Long-term Safety and Efficacy Study and Dose-Escalation Substudy of PF 06838435 in Individuals With Hemophilia B

  • End date
    Sep 2, 2028
  • participants needed
  • sponsor
Updated on 10 May 2022


Long-term safety and efficacy follow-up for participants with Hemophilia B who were previously treated in the C0371005 (formerly SPK-9001-101) study, and a dose-escalation sub-study evaluating safety, tolerability, and kinetics of a higher dose with long-term safety and efficacy follow-up. Participants in the substudy do not need to have participated in C0371005.


Evaluation of the long-term level of persistence and potential late or delayed adverse events associated with PF-06838435 (formerly SPK-9001), assessment of the durability of the transgene expression, and determination of the effects of PF-06838435 on clinical outcomes in individuals who have previously received a single administration of PF-06838435 in the C0371005 study. Amendment 2 of this study incorporates a dose-escalation substudy to evaluate the safety, tolerability, and kinetics of a single IV infusion of PF-06838435 at a higher dose than that used in the C0371005 study. The dose-escalation participants will also be followed for long-term safety and efficacy.

Condition Hemophilia B
Treatment SPK-9001, PF-06838435 (formerly SPK-9001)
Clinical Study IdentifierNCT03307980
Last Modified on10 May 2022


Yes No Not Sure

Inclusion Criteria

Able to provide informed consent and comply with requirements of the study
Males age 18 to 65 years with confirmed diagnosis of hemophilia B (≤2 IU/dL or ≤2%
endogenous factor IX)
Received ≥50 exposure days to factor IX products
No measurable factor IX inhibitor as assessed by the central laboratory and have no
prior history of inhibitors to factor IX protein
Agree to refrain from donating sperm and either abstain from intercourse or use
reliable barrier contraception until 3 consecutive semen samples are negative for
vector sequences

Exclusion Criteria

Evidence of active hepatitis B or C
Currently on antiviral therapy for hepatitis B or C
Have significant underlying liver disease
Any concurrent clinically significant major disease or condition
Serological evidence _of HIV-1 or HIV-2 with CD4 counts ≤200/mm3 (_ participants who
Unable or unwilling to comply with the study procedures
are HIV+ and stable with CD4 count >200/mm3 and undetectable viral load are eligible
to enroll)
Neutralizing antibody titers to the capsid portion of PF-06838435 above the
established threshold
Sensitivity to heparin or heparin induced thrombocytopenia; sensitivity to any of the
study interventions, or components thereof, or drug or other allergy
Previously dosed in a gene therapy research trial at any time or in an interventional
clinical study within 3 months of screening visit
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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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