Trial · NCT03861273
A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B
NCT03861273, Phase 3, Active not recruiting, Pfizer; results first posted 2024-03-27
3 sourcestrials-2026-11-12-0.5.0
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ConductScience Library. A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B. Trials, record NCT03861273. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT03861273
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Trial
As registered on ClinicalTrials.gov, in the graph's capture of the registry.
- Title
- A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B
- NCT number
- NCT03861273
- Status
- Active not recruiting
- Phases
- Phase 3
- Enrollment
- 51 participants, actual
- Lead sponsor
- Pfizer
- Conditions
- Hemophilia B
- Interventions
- PF-06838435/ fidanacogene elaparvovec
- First posted
- 2019-03-04
- Last updated
- 2026-11-04
- Results first posted
- 2024-03-27
- Limitations and caveats
C0371004 lead-in ongoing study: did not involve any investigational intervention; designed to collect bleed, infusion data while participants were on their prophylaxis FIX therapy for a minimum of 6 months; data served as within participant comparison group for C0371002; participant flow and AEs are missing as the study has not concluded yet (some participants in the C0371004 are ongoing and supporting a different study NCT04370054) and data will be provided at conclusion of the lead-in study.
Source ClinicalTrials.gov
Registered outcomes27
Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.
| List | Outcome | Time frame | Description |
|---|---|---|---|
| Primary | Annualized Bleeding Rate (ABR) for Total Bleeds (Treated and Untreated) From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Treated Bleed: An event necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding (protocol definition, unless specifically referring to untreated bleed). Untreated Bleed: A bleeding event not necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | ABR for Treated Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Treated Bleed: An event necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding (protocol definition, unless specifically referring to untreated bleed). This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | Annualized Infusion Rate (AIR) of Exogenous FIX From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | AIR = number of exogenous infusions (for any reason) received during given time period \*365.25/ (Date of last day - date of first day +1) in that time period. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 | Week 12 to Month 15 | The certified central clinical laboratory analyzed the sample by two one-stage assays and a chromogenic assay. The first one-stage assay was performed on BCSXP analyzer with Actin-FSL reagent. The second one-stage assay used the same analyzer but SynthAsil as reagent. Data reported in this Outcome Measure is the geometric mean of all assessments from week 12 to Month 15. |
| Secondary | Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 | Week 12, Week 24, Week 65 | The certified central clinical laboratory analyzed the sample by two one-stage assays and a chromogenic assay. The first one-stage assay was performed on BCSXP analyzer with Actin-FSL reagent. The second one-stage assay used the same analyzer but SynthAsil as reagent. |
| Secondary | Annualized Factor IX (FIX) Consumption From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Annualized FIX consumption was reported by International Units per kilogram (IU/kg). This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. Data reported in this Outcome Measure is average of all assessments from Week 12 to Month 15. |
| Secondary | ABR for Spontaneous Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Spontaneous Bleeds: Bleeding for no apparent/known reason particularly into the joints, muscles, and soft tissues. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | ABR for Traumatic Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Traumatic Bleeds: Bleeding event occurring for an apparent/known reason. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | ABR for Untreated Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Untreated Bleed: A bleeding event not necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
| Secondary | Number of Target Joint Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Target Joint: Defined as a major joint (e.g., hip, elbow, wrist, shoulder, knee, and ankle) into which repeated bleeds occurred (three or more spontaneous bleeds into a single joint within a consecutive 6-month period). A target joint was considered resolved when there were =\<2 bleeds into the joint within a 12-month period. Joint Bleed: A bleeding episode characterized by rapid loss of range of motion as compared with baseline that was associated with any combination of the following: pain or an unusual sensation in the joint, palpable swelling, and warmth of the skin over the joint. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. |
1 to 10 of 27Source ClinicalTrials.gov
See all 27 registered outcomesOutcomes27
Each outcome the trial posted results for, in ClinicalTrials.gov's words.
| Type | Outcome | Time frame | Population | Units | Measured as |
|---|---|---|---|---|---|
| PRIMARY | Annualized Bleeding Rate (ABR) for Total Bleeds (Treated and Untreated) From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Total bleeds per year | MEAN |
| SECONDARY | ABR for Treated Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Treated bleeds per year | MEAN |
| SECONDARY | Annualized Infusion Rate (AIR) of Exogenous FIX From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Exogenous infusions per year | MEAN |
| SECONDARY | Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 | Week 12 to Month 15 | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. The assessments at the visits following participant withdrawal/dropout/FIX prophylaxis resumption were imputed as 1.9%. Here, Number Analyzed signifies number of participants evaluable for specified rows of respective arms. | Percentage of Normal | GEOMETRIC_MEAN |
| SECONDARY | Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 | Week 12, Week 24, Week 65 | Dosed analysis set: participants enrolled in the study who received PF-06838435 infusion. The assessments at the visits following participant withdrawal/dropout/FIX prophylaxis resumption were imputed as 1.9%. Number Analyzed: at each row represents the number of participants with valid FIX:C assessments at the respective time points. All participants reported under 'Number of Participants Analyzed' contributed data to the table; however, may not have evaluable data for every row. | Percentage of Normal | MEAN |
| SECONDARY | Annualized Factor IX (FIX) Consumption From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | IU/kg per year | MEAN |
| SECONDARY | ABR for Spontaneous Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Spontaneous bleeds per year | MEAN |
| SECONDARY | ABR for Traumatic Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Traumatic bleeds per year | MEAN |
| SECONDARY | ABR for Untreated Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Untreated bleeds per year | MEAN |
| SECONDARY | Number of Target Joint Bleeds From Week 12 to Month 15 | Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm) | Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. | Target joint bleeds | MEAN |
1 to 10 of 27Source ClinicalTrials.gov
See all 27 outcomesResults by group36
Each measurement the trial posted, group by group, in the words and numbers it posted.
| Outcome | Group | Category | Value | Spread | Units |
|---|---|---|---|---|---|
| Annualized Bleeding Rate (ABR) for Total Bleeds (Treated and Untreated) From Week 12 to Month 15 | FIX Prophylaxis | 4.43 | 95% Confidence Interval 1.81 to 7.05 | Total bleeds per year | |
| Annualized Bleeding Rate (ABR) for Total Bleeds (Treated and Untreated) From Week 12 to Month 15 | PF-06838435 | 1.30 | 95% Confidence Interval 0.59 to 2.02 | Total bleeds per year | |
| ABR for Treated Bleeds From Week 12 to Month 15 | FIX Prophylaxis | 3.35 | 95% Confidence Interval 1.71 to 4.98 | Treated bleeds per year | |
| ABR for Treated Bleeds From Week 12 to Month 15 | PF-06838435 | 0.73 | 95% Confidence Interval 0.25 to 1.21 | Treated bleeds per year | |
| Annualized Infusion Rate (AIR) of Exogenous FIX From Week 12 to Month 15 | FIX Prophylaxis | 58.83 | Standard Deviation 29.056 | Exogenous infusions per year | |
| Annualized Infusion Rate (AIR) of Exogenous FIX From Week 12 to Month 15 | PF-06838435 | 4.46 | Standard Deviation 10.028 | Exogenous infusions per year | |
| Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 | PF-06838435 | Week 12 to Month 15: One-stage Assay (Actin-FSL Reagent) | 12.62 | Standard Deviation 8.92 | Percentage of Normal |
| Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 | PF-06838435 | Week 12 to Month 15: One-stage Assay (SynthASil Reagent) | 25.90 | Standard Deviation 16.89 | Percentage of Normal |
| Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 | PF-06838435 | Week 12 to Month 15: Chromogenic Assay | 13.49 | Standard Deviation 10.40 | Percentage of Normal |
| Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 | PF-06838435 | Week 12: One-stage Assay (Actin-FSL Reagent) | 13.52 | Standard Deviation 8.134 | Percentage of Normal |
1 to 10 of 36Source ClinicalTrials.gov
See all 36 results by groupParticipant flow12
How many started, completed or left each group, period by period.
| Period | Milestone | Group | Participants | Units counted |
|---|---|---|---|---|
| Screening Phase (3 Weeks) | STARTED | PF-06838435 | 51 | |
| Screening Phase (3 Weeks) | COMPLETED | PF-06838435 | 45 | |
| Screening Phase (3 Weeks) | NOT COMPLETED | PF-06838435 | 6 | |
| Treatment Phase (Day 1) | STARTED | PF-06838435 | 45 | |
| Treatment Phase (Day 1) | COMPLETED | PF-06838435 | 45 | |
| Treatment Phase (Day 1) | NOT COMPLETED | PF-06838435 | 0 | |
| Follow-up Phase (Year 1) | STARTED | PF-06838435 | 45 | |
| Follow-up Phase (Year 1) | COMPLETED | PF-06838435 | 43 | |
| Follow-up Phase (Year 1) | NOT COMPLETED | PF-06838435 | 2 | |
| Long-Term Follow-Up (Year 2 to Year 6) | STARTED | PF-06838435 | 43 |
1 to 10 of 12Source ClinicalTrials.gov
See all 12 participant flowAdverse events31
Each adverse event the trial posted, group by group: the participants affected out of those at risk.
| Type | Event | Organ system | Group | Affected | At risk | Events |
|---|---|---|---|---|---|---|
| other | Abdominal pain | Gastrointestinal disorders | PF-06838435 | 3 | 45 | |
| other | Abdominal pain upper | Gastrointestinal disorders | PF-06838435 | 3 | 45 | |
| other | Hepatic function abnormal | Hepatobiliary disorders | PF-06838435 | 6 | 45 | |
| other | Hepatic steatosis | Hepatobiliary disorders | PF-06838435 | 3 | 45 | |
| other | COVID-19 | Infections and infestations | PF-06838435 | 5 | 45 | |
| other | Nasopharyngitis | Infections and infestations | PF-06838435 | 8 | 45 | |
| other | Upper respiratory tract infection | Infections and infestations | PF-06838435 | 4 | 45 | |
| other | Alanine aminotransferase increased | Investigations | PF-06838435 | 12 | 45 | |
| other | Aspartate aminotransferase increased | Investigations | PF-06838435 | 3 | 45 | |
| other | Hepatic enzyme increased | Investigations | PF-06838435 | 3 | 45 |
1 to 10 of 31Source ClinicalTrials.gov
See all 31 adverse eventsAdverse event totals3
The totals the trial posted for each group.
| Total | Group | Affected | At risk |
|---|---|---|---|
| Total, all-cause mortality | PF-06838435 | 0 | 45 |
| Total, other adverse events | PF-06838435 | 37 | 45 |
| Total, serious adverse events | PF-06838435 | 7 | 45 |
Source ClinicalTrials.gov
Papers2
The papers the trial lists on ClinicalTrials.gov.
Grants0
The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.
None in this release.
Trial comparisons0
Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.
None in this release.
Tests0
The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.
None in this release.
Data dates
The day each source was copied for this release.
Sources 3
- ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
- ClinicalTrials.govNo license stated
- NIH RePORTER's clinical studies and project filesPublic domain
Each source's terms
- ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
- ClinicalTrials.govnone stated
- NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)
ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.
For software
Read this trial from software.
The record and each of its lists are JSON, twenty rows a page. No key.
GET https://conductscience.org/api/trials/v1/NCT03861273
GET https://conductscience.org/api/trials/v1/NCT03861273/registered?page=2