Protagonist Announces Updated Phase 2 Data Presented at ASH Annual Meeting Supporting Long Term Efficacy of Hepcidin Mimetic PTG-300 in the Treatment of Polycythemia Vera

NEWARK, Calif., Dec. 6, 2020 /PRNewswire/ -- Protagonist Therapeutics, Inc. (Nasdaq:PTGX) today announced additional updated results from the ongoing Phase 2 study of PTG-300 in patients with polycythemia vera (PV), demonstrating dramatic decreases in the need for therapeutic phlebotomy in patients with PV, while maintaining control over blood hematocrit levels. The data were presented in an oral presentation today at the 62^nd American Academy of Hematology annual meeting, being held December 5-8, 2020.

"These results provide strong support for the potential for PTG-300 to improve on standards of care, not only for our patients receiving frequent phlebotomy but also for our patients who continue to receive phlebotomies in combination with other treatments," commented Andrew Kuykendall, M.D., study investigator and member of the Department of Malignant Hematology at the Moffitt Cancer Center. "Clinicians face significant challenges in appropriately managing hematocrit with current options, particularly in those patients who require frequent phlebotomies. The ability of PTG-300 to provide consistent, long term control of hematocrit and improve iron deficiency suggests that this approach could become an important treatment option for many patients across broad categories of patient populations."

Summary of Results

• Of the 18 PV patients treated with PTG-300, the vast majority were able to eliminate therapeutic phlebotomies and maintain a target hematocrit level of less than 45 percent.
• Treatment with PTG-300 was also shown to reverse iron deficiency, a serious side effect of regular therapeutic phlebotomies as a treatment for PV.
• Early observations suggest a decreased symptom burden over time, including overall burden (MPN-TSS), as well as measurements specific to mental function, fatigue and itching.
• Administration of PTG-300 was well tolerated, with injection site reactions and bruise as the only observed adverse events.

"We are very pleased with the study results obtained to date in controlling hematocrit with PTG-300, which mimics the mechanism of the natural hormone hepcidin in the body," commented Sam Saks, M.D., Chief Medical Officer of Protagonist. "We look forward to sharing these compelling data with U.S. and EU regulatory authorities in the first half of 2021 and to work toward alignment on the design of a pivotal trial in polycythemia vera. Complete enrollment of 50 patients in this Phase 2 study is expected in mid-2021."

The ongoing Phase 2 PTG-300 polycythemia vera study is designed to monitor the safety profile and obtain evidence of efficacy in approximately 50 patients requiring frequent phlebotomies (at least three phlebotomies in prior six months). The study design consists of three stages: a 16-week open-label stage with dose escalation, reduction, or maintenance every four weeks from 10 mg to 80 mg by subcutaneous administration at weekly intervals, a 12-week maintenance period at doses that generate desired hematocrit levels, and then a randomized and blinded withdrawal stage (1:1 treatment vs. placebo) for up to 12 weeks. The study also has an open-label extension for up to one year to monitor long-term safety and other effects. The primary endpoint is the control of hematocrit below 45 percent during the blinded randomized withdrawal period. Other endpoints of this clinical proof-of-concept study include measurement of blood parameters (hematocrit and hemoglobin levels), reductions or delay in phlebotomy requirements, and symptoms related to quality of life.

Additional information is available at https://clinicaltrials.gov/ct2/show/NCT04057040 and http://ptg300pvstudy.com/.

Conference Call and Webcast Information

Protagonist management will host a conference call at 8:30 a.m. EST on December 9, 2020, to provide a research update including Andrew Kuykendall, M.D., PTG-300 study investigator and member of the Department of Malignant Hematology at the Moffitt Cancer Center. To access the call, dial 1-844-515-9178 (U.S./Canada) or 1-614-999-9313 (international) and refer to conference ID number 8794865. A live and archived webcast will also be accessible in the Investors section of the Company's website at www.protagonist-inc.com.

About Protagonist Therapeutics, Inc.

Protagonist Therapeutics is a clinical stage biopharmaceutical company that utilizes a proprietary technology platform to discover and develop novel peptide-based therapeutics to address significant unmet medical needs and transform existing treatment paradigms for patients. PTG-300 is an injectable hepcidin mimetic in development for the treatment of polycythemia vera and other blood disorders. PTG-200 is an orally delivered, gut-restricted, interleukin-23 receptor specific antagonist peptide in development for the treatment of inflammatory bowel disease, with Crohn's disease as the initial indication. In addition to PTG-200, two oral peptide interleukin-23 receptor antagonist candidates from a collaboration with Janssen Biotech, Inc., are in development and have been selected for advancement into clinical studies. PN-943 is an orally delivered, gut-restricted alpha-4-beta-7 integrin specific antagonist peptide in development for the treatment of inflammatory bowel disease, with ulcerative colitis as the initial targeted indication.

Protagonist is headquartered in Newark, California. For further information, please visit www.protagonist-inc.com. 

Cautionary Note on Forward-Looking Statements

This press release contains forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include statements regarding our intentions or current expectations concerning, among other things, the potential of our product candidates to improve upon available therapies and our expectations regarding our interactions with regulatory authorities and the timing of the enrollment in our clinical trial.  In some cases, you can identify these statements by forward-looking words such as "anticipate," "believe," "may," "will," "expect," or the negative or plural of these words or similar expressions. Forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties that could cause actual results and events to differ materially from those anticipated, including, but not limited to, our ability to develop and commercialize our product candidates, our ability to earn milestone payments under our collaboration agreement with Janssen, the impact of the current COVID-19 pandemic on our discovery and development efforts, our ability to use and expand our programs to build a pipeline of product candidates, our ability to obtain and maintain regulatory approval of our product candidates, our ability to operate in a competitive industry and compete successfully against competitors that have greater resources than we do, and our ability to obtain and adequately protect intellectual property rights for our product candidates. Additional information concerning these and other risk factors affecting our business can be found in our periodic filings with the Securities and Exchange Commission, including under the heading "Risk Factors" contained in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2020, filed with the Securities and Exchange Commission. Forward-looking statements are not guarantees of future performance, and our actual results of operations, financial condition and liquidity, and the development of the industry in which we operate, may differ materially from the forward-looking statements contained in this press release.  Any forward-looking statements that we make in this press release speak only as of the date of this press release. We assume no obligation to update our forward-looking statements, whether as a result of new information, future events or otherwise, after the date of this press release.

SOURCE Protagonist Therapeutics, Inc.

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