Patient Experience With Efanesoctocog Alfa for Severe Hemophilia A: Results From the XTEND-1 Phase 3 Clinical Study Exit Interviews.

Purpose: Hemophilia A is a rare bleeding disorder that leads to recurrent hemarthrosis, which can ultimately result in reduced mobility and poor quality of life. Qualitative exit interviews provide insights into patient perspectives and support the interpretation of quantitative trial data, such as patient-reported outcome measures. In the Phase 3 XTEND-1 study (NCT04161495) of efanesoctocog alfa in participants with severe hemophilia A, exit interviews were conducted to understand pre- and post-study experiences with pain and physical functioning and to evaluate participants' treatment experiences.

Methods: In XTEND-1, participants (≥12 years old) received once-weekly efanesoctocog alfa prophylaxis 50 IU/kg for 52 weeks (Arm A) or on-demand efanesoctocog alfa 50 IU/kg for 26 weeks followed by 26 weeks once-weekly prophylaxis (50 IU/kg; Arm B). Optional qualitative exit interviews were conducted using a semi-structured guide in a subset of participants following study completion. Interviews included open-ended questions about participants' pre- and post-study experiences with hemophilia A and targeted questions relating to improvements in patient-reported outcomes assessed during XTEND-1, including the Haemophilia Quality of Life Questionnaire for Adults Physical Health subscale (Haem-A-QoL PH). Content validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity 3a measure was also assessed, particularly the worst pain item.

Findings: Exit interviews were conducted with 29 of 159 patients enrolled in XTEND-1 (mean [range] age 40 [16-73] years). Of 17 participants enrolled in Arm A, 13 (76.5%) reported a "wearing off" feeling with pre-study treatment, including more aches/pain, breakthrough bleeds, and limited physical activities. Joint pain was the most reported pre-study symptom (96.6%; n = 28/29), followed by a reduced ability to move without pain (89.7%, n = 26/29). Improvements following efanesoctocog alfa prophylaxis in ≥1 Haem-A-QoL PH domain were reported by 89.7% (n = 26/29) of participants, with improvements in joint pain, the ability to move without pain, and painful swellings reported by at least 21 (84%) participants. Participants reported that the PROMIS Pain Intensity 3a items were relevant, clear, and easy to answer. Most participants (96.6%) were "quite satisfied" or "very satisfied" with efanesoctocog alfa prophylaxis. All participants preferred efanesoctocog alfa over pre-study treatment.

Implications: The exit interviews demonstrated that once-weekly efanesoctocog alfa prophylaxis resulted in patient-relevant and meaningful improvements in pain and physical functioning, consistent with the quantitative findings from XTEND-1. These results support the validity of the Haem-A-QoL PH and PROMIS Pain Intensity 3a assessed during XTEND-1, demonstrating the potential for change with efficacious treatment.

Trial registry: ClinicalTrials.gov TRIAL REGISTRATION NUMBER: NCT04161495 REGISTRY URL: https://clinicaltrials.gov/study/NCT04161495.