Investigational gene therapy shows promise in hemophilia A

SAN DIEGO – Investigational SPK-8011 gene transfer results in safe, durable, dose-dependent Factor VIII (FVIII) expression in patients with severe or moderately severe hemophilia A, according to preliminary findings from an ongoing phase 1/2 study.

An overall reduction of 97% was seen in both the annualized bleeding rate (ABR) and annualized infusion rate (AIR) in the first 12 patients treated with SPK-8011, which is a Spark Therapeutics product that consists of a bioengineered AAV capsid expressing B domain-deleted FVIII under the control of a liver-specific promoter, principal investigator Lindsey A. George, MD, reported at the annual meeting of the American Society of Hematology.

Study subjects were men aged 18-52 years, including 11 with severe disease and 1 with moderately severe disease, who received a single infusion of either 5E11 vg/kg (2 patients), 1E12 vg/kg (3 patients), or 2E12 vg/kg (7 patients).

“All vector doses led to expression of FVIII levels adequate to prevent bleeding and allow cessation of prophylaxis,” said Dr. George, associate professor of pediatrics at the Perelman School of Medicine, University of Pennsylvania, Philadelphia, and an attending physician in the division of hematology at Children’s Hospital of Philadelphia.

In the two men in the 5E11 dose cohort, mean FVIII levels beginning 12 weeks after infusion were 13%, and neither experienced bleeding events, had elevated transaminase levels, or required steroids, she said, noting that FVIII expression remained stable for at least 66 weeks (and up to 78 weeks in one patient).

The three men in the 1E12 dose cohort had mean FVIII levels of 15% beginning at 12 weeks post infusion, and the levels were stable for at least 46 weeks.

The first patient was infused with a single dose of factor concentrate for a spontaneous joint bleed at day 159, and the second patient received multiple infusions for a traumatic bleed beginning at day 195. Both received a successful course of tapering steroids, at 12 and 7 weeks after infusion, respectively, for declining FVIII levels, Dr. George said.

The third subject had no bleeding and did not receive factor infusions or steroids, she added.

In the highest dose cohort (2E12), five of seven subjects had FVIII levels between 16% and 49%.

Steroids were required and given between 6 and 11 weeks after infusion in five of the seven patients in that cohort for either declining FVIII levels, a rise in alanine aminotransferase (ALT) above baseline, or elevated IFN-g ELISPOTs to AAV capsid. The steroids normalized ALT levels and extinguished the ELISPOT signal in all cases.

In two patients, FVIII levels showed limited stabilization, and fell to less than 6%. This was most likely due to the immune response, Dr. George explained, noting that in one of the two patients no bleeds were reported through 12 weeks of follow-up, while the other experienced four bleeds through 37 weeks of observation.

SPK-8011 was well tolerated in this study, which had cumulative follow-up of 506 weeks at the time of Dr. George’s presentation. No inhibitor formation was noted in the safety analysis and the only serious adverse event – the immune response to AAV capsid – has resolved, she said.

Data from the lowest dose cohort (5E11) are consistent with published natural history data indicating FVIII:C 12% is adequate to prevent spontaneous bleeding events, she said. However, she noted that the loss of some FVIII expression in two patients in the 2E12 dose cohort (which eventually stabilized on steroids), and the fact that five of seven subjects in this cohort required steroids, suggests a possible role for prophylactic steroid administration in patients treated with SPK-8011.

“Gene transfer for hemophilia A offers the potential for a one-time disease-altering treatment that eliminates bleed risk and could free patients from the burden of lifelong chronic therapy,” Dr. George said.

A phase 3 run-in study is planned, she added.

Spark Therapeutics sponsored the study. Dr. George reported equity ownership related to the University of Pennsylvania and consultancy for Pfizer.

[email protected]

SOURCE: High K et al., ASH 2018, Abstract 487.

SAN DIEGO – Investigational SPK-8011 gene transfer results in safe, durable, dose-dependent Factor VIII (FVIII) expression in patients with severe or moderately severe hemophilia A, according to preliminary findings from an ongoing phase 1/2 study.

An overall reduction of 97% was seen in both the annualized bleeding rate (ABR) and annualized infusion rate (AIR) in the first 12 patients treated with SPK-8011, which is a Spark Therapeutics product that consists of a bioengineered AAV capsid expressing B domain-deleted FVIII under the control of a liver-specific promoter, principal investigator Lindsey A. George, MD, reported at the annual meeting of the American Society of Hematology.

Study subjects were men aged 18-52 years, including 11 with severe disease and 1 with moderately severe disease, who received a single infusion of either 5E11 vg/kg (2 patients), 1E12 vg/kg (3 patients), or 2E12 vg/kg (7 patients).

“All vector doses led to expression of FVIII levels adequate to prevent bleeding and allow cessation of prophylaxis,” said Dr. George, associate professor of pediatrics at the Perelman School of Medicine, University of Pennsylvania, Philadelphia, and an attending physician in the division of hematology at Children’s Hospital of Philadelphia.

In the two men in the 5E11 dose cohort, mean FVIII levels beginning 12 weeks after infusion were 13%, and neither experienced bleeding events, had elevated transaminase levels, or required steroids, she said, noting that FVIII expression remained stable for at least 66 weeks (and up to 78 weeks in one patient).

The three men in the 1E12 dose cohort had mean FVIII levels of 15% beginning at 12 weeks post infusion, and the levels were stable for at least 46 weeks.

The first patient was infused with a single dose of factor concentrate for a spontaneous joint bleed at day 159, and the second patient received multiple infusions for a traumatic bleed beginning at day 195. Both received a successful course of tapering steroids, at 12 and 7 weeks after infusion, respectively, for declining FVIII levels, Dr. George said.

The third subject had no bleeding and did not receive factor infusions or steroids, she added.

In the highest dose cohort (2E12), five of seven subjects had FVIII levels between 16% and 49%.

Steroids were required and given between 6 and 11 weeks after infusion in five of the seven patients in that cohort for either declining FVIII levels, a rise in alanine aminotransferase (ALT) above baseline, or elevated IFN-g ELISPOTs to AAV capsid. The steroids normalized ALT levels and extinguished the ELISPOT signal in all cases.

In two patients, FVIII levels showed limited stabilization, and fell to less than 6%. This was most likely due to the immune response, Dr. George explained, noting that in one of the two patients no bleeds were reported through 12 weeks of follow-up, while the other experienced four bleeds through 37 weeks of observation.

SPK-8011 was well tolerated in this study, which had cumulative follow-up of 506 weeks at the time of Dr. George’s presentation. No inhibitor formation was noted in the safety analysis and the only serious adverse event – the immune response to AAV capsid – has resolved, she said.

Data from the lowest dose cohort (5E11) are consistent with published natural history data indicating FVIII:C 12% is adequate to prevent spontaneous bleeding events, she said. However, she noted that the loss of some FVIII expression in two patients in the 2E12 dose cohort (which eventually stabilized on steroids), and the fact that five of seven subjects in this cohort required steroids, suggests a possible role for prophylactic steroid administration in patients treated with SPK-8011.

“Gene transfer for hemophilia A offers the potential for a one-time disease-altering treatment that eliminates bleed risk and could free patients from the burden of lifelong chronic therapy,” Dr. George said.

A phase 3 run-in study is planned, she added.

Spark Therapeutics sponsored the study. Dr. George reported equity ownership related to the University of Pennsylvania and consultancy for Pfizer.

[email protected]

SOURCE: High K et al., ASH 2018, Abstract 487.

SAN DIEGO – Investigational SPK-8011 gene transfer results in safe, durable, dose-dependent Factor VIII (FVIII) expression in patients with severe or moderately severe hemophilia A, according to preliminary findings from an ongoing phase 1/2 study.

An overall reduction of 97% was seen in both the annualized bleeding rate (ABR) and annualized infusion rate (AIR) in the first 12 patients treated with SPK-8011, which is a Spark Therapeutics product that consists of a bioengineered AAV capsid expressing B domain-deleted FVIII under the control of a liver-specific promoter, principal investigator Lindsey A. George, MD, reported at the annual meeting of the American Society of Hematology.

Study subjects were men aged 18-52 years, including 11 with severe disease and 1 with moderately severe disease, who received a single infusion of either 5E11 vg/kg (2 patients), 1E12 vg/kg (3 patients), or 2E12 vg/kg (7 patients).

“All vector doses led to expression of FVIII levels adequate to prevent bleeding and allow cessation of prophylaxis,” said Dr. George, associate professor of pediatrics at the Perelman School of Medicine, University of Pennsylvania, Philadelphia, and an attending physician in the division of hematology at Children’s Hospital of Philadelphia.

In the two men in the 5E11 dose cohort, mean FVIII levels beginning 12 weeks after infusion were 13%, and neither experienced bleeding events, had elevated transaminase levels, or required steroids, she said, noting that FVIII expression remained stable for at least 66 weeks (and up to 78 weeks in one patient).

The three men in the 1E12 dose cohort had mean FVIII levels of 15% beginning at 12 weeks post infusion, and the levels were stable for at least 46 weeks.

The first patient was infused with a single dose of factor concentrate for a spontaneous joint bleed at day 159, and the second patient received multiple infusions for a traumatic bleed beginning at day 195. Both received a successful course of tapering steroids, at 12 and 7 weeks after infusion, respectively, for declining FVIII levels, Dr. George said.

The third subject had no bleeding and did not receive factor infusions or steroids, she added.

In the highest dose cohort (2E12), five of seven subjects had FVIII levels between 16% and 49%.

Steroids were required and given between 6 and 11 weeks after infusion in five of the seven patients in that cohort for either declining FVIII levels, a rise in alanine aminotransferase (ALT) above baseline, or elevated IFN-g ELISPOTs to AAV capsid. The steroids normalized ALT levels and extinguished the ELISPOT signal in all cases.

In two patients, FVIII levels showed limited stabilization, and fell to less than 6%. This was most likely due to the immune response, Dr. George explained, noting that in one of the two patients no bleeds were reported through 12 weeks of follow-up, while the other experienced four bleeds through 37 weeks of observation.

SPK-8011 was well tolerated in this study, which had cumulative follow-up of 506 weeks at the time of Dr. George’s presentation. No inhibitor formation was noted in the safety analysis and the only serious adverse event – the immune response to AAV capsid – has resolved, she said.

Data from the lowest dose cohort (5E11) are consistent with published natural history data indicating FVIII:C 12% is adequate to prevent spontaneous bleeding events, she said. However, she noted that the loss of some FVIII expression in two patients in the 2E12 dose cohort (which eventually stabilized on steroids), and the fact that five of seven subjects in this cohort required steroids, suggests a possible role for prophylactic steroid administration in patients treated with SPK-8011.

“Gene transfer for hemophilia A offers the potential for a one-time disease-altering treatment that eliminates bleed risk and could free patients from the burden of lifelong chronic therapy,” Dr. George said.

A phase 3 run-in study is planned, she added.

Spark Therapeutics sponsored the study. Dr. George reported equity ownership related to the University of Pennsylvania and consultancy for Pfizer.

[email protected]

SOURCE: High K et al., ASH 2018, Abstract 487.