Synergy Pharmaceuticals Announces Closing of Merger With Callisto Pharmaceuticals

Synergy Pharmaceuticals Announces Closing of Merger With Callisto
Pharmaceuticals

NEW YORK, Jan. 17, 2013 (GLOBE NEWSWIRE) -- Synergy Pharmaceuticals Inc.
(Nasdaq:SGYP), a developer of new drugs to treat gastrointestinal disorders
and diseases, today announced that its previously announced merger with
Callisto Pharmaceuticals, Inc. (formerly OTC QB: CLSP) closed effective today.

Under the terms of the merger agreement, as amended, each outstanding share of
Callisto common stock was converted into the right to receive 0.1799 of one
share of Synergy common stock and the approximately 22.3 million shares of
Synergy held by Callisto were canceled. Consequently, effective as of the
close of business today, Callisto's common stock will no longer be traded on
the OTC QB.

Each share of Synergy common stock received in connection with the merger will
be subject to a lock-up beginning January 17, 2013 and ending on the earlier
of (i) January 17, 2015, (ii) a Change in Control of Synergy (as defined in
the merger agreement), or (iii) written consent of Synergy, at Synergy's sole
discretion, provided that such consent shall apply to all shares issued
pursuant to the merger.

Philadelphia Stock Transfer, Inc., Synergy's transfer agent, will mail letters
of transmittal to all Callisto stockholders of record immediately prior to the
merger with instructions on how to deliver their stock certificates in
exchange for the merger consideration. Callisto stockholders should not
surrender their stock certificates until they have completed the letter of
transmittal. Callisto stockholders who held their shares in "street name"
through a bank or broker should contact their bank or broker to determine what
actions they must take to receive the merger consideration.

About Synergy

Synergy is a biopharmaceutical company focused on the development of new drugs
to treat gastrointestinal disorders and diseases. Synergy's lead proprietary
drug candidate plecanatide is a synthetic analog of the human gastrointestinal
hormone uroguanylin, and functions by activating the guanylate cyclase C
receptor on epithelial cells of the GI tract. Synergy completed a Phase I
study of plecanatide in healthy volunteers, a Phase IIa clinical trial in CIC
patients, and has recently completed a major Phase IIb/III clinical trial of
plecanatide to treat CIC. Plecanatide is also being developed to treat IBS-C,
with the first trial in IBS-C patients initiated in the fourth quarter of
2012. Synergy's second GC-C agonist SP-333 is in clinical development to treat
inflammatory bowel diseases, and has just completed its first Phase I trial in
healthy volunteers. More information is available at
http://www.synergypharma.com.

CONTACT: Investor Contact Information:
         Danielle Spangler
         The Trout Group
         synergy@troutgroup.com
         (646) 378-2924