(Reuters) - Celldex Therapeutics Inc said it would discontinue a late-stage study of its brain cancer vaccine after an independent interim analysis suggested the therapy might not show a statistically significant benefit in patient survival compared with standard chemotherapy.
Celldex shares more than halved to $3.76 in premarket trading on Monday.
The vaccine, Rintega, belongs to an emerging class of drugs that spur the immune system to recognize and attack cancer. It targets tumors with a genetic mutation found in about a third of all glioblastoma multiforme (GBM) cases. This amounts to roughly 4,000 patients in the United States.
There is no cure for GBM, the most common and deadliest form of brain cancer.
GBM tumors tend to become resistant to initial treatment relatively quickly. According to experts, the median survival rate for newly-diagnosed patients is about 14-15 months if they are given standard chemotherapy, such as Merck & Co’s Temodar.
After a preplanned interim analysis, an independent data safety and monitoring board estimated that the overall survival in patients with newly-diagnosed GBM who were given Rintega was at a par with those in the control group.
In the study, the overall survival of patients on Rintega was consistent with that seen in mid-stage studies. However, the survival of patients on standard chemotherapy was significantly higher than expected.
Celldex said it was abandoning the study on the board’s recommendation and it did not expect to incur substantial additional costs.
Data from a mid-stage trial of 73 patients had shown last year that adding the vaccine to standard therapy helped patients with a recurrent form of GBM live longer.
At the time, Celldex had sought to use the data to get accelerated approval for the vaccine, but the U.S. Food and Drug Administration had advised the company to wait for late-stage study data before filing a marketing application.
Celldex is unlikely to continue developing the vaccine, Wedbush Securities analyst David Nierengarten told Reuters.
In a note last month, Nierengarten had said the removal of Rintega sales would reduce his price target on the company’s stock to $7 from $24.
Celldex, which is also testing other compounds for different kinds of cancer, is still reviewing the interim analysis, company executives said on a conference call.
The vaccine, which has the FDA’s “breakthrough designation” for use in GBM, will still be given to patients if they choose it under a compassionate use program.
Reporting by Natalie Grover in Bengaluru; Editing by Kirti Pandey