CD40 Agonist, Flt3 Ligand, and Chemotherapy in HER2 Negative Breast Cancer

The immunotherapy drugs CDX-301 and CDX-1140 in combination with the standard chemotherapy treatment PLD work by kickstarting the immune response against cancer cells. CDX-301 increases the antigen presenting immune cells needed to kickstart the immune response, CDX-1140 activates these cells, and chemotherapy helps release antigens from the cancer cells to train these antigen presenting immune cells to recognize the cancer for the immune system to attack it. Metastatic or unresectable triple negative breast cancer patients will receive this triplet combination that has been shown in preclinical studies to be more effective than the individual treatments or doublet combinations. To understand how the immunotherapies are working, some patients will receive the immunotherapy or chemotherapy only for one cycle prior to receiving the full triplet combination therapy. Ultimately, all patients will receive the triplet combination to study safety and how effective this treatment is at controlling triple negative breast cancer and improving survival outcomes. The original design of the project includes 3 cohorts (arms). In February 2024 Cohort B (experimental arm) was closed to further enrollment. Cohort B includes the following design: PLD chemotherapy will be administered 40 mg/m2 as intravenous injection once per cycle starting on cycle 2 until toxicity or progression. CDX-1140 will be administered 1.5mg/kg as intravenous injection once per cycle until toxicity or progression for up to 24 months. CDX-301 will be administered 75µg/kg as subcutaneous injection daily x 5 days cycles 1 and 2 only.