Characteristics of participants
We conducted in-depth semi-structured interviews with 28 stakeholders between June 2019 and April 2021. The interviewees were eight medical oncologists, two specialized oncology nurse practitioners, three research nurses, one hematologist, one hospital pharmacist, three patients, two patient representatives, three scientists, and five policy-makers. They had an average age of 47 years (range: 30–73) and all but one policy-maker noted to be knowledgeable about HDCT.All healthcare providers were employed in the Netherlands by either a university hospital, a specialized oncology center, or a teaching hospital and had on average 10 years (range: 1–25) hands-on experience with the treatment.