(Reuters) - Peregrine Pharmaceuticals Inc reported revised results from a mid-stage lung cancer study of its experimental drug bavituximab that appeared to be not as good as the data it originally posted in early September.
The company's shares, which were up in premarket trade on Tuesday, fell as much as 10 percent on open on the Nasdaq. They later recouped their losses to trade flat around midday.
"I think what may be contributing to the (share fall) is that the difference in overall survival is not statistically significant," McNicoll, Lewis & Vlak analyst George Zavoico said in an email.
The study was, however, for dose confirmation purposes and was never intended to show a statistically significant difference in median overall survival, Zavoico said.
Revised data from the 121-patient study showed that patients survived for a median of 11.7 months when given bavituximab along with chemotherapy, compared with 7.3 months for a control arm that consisted of patients on chemotherapy alone or chemotherapy along with a low dose of the drug.
Tuesday's reworked analysis comes about five months after Peregrine said that the data it initially reported from the same study contained major discrepancies.
Peregrine, which was testing 1mg/kg and 3mg/kg doses of bavituximab, said in January that the discrepancies were found to be isolated to the placebo and the 1mg/kg treatment arms.
The company said it considered the 1mg/kg treatment arm as part of the placebo, or control arm, in the revised analysis to try and remove any potential bias accruing to the treatment group receiving the 3mg/kg dose.
Peregrine said it was preparing to discuss further development of the drug with the U.S. Food and Drug Administration in a meeting by mid-year and aims to be in a position to begin a pivotal study on the drug near year-end.
"Partnering interest remains high and the updates from this trial should help advance these discussions," Peregrine Chief Executive Steven King said in a statement.
Analyst Zavoico said he treats Tuesday's news as an opportunity to buy Peregrine stock.
Peregrine's stock jumped nearly 50 percent to $4.50 in early September, following its announcement that bavituximab along with chemotherapy doubled the survival time of lung cancer patients.
The shares have, however, since lost about 64 percent of their value to their Friday close.
Bavituximab is one of Tustin, California-based Peregrine's most important and advanced products. It is also being tested to treat breast cancer, pancreatic cancer and hepatitis C.
(Reporting by Zeba Siddiqui in Bangalore; Editing by Sriraj Kalluvila)