A Phase 3 interventional study of Imetelstat and Best Available Therapy (BAT) in Myelofibrosis, sponsored by Geron Corporation. Active, not recruiting at 144 sites in 26 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-08.
Sponsored by Geron Corporation · Phase 3, Interventional, and Treatment
The purpose of the study is to evaluate the overall survival of participants treated with imetelstat compared to best available therapy with intermediate-2 or high-risk Myelofibrosis (MF) who are relapsed/refractory (R/R) to Janus Kinase (JAK)-Inhibitor treatment.
This is a multicenter study with 2 arms, and will include 3 phases: a) screening phase of up to 28 days before randomization during which participants will complete a 14-day washout period from all prior therapies including JAK-inhibitor treatment, and the participant's eligibility will be reviewed; b) treatment phase, from randomization until study treatment (imetelstat or BAT) discontinuation; and c) post treatment follow-up phase, that begins when the participant discontinues treatment, and will continue until death, lost to follow-up, withdrawal of consent, or study end, whichever occurs first. Participants will be randomized (2:1) into 2 Arms (Arm A will receive imetelstat and Arm B will receive BAT).
Participants who meet progressive disease criteria and discontinue BAT, may crossover to receive imetelstat treatment after sponsor's approval.
625 studies on the registry are indexed under Primary Myelofibrosis; 124 are open to participants now.
This study's enrollment of 327 is above the median of 43 across 489 interventional studies indexed under Primary Myelofibrosis.
Browse Primary Myelofibrosis studies →Geron Corporation is the lead sponsor of 16 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
to JAK-inhibitor treatment as defined in either inclusion (i), (ii) or (iii) and not eligible for stem cell transplantation (ASCT) at screening:
(i) Treatment with JAK-inhibitor for >= 6 months duration, including at least 2 months at an optimal dose as assessed by the investigator for that participant and at least one of the following:
(iii) Following maximum tolerated doses of JAK inhibitor therapy for ≥3 months duration, having documented relapsed disease defined as either
Increase in spleen size by palpation, CT, or ultrasound
AND not a candidate for further JAK inhibitor at screening per investigator.
Exclusion Criteria:
Diagnosis or treatment for other than MF except:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive imetelstat sodium at 9.4 mg/kg intravenous (IV) every 21 days (±3 days), until disease progression or unacceptable toxicity, treatment discontinuation or study end.
Drug: Imetelstat
Participants will receive BAT (investigator-selected non-JAK-inhibitor treatment), until disease progression or unacceptable toxicity, treatment discontinuation or study end. Participants on BAT who meet protocol-defined criteria for progressive disease may crossover to receive imetelstat treatment after sponsor's approval.
Drug: Best Available Therapy (BAT)
Imetelstat sodium will be given intravenously at 9.4 mg/kg every 21 days, until disease progression or unacceptable toxicity, treatment discontinuation or study end.
Also known as: GRN163L
Non-JAK-inhibitor treatment will be given, which may include but is not limited to hydroxyurea, thalidomide or an analog of thalidomide, interferon, danazol, hypomethylating agents, chemotherapy or radiotherapy.
Overall survival (OS)
Overall survival is defined as the time interval from randomization date to date of death from any cause.
Time frame: Baseline (Day 1) until End of Study (EOS) (approximately 3 years )]
Symptom response rate
The proportion of participants achieving a ≥50% reduction in Total Symptom Score (TSS) measured at Week 24 compared to baseline
Time frame: Baseline (Day 1), and at Week 24
Progression-free survival
Progression-free survival is defined as the time interval from randomization date to the first date of disease progression (worsening splenomegaly or leukemic transformation per 2013 International Working Group - Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria) or death from any cause, whichever occurs first.
Time frame: Baseline (Day 1) until End of Study (EOS) (approximately 3 years)
Spleen response rate
The proportion of participants who achieve a reduction in spleen volume of ≥ 35% from baseline at Week 24.
Time frame: Baseline (Day 1), and at Week 24
Complete remission (CR), partial remission (PR), clinical improvement (CI), spleen response, symptoms response, and anemia response per modified 2013 IWG-MRT criteria
The proportion of participants achieving CR or PR, CI, spleen response, symptom response, and anemia response per modified 2013 IWG-MRT criteria.
Time frame: Baseline (Day 1) until End of Treatment (approximately 3 years)
Reduction in the degree of bone marrow fibrosis
Reduction in the degree of bone marrow fibrosis will be assessed.
Time frame: Baseline (Day 1) until End of Treatment (approximately 3 years)
Number of Participants with Adverse Events
Safety will be assessed based on the incidence and severity (according to the Common Terminology Criteria for Adverse Events) of treatment emergent adverse events from the time of randomization until 30 days after completion of treatment
Time frame: Screening (Day -28 to -1) until End of Study (approximately 3 years)
Assessment of Cmax
Maximum Observed Plasma Concentration (Cmax).
Time frame: Day 1 of all cycles (each cycle is 21 days)
Assessment of Tmax
Time to reach the maximum observed plasma concentration
Time frame: Day 1 of all cycles (each cycle is 21 days)
Assessment of t1/2
Elimination half-life.
Time frame: Day 1 of all cycles (each cycle is 21 days)
Assessment of AUC
Area under the drug concentration-plasma time curve (AUC) from time zero to last measurable concentration
Time frame: Day 1 of all cycles (each cycle is 21 days)
European Organization for Research and Treatment of Cancer Quality-of-Life-Questionnaire-Core-30 (EORTC QLQ-C30) scores
Patient-reported outcomes including health-related quality of life, pain, and overall change in participant's health will be assessed using the EORTC QLQ-C30. The EORTC QLQ-C30 includes 30 items resulting in 5 functional scales (physical functioning, role functioning, emotional functioning, cognitive functioning, and social functioning), 1 Global Health Status scale, 3 symptom scales (fatigue, nausea and vomiting, and pain), and 6 single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Scores are transformed to a 0 to 100 scale. Higher scores indicated worse outcome.
Time frame: Baseline to End of Study (approximately 3 years)
EuroQol-EQ-5D (EQ-5D-5L) questionnaire scores
EQ-5D-5L is a 5 item questionnaire that assesses 5 domains including mobility, self-care, usual activities, pain/discomfort and anxiety/depression plus a visual analog scale rating "health today" with anchors ranging from 0 (worst imaginable health state) to 100 (best imaginable health state).
Time frame: Baseline to End of Study (approximately 3 years)
Showing the first 100 of 144 sites across 26 countries. Choose a country and city above to see the rest.
Started Apr 2021 (actual). Primary completion is estimated for Jun 2028, 86 months after the start.
Of 22 phase 3 interventional studies under Primary Myelofibrosis, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 30 and three quarters within 68. This study's planned 86 months is above that.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Imetelstat
Geron Corporation