Study will advance into expanded patient populations with myelodysplastic syndrome (MDS) and myelofibrosis (MF)

SOUTH SAN FRANCISCO, Calif., April 15, 2026: CERo Therapeutics Holdings, Inc., (OTCQB: CERO) (“CERo” or the “Company”) an innovative cellular immunotherapy company seeking to advance the next generation of engineered T cell therapeutics that employ phagocytic mechanisms, announces it has dosed the third patient in the second cohort (sixth patient overall) in its Phase 1 CER-1236 clinical trial in hematologic malignancies. The patient had MDS that evolved to acute myeloid leukemia (AML). The trial was recently expanded to include earlier forms of MDS and myelofibrosis (MF).

The study continues to progress in accordance with protocol, with patients undergoing monitoring for safety, pharmacokinetics, pharmacodynamics, and clinical activity. With more than seven days of follow-up completed after the most recent infusion, CERo continues to evaluate key endpoints across dose levels as it advances through dose escalation.

As previously presented at the February Tandem Meetings in Salt Lake City, CER-1236 has demonstrated no reported cases of cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS) of any grade, and no dose-limiting toxicities observed during the 28-day assessment window. Investigators also reported in vivo cell expansion, with peak levels observed between days 10 and 14 following infusion. Additionally, as previously reported, a single patient with inv(3) AML who received four CER-1236 infusions over five months at the lowest dose level achieved 72 consecutive days of platelet transfusion independence. These findings informed the protocol amendment expanding enrollment into patients with MDS and MF.

Robert Sikorski, M.D., Ph.D., CERo Chief Medical Officer, stated, “This is the third patient in the cohort, and completion of the dose-limiting toxicity evaluation period may enable further dose escalation in accordance with the protocol. We continue to evaluate the safety profile and early clinical data as CER-1236 is studied in patient populations with significant unmet need.”

The first-in-human, multi-center, open-label Phase 1/1b study is designed to evaluate the safety and preliminary efficacy of CER-1236. The trial was initially focused on AML patients, including those with relapsed/refractory disease, measurable residual disease, or newly diagnosed TP53-mutated AML, and has since expanded to include transfusion-dependent MDS (TD-MDS), high-risk MDS (HR-MDS), and post-JAK inhibitor myelofibrosis (MF). Primary endpoints include safety and tolerability, while secondary endpoints include pharmacokinetics and measures of clinical response, including overall response rate (ORR), complete response (CR), composite complete response (cCR), and measurable residual disease (MRD).

CERo Chief Executive Officer Chris Ehrlich added, “Dosing our sixth patient and expanding into MDS represents continued execution of the CERTAIN-T trial and an important milestone for CERo. We believe CER-1236 has the potential to address multiple hematologic malignancies, and we look forward to further advancing the study and sharing additional clinical updates.”