Filed by Vertex Pharmaceuticals Incorporated Pursuant to Rule 425 under the Securities Act of 1933 Subject Company: Aurora Biosciences Corporation Commission File Number: 000-22669 The following communications contain forward-looking statements within the meaning of the Safe Harbor Provisions of the Private Securities Litigation Reform Act of 1995 about Vertex Pharmaceuticals Incorporated and Aurora Biosciences Corporation. While the management of Vertex and Aurora make their best efforts to be accurate in making forward-looking statements, any such statements are subject to risks and uncertainties that could cause actual results to vary materially. The forward-looking statements herein address the following subjects: the intended accounting treatment of the merger between Vertex and Aurora, the expected annual rate of new drug candidates and Vertex's future drug development capabilities, the expected development schedule/goals of Vertex's current drug candidates and the expected benefits of the merger between Vertex and Aurora including (i) creating a competitive advantage in product development, (ii) accelerating drug discovery, (iii) entering into additional target rich gene families, (iv) maintaining low attrition rate in drug discovery, (v) expanding base of commercial partnerships, (vi) expanding organization without increasing burn and (vii) expanding Chemogenomics into multiple target classes. The following factors, among others, could cause actual results to differ materially from those described in the forward-looking statements: costs related to the merger, failure of Vertex's or Aurora's stockholders to approve the merger, the risk that the expected benefits of the merger may not be realized, third parties may terminate or alter existing contracts with Aurora if the required consents and waivers are not obtained or, in some cases, without cause, risks associated with Aurora's new and uncertain technology, the risk Vertex will not successfully develop its drug pipeline, the risk Vertex is unable to attract and retain collaborative partners for research support and the development and commercialization of its products, the risk Vertex does not obtain regulatory approval for its products on a timely basis, the risk Vertex loses its technological advantages, the risk Vertex fails to manage its growth effectively, the risk Vertex's competitors bring superior products to market or bring their products to market before Vertex does, and if Vertex patents do not protect its products, or Vertex's products infringe third-party patents, Vertex could be subject to litigation and substantial liabilities. For a more detailed discussion of such factors and other factors that may impact on such statements' accuracy, see the "Risk Factors" section of the definitive joint proxy statement/prospectus regarding the proposed merger as filed with the Securities and Exchange Commission. ******************** THE FOLLOWING IS THE TEXT OF SLIDES FROM A SLIDE SHOW PRESENTATION PRESENTED TO INVESTORS AND OTHERS ON JUNE 20, 2001 Vertex Pharmaceuticals Incorporated Vertex Pharmaceuticals Acquisition of Aurora Biosciences Joshua Boger, Ph.D., Chairman & CEO Lynne Brum, VP, Corp Comm. and Market Development June 2001 www.vrtx.com [Vertex Logo] Transaction Summary SUMMARY OF PROPOSED TERMS Companies Vertex Pharmaceuticals and Aurora Biosciences ---------------------- --------------------------------------------------------- Transaction Value $592 million ---------------------- --------------------------------------------------------- Structure/ Intended Tax-free stock-for-stock merger/ Accounting Treatment Pooling-of-interests ---------------------- --------------------------------------------------------- Name of Merged Entity Vertex Pharmaceuticals ---------------------- --------------------------------------------------------- Exchange Ratio 0.62 Vertex shares for each Aurora share ---------------------- --------------------------------------------------------- Ownership of Vertex 81.5%, Aurora 18.5%; proforma combined entity fully diluted ---------------------- --------------------------------------------------------- Shareholder Approval Required for both companies ---------------------- --------------------------------------------------------- Strategic Rationale The agreement creates a comprehensive, scalable platform for accelerating drug candidate output in target-rich gene families by combining: - Vertex's integrated drug discovery expertise with - Aurora's industry-leading assay development, screening, and cell biology capabilities, which drive its target-focused drug discovery efforts [Aurora and Vertex Logos] Outstanding Product Creation Capability AURORA VERTEX - Cell Biology - Drug discovery - Screening - Chemogenomics - Ultra high- - Drug development throughput systems - Broad pipeline - Target families - Commercialization - Cellular markers for clinical proof-of-concept - Financial strenth - Partners - Partners COMPETITIVE ADVANTAGE: PRODUCT DEVELOPMENT Immediate Benefits - Accelerate drug discovery - Entry to additional target rich gene families - Maintain low attrition rate in drug development - Expand base of commercial partnerships - Expand organization without increasing burn [Aurora and Vertex Logos] Vertex: Creating Value - Broad and deep clinical pipeline - 12 product candidates addressing four major areas - 1 product, Agenerase(R), on the market - Vitality in drug discovery - chemogenomics - Aurora Biosciences acquisition - Robust business model Vertex 2.0: Re-Creating Drug Discovery - Chemogenomics strategy is accelerating drug discovery in [GRAPHIC] gene families - Early returns in kinases fueling strategy to expand into additional gene families [GRAPHIC] - Integration of new technologies and capabilities Vertex Drug Discovery Platform Highly Integrated Approach X-ray/NMR [AURORA LOGO] High Throughput Computational Chemistry Screening & Modeling Enzymology Combinatorial [DRUG & Medicinal CANDIDATE Chemistry GRAPHIC] [AURORA LOGO] Molecular & Pharmacology, Cellular Biology Animal Models & Toxicology Genomics [DELTAGEN LOGO] [INCYTE LOGO] [VERTEX LOGO] [AURORA LOGO] Uniquely Positioned to Accelerate Drug Discovery JUNE 2001 Aurora Business Focus [AURORA LOGO] Discovery Discovery Discovery Biology Solutions Systems - Assay data-driven approach - Solutions for - Invent, develop, - Miniaturized drug discovery manufacture functional assays - Genome Screen/ and integrate applicable to all GeneBLAzer instrumentation major target classes - Voltage / Ion and software - Cell-based and Probe Reader (VIPR) systems for drug biochemical formats - PhosphoryLIGHT discovery - Rapid assay - Fluorescent - Systems include development Proteins (GFPs) - UHTSS - Applicability to - Automated Master orphan targets Compound Store - Protein purification - Voltage Ion Probe - Proteomics Reader Aurora: Key Capabilities o Drug discovery solutions based on proprietary genomic, assay and automated system technologies o Industry leader in custom assay development, ultra high-throughput screening o Broadly enabling technology with initiatives in multiple gene families including GPCRs and Ion channels o Compound profiling of ADME/Tox properties o Experienced scientific team o Strong business model/partnerships Expanding Chemogenomics into Multiple Target Classes [TARGET CLASSES GRAPHIC] [Aurora and Vertex Logos] Aurora Targets, Screens and Therapeutic Areas Ion 25 Targets, 10 screens Channels Cardiovascular, CNS, pain, cystic fibrosis Receptors 100 Targets, 20 screens CNS, inflammation, pain, antimicrobial Enzymes 100 Targets, 30 screens Cancer, inflammation, neurodegenerative Gene 15 Targets, 8 screens Expression Cancer, immune, metabolism Target Classes of Marketed Drugs* Vertex Alone Vertex with Aurora [VERTEX ALONE TARGET CLASSES GRAPHIC] [VERTEX WITH AURORA TARGET CLASSES GRAPHIC] 36% of top marketed drugs target enzymes With Aurora, Vertex's drug discovery platform addresses all major target classes *Based on top 100 marketed drugs **vaccines, imaging agents, and coagulation factors Achieving a New Level of Value Creation [DRUG CANDIDATES GRAPHIC] Annual Rate of New Drug Candidates Combined Patent Estate 135 Patents Issued or Allowed - Patent Protection for: - Drug candidates - "Drug space" in the active sites of novel targets - Innovative methods for drug discovery 193 Patents Pending Vertex: Robust Business Model - Competitive advantage in drug discovery - Chemogenomics: ramping up single target success into gene family approach - Innovative business model based on a balanced commercial strategy - Bring drugs forward independently and with partners - Revenue generation from partners and products - Strong downstream economics in partnerships - Commercial experience - Sustainable growth strategy Vertex: $1.4 Billion in Partner Committments Partner Date Value Capture Product Stage Kissei(HIV) 1993 1,6 Prozei(TM) Market Aventis 1993/1999 1,3,4 VX-740 Phase II GlaxoSmithKline 1993 1,3,6 Agenerase(R) Market 1,3,6 VX-175 Phase III Kissei(p38) 1997 1,6,7 VX-745 Phase II 1,6,7 VX-702 Preclinical Lilly 1997 1,3,4,6 VX in 2001* Schering 1998 1,2,6 Timcodar Phase II Taisho 1999 1,6,7 VX in 2001* Novartis 2000 1,3 2 VX in 2001* Serono 2000 1,2,3,5,6 VX in 2001* 1 High royalties 4 Co-promotion support 2 Profit sharing, JV 5 Sales, marketing 3 Co-promotion, co-labeling 6 Manufacturing rights *Anticipated Timing 7 Manufacturing agreement effectively includes includes high royalty World Class Partners- Vertex [LOGOS OF VERTEX'S WORLD CLASS PARTNERS] World Class Partners- Aurora [LOGOS OF AURORA'S WORLD CLASS PARTNERS] World Class Partners- Vertex and Aurora [LOGOS OF VERTEX'S AND AURORA'S WORLD CLASS PARTNERS] Vertex Pharmaceuticals Incorporated Vertex Pharmaceuticals Acquisition of Aurora Biosciences [VERTEX LOGO] Joshua Boger, Ph.D., Chairman & CEO Lynne Brum, VP, Corp Comm. and Market Development June 2001 www.vrtx.com [VERTEX LOGO] FOUR THERAPEUTIC AREAS; 12 DRUG CANDIDATES Product Indication Dev. Stage Partners ------- ---------- ---------- -------- Infectious Disease Agenerase(R) HIV Market GSK/Kissei VX-175 HIV Phase III GSK merimempodib (VX-497) HCV Phase II ------------ ---------- ---------- ---------- Cancer Incel(TM) MDR Phase II VX-853 MDR Phase I/II ------------ ---------- ---------- ---------- Inflammation & Autoimmune VX-745 Rheum. arthritis (RA) Phase II Kissei Disease VX-850 & VX-702 Inflammation, cardio Preclinical Kissei pralnacasan (VX-740) RA, OA, cardio Phase II Aventis VX-765 Inflammation, cardio Preclinical VX-148 Autoimmune,antiviral Phase I VX-944 Autoimmune,antiviral Preclinical -------------------- -------------------- ------------ ------------ Neurological Disease timcodar Diabetic neuropathy Phase II Schering AG Gene Family Discovery: Long-Term Outlook [VERTEX'S LONG-TERM PRODUCTS] Gene Family Discovery: Product Vision [VERTEX'S PRODUCT VISION] The Post-Genomic NCE Machine Industry Leading Drug Discovery - Vertex: Chemogenomics, structure-based drug design, multi-target gene family drug discovery - Aurora: Ultra-high-throughput screening, assay development Complementary Strategy - Vertex and Aurora: Combine scalable approaches to accelerate drug discovery to maximize product creation based on gene families Technological Fit - Vertex: Gains access to leading biology capabilities in gene families - Aurora: Gains immediate fulfillment of downstream goals of Big Biology initiative Common Goals - Vertex and Aurora: Leader in drug discovery and development: Creating the Post-Genomic NCE Machine Vertex and Aurora: Global Operation Approximately 825 Employees Worldwide - Cambridge, MA - Worldwide headquarters [Facility Graphic] - San Diego, CA - Madison, WI [Facility Graphic] - Oxford, UK [VERTEX LOGO] [AURORA LOGO] Uniquely Positioned to Accelerate Drug Discovery APRIL 2001 ******************** Investors and security holders are advised to read the joint proxy statement/prospectus regarding the proposed merger as filed with the Securities and Exchange Commission, because it contains important information. Such joint proxy statement/prospectus has been filed with the Securities and Exchange Commission by Vertex and Aurora. Investors and security holders may obtain a free copy of the joint proxy statement/prospectus and other documents filed by Vertex and Aurora at the Securities and Exchange Commission's web site at www.sec.gov. The joint proxy statement/prospectus and such other documents may also be obtained from Vertex by directing such request to Vertex Pharmaceuticals, 130 Waverly Street, Cambridge, MA 02139, Attn: Investor Relations, tel: (617) 577-6000; e-mail: InvestorInfo@vpharm.com. The joint proxy statement/prospectus and such other documents may also be obtained from Aurora by directing such request to Aurora Biosciences, 11010 Torreyana Road, San Diego, CA 92121, Attn: Investor Relations, tel: 858-404-6600; e-mail: ir@aurorabio.com. Vertex and Aurora and their respective directors, executive officers and certain members of management and employees may be soliciting proxies from Vertex and Aurora stockholders in favor of the adoption of the merger agreement and the transactions associated with the merger. A description of any interests that Vertex and Aurora directors and executive officers have in the merger are available in the joint proxy statement/prospectus. ********************