From New Mechanisms to New Standards of Care Corporate Presentation - PowerPoint PPT Presentation

From New Mechanisms to New Standards of Care Corporate Presentation August 2019

Forward-Looking Statements Statements in this presentation, other than statements of historical fact, constitute forward-looking statements within the meaning of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include statements regarding Summit’s clinical trials supporting the safety and efficacy of its product candidates and the potential novelty of such product candidates as treatments for disease, plans and objectives for preclinical studies, clinical trials, product development and regulatory filings, Summit’s collaboration with Eurofarma Laboratorios SA, Summit’s award from BARDA, Summit’s Discuva Platform, strategies, future performance, expectations, assumptions, financial condition, liquidity and capital resources. These forward-looking statements may be preceded by, followed by or otherwise include the words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions. Actual results or events may differ materially from those expressed or implied in any forward-looking statements due to various factors, including the risks and uncertainties inherent in clinical trials and product development and commercialization, such as the uncertainty in results of clinical trials for product candidates, the uncertainty of whether the preliminary results from a clinical trial will be predictive of final results of that trial or whether the results of clinical trials will be predictive of results in later stages of product development, the risk of delays or failure to obtain or maintain regulatory approval, the risk of failure of the third parties upon whom Summit relies to conduct its clinical trials and manufacture its product candidates to perform as expected, the risk that any third-party collaborator, including Eurofarma, terminates or fails to meet its obligations to Summit, the risk of the ability of BARDA to terminate our contract for convenience at any time, the risk that Summit’s discovery and development platform may not identify new potential drug development candidates, the risk of increased cost and delays due to delays in the commencement, enrollment, completion or analysis of clinical trials or significant issues regarding the adequacy of clinical trial designs or the execution of clinical trials and the timing, cost and design of future clinical trials and research activities, the timing of expected filings with the FDA or other regulatory agencies; and the other risks and uncertainties described in Summit’s public filings with the Securities and Exchange Commission. Summit may not actually achieve the plans, intentions or expectations disclosed in its forward-looking statements, and you should not place undue reliance on its forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in forward-looking statements. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. Summit disclaims any intent or obligation to revise or update these forward-looking statements, except as required by applicable law. 2 Company presentation August 2019

Urgent Need for New Antibiotics Provides Major Opportunity Poor patient outcomes and increasing resistance with existing classes of antibiotics THE CHALLENGE THE SUMMIT SOLUTION Focus on Recent launches have disappointed differentiation • No new classes of antibiotics: incremental • Develop new classes of antibiotics with changes fail to combat emerging drug distinctive features and benefits resistance • Target the infection or pathogen to restore health • Failure to address clear unmet patient needs • Address measurable unmet medical need • No compelling medical evidence: non- inferiority trials don’t show clear patient • Show superiority in patient outcomes to benefit establish compelling use case • No economic data to justify use of premium • Demonstrate value of new antibiotics priced treatments over cheap generics through economic data 3 Company presentation August 2019

Summit’s Approach: Innovation for the Patient Translating novel science into differentiated products delivered to the patient DISCOVER • New classes of antibiotics • Distinctive features and benefits • Targeted spectrum preserves microbiomes • Less prone to rapid resistance development PATIENT DEVELOP UNMET • Clinical trial designs to test for unmet need • Outcomes show superiority over standard of care NEED • Health economic measures demonstrate value of improved outcomes COMMERCIALIZE • Patients offered solution to unmet need • Physicians have data to switch therapy • Payors have data showing economic value • Strong stewardship case to use new drugs 4 Company presentation August 2019

Our New Mechanism Antibiotic Pipeline Phase 3 Preclinical Phase 1 Phase 2 Threat Status Discovery Urgent CDI (Ridinilazole) 1 (CDC) Gonorrhea Urgent / High (SMT-571) (CDC / WHO) Urgent / High Enterobacteriaceae (DDS-04 Series) (CDC / WHO) Urgent / High ESKAPE (CDC / WHO) Program Gonorrhea Urgent / High (Target #2) (CDC / WHO) Discuva Platform A portfolio created with assistance: BARDA, CARB-X, Innovate UK & Wellcome Trust 5 1. We own worldwide rights to ridinilazole, outside of certain Latin American countries and Caribbean islands. Company presentation August 2019

About C. difficile Infection (CDI) >1.0m cases Initial treatment Failure likely per year in US fails to cure or connected to and EU 1 , 29,000 sustain cures in impact on deaths per year around a third microbiome of in the US 2 of cases standard of care 6 1. Decision Resources, 2015 Company presentation 2. New England Journal of Medicine, 2015 August 2019

Ridinilazole Designed to be Patient-Friendly Clear differentiation in Phase 2 trial supports new standard of care potential Cured CDI and sustained cures over 40 days  60% reduction in recurrences, the key unmet need  Superiority over standard of care vancomycin in sustained cures  Discharged from hospital earlier Gut-friendly Improved physical & mental  Treatment preserved effects of CDI microbiome and allowed  Resolved diarrhea earlier good bacteria to recover  Significantly reduced pain/discomfort  Well-tolerated, as  Significantly reduced anxiety/depression treatment targeted to gut Initiated global Phase 3 clinical trials Feb. 2019 Expect top-line data H2 2021 With positive results, expect NDA filing 2022 7 Source: CoDIFy Phase 2 clinical trial Company presentation August 2019

Aiming for Dominant Position in Front-Line Treatment Goal of Phase 3 clinical trials is to show clear benefits of ridinilazole • A more effective treatment option PATIENT • High cure rate with low recurrence • Well tolerated with preservation of the microbiome • A more effective treatment option PHYSICIAN • Statistical superiority over vancomycin, the standard of care • High cure rates with low recurrence • Premium pricing supported by total cost of care savings PAYOR • Fewer expensive recurrences ESTIMATED • Fewer readmissions help meet CMS targets SAVINGS OF ~ $3,000- $6,100 Compelling data to support potential switch to front-line use of ridinilazole PER PATIENT IN THE US 1 1. Range based on management estimates of potential savings of front-line treatment reducing CDI recurrence derived from 8 Ghantoji et al., J Hosp. Infect 2010; Duberke et al., Infect Control Hosp Epidemiol 2014; Zhang et al., CID 2018; Zilderberg et al., Company presentation Medicine 2017; Desai et al., BMC Infect Dis 2016. Relevant studies identified in PubMed search July 2019, with reported/derived August 2019 recurrence costs adjusted to 2023 pricing using US CPI for years to 2018 and assumed 2% inflation 2019-2023 rate to 15%

Ridinilazole: Significant Commercial Potential in CDI ~ 450,000 COST OF RECURRENCE IN US APPROXIMATELY HOSPITALS 1 25% $11,400 - US PATIENTS TREATED ANNUALLY FOR HAVE A RECURRENCE. 1 st CDI INCIDENCE $23,200 RISK RISES TO 45% FOR SECOND, 65% FOR THIRD Estimated cost savings per US patient with first ~ $3,000-6,100 incidence treated, if recurrence rate was reduced by absolute 15% 2 Total potential cost savings ~ $1.4-2.7B to US healthcare system supports premium pricing 1. Range from Ghantoji et al., J Hosp. Infect 2010; Duberke et al., Infect Control Hosp Epidemiol 2014; Zhang et al., CID 2018; 9 Zilderberg et al., Medicine 2017; Desai et al., BMC Infect Dis 2016. Relevant studies identified in PubMed search July 2019, with Company presentation reported/derived recurrence costs adjusted to 2023 pricing using US CPI for years to 2018 and assumed 2% inflation 2019-2023 August 2019 rate to 15%; 2. Based on management estimates of potential savings of front-line treatment reducing CDI recurrence