Background Chronic inflammation is a key driver of disease progression in myelodysplastic syndromes (MDS), contributing to ineffective hematopoiesis and increasing the risk of transformation to secondary acute myeloid leukemia (sAML). In low-risk MDS (LR-MDS), aberrant activation of innate immune pathways triggers activation of the NLRP3 inflammasome in hematopoietic stem and progenitor cells. This results in caspase-1 mediated release of pro-inflammatory cytokines including IL-1β and IL-18. These cytokines propagate downstream inflammatory signaling in the bone marrow, including upregulation of IL-6 and IL-8. IL-1β acts as an upstream mediator of bone marrow inflammation and is frequently elevated in both hematopoietic and innate immune cells in MDS, while IL-6 plays a multifaceted role in regulating hematopoietic differentiation and survival. IL-8, a key effector produced by monocytes, macrophages, and stromal cells in response to IL-1β and TNF-α, has been associated with ineffective hematopoiesis, transfusion dependence, and resistance to erythropoiesis-stimulating agents in MDS.

Ofirnoflast (HT-6184) is a first-in-class, orally bioavailable allosteric inhibitor of NEK7 which is a key component in the NLRP3 inflammasome activation pathway. Preclinically, HT-6184 reduces IL-1β, IL-6, and IL-8 production in THP-1 cells, a cell line derived from a patient with AML, human peripheral blood mononuclear cells, and human whole blood, from healthy individuals. We hypothesized that cytokine levels would decrease in patients with LR-MDS receiving ofirnoflast in an ongoing two-stage Phase 2a clinical trial (NCT07052006).

Methods This analysis includes the initial cohort of 18 patients evaluable for erythroid response enrolled in Stage 1 of the ongoing Phase 2 trial. Patients self-administered ofirnoflast daily for five consecutive days, followed by a two-day drug holiday, weekly for 16 weeks. Patients without disease progression after 16 weeks were allowed to continue treatment for an additional 16 weeks, for a maximum of 32 weeks. Serum IL-8, IL-1β, and IL-6 were measured by ELISA at baseline, Week 16, and end of Week 32. Percent change from baseline was calculated for each cytokine at each timepoint. Hematologic improvement–erythroid (HI-E), per IWG 2018 criteria, was assessed at weeks 16 and 32, and cytokine trends were summarized by erythroid response status.

Results In this cohort of patients, baseline IL-8 levels ranged from 3.6 to 481.6 pg/mL, with a median of 12.8 pg/mL (normal reference range ≤35 pg/mL). Among 18 subjects who received at least 16 weeks of treatment with ofirnoflast, 13 (72%) exhibited erythroid response. In these responders (n=13), IL-8 levels decreased by a median of 16.2% by Week 32, reflecting a downward trend. In contrast, non-responders (n=2) exhibited a median IL-8 decrease of only 9% at Week 32. Across the cohort, there was an overall 16.2% median reduction in IL-8 levels from baseline to end of study, with the decrease slightly maintained when looking at subjects with an erythroid response (16.2%) compared to those without (9%). IL-1β levels at baseline ranged from 2.11 to 181.56 pg/mL (median 9.37 pg/mL; reference range <5 pg/mL). Three patients had IL-1β levels >100 pg/mL at baseline, two of whom achieved HI-E. All three experienced >90% reductions in IL-1β by Week 16 that were maintained through the end of treatment (Week 32). No consistent trends were observed for IL-6.

Conclusions Treatment with ofirnoflast was associated with modulation in serum levels of inflammatory cytokines, particularly IL-8 and IL-1β, in patients with low-risk MDS, particularly among patients achieving hematologic improvement. These findings support further evaluation of inflammasome modulation as a potential strategy to improve hematopoiesis in LR-MDS. Additionally, Larger studies with expanded sampling will clarify the therapeutic relevance of cytokine reduction in LR-MDS.

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2025
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