Protagonist Craters After Discontinuing Phase IIb Ulcerative Colitis Study

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Shares of Protagonist Therapeutics, Inc. plunged more than 60 percent in pre-market trading after the company announced it will discontinue its Phase IIb ulcerative colitis treatment after a review from an Independent Data Monitoring Committee (DMC).

Following a review of the first 65 patients who completed a 12-week treatment with its investigational drug PTG-100, the DMC deemed the trial to be futile based on an analysis of the primary endpoint of clinical remission, Protagonist announced this morning. The Phase IIb trial, PROPEL, was testing the efficacy of the PTG-100, an investigational oral GI-restricted alpha-4-beta-7 integrin antagonist peptide. The company said it will examine the data from the Phase IIb trial before making any decision regarding the future of PTG-100. No safety concerns were noted in the DMC analysis, the company said.

Newark, Calif.-based Protagonist announced its plans to discontinue the study this morning and investors ran for the hills. Prices plunged as low as $7.87 per share. Protagonist closed on Friday at $20.43 per share. Protagonist said it was notified of the DMC’s recommendation following the closing of the market on Friday.  

The company said it will notify trial investigators that “randomization of potential participants and further treatment of patients currently in the study will be discontinued.” Additionally, Protagonist said it will postpone its decision about the initiation of a Phase II/III clinical trial of PTG-100 in chronic pouchitis until there has been a full review of the interim data from the ulcerative colitis study.

Dinesh V. Patel, president and chief executive officer of the Bay Area company, said they were disappointed in the futility-based outcome, which he said was also accompanied by an unexpectedly high placebo rate.

“We are very grateful to the patients and investigators who participated in the PROPEL trial. Protagonist remains committed to progressing its other peptide-based assets currently in clinical development, PTG-200 and PTG-300, and to discovering new peptide-based therapeutic entities to address significant unmet medical needs,” Patel said in a statement.

Although the PTG-100 treatment failed Protagonist has a few other therapies in its pipeline that could prove to be strong drivers if approved. Last year Protagonist received a nearly $1 billion vote of confidence from Johnson & Johnson subsidiary Janssen Pharmaceuticals,  to develop PTG-200, Protagonist's first-in-class, oral peptide Interleukin-23 receptor antagonist. A Phase I trial began in the fall of 2017 and results are expected later this year. At the time the deal was announced Protagonist said PTG-200 has the potential to become a transformative treatment in IBD. The company said the oral drug is designed to offer significant advantages over injectable antibody drugs, including improved convenience, patient compliance and the potential for improved safety and tolerability compared to currently approved injectable antibody drugs.

Earlier this month the FDA awarded Orphan Drug designation to Protagonists’ beta-thalassemia treatment PTG-300. Protagonist expects to initiate a global clinical trial of PTG-300 in patients with beta-thalassemia this year.

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