Corporate Overview

December 2011

Developing and Commercializing

Cardiovascular Disease Diagnostics

OTCBB: DDXS.OB

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Forward Looking Statements

This presentation contains forward-looking statements within the meaning of the Private Securities Litigation

Reform Act of 1995. Such statements include, but are not limited to, statements about the company’s plans,

objectives, expectations and intentions with respect to future operations and products and other statements that

are not historical in nature, particularly those that use terminology such as “will,” “potential”, “could,” “can,”

“believe,” “intends,” “continue,” “plans,” “expects,” “projects,” “estimates” or comparable terminology.

Forward-looking statements are based on current expectations and assumptions, and entail various known and

unknown risks and uncertainties that could cause actual results to differ materially from those expressed in such

forward-looking statements.

Important factors known to diaDexus that could cause actual results to differ materially from those expressed

in such forward-looking statements include diaDexus’ ability reintroduce our PLAC TIA product, shipments of

which were suspended in May 2010; diaDexus’ ability to demonstrate that treatment of individuals based on their

Lp-PLA2 levels improves clinical outcomes in prospective clinical studies; the rate of adoption of the PLAC Test by

doctors and laboratories; the insurance payer community’s acceptance of and reimbursement for the PLAC Test;

diaDexus’ reliance on sole source third party manufacturers to manufacture and supply our main reagent and the

PLAC Test; our ability to retain key employees and to attract, retain and motivate other qualified personnel;

diaDexus’ limited revenue and cash resources; and diaDexus’ significant corporate expenses, including expenses

associated with being a public company.

Additional factors that could cause diaDexus’ results to differ materially from those described in the forward-

looking statements can be found in diaDexus’ most recent annual report on Form 10-K, most recent quarterly

report on Form 10-Q and other reports filed with the Securities and Exchange Commission, which are available at

the SEC’s web site at www.sec.gov. The information set forth herein speaks only as of the date hereof, and

diaDexus disclaims any intention and does not assume any obligation to update or revise any forward looking

statement, whether as a result of new information, future events or otherwise.

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The PLAC Test

The PLAC Test for Lp-PLA2

The only blood test that helps identify hidden risk for heart attack and stroke.

Early detection and more aggressive treatment can help prevent these cardiovascular events.

• The PLAC Test measures Lp-PLA2 (lipoprotein-associated phospholipase A2) a vascular-specific inflammatory enzyme implicated in the formation of rupture-prone plaque.

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Highlights

PLAC® Test for Lp-PLA2:

– FDA approved

– A simple blood test

Projecting record sales in 2011 (guidance $15 - 16M)

Revenue growth potential

– Near-term: PLAC® (ELISA-based “Mass” assay )

• In association with CVD labs, increase market penetration

• Increased reimbursement

• Market expansion program

– Mid-term: New “Activity” assay

• EU launch H1 2012

• New features open new markets

• Foundation for testing in all clinical laboratories

– Longer-term: Personalized medicine

Cash sufficient at least through YE 2012

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Cardiovascular Dx Market / Opportunity

United States

Annual

Statistics1

1.3MM coronary attacks

425K deaths

#1 Killer in US

795K strokes

137K deaths

#4 Killer in US

#1 cause of long-term disability

Ischemic Stroke Coronary

Heart Disease

1. Heart Disease and Stroke Statistics – 2010 Update, American Heart Association 2. National Ambulatory Medical Care Survey (NAMCS) and CMS (Codemap) - 2008 3. Ridker, PM. American Heart Journal. July 2004.

The Problem

50% of all events

strike in individuals with

“normal” lipid levels3

BEFORE the PLAC Test

No FDA-cleared test to

assess stroke risk

Current Testing Market

Lipids: 93 Million Annual Tests2

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Elevated Lp-PLA2 Associated With Unstable Plaque

Early Plaque

with Lipid Pool

Thick Cap with Small

Lipid Core

“Stable Plaque”

Thin Cap

“Rupture-Prone”

Plaque

Ruptured Plaque

Clot formation

Adapted from Kolodgie F, et al. Arterioscler Thromb Vasc Biol 2006.

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LDL-C Management Goals without PLAC test

ASSESS

TREAT

Low CV Risk

LDL-C Goal < 160 mg/dL

Very High CV Risk

Moderate

CV Risk

LDL-C Goal < 130 mg/dL

High CV Risk

LDL-C Goal < 100 mg/dL

LDL-C Goal < 70 mg/dL

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LDL-C Management Goals with PLAC test

ASSESS

TEST

TREAT

Low CV Risk

LDL-C Goal < 160 mg/dL

Very High CV Risk

Lp-PLA2 Testing

Low High

Lp-PLA2 Testing

Low High

Moderate CV Risk

LDL-C Goal < 130 mg/dL

High CV Risk

LDL-C Goal < 100 mg/dL

LDL-C Goal < 70 mg/dL

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U.S. Market Potential

ASSESS

TEST

TREAT

* Davidson MH, et al. AM J Card Suppl 2008.

Low CV Risk

LDL-C Goal < 160 mg/dL

Very High CV Risk

Lp-PLA2 Testing

Low High Lp-PLA2 Testing

Low High

Moderate CV Risk

LDL-C Goal < 130 mg/dL

High CV Risk

LDL-C Goal < 100 mg/dL

LDL-C Goal < 70 mg/dL

61 Million Lives

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Record Growth 2010 - 2011

The PLAC® Test (ELISA-based Mass assay)

High complexity, specialty laboratories driving current revenue stream

– Labs that offer comprehensive cardiovascular diagnostic lipid profile panels

Q3 ‘11 revenue of $4.4M

– Up 38% over Q3 ‘10

– Up 14% over Q2 ‘11

Q2 ‘11 revenue of $3.8M

– Up 45% over Q2 ’10

– Up 15% over Q1 ’11

Q1 ‘11 revenue of $3.3M

– Up 25% over Q1 ‘10

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Near-term “Mass” Revenue Growth:

Reimbursement

2011 base of 122 million covered live

– Expand base

Drivers for reimbursement coverage

– Outcomes data: LIPID AHA data trial shows LpPLA2 levels highly significant in predicting secondary events

– Diagnoses codes coverage

• Outreach to insurance companies in key coverage areas

• Appeals process focused on insurance company policy makers

CPT Code # 83689, NLA of $47.77

Outcomes data, scientific publications

KOL endorsement, position papers,

review articles, expanded guidelines

Obtain broad diagnostic code approval for reimbursement, move toward Standard of Care

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Near-term “Mass” Revenue Growth:

Market Expansion

Expanding market for ELISA-based PLAC® test

– Qualifying instruments for use in laboratories other than the high complexity, specialty Laboratories

– Potential access to 10x more laboratories, larger installed base

Large Clinical Chemistry Analyzers

Automated Clinical Chemistry Analyzers

The New “Activity” Assay

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Mid-term Growth: “Activity” Assay

Determines total activity levels of Lp-PLA2

– Enzyme function vs PLAC’s measurement of amount (mass) of enzyme

Clinical data confirms strong predictor for CVD

– ARIC Study, reported at Arteriosclerosis, Thrombosis and Vascular Biology (ATVB) conference, 2010

– Preparing for pre-IDE meeting with FDA

Key performance enhancements

– Ease-of-use

– Sample collection, handling and storage

– Robust predictive value

Opens up new markets

– For use on bench-top automated clinical chemistry analyzers

– EU launch H1 2012

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Mid-term Growth: “Activity” Assay

Activity assay: Opens new markets

– All clinical laboratories in EU and US

– Potential access to significant number of new customers

Automated Clinical Chemistry

Analyzers

Bench-top Clinical Chemistry

Analyzers

Personalized Medicine

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Longer-term Upside: Personalized Medicine

GSK’s Lp-PLA2 inhibitor, darapladib, in Phase III

Two parallel Phase IIIs

– First Phase III study (n=15,500 patients)

• Estimated study completion date: August 2013

– Second Phase III study (n=11,500 patients) began 12/2009

– Lp-PLA2 activity measured in both studies

Potential impact

– Ongoing Phase IIIs generally increase physician awareness of Lp-PLA2

– Darapladib clinical data: growth driver

1. www.gsk-clinicalstudyregister.com (accessed May 19, 2011)

EU Launch

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EU Launch

ISO 13485: Certified Q3 2011

– DDXS’ quality system meets highest industry standards

– Strengthens DDXS commitment to product quality and customer service

– Necessary to launch in EU

Activity assay

– Instrument qualification currently underway for 80% of EU market.

Distributers in place in 15+ countries

– Initial focus will be in limited number of countries

Presales marketing campaign - - “PREvents” currently underway

Clinical launch H1 2012

– Very modest revenue projections for 2012

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Activity Assay: Int’l Expansion

Cardiovascular disease prevalence in Europe

– CVD disease causes 4.3M deaths in Europe; 2 M deaths in EU

– CVD causes ~ half of all deaths in Europe (49%); in EU (42%)

Market expansion into 15 countries by December 2012

– Initially: Germany, France, Italy, select high potential markets

– KOL development

– Select countries require clinical data for reimbursement applications

Financials

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Revenue & Cash Used

2010

Revenue

Cash Used

In Operations

$ 11.8 MM

Full Year

2011

9 months

$ 11.5 MM

$ 5.0 MM

Cash Balance $ 20.4 MM $ 19.8 MM**

$ 7.5 MM*

* Impacted by July 28, 2010 reverse merger

** Includes $5 M Debt Financing, Q3, 2011

Net loss per share $ 0.12 $ 0.25

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Investment Highlights: Recap

Differentiated, unique selling proposition in cardiovascular Dx market

– PLAC® Test for Lp-PLA2

• Only FDA-cleared Dx for assessing risk for heart attack /ischemic stroke

– Large, addressable market of 60+ million adult Americans at moderate risk

– Strong and growing base business

• Projecting record sales in 2011 (guidance $15 - 16M)

• Q3 ‘11 revenue ($4.4) up 38% over Q3 ’10

– Broader reimbursement coverage

– Market expansion program to increase customers for PLAC® testing

Upside in new product: The “Activity” test.

– EU launch in 15 countries H1 2012

– Performance enhancements over ELISA-based Mass assay

– Foundation for entry into all clinical laboratories

Upside in personalized medicine

OTCBB: DDXS.OB