Safety and Tolerability of REGN17235 in Adults with Clonal Cytopenia of Undetermined Significance or Low‑Risk SF3B1‑Mutated Myelodysplastic Syndrome

The primary objective is to assess the safety and tolerability of REGN17235 in adult participants diagnosed with Clonal Cytopenia of Undetermined Significance and Low-Risk Myelodysplastic Syndrome harboring an SF3B1 mutation. This evaluation will determine the incidence and severity of adverse events, laboratory abnormalities, and treatment discontinuations associated with the investigational product, thereby informing the risk‑benefit profile for these conditions.

The trial enrolled 40 individuals diagnosed with either Clonal Cytopenia of Undetermined Significance or Low-Risk Myelodysplastic Syndrome harboring an SF3B1 mutation. Both male and female patients were included, representing adult age groups corresponding to the study’s predefined age categories (codes 3 and 4). All participants were classified as patients with the target hematologic conditions and were considered a vulnerable population under regulatory definitions. Enrollment required confirmation of the specified diagnoses and the presence of the SF3B1 mutation; no additional lifestyle restrictions such as diet or physical activity were reported. General health status was limited to the presence of the study conditions, and other comorbidities were not detailed in the provided information.

A Phase 1 study evaluating the safety and tolerability of REGN17235 in adults with clonal cytopenia of undetermined significance or low‑risk myelodysplastic syndrome carrying an SF3B1 mutation is conducted as a randomized, double‑blind design. The trial is scheduled to commence recruitment on 17 September 2026 and to complete on 5 May 2031. Eligible participants undergo an initial screening visit to confirm inclusion criteria, followed by a baseline assessment on day 0. Subsequent scheduled visits are performed at regular intervals to monitor adverse events, laboratory parameters, and drug exposure, culminating in a final end‑of‑study visit that concludes participant involvement. Participants remain in the study until the end‑of‑study visit unless discontinuation occurs in accordance with protocol‑defined criteria.