Assembly Biosciences Announces Proposed Underwritten Offering of Common Stock INDIANAPOLIS

Biosciences Announces Proposed

Underwritten Offering of Common Stock

INDIANAPOLIS, Nov. 01, 2017 (GLOBE

NEWSWIRE) - Assembly Biosciences, Inc. (NASDAQ: ASMB) ("Assembly" or the "Company"), a clinical-stage

biotechnology company advancing a new class of oral therapeutic candidates for the treatment of hepatitis B virus (HBV) infection

and novel oral live biotherapeutic candidates, which are designed to treat disorders associated with the microbiome, today announced

that it intends to offer and sell, subject to market and other conditions, shares of its common stock in an underwritten public

offering. Assembly also intends to grant the underwriters a 30-day option to purchase up to an additional 15% of the shares of

common stock offered in the public offering. There can be no assurance as to whether or when the offering may be completed, or

as to the actual size or terms of the offering.

Jefferies LLC and William Blair & Company, L.L.C. are acting

as joint bookrunners for the offering.

The securities described above are being offered pursuant to

a shelf registration statement (File No. 333-208806), which was declared effective by the United States Securities and Exchange

Commission ("SEC") on January 19, 2016. All of the shares in the proposed offering are to be sold by Assembly.

This press release shall not constitute an offer to sell or

the solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any jurisdiction in which

such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any

such jurisdiction. The offering can be made only by means of a prospectus supplement and accompanying prospectus, copies of which

may be obtained at the SEC's website at www.sec.gov, or by contacting Jefferies LLC, Attention: Equity Syndicate Prospectus

Department, 520 Madison Avenue, 2nd Floor, New York, NY 10022, by telephone at (877) 547-6340, or by email at prospectus_department@jefferies.com;

or William Blair & Company, L.L.C., Attention: Prospectus Department, 150 North Riverside Plaza, Chicago, IL 60606, by telephone

at (800) 621-0687, or by email at prospectus@williamblair.com.

About Assembly Biosciences

Assembly Biosciences, Inc. is a clinical-stage public biotechnology

company developing two innovative platform programs: an HBV program advancing a new class of oral therapeutic candidates for the

treatment of hepatitis B virus (HBV) infection and a Microbiome program developing novel oral live biotherapeutic candidates, which

are designed to treat disorders associated with the microbiome. Assembly's HBV program is advancing multiple drug candidates with

the aim of increasing cure rates in patients with chronic HBV. The Company's Microbiome program consists of a fully integrated

platform that includes a robust strain identification and selection process, methods for strain isolation and growth under current

Good Manufacturing Practices and a patent-pending delivery system, GEMICEL , which is designed to allow for targeted oral delivery

of live biologic and conventional therapies to the lower gastrointestinal tract. Using its microbiome platform, the Company is

developing product candidates for various disease indications.

Forward-Looking Statements

The information in this press release contains forward-looking

statements regarding future events, including statements about Assembly's expectations regarding the offering's terms

or completion of the offering. Assembly intends such forward-looking statements to be covered by the safe harbor provisions

contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as

amended. Actual results or developments may differ materially from those projected or implied in these forward-looking statements.

Factors that may cause such a difference include, without limitation, risks and uncertainties related to market and other conditions,

the satisfaction of customary closing conditions related to the offering and the impact of general economic, industry or political

conditions in the United States or internationally. There can be no assurance that Assembly will be able to complete the offering

on the anticipated terms, or at all. More information about the risks and uncertainties faced by Assembly are more fully detailed

under the heading "Risk Factors" in Assembly's Annual Report on Form 10-K for the year ended December 31, 2016, and Quarterly

Report on Form 10-Q for the quarter ended June 30, 2017 filed with the Securities and Exchange Commission. You should not place

undue reliance on these forward-looking statements, which apply only as of the date of this press release. Except as required by

law, Assembly assumes no obligation to update publicly any forward-looking statements, whether as a result of new information,

future events or otherwise.