California-based Sangamo Therapeutics, alongside its partner Pfizer, has announced interim results from Phase I/II Alta study evaluating an investigational SB-525 gene therapy for severe haemophilia A.

In the eight patients dosed the therapy was generally well-tolerated and demonstrated a dose-dependent increase in Factor VIII levels across four different dose cohorts.

As a result, the Safety Monitoring Committee has recommended a cohort expansion.

SB-525 comprises a recombinant adeno-associated virus serotype 6 vector (AAV6) encoding the complementary deoxyribonucleic acid for B domain deleted human FVIII.

Sangamo chief medical officer Edward Conner said: “The interim data from the first eight patients with haemophilia A treated with SB-525 gene therapy in the Alta study are encouraging and demonstrate a dose-dependent relationship, evidence of sustained factor levels, and low variability, both within each patient and within each cohort.

“We need to continue observing how the data mature and how additional patients in the expansion cohort respond to SB-525. We look forward to working with Pfizer to potentially advance SB-525 into a registrational study.”

Pfizer rare disease research unity senior vice-president and chief scientific officer Seng Cheng said: “We are encouraged by the early clinical data suggesting tolerability of the recombinant AAV6 vector and potential for normalization of Factor VIII levels.

“We look forward to the opportunity to expanding the cohort administered a 3e13 vg/kg dose and subsequent planning for the pivotal study.

“As the development and commercial partner for SB-525, we are encouraged by the possibility that SB-525 may one day transform the treatment landscape for patients with haemophilia A.”

Sangamo also announced promising early from the first patient dosed in a Phase I/II study of ST-400 gene therapy for patients with beta thalassemia, which it is developing with Sanofi. The patient has the most severe form of transfusion-dependent beta thalassemia (ß°/ß°).

University of Minnesota’s Division of Paediatric Blood and Marrow Transplantation associate professor Angela Smith said: “”While these data are very early and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusion, they are promising.

“These initial results are especially encouraging given the p