A Phase 1 interventional study of PRT12396 in Polycythemia Vera (PV), Myelofibrosis (MF) and Myeloproliferative Neoplasms (MPNs), sponsored by Prelude Therapeutics Incorporated. Recruiting at 22 sites in 5 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Prelude Therapeutics Incorporated · Phase 1, Interventional, and Treatment
This is a first-in-human, open-label, multi-center Phase 1 study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of PRT12396 in participants with high-risk polycythemia vera (PV) and myelofibrosis (MF), and to determine the maximum tolerated dose (MTD) and recommended dose(s) for expansion (RDE[s]). The study consists of a dose-escalation phase followed by a dose-expansion phase to further evaluate selected dose level(s).
This first-in-human, open-label, multi-center Phase 1 study is designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of PRT12396 in participants with high-risk polycythemia vera (PV) and myelofibrosis (MF). Eligible MF populations include participants with intermediate-1, intermediate-2, or high-risk primary MF, as well as post-polycythemia vera MF or post-essential thrombocythemia MF, with evidence of disease burden based on splenomegaly.
The study is conducted in two parts:
Part 1 (dose escalation) evaluates escalating oral doses of PRT12396 to evaluate safety and tolerability and to determine the maximum tolerated dose (MTD) and recommended dose(s) for expansion (RDE[s]).
Part 2 (dose expansion) enrolls additional participants at selected dose level(s) to further characterize the safety, tolerability, pharmacokinetics, and preliminary efficacy of PRT12396 in the PV and MF populations.
Approximately up to 100 participants are planned for enrollment across both parts of the study.
278 studies on the registry are indexed under Polycythemia Vera; 53 are open to participants now.
This study's planned enrollment of 100 is above the median of 52 across 204 interventional studies indexed under Polycythemia Vera.
Browse Polycythemia Vera studies →Prelude Therapeutics Incorporated is the lead sponsor of 2 studies on the registry; 2 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.
Exclusion Criteria:
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.
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.
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.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
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.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
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.
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.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
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.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
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.
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.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants with myelofibrosis receive PRT12396, an investigational oral capsule, administered twice daily. The study includes a dose-escalation followed by dose-expansion at the recommended dose for expansion (RDE)
Drug: PRT12396
Participants with polycythemia vera receive PRT12396, an investigational oral capsule, administered twice daily. The study includes a dose-escalation followed by dose-expansion at the recommended dose for expansion (RDE)
Drug: PRT12396
PRT12396 is an investigational oral capsule administered twice daily at the assigned dose level or RDE. Capsules are swallowed whole with water and may be taken one hour before or two hours after meals.
Dose limiting toxicity (DLT) of PRT12396
Incidence of dose limiting toxicities, defined according to protocol-specified criteria
Time frame: Through cycle 1 (4 weeks)
Incidence and severity of Adverse events
Incidence and severity of treatment-emergent adverse events (AEs), graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), Version 6.0
Time frame: Through study completion, an average of 2 years
Adverse Events Leading to Dose Modifications or Discontinuation
Incidence of AEs leading to dose reductions, dose interruptions, treatment discontinuations, and clinically significant laboratory abnormalities
Time frame: Through study completion, an average of 2 years
Maximum tolerated dose (MTD) and Recommended Dose(s) for Expansion (RDE[s]) of PRT12396
Determination of the maximum tolerated dose (MTD) and recommended dose(s) for expansion (RDE\[s\]) based on evaluation of DLTs, safety, and tolerability data
Time frame: Through study completion, an average of 2 years
Hematologic Response Rate (PV)
Proportion of participants with polycythemia vera (PV) achieving best overall hematologic response (complete hematologic response or partial hematologic response) from the overall response assessments by Investigator
Time frame: Through study completion, an average of 2 years
Duration of Hematologic Response (PV)
Duration of hematologic response in PV participants, defined as the time from first documented response (best overall hematologic response) to disease progression or death, whichever comes first
Time frame: Through study completion, an average of 2 years
Hematocrit Control Without Phlebotomy Requirements (PV)
Proportion of PV participants achieving and maintaining hematocrit control without phlebotomy, time to first phlebotomy, and frequency of phlebotomy
Time frame: Through study completion, an average of 2 years
Spleen Response (MF)
Assessment of spleen response including proportion achieving protocol-specified reduction in spleen volume, time to spleen response, duration of spleen response, and reduction in palpable spleen length
Time frame: Through study completion, an average of 2 years
Change from Baseline in Hemoglobin (MF)
Change from baseline in hemoglobin levels in MF participants
Time frame: Through study completion, an average of 2 years
Change from Baseline in Platelet Count (MF)
Change from baseline in platelet count in MF participants
Time frame: Through study completion, an average of 2 years
Change from Baseline in Absolute Neutrophil Count (MF)
Change from baseline in absolute neutrophil count in MF participants
Time frame: Through study completion, an average of 2 years
Transfusion Independence (MF)
Proportion achieving transfusion independence and duration of transfusion independence as defined by protocol criteria
Time frame: Through study completion, an average of 2 years
Maximum Observed Plasma Concentration (Cmax)
Maximum observed plasma concentration will be calculated using non-compartmental analysis
Time frame: Up to Cycle 4 Day 1 (each cycle is 4 weeks)
Time To Maximum Concentration (Tmax)
Time to maximum concentration will be calculated using non-compartmental analysis
Time frame: Up to Cycle 4 Day 1 (each cycle is 4 weeks)
Area under the plasma concentration versus time curve (AUC)
Area under the plasma concentration-time curve will be calculated using non-compartmental analysis
Time frame: Up to Cycle 4 Day 1 (each cycle is 4 weeks)
Terminal Elimination Half-life (T1/2)
Terminal elimination half-life will be calculated using non-compartmental analysis
Time frame: Cycle 1 Day 1
Steady State Trough Concentrations
Steady state trough concentrations will be calculated using non-compartmental analysis
Time frame: Up to Cycle 4 Day 1 (each cycle is 4 weeks)
Clearance
Clearance will be calculated using non-compartmental analysis
Time frame: Cycle 1 Day 1
Accumulation
Accumulation will be calculated using non-compartmental analysis
Time frame: Up to Cycle 4 Day 1 (each cycle is 4 weeks)
Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-SAF TSS)
Patient-reported outcomes assessed using the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-SAF TSS), evaluated as change from baseline at protocol-specified time points. The MPN SAF TSS is a validated questionnaire in which individual symptoms are scored using a numeric rating scale ranging from 0 to 10, with 0 indicating no symptoms and 10 indicating the worst imaginable symptoms; higher scores indicate greater symptom severity.
Time frame: Through study completion, an average of 2 years
Patient Global Impression of Change (PGI-C)
Participant reported outcomes assessed using the Patient Global Impression of Change (PGI-C), evaluated at protocol-specified time points. The PGI C is a global assessment scale in which participants rate their overall change in condition since baseline using a 7 point ordinal scale ranging from "very much improved" to "very much worse," with lower scores indicating improvement and higher scores indicating worsening of symptoms.
Time frame: Through study completion, an average of 2 years
Started Apr 2026 (actual). Primary completion is estimated for Apr 2028, 24 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Prelude Therapeutics Incorporated