• ClinicalTrials.gov Identifier: NCT03369444
• A Phase I/II, Open Label, Ascending Single Dose Safety Study

• Terminated due to challenges during the COVID-19 pandemic and a change in requirements of data to be submitted for marketing authorization ^*
• Last Update Posted: December 2, 2022 ^*

• Adults males, ≥ 18 years of age
• Severe FIX deficiency with plasma FIX activity of<1% of normal o rmoderately severe FIX deficiency with plasma FIX activity level ≥1% and ≤2%
• At least 150 exposure days to FIX concentrates

• Patients at high risk of thromboembolic events

AAVS3, Mammalian cell manufacturing (iCELLis^®) ¹⁷

FIX-Padua ¹⁶

• New small liver‐ specific promoter referred to as FRE1 ¹⁶ or HLP2 ⁴³
• An optimized ⁴⁴ truncated FIX intron 1 ⁴³

Systemic ²⁹

Initially, dose levels in the 4 dose cohorts were reported here ¹⁷ as follows: 

• Co. 1: 4.5e11 (2)
• Co. 2: 7.5e11 (2)
• Co. 3: 9.5e11 (4)
• Co. 4: 1.5e12 (2)

Subsequently, dose levels were adjusted according to changed vector genome titer assay and reference standard ⁴¹ as follows :

• Co. 1: 3.84e11 (2)
• Co. 2: 6.4e11 (2)
• Co. 3: 8.32xe11 (4)
• Co. 4: 1.28xe12 (2)

Initially, follow-up times were reported here ¹⁷ as follows: 

• Co. 1: 66-78 weeks
• Co. 2: 26 weeks
• Co. 3: 3  weeks
• Co. 4: 26weeks

Subsequently, here ⁴¹ as follows:

• Co. 1 - Co. 4: ≥ 16 weeks

OS ¹⁶, FIX:C levels assessed by chromogenic assay were 2-fold lower ¹⁶

• Steady state FIX:C levels in Co. 1 were 42.5 ± 6 % using an OS clotting assay ¹⁶

Following data regarding the mean FIX activity at W3 and W104 were taken from here ⁴⁰ and summarized as follows:

• At W3, FIX activity levels in Co. 1- Co. 4 were in the range of 24% to 168 %
• Pts. in Co. 1 (4.5e11vg/Kg), have stable, therapeutic, FIX activity levels through W104

Not reported

Co. 1 (low dose): no spontaneous bleeding episodes in 2/2 pts. ¹⁶

No need of FIX concentrate infusions over 12 months follow up following gene transfer¹⁶

No evidence of infusion-related reactions ^{17, 41}

• No serious AEs following gene transfer ¹⁶
• The most common drug related SAE was transient transaminitis (in 4 pts.) requiring supplemental immunosuppression ⁴⁰
• Observed FIX activities levels above 150% were individually assessed for risk of thrombosis, and one patient is being treated with DOACs ⁴¹

Not reported

• Co. 1: Liver enzymes within the normal range ¹⁶
• Co. 1-4: Transaminitis in 2 pts. (magnitude and cohort not reported) ¹⁷

• Co. 1: Liver enzymes within the normal range ¹⁶
• Co. 1-4: Transaminitis in 2 patients (magnitude and cohort not reported) ¹⁷

Not reported ¹⁶

• Co. 1: Prophylactic steroids W4-12 ¹⁶
• Co. 2-4: Prophylactic steroids + TAC ¹⁷
• Not reported ¹⁶

• Co. 1: No ¹⁶ 
• Co. 1-4: Yes, in 2 pts. (magnitude and cohort not reported) transaminitis associated with decreased FIX expression ¹⁷

Not reported

  *   ClinicalTrials.gov
16. Chowdary, P., et al., FLT180a: Next Generation AAV Vector for Haemophilia B - Long Term, Follow- up and In- depth Analysis of Transgenic
       FIX Using One- stage, Chromogenic and Global Assays. Res Pract Thromb Haemostasis, 2019. 3(S1): p. 307.ISTH Academy
17. Freeline. Corporate presentation. 2020 [cited 2020 06 May]; Available from: PowerPoint Presentation (azureedge.net)
29. Manno, C.S., et al., AAV-mediated factor IX gene transfer to skeletal muscle in patients with severe hemophilia B. Blood, 2003. 101(8): p. 2963-72.
       AAV-mediated factor IX gene transfer to skeletal muscle in patients with severe hemophilia B - PubMed (nih.gov)
40. Chowdary, P., et al., A Novel Adeno Associated Virus (AAV) Gene Therapy (FLT180a) Achieves Normal FIX Activity Levels in Severe Hemophilia B
      (HB) Patients (B-AMAZE Study). ISTH 2020 Congress, 2020. Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia Gene Therapy.
      A Novel Adeno Associated Virus (AAV) Gene Therapy (FLT180a) Achieves Normal FIX Activity Levels in Severe Hemophilia B (HB) Patients
      (B-AMAZE Study) - ISTH Congress Abstracts
41. Chowdary, P., et al., Factor IX Expression within the Normal Range Prevents Spontaneous Bleeds Requiring Treatment Following FLT180a Gene
       Therapy in Patients with Severe Hemophilia B: Long-Term Follow-up Study of the B-Amaze Program. ASH Annual Meeting 2021, 2021.
       Oral and Poster Abstracts. Factor IX Expression within the Normal Range Prevents Spontaneous Bleeds Requiring Treatment Following FLT180a
       Gene Therapy in Patients with Severe Hemophilia B: Long-Term Follow-up Study of the B-Amaze Program - ScienceDirect
43. Peyvandi, F. and I. Garagiola, Clinical advances in gene therapy updates on clinical trials of gene therapy in haemophilia. Haemophilia,
      2019. 25(5): p. 738-746.Clinical advances in gene therapy updates on clinical trials of gene therapy in haemophilia - PubMed (nih.gov)
44. Freeline. B-AMAZE Phase 1/2 Study of FLT180a in Haemophilia B. 2020; Available from: PowerPoint Presentation (freeline.life)

AAV, Adeno-associated virus; AEs, Adverse events; ABR, Annualized bleeding rate; AEs: adverse events; AIR, Annualized FVIII/FIX infusion rate; ALT, alanine aminotransferase; AST, aspartate aminotransferase; CH, Chromogenic Assay; Co., cohort; DOACs, Direct oral anticoagulants; D, days; EDs, exposure days; FIX, factor IX; FIX-Padua, gain of function FIX variant; FVIII, factor VIII; gc, genome copies; HEK cells, human embryonic kidney cells; IQR, interquartile range; IRR, Infusion-related reaction; NAbs, neutralizing antibodies; OS, One-stage clotting assay; Pop., population; pt., patient/participant; pts., patients/participants; P1, Participant 1; PI, phase I; PBGD, porphobilinogen deaminase; PBMC, peripheral blood mononuclear cells; SAEs, serious adverse events; SFU, spot-forming units; TAC, tacrolimus; ULN, upper limit of normal; VCN, vector copy number; vg, vector genomes; W, weeks; WT, wild type; Y, year