Summary Information For: AAVS3, FIX-Padua, FLT180a, NCT03369444
AAVS3, FIX-Padua, FLT180a, NCT03369444
Haemophilia B
University College, London
General Study Information
  • ClinicalTrials.gov Identifier: NCT033694441
  • 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 authorization1
  • Last Update Posted: 2022-12-021
  • 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
  • Further details concerning the exclusion of patients from treatment were published here2, as follows:
    • Liver dysfunction in 1 patient
    • Presence or history of a factor IX inhibitor in 2 patients
    • Lack of a negative result on screening for AAVS3 neutralizing antibodies in 2 patients
    • Withdrawal from participation in the trial in 1 patient, and early termination of the trial in 2 patients
    • One patient had two reasons for exclusion, as follows:
      • A history of a FIX inhibitor and
      • Lack of a negative result on screening
        for AAVS3 neutralizing antibodies

Data regarding the serotype and manufacturing platform were collected form here2 [Supplementary Appendix] and are summarized as follows:

  • AAVS3 capsid that consists of a VP1u portion from AAV8 with the remainder (i.e. VP2u and VP3) from AAV3B
  • Mammalian cell production system (HEK293T cell line)

FIX-Padua2-3

New small liverÔÇÉ specific promoter referred to as FRE12 [Supplementary Appendix], 3 or HLP24
The following information regarding the FRE1 promoter was reported here2 and is summarized as shown bellow:  

  • The FRE1 promoter is a transcriptional control unit that consists of truncated elements of the
    • liver-specific human alpha-1 antitrypsin (hAAT) promoter and
    • human apolipoprotein E (ApoE) hepatic control region enhancer.
  • The FIX Padua variant-encoding expression cassette2 [Supplementary Appendix] contains the
    • Wild-type sequence of hFIX in exon 1 and the 5' portion of exon 2
    • These exons flank a truncated version of the intron natively present in that position
    • The 3' portion of exon 2 and the remaining exons are codon optimized and devoid of CpG dinucleotides
  • The expression cassette contains also a bovine growth factor polyadenylation signal2 [Supplementary Appendix]

Single IV infusion into a peripheral vein2 [Supplementary Appendix]

Dose levels were adjusted according to a changed vector genome titer assay and reference standard25 as follows :

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

Details on follow-up times were published here2 as follows:

  • The primary end points were safety and efficacy, as assessed by FIX levels at week 26
  • After 26 weeks, patients were enrolled in a long-term follow-up study

OS2-3, FIX:C levels assessed by chromogenic assay were 2-fold lower3

Efficacy details
  • Steady state FIX:C levels in Co. 1 were 42.5 ± 6 % using an OS clotting assay3
  • Following data regarding the mean FIX activity at W3 and W104 were taken from here6 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

Mean FIX Activities Over Time as Reported here6

Cohort

N

week 3

week 26

week 52

week 78

Co. 1 (4.5e11 vg/kg)

2

24.5%

40% 

37.5 %

43.5 % 

Co. 2 (7.5e11 vg/kg)

2

25.5%

32.0%

31.0% 

-

Co. 3 (9.5e11 vg/kg)

4

100.5

98.0 %

-

-

Co. 4 (1.5e12 vg/kg)

2

130 %

160 %

-

-


Patient-specific FIX levels at early time points after gene therapy were reported here2 and are summarized as follows:

  • Co. 2 (6.4e11 vg/kg), prophylactic immunosuppression with prednisolone:
    • P4 had an initial steady increase in the FIX level to 47% by week 5
    • FIX levels in P4 decreased to less than 2% at month 11
  • Co. 3 (8.32e11 vg/kg), prophylactic immunosuppression with glucocorticoids and tacrolimus:
    • FIX levels in P7 reached 228% at week 4 with steady levels with a mean of 52.3±2.9% for months 12 through 22
    • P8, P9, and P10 all had FIX levels of more than 150% by week 4 or 5
    • High FIX levels P8, P9, and P10 were sustained throughout the 26-week trial period
  • Co. 4 (1.28e12 vg/kg), prophylactic immunosuppression with prednisolone:
    • FIX levels rose steadily in P3 and reached 167% by week 5
    • FIX levels in P6 increased into the normal range approximately 1 week after infusion and reached 310% at week 4
    • P6 required anticoagulation treatment with Apixaban for approx. 7 months

Further data on FIX levels per patient at week 26 and from month 12 trough the last follow-up after gene therapy have been published here2 and are summarized as follows:

FIX level (%) per patient at the indicated time point after gene therapy as shown in Table 12 and Table S12

Vector dose (vg/kg)

3.84e11 vg/kg

1.28e12 vg/kg

6.40e11 vg/kg

1.28e12 vg/kg

8.32e11 vg/kg

Patient Nr.

1

2

3

4

5

6

7

8

9

10

Week 26, %

44

46

71

7

64

280

53

180

190

143

From Month 12 through last follow-up, mean % (SD)

47.8
(3.95)

38.2
(3.63)

80.1
(8.67)

10.53
(6.78)a

61.0
(4.24)b

279
(26.87)b

52.3
(2.91)

63.8
(19.67)

40.9
(4.16)

28.2
(5.34)

Last Follow up, % (month)

51 (M42)

43 (M36)

78 (M30)

9d (M30)

57 (M24)

260 (M24)

58 (M22)

59 (M21)

36 (M19)

23 (M18)

                   aPatient 4 resumed FIX prophylaxis in Month 13
                   bLess than 5 values available for calculation

According to Figure 22, the peak response in FIX activity was achieved around 5 to 10 weeks following gene therapy.

Follow-up data on annualized bleeding rates per patient have been published here2 and are summarized as follows:

Effect of Gene Therapy on Annualized Bleeding Rate as shown in Table S12

Vector dose (vg/kg)

3.84e11 vg/kg

1.28e12 vg/kg

6.40e11 vg/kg

1.28e12 vg/kg

8.32e11 vg/kg

 

Patient Nr.

1

2

3

4

5

6

7

8

9

10

 

Pre-treatment ABR, events/yeara

5.33

4.0

1.33

0

2.0

7.33

3.0

2.67

3.0

0.67

 

ABR After gene therapy, events/yearb

0.59

0

0

1.61

0.80

0.51

0

1.70

0.61

1.29

 

                aAnnualized data are based on the retrospective collection, three years prior to treatment
                bAnnualized data are from ≥15 days post-infusion to the last follow up available as of the data cut, no distinction is made between treated and untreated bleeds

Follow-up data on annualized FIX consumption per patient have been published here2 and are summarized as follows:

Effect of Gene Therapy on Annualized FIX Consumption Rate as shown in Table S12

Vector dose (vg/kg)

3.84e11 vg/kg

1.28e12 vg/kg

6.40e11 vg/kg

1.28e12 vg/kg

8.32e11 vg/kg

Patient Nr.

1

2

3

4

5

6

7

8

9

10

Pre-treatment, total IU/yeara

238,000

96,333

389,333

326,000

319,333

423,333

83,263

164.667

91,000

129,000

After gene therapy, total IU /yearb

0

0

0

95,532c

0

0

0

1,698

0

0

                aAnnualized data are based on the retrospective collection, three years prior to treatment
                bAnnualized data are from ≥15 days post-infusion to the last follow up available as of the data cut, no distinction is made between treated and untreated bleeds
                cPatient 4 resumed FIX prophylaxis in Month 13

Safety Details

No evidence of infusion-related reactions5

  • Observed FIX activities levels above 150% were individually assessed for risk of thrombosis, and one patient is being treated with DOACs5
  • The most common drug related SAE was transient transaminitis (in 4 pts.) requiring supplemental immunosuppression6

AEs Related to FLT180a that have been reported during the 26-week B-AMAZE trial and the follow-up long-term study have been published here2 and are summarized as follows:

Adverse Events Related to FLT180a as shown in Table 22

 

3.84e11 vg/kg (N=2)

1.28e12 vg/kg (N=2)

6.40e11 vg/kg (N=2)

8.32e11 vg/kg (N=4)


Event

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Any AE

0

0

2(100)

14

2(100)

4

4 (100)

11

Increased aminotransferasea

0

0

2(100)

5

2(100)

3

4 (100)

5

Fatigue or malaise

0

0

1(50)

2

0

0

1(25)

2

Increased coagulation FIX

0

0

2(100)

2

0

0

0

0

Muscle spasm, musculoskeletal pain, or myalgia

0

0

0

0

0

0

1(25)

3

Dyspepsia or eructation

0

0

1(50)

2

0

0

0

0

Arteriovenous fistula thrombosis

0

0

1(50)

1

0

0

0

0

Decreased coagulation FIX

0

0

0

0

1(50)

1

0

0

Headache

0

0

0

0

0

0

1(25)

1

Pulmonary sepsis

0

0

1(50)

1

0

0

0

0

Somnolence

0

0

1(50)

1

0

0

0

0

               aIncluded in this category are increased levels of either alanine aminotransferase or aspartate aminotransferase


AEs Related to Glucocorticoids that have been reported during the 26-week B-AMAZE trial and the follow-up long-term study have been published here2 and are summarized as follows:

Adverse Events Related to Glucocorticoids as shown in Table S22

 

3.84e11 vg/kg (N=2)

1.28e12 vg/kg (N=2)

6.40e11 vg/kg (N=2)

8.32e11 vg/kg (N=4)

Event

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Incidence

no. (%)

No. of

Events

Any AE

2 (100%)

2

2 (100%)

5

2 (100%)

11

3 (75%)

17

Folliculitis / Rash maculo-papular / dermatitis acneiform

1 (50%)

1

1 (50%)

1

2 (100%)

3

1 (25%)

1

Insomnia / Sleep disorder

 

 

 

 

2 (100%)

3

2 (50%)

4

Fatigue / Malaise

 

 

 

 

1 (50%)

1

1 (25%)

2

Cushingoid

 

 

 

 

2 (100%)

2

 

 

Muscle spasms / Musculoskeletal pain / Myalgia

 

 

 

 

 

 

1 (25%)

3

Blood glucose increased

 

 

 

 

 

 

1 (25%)

2

Abdominal pain upper

 

 

1 (50%)

1

 

 

 

 

Amylase increased

 

 

1 (50%)

1

 

 

 

 

Arthralgia

 

 

 

 

1 (50%)

1

 

 

Blood bilirubin increased

1 (50%)

1

 

 

 

 

 

 

Coagulation factor IX level increased

 

 

1 (50%)

1

 

 

 

 

Depression

 

 

 

 

 

 

1 (25%)

1

Dyspepsia / Eructation

 

 

 

 

1 (50%)

1

 

 

Increased appetite

 

 

 

 

 

 

1 (25%)

1

Lower respiratory tract infection

 

 

 

 

 

 

1 (25%)

1

Nasopharyngitis

 

 

 

 

 

 

1 (25%)

1

Tremor

 

 

 

 

 

 

1 (25%)

1

Troponin increased

 

 

 

 

 

 

1 (25%)

1

 

  • Co. 1 (3.84e11 vg/kg): No patient had increases in liver aminotransferase levels 2-3

The detailed course of liver aminotransferase levels, specifically considering all participants in Co. 2Co. 4, was described here2 as and is summarized follows:

  • Co. 2 (6.4e11 vg/kg):
    • In P4, the ALT level increased from approx. 10 U per liter in weeks 1 to 4 to 57 U per liter in week 5.
    • A second increase in the ALT level in P4 occurred approx. 22 weeks after gene therapy
    • At week 4, P5 had a mild increase in the ALT level (39 U per liter)
  • Co. 3 (8.32e11 vg/kg):
    • P7 had two episodes of increases in liver aminotransferase levels:
      • an initial breakthrough at week 5 and another
      • at week 16 after tapering of glucocorticoids
    • After the completion of tacrolimus, P8, P9 and P10 had increases in aminotransferase levels at or near month 6
  • Co. 4 (1.28e12 vg/kg):
    • P3 was treated with intravenous methylprednisolone and tacrolimus for vector-related increases in ALT levels at week 7
    • In P6, at week 4, the ALT level had increased to a peak of 69 U/L

AST elevations were not reported explicitly

Not reported3

The detailed course of steroid treatment for all participants was described here2 and is summarized as follows:

  • Co. 1 (3.84e11 vg/kg): Prophylactic immunosuppression consisted of tapering courses of prednisolone starting at 60 mg daily from week 6 to week 122
  • Co. 2 (6.4e11 vg/kg) and Co. 4 (1.28e12 vg/kg):  
    • Prophylactic immunosuppression initiated with 60 - 90 mg of prednisolone daily between week 3 and week 4 didn’t prevent increases in ALT levels
    • Vector-related increases in ALT levels were responsive to intravenous methylprednisolone and tacrolimus
  • Co. 3 (8.32e11 vg/kg): The immunosuppression regimen for P7 through P10 was amended to include prophylactic tacrolimus beginning alongside with glucocorticoids starting at week 3
    • Tacrolimus troughs in P7 were difficult to get into the desired range (10 to 15 ng/ml), possibly caused by a drug interaction with carbamazepine
    • P8, P9, and P10 all had FIX levels of more than 150% by week 4 or 5.
    • Prophylactic immunosuppression in P8, P9, and P10 with glucocorticoids and tacrolimus suppressed vector-related increases in liver aminotransferase levels,
      and high FIX levels were sustained throughout the 26-week trial period
    • P8, P9, and P10 received tacrolimus for 17 or 18 weeks with tacrolimus continued 6 to 8 weeks after cessation of glucocorticoids
    • After the completion of tacrolimus, all three pts. had increases in aminotransferase levels at or near month 6

According to Figure 22 and the corresponding results stated in that publication, certain ALT increases might be associated with a reduction in FIX transgene expression in the following participants:

  • Co. 1: Not applicable as no participant had increases in liver aminotransferase levels2-3
  • Co. 2 (6.4e11 vg/kg), prophylactic immunosuppression with prednisolone:
    • In P4, whose FIX levels decreased to less than 2% by month 11, the first ALT peak level (57 U/L) at week 4 corresponded with a temporary reduction in its FIX levels from 47% to around 25%
  • Co. 3 (8.32e11 vg/kg), prophylactic immunosuppression with glucocorticoids and tacrolimus:
    • The FIX levels in P7 decreased after the second episode of ALT elevation at week 16, dropped from about 220% to around 50%, which corresponded to a steady state from month 12 through month 22
  • Co. 4 (1.28e12 vg/kg), prophylactic immunosuppression with prednisolone:
    • In P3, vector-related increases in ALT levels at week 7 were consistent with a decrease in FIX levels from 167% at week 5 to around 90% at week 9, as depicted in Figure 2

Not reported

References:
  1. A Factor IX Gene Therapy Study (FIX-GT) (FIX-GT).  Available at: Study Details | A Factor IX Gene Therapy Study (FIX-GT) | ClinicalTrials.gov
  2. Chowdary P, Shapiro S, Makris M, Evans G, Boyce S, Talks K, Dolan G, Reiss U, Phillips M, Riddell A, Peralta MR, Quaye M, Patch DW, Tuddenham E, Dane A, Watissée M, Long A, Nathwani A. Phase 1-2 Trial of AAVS3 Gene Therapy in Patients with Hemophilia B. N Engl J Med. 2022 Jul 21;387(3):237-247. doi: 10.1056/NEJMoa2119913. PMID: 35857660. Phase 1–2 Trial of AAVS3 Gene Therapy in Patients with Hemophilia B | NEJM
  3. 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
  4. 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)
  5. 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
  6. 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

AAV, Adeno-associated virus; 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

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