CERo Therapeutics Completes Second Ascending Dose Cohort of Phase 1 CER-1236 Trial

Company to initiate third planned cohort at higher dose level, including patients with myelodysplastic syndrome and myelofibrosis

SOUTH SAN FRANCISCO, Calif., May 11, 2026 (GLOBE NEWSWIRE) -- CERo Therapeutics Holdings, Inc. (OTCQB:CERO) ("CERo" or the "Company"), an innovative cellular immunotherapy company advancing next-generation engineered T cell therapeutics that employ phagocytic mechanisms, announces that it has completed dosing and the 28-day dose-limiting toxicity ("DLT") assessment period for all three patients in the second cohort of its Phase 1 CERTAIN-T clinical trial of CER-1236 in hematologic malignancies.

In the second cohort, patients received CER-1236 at a total dose of 4 × 10⁶ cells/kg, administered as a split dose on Day 0 and Day 2. No DLTs were observed through the DLT assessment window, supporting continued dose escalation in accordance with the clinical protocol. The observed safety profile remains consistent with clinical data 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.

CERo is now escalating to the planned 1 × 10⁷ cells/kg split-dose cohort and is screening patients for enrollment. This next cohort is expected to include patients with myelodysplastic syndrome ("MDS") and myelofibrosis ("MF"), reflecting the Company's strategy to evaluate CER-1236 in myeloid disease settings characterized by inflammatory bone marrow microenvironments and impaired hematopoiesis.

The Company has now treated six patients in its 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 observed during the DLT assessment period. As previously reported, CERo has also observed expansion of infused CER-1236 cells following administration, supporting continued evaluation of CER-1236's pharmacokinetic and pharmacodynamic profile as the study advances through dose escalation.

Robert Sikorski, M.D., Ph.D., CERo Chief Medical Officer, stated, "We are encouraged by the continued progress of the CERTAIN-T study, including completion of the second dose cohort and advancement to the next planned dose level. As we proceed in accordance with the clinical protocol, our priority remains the careful evaluation of the safety, tolerability, pharmacokinetic profile, and preliminary clinical activity of CER-1236. The planned inclusion of patients with MDS and MF reflects our interest in exploring CER-1236 across additional hematologic malignancies with significant unmet need and further assessing the potential of its differentiated phagocytic CAR-T mechanism."

The first-in-human, multicenter, 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 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, "The advancement of CER-1236 through dose escalation continues at a steady pace and we remain focused on evaluating its potential across hematologic malignancies with significant unmet need. We look forward to providing additional clinical updates as the study progresses."

About CERo Therapeutics Holdings, Inc.

CERo is an innovative immunotherapy company advancing the development of next generation engineered T cell therapeutics for the treatment of cancer. Its proprietary approach to T cell engineering, which enables it to integrate certain desirable characteristics of both innate and adaptive immunity into a single therapeutic construct, is designed to engage the body's full immune repertoire to achieve optimized cancer therapy. This novel cellular immunotherapy platform is expected to redirect patient-derived T cells to eliminate tumors by building in engulfment pathways that employ phagocytic mechanisms to destroy cancer cells, creating what CERo refers to as Chimeric Engulfment Receptor T cells ("CER-T"). CERo believes the differentiated activity of CER-T cells will afford them greater therapeutic application than currently approved chimeric antigen receptor ("CAR-T") cell therapy, as the use of CER-T may potentially span both hematological malignancies and solid tumors. CERo has commenced clinical trials for its lead product candidate CER-1236 for hematological malignancies.

Forward-Looking Statements

This communication contains statements that are forward-looking and as such are not historical facts. This includes, without limitation, statements regarding the financial position, business strategy and the plans and objectives of management for future operations of CERo. These statements constitute projections, forecasts and forward-looking statements, and are not guarantees of performance. Such statements can be identified by the fact that they do not relate strictly to historical or current facts. When used in this communication, words such as "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "might," "plan," "possible," "potential," "predict," "project," "should," "strive," "would" and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. When CERo discusses its strategies or plans, it is making projections, forecasts or forward-looking statements. Such statements are based on the beliefs of, as well as assumptions made by and information currently available to, CERo's management.

Actual results could differ from those implied by the forward-looking statements in this communication. 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. New risk factors emerge from time to time, and it is not possible to predict all such risk factors, nor can CERo assess the impact of all such risk factors on its business, or the extent to which any factor or combination of factors may cause actual results to differ materially from those contained in any forward-looking statements. Forward-looking statements are not guarantees of performance. You should not put undue reliance on these statements, which speak only as of the date hereof. All forward-looking statements made by CERo or persons acting on its behalf are expressly qualified in their entirety by the foregoing cautionary statements. CERo undertakes no obligation to update or revise publicly 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

Investors:

CORE IR

investors@cero.bio