Comparative Effectiveness of Valoctocogene Roxaparvovec and Prophylactic Factor VIII Replacement in Severe Hemophilia A

INTRODUCTION

A prospective, non-interventional study (270-902) followed 294 adults with severe hemophilia A (SHA) receiving prophylactic factor VIII (FVIII). From these participants, 112 rolled over into a single-arm, multicenter, phase 3 trial (GENEr8-1; NCT03370913) that evaluated efficacy and safety of valoctocogene roxaparvovec, a gene therapy that provides endogenous FVIII in individuals with SHA. Participants from 270-902 who did not roll over provide an opportunity for a contemporaneous external control. Therefore, the comparative effectiveness of valoctocogene roxaparvovec vs FVIII prophylaxis was evaluated using propensity scoring (PS).

METHODS

This post hoc analysis compared 112 participants from GENEr8-1 (treated cohort) to 73 participants in 270-902 who did not enroll in GENEr8-1 (control cohort). The primary analysis used standardized mortality ratio weighting to re-weight baseline characteristics of the control cohort to better match the treated cohort. Mean annualized bleeding rates (ABR) for treated and all bleeds were compared between cohorts along with the proportion of participants with zero bleeds (treated and all bleeds). Sensitivity and scenario analyses were also conducted.

RESULTS

PS adjustments reduced differences in baseline characteristics between cohorts. Mean treated (4.40 vs 0.85; P < 0.001) and all (5.01 vs 1.54; P < 0.001) ABR were significantly lower, and the proportions of participants with zero treated bleeds (82.1% vs 32.9%; P < 0.001) and all bleeds (58.0% vs 28.5%; P < 0.001) were significantly higher in GENEr8-1.

CONCLUSIONS

PS-adjusted analyses were consistent with prior intra-individual comparisons. Compared with participants receiving prophylactic FVIII, the participants receiving valoctocogene roxaparvovec experienced lower ABR, and a higher proportion had zero bleeds.

TRAIL REGISTRATION

ClinicalTrials.gov identifier, NCT03370913.

Efanesoctocog Alfa Versus Emicizumab in Adolescent and Adult Patients With Haemophilia A Without Inhibitors

INTRODUCTION

The phase 3 XTEND-1 trial (NCT04161495) demonstrated that efanesoctocog alfa prophylaxis provided superior bleed protection compared with pre-trial factor VIII (FVIII) prophylaxis in patients with severe haemophilia A. The aim of this study was to indirectly compare the efficacy of efanesoctocog alfa with non-factor replacement therapy emicizumab in adolescent and adult patients with severe haemophilia A without inhibitors.

METHODS

A systematic literature review was conducted to identify phase 3 trials of emicizumab. Matching-adjusted indirect comparisons were used to compare annualised bleeding rates (ABRs) for any, treated, joint, and spontaneous bleeds, and joint health (measured using Hemophilia Joint Health Score [HJHS]), between efanesoctocog alfa and emicizumab. Estimated effects for different emicizumab regimens were pooled using random-effect meta-analysis to evaluate the overall difference in bleed outcomes between efanesoctocog alfa and emicizumab.

RESULTS

One emicizumab trial was included (HAVEN 3), which investigated three dosing regimens. In meta-analyses, efanesoctocog alfa once-weekly (Q1W) was associated with significantly lower ABRs for any (incidence rate ratio [95% CI] 0.33 [0.20; 0.53]), any treated (0.49 [0.30; 0.80]) and treated joint (0.51 [0.28; 0.91]) bleeds compared with emicizumab Q1W in non-inhibitor patients with prior prophylaxis or on-demand treatment. Efanesoctocog alfa Q1W was also associated with a significantly better improvement from baseline in HJHS Joint Score (mean difference [95% CI] -2.06 [-3.97; -0.14]) and Total Score (-2.37 [-4.36; -0.39]) versus emicizumab Q1W or every 2 weeks.

CONCLUSION

Efanesoctocog alfa prophylaxis was associated with significantly lower rates of any, treated, and joint bleeds and improved joint health compared with emicizumab in patients with severe haemophilia A.