Celtic Pharma Announces Preclinical Findings that XERECEPT(R) Potentiates Significantly the Tumor Inhibition Activity of Avastin(R)

NEW YORK, LONDON and BERMUDA, April 19, 2010 /PRNewswire/ — Celtic
Pharmaceutical Holdings L.P. (“Celtic Pharma”) today reported at the AACR
101st Annual Meeting 2010 in Washington, DC the results from several
preclinical studies of XERECEPT(R) in established models for breast, colon
and brain tumors. These animal studies were conducted at Duke University and
the Piedmont Research Center using solid human tumors including breast and
colon xenografts as well as both pediatric and adult human brain tumor
xenografts. All of these models demonstrated statistically significant tumor
regression and prolongation of survival following treatment with XERECEPT(R)
in combination with Avastin(R), compared to Avastin(R) alone. In the human
breast model both Avastin(R) and Xerecept(R) by themselves produced similar
antitumor effects, however, when Avastin(R) was combined with Xerecept(R),
antitumor effect was significantly increased (p<0.001). The enhanced
combination effect was statistically different (p<0.03) than either result
associated with the monotherapies. In the human colon xenograft model,
Xerecept was not active alone against this tumor model, while Avastin(R)
produced a significant tumor growth delay compared to the vehicle-treated
control. However, the combination therapy of Avastin(R) plus Xerecept(R)
significantly increased the overall survival of animals when compared to
treatment with vehicle (p<0.001) or bevacizumab alone (p<0.01). In the High
Grade Pediatric GBM model, Xerecept(R) had activity by itself, and the
combination of Xerecept(R) with bevacizumab was significantly better than
bevacizumab or Xerecept(R) alone. These preclinical findings demonstrate that
XERECEPT(R) has the ability to potentiate or provide a synergistic
enhancement of the antitumor effects of Avastin(R), in these various models.

“We have been seeing anecdotal observations from the Phase III trials of
Xerecept in brain tumor patients that this molecule may be doing more for
some of these patients than just controlling edema. Interestingly, we have 13
brain tumor patients still on daily Xerecept treatment from the 501 Phase III
open label study, with an average of 38 months (range 25 to 53 months) on
drug to date” commented Stephen Evans-Freke, Managing General Partner of
Celtic Pharma. “These new preclinical findings of synergistic activity of
Xerecept in combination with Avastin(R) in major tumor types may indicate a
broader role for this molecule than has been understood up to now”.

“From both a medial point of view and a commercial point of view, this
information could have profound implications and certainly merits further
investigation,” said John Mayo, Managing General Partner of Celtic Pharma.

“We are happy to have the opportunity to work with Celtic on this
potential new therapeutic combination for major solid tumor patient
populations,” commented Beth Hollister, Corporate Vice President, Charles
River Discovery and Imaging Services and Founder of Piedmont Research Center.
“We look forward to continuing to add to the scientific knowledge base for
this treatment as preparations are made for expanded clinical trials.”

XERECEPT(R) is an investigational new drug under development as a
steroid-sparing alternative to dexamethasone for patients with primary and
metastatic brain tumors. Dexamethasone is currently the standard treatment
for peritumoral brain edema, but is associated with debilitating side effects
including diabetes mellitus, hypertension, muscle weakness, bone loss,
impaired wound healing and opportunistic infections.

About Celtic Pharmaceutical Holdings L.P.

Celtic Pharmaceutical Holdings L.P. (Celtic Pharma) is a global private
equity investment firm focused on the biotechnology and pharmaceutical
industries. Celtic Pharma was founded by Stephen Evans-Freke and John Mayo,
CBE and is based in Bermuda, with offices in New York and London. Celtic
Pharma acquires and invests in late stage pharmaceutical programs and manages
these programs through their development to regulatory approval. Celtic
Pharma’s aim is to bridge the gap between the established pharmaceutical
companies’ new product pipeline crisis and the biotech industry’s capital
drought. For further information, please visit Celtic Pharma’s website at
http://www.celticpharma.com.

Forward-Looking Statements

Certain statements in this press release that are not historical facts,
including statements that are preceded by, or followed by, or that include
words such as “may,” “expect,” “anticipate,” “believe,” or “plan,” or similar
statements, are forward-looking statements that involve risks and
uncertainties, including risks relating to the results of the clinical trials
for XERECEPT(R) and the ability of Celtic Pharma to obtain regulatory
approval for XERECEPT(R). Actual results may differ materially from those
projected. These forward-looking statements represent our judgment as of the
date of the release. We disclaim, however, any intent to update these
forward-looking statements.

    Please Contact With Enquiries:

    Celtic Pharma
    Kathy Armstrong
    Investor Relations
    Tel: +1(212)616-4042
    kathy@celticpharma.com

    Media Contacts:

    FD
    US:
    Robert Stanislaro
    Tel: +1(212)850-5657
    Irma Gomez-Dib
    Tel: +1(212)850-5761

    UK:
    Jonathan Birt /John Dineen
    Tel: +44(0)20-7831-3113

SOURCE Celtic Pharmaceutical Holdings L.P.