(Adds detail, shares)
July 1 (Reuters) - Agenus Inc said its experimental cancer vaccine helped brain tumor patients live nearly twice as long compared with those who received standard of care treatment.
The biotechnology company's shares jumped 23 percent to $3.96 before the bell.
The drug, when given in addition to standard treatment, extended median overall survival in 50 percent of newly-diagnosed glioblastoma multiforme (GBM) patients to two years in a mid-stage study.
GBM patients, who tend to succumb to the disease within one year, are usually treated with a combination of radiation and the chemotherapy drug temozolomide.
Patients on the vaccine also showed a median survival rate of nearly 18 months without the disease progressing, which is about two-three times longer than those on traditional therapy, Agenus said on Tuesday.
The company's Prophage vaccine is derived from the patient's own surgically removed tumor.
Agenus' lead experimental drug is being developed with partner GlaxoSmithKline Plc to treat malaria, melanoma and shingles. The company has also partnered with Pfizer Inc to test the drug, QS-21, for use in Alzheimer's disease.
The Lexington, Massachusetts-based company's stock closed at $3.22 on the Nasdaq on Monday. (Reporting by Natalie Grover in Bangalore; Editing by Joyjeet Das and Saumyadeb Chakrabarty)