INTRODUCTION
Intensive treatment including high-dose chemotherapy (HDC) with
autologous stem cell transplantation (SCT) is the standard care for
high-risk neuroblastoma.1 The importance of HDC is
well recognized, even after improvement of treatment outcomes by
anti-GD2 antibody immunotherapy, so re-evaluation of the efficacy and
safety of the HDC regimen is ongoing in several clinical
trials.2 Recently, the International Society of
Paediatric Oncology European Neuroblastoma (SIOPEN) conducted a
randomized trial and proved the superiority of busulfan and melphalan
over melphalan, etoposide, and carboplatin as a conditioning HDC
regimen.3
Thiotepa is an alkylating anticancer agent broadly used in the HDC
regimen at various dosages and schedules including both
single4 and tandem settings5–7. In
Japan, a unique HDC regimen called the double-conditioning regimen is
widely used in some major pediatric cancer centers, in which thiotepa
and melphalan are administered for 2 consecutive weeks. Hara et al.
(1998) reported the feasibility and efficacy of the double-conditioning
regimen for various solid tumors, including
neuroblastoma.8 Okada et al. (2019) reported toxicity
profiles of the double-conditioning regimen in a further
cohort.9 Recently, high efficacy of the
double-conditioning regimen for high-risk medulloblastoma was
published.10 In contrast, few studies have
investigated the double-conditioning regimen for high-risk
neuroblastoma.11 This study re-evaluated the safety of
the double-conditioning regimen and assesses its efficacy for high-risk
neuroblastoma in a multi-institutional cohort.