Geron Announces Presentations at ASCO and EHA Underscoring RYTELO® (imetelstat) Efficacy and Safety Across Range of LR-MDS Patients, and Showcasing Momentum of Myelofibrosis Program

New post-hoc analyses from the IMerge trial show clinical benefit with RYTELO across patients with lower-risk myelodysplastic syndromes (LR-MDS), regardless of ring sideroblast status, baseline serum erythropoietin (sEPO) level, or prior therapy use

Health-related quality-of-life (QOL) data and results on time without transfusion reliance (TWiTR) provide deeper insights into patient-centric outcomes with RYTELO in LR-MDS

Updates on ongoing IMpactMF and IMproveMF trials of imetelstat show progress in advancing the science of telomerase inhibition in the treatment of myelofibrosis

Geron Corporation (Nasdaq: GERN), a commercial-stage biopharmaceutical company aiming to change lives by changing the course of blood cancer, today announced presentations on RYTELO^® (imetelstat) at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and the European Hematology Association (EHA) 2025 Congress. Together, the presentations reinforce the potential benefits of the first-in-class oligonucleotide telomerase inhibitor RYTELO for a range of patients with lower-risk myelodysplastic syndromes (LR-MDS) with transfusion-dependent anemia and showcase the progress Geron is making with the ongoing IMpactMF and IMproveMF trials of imetelstat in myelofibrosis (MF).

“Transfusion independence is an important goal for LR-MDS patients, but one that historically has not been achievable for many,” said Rami S. Komrokji, M.D., Vice Chair, Malignant Hematology Department, Moffitt Cancer Center. “While imetelstat is already playing a vital role in LR-MDS, these new analyses being presented at ASCO and EHA reinforce its potential to give a broad range of patients more time without transfusions and should also give clinicians confidence to add it to their toolkit as a second-line option for eligible patients.”

Presentations at ASCO and EHA include:

New pooled, post-hoc analyses expand on the pivotal IMerge results across challenging LR-MDS subpopulations

• Analysis of patients with ring sideroblast negative (RS-) disease, showing that these difficult-to-treat patients appeared to experience clinical benefit with RYTELO, including ≥8-week, ≥24-week and ≥1-year red blood cell transfusion independence (RBC-TI), duration of RBC-TI, and hemoglobin rise in patients who achieved RBC-TI, consistent with prior findings from the overall Phase 3 IMerge population.
• Analysis showing clinical benefit with RYTELO regardless of baseline serum erythropoietin (sEPO) level, supporting the use of RYTELO in the frontline setting for LR-MDS patients ineligible for erythropoiesis-stimulating agents (ESAs), and in the second-line setting after ESAs regardless of sEPO.
• Analysis showing clinical benefit with RYTELO in ESA-ineligible or relapsed/refractory patients regardless of prior treatment with luspatercept or lenalidomide. Patients who had prior treatment with a hypomethylating agent (HMA) showed modest clinical activity with RYTELO.

Patient-centric outcome measures offering deeper insight on RYTELO impact in new post-hoc analyses from Phase 3 IMerge trial

• Analysis showing that certain RYTELO-treated patients experienced sustained improvements in health-related quality-of-life (QOL) compared with placebo, as measured by certain categories in the patient-reported QOL in Myelodysplasia Scale (QUALMS) instrument.
• Exploratory analysis suggesting that certain patients treated with RYTELO experienced a longer mean duration of time without transfusion reliance or relapse (TWiTR), compared with placebo.

New updates on ongoing trials in MF

• Recently updated preliminary data from the dose escalation portion of the Phase 1/1b IMproveMF trial showing the combination of imetelstat and ruxolitinib was generally well-tolerated, with no dose-limiting toxicities observed as of the data cutoff date, and encouraging early dose-dependent efficacy data suggesting the potential of the combination for patients with intermediate-1 (INT-1), intermediate-2 (INT-2) or high-risk (HR) MF.
• Trial-in-progress (TiP) update on the Phase 3 IMpactMF trial investigating imetelstat in relapsed/refractory MF, reporting that the trial has met approximately 80% of its enrollment target as of February 2025.

“At ASCO and EHA, we’re excited to present new analyses on how RYTELO can deliver meaningful benefit across a range of LR-MDS patients who otherwise may have had limited options, whether due to their ring sideroblast status, baseline EPO level, or their treatment history,” said Faye Feller, M.D., Executive Vice President and Chief Medical Officer of Geron. “We believe the depth and breadth of our data reinforce the potential of RYTELO to address critical unmet needs in LR-MDS and, combined with the advances we are making with our myelofibrosis program, underscore our confidence in telomerase inhibition as a potentially transformative clinical strategy and our commitment to exploring its full potential.”

See below for a full schedule of presentations at ASCO and EHA.

ASCO 2025 Presentations

EHA 2025 Presentations

Please see the full presentations for important qualifications and limitations on these post-hoc analyses.

About RYTELO^® (imetelstat)

RYTELO is an oligonucleotide telomerase inhibitor approved in the U.S. for the treatment of adult patients with low-to-intermediate-1 risk myelodysplastic syndromes (LR-MDS) with transfusion-dependent anemia requiring four or more red blood cell units over eight weeks who have not responded to or have lost response to or are ineligible for erythropoiesis-stimulating agents (ESAs). It is indicated to be administered as an intravenous infusion over two hours every four weeks.

In addition, RYTELO is approved in the European Union as a monotherapy for the treatment of adult patients with transfusion-dependent anemia due to very low, low or intermediate risk myelodysplastic syndromes without an isolated deletion 5q cytogenetic (non-del 5q) abnormality and who had an unsatisfactory response to or are ineligible for erythropoietin-based therapy.

RYTELO is a first-in-class treatment that works by inhibiting telomerase enzymatic activity. Telomeres are protective caps at the end of chromosomes that naturally shorten each time a cell divides. In LR-MDS, abnormal bone marrow cells often express the enzyme telomerase, which rebuilds those telomeres, allowing for uncontrolled cell division. Developed and exclusively owned by Geron, RYTELO is the first and only telomerase inhibitor approved by the U.S. Food and Drug Administration and the European Commission.

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 (LR-MDS) with transfusion-dependent anemia. We are also conducting a pivotal Phase 3 clinical trial of imetelstat in JAK-inhibitor relapsed/refractory myelofibrosis (R/R MF), as well as studies in other hematologic malignancies. Inhibiting telomerase activity, which is increased in malignant stem and progenitor cells in the bone marrow, aims to potentially reduce proliferation and induce death of malignant cells. To learn more, visit www.geron.com or LinkedIn.

US IMPORTANT SAFETY INFORMATION ABOUT RYTELO^®

WARNINGS AND PRECAUTIONS

Thrombocytopenia

RYTELO can cause thrombocytopenia based on laboratory values. In the clinical trial, new or worsening Grade 3 or 4 decreased platelets occurred in 65% of patients with MDS treated with RYTELO.

Monitor patients with thrombocytopenia for bleeding. Monitor complete blood cell counts prior to initiation of RYTELO, weekly for the first two cycles, prior to each cycle thereafter, and as clinically indicated. Administer platelet transfusions as appropriate. Delay the next cycle and resume at the same or reduced dose, or discontinue as recommended.

Neutropenia

RYTELO can cause neutropenia based on laboratory values. In the clinical trial, new or worsening Grade 3 or 4 decreased neutrophils occurred in 72% of patients with MDS treated with RYTELO.

Monitor patients with Grade 3 or 4 neutropenia for infections, including sepsis. Monitor complete blood cell counts prior to initiation of RYTELO, weekly for the first two cycles, prior to each cycle thereafter, and as clinically indicated. Administer growth factors and anti-infective therapies for treatment or prophylaxis as appropriate. Delay the next cycle and resume at the same or reduced dose, or discontinue as recommended.

Infusion-Related Reactions

RYTELO can cause infusion-related reactions. In the clinical trial, infusion-related reactions occurred in 8% of patients with MDS treated with RYTELO; Grade 3 or 4 infusion-related reactions occurred in 1.7%, including hypertensive crisis (0.8%). The most common infusion-related reaction was headache (4.2%). Infusion-related reactions usually occur during or shortly after the end of the infusion.

Premedicate patients at least 30 minutes prior to infusion with diphenhydramine and hydrocortisone as recommended and monitor patients for at least one hour following the infusion as recommended. Manage symptoms of infusion-related reactions with supportive care and infusion interruptions, decrease infusion rate, or permanently discontinue as recommended.

Embryo-Fetal Toxicity

Based on animal findings, RYTELO can cause embryo-fetal harm when administered to a pregnant woman. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with RYTELO and for 1 week after the last dose.

ADVERSE REACTIONS

Serious adverse reactions occurred in 32% of patients who received RYTELO. Serious adverse reactions in >2% of patients included sepsis (4.2%) and fracture (3.4%), cardiac failure (2.5%), and hemorrhage (2.5%). Fatal adverse reactions occurred in 0.8% of patients who received RYTELO, including sepsis (0.8%).

Most common adverse reactions (≥10% with a difference between arms of >5% compared to placebo), including laboratory abnormalities, were decreased platelets, decreased white blood cells, decreased neutrophils, increased AST, increased alkaline phosphatase, increased ALT, fatigue, prolonged partial thromboplastin time, arthralgia/myalgia, COVID-19 infections, and headache.

Please see RYTELO (imetelstat) full Prescribing Information, including Medication Guide, available at https://pi.geron.com/products/US/pi/rytelo_pi.pdf.

The Summary of Product Characteristics (SmPC) for RYTELO in the EU is available at https://pi.geron.com/products/rytelo/eu/rytelo_smpc_eu.pdf

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) that the new analyses presented at ASCO and EHA reinforce the potential benefits of RYTELO for a range of patients with LR-MDS with transfusion-dependent anemia, including its potential to give a broad range of patients more time without transfusions and should support clinician’s confidence in RYTELO as a second-line option for eligible patients; (ii) beliefs regarding imetelstat’s vital role in LR-MDS, (iii) how RYTELO can deliver meaningful benefit across a range of LR-MDS patients who otherwise may have had limited options, whether due to ring sideroblast status, baseline EPO levels, or their treatment history; (iv) Geron’s beliefs that the depth and breadth of its data reinforce the potential of RYTELO to address critical unmet needs in LR-MDS and regarding telomerase inhibition as a potentially transformative clinical strategy; and (v) 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 LR-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 its ongoing clinical trials, including the IMpactMF trial; (j) that the projected timing for the interim and final analyses of the IMpactMF trial may vary depending on actual enrollment and 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 March 31, 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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