New Non-Clinical Data Confirm SparVax® Anthrax Vaccine Can Provide Protection Against Lethal Anthrax Challenge

New Non-Clinical Data Confirm SparVax® Anthrax Vaccine Can Provide Protection
                       Against Lethal Anthrax Challenge

PR Newswire

ANNAPOLIS, Md., Sept. 13, 2013

ANNAPOLIS, Md., Sept. 13, 2013 /PRNewswire/ -- PharmAthene, Inc. (NYSE MKT:
PIP) announced today that new non-clinical animal data from the Company's
SparVax^® next-generation anthrax vaccine program were presented at the 53^rd
Annual Interscience Conference on Antimicrobial Agents and Chemotherapy
(ICAAC) in Denver, Co. The data presented showed that immunization with
SparVax^® provides dose-dependent protection against lethal anthrax infection.

Dr. Sherry Crowe, Director, Immunology at PharmAthene, discussed the results
in an oral presentation entitled, "Recombinant Protective Antigen Vaccine
(SparVax^®) Provides Protection against Lethal Challenge with Bacillus
anthracis in New Zealand White Rabbits."

Summary of SparVax^® Findings Reported

The need for newer anthrax vaccines based on modern vaccine technology, which
offer the potential for improved safety, convenience and cost-effectiveness,
is widely acknowledged. SparVax^® is a next-generation anthrax vaccine based
on recombinant protective antigen (rPA), the principal virulence factor of the
organism, B. anthracis. It is being developed for pre- and post-exposure
protection against anthrax.

Previous non-clinical animal studies have demonstrated that immunization with
SparVax^® stimulates the production of anti-PA antibodies that provide
protection against anthrax infection. The objective of the current study was
to provide further confirmation of the immunogenicity and efficacy of
SparVax^® (manufactured in the U.S.) and determine the optimal dose range for
protection.

In the current study, New Zealand White rabbits were administered escalating
doses of SparVax^® ranging from 0.003micrograms to 1.0micrograms of rPA.
Control animals received either no immunization or were administered saline.
Following immunization, the animals were challenged with B. anthracis spores
(Ames strain).

The results demonstrated that SparVax^® was effective in providing protection
against lethal inhalation anthrax challenge and resulted in no adverse
clinical observations. In the study, immunization with SparVax^® stimulated a
dose-dependent antibody response, which correlated with survival.

"PharmAthene is pleased to be working in partnership with the Biomedical
Advanced Research and Development Authority (BARDA) towards our mutual goal of
advancing novel, next-generation anthrax vaccines to address important
national security initiatives," said Eric I. Richman, President and Chief
Executive Officer. "We look forward to continuing this progress and
commencing a Phase 2 clinical trial of SparVax^® later this year."

Important Additional Information about the Proposed Merger

On August 1, 2013, PharmAthene filed with U.S. Securities and Exchange
Commission (the "SEC") a current report on Form 8-K, which includes a copy of
a merger agreement and related documents relating to a proposed merger
involving Theraclone Sciences, Inc. ("Theraclone") and PharmAthene. On
September 9, 2013, PharmAthene filed a registration statement on Form S-4 with
the SEC, which contains a preliminary proxy statement/prospectus/consent
solicitation and other relevant materials, and plans to file with the SEC
other documents regarding the proposed transaction. Once the registration
statement has been declared effective, the final joint proxy statement /
prospectus / consent solicitation will be sent to the stockholders of
PharmAthene and Theraclone in connection with the stockholder votes on matters
relating to the proposed transaction. The proxy statement/prospectus/consent
solicitation contains information about PharmAthene, Theraclone, the proposed
transaction, and related matters.

STOCKHOLDERS ARE URGED TO READ THE PROXY STATEMENT / PROSPECTUS / CONSENT
SOLICITATION (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS THERETO) AND OTHER
DOCUMENTS FILED WITH THE SEC CAREFULLY IN THEIR ENTIRETY AS THEY BECOME
AVAILABLE, BECAUSE THEY CONTAIN OR WILL CONTAIN, AS THE CASE MAY BE, IMPORTANT
INFORMATION THAT STOCKHOLDERS SHOULD CONSIDER BEFORE MAKING A DECISION ABOUT
THE MERGER AND RELATED MATTERS. In addition to receiving the proxy
statement/prospectus/consent solicitation and proxy card by mail, stockholders
will also be able to obtain the proxy statement/prospectus/consent
solicitation, as well as other filings containing information about
PharmAthene, without charge, from the SEC's website (http://www.sec.gov) or,
without charge, by contacting Stacey Jurchison at PharmAthene at (410)
269-2610.

No Offer or Solicitation

This communication is not intended to and does not constitute an offer to sell
or the solicitation of an offer to subscribe for or buy or an invitation to
purchase or subscribe for any securities or the solicitation of any vote or
approval in any jurisdiction in connection with the merger or otherwise, nor
shall there be any sale, issuance or transfer of securities in any
jurisdiction in contravention of applicable law. No offer of securities shall
be made except by means of a prospectus meeting the requirements of Section 10
of the Securities Act of 1933, as amended.

Participants in Solicitation

PharmAthene and its executive officers and directors may be deemed to be
participants in the solicitation of proxies from PharmAthene's stockholders
with respect to the matters relating to the proposed merger. Theraclone may
also be deemed a participant in such solicitation. Information regarding
PharmAthene's executive officers and directors is available in Amendment No. 1
to PharmAthene's proxy statement on Schedule 14A, filed with the SEC on May 9,
2013. Information regarding such executive officers and directors and
regarding any interest that PharmAthene, Theraclone or any of the executive
officers or directors of PharmAthene or Theraclone may have in the transaction
will be set forth in the final proxy statement/prospectus/consent solicitation
that PharmAthene will file with the SEC in connection with its stockholder
vote on matters relating to the proposed transaction. Stockholders will be
able to obtain this information by reading the final proxy
statement/prospectus/consent solicitation when it becomes available.

About PharmAthene

PharmAthene is a leading biodefense company engaged in the development and
commercialization of next generation medical countermeasures against
biological and chemical threats. PharmAthene's current biodefense portfolio
includes the following product candidates:

  oSparVax^® - a next generation recombinant protective antigen (rPA) anthrax
    vaccine
  orBChE bioscavenger - a medical countermeasure for nerve agent poisoning by
    organophosphorous compounds, including nerve gases and pesticides
  oValortim^® - a fully human monoclonal antibody for the prevention and
    treatment of anthrax infection

In addition, in May 2013, the Delaware Supreme Court issued its ruling on the
appeal in our litigation with SIGA Technologies, affirming the Court of
Chancery's finding that SIGA was liable for breach of contract, reversing its
finding of promissory estoppel, and remanding the case back to the Court of
Chancery to reconsider the appropriate remedy and award of attorney's fees and
expert witness costs in light of the Supreme Court's opinion. For more
information about PharmAthene, please visit www.PharmAthene.com.

About Theraclone

Theraclone is a biopharmaceutical company focused on the discovery and
development of novel, monoclonal antibody therapeutics for diseases that are
devastating for patients and their families and which are a significant threat
to human health. Theraclone leverages its proprietary antibody discovery
technology, I‑STAR (In‑Situ Therapeutic Antibody Rescue), to identify rare
human antibodies that may be developed into antibody product candidates that
are potentially safer and more effective than current therapies. Theraclone
has a portfolio of innovative antibodies in clinical and preclinical
development targeting serious medical conditions with a significant unmet
medical need and a primary focus on infectious disease and cancer, which
include:

  oTCN-032 - a recombinant fully human monoclonal antibody for the treatment
    of patients hospitalized with serious influenza
  oTCN-202 - a recombinant fully human monoclonal antibody for the treatment
    and prevention of cytomegalovirus, or CMV infections

For more information about Theraclone, please visit
www.theraclone-sciences.com. 

Forward-Looking Statement Disclaimer

Except for the historical information presented herein, matters discussed may
constitute forward-looking statements within the meaning of the Private
Securities Litigation Reform Act of 1995 that are subject to certain risks and
uncertainties that could cause actual results to differ materially from any
future results, performance or achievements expressed or implied by such
statements. Statements that are not historical facts, including statements
preceded by, followed by, or that include the words "will"; "potential";
"believe"; "anticipate"; "intend"; "plan"; "expect"; "estimate"; "could";
"may"; "should"; or similar statements are forward-looking statements. Such
statements include, but are not limited to those referring to the potential
for the generation of value, ability to leverage funding sources, potential
for revenue, and potential for growth. PharmAthene disclaims any intent or
obligation to update these forward-looking statements. Risks and
uncertainties include, among others, failure to obtain necessary shareholder
approval for the proposed merger with Theraclone and the matters related
thereto; failure of either party to meet the conditions to closing of the
transaction; delays in completing the transaction and the risk that the
transaction may not be completed at all; failure to realize the anticipated
benefits from the transaction or delay in realization thereof; the businesses
of PharmAthene and Theraclone may not be combined successfully, or such
combination may take longer, be more difficult, time-consuming or costly to
accomplish than expected; operating costs and business disruption during the
pendency of and following the transaction, including adverse effects on
employee retention and on business relationships with third parties; the
combined company's need for and ability to obtain additional financing; risk
associated with the reliability of the results of the studies relating to
human safety and possible adverse effects resulting from the administration of
the combined company's product candidates; unexpected funding delays and/or
reductions or elimination of U.S. government funding for one or more of the
combined company's development programs; the award of government contracts to
competitors; unforeseen safety issues; unexpected determinations that these
product candidates prove not to be effective and/or capable of being marketed
as products; as well as risks detailed from time to time in PharmAthene's Form
10-K and quarterly reports on Form 10-Q under the caption "Risk Factors" and
in its other reports filed with the SEC. In particular, there is significant
uncertainty regarding the level and timing of sales of Arestvyr™ and when and
whether it will be approved by the U.S. FDA and corresponding health agencies
around the world. PharmAthene cannot predict with certainty if or when SIGA
will begin recognizing profit on the sale thereof and there can be no
assurance that any profits received by SIGA will be significant. In its May
2013 decision, the Delaware Supreme Court reversed the remedy ordered by the
Court of Chancery and remanded the issue of a remedy back to the trial court
for reconsideration in light of the Supreme Court's opinion. As a result,
there can be no assurance that the Chancery Court will issue a remedy that
provides PharmAthene with a financial interest in Arestvyr™and related
products or any remedy. In addition, significant additional research work,
non-clinical animal studies, clinical trials, and manufacturing development
work remain to be done with respect to all of PharmAthene's product
candidates. At this point there can be no assurance that any of these product
candidates will be shown to be safe and effective and approved by regulatory
authorities for use in humans. Copies of PharmAthene's public disclosure
filings are available from its investor relations department and its website
under the investor relations tab at http://www.pharmathene.com. 

SOURCE PharmAthene, Inc.

Website: http://www.pharmathene.com
Contact: Stacey Jurchison, PharmAthene, Inc., (410) 269-2610,
Stacey.Jurchison@PharmAthene.com