Shares of the Vienna, Va., company were down nearly 48% to $13.26 at last check. Trading was halted at least three times, according to Bloomberg.
CEL-SCI said that the Phase 3 study for its immunotherapy Multikine indicated a significant overall survival benefit for patients who received the treatment regimen followed by surgery and radiotherapy, but not for patients who had chemotherapy added to the same treatment.
Patients treated with the Multikine treatment regimen plus standard of care compared with standard of care alone had an overall survival benefit of 14.1% at 5 years which exceeded the pre-defined 10% overall survival benefit set out for the study population as a whole.
When the complete study population to which the Multikine
treatment regimen was administered and higher risk was compared to control, the study did not achieve its primary endpoint of a 10% improvement in overall survival.
The overall suvrival benefit of 14.1% at five years for the lower risk subgroup exceeded the 10% overall survival benefit set out for the study population as a whole.
The chemotherapy, cisplatin, was given intravenously and may have negated the survival benefit imparted by Multikine immunotherapy in these patients, the company said.
The global trial enrolled 928 stage III and IVa patients through 78 sites on three continents.
No safety issues for Multikine were found during or as a result of its administration, including no late effects, in the overall treated patient population, the company said.
"Based on this landmark study data, we intend to seek FDA approval for what could become the first treatment in newly diagnosed advanced primary head and neck cancer in many decades," CEO Geert Kersten said in a statement.