Scalable Generation of Clinical-Grade Universal Human cDC1s Enables Potent Antitumor Immunotherapy

Despite decades of intensive clinical effort, monocyte-derived dendritic cell (DC) vaccines have not yet achieved sufficient clinical benefits in cancer therapy. Conventional type 1 DCs (cDC1s), a subset of antigen-presenting cells with superior cross-presentation capacity, are well established as pivotal mediators of antitumor immunity. However, their clinical translation has been hindered by the absence of scalable and efficient generation methods. Here, we develop a three-step strategy addressing this critical unmet need: a cost-effective, feeder cell-free, GMP-compatible approach enabling large-scale generation of cDC1s from human umbilical cord blood CD34+ hematopoietic stem and progenitor cells (CD34+ HSPCs). Starting from a single umbilical cord blood unit of CD34+ HSPCs, our method yields approximately 3.5x109 pure cDC1s--sufficient for over 700 therapeutic doses. These cDC1s exhibit robust antigen cross-presentation activity and substantial production of antitumor cytokines. Critically, in various humanized tumor mouse models, they elicit significantly stronger antitumor efficacy than either moDCs or PD-1 monoclonal antibody (mAb) alone, pronouncedly remodel the tumor microenvironment (TME), and synergize with PD-1 mAbs to achieve enhanced therapeutic effects. Furthermore, our system recapitulates the complete in vivo DC differentiation trajectory: from CD34+ HSPCs through early-pre-DCs and pre-DCs to mature subsets (cDC1s, cDC2s, DC3s, mregDCs, ASDCs). This platform thus provides a powerful tool to dissect the regulatory mechanisms governing human DC subset specification. Overall, this work overcomes a long-standing bottleneck in cDC1-directed cancer immunotherapy and accelerates the clinical translation of DC subset-selective immunotherapeutic strategies.