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ResTORbio’s Respiratory Drug Flunks Phase 3 Test, Shattering Shares

Xconomy Boston — 

A resTORbio respiratory drug has failed a late-stage test, and the company is stopping further development of the compound for lung infections in elderly patients.

In the first of two Phase 3 studies, resTORbio on Friday released preliminary data showing that its drug, RTB101, did not beat a placebo. Though the Boston-based company won’t proceed with the second Phase 3 study, it says it remains committed to developing the pill for other diseases of aging, including Parkinson’s.

Shares of resTORbio (NASDAQ: TORC) plunged more than 87 percent following the news.

ResTORbio is developing a class of drugs that block an enzyme called TORC1. The company has said this approach is meant to boost the immune system’s ability to fight infection, among other benefits. ResTORbio licensed the compound from Novartis (NYSE: NVS) in 2017.

RTB101 was tested in a Phase 3 study that enrolled more than 1,000 patients 65 or older. Patients were randomly assigned to receive the resTORbio drug or a placebo once daily for 16 weeks. The goal was to show a reduction in the percentage of patients with respiratory tract infections (RTI). According to data released Friday, the odds of experiencing such infections were 0.46 in the group that received RTB101—nearly the same as the 0.44 odds in the placebo group. The results were a stark contrast to Phase 2b data released last year, which showed that the percentage of patients with RTIs was reduced by more than 30 percent in patients treated with the drug.

Results on safety and secondary endpoints are not yet available. But resTORbio says it plans to do a deeper dive into the data to determine why the Phase 3 results differed so much from Phase 2.

In addition to the RTI study, the resTORbio drug is being tested in a Phase 1b/2a study in aging-related diseases, including Parkinson’s. That study is expected to report data in the middle of next year. But some analysts are already writing off RTB101’s prospects. In a research note Friday, SVB Leerink’s Geoffrey Porges said that the lack of evidence shown in the RTI study suggests development of the drug won’t be successful for other diseases.

“We regard the evidence of benefit in the new Parkinson’s indication as very marginal, and given the complex biology of this disease, and the lack of understanding of the disease process, find it hard to give the company any credit for this indication,” he wrote.

Anatomy of the lungs and heart image by Flickr user University of Liverpool Faculty of Health & Life Sciences via a Creative Commons license