RepliGenNASDAQ: RGEN

Corporate Overview

October 2010

RepliGen

Company ProfileRepliGen

• Late-stage pipeline with significant market opportunity– RG1068 to diagnose pancreatitis; >$100M U.S./E.U. market (Phase 3)

– RG2417 for bipolar depression; ~$2B market opportunity (Phase 2b)

– Two potentially transformative drugs for orphan CNS diseases; >$500M marketopportunity each (Pre-clinical)

• Financial sustainability– Strong cash position (~$59M); low cash burn and no debt

– Profits from Bioprocessing business and royalties fund therapeutics pipeline

• Proven strategy– Acquired patent from MIT; developed Erbitux® cell line; licensed to ImClone for $65M

– Acquired patent from Univ. of Michigan; developed Orencia® application; licensed toBristol-Myers for ~$65M(e) in royalties through 2013

Repligen acquires product candidates, advances them to a key inflectionpoint and captures value by commercializing or partnering

Our goal for 2011 is to file an NDA in the U.S. and an MAA in the E.U. for RG1068,secure partner for RG2417; assuming positive data in Q1 2011

Advancing PipelineFueled by Commercial Assets

RepliGen

Pre-ClinicalAnimalModels

Phase 1First Human

Trial

Phase 2Proof of Concept

Phase 3Proof of

Efficacy

Market

RG2417Bipolar Disorder

RG2833 Friedreich’s Ataxia

RG1068Pancreatic Imaging

Orencia® RoyaltiesRheumatoid Arthritis

BioprocessingBusiness

Biologics Purification

Therapeutic ProductPipeline

Commercial Assets

RG3039 Spinal Muscular Atrophy

= FY2011 Goal (03/31/11)

~$13M inrevenue

~$10M inrevenue

FY2011(e)

CompletePhase 3

CompletePhase 2b

InitiatePhase 1

Qualify clinicalcandidate

Pancreatic Imaging

Pancreas

Liver

Bladder

Pancreas

Intestine

Post-RG1068

Pancreas

Liver

Bladder

Pancreas

Intestine

Pre-RG1068

Post-RG1068Pre-RG1068Clinical Application

4-6 minutes post-RG1068enhanced MRI leads to animproved image of ducts;diagnosis of pancreasdivisum which meanspatient is a candidatefor surgery

BiologyRG1068 stimulates therelease of fluid by thepancreas; filling thepancreatic ducts, whichmakes them larger

RG1068 Phase 3 Highlights

• ERCP is an invasive, risky endoscopic procedure for diagnosisof pancreatic duct abnormalities; associated with high morbidityand measurable mortality

• Patients in the Phase 3 study were evaluated for detection of 10pre-specified structural pancreatic abnormalities. MRI imagespre- and post-RG1068 were analyzed by three independentradiologists; ERCP used as “truth standard”

– Radiologists evaluation of data was flawed due to significant deviationsfrom the protocol

– FDA and EMA agreed to a “re-read” of images using three newradiologists

– Study showed that RG1068 aids in avoiding unnecessary ERCP; forevery patient on day of hospitalization from ERCP was saved

• Expect to complete Phase 3 re-read in Q1 2011• If successful, file New Drug Application (NDA) in Q2/Q3 2011

Phase 3 Results

52%

78%

34%

66%

35%

74%

46%

60%

Enhanced image quality and duct visualization results in improvedsensitivity to detect abnormalities and confidence in diagnosis

*Sensitivity data is for Reader 1 only

p<0.001p<0.001 p<0.001 p<0.001

Market Opportunity

• Market opportunity in U.S./E.U. for MRI enhancement is greater than

$100M, assuming a price of $350/vial

• Evaluating other clinical applications and market opportunity outside

of U.S./E.U.

– Surgery: improve confidence in diagnosis and pre-surgical planning

– New potential indication: pancreatic cancer detection/staging

– Japan is a third promising market; high utilization of MRI and potential for

favorable pricing

E.U.U.S.Clinical Application

TBD100,000Endoscopy

Expand market opportunity; triage to appropriatetherapy and convert diagnostic endoscopy to MRI

150,000200,000Abdominal MRI

Enhance existing MRI images

RG2417 for Bipolar Depression

• Bipolar disorder symptoms include episodes of severe

depression and mania; depressive episodes account for

majority of impairment

• Current therapies for bipolar depression are ineffective in

most patients and have significant side effects

• Bipolar disorder is linked to abnormal activity in the

mitochondria, the power plant of a cell

• RG2417, an oral formulation of uridine, may affect

mitochondrial activity and improve symptoms of depression

in bipolar disorder with minimal to no side effects

RG2417 Phase 2a Highlights

• Conducted a Phase 2a study resulting in statistically

significant improvement in depression on MADRS scale

– RG2417 well tolerated by patients; the adverse event profile for

RG2417 was equivalent to placebo

• Completed enrollment of Phase 2b study to confirm

Phase 2a results

• Expecting results from the Phase 2b study in the first

quarter of 2011

• Objective: license to a pharmaceutical partner in 2011

Phase 2a Results

All Patients Significant History of Symptoms 15 depressive episodes (n=33)

MA

DR

S S

co

re

MA

DR

S S

co

re

P=0.01 (repeated measures) P<0.001 (repeated measures)

P= .03 .09 .01 .08 .22

Market Opportunity

• Patients primarily seek treatment for the depressive symptoms

– Physicians report that 77% of the time patients seek treatement for

depressive symptoms as opposed to mania symptoms

• Psychiatrists have a high level of dissatisfaction with current

bipolar depression therapies because they are ineffective in

most patients and may have significant side effects

• Total costs of bipolar disorder ~$45 billion per year (NIH est.)

– Accounts for more than 16 million visits to a physician each year and

approximately 150,000 hospitalizations

• Worldwide prevalence >5 million

• Approximately $2B market opportunity (10% market

penetration)

RG2833 for Friedreich’s Ataxia

• Friedreich’s ataxia is an orphan

disease characterized by progressive

loss of muscle function which leads to

incapacitation and loss of life

• Caused by a defective gene, which

results in low levels of Frataxin protein

• RG2833, an HDAC* inhibitor, is the

first compound to target activation of

the defective gene to increase

frataxin production

• >$500M market opportunityA 2.5 fold increase in

Frataxin levels may besufficient to arrestdisease progress

Fra

taxin

Pro

tein

Level

Patients HealthyCarriers

*Histone deacetylase inhibitors (HDAC inhibitors) are aclass of compounds that interfere with the function ofhistone deacetylase, which is related to gene expression

RG2833 Next Steps

• Initiate Phase 1 study following FDA approval

• Evaluate HDAC inhibitors in animal models of

Huntington’s disease and cognition

• Prosecute worldwide patent protection; composition

of matter patents; priority date May 2008

RG3039 for Spinal MuscularAtrophy

• Spinal Muscular Atrophy (SMA) is an orphan disease characterized by

progressive loss of muscle function and early death in most patients

• Caused by a defective gene SMN2, which results in low levels SMN protein

• RG3039, is the first compound to target activation of the defective gene;

increasing the production of SMN and potentially arresting the progress of

the disease

• >$500M market opportunity

A 1.5 to 2 fold increase in SMN levels has the potential to profoundlyaffect the course of the disease

50% of patients have 3 copies

and 45% have 4 copies

82% of patients have 3 copies

73% of patients have 2 copies

SMN2 Gene Copy

50 YearsSMA III

~20 YearsSMA II

Life ExpectancyDisease Classification

SMA I ~2 Years

RG3039 Next Steps

• Qualify RG3039 as a clinical candidate

– Complete GLP toxicology study to determine

appropriateness for human clinical trials

• Initiate Phase 1 study

• Seek funding from non-profits or NIH

• Prosecute composition of matter patent

• For over 20 years, Repligen has been a leading supplier

of Protein A for production of monoclonal antibodies;

important therapies for cancer, autoimmune diseases

and osteoporosis

– OEM supply to GE Healthcare and Millipore

– FY2011 estimated revenue = ~$13M; 60% gross margin

• Repligen’s objective is to expand bioprocessing market

opportunity by broadening its product offering, and

through direct sales to end users

– Protein A Resins

– Pre-packed Columns

– Analytical Tools

Bioprocessing Overview

Plug & PlayChromatography

Expanding Market Opportunity

Protein AOEM suppliers

• GE Healthcare• Millipore

End-users•Monoclonals

Protein A Resins

MembranesAnalytical Tools

End-users•Monoclonals •Biologics •Vaccines

Market Size $25M

Market Size $500M

Protein A

Legacy Business

Emerging Business

Protein AResins

Pre-PackedColumns

Bioprocessing Business

Large Scale Fermentation Large Scale Purification

“Plug and Play” Opus™Columns

Analytical ToolsELISA Kits

rProtein AAffinity Resin

Projected Orencia® Royalties

Upfront paymentfor back-royalties

FY2011-FY2014 ~ $45M (e)

$6.3

$7.0

$13.3

$9.0

$10.3

$11.5

$12.8

$10.5

Licensed patent to Bristol-Myers for US sales of Orencia®, a noveltherapy for rheumatoid arthritis

Corporate AssetsRepliGen

Pre-ClinicalAnimalModels

Phase 1First Human

Trial

Phase 2Proof of Concept

Phase 3Proof of

Efficacy

Market

RG2417Bipolar Disorder

RG2833 Friedreich’s Ataxia

RG1068Pancreatic Imaging

Orencia® RoyaltiesRheumatoid Arthritis

BioprocessingBusiness

Biologics Purification

Therapeutic ProductPipeline

Commercial Assets

RG3039 Spinal Muscular Atrophy

= FY2011 Goal (03/31/11)

~$13M inrevenue

~$10M inrevenue

FY2011(e)

CompletePhase 3

CompletePhase 2b

InitiatePhase 1

Qualify clinicalcandidate

$104MMarket Cap (10/04/10)

32.2MShares & Vested Options (03/31/10)

30.8MShares Outstanding (03/31/10)

EOY Cash*

Net Loss

Revenue

Ending:

$57-58M$59.1M

(<$3M)($4.1M)

$24-26M$21M

3/31/20113/31/2010

FY2011(e)FY2010(a)

FinancialsRepliGen

* Net of acquisitions

45,00090 Day Average Volume (10/04/10)

Upcoming News StreamRepliGen

• September 2010: End of enrollment for RG2417Phase 2b study

• November 2010: Presenting at Society forNeurosciences on new indications for HDAC inhibitors

• November 2010: Q2FY11 results and quarterly update

• Q1 of 2011: Release RG1068 Phase 3 results

• Q1 of 2011: Release RG2417 Phase 2b study results

• H1 of 2011: Initiate phase 1 study of RG2833

• H1 of 2011: File IND for RG3039

Why Invest in Repligen?RepliGen

• Expecting data on a phase III development compound asMRI contrast agent for the diagnosis of pancreatic ductabnormalities in Q1, 2011

• Expecting data on a Phase II development compound forbipolar disorder Q1, 2011

• ~$3 stock with $1.50/share in cash. Cash burn is lessthan $0.10/share for 2011. No debt.

• Knowledgeable of monoclonal antibody productionprocess; holds 50% market share of protein A market

Business DriversRepliGen

Advance Pipeline AccelerateBioprocessing

Low Cash BurnProtect

Innovation

ShareholderValue

RepliGen

Potential Back Up Slides

Strategic Track Record RepliGen

Capture ValueDevelopedAcquired Captured Value

Compounds for cancer Erbitux® cell line Licensed to ImClone;$65Mtreatment from MIT for National Cancer Institute settlement

Compounds for RA Orencia® cell line Licensed to Bristol-Myers;From Univ. of Michigan Conducted early clinical trials ~$65M in royalties through 2013

Compounds for Friedreich’s Filed New Drug Application Continue developing to captureAtaxia from Scripps Research for RG2833 value as appropriate

Compounds for SMA from Identified clinical candidate Continue developing to captureFamilies for SMA RG3039 value as appropriate

Secretin for CNS diseases Completed Phase 3 study Commercialize (US) / Partner (EU);from Univ. of Maryland for pancreatic imaging following FDA approval

Uridine as treatment for Completed Phase 2a study Following positive results, qualifyBipolar Disorder Conducting a Phase 2b study potential partners

Present and Future

Past

Phase 3 Trial and Results

• One out of the three radiologists achieved primary endpoints

– 256 additional days of hospitalization with ERCP

• RG1068 well tolerated and safe vs. ERCP

• All three radiologists achieved secondary endpoints

Results

• Radiologists evaluation of data was flawed due to significantdeviations from the protocol

• Food and Drug Administration (FDA) and European Medicines Agency(EMA) agreed to a “re-read” of images using three new radiologists

Status

• Improvements in image quality, visualization of pancreatic ducts and

confidence in diagnosis of abnormalitiesSecondary Endpoints

• Statistically significant improvements in the detection of structural

abnormalities using RG1068 enhanced MRI vs. MRI alone, with no

false positivesPrimary Endpoints

• 258 patients were evaluated with MRI and ERCP for detection of 10

pre-specified structural abnormalities

– ERCP used as “truth standard” for abnormalities

– MRIs analyzed by three independent radiologists

Trial Protocol

Phase 2a Clinical Trial

• Statistically significant improvement in depression on

MADRS scale

• Well tolerated by patients; the adverse event profile for

RG2417 was equivalent to placebo

• Clinical benefit demonstrated primarily in patients with

moderate-severe disease history

Results

• Statistically significant decreases in the symptom of

depression as measured by the Montgomery Asberg

Depression Rating Scale (MADRS) with minimal

side effects

• MADRS has been previously accepted by the FDA for

drug approvals in bipolar depression

Primary Endpoint

A study with 83 patients, placebo-controlled, daily dosingand weekly assessment for 6 weeksProtocol

RepliGen

This presentation contains forward-looking statements which are made pursuant to the safe harborprovisions of Section 21E of the Securities Exchange Act of 1934. The forward-looking statements in thispresentation do not constitute guarantees of future performance. Investors are cautioned that statements inthis presentation which are not strictly historical statements, including, without limitation, statementsregarding current or future financial performance, management's strategy, plans and objectives for futureoperations, clinical trials and results and product development and manufacturing plans and performancesuch as the anticipated growth in the monoclonal antibody market and projected growth in product sales,constitute forward-looking statements. Such forward-looking statements are subject to a number of risks anduncertainties that could cause actual results to differ materially from those anticipated, including, withoutlimitation, risks associated with: the success of current and future collaborative relationships, the marketacceptance of our products, our ability to compete with larger, better financed pharmaceutical andbiotechnology companies, new approaches to the treatment of our targeted diseases, our expectation ofincurring continued losses, our uncertainty of product revenues and profits, our ability to generate futurerevenues, our ability to raise additional capital to continue our drug development programs, the success ofour clinical trials, our ability to develop and commercialize products, our ability to obtain required regulatoryapprovals, our compliance with all Food and Drug Administration regulations, our ability to obtain, maintainand protect intellectual property rights for our products, the risk of litigation regarding our intellectualproperty rights, our limited sales and manufacturing capabilities, our dependence on third-partymanufacturers and value added resellers, our ability to hire and retain skilled personnel, our volatile stockprice, and other risks detailed in Repligen's filings with the Securities and Exchange Commission. Repligenassumes no obligation to update any forward-looking information contained in this presentation or withrespect to the announcements described herein.

Safe Harbor