Giroctocogene fitelparvovec gene therapy for severe hemophilia A: 104-week analysis of the phase 1/2 Alta study

ABSTRACT

Patients with hemophilia A require exogenous factor VIII (FVIII) or nonfactor hemostatic agents to prevent spontaneous bleeding events. Adeno-associated virus (AAV) vector-based gene therapy is under clinical investigation to enable endogenous FVIII production. Giroctocogene fitelparvovec is a recombinant AAV serotype 6 vector containing the coding sequence for the B-domain-deleted human F8 gene. In the ongoing phase 1/2, dose-ranging Alta study, 4 sequential cohorts of male participants with severe hemophilia A received a single IV dose of giroctocogene fitelparvovec. The primary end points are safety and changes in circulating FVIII activity. Interim results up to 214 weeks after treatment for all participants are presented. Eleven participants were dosed. Increases in alanine and aspartate aminotransferases were the most common treatment-related adverse events (AEs), which resolved with corticosteroid administration. Two treatment-related serious AEs (hypotension and pyrexia) were reported in 1 participant within 6 hours of infusion and resolved within 24 hours after infusion. At the highest dose level (3 × 1013 vg/kg; n = 5), the mean circulating FVIII activity level at week 52 was 42.6% (range, 7.8%-122.3%), and at week 104 it was 25.4% (range, 0.9%-71.6%) based on a chromogenic assay. No liver masses, thrombotic events, or confirmed inhibitors were detected in any participant. These interim 104-week data suggest that giroctocogene fitelparvovec is generally well tolerated with appropriate clinical management and has the potential to provide clinically meaningful FVIII activity levels, as indicated by the low rate of bleeding events in the highest dose cohort. This trial was registered at www.clinicaltrials.gov as #NCT03061201.

Treatment Burden of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Randomized Study

Context

Somatrogon is a long-acting recombinant human growth hormone treatment developed as a once-weekly treatment for pediatric patients with growth hormone deficiency (GHD).

Objective

Evaluate patient and caregiver perceptions of the treatment burden associated with the once-weekly somatrogon injection regimen vs a once-daily Somatropin injection regimen.

Methods

Pediatric patients (≥3 to <18 years) with GHD receiving once-daily somatropin at enrollment were randomized 1:1 to Sequence 1 (12 weeks of once-daily Somatropin, then 12 weeks of once-weekly somatrogon) or Sequence 2 (12 weeks of once-weekly somatrogon, then 12 weeks of once-daily Somatropin). Treatment burden was assessed using validated questionnaires completed by patients and caregivers. The primary endpoint was the difference in mean overall life interference (LI) total scores after each 12-week treatment period (somatrogon vs Somatropin), as assessed by questionnaires.

Results

Of 87 patients randomized to Sequence 1 (n = 43) or 2 (n = 44), 85 completed the study. Once-weekly somatrogon had a significantly lower treatment burden than once-daily Somatropin, based on mean overall LI total scores after somatrogon (8.63) vs Somatropin (24.13) treatment (mean difference –15.49; 2-sided 95% CI –19.71, –11.27; P < .0001). Once-weekly somatrogon was associated with greater convenience, higher satisfaction with treatment experience, and less LI. The incidence of treatment-emergent adverse events (TEAEs) for Somatropin and somatrogon was 44.2% and 54.0%, respectively. No severe or serious AEs were reported.

Conclusion

In pediatric patients with GHD, once-weekly somatrogon had a lower treatment burden and was associated with a more favorable treatment experience than once-daily Somatropin.

Perception of Treatment Burden With Once Weekly Somatrogon vs Once Daily Genotropin in Pediatric Patients With Growth Hormone Deficiency (GHD): Results From a Randomized Phase 3 Study

Background: Somatrogon is a long-acting recombinant human growth hormone (rhGH) comprised of the amino acid sequence of hGH and 3 copies of the carboxy-terminal peptide from human chorionic gonadotropin. Somatrogon is being developed as a once weekly subcutaneous (SC) injectable treatment for pediatric patients (pts) with GHD.

Aims: To evaluate patient and caregiver perceptions of the treatment burden associated with a once weekly somatrogon SC injection schedule compared with a once daily Genotropin SC injection schedule.

Methods: In this phase 3 (NCT03831880), open-label, crossover study, pediatric pts (3 to &lt;18 years) with GHD on at least 3 months stable rhGH therapy were randomized 1:1 to receive treatment according to 1 of 2 sequences: Sequence #1, 12 weeks of Genotropin once daily followed by 12 weeks of somatrogon once weekly; Sequence #2, 12 weeks of somatrogon once weekly followed by 12 weeks of Genotropin once daily. The primary objective of the study was to evaluate treatment burden assessed as the difference between mean overall Life Interference (LI) total scores after each 12-week treatment period of weekly somatrogon and daily Genotropin. Secondary objectives further assessed treatment experience of pts and caregivers after each treatment period and their comparison of both treatments at the end of the study. A recently developed, validated dyad questionnaire (Turner-Bowker DM et al, 2020) was administered as an electronic Patient Reported Outcome to collect all assessments.

Results: Eighty-seven pts were randomized to Sequence #1 (n=43) or Sequence #2 (n=44) with 85 pts completing the study. Somatrogon administered as a once weekly injection had a lower (statistically significant) treatment burden than Genotropin administered as a once daily injection, based on the mean overall LI total scores after somatrogon (8.63) vs Genotropin (24.13) treatment (mean difference: -15.49; two-sided 95% CI: [-19.71, -11.27]; P &lt;0.0001). Compared with once daily Genotropin, once weekly somatrogon was associated with greater convenience, higher satisfaction with treatment experience, and less life interference for the caregiver. A higher proportion of pts preferred once weekly somatrogon and demonstrated a greater intent to comply with treatment. The proportion of pts who experienced at least one treatment-emergent adverse event (TEAE) with Genotropin and somatrogon treatment were 44.2% and 54.0%, respectively. Injection site pain was the most common TEAE during the Genotropin (12.8%) and somatrogon (14.9%) treatment periods and was rated as mild in most cases. No severe or serious adverse events were reported.

Conclusions: In pediatric pts with GHD, compared with Genotropin administered once daily, somatrogon administered once weekly has a lower treatment burden as shown by less life interference, and is associated with a more favorable treatment experience.