Investigator-sponsored study, conducted at the Moffitt Cancer Center, demonstrates safety and efficacy consistent with the Phase 3 IMerge trial in a broader patient population

Additional presentations at EHA 2026 and ASCO 2026 include abstracts related to ongoing myelofibrosis and AML clinical programs

FOSTER CITY, Calif., May 12, 2026 (GLOBE NEWSWIRE) -- Geron Corporation (Nasdaq: GERN), a commercial-stage biopharmaceutical company aiming to change lives by changing the course of blood cancer, today announced that the first real-world evidence study of RYTELO^® (imetelstat) in patients with lower-risk myelodysplastic syndromes (LR-MDS) will be presented at the European Hematology Association (EHA) 2026 Congress. The retrospective and prospective investigator-sponsored study, conducted at the Moffitt Cancer Center, reported safety and clinical efficacy of imetelstat in advanced, heavily transfusion dependent patients with LR-MDS, including patients with extensive prior therapies and after luspatercept failure. Data from the retrospective portion of the study will be presented at the EHA 2026 Congress.

“Imetelstat has become an important treatment option for patients with lower-risk myelodysplastic syndromes experiencing anemia and red blood cell transfusion burden, particularly in patients previously treated with ESAs or other therapies,” said David A. Sallman, M.D., Associate Member, Malignant Hematology Department, Moffitt Cancer Center. “As treatment sequencing has emerged as an increasing area of focus in LR-MDS, real-world analyses such as this study can help provide additional context on how therapies are being used in routine clinical practice and across more diverse patient populations. We look forward to presenting these data at EHA 2026.”

“This is the first real-world study evaluating imetelstat in lower-risk MDS, and we are encouraged that the efficacy, safety and tolerability observed were generally consistent with findings from the Phase 3 IMerge trial in a broader patient population with a trend towards more optimal management of cytopenias,” said Joseph E. Eid, M.D., Executive Vice President, Research and Development and Chief Medical Officer of Geron. “These findings add to the growing body of evidence supporting the use of imetelstat as a preferred treatment option following prior therapy for patients with lower-risk MDS and significant transfusion burden. We look forward to presenting data from the prospective portion of this study later this year.”

The data, from the retrospective portion of the investigator-sponsored study, evaluated imetelstat in 40 patients with lower-risk MDS treated at the Moffitt Cancer Center in a real-world setting following U.S. Food and Drug Administration (FDA) approval. Patients included in the analysis had advanced, heavily transfusion-dependent disease and extensive prior treatment exposure, including prior luspatercept, erythropoiesis-stimulating agents (ESAs), hypomethylating agents and lenalidomide. With 14-month follow-up, the analysis reported a red blood cell (RBC) transfusion independence rate of 37.5% lasting at least eight weeks (RBC-TI > 8 weeks) with several responses ongoing at the time of analysis and identified potential predictors of response. The safety profile observed in the study was generally consistent with the known safety profile of imetelstat. Cytopenias were reported as the most common Grade 3/4 adverse event. Exploratory analyses also suggested a trend toward improved responses when imetelstat was used within the first three lines of therapy.

Geron will also have additional presentations at the EHA 2026 Congress and the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting, including abstracts related to its ongoing myelofibrosis clinical programs. This includes an updated overall survival analysis in patients with myelofibrosis treated with imetelstat in the Phase 2 IMbark trial compared with real-world data.

Additional Presentations EHA and ASCO include:

EHA 2026 Presentations

Presentation Title	Author	Abstract Number	Presentation Details
Real-world Outcomes of Imetelstat: Interrogating Safety, Efficacy and Predictors of Response in Heavily Pretreated Lower-Risk MDS Patients*	David A. Sallman, M.D.	#PF670	Poster, Jun 12, 18:45-19:45 CEST
Updated Analysis of Overall Survival with Imetelstat in Patients with Relapsed or Refractory Myelofibrosis From IMBark Versus Real-world Data, and Assessment of Real-world Treatment Patterns	Andrew T. Kuykendall, M.D.	#PB3419	Publication-only
Phase 1/1B Trial of Imetelstat and Azacitadine with or without Venetoclax in Relapsed Acute Myeloid Leukemia (IMAGINE Trial)*	Douglas A. Tremblay, M.D.	#PB2719	Publication-only

*Investigator-sponsored Research (ISR)

ASCO 2026 Presentations

Presentation Title	Author	Abstract Number	Presentation Details
Updated analysis of overall survival with imetelstat in relapsed/refractory myelofibrosis versus real-world data, and assessment of real-world treatment patterns	Andrew T. Kuykendall, M.D.	#366	Poster, Mon. June 1, 9:00 am -12:00 pm CDT
Updated protocol: IMproveMF, a Phase 1b trial of imetelstat + ruxolitinib in patients with intermediate-1/2 or high-risk myelofibrosis	John O. Mascarenhas, M.D.	#394b	Poster, Mon. June 1, 9:00 am -12:00 pm CDT

Please see the full presentations for important qualifications and limitations.

About RYTELO (imetelstat)
RYTELO is an oligonucleotide telomerase inhibitor approved in the U.S. for the treatment of adult patients with 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 LR-MDS with transfusion-dependent anemia. We are also conducting a pivotal Phase 3 clinical trial of imetelstat in JAK-inhibitor 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) the potential of real-world analyses to provide additional context on how therapies such as RYTELO are being used in routine clinical practice and across more diverse patient populations; (ii) Geron’s efforts to expand its understanding of RYTELO in clinical practice; (iii) Geron’s expectations for multiple analyses emerging from investigator-sponsored research which will complement clinical trial data and help inform treatment decisions for people living with LR-MDS; (iv) the potential for telomerase inhibition to reduce proliferation and induce death of malignant cells; 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) Geron’s future opportunities and plans, including the uncertainty of the nature of, and the timing and reporting of data emerging from, investigator-sponsored and real-world evidence trials of RYTELO; (b) whether Geron overcomes potential delays and other adverse impacts that may be caused by enrollment, clinical, safety, efficacy, technical, scientific, intellectual property, manufacturing, supply chain, pricing, coverage and reimbursement, market penetration, regulatory and healthcare challenges in order to obtain and maintain the financial resources for and meet expected timelines and planned milestones, including the financial resources necessary to support investigator-sponsored research of RYTELO; (c) Geron’s reliance on investigator-sponsored research, including risks related to Geron’s lack of control over such investigator-sponsored research of RYTELO and the risk that investigator-led clinical trials over which Geron has no control could show marginal efficacy and/or clinically relevant safety concerns that could delay, limit or preclude the further clinical development, marketing approval and/or commercialization of RYTELO in any indication; (d) whether regulatory authorities permit the further development of imetelstat on a timely basis, or at all, without any clinical holds; (e) whether any future safety or efficacy results of RYTELO treatment cause its benefit-risk profile to become unacceptable; (f) whether imetelstat actually demonstrates disease-modifying activity in patients, including transfusion independence in LR-MDS, and the ability to target the malignant stem and progenitor cells of the underlying disease; (g) whether Geron meets its post-marketing requirements and commitments for RYTELO; and (h) whether there are failures or delays in manufacturing or supplying sufficient quantities of RYTELO (imetelstat) or other clinical trial materials that negatively impact the conduct and timing of clinical trials. 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, 2026, 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.

Investor and Media:
Dawn Schottlandt
Senior Vice President, Investor Relations and Corporate Affairs
dschottlandt@geron.com

First Real-World Evidence Study of RYTELO® (imetelstat) in Lower-risk Myelodysplastic Syndromes (LR-MDS) to be Presented at EHA 2026