Mpex Pharmaceuticals Presents New Data on MP-376 in Cystic Fibrosis

Details to be presented at NACFC and ICAAC/IDSA meetings this week

SAN DIEGO, Oct. 23 /PRNewswire/ -- Mpex Pharmaceuticals, Inc. today announced
additional clinical and preclinical results with MP-376, the company's novel
formulation of levofloxacin inhaled solution delivered by an Investigational
eFlow Nebulizer System for use in cystic fibrosis (CF) and chronic obstructive
pulmonary disease (COPD). Clinical results show that aerosol dosing of MP-376
was well tolerated at all dose levels tested after 14 days of dosing.
Encouraging signs of drug activity were also observed in this trial. New
preclinical results demonstrate that MP-376 has potent activity against
Pseudomonasaeruginosa (P. aeruginosa) infection under a wide array of
conditions, avoids resistance development when used at high concentrations
achievable with aerosol dosing and has anti-inflammatory properties in
pulmonary tissues in addition and unrelated to its antibacterial effects.
Detailed results are being presented at the North American Cystic Fibrosis
Conference (NACFC) and ICAAC/IDSA meetings taking place this week in Orlando,
Florida and Washington, D.C., respectively.

Clinical Results
The clinical results being presented at NACFC are from a Phase 1b safety,
tolerability and pharmacokinetic (PK) study performed in 40 CF patients with
stable disease at 11 U.S. clinical sites (Mpex 203). The study was a
placebo-controlled, dose escalation trial to analyze the effects of 14 days of
dosing at three different dose levels of MP-376 when administered by
inhalation using an Investigational eFlow Nebulizer System.

All patients were required to be culture positive for P. aeruginosa at
baseline. P. aeruginosa is a bacterial pathogen that is a leading cause of
morbidity in CF patients. The great majority of CF patients over the age of
18 are chronically infected with this pathogen and chronic infection has been
shown to lead to acute exacerbations and subsequent loss of lung function.

Results from this clinical trial indicated that MP-376 was well tolerated,
with no serious drug related adverse events reported. Dose escalation
proceeded successfully through the highest planned dose with no dose limiting
toxicities. PK results also met expectations, with sputum drug levels
increasing with increasing doses of inhaled MP-376.

Although this trial was not designed as an efficacy study, evidence of drug
activity was observed in this trial. Patients receiving MP-376 experienced a
reduction in P. aeruginosa counts well in excess of one log on average after
14 days of treatment, whereas counts in placebo treated patients increased
slightly over the treatment period. In addition, FEV1, a standard measure of
lung function, showed dose-related improvements in MP-376 treated patients,
with the highest dose group experiencing increases in FEV1 of greater than
15%.

"The results from this study are very encouraging," stated Dr. Jeff Loutit,
Chief Medical Officer of Mpex Pharmaceuticals. "The safety and PK results
were consistent with our expectations and support advancing the compound into
larger clinical trials. Furthermore, the effects seen on bacterial counts and
pulmonary function give us confidence as we move MP-376 through development.
This is particularly true given that the results were obtained in a patient
population that had significant prior inhaled antibiotic experience and many
patients were infected with multi-drug resistant P. aeruginosa."

Based on these results Mpex initiated a 28-day Phase 2 study in 140 CF
patients earlier this year at sites in the U.S., Germany and the Netherlands.
This study is expected to complete enrollment in the second quarter of 2009.
Results from this study, if successful, are expected to allow Mpex to choose
the optimal dosing regimen for Phase 3 clinical trials anticipated to begin
later in 2009.

Preclinical Results
MP-376 was designed to address many of the shortcomings of available inhaled
antibiotic formulations for CF patients. These shortcomings include the
following:
-- Low potency against P. aeruginosa
-- Lack of activity against other common CF pathogens
-- Potential for rapid resistance development
-- Suboptimal activity in biofilms, a factor that contributes to chronic
infections in CF patients
-- Reduced potency in anaerobic environments common in the CF lung from
thickened mucous layers
-- Reduced antibacterial activity in CF sputum
-- Inconvenient dosing regimens that reduce patient compliance

Preclinical results presented at the meetings this week show MP-376 offers
potentially substantial improvements in each of these areas:
-- Potency: MIC90s for MP-376 against nearly 300 P. aeruginosa clinical
isolates from CF patients were at least 4-fold lower than those
obtained
for tobramycin, amikacin and aztreonam.
-- Spectrum: MIC90s for MP-376 against clinical isolates for other
common
CF pathogens such as B. cepacia, S. maltophilia and A. xylosoxidans
were
substantially lower than for these other antibiotics. Previous in
vitro
work has also shown superior potency of MP-376 compared to other
agents
against gram positive bacteria commonly found in CF patients.
-- Resistance: in an in vitro model of resistance development in P.
aeruginosa, doses of levofloxacin formulated as MP-376 at levels
consistent with that which can be achieved with aerosol
administrations
demonstrated rapid bacterial killing with no development of resistance
over the course of 4 days. In contrast, doses of levofloxacin
mimicking
human exposures following systemic administration showed initial
bacterial killing, but allowed for resistance development within 24
hours. This demonstrates the importance of achieving high Cmax:MIC
ratios in pulmonary tissues to avoid resistance development in
bacteria.
-- Activity in biofilms: studies in an established in vitro biofilm
system
showed that levofloxacin potency was least affected compared to
tobramycin or aztreonam.
-- Activity in anaerobic environments: antimicrobial susceptibility in
more than 100 P. aeruginosa isolates from CF patients was compared
between aerobic and anaerobic testing conditions. The geometric mean
of
the MIC in levofloxacin treated isolates increased less than two fold
under anaerobic conditions, whereas tobramycin, amikacin and aztreonam
treated isolates increased 4-7 fold under anaerobic conditions. This
implies that MP-376 may retain its potency in anaerobic environments
in
the lung more effectively compared to other classes of antibiotics.
-- Activity in CF sputum: Studies of antibiotic activity in CF sputum
showed that levofloxacin retained its full antibacterial activity
against P. aeruginosa whereas tobramycin activity was decreased by 1-2
logs in the presence of CF sputum, consistent with previous studies.
-- Convenient dosing regimen: In an in vivo model of a chronic lung
infection due to P. aeruginosa, MP-376 showed comparable antibacterial
activity when administered once or twice per day. In contrast,
current
treatment options must be administered at least 2-3 times per day for
optimal activity.

In addition to these preclinical studies, Mpex is also presenting data at the
NACFC meeting indicating that MP-376 has anti-inflammatory activity that is
independent of its antibacterial effect. This was demonstrated in both in
vitro and in vivo models and includes effects on both IL-6 and IL-8, cytokines
which have both been implicated in destructive inflammatory processes in CF
lungs. These beneficial anti-inflammatory effects were not observed with
tobramycin or aztreonam.

"We believe that taken together these studies show a very attractive profile
for MP-376 in the treatment of chronic bacterial infections in CF patients,"
stated Dr. Michael Dudley, Senior VP of R&D and Chief Scientific Officer of
Mpex Pharmaceuticals. "MP-376 has the potential to address many of the
current shortcomings with inhaled antibiotic treatments in CF. The
combination of the inherent potency of levofloxacin and the novel formulation
we have developed for aerosol administration may allow us to achieve the
desired pharmacokinetic and pharmacodynamic parameters that are necessary for
long-term success in this indication. We look forward to working with CF
patients and caregivers to move this potentially important new treatment
option through development."

About MP-376
MP-376 is a proprietary formulation of levofloxacin that has been optimized
for aerosol delivery using a customized Investigational eFlow(R) Nebulizer
System (PARI Pharma, Munich, Germany). Levofloxacin is a fluoroquinolone
antibiotic that has been widely used in a variety of indications for over a
decade and has established safety and efficacy when administered orally or
intravenously against many bacterial pathogens, including P. aeruginosa.
Administration of MP-376 with a high efficiency nebulizer to the lungs allows
for the delivery of high concentrations of active drug directly to the site of
infection, while minimizing systemic exposure. Mpex believes this approach has
the potential to improve bacterial killing and reduce resistance development
versus traditional oral or IV routes of administration.

About Mpex Pharmaceuticals
Mpex Pharmaceuticals is a clinical stage biopharmaceutical company whose
mission is to develop important new therapies to combat the growing issue of
antibiotic resistance. The company's internal development pipeline focuses on
combining proprietary formulations, PK/PD strategies and novel potentiating
agents with proven antibiotics to overcome or directly inhibit the molecular
mechanisms in bacteria responsible for antibiotic resistance. Mpex's most
advanced product candidate, MP-376, is a proprietary aerosol formulation of
levofloxacin that is being developed clinically as a maintenance therapy for
the prevention of bacterial exacerbations in patients with cystic fibrosis and
COPD. The company has also built a discovery and development platform and
intellectual property estate around inhibitors of multi-drug resistant (MDR)
efflux pumps (EPIs) found in many gram-negative bacterial pathogens. Bacterial
efflux of antibiotics is a leading source of multi-drug resistance,
particularly in gram-negative organisms. Mpex compounds have been shown in
both in vitro and in vivo studies to overcome efflux-based resistance to
multiple classes of antibiotics. Mpex recently entered into a collaboration
with GlaxoSmithKline focused on developing multiple drug candidates utilizing
Mpex's EPI technology. Company website: www.mpexpharma.com.

SOURCE Mpex Pharmaceuticals, Inc.

Daniel Burgess, President & CEO of Mpex Pharmaceuticals, +1-858-875-6675; or
Jennifer Larson, +1-415-725-2017, jlarson@labfive.com, for Mpex
Pharmaceuticals