New RNA drug aims to reduce blood removal in polycythemia vera patients

NCT ID NCT05499013

Disease control Sponsor: Silence Therapeutics plc Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study tests a new drug called SLN124 in 69 adults with polycythemia vera, a condition where the body makes too many red blood cells. The drug works by blocking a protein that controls iron use, which may lower red blood cell production and reduce the need for regular blood removal (phlebotomy). The trial has two phases: first, an open-label dose-finding part, then a randomized double-blind phase where some patients get the drug and others get a placebo.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance: SLN124 (a small interfering RNA drug that targets a protein involved in iron regulation)
What this could lead to: If it works, this could reduce the need for frequent blood removal (phlebotomy) and help manage polycythemia vera more effectively.
What could go wrong: This is an early-phase trial with only 69 participants, so results may not apply to everyone. The drug may cause side effects or fail to show clear benefit.

Why investors are watching

Silence Therapeutics is testing SLN124, an experimental drug for polycythemia vera, a blood disorder where the body makes too many red blood cells. The trial combines an early safety phase with a later randomized, placebo-controlled phase, and results will show whether the drug works and is safe. For a micro-cap company with few products, this readout is a major event because it could validate its main pipeline asset.

If it works: A positive result could show SLN124 controls the disease better than placebo, giving Silence a viable product candidate and a path toward regulatory approval. That outcome would strengthen the company's position and attract partnership interest.

If it fails: The drug may fail to show a meaningful benefit or cause safety problems, which would set the program back. Trials at this stage often fail, and a negative readout could leave the company without a clear lead candidate.

AI-written from the trial record. Speculative, and not investment advice.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 1/2

Runs two stages together: safety and dose first, then whether the treatment works.

Participants

69 people

The number who actually took part.

Started

Jan 2023

Expected to finish

Mar 2030

An estimate. End dates often move.

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Phase 1 and Phase 2 Inclusion Criteria: * Male and female patients aged 18 years or older. * A confirmed diagnosis of PV according to the revised 2016 World Health Organization criteria: * Suitable phlebotomy history * Must agree to adhere to appropriate contraception requirements * Patients who are not receiving cytoreductive therapy must have been discontinued from any prior cytoreductive therapy for at least 24 weeks before dosing and have recovered from any adverse events due to cytoreductive therapy. * Patients receiving cytoreductive therapy with hydroxyurea, interferon, busulfan or ruxolitinib must have received a stable dose of cytoreductive therapy for at least 12 weeks before dosing and with no planned change in dose. * Patients must have had a dermatological examination within 28 weeks prior to dosing. * Must have an Eastern Cooperative Oncology Group score of 0, 1, or 2. Exclusion Criteria: Phase 1 and Phase 2 * Drug intolerance: 1. History of intolerance to oligonucleotides, or GalNAc, or any component of SLN124. 2. History of intolerance to s.c. injections. * Clinically significant thrombosis (e.g., deep vein thrombosis or splenic vein thrombosis) within 12 weeks of screening. * History of major bleeding events and/or a requirement for blood transfusion therapy owing to bleeding in the last 6 months prior to screening. * Meets the criteria for post-PV myelofibrosis as defined by the International Working Group-Myeloproliferative Neoplasms Research and Treatment * Any investigational drug less than 6 weeks prior to the first dose of study drug or not recovered from effects of prior administration of any investigational agent. * Any investigational or marketed product using GalNAc targeting less than 48 weeks prior to administration of any investigational agent (excludes patients with PV who participated in Phase 1 of this study). * Clinically significant co-morbidities * Biochemical and hematological parameters: 1. Biochemical evidence of significant liver disease during screening 2. Phase 1: Hematological parameters at screening as follows: platelets \> 1,000,000/µL; or white blood cell (WBC) count \> 25,000/µL; or peripheral blasts \> 1%. b. Phase 2: Hematological parameters at screening as follows: platelets \> 1,000,000/µL; or WBC count \> 30,000/µL; or peripheral blasts \> 1%.

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Conditions

The condition(s) this trial relates to.

acquired polycythemia vera

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Polycythemia vera

Contacts and locations

Locations

Linear Clinical Research

Nedlands, Australia
Research Site

Hammond, Louisiana, 70403, United States
Research Site

Buffalo, New York, 14203, United States
Research Site

New York, New York, 10029, United States
Research Site

Columbus, Ohio, 43210, United States
Research Site

Huntsville, Texas, 77340, United States
Research Site

Benowa, Australia
Research Site

Hobart, Australia
Research Site

Kurralta Park, Australia
Research Site

Melbourne, Australia
Research Site

Richmond, Australia
Research Site

Plovdiv, Bulgaria
Research Site

Toronto, Canada
Research Site

Freiburg im Breisgau, Germany
Research Site

Hanover, Germany
Research Site

Alessandria, Italy
Research Site

Meldola, Italy
Research Site

Johor Bahru, Malaysia
Research Site

Kuala Terengganu, Malaysia
Research Site

Kuantan, Malaysia
Research Site

Kuching, Malaysia
Research Site

Gdansk, Poland
Research Site

Katowice, Poland
Research Site

Lublin, Poland
Research Site

Barcelona, Spain
Research Site

Madrid, Spain
Research Site 2

Melbourne, Australia
Research Site 2

Plovdiv, Bulgaria

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