 complete phase i clinical trial of atu027
2 announce results of atu027
3 advance atu111 and establish new preclinical programmes
4 complete new corporate alliance silence therapeutics plc annual report and accounts 201 1 business review · 09
three new delivery deals
the value of this portfolio of delivery technologies was 
underlined in 2011 with the signature of three agreements 
with new partners interna technologies bv mirna 
therapeutics inc and a top ten pharmaceutical company 
interestingly two of these three agreements were for a 
different form of rna therapeutic to the sirna approach 
being used by silence therapeutics ie microrna this 
emphasises the value of our delivery platform 
in september we established an agreement with 
interna technologies bv which is developing microrna 
mirna‑based therapeutics for cancer microrna 
intervention is an exciting new therapeutic area for which 
the silence technology platform is well suited and the 
deal was our first in this area we are looking forward to 
the results from this collaboration which we believe will 
demonstrate the potential of atuplex for the delivery 
of rna‑based therapeutics outside of the sirna arena 
under the agreement we will combine silence’s proprietary 
atuplex delivery system with interna’s novel micrornas 
to develop multiple novel candidate drugs the two companies 
will then undertake in vitro and in vivo studies of the candidate 
drugs and select lead candidates for further evaluation 
silence is eligible to receive up‑front fees as well as staged 
research payments if the collaboration progresses 
the potential of silence therapeutics’ delivery technologies 
in this new area was further underlined in october 2011 with our 
second mirna deal the collaboration with mirna therapeutics  
is to investigate the potential of both atuplex and our dbtc 
delivery system with our partner’s novel micrornas for the 
treatment of cancer we are pleased that our first deal on 
dbtc is in this exciting new therapeutic area silence 
therapeutics will formulate selected mirna sequences into 
atuplex and dbtc in order to generate candidate drugs 
which will then undergo in vitro and in vivo testing at mirna 
in order to select those to take forward for further evaluation 
in october 2011 we also signed an sirna delivery 
collaboration for dacc with a top ten pharmaceutical 
company – our first deal covering this technology for delivery 
to the lung under the terms of the agreement our partner 
will provide us with specific sirnas which we will formulate 
into the dacc delivery system silence and its partner will 
undertake in vitro and in vivo studies of the dacc‑formulated 
sirnas developed under the agreement and select lead 
candidates for further evaluation 
silence’s impressive pipeline of products not only validates the strength 
of the company’s technology but also the depth of knowledge that has 
guided the development path
products partners target  
tissueorgan
delivery  
method
market size discovery pre‑clinical phase i phase ii phase iib
pf‑4523655
diabetic macular  
edema
pfizerquark rtp801 – local delivery  
to the eye
naked sirna 1bn  
potential
pf‑4523655
agerelated macular 
degeneration
pfizerquark rtp801 – local delivery  
to the eye
naked sirna 31bn  
2010
qpi‑1002
prevention of delayed 
graft function
novartisquark p53 – systemic delivery  
to the kidney
naked sirna 44bn  
2010
qpi‑1002
acute kidney injury 
novartisquark p53 – systemic delivery  
to the kidney
naked sirna 1bn  
potential
aut027
solid tumours 
silence pkn3 – systemic delivery  
to tumour endothelium
atuplex 82bn  
angiogenesis  
mkt 2010
atu111
acute lung injury
silence systemic delivery  
to lung endothelium
dacc 1bn  
potential
liver diseases
dbtc programs
silence systemic delivery  
to liver hepatocytes  
and endothelium
dbtc undisclosed
lung diseases
dacc system 
silence systemic delivery  
to lung endothelium
dacc undisclosed 10 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
ongoing delivery collaborations progress
in addition to these exciting new deals we have an ongoing 
sirna delivery collaboration with dainippon sumitomo 
signed in 2008 under this collaboration we are jointly 
leveraging silence’s proprietary sirna molecules and 
delivery technologies to demonstrate delivery of rnai 
therapeutics to specific disease targets this agreement 
which originally included two drug targets was expanded 
in 2010 to include two more 
securing our financial position
silence therapeutics ended 2010 with cash reserves of 
£357m and we indicated in the first quarter of 2011 that 
we would be seeking additional funding to drive continued 
development of the company accordingly in may 2011 
silence successfully raised £551m net of expenses through 
a placing and open offer 
given the substantial financial and economic volatility 
experienced globally over the last few years particularly 
in the biotechnology sector we were extremely pleased with 
this result which gave us a substantially improved financial 
footing and extended the cash runway to the end of the 
third quarter of 2012 from existing cash resources alone 
the fundraising was supported by both existing and new 
shareholders whom we thank for their support and welcome 
to silence therapeutics 
part of the proceeds are to be used to among other things 
complete the ongoing phase i trial and initiate a phase ib 
trial of atu027 and advance preclinical development of the 
atu111 programme for lung disease as shareholders can 
see we have made progress in these areas and expect to 
continue to do so
a streamlined business focused 
on business development
increased financial efficiency
as 2011 progressed it became clear to silence therapeutics 
that in order to create a more streamlined and efficient business 
some streamlining and consolidation of operating sites was 
needed following the 2010 acquisition of intradigm inc 
managing and working across our three sites in the uk 
germany and the us had generated considerable operational 
difficulties as well as increased costs 
in april 2011 we announced plans to close our redwood 
city office in california this was completed in august 
as a consequence our us‑based chief executive officer 
dr phil haworth stepped down i joined the business in 
september initially as chief business officer but was 
delighted to be able to accept the appointment as chief 
executive officer in february 2012 following the departure 
of thomas christély who took on the role of chief executive 
officer briefly after the departure of dr haworth
with the us‑based business development and legal functions 
absorbed elsewhere in the group its operations are now 
based in berlin where our research and development 
facilities have always been located in addition there 
is a small management presence in london 
in addition to the closure of the us facility we were able 
to further streamline the business by reducing headcount 
in berlin from 32 to 27 via the loss of some non‑critical 
roles and by reducing the size of our board the latter had 
become too large following the acquisition of intradigm 
corporation and as a consequence dr james topper 
and dr david u’prichard resigned from the board of directors 
effective 29 july 2011 and 31 december 2011 respectively 
we thank both dr topper and dr u’prichard for their valuable 
contribution to silence therapeutics 
these measures helped us to increase our cash runway and 
combined with our fundraising mean that we have sufficient 
funding to last us until q3 2012 
significantly strengthened business 
development focus
with encouraging data so far from the phase i trial 
of atu027 and the level of interest in silence therapeutics’ 
rnai delivery technologies in 2011 it was clearly time 
to invest more significantly in our business development 
activities an important part of this will be the partnering 
with and generation of value from these assets in addition 
with the availability of finance significantly reduced in the 
current economic crisis the global biotechnology sector 
has increasingly accessed non‑dilutive financing from 
sources such as public sector organisations for example 
research councils and leading charities we consider 
this to be a major objective in our enhanced business 
development activity 
strong business development team
our business development activity was further enhanced 
in november 2011 with the appointment of dr georg buchner 
as vice president of business development georg was 
formerly vice‑president of corporate and business development 
at novacta biosystems ltd novacta prior to joining novacta 
georg was business development director at haptogen ltd 
where he was instrumental in the sale of the business to wyeth 
now part of pfizer in 2007 he has a phd in molecular genetics 
from king’s college london and an mba from the university 
of cambridge’s judge institute of management and will be 
working with myself to continue to broaden our collaborations 
with global pharmaceutical and biotechnology companies
chief executive’s review continued
“ in  2011  we  achieved  signifi cant  success  in  obtaining  new  issued  patents 
further strengthening protection of our innovative technologies” silence therapeutics plc annual report and accounts 201 1 business review · 11
strength through intellectual property
our broad and diverse intellectual property portfolio 
continues to provide us with a competitive advantage 
and a strong proprietary position in the rnai therapeutics 
space we believe that we have been successful in aggressively 
building one of the world’s most comprehensive rnai patent 
estates and expect that this asset will continue to offer 
significant support for our ongoing partnering activities 
our patent estate covers the areas which we believe to be 
pivotal to the successful development of rnai therapeutics 
from the structure of the molecules themselves to how they 
are delivered in addition we have achieved significant 
successes in establishing key levels of patent protection 
for our technologies in europe the us and japan offering 
opportunities in these important healthcare markets silence 
remains committed to the expansion and strengthening of 
its intellectual property portfolio in target markets around the 
globe in 2011 we made progress in both the us and japan 
covering rnai structures and delivery as well as receiving 
further confirmation of the strength of the zamore design 
rules patents as discussed below 
patent issuance and success versus challenges
in the us a new patent that broadens silence therapeutics’ 
existing protection of optimised rnai molecules including 
our proprietary aturnai platform was issued also in that 
territory we received a notice of allowance of a new patent 
that provides protection for a core component of our 
proprietary atuplex delivery platform 
protection in japan was enhanced by issuance of a patent 
covering novel aturnai molecules which will support 
our efforts to establish partnerships with leaders in the 
pharmaceutical industry there in addition we received 
news of issuance of a japanese patent covering methods 
for screening a therapeutic agent for the treatment andor 
prevention of any disease that involves elevated activity 
within the pi3‑kinase pathway this new intellectual property 
includes coverage for the use of the gene target protein 
kinase n beta ‘pkn3’ for screening of therapeutic agents 
and is important to us as pkn3 is the target of our leading 
therapeutic programme atu027 
our patents in this area were further supported in december 2011 
with a positive outcome from an oral hearing at the european 
patent office epo over the opposition to silence’s granted 
european patent ep 1 536 827 “further use of protein kinase 
n beta” the opposition division of the epo decided to uphold 
the patent in amended form now restricted to metastatic cancers 
this is the focus of silence’s ongoing atu027 phase i study 
and we are pleased that the product continues to be protected 
by this intellectual property and other patents for example 
those around atuplex and the aturnai sequence used 
in the product 
looking at atu027
silence’s lead internal rnai therapeutic candidate 
atu027 is currently in a phase i clinical trial atu027 has 
demonstrated anticancer activity against a broad range 
of tumour types including gastrointestinal nonsmall 
cell lung prostate melanoma breast and others
topline data presented at asco in june 2011 included 
results for 24 patients who received the study’s first eight 
doses of atu027
 i six of these patients experienced stable disease after 
three months
 i one patient with neuroendocrine cancer had disease 
stabilization for nine months
 i a second neuroendocrince cancer patient experienced 
partial regression of pulmonary metastases
 i a patient with breast cancer demonstrated regression 
of liver metastases
“ this positive data is very encouraging 
and we believe the disease stabilization 
and antitumor activity in particular 
are suggestive of a potential therapeutic 
be n e fi t  f o r  e x tr e m e l y  ill  p a ti e n ts  w h o 
have no other treatment options” 12 · silence therapeutics plc annual report and accounts 201 1 wwwsilencetherapeuticscom
operational continued
patent issuance and success versus challenges 
continued
silence has exclusive licences covering three patent families 
from the university of massachusetts medical school 
collectively known as the “zamore design rules” in 2011 
following an anonymous request four of the us patents 
covering the zamore design rules successfully completed 
re‑examination by the us patent and trademark office 
uspto and in december 2011 we were able to report 
that the uspto had issued “notices of intent to issue 
re‑examination certificates” in europe the patent is 
currently being opposed by alnylam and other parties
investor relations ir strategy 
silence therapeutics maintains active communications 
and an investor relations strategy to provide transparency 
and maximise dialogue with its stakeholders
as part of its 2011 ir strategy silence has held investor 
meetings across europe and attends investor conferences 
internationally throughout the year full details of which 
can be found on the company’s website 
httpsilence‑therapeuticscom 
in line with the london stock exchange’s aim requirements 
silence discloses its investor news on a frequent basis via 
its regulatory information service provider and the company 
holds a number of conference calls and meetings throughout 
the year in order to reach investors effectively in addition 
the company’s website serves as an effective tool for 
investor communications 
silence also participates in the evolving social media scene 
and communicated digitally online with frequency through 
linkedin facebookyoutube and recently twitter in february 
2012 silence launched its new website designed with a range 
of interactive features and online social media tools to reflect 
the new direction and more commercial focus of the company 
these included twitter feeds company news flashes and 
regular industry updates from its real‑time rnai hub 
summary and outlook
during 2011 silence therapeutics has built a significantly 
stronger business more able to deal with the rigours of 
today’s financial climate and better placed to exploit our 
wealth of assets by restructuring the business strengthening 
the management team and raising a significant amount of 
financing in challenging economic conditions we believe we 
have more than justified the decision made at the beginning 
of the year to remain an independent business 
exciting year ahead
2012 will be an important and exciting year for silence 
therapeutics with a new and commercially focused 
management team the company is set to achieve 
shareholder value uplift importantly there will be clinical 
data from us both for atu027 and our partnered products 
as well as other companies in the sector 2012 clinical news 
flow expected from us and our partners includes the anticipated 
start of phase ibiia clinical trials with atu027 this will be 
an important milestone for silence therapeutics 
as well as continuing to develop our pipeline key priorities 
for silence this year are to secure the company’s financial 
future and to continue to generate value through partnering 
our fundraising and moves to reduce cash burn this year 
have extended our cash runway to the end of the third quarter 
of 2012 not taking into account potential milestones from 
our collaboration partners 
with our enhanced business development function we will 
be looking at building value and generating income through 
our partnering activities one of our priorities in this area is 
the signature of out‑licensing or co‑development agreements 
for atu027 or other internal candidates such as atu111 
assuming they continue to generate encouraging data 
silence also believes that the quality of its rnai therapeutic 
platform – including aturnai and our portfolio of delivery 
technologies – will continue to be recognised by partners in 
licensing deals and research collaborations we are proud of 
our list of partners – which includes four of the top ten global 
pharmaceutical companies – and expect to add to it in 2012 
silence plans to attend scientific and medical conferences 
throughout the year in order to undertake a structured 
outreach to our key audiences we are pleased to confirm 
that during 2012 dr klaus giese silence’s chief scientific 
officer plans to present at a number of world‑leading 
biopharmaceutical events
another area of focus for the business development team 
will be looking at accessing non‑dilutive forms of financing 
such as grants from the large research charities in recent 
years this type of funding has grown in importance to the 
global biopharmaceutical sector partly driven by financial 
and economic conditions silence therapeutics considers 
it an important option for the company to develop our 
pipeline of therapeutics and build shareholder value 
providing as it does the foundation of our business 
we will continue to prosecute defend and grow our 
intellectual property portfolio areas of focus for additional 
patent protection include all essential components of rnai 
therapeutic development including multiple proprietary 
sirna delivery technologies potent sirna sequences 
and key sirna sequence and chemical modifications 
as well as specific high‑value disease targets
2012 looks to be an exciting year for us in concluding my 
comments it is important for me to note that the achievements 
we made in 2011 were only possible through the hard work 
and dedication of our staff and the support of our shareholders 
my thanks are due to all of you as we work together to bring 
much‑needed rnai therapeutics to patients 
tony sedgwick phd
chief executive officer
27 march 2012
chief executive’s review continued