A Study to Investigate the Safety and Effectiveness of a Coagulation Factor IX Gene Insertion Therapy (REGV131-LNP1265) in Pediatric, Adolescent and Adult Participants With Hemophilia B

Condition(s) studied

Investigational drug(s) / intervention(s)

REGV131: Administered per the protocol before LNP1265

LNP1265: Administered per the protocol following REGV131

Study summary

Participants in this study have a genetic mutation, specifically in the coagulation (blood clotting) Factor 9 gene that causes severe or moderately severe hemophilia B. This study is researching an experimental gene insertion therapy (the adding of a gene into your DNA) called REGV131-LNP1265, also called the "study drug". Gene insertion therapy aims to teach the body how to produce clotting factor long-term, without the need for factor replacement therapy.

The main aim of this study is to find a safe and well-tolerated dose of the study drug by checking the side effects that may happen from taking it, both in the near term and over time.

The study is looking at several other research questions including:

* How much study drug is in the blood at different times
* Whether the body makes antibodies against parts of the study drug, which could make the drug less effective or could lead to side effects. Antibodies are proteins produced by the body's immune system in response to a foreign substance
* Whether the body makes antibodies against the clotting factor replacement therapy
* How often factor replacement therapy is needed, both on a regular basis for prevention of bleeding, and as needed to treat bleeding events (and it if changes after taking study drug)
* Whether there is a difference in 2 different methods for measuring Factor 9 activity in the blood

Eligibility

Primary outcome measure(s)

• Occurrence of Treatment-Emergent Adverse Events (TEAEs) — Up to 2 Years
  Part 1, 2B, and 2C
• Severity of TEAEs — Up to 2 Years
  Part 1, 2B, and 2C
• Coagulation Factor IX (FIX) functional activity measured using the chromogenic substrate assay — Up to 2 Years
  Part 1
• Change in FIX functional activity in plasma, measured using the chromogenic substrate assay — Up to 2 Years
  Part 2A, 2B, and 2C
• Annualized Bleeding Rate (ABR) following sustained FIX functional activity among participants receiving the RDE — Up to 2 Years
  Part 2A, 2B, and 2C
• Occurrence of Serious Adverse Events (SAEs) — Through Long Term Follow Up (LTFU), Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C
• Severity of SAEs — Through LTFU, Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C
• Occurrence of Adverse Event of Special Interests (AESIs) — Through LTFU, Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C
• Severity of AESIs — Through LTFU, Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C
• Occurrence of clinically meaningful Adverse Events (AEs) — Through LTFU, Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C
• Severity of clinically meaningful AEs — Through LTFU, Up to 15 Years
  LTFU Period for Part 1, 2A, 2B, and 2C

Trial sites (49)

+ 9 more sites — see the full list on the official registry below.

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