SP-2509

The noncompetitive lysine-specific demethylase 1 (LSD1) inhibitors SP-2509 and SP-2577 are N'-(1-phenylethylidene)-benzohydrazides that display potent activity in Ewing sarcoma. This unique activity is instead associated with the N'-(2-hydroxybenzylidene)-benzohydrazide core and destabilization of Fe-S proteins. These findings reveal a novel mechanism of action for this class of compounds and raise additional questions regarding how EWSR1::FLI1 transcriptional regulation is linked to Fe-S biogenesis, the precise mechanisms of cell death, the biological features of susceptible cancer cells, and strategies for clinical translation.

Treatment with the small molecule SP-2509 results in reversal of the transcriptional activity of the FET fusion that causes Ewing sarcoma, EWSR1::FLI1. This included reversal of FET-fusion transcriptional signatures for EWSR1::WT1, EWSR1::ATF1, and EWSR1::ERG. Though novel inhibitors are unlikely to display single-agent efficacy in the clinic, these data suggest seclidemstat remains a promising new treatment strategy for patients with FET-rearranged and other fusion positive sarcomas.

The noncompetitive LSD1 inhibitors SP-2509 and SP-2577 are N'-(1-phenylethylidene)-benzohydrazides that display potent activity in Ewing sarcoma. This unique activity is instead associated with the N'-(2-hydroxybenzylidene)-hydrazide core and destabilization of Fe-S proteins. These findings reveal a novel mechanism of action for this class of compounds and raise additional questions regarding how EWSR1::FLI1 transcriptional regulation is linked to Fe-S biogenesis, the precise mechanisms of cell death, the biological features of susceptible cancer cells, and strategies for clinical translation.

LSD1 inhibition by SP2509 disrupted cell cycle, reduced immunosuppression, and enhanced CD4+ and CD8+ T-cell infiltration. In a feline model of spontaneous OSCC, a clinical LSD1 inhibitor (Seclidemstat or SP2577) was found to be safe and effectively inhibit the STAT3 network...Notably, LSD1 inhibition reduced the phosphorylation of CDK7 at Tyr170 and eIF4B at Ser422, offering insights into a novel mechanism by which LSD1 regulates the preneoplastic-to-OSCC transition. This study provides a deeper understanding of OSCC progression and highlights LSD1 as a potential therapeutic target for controlling OSCC progression from preneoplastic lesions.

SP2509, a histone demethylase inhibitor, effectively reversed the downregulation of lysosomal and mitochondrial genes caused by loss of Men1. Our study confirms the previously unrecognized biological and mechanistic importance of menin-mediated H3K4me3 in maintaining organelle homeostasis.

Notably, we report that SP2509, an allosteric inhibitor of the demethylase-independent function of LSD1 (a TBX2-interacting protein in the COREST complex) disrupts both TBX2-LSD1 and TBX2-GR protein-protein interactions, revealing a unique mode of SP2509 action in CRPC. Taken together, our study identifies the TBX2-driven AR- to GR- signaling switch as a molecular mechanism underlying enzalutamide resistance and provides key insights into a potential therapeutic approach for targeting this switch by disrupting TBX2-GR and TBX2-LSD1 protein-protein interactions.

Western blot analysis show that treatment with chemotherapy drugs cisplatin, carboplatin, and paclitaxel increased KDM1A expression in OCa cells. KDM1A knockdown (KD) or treatment with KDM1A inhibitors NCD38 and SP2509 sensitized established and patient-derived OCa cells to chemotherapy drugs in reducing cell viability and clonogenic survival and inducing apoptosis...Importantly, KDM1A-KD, in combination with cisplatin, significantly reduced tumor growth compared to a single treatment in an orthotopic intrabursal OCa xenograft model. Collectively, these findings suggest that combination of KDM1A inhibitors with chemotherapy could be a promising therapeutic approach for the treatment of OCa.

We further demonstrated that SP-2509 and OG-L002 disturbed fatty acid metabolism and induced lipid droplet accumulation through the impairment of lipophagy, but not bulk autophagy. These findings indicate a significant potential association of lipophagy and anticancer effects in glycolysis-suppressed PDAC cells, offering ideas for new therapeutic strategies for PDAC by dual inhibition of glycolysis and fatty acids metabolism.

The present study preclinically demonstrated that LSD1 inhibition could provide a valuable strategy to enhance PI sensitivity and overcome drug resistance in MM patients and that this combination might be exploited for the treatment of other B-cell malignancies, thus extending the therapeutic impact of the project.

Using our ZEB2 ETP-ALL mouse model we previously documented the potential utility of the catalytic LSD1 inhibitor (GSK2879552) for treating mouse/human ETP-ALL...Treatment with LSD1i (particularly with the steric inhibitor SP2509) restored the expression of ZEB2/LSD1 pro-apoptotic BIM (BCL2L11) target. In combination with a JAK/STAT pathway inhibitor (JAKi, Ruxolitinib) or with a direct inhibitor of the anti-apoptotic BCL2 protein (BCL2i, ABT-199) resistance of human and mouse ETP-ALL to LSD1i was reversed. This new combination approach efficiently inhibited the growth of human and mouse ETP-ALL cells in vivo by enhancing their differentiation and triggering an apoptotic response. These results set the stage for novel combination therapies to be used in clinical trials to treat ETP-ALL patients.

We demonstrated that LSD1 is overexpressed in RB cells and promotes RB cell survival. The LSD1 inhibitor SP2509 exerted strong growth inhibition in vitro and in vivo, which was at least partially mediated by suppression of the β-catenin pathway.