• ClinicalTrials.gov Identifier: NCT03003533¹ (A Gene Transfer Study for Hemophilia A) and
  NCT03432520² (Long-Term Safety and Efficacy of Spark-Sponsored Gene Therapies in Males With Hemophilia A)
• A phase 1/2 study³

The status of the trial was reported on ClinicalTrials.gov¹ as follows:

• Active, not recruiting
• Last Update Posted: July 10, 2023

The key inclusion criteria were reported here^3, 4, 5 as follows:

• Male ≥18 years of age
• Plasma FVIII activity levels ≤ 2% of normal
• Have received >150 EDs to FVIII concentrates or cryoprecipitate
• <1:1 neutralizing antibodies titers to SPK200 capsid
• Experienced >10 bleeding events over the previous 12 months prior to screening
• No measurable inhibitors or history of clinically significant inhibitors

The key exclusion criteria were reported here^4, 5 as follows:

• Participated in a gene transfer trial within the last 52 weeks or in a clinical trial with an investigational product within the last 12 weeks
• Active hepatitis B or C
• Significant underlying liver disease
• Serological evidence of human immunodeficiency virus (HIV) with CD4 counts ≤200/mm3

Data regarding the utilized AAV serotype and the vector manufacturing platform were collected from here^3, 5  and summarized as follows:

• Bioengineered AAV, LK03/Spark200
• Plasmid/HEK293 cells

B domain–deleted FVIII (FVIII-SQ) with no CpG motifs in the open reading frame under the control of a liver-specific promoter^3, 5 

Data regarding the utilized expression cassette components were collected from here^3, 5 and summarized as follows:

• Liver-specific promoter consisting of a truncated transthyretin enhancer and a truncated transthyretin promoter
• The FVIII expression cassette also includes a synthetic intron sequence and a rabbit beta-globin polyA signal

Systemic – intravenous infusion³

Follow-up times were reported here^{1, 2, 3} as follows:

• Phase 1/2 study - 52 weeks follow-up¹
• Long-term study has a follow-up period of 9 years, ensuring 10 years of follow-up post-infusion²

One-stage FVIII assay (OS)³

Data on FVIII activity levels from week 52 to beyond week 208, as reported in reference #4, are summarized as follows: 

* Participant terminated study participation due to site closure;

† Sample >208 weeks unable to be processed. Analysis includes participants with >52 weeks of follow up (n=16);
   data for two participants (#5 & #12), who lost compete transgene FVIII expression following presumed capsid immune response, are censored.

The subsequent information was extracted from here^3,* and summarized as follows:

• The initial peak FVIII expression occurred 6 - 12 weeks after vector administration across all the dose cohorts
• Pts. in the “low dose cohorts” (5e11 - 1e12 vg/kg) reached plateau FVIII activity by 12 weeks 
• Pts. in the “high dose cohorts” (1.5-2e12 vg/kg) except P6 reached plateau expression by 26 to 52 weeks

^* Data cut-off May 3, 2021; 18 participants; median efficacy follow-up 33.4 months (range 3.7 to 47.6)

Information related to ABR data was collected from here^3-4 and is summarized as follows:

     ^*Data cut-off May 3, 2021; 18 participants; median efficacy follow-up 33.4 months (range 3.7 to 47.6)
 

• 76% of participants had an ABR of <1 for treated bleeds and 90% of participants had an ABR of <1 for spontaneous bleeds

     ^† Data cut-off Oct 4, 2022; 23 participants; median efficacy follow-up: 172.1 (2-285) weeks
 

Median annualized numbers of FVIII infusions per year before and per year after vector administration were reported here^3, 4 as follows: 

    ^* Data cut-off May 3, 2021; 18 participants; median efficacy follow-up 33.4 months (range 3.7 to 47.6)
    ^† For Participants 5 & 12, the reported efficacy data were based on observations before loss of FVIII expression
 

    ^†† Data cut-off Oct 4, 2022; 23 participants; median efficacy follow-up: 172.1 (2-285) weeks
 

Information related to IRR data was collected from here^3, 4 and is summarized as follows:

• 1/24 participants (P5; 2e12 vg/kg cohort) had an infusion reaction consisting of vomiting, myalgia, back pain and pyrexia
• This IRR resolved within 72 hours outpatient antipyretic therapy

* Data cutoff Oct 4. 2022; Median range follow-up (n=24); 191 (2-285 weeks)

AEs related to SPK-8011, as reported in reference #3, are summarized as follows: 

* There were no drug-related adverse events or serious adverse events in 5×1011 and 1×1012 vg/kg cohorts.
Data cut-off May 3, 2021; 18 participants; median safety observation period 36.6 months (range 5.5 to 50.3)

AEs related to glucocorticoid use, as reported in reference #3, are summarized as follows: 

Additional Safety Information was reported in the ASH 2022 Croteau presentation^4,*  , as follows:

• No deaths, no FVIII inhibitor development, and no thrombotic events were reported in any of the 24 study participants.
• Eleven participants experienced elevated LFTs. All events were transient, asymptomatic, and resolved.
• AEs related to immunomodulatory agents were mild to moderate and reported in 8 participants
• These events included weight gain, insomnia, irritability, fatigue, hypertension, neutropenia, decreased appetite, stomach
  pain, nausea, headache, hyperactivity, hot flushes, generalized edema, acne, hypomagnesemia, and muscle cramping
• By the October 4, 2022 cutoff, all of these AEs resolved, except hypertension (n=1), headache (n=1) and nausea and stomach pain (n=1)

^* Data cutoff Oct 4. 2022; Median range follow-up (n=24); 191 (2-285 weeks)

11 participants reported ALT elevations⁴ as follows:

• Grade 1 (n=9)
• Grade 2 (n=1)^*
• Grade 3 (n=1)

^* The Grade 2 ALT elevation was deemed an SAE due to in elective hospitalization for IV steroid administration. Data cut-off Oct 4, 2022

Not reported ^3, 4

Not reported

Information regarding use and duration of steroid treatment was collected from here^3, 6 and is summarized as follows:

• In total, 17/23 Participants received corticosteroids*
• All corticosteroids were started within 12 weeks
  • Median (range) time to initiation of reactive corticosteroids (n=12) † was 9.3 (4.3- 12.1) weeks
  • Median (range) duration of treatment was 8.5 (2.0-18.0) weeks
• Corticosteroids were administered prophylactically in 5 participants 2-4 weeks following vector administration
  • The length of exposure in 4 participants was prolonged (31–49 weeks); attempted corticosteroid tapering resulted in changes associated with presumed capsid immune response in all 4 participants.
• All five participants who received prophylactic corticosteroids and four participants who received reactive corticosteroids experienced a recurrence of one or more laboratory trigger(s) potentially
  linked to a presumed capsid immune response during their corticosteroid taper

The subsequent data on corticosteroid treatment per participant and dose cohort were extracted from Figure 1 in reference #6 and are summarized as follows:

*Data cut-off June 30, 2022. A. Gray shaded rows indicate two participants (#5 & #12) who lost compete transgene FVIII expression and initiated emicizumab following presumed capsid immune response
† Dose of SPK-8011: 1 × 1012 vg/kg, n=2; 2 × 1012 vg/kg, n=5; 1.5 × 1012 vg/kg, n=5
 

2/24 participants (2e12 vg/kg cohort; Participants 5 & 12) lost expression after a presumed cellular immune response against SPK200^*, 3-4 
* Data cut-off Oct 4, 2022

None ^3-4

1. A Gene Transfer Study for Hemophilia A. ClinicalTrials.gov identifier: NCT03003533. Link
2. Long-Term Safety and Efficacy of Spark-Sponsored Gene Therapies in Males With Hemophilia A. ClinicalTrials.gov identifier: NCT03432520. Link
3. George LA, Monahan PE, Eyster ME, Sullivan SK, Ragni MV, Croteau SE, et al. Multiyear Factor VIII Expression after AAV Gene Transfer for Hemophilia A. N Engl J Med. 2021 Nov 18;385(21):1961-1973. doi: 10.1056/NEJMoa2104205. PMID: 34788507; PMCID: PMC8672712. Link
4. Croteau, S.E., et al., Long-Term Durable FVIII Expression with Improvements in Bleeding Rates Following AAV-Mediated FVIII Gene Transfer for Hemophilia A: Multiyear Follow-up on the Phase I/II Trial of SPK-8011 [oral presentation]. ASH Annual Meeting and Exposition, 2022. Blood. 2022;140(Suppl. 1):1899-1901. Link
5. George, L.A., et al., Multiyear Factor VIII Expression after AAV Gene Transfer for Hemophilia A: Supplementary Appendix. N Engl J Med. 2021;385(21):1961-1973. Link
6. Evans, M.S., et al., The Effects of Immunomodulation with Corticosteroids to Manage an AAV Capsid Immune Response in the Phase I/II Study of SPK-8011 [poster presentation]. ASH Annual Meeting and Exposition, 2022. Blood. 2022;140(Suppl. 1):10654-10655. Abstract 4779. Link

AAV, Adeno-associated virus; AEs, 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