Jefferies 2015 Healthcare

Conference

Paul J. HastingsChairman and Chief Executive Officer

June 2, 2015

2

Safe Harbor Statement

These slides and accompanying oral presentation contain forward-looking statements. All statements, other than statements of historical fact, included in these slides and accompanying oral presentation are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “could,” “will,” “would,” “should,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “intend,” “predict,” “seek,” “contemplate,” “potential” or “continue” or the negative of these terms or other comparable terminology. Forward-looking statements in these slides and accompanying oral presentation include, but are not limited to, statements about: the initiation, timing, progress and results of our preclinical studies and clinical trials, and our research and development programs; our ability to advance product candidates into, and successfully complete, clinical trials; the tolerability of our product candidates at efficacious doses; our collaborators’ exercise of their license options; the commercialization of our product candidates; the implementation of our business model, strategic plans for our business, product candidates and technology; the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates and technology; estimates of our expenses, future revenues, capital requirements and our needs for additional financing; the timing or likelihood of regulatory filings and approvals; our ability to maintain and establish collaborations or obtain additional government grant funding; our financial performance; and developments relating to our competitors and our industry.

These statements relate to future events or to our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the preclinical and clinical development process; the risks and uncertainties of the regulatory approval process; our dependence on our collaboration partners, including Celgene, GlaxoSmithKline and Bayer, for the funding of our partnered programs; our ability to raise additional capital to support the development of our unpartnered programs; our dependence on the development and marketing efforts of our partners for the commercial success of our partnered product candidates; our reliance on third parties to conduct certain preclinical studies and all of our clinical trials; our reliance on single source third-party contract manufacturing organizations to manufacture and supply our product candidates; our ability to validate, develop and obtain regulatory approval for companion diagnostics; our ability to achieve market acceptance and commercial success of our product candidates once regulatory approval is achieved; our ability to discover, develop and commercialize additional product candidates; the ability of competitors to discover, develop or commercialize competing products more quickly or more successfully; our dependence on our Chairman and Chief Executive Officer, our Chief Scientific Officer, our Chief Medical Officer and other key executives; risk of third party claims alleging infringement of patents and proprietary rights or seeking to invalidate our patents or proprietary rights; and the ability of our proprietary rights to protect our technologies and product candidates. Other factors that may cause actual results to differ materially from current expectations include, among other things, those listed under “Risk Factors” or otherwise described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014, filed with the Securities and Exchange Commission (SEC) on March 12, 2015 and our Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2015, filed with the SEC on May 7, 2015.

Any forward-looking statement you see or hear during this presentation reflects our current views with respect to future events and is subject to these and other risks, uncertainties and assumptions relating to our operations, results of operations, industry and future growth. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.

3

OncoMed Pharmaceuticals, Inc.

Proprietary

Discovery

Capabilities

• Targeting critical cancer stem cell and immuno-oncology pathways

• Pipeline of first-in-class anti-cancer stem cell therapeutics

• All discovered at OncoMed

Deep

Clinical

Pipeline

Strong

Long-Term

Outlook

• 6 clinical programs in or advancing to Phase 2

− 7th program IND filed

• 16 active clinical trials: evidence of activity

• Data from multiple randomized Phase 2 trials by 2016-17

• Partnerships with Celgene, Bayer and GSK

• Ongoing discovery research fueling pipeline

• Substantial future milestones and cash

4

Cancer Stem Cells Drive Tumor Growth,

Recurrence and Metastasis

CSC (7/8)

Other (0/10)

Day post-injection

Tu

mor

Volu

me (

mm

3)

Human

colon tumor

CD

44

CD166

CSCsC

D44

CD166

CSCs

Human

colon tumor growth

in mouse xenograft

FACS analysis of

human tumor in mouse

CSCs Drive Tumor Growth Anti-CSC Therapy Blocks Renewal;

Forces Differentiation

Self-renewal

Differentiation

5

RSPO/LGR

Pathway

Wnt

Pathway

Notch

Pathway

Targeting Critical Stem Cell Pathways

• Demcizumab

• Tarextumab

• Brontictuzumab

• Anti-DLL4/VEGF

bispecific

• Vantictumab

• Ipafricept

• Small

Molecules

• Anti-RSPO3

• Other RSPOs

• Other LGRs

New

Pathways

• Immunotherapy

• Hippo

• Undisclosed

6

Anti-Cancer Stem Cell Pipeline6 Clinical Programs, 5+ Research Programs

Therapeutic Preclinical IND Phase 1a Phase 1b Phase 2

DemcizumabAnti-DLL4; OMP-21M18

TarextumabAnti-Notch2/3; OMP-59R5

Vantictumabanti-Fzd7, OMP-18R5

IpafriceptFzd8-Fc; OMP-54F28

BrontictuzumabAnti-Notch1; OMP-52M51

Anti-DLL4/VEGFOMP-305B83

Anti-RSPO3OMP-131R10

Small MoleculesWNT inhibitors

Immunotherapy

Hippo Pathway

Small Molecules(Undisclosed)

CL

INIC

AL

PR

EC

LIN

ICA

L

Filed

7

Demcizumab (anti-DLL4) Inhibits

Tumor Growth by Three Distinct Mechanisms

Blocks critical DLL4 role in angiogenesis

Angiogenesis Immune ResponseCancer Stem Cells

Promotes differentiation and chemo sensitization

Blocking DLL4 function reduces CSC, inhibits tumor

angiogenesis and relieves immune suppression

Reduced IL-17 production Reduced monocyticmyeloid-derived suppressor cells (MDSCs)

8

Demcizumab Clinical Program

Phase 1a Advanced solid

tumors

Phase 1bPancreatic Cancer

Phase 2YOSEMITE

Pancreatic Cancer

Phase 1bNon-Small Cell

Lung

Phase 2DENALINSCLC

Single agent Combo with chemo Randomized

Enrolling

Currently

In Ph1b

Phase 1b/2Ovarian

Enrolling

• Multi-pronged MOA

• Single agent activity observed – partial and minor responses

• Generally well tolerated

− Truncated dosing mitigates cardiopulmonary toxicity

9

Demcizumab Phase 1b Pancreatic Cancer

Response Rates

89% Overall Clinical Benefit Rate

Demcizumab +

Abraxane + Gemcitabine* (N=29)

Abraxane +

Gemcitabine**

Partial Response 14 (50%) 23%

Stable Disease 11 (39%) 27%

Hidalgo, et al ASCO 2015 * Single arm study, unconfirmed responses

First-line Pancreatic Cancer (N=29)

Demcizumab + Gemcitabine + Abraxane

**MPACT Phase 3 study; Von Hoff, et al, NEJM 2013

% C

ha

ng

e in

Tu

mo

r S

ize

10

Demcizumab Phase 1b Pancreatic Cancer

Duration of Responses

Hidalgo, et al ASCO 2015

Progression-free Survival

Demcizumab + Abraxane + Gemcitabine

*Single arm study, unconfirmed responses **MPACT Phase 3 study; Von Hoff, et al, NEJM 2013

Pro

bab

ilit

y

Overall Survival

Demcizumab + Abraxane + Gemcitabine

mOS (95% CI) = 10.1 months (6.5 – 16.2)mPFS (95% CI) = 9.0 months (3.7– NR)

0 5 10 150 5 10 15

Survival Rates

Demcizumab +

Abraxane + Gemcitabine*

Abraxane +

Gemcitabine**

Progression-free Survival 9.0 months 5.5 months

Overall Survival 10.1 months 8.5 months

Months

Pro

bab

ilit

y

Months

11

Demcizumab Phase 1b NSCLC

Response Rates

89% Overall Clinical Benefit Rate

Demcizumab + Pemetrexed

+ Carboplatin (N=40)*

Pemetrexed +

Carboplatin**

Complete Response 1 (3%)

Partial Response 19 (48%) 27%

Stable Disease 15 (38%)

* Single arm study, unconfirmed responses ** Alimta® (pemetrexed) Package insert

First-Line Advanced NSCLC (N=40)

Demcizumab + Pemetrexed + Carboplatin

Kotasek, et al ASCO 2015

% C

ha

ng

e in

Tu

mo

r S

ize

12

NSCLC Overall Survival by Kaplan MeierPhase 1b Exploratory Analysis

% A

live

mOS (95% CI) = 6.3 months (3.2-NR)

Truncated Demcizumab Dosing

% A

live

mOS (95% CI) = 8.1 (5.8-NR) mos

Kotasek, ASCO 2015

Continuous Demcizumab Dosing

“Worst Case” Survival Analysis

Ten of 23 patients (~40%)

alive >2 years

0 10 20 30 40 50

Months

Months 0 5 10 15 20 25

Tumor Biomarker Analysis (%Tils)

%TILs ≤50%Ove

rall

Su

rviv

al

Survival days

% TILs >50%%TILs >50%

%TILs ≤50%

13

Tarextumab: Anti-Notch2/3 Antibody

Phase 1b/2

ALPINE StudyPancreatic Cancer

Phase 1b/2

PINNACLE StudySmall Cell Lung Cancer

Single agent Combo with chemo Randomized

Phase 1a Advanced solid tumors

Phase 1b/2

ALPINEPancreatic

Phase 1b/2

PINNACLESmall Cell Lung Cancer

Enrolling

Enrolling

• Reduces CSCs; promotes differentiation

• Single agent activity

On-target, manageable GI toxicities

• Predictive biomarker program

− Notch3+ tumor status

14

Tarextumab Phase 1b ALPINE

Response Rates

73% Overall Clinical Benefit Rate

Tarextumab +

Abraxan+ Gemcitabinee* (N=24) Abraxane + Gemcitabine**

Partial Response 11 (38%) 23%

Stable Disease 10 (35%) 27%

PR + SD 21 (73%) 50%

O’Reilly, et al ASCO GI 2015

First-line Pancreatic Cancer (N=37)

Tarextumab + Abraxane + Gemcitabine

30% target tumor reduction

% C

ha

ng

e in

Tu

mo

r S

ize

= Tarextumab + Gemcitabine

= Tarextumab + Gemcitabine + Abraxane

*Single arm study, unconfirmed responses **MPACT Phase 3 study; Von Hoff, et al, NEJM 2013

15

Tarextumab Phase 1b ALPINE

Duration and Biomarker Data

O’Reilly, et al ASCO GI 2015

Tumor Notch3 Level and Timed Endpoints

Progression-free Survival and Overall Survival

Tarextumab + Gemcitabine +

Abraxane*mPFS (months) mOS (months)

All patients (N=24) 5.6 11.6

Notch3 high (50%) (N=12) 6.6 14.6

Gemcitabine + Abraxane** 5.5 8.5

14.6months

*Single arm study, unconfirmed responses **MPACT Phase 3 study; Von Hoff, et al, NEJM 2013

16

Tarextumab Phase 1b PINNACLE

Response Rates

100% Overall Clinical Benefit Rate (N=26)

Tarextumab +

Etoposide +

Carboplatin/Cisplatin

Cisplatin +

Etoposide**

Partial Response 20 (77%) 44%-67%

Stable Disease 6 (23%)

Pietanza, et al ASCO 2015 **SCLC Meta-Analysis; Rossi, et al, JCO 2012* Single arm study, unconfirmed responses

Extensive-stage SCLC (N=26)

Tarextumab + Etoposide + Cisplatin/Carboplatin

% C

ha

ng

e in

Tu

mo

r S

ize

17

Tarextumab Phase 1b PINNACLEBiomarker and Survival Analysis

Pietanza, et al ASCO 2015

Progression-Free Survival

Low Notch3 vs. High Notch3

Potentially longer survival noted in Notch3 high patients receiving higher

doses of tarextumab (≥12.5mg/kg) + platinum therapy

N=13Low Notch 3

N=12

Overall Survival

Low Notch3 vs. High Notch3

Low Notch 3

N=12

High Notch 3

N=13

High Notch 3

N=13

Months MonthsMonths Months

18

Brontictuzumab: Anti-Notch1 Antibody

Dose Escalation Expansion Cohort

Phase 1aAdvanced solid tumors

Phase 1aBiomarker selected

Phase 1aHematologic malignancies

Phase 1aBiomarker selected

Ongoing

dose escalation

Ongoing

expansion

• Anti-CSC, anti-angiogenic

• Single agent activity

On-target, manageable GI toxicities

• Predictive biomarker program

− IHC assay identifying solid tumors with Notch1 activation

19

Brontictuzumab Phase 1a

Solid Tumor Trial with Biomarker Assay

Patnaik, et al EORTC-NCI-AACR 2014

Predictive Biomarker (Notch1)

• 3 of 4 patients with Notch1 ICD high

tumors with clinical benefit

• 1 of 9 patients with Notch1 ICD low

tumors with clinical benefit

Notch1 High Notch1 Low Notch1 ?

Partial Response1 - -

Stable Disease2 1

Progressive

Disease 1 8 4

Total4 9 4

Responses among Evaluable Subjects (N=17)Phase 1a Expansion

Now Enrolling

Solid Tumor Types with

Notch1 ICD High

Prevalence (12%-53%)

• Colorectal

• Gastric

• Esophageal

• Pancreatic

• Small cell lung

• HER2- breast

• Cholangiocarcinoma

• Adenoid cystic carcinoma

20

Vantictumab (anti-Fzd7) WNT Pathway

Single agent

Phase 1aAdvanced solid tumors

Phase 1bHer2- Breast Cancer

paclitaxel

Phase 1bNSCLCdocetaxel

Phase 1bPancreatic Cancergemcitabine + Abraxane

Combo with chemo

• Inhibits Wnt signaling

− Blocks Frizzled 1, 2, 5, 7, 8

• On-target, mild-to-moderate bone-related AEs observed

− Bone protection strategy

• Single agent activity 3/3 neuroendocrine tumors

21

Ipafricept (Fzd8-FC) WNT Pathway

Single agent

Phase 1aAdvanced solid tumors

Phase 1bOvarian

carboplatin + paclitaxel

Phase 1bHepatocellular

sorafenib

Phase 1bPancreatic

gemcitabine + Abraxane

Combo with chemo

• Inhibits signaling: binds Wnt ligands

− Distinct from vantictumab

• On-target, mild-to-moderate bone-related AEs observed

− Bone protection strategy

• Single agent activity in diverse tumor types; SD > 112 days in 9 patients

22

• Dual inhibitor DLL4 & VEGF

• Multi-pronged MOA

• Preclinical data: improved efficacy and safety

• Phase 1a initiated December 2014

− Dose escalation, expansion

− Advanced, refractory solid tumors

Anti-DLL4/VEGF Bispecific (OMP-305B83)

Single agent

Phase 1aAdvanced solid tumors

Yen AACR 2014

Anti-DLL4

Heavy chain

Anti- VEGF

Heavy chain

23

New R&D Candidates

Anti-RSPO3 (OMP-131R10)

• IND filed April 2015

• Multiple therapeutic opportunities

– Strong predictive biomarker strategy

• Broad, issued claims cover therapeutic antibodies that disrupt RSPO-LGR signaling

Other Anti-RSPO candidates

• RSPO 1, 2, 4; LGR 4, 5, 6

Immuno-oncology

• Two novel immuno-oncology programs

– Hippo pathway (Celgene)

– GITR Ligand-Fc (OMED wholly owned)

• Discovery of “missing” checkpoint receptor to PD-L2

– OMED wholly owned

Gurney AACR 2014

RSPO

LGR

GITRL-Fc

24

3 Significant Partnerships Provide

Funding and Value

Partner Year Upfront Comments

2013 $177M*

• Up to 6 biologics + small molecules

• Co-development/commercialization on 5 of 6 biologics– Demcizumab end of Phase 2 opt-in

– Anti-DLL4/VEGF, RSPO3, others Phase 1 opt-in

– 1/3 OMED – 2/3 CELG development cost share

– 50-50 US profit share

– Ex-US royalties

• Celgene equity stake ~5%

2010 $40M

• Up to 3 biologic & 2 small molecule programs

• Opt-in through end of Phase 1b for vantictumab, ipafricept

• Mid-single digit to high teens royalties on biologics

2007,

2011$35M*

• 2 biologics programs

• Opt-in at end of Phase 2 for tarextumab

• Opt-in at end of Phase 1 or Phase 2 for brontictuzumab

• Low double-digit to high teens royalties

• GSK equity stake ~8.8%

*Celgene: $155M cash, $22.25 equity; GSK: $17.5M cash, $17.5M equity

Note: equity % stake per most recent SEC filing

25

Program Financial Milestone Snapshot

Program Potential Future Milestones/Payments

Demcizumab ~$790M

Tarextumab $319.5M

Vantictumab $357.5M

Ipafricept $347.5M

Brontictuzumab $330.5M

Anti-DLL4/VEGF bispecific ~$505M

Anti-RSPO3 ~$440M

RSPO/undisclosed pathway ~$440M each, up to 3

Bayer small molecules $110M

Celgene small molecules >$100M

Total Potential Milestones >$4 Billion

Over $378M* received to date from Celgene, Bayer, GSK

*Includes $5M receivable

26

Potential Collaborative Revenue 2015-16

Milestone/Payments Partner Amount Timing

Brontictuzumab Phase 1

expansion$5M 1H 2015

Demcizumab Phase 2 safety

analysis$70M Q4 2015/2016

Vantictumab opt-in $25M 2H 2015/2016

Ipafricept opt-in $15M 2H 2015/2016

Brontictuzumab opt-in $18.75M2H 2015/2016Payment increases to $25M if GSK

chooses to wait to opt in at Phase 2

Tarextumab opt-in $25M 2016

Total Potential Milestones >$150M Through 1H 2016*

* Additional milestones could be achieved in 2015/2016 related to preclinical and small molecule programs

27

OMED Financial Guidance

• Cash*: $213M as of March 31, 2015

• 2015 Financial Guidance:

– $100 - $110M cash operating expenses, excluding non-cash expenses

– YE cash of over $120M before potential milestone payments

• $150M+ in potential 2015/16 payments from existing partnerships

• Existing cash plus future milestones may fund operations through commercialization without need for future financing

* Cash, equivalents, and short-term investments; unaudited

28

2015 Pipeline Progress

1H 2015

ClinicalDataFinancial/Corporate*

2H 2015

Anti-DLL4/VEGF Phase 1a FPI

ASCO GI - TarextumabFinal Phase 1b pancreatic; biomarker

Demcizumab NSCLC Phase 2 FPI

Demcizumab Pancreatic Phase 2 FPI

Phase1a Brontictuzumab expansion

File anti-RSPO3 IND

ASCO - DemcizumabPhase 1b Pancreatic & NSCLC

ELCC - DemcizumabUpdated Phase 1b NSCLC data

ASCO - TarextumabPhase 1b SCLC

Present opt-in package to BayerVantictumab & ipafricept

Present Phase 1a Brontictuzumab dataBiomarker-selected expansion cohort

Present Ipafricept data

Complete Demcizumab Phase 1bOvarian

Demcizumab Phase 2 safety analysis

Present Vantictumab data

Complete Tarextumab Phase 2

enrollment in pancreatic cancer

* Select financial milestones

Anti-RSPO3 Phase 1a FPI

2015 /

2016

AACR7 abstracts accepted for presentation

R&D Investor DayApril 29 in NYC

29

OncoMed Pharmaceuticals, Inc.

Proprietary

Discovery

Capabilities

• Targeting critical cancer stem cell and immuno-oncology pathways

• Pipeline of first-in-class anti-cancer stem cell therapeutics

• All discovered at OncoMed

Deep

Clinical

Pipeline

Strong

Long-Term

Outlook

• 6 clinical programs in or advancing to Phase 2

− 7th program IND filed

• 16 active clinical trials: evidence of activity

• Data from multiple randomized Phase 2 trials by 2016-17

• Partnerships with Celgene, Bayer and GSK

• Ongoing discovery research fueling pipeline

• Substantial future milestones and cash

Thank you