Celldex Therapeutics, Inc. (CLDX) Monday said median overall survival and two-year survival data from a phase II trial of rindopepimut in patients with newly diagnosed brain cancer, EGFRvIII-positive glioblastoma or GB, were consistent with two previous smaller studies. The company plans to initiate a Phase III trial this year as stated earlier.
Rindopepimut has been granted Orphan Drug status by the U.S. FDA and the European Medicines Agency for treating GB, the most common and aggressive form of brain cancer.
The mature overall survival (OS) data for the multi-center, single arm, Phase 2 trial ACT III, showed a final median OS of 24.6 months from diagnosis. This was better than 15.2 months for a historical cohort of patients selected to match ACT III eligibility criteria.
Rindopepimut is an investigational immunotherapeutic vaccine that targets the tumor-specific oncogene, epidermal growth factor receptor variant III (EGFRvIII). Previously published retrospective analysis has documented that expression of the EGFRvIII oncogene correlates with poor long term survival. EGFR is only expressed in cancer cells and not in normal tissue.
The results from the Phase 2 clinical trial were very consistent with two previous smaller studies with rindopepimut in GB (ACTIVATE and ACT II) conducted at M.D. Anderson and Duke University which had showed 24.6 and 24.4 month median OS, respectively.
The two-year survival data in ACT III was was 52 percent, also consistent with the two prior studies, which had each showed 50 percent survival at two years. The result was 6 and 27 percent for the Matched historical control and Standard of care radiation/TMZ respectively.
Data from ACTIVATE and ACT II had also shown that about 20 percent of patients from each study continued treatment with durations of 6-8 years on study.
ACT III enrolled 65 patients with newly-diagnosed and optimally resected EGFRvIII-expressing GB. About 3 months post-diagnosis and following treatment with standard chemoradiation, patients started vaccination with rindopepimut in combination with standard of care (SoC) temozolomide therapy.
The result for the predefined primary endpoint in ACT III was 66 percent Progression Free Rate or "PFR" at approximately 8.5 months post-diagnosis. The predetermined estimate had been 53 percent, which was a high estimate derived from published results for standard chemoradiation with temozolomide (45%) and a cohort of patients with tumors expressing the EGFRvIII oncogene selected to match major ACT III eligibility criteria (29%).
The apparent PFS and OS benefits were seen in both temozolomide sensitive (MGMT methylated) patients as well as temozolomide resistant (MGMT unmethylated) patients.
CLDX is currently trading at $2.79, up $0.07 or 2.57%, on the Nasdaq. Over the past year, the stock traded in a range of $2.05 - $4.98.
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