Reactive oxygen species (ROS) are produced by every aerobic cell during mitochondrial oxidative metabolism as well as in cellular response to xenobiotics, cytokines, and bacterial invasion. Superoxide Dismutases (SOD) are antioxidant proteins that convert superoxide anions (O₂^•−) to hydrogen peroxide (H₂O₂) and dioxygen. Using the differential in the level of oxidative stress between normal and cancer cells, SOD mimetics can show an antitumoral effect and prevent oxaliplatin-induced peripheral neuropathy. New Pt(IV) conjugate prodrugs (OxPt-x-Mn1C1A (x = 1, 1-OH, 2)), combining oxaliplatin and a Mn SOD mimic (MnSODm Mn1C1A) with a covalent link, were designed. Their stability in buffer and in the presence of sodium ascorbate was studied. In vitro, their antitumoral activity was assessed by the viability and ROS production of tumor cell lines (CT16, HCT 116, KC) and fibroblasts (primary culture and NIH 3T3). In vivo, a murine model of colorectal cancer was created with subcutaneous injection of CT26 cells in Balb/c mice. Tumor size and volume were measured weekly in four groups: vehicle, oxaliplatin, and oxaliplatin associated with MnSODm Mn1C1A and the bis-conjugate OxPt-2-Mn1C1A. Oxaliplatin-induced peripheral neuropathy (OIPN) was assessed using a Von Frey test reflecting chronic hypoalgesia. Tolerance to treatment was assessed with a clinical score including four items: weight loss, weariness, alopecia, and diarrhea. In vitro, Mn1C1A associated with oxaliplatin and Pt(IV) conjugates treatment induced significantly higher production of H₂O₂ in all cell lines and showed a significant improvement of the antitumoral efficacy compared to oxaliplatin alone. In vivo, the association of Mn1C1A to oxaliplatin did not decrease its antitumoral activity, while OxPt-2-Mn1C1A had lower antitumoral activity than oxaliplatin alone. Mn1C1A associated with oxaliplatin significantly decreased OIPN and also improved global clinical tolerance of oxaliplatin. A neuroprotective effect was observed, associated with a significantly improved tolerance to oxaliplatin without impairing its antitumoral activity.

Graft-versus-host disease (GVHD) is a life-threatening systemic complication of allogeneic hematopoietic stem cell transplantation (HSCT) characterized by dysregulation of T and B cell activation and function, scleroderma-like features, and multi-organ pathology. The treatment of cGVHD is limited to the management of symptoms and long-term use of immunosuppressive therapy, which underscores the need for developing novel treatment approaches. Notably, there is a striking similarity between cytokines/chemokines responsible for multi-organ damage in cGVHD and pro-inflammatory factors, immune modulators, and growth factors secreted by senescent cells upon the acquisition of senescence-associated secretory phenotype (SASP). In this pilot study, we questioned the involvement of senescent cell-derived factors in the pathogenesis of cGVHD triggered upon allogeneic transplantation in an irradiated host. Using a murine model that recapitulates sclerodermatous cGVHD, we investigated the therapeutic efficacy of a senolytic combination of dasatinib and quercetin (DQ) administered after 10 days of allogeneic transplantation and given every 7 days for 35 days. Treatment with DQ resulted in a significant improvement in several physical and tissue-specific features, such as alopecia and earlobe thickness, associated with cGVHD pathogenesis in allograft recipients. DQ also mitigated cGVHD-associated changes in the peripheral T cell pool and serum levels of SASP-like cytokines, such as IL-4, IL-6 and IL-8Rα. Our results support the involvement of senescent cells in the pathogenesis of cGVHD and provide a rationale for the use of DQ, a clinically approved senolytic approach, as a potential therapeutic strategy.