New analysis from the Phase 3 IMerge clinical trial, accepted as an oral presentation, explores relationship between treatment-emergent cytopenias and clinical response in LR-MDS

Additional poster presentations include long-term survival outcomes, translational biomarker analyses, and an update on combination therapy trial in myelofibrosis

Geron Corporation (Nasdaq: GERN), a commercial-stage biopharmaceutical company aiming to change lives by changing the course of blood cancer, today announced that five abstracts – one oral and four poster presentations – have been accepted for presentation at the 67^th American Society of Hematology (ASH) 2025 Annual Meeting, to be held December 6-9, 2025 in Orlando, FL. The data feature new clinical and translational analyses of RYTELO (imetelstat) across lower-risk myelodysplastic syndromes/neoplasms (LR-MDS) and myelofibrosis (MF).

“The ASH 2025 presentations reflect growing scientific momentum around imetelstat and telomerase inhibition,” said Joseph E. Eid, M.D., Executive Vice President, Research and Development and Chief Medical Officer of Geron. “Across multiple analyses, we continue to see evidence of imetelstat’s potential to deliver durable and biologically meaningful outcomes in both lower-risk MDS and myelofibrosis. We look forward to presenting these data and continuing to inform physicians and patients on the benefits of RYTELO.”

Accepted Presentations

Oral Presentation (LR-MDS)

• Abstract #490: Correlation between Treatment-Emergent Cytopenias and Clinical Response with Imetelstat (IME) in Patients (Pts) with Lower-Risk Myelodysplastic Syndromes (LR-MDS): Analysis from the IMerge Trial
  
  Presenter: Amer Zeidan, MBBS, MHS, Chief of the Division of Hematologic Malignancies and Professor of Medicine at Yale University
  
  Presentation Date and Time: December 7, 2025, 10:00-10:15 AM ET

“In hematology, the emergence of cytopenias can reflect a therapy’s biological activity within the bone marrow,” said Amer Zeidan, Chief of the Division of Hematologic Malignancies and Professor of Medicine at Yale University. “Our analysis explores how early treatment-emergent cytopenias with imetelstat are on target and may relate to clinical response, helping to inform how we interpret treatment patterns and patient management in this setting. Together with other studies being presented at ASH, these findings continue to build a deeper scientific understanding of telomerase inhibition and its relevance in myeloid malignancies.”

Poster Presentation (LR-MDS)

• Publication #2074: Long-Term Outcomes from Randomized, Double-Bind, Placebo-Controlled, Phase 3 IMerge Trial of Imetelstat for Lower-Risk Myelodysplastic Syndromes (LR-MDS)
  
  Presenter: Valeria Santini, M.D., Associate Professor of Hematology at the University of Florence Medical School
  
  Session Date and Time: December 6, 2025, 5:30 PM - 7:30 PM ET

This abstract evaluates long-term follow-up data from the IMerge trial, which is the foundation of imetelstat’s approval in the U.S. and EU. Although the 42-month landmark analysis was not pre-specified, the totality of the data and the results of an overall survival OS analysis (≥42 months) suggest a favorable trend for imetelstat in OS, progression-free survival and time to progression to AML, compared to placebo.

Poster Presentations (MF)

• Publication #5585: Correlation between Interleukin (IL)-8 and Tumor Necrosis Factor (TNF)-Alpha Levels and Overall Survival in Patients (Pts) with Myelofibrosis (MF) Relapsed or Refractory (R/R) to a Janus-Associated Kinase Inhibitor (JAKi) Treated with Imetelstat (IME) in the IMbark Trial
  
  Presenter: John Mascarenhas, M.D., Professor of Medicine at the Icahn School of Medicine at Mount Sinai
  
  Session Date and Time: December 8, 2025, 6:00 PM - 8:00 PM ET

This abstract is a new exploratory analysis using data from the Phase 2 IMbark trial of imetelstat in relapsed/refractory MF. This hypothesis-generating analysis identified dose-dependent reductions in specific inflammatory cytokines with imetelstat from baseline which, taken together with previously presented data, suggests potential disease-modifying activity in MF.

• Publication #2052: IMproveMF: Phase 1b Trial of Imetelstat Plus Ruxolitinib in Patients with Intermediate-2 or High-Risk Myelofibrosis
  
  Presenter: John Mascarenhas, M.D., Professor of Medicine at the Icahn School of Medicine at Mount Sinai
  
  Session Date and Time: December 6, 2025, 5:30 PM - 7:30 PM ET

This abstract is sharing the trial design for the expansion portion of the IMproveMF Phase 1b trial of imetelstat and ruxolitinib in high-risk MF. The first treatment visit has occurred, and enrollment is ongoing.

Poster Presentation (Investigator Sponsored: HR-MDS and AML)

• Publication #5115: A Phase II Study Evaluating the Efficacy and Safety of Imetelstat in Patients with Advanced Myelodysplastic Neoplasms or AML Failing HMA-based Therapy: Interim Analysis Results of the IMpress Study
  
  Presenter: Lionel Ades, M.D., Ph.D., Professor of Hematology, Paris University - Hospital Saint-Louis
  
  Session Date and Time: December 8, 2025, 6:00 - 8:00 PM ET

This abstract presents interim results from an investigator-led study exploring imetelstat in high-risk MDS. The results suggest that imetelstat has limited single agent activity in this group, with one patient remaining on study.

Dr. Zeidan has served as a consultant for Geron and has received honoraria. The views expressed in this press release and in the presentation are his own and do not necessarily reflect those of his employer.

About Geron

Geron is a commercial-stage biopharmaceutical company aiming to change lives by changing the course of blood cancer. Our first-in-class telomerase inhibitor RYTELO® (imetelstat) is approved in the United States and the European Union for the treatment of certain adult patients with lower-risk myelodysplastic syndromes with transfusion dependent anemia. We are also conducting a pivotal Phase 3 clinical trial of imetelstat in JAK-inhibitor relapsed/refractory myelofibrosis, as well as studies in other myeloid hematologic malignancies. Inhibiting telomerase activity, which is increased in malignant stem and progenitor cells in the bone marrow, aims to reduce proliferation and induce death of malignant cells. To learn more, visit www.geron.com or follow us on LinkedIn.

Use of Forward-Looking Statements

Except for the historical information contained herein, this press release contains forward-looking statements made pursuant to the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. Investors are cautioned that such statements, include, without limitation, those regarding: (i) the Company’s belief in the growing scientific momentum around imetelstat and telomerase inhibition and continuing evidence of imetelstat’s potential to deliver durable and biologically meaningful outcomes in both lower-risk MDS and myelofibrosis; (ii) the Company’s plans to continue informing physicians and patients on the benefits of RYTELO; (iii) clinical data suggesting that early treatment-emergent cytopenias with imetelstat are on target and may relate to clinical response and that such data help inform how physicians interpret treatment patterns and patient management in treating lower-risk MDS patients; (iv) beliefs in the relevance of telomerase inhibition in myeloid malignancies; (v) the interpretations and expectations of the data on imetelstat presented at the ASH 2025 Annual Meeting; and (vi) other statements that are not historical facts, constitute forward-looking statements. These forward-looking statements involve risks and uncertainties that can cause actual results to differ materially from those in such forward-looking statements. These risks and uncertainties, include, without limitation, risks and uncertainties related to: (a) whether Geron is successful in commercializing RYTELO (imetelstat) for the treatment of certain patients with lower-risk MDS with transfusion dependent anemia and achieves market acceptance across the breadth of the eligible patient segments in RYTELO’s approved indication; (b) whether the FDA and European Commission will approve imetelstat for other indications on the timelines expected, or at all; (c) Geron’s plans to commercialize RYTELO in the European Union, or EU, and risks related to operating outside of the U.S.; (d) whether Geron overcomes potential delays and other adverse impacts that may be caused by enrollment, clinical, safety, efficacy, technical, scientific, intellectual property, manufacturing and regulatory challenges in order to have the financial resources for and meet expected timelines and planned milestones; (e) whether regulatory authorities permit the further development of imetelstat on a timely basis, or at all, without any clinical holds; (f) whether any future safety or efficacy results of RYTELO treatment cause its benefit-risk profile to become unacceptable; (g) whether imetelstat actually demonstrates disease-modifying activity in patients and the ability to target the malignant stem and progenitor cells of the underlying disease; (h) whether Geron meets its post-marketing requirements and commitments for RYTELO; (i) whether there are failures or delays in manufacturing or supplying sufficient quantities of RYTELO (imetelstat) or other clinical trial materials that impact commercialization of RYTELO or the continuation of clinical trials; (j) that the projected timing for the interim and final analyses of the Phase 3 IMpactMF trial in R/R MF may vary depending on actual death rates in the trial; and (k) whether Geron stays in compliance with and satisfies its obligations under its debt and synthetic royalty financing agreements. Additional information on the above risks and uncertainties and additional risks, uncertainties and factors that could cause actual results to differ materially from those in the forward-looking statements are contained in Geron’s filings and periodic reports filed with the Securities and Exchange Commission under the heading “Risk Factors” and elsewhere in such filings and reports, including Geron’s quarterly report on Form 10-Q for the quarter ended June 30, 2025, and subsequent filings and reports by Geron. Undue reliance should not be placed on forward-looking statements, which speak only as of the date they are made, and the facts and assumptions underlying the forward-looking statements may change. Except as required by law, Geron disclaims any obligation to update these forward-looking statements to reflect future information, events, or circumstances.

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