Positive results from Celldex Therapeutics' Phase 1 studies of CDX-1307 cancer vaccine candidate

Celldex Therapeutics, Inc. (NASDAQ: CLDX) today announced positive results from Phase 1 studies of CDX-1307 in patients with advanced epithelial cancers, including breast, colon, bladder and pancreatic cancer. CDX-1307, the first candidate from the Company’s Precision Targeted Immunotherapy Platform, utilizes monoclonal antibodies to deliver vaccine directly to the patient’s immune system and focuses the immune system against hCG beta (hCG-β), a cancer-associated target believed to play a role in more aggressive forms of the disease. The data, presented at the 24th Annual Meeting of the International Society for Biological Therapy of Cancer (iSBTc) in Washington, D.C., demonstrated enhanced immunological and biological responses and support the planned initiation of Phase 2 clinical trials in hCG-β expressing cancers.

The Phase 1 studies investigated the safety and immunogenicity of CDX-1307 alone and in combination with adjuvants, including GM-CSF and Toll-like Receptor (TLR) agonists (poly-ICLC or Hiltonol™ and R848 or resiquimod). The studies enrolled more than 80 patients with heavily pretreated, advanced-stage breast, colon, bladder and pancreatic cancer, with an average of 4.6 prior therapies across the treatment population. All patient cohorts demonstrated a favorable safety profile with no dose limiting toxicity to date. The combination of CDX-1307 with TLR agonists significantly enhanced immune responses against hCG-β, providing strong humoral responses in 88% of patients and cellular immune responses in 57% of patients analyzed to date. Immune responses occurred even in the presence of high circulating levels of hCG-β, suggesting that the CDX-1307 can overcome antigen tolerance in advanced and heavily pretreated cancers. Nine patients in the studies experienced disease stabilization from 2.3 months to 11.4 months following the initiation of CDX-1307 vaccination. Two of these patients have received multiple courses of CDX-1307 and continue treatment with stable disease at 6.4 and 11.4 months. These data provide the basis for advancing CDX-1307 into a front-line patient population selected for hCG-β expressing cancers. Celldex is planning the initiation of a Phase 2 study in patients with newly diagnosed bladder cancer in the first quarter of 2010.

“We have developed a CDX-1307 combination regimen that has shown promising results eliciting immunogenic and biologic responses in patients with advanced, difficult to treat and heavily pretreated cancers,” said Thomas Davis, M.D., Senior Vice President and Chief Medical Officer of Celldex Therapeutics. “Based on these findings, we will focus our efforts on CDX-1307 in earlier stage cancers where hCG-β appears to play an important role and where immunotherapy is likely to be even more effective, beginning with the initiation of a Phase 2 study in early-stage bladder cancer. Bladder cancer frequently expresses hCG-β and represents a clear unmet medical need—which we believe provides an excellent opportunity for CDX-1307.”