Enanta Pharmaceuticals Reports Financial Results for its Fiscal Third Quarter Ended

Enanta Pharmaceuticals Reports Financial Results for its

Fiscal Third Quarter Ended June 30, 2015

Conference Call and Webcast Today at 4:30 p.m. ET

WATERTOWN, Mass., August 6, 2015 Enanta Pharmaceuticals, Inc., (NASDAQ: ENTA), a research and development-focused biotechnology company dedicated to

creating small molecule drugs for viral infections and liver diseases, today reported financial results for its fiscal third quarter ended June 30, 2015.

Fiscal Third Quarter Ended June 30, 2015 Financial Results

Cash, cash equivalents and short-term and long-term marketable securities totaled $212 million at June 30, 2015. This compares to a total of $132 million

in such accounts at September 30, 2014. Enanta expects that its current cash, cash equivalents and marketable securities will be sufficient to meet the anticipated cash requirements of its existing business for the foreseeable future.

Revenue for the three months ended June 30, 2015 was $11.6 million, compared to $42.1 million for the three months ended June 30, 2014. For the 2015

quarter, revenue consisted primarily of royalties earned on a contractually specified portion of AbbVie s worldwide net sales of hepatitis C virus (HCV) treatment regimens containing paritaprevir, Enanta s lead protease inhibitor

identified within the ongoing AbbVie-Enanta collaboration. The higher revenue in the comparable quarter in 2014, when Enanta had no royalty revenue, consisted primarily of milestone payments from AbbVie totaling $40 million related to regulatory

filings in the U.S. and EU. For the nine months ended June 30, 2015, revenue was $146.5 million, compared to revenue of $45.1 million for the same period in 2014. The increase in revenue for the nine months ended June 30, 2015 was due

primarily to a total of $125 million in payments earned from AbbVie for the achievement of U.S. and EU commercialization regulatory approvals of VIEKIRA PAK and VIEKIRAX , respectively,

as well as to royalties earned on those products. Milestone payments, royalties and other payments from collaborations have varied significantly from period to period, and are expected to continue to do so.

Research and development expenses totaled $6.3 million for the three months ended June 30, 2015, compared to $4.6 million for the three months ended

June 30, 2014. For the nine months ended June 30, 2015, research and development expenses were $16.1 million, compared to $13.5 million for the same period in 2014. The increases in the three and nine month periods over the prior year

periods were primarily due to increased spending on Enanta s proprietary research programs.

General and administrative expenses totaled $3.6 million for the three months ended June 30, 2015, compared

to $2.6 million for the three months ended June 30, 2014. For the nine months ended June 30, 2015, general and administrative expenses totaled $9.9 million, compared to $7.3 million for the same period in 2014. The increases in the three

and nine month periods primarily reflected increases in stock-based compensation expense, due principally to increases in Enanta s stock price, as well as additional expenses incurred as Enanta expands its operations.

Net income for the three months ended June 30, 2015 was $2.4 million, or $0.13 per diluted common share, compared to $50.1 million, or $2.61 per diluted

common share, for the corresponding period in 2014. The net income in the 2014 quarter reflected not only a total of $40 million in milestone payments for regulatory filings, but also the reversal of the entire valuation allowance related to

Enanta s deferred tax assets, which resulted in an income tax benefit of $15.1 million in the quarter. For the nine months ended June 30, 2015, net income was $73.2 million, compared to $39.5 million for the same period in 2014. The

increase in net income during the nine month period ended June 30, 2015 was primarily due to $125 million in milestone payments received, as well as royalty revenue earned and payable, from AbbVie.

Enanta has a solid financial base from milestone payments received and royalty revenues being earned on AbbVie s net sales of paritaprevir,

commented Jay R. Luly, Ph.D., President and Chief Executive Officer. We will use these revenues to sustain our business operations, and advance our wholly-owned, proprietary programs in HCV and NASH, among others.

Development Program and Business Review

Upcoming Events and Presentations

Conference Call and Webcast Information

a conference call and webcast today at 4:30 p.m. ET. To participate in the live conference call, please dial (855) 840-0595 in the U.S. or (518) 444-4814 for international callers. A replay of the conference call will be available starting

at approximately 6:30 p.m. Eastern time on August 6, 2015, through 11:59 p.m. Eastern time on August 12, 2015 by dialing (855) 859-2056 from the U.S. or (404) 537-3406 for international callers. The passcode for both the live

call and the replay is 82580357. A live audio webcast of the call and replay can be accessed by visiting the Calendar of Events section on the Investors page of Enanta s website at www.enanta.com.

Enanta Pharmaceuticals is a research and

development-focused biotechnology company that uses its robust chemistry-driven approach and drug discovery capabilities to create small molecule drugs for viral infections and liver diseases. Enanta has developed novel protease and NS5A inhibitors

that are members of the direct-acting-antiviral (DAA) inhibitor classes designed for use against the hepatitis C virus (HCV). Enanta s protease inhibitors partnered with AbbVie include paritaprevir, which is contained in AbbVie s marketed

DAA regimens for HCV. Enanta also has a program to develop a host-targeted antiviral (HTA) inhibitor class for HCV targeted against cyclophilin, as well as another DAA program to develop nucleotide polymerase inhibitors. In addition, Enanta has a

preclinical program in non-alcoholic steatohepatitis, or NASH, which is a condition that results in liver inflammation and liver damage caused by a buildup of fat in the liver.

Forward Looking Statements Disclaimer

contains forward-looking statements, including statements with respect to the prospects for regulatory approval in Japan for AbbVie s HCV treatment regimen containing paritaprevir, the prospects for AbbVie s development of a

next-generation regimen containing ABT-493, the prospects for advancement of the NASH development program, expectations for a commercialization regulatory approval milestone payment for Japan, the likely level of Enanta royalties on AbbVie s

future net sales of paritaprevir-containing regimens, and the projected sufficiency of Enanta s cash-equivalent resources and marketable securities. Statements that are not historical facts are based on

management s current expectations, estimates, forecasts and projections about Enanta s business and the industry in which it operates and management s beliefs and assumptions. The

statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is

expressed in such forward-looking statements. Important factors and risks that may affect actual results include: Enanta s revenues are dependent upon the success of AbbVie s planned regulatory approval and commercialization efforts for

its treatment regimens containing paritaprevir; Enanta s longer term revenues will likely be dependent upon the success of AbbVie s planned clinical development and commercialization of next-generation regimens containing ABT-493;

regulatory actions affecting further approvals of treatment regimens containing paritaprevir or any approval of a treatment regimen containing ABT-493; the pricing, market acceptance and reimbursement rates of treatment regimens containing

paritaprevir or ABT-493 compared to competitive HCV products on the market and product candidates of other companies under development; the discovery and development risks of early stage discovery efforts in new disease areas; potential competition

from the development efforts of others in those new disease areas; Enanta s lack of clinical development experience; Enanta s need to attract and retain senior management and key scientific personnel; Enanta s need to obtain and

maintain patent protection for its product candidates and avoid potential infringement of the intellectual property rights of others; and other risk factors described or referred to in Risk Factors in Enanta s most recent Form 10-K

for the fiscal year ended September 30, 2014 and other periodic reports filed more recently with the Securities and Exchange Commission. Enanta cautions investors not to place undue reliance on the forward-looking statements contained in this

release. These statements speak only as of the date of this release, and Enanta undertakes no obligation to update or revise these statements, except as may be required by law.

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