CERo Therapeutics Announces Clinical Update from CERTAIN-T Phase 1 CER-1236 Trial, Including Patient Undergoing Allogeneic Stem Cell Transplant Following Treatment

Fifth patient treated with CER-1236 underwent stem cell transplant following lack of response to prior therapies; Company initiates third planned cohort in ongoing Phase 1 study in hematologic malignancies

SOUTH SAN FRANCISCO, Calif, June 15, 2026 (GLOBE NEWSWIRE) -- CERo Therapeutics Holdings, Inc. (OTCQB:CERO) ("CERo" or the "Company"), an innovative cellular immunotherapy company advancing engineered T cell therapeutics designed to engage phagocytic mechanisms, today announced a clinical update from investigators participating in the ongoing Phase 1 CERTAIN-T clinical trial evaluating CER-1236 in hematologic malignancies.

Patient five in the trial had multiple refractory acute myeloid leukemia (AML) and, according to the treating investigator, had not previously achieved disease control sufficient to enable allogeneic stem cell transplantation prior to enrollment in the study. Following treatment with CER-1236 at a total dose of 4 million cells/kg, bone marrow blast counts were reported at 14% on Days 14 and 28 and 7% on Day 42. The patient subsequently underwent allogeneic stem cell transplantation on Day 71 following infusion. Allogeneic stem cell transplantation is generally considered a potentially curative therapeutic option for eligible patients with refractory hematologic malignancies and remains a critical component of treatment for many patients with relapsed or treatment-resistant disease.

The patient's transplant course and longer-term clinical outcome remain under evaluation. These observations are preliminary, based on a limited number of patients, and no definitive conclusions regarding safety or efficacy can be made at this stage of the trial.

Chris Ehrlich, CEO of CERo, commented, "We continue to observe encouraging findings from the ongoing trial, with investigators reporting clinical improvement in two patients treated across the first two cohorts. Although formal response assessments remain ongoing, investigators have reported findings suggestive of clinical benefit following treatment with CER-1236. We look forward to continuing dose escalation and further evaluating CER-1236 in the ongoing Phase 1 study."

The observed safety profile across all treated patients remains consistent with clinical data previously presented at the Tandem Meetings in February, which reported no cytokine release syndrome ("CRS"), immune effector cell-associated neurotoxicity syndrome ("ICANS"), DLTs, or treatment-related severe adverse events during the DLT assessment window.

The Company has now treated six patients in the ongoing Phase 1 trial. In the most recent cohort of three patients, CER-1236 was administered at an increased dose level, with no dose-limiting toxicities ("DLTs") observed during the DLT assessment period. As previously reported, CERo has also observed expansion of infused CER-1236 cells following administration, and the Company continues to evaluate the pharmacokinetic and pharmacodynamic profile of CER-1236 as the study advances through dose escalation.

The Company has initiated the third planned cohort of the CERTAIN-T study, which is expected to evaluate the planned one billion cells/patient protocol and is currently screening patients for enrollment. The cohort is also expected to include patients with myelodysplastic syndromes ("MDS") and myelofibrosis ("MF"), reflecting the Company's strategy to further evaluate CER-1236 in additional myeloid disease settings.

About the CERTAIN-T Trial

The first-in-human, multicenter, open-label Phase 1/1b CERTAIN-T study is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity of CER-1236 in patients with hematologic malignancies. The study initially enrolled patients with acute myeloid leukemia ("AML"), including relapsed/refractory AML, measurable residual disease AML, and newly diagnosed TP53-mutated AML, and has since expanded to include transfusion-dependent myelodysplastic syndromes ("TD-MDS"), high-risk myelodysplastic syndromes ("HR-MDS"), and post-JAK inhibitor myelofibrosis ("MF"). Primary endpoints include safety and tolerability. 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").

About CERo Therapeutics Holdings, Inc.

CERo Therapeutics Holdings, Inc. is an innovative immunotherapy company advancing the development of engineered T cell therapeutics for the treatment of cancer. The Company's proprietary approach to T cell engineering is designed to integrate characteristics of innate and adaptive immunity into a single therapeutic construct intended to engage multiple immune mechanisms against cancer. CERo refers to these engineered cells as Chimeric Engulfment Receptor T cells ("CER-T").

The Company's lead investigational product candidate, CER-1236, is being evaluated in hematologic malignancies.

Forward-Looking Statements

This communication contains forward-looking statements within the meaning of applicable securities laws. These statements include, without limitation, statements regarding the clinical development, safety profile, pharmacokinetic and pharmacodynamic characteristics, therapeutic potential, and future evaluation of CER-1236; the progression, design, and enrollment of the CERTAIN-T trial; planned cohort expansion and dose escalation; and the Company's development strategy and objectives. These statements are based on current expectations and assumptions and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements.

Certain risks that could cause actual results to differ are set forth in CERo's filings with the Securities and Exchange Commission, including its most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q, and the documents incorporated by reference therein. The risks described in CERo's filings with the Securities and Exchange Commission are not exhaustive. Forward-looking statements are not guarantees of performance, and undue reliance should not be placed on such statements. CERo undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by law.

Contact:

Chris Ehrlich

Chief Executive Officer

[chris@cero.bio](mailto:chris@cero.bio)

Investors:

CORE IR

[investors@cero.bio](mailto:investors@cero.bio)