SPK-8016 is in development for the treatment of patients with inhibitors to FVIII. This Phase 1/2, open-label, non-randomized, dose-finding study to evaluate the safety, efficacy, and tolerability of SPK-8016 in adult males with severe hemophilia A and no measurable inhibitor against FVIII.

Inclusion Criteria:

1. Be male and ≥18 years of age;

2. Have clinically severe hemophilia A, defined as:

   1. <1% (<1 IU/dL) endogenous FVIII activity levels as historically documented by a certified laboratory or screening data results; OR
   2. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and > 10 bleeding events per year (in the last 52 weeks prior to screening); OR
   3. 1-2% (1-2 IU/dL) endogenous FVIII activity levels and on prophylaxis;

3. Have had >150 exposure days (EDs) to any recombinant and/or plasma-derived FVIII concentrates or cryoprecipitates

4. Have no prior history of hypersensitivity or anaphylaxis associated with any FVIII or IV immunoglobulin administration

5. Have no measurable inhibitor against FVIII as assessed by central laboratory, have no confirmed history of clinically significant FVIII inhibitor, and no clinical signs or symptoms of decreased response to FVIII administration (Note: family history of inhibitors will not exclude study participation)

6. Agree to use reliable barrier contraception after the administration of SPK-8016 until notified by the Investigator.

Exclusion Criteria:

1. Have active hepatitis B or C
2. Have significant underlying liver disease.
3. Have serological evidence of HIV-1 or HIV-2 with CD4 counts ≤200/mm3. Participants who are HIV-positive and stable, with an adequate CD4 count (>200/mm3) and undetectable viral load, and are on an antiretroviral drug regimen are eligible to enroll
4. Have detectable antibodies reactive with AAV-Spark capsid
5. Have history of chronic infection or other chronic disease
6. Have been dosed in a previous gene therapy research trial within the last 52 weeks or with an investigational drug within the last 12 weeks
7. Any concurrent clinically significant major disease (such as liver abnormalities or type I diabetes) or other condition that, in the opinion of the Investigator and/or Sponsor, makes the subject unsuitable for participation in the study;
8. Unable or unwilling to comply with the schedule of visits and study assessments described in the clinical protocol.

Genetically male