The tumor microenvironment is a dynamic network of stromal, cancer and immune cells that interact and compete for resources. Mitochondria play an essential role in the control of metabolic plasticity and contribute to tumor progression and immune cell functionality. We previously identified the Vanin1 pathway as a tumor suppressor of sarcoma development via vitamin B5 and coenzyme A regeneration. Using an aggressive sarcoma cell line that lacks Vnn1 expression, we showed that administration of pantethine, a vitamin B5 precursor, impairs tumor growth in immunocompetent mice. Pantethine boosts anti-tumor type 1 immunity including polarization of myeloid and dendritic cells towards enhanced IFNγ-driven antigen presentation pathways and improved development of hypermetabolic effector CD8+ T cells endowed with potential anti-tumor activity. At later stages of treatment, the effect of pantethine is limited by the development of immune cell exhaustion. Nevertheless, its activity is comparable to that of anti-PD1 treatment in sensitive tumors. In humans, VNN1 expression correlates with improved survival and immune cell infiltration in soft tissue sarcomas but not osteosarcomas. Pantethine could be a potential therapeutic immunoadjuvant for the development of anti-tumor immunity.

Chordomas are rare, slow-growing tumors of the axial skeleton. These tumors are locally aggressive and refractory to conventional therapies. Radical surgery and radiation remain the first-line treatments. Despite these aggressive treatments, chordomas often recur and second-line treatment options are limited. The mechanisms underlying chordoma radioresistance remain unknown, although several radioresistant cancer cells have been shown to respond favorably to aldehyde dehydrogenase (ALDH) inhibition. The study of chordoma has been delayed by small patient cohorts and few available models due to the scarcity of these tumors. We thus created cellular 3D models of chordoma by using low-adherence culture systems. Then, we evaluated their radiosensitivity using colony-forming and spheroid size assays. Finally, we determined whether pharmacologically inhibiting ALDH increased their radiosensitivity. We found that 3D cellular models of chordoma (derived from primary, relapse, and metastatic tumors) reproduce the histological and gene expression features of the disease. The metastatic, relapse, and primary spheroids displayed high, medium, and low radioresistance, respectively. Moreover, inhibiting ALDH decreased the radioresistance in all three models.

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