Aeterna Zentaris said today that it no longer expects to pursue regulatory approval for its Phase III candidate Zoptrex™ (zoptarelin doxorubicin) in endometrial cancer or any other indications, after the drug failed a Phase III clinical trial.

Zoptrex missed its primary endpoint in the ZoptEC study, which assessed the candidate in women with locally advanced, recurrent or metastatic endometrial cancer. Zoptrex failed to show a statistically significant overall survival increase compared to doxorubicin, Aeterna Zentaris acknowledged.

“The median overall survival period for patients treated with Zoptrex was 10.9 months compared to 10.8 months for patients treated with doxorubicin. This is not a statistically significant, clinically meaningful increase in overall survival,” Aeterna Zentaris CSO Richard Sachse, M.D., Ph.D., said in a statement. “The results of the study are not supportive to pursue regulatory approval.”

News of the failure set off a selloff of company stock among investors, sending the price of Aeterna Zentaris shares plunging 60%, to $1.30 as of 9:50 a.m.

Additionally, Zoptrex “generally performed no better than the comparator drug” on secondary efficacy endpoints for ZoptEC, as the median period of progression-free survival of the patients in the Zoptrex arm of the study was identical to that for patients in the doxorubicin arm, the company added.

There was also no meaningful difference between the Zoptrex and doxorubicin arms with respect to safety. The number of patients with cardiac disorders was similar: eight in the Zoptrex arm and nine in the doxorubicin arm, Arterna Zentaris said.

“Based on this outcome, we do not anticipate conducting clinical trials of Zoptrex  with respect to any other indications,” Aeterna Zentaris president and CEO David A. Dodd stated. “We are very disappointed with the outcome of the ZoptEC Phase III clinical study.”

Shifting Focus to Macrilen

Instead, Dodd said, the company has shifted its focus entirely to filing an NDA for its Phase III adult growth hormone deficiency (AGHD) candidate Macrilen™ (macimorelin), with a commercial launch planned “as soon as possible” upon approval.

“Our intention is to submit the Macrilen NDA in the third quarter of 2017 and, if the product receives FDA approval, to commercially launch the product in the first quarter of 2018,” Dodd said. “We continue to believe in the potential that Macrilen provides for us to become a focused specialty pharmaceutical company.”

Back on January 4, Aeterna Zentaris acknowledged that Macrilen did not achieve equivalence to the insulin tolerance test (ITT) as a means of diagnosing AGHD in a confirmatory Phase III clinical trial.

But on February 13, the company disclosed plans to pursue FDA approval for Macrilen, saying the ghrelin agonist “demonstrated performance supportive of achieving registration” having met the co-primary endpoint of “negative agreement” with the ITT, though not the other co-primary endpoint of “positive agreement” with the ITT.

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