Paratek Presents Pre-Clinical Data on the Effects of Omadacycline on Clostridium Difficile

AMSTERDAM, Netherlands, April 11, 2016 (GLOBE NEWSWIRE) -- Paratek Pharmaceuticals, Inc. (Nasdaq:PRTK) today presented data from two pre-clinical studies evaluating the impact of omadacycline on gastrointestinal flora, including Clostridium difficile (C. difficile). A well-validated model showed that omadacycline, while extensively disrupting flora in the gastrointestinal tract, has a low propensity to induce C. difficile infection. A separate study found that omadacycline exhibited potent in vitro activity against C. difficile. The new data were presented at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Amsterdam. Paratek is a biopharmaceutical company focused on the development and commercialization of innovative therapies based upon tetracycline chemistry.

“Broad spectrum antibiotics have important therapeutic value, but they also have the potential to increase a patient’s risk for superinfection, such as C. difficile. When selecting antibiotic therapy, it’s important to consider this risk and take steps to minimize it,” said Evan Loh, President and Chief Medical Officer, Paratek. “Similar to other tetracyclines, it appears that the aminomethylcycline omadacycline, has a low potential risk of inducing C. difficile infection, suggesting that it may offer an advantage for patients who need treatment with a broad spectrum antibiotic in serious community-acquired infections where resistance is of concern.”

Antibiotic use is a well-known risk factor for C. difficile infection. Risk of infection has historically been low in patients treated with tetracyclines.1,2 Omadacycline is the first in a new generation of tetracyclines known as the aminomethylcyclines.

In vitro Study Results
The antimicrobial omadacycline was introduced to gut microbiota which were stable prior to exposure (Poster #P1324). Omadacycline was shown to disrupt microflora populations, with declines in populations of clostridia (~6 log10 cfu/mL), bifidobacteria (~6 log10 cfu/mL), B. fragilis group species (~3 log10 cfu/mL) Lactobaccilus spp. (~2 log10 cfu/mL) and Enterococcus spp. (~4 log10 cfu/mL) observed. Omadacycline did not disrupt the overall population of Enterobacteriaceae. Despite these changes, no evidence of C. difficile germination, vegetative cell proliferation or toxin production was observed, in contrast to other antimicrobials previously evaluated using this model.

To evaluate the microbiological activity of omadacycline in vitro and animal model testing was conducted (Poster #P1325). Omadacycline was tested in vitro against 27 clinical isolates of C. difficile using broth and agar microdilution methods. The MIC90 for omadacycline against C. difficile was 0.06 mg/L by broth dilution and 0.12 mg/L by agar dilution. Additional results showed omadacycline to be more active against C. difficile than doxycycline (MIC90 = 0.5 mg/L by broth and 1 mg/L by agar).

Using animal models to determine efficacy of omadacycline against C. difficile infection, hamsters were pretreated with clindamycin (10 mg/kg) 24 hours prior to infection. Post infection, hamsters were dosed orally with omadacycline (50/mg/kg/day), vancomycin (50 mg/kg/day) or vehicle (sterile water) for five days. The median survival for omadacycline-treated animals was 12 days compared to 2 days for vancomycin and 4 days for clindamycin pre-treatment.

About Clostridium Difficile (C. difficile)
Clostridium difficile (C. difficile) is a bacterium that causes life-threatening diarrhea. People who have other illnesses or conditions requiring prolonged use of antibiotics, and the elderly, are at greater risk of infection. Often, infections occur in hospitalized or recently hospitalized patients or nursing home residents. The U.S. Centers for Disease Control and Prevention (CDC) estimate that C. difficile causes almost 500,000 infections among U.S. patients in a single year. It is estimated to cause 14,000 deaths annually in the U.S. and costs at least $1 billion in medical fees.3

The bacterium is shed in feces. Any surface, device, or material that becomes contaminated with feces may serve as a reservoir for the C. difficile spores. C. difficile spores are transferred to patients mainly via the hands of healthcare personnel who have touched a contaminated surface or item. C. difficile can live for long periods on surfaces.4

In 2013, the CDC classified C. difficile infection as an urgent, drug-resistant threat to the U.S.5

About Paratek Pharmaceuticals, Inc.
Paratek Pharmaceuticals, Inc. is a biopharmaceutical company focused on the development and commercialization of innovative therapies based upon its expertise in novel tetracycline chemistry. Paratek's lead product candidate, omadacycline, is the first in a new class of tetracyclines known as aminomethylcyclines, with broad-spectrum activity against Gram-positive, Gram-negative and atypical bacteria. Paratek initiated a Phase 3 registration study in ABSSSI in June 2015 to determine the efficacy and safety of omadacycline compared to linezolid. The completion of enrollment in the ABSSSI trial was announced on April 4, 2016. Top-line data from this study is expected to be available as early as the end of June. A Phase 3 registration study for CABP comparing omadacycline to moxifloxacin was initiated in November 2015 and top line data is expected in the second half of 2017.

Omadacycline is a new once-daily oral and IV, well-tolerated broad-spectrum antibiotic being developed for use as empiric monotherapy for patients suffering from serious community-acquired bacterial infections, such as acute bacterial skin and skin structure infections, community acquired bacterial pneumonia, urinary tract infections (UTI), and other community-acquired bacterial infections, particularly when antibiotic resistance is of concern to prescribing physicians.

Paratek's second Phase 3 product candidate, sarecycline, is designed to be a well-tolerated, once daily, oral, narrow spectrum tetracycline-derived antibiotic with potent anti-inflammatory properties for the potential treatment of acne and rosacea in the community setting. Allergan owns the U.S. rights for the development and commercialization of sarecycline. Paratek retains all ex-U.S. rights. Allergan initiated two identical Phase 3 registration studies in December 2014 for sarecycline for the treatment of moderate to severe acne vulgaris.

For more information, visit www.paratekpharma.com.

Forward Looking Statement
Certain statements in this press release, including statements regarding the projected availability of top-line data from Paratek's Phase 3 clinical trials of omadacycline and the expected benefits of Paratek's product candidates are forward-looking statements. These forward-looking statements are based upon Paratek's current expectations and involve substantial risks and uncertainties. Paratek may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in these forward-looking statements and you should not place undue reliance on these forward-looking statements. Actual results and the timing of events could differ materially from those included in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks related to (i) unexpected results that may cause the designs of the clinical trials to change, or the projected timelines of the trials to be extended, (ii) unexpected decline in the rates of patient enrollment in the clinical trials, (iii) unforeseen adverse effects experienced by patients resulting in a clinical hold, (iv) failure of patients to complete clinical trials, (v) risks related to regulatory oversight of the trials, (vi) the need for substantial additional funding to complete the development and commercialization of product candidates and (vii) risks that data to date and trends may not be predictive of future results. These and other risk factors are discussed under "Risk Factors" and elsewhere in Paratek's Annual Report on Form 10-K for the year ended December 31, 2015 and Paratek's other filings with the Securities and Exchange Commission. Paratek expressly disclaims any obligation or undertaking to update or revise any forward-looking statements contained herein.

1 Baxter, R. et al “Antibiotic Use and Subsequent Clostridium Difficile Infection: A Case Control Study” ICAAC 2006; K-349.

2 Doernberg, SB. Et al “Does doxycycline protect against development of Clostridium difficile infection?” Clin Infect Dis. 2012 Sep;55(5):615-20. doi: 10.1093/cid/cis457. Epub 2012 May 4.

3 http://www.cdc.gov/drugresistance/threat-report-2013/pdf/ar-threats-2013-508.pdf#page=51

4 http://www.cdc.gov/hai/organisms/cdiff/Cdiff-patient.html

5 http://www.cdc.gov/drugresistance/biggest_threats.html

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Source:Paratek Pharmaceuticals