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Hampton-based Celldex Presents Clincal Data of CDX-301 in Allogeneic Hematopoietic Stem Cell Harvest

Hampton-based Celldex Therapeutics, Inc. recently presented new clinical data on CDX-301 (recombinant human Flt3 ligand), a potent hematopoietic cytokine that uniquely expands dendritic cells and hematopoietic stem cells. An open label, pilot study of CDX-301, alone and in combination with Mozobil (plerixafor), in sibling-matched donors for allogeneic hematopoietic stem cell transplantation (HSCT) recipients who have certain hematologic malignancies is currently enrolling donor/patient pairs. Early data were presented in a poster entitled “Preliminary Safety and Efficacy Data using CDX-301 (Flt3 ligand) as a Sole Agent to Mobilize Hematopoietic Cells Prior to HLA-matched Sibling Donor Transplantation” at the 2016 BMT Tandem Meeting, the annual meeting of the American Society for Blood and Marrow Transplantation (ASBMT).

Three donor/patient pairs showed that CDX-301 given as a single agent for 5 days was well tolerated and effective at mobilizing hematopoietic stem cells in healthy donors. The stem cell graft contained notable increases in naïve lymphocytes and plasmacytoid dendritic cells compared to administration of G-CSF (granulocyte colony-stimulating factor) and is consistent with preclinical data suggesting a possible better outcome for recipients. Notably, no donors required rescue with either G-CSF or Mozobil in this arm of the study, and none experienced any grade 3 or 4 adverse events. Recipients experienced successful engraftment in an expected time frame. Additional donor/patient pairs are being accrued to a second, planned cohort in order to assess the potential synergies and feasibility of combining CDX-301 with Mozobil in this setting.

“From these data and preclinical studies, CDX-301 appears to be an effective, targeted approach to mobilization comparable to G-CSF. With a relatively short course of treatment, we are observing specificity for mobilized stem cells and a lack of toxicity, instead of broad cellular mobilization and side effects,” said Steven Devine, M.D., Professor of Internal Medicine, Division of Hematology, Department of Internal Medicine, and Program Director, Blood and Marrow Transplant Program at The Ohio State Comprehensive Cancer Center.

“CDX-301 shows a favorable safety profile and effectively mobilizes early stem cells when used alone, and we expect even greater yields in the next cohort where we combine with Mozobil,” said Thomas Davis, M.D., Executive Vice President and Chief Medical Officer of Celldex Therapeutics. “CDX-301 could potentially provide good engraftment, less graft-versus-host disease and mitigated side effects, which would be a breakthrough for these patients undergoing HSCT. We are also looking forward to receiving data from investigators who are using CDX-301 in other drug combination studies designed to assess its potential in immunotherapy for cancer and other indications.”

In addition, CDX-301 has shown impressive results in models of cancer, infectious diseases, inflammatory/autoimmune diseases and immune suppression. Celldex believes CDX-301 may hold significant opportunity for synergistic development in combination with other proprietary molecules in the Company’s portfolio and in external development. CDX-301 is in clinical development for cancers in combination with vaccines, adjuvants, and other treatments that result in release of tumor antigens to enhance tumor immunogenicity.

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