Synergy Pharmaceuticals Closes Callisto Deal

Synergy Pharmaceuticals Inc. has completed its acquisition of Callisto Pharmaceuticals Inc., the company announced Friday. Synergy is a biopharmaceutical company focused on new drugs to treat gastrointestinal disorders and diseases.

PRESS RELEASE
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.