Tokai Pharmaceuticals said it will end enrollment in its ongoing Phase II ARMOR2 expansion trial studying galeterone in metastatic castration-resistant prostate cancer (mCRPC) patients who are resistant to enzalutamide.

In a regulatory filing yesterday, Tokai also said it will not go ahead with a planned study of galeterone in mCRPC patients who rapidly progress on either enzalutamide, which is marketed as Xtandi® by Medivation—whose planned $14 billion acquisition by Pfizer was announced yesterday—or abiraterone acetate, which is marketed as Zytiga® by Johnson & Johnson’s Janssen Biotech.

The clinical setbacks are the second and third reported by Tokai for galeterone in less than a month.

On July 26, the company said it was ending its Phase III ARMOR3-SV trial comparing galeterone to enzalutamide in treatment-naïve mCRPC patients whose prostate tumors express the AR-V7 splice variant, at the recommendation of the trial’s independent Data Monitoring Committee.

The committee concluded that ARMOR3-SV would not meet its primary endpoint of showing improved radiographic progression-free survival for galeterone versus enzalutamide.

“Tokai is continuing to evaluate the unblinded data from its recently discontinued ARMOR3 clinical trial,” the company said yesterday, adding that it “is assessing potential next steps in its galeterone program.”

Three days after announcing the failure of SRMOR3-SV, Tokai said it was eliminating about 60% of its workforce, shrinking its staff to 10 full-time equivalent employees by the end of the third quarter. The company said it expected the job cuts to generate approximately $4.2 million in reduced annualized operating expenses, following a third-quarter charge of approximately $1.3 million.

“This workforce reduction is designed to reduce operating expenses while the company conducts a comprehensive evaluation of strategic options for galeterone and its pipeline.”

Galeterone is an oral small molecule designed to work by using the pathways of current therapies, such as enzalutamide and abiraterone, as well as through androgen receptor degradation intended to decrease their sensitivity to androgen activity and thus reduce tumor growth.

Tokai has worldwide development and commercialization rights to galeterone, which is indicated for mCRPC patients.

News of the latest clinical setbacks sent the price of Tokai shares slipping nearly 18% from yesterday’s closing price of $1.36 to $1.12 as of 9:01 a.m.

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