Preclinical data posters presented at EHA Congress

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Poolbeg Pharma PLC announced new preclinical data for its POLB 001 drug candidate at the European Hematology Association Congress. The research indicates POLB 001's potential to prevent cytokine release syndrome (CRS) by reducing key inflammatory cytokines without impairing tumor cell death, and also suggests a new indication for POLB 001 in improving outcomes for elderly Acute Myeloid Leukemia (AML) patients when combined with Azacitidine. These findings reinforce POLB 001's utility as a preventative therapy for cancer immunotherapy-induced CRS and highlight its potential to enhance AML treatment efficacy.

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Posters highlight POLB 001's potential in CRS prevention and ability to enhance AML treatment in elderly patients, potentially expanding into a new indication

First poster shows that POLB 001 decreased key CRS-associated cytokines and did not impair bispecific antibody-induced tumour cell death in a series of preclinical investigations
Second poster demonstrates the potential for POLB 001 to improve outcomes for elderly AML patients, positioning AML as a potential new indication for POLB 001

11 June 2026 - Poolbeg Pharma (AIM: POLB, 'Poolbeg' or the 'Company'), a clinical-stage biopharmaceutical company with a core focus on transforming the cancer immunotherapy field, announces new research on two posters, by Poolbeg and The University of Manchester respectively, are being presented at the European Hematology Association Congress ("EHA"), in Stockholm, Sweden which runs from Thursday 11 June until Sunday 14 June 2026.

Poster on the in vitro and in vivo effects of POLB 001 on cytokine release syndrome ("CRS") and T cell phenotype and function

This poster, presented by Poolbeg, details the in vitro and in vivo effects of POLB 001 on cytokine release syndrome ("CRS") and T cell phenotype and function. The in vitro studies utilised primary human blood samples co-cultured with a human tumour cell line and two commercially available bispecific antibodies ("BsAb"). The in vivo study assessed the impact of prophylactic POLB 001 in a humanised tumour-bearing mouse model of BsAb induced CRS.

Key highlights:

·	POLB 001 did not affect BsAb -induced tumour cell-killing in an in vitro model
·	POLB 001 reduced key CRS-associated cytokines
·	POLB 001 significantly decreased peak serum levels of TNF, IFNγ, and IL-6 in an in vivo model of BsAb induced-CRS
·	These positive results reinforce the use case for POLB 001 as a preventative therapy for cancer immunotherapy-induced CRS

Title: POLB 001, an oral p38 MAPK Inhibitor for the Prevention of Cytokine Release Syndrome

Poster Session: Poster Session 2, Hall A

Session Date and Time: Saturday, 13 June 2026, 18:45 - 19:45 CEST

Authors: L. Tremble, P. Maguire, M. Arora, J. Froggatt, J. Skillington, B. Buckley, R. Popat, E. Searle.

Abstract Code: PS1845

Poster on the potential for POLB 001 to improve outcomes for elderly AML patients

This poster, presented by The University of Manchester, highlights the potential for POLB 001 to improve outcomes for elderly Acute Myeloid Leukaemia ("AML") patients in combination with Azacitidine ("AZA"). The key findings from this in vivo study provide early preclinical evidence that POLB 001 may enhance the efficacy of azacitidine in aged mouse models of AML. Azacitidine is a first-line treatment offered to patients with AML.

Poster 2 Presentation Details:

Title: Targeting inflammation via p38MAPK inhibition to improve azacitidine efficacy in aged AML

Poster Session: Poster Session 2, Hall A

Session Date and Time: Saturday 13 June 2026, 18:45 - 19:45 CEST

Authors: A. Vitlic, S. Menegatti, W. Yang, Z. Jia, S. Nickaria, L. Tremble, P. Maguire, S. Valletta

Abstract Code: PS1565

Liam Tremble, Principal Scientist of Poolbeg Pharma, said: " This novel data in CRS reinforces the potential of POLB 001 to address one of the most significant challenges associated with cancer immunotherapy. We believe POLB 001 could play an important role in improving both the safety and accessibility of these transformative therapies, and we look forward to sharing interim data from the TOPICAL trial in multiple myeloma patients later this summer. The results in preclinical models of AML generated and being presented at EHA by the University are highly encouraging and point to the potential clinical utility of POLB 001 beyond CRS. AML is a disease of the elderly and current treatment strategies are poorly suited for a frail patient population"

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