Tomohiro Morio, Tsubasa Okano, Yujin Sekinaka, Eri Endo, Katsuyuki Hanabusa, Ikuya Tsuge, Shiann Tarng Jou, Masataka Ishimura, Hsin-Hui Yu, Yoshihiro Maruo, Tomiko Kimoto, Tomoaki Kunitsu, Hiroshi Yagasaki, Masami Inoue, Kenichi Yoshida, Yuki Tsujita, Taizo Wada, Kohsuke Imai, Kyoko Suzuki, Seiji Kojima, Sven Kracker, Tetsuzo Tauchi, Yuko Hashimoto, Takehiro Takashima, Yuzaburo Inoue, Toru Uchiyama, Hidetoshi Takada, Kenichi Honma, Motohiro Kato, Masakazu Nagahori, Takashi Kaneko, Yoshiaki Shikama, Naohiko Moriguchi, Tomoko Waragai, Daiei Kojima, Haruka Hiroki, Tamaki Kato, Kanako Mitsui-Sekinaka, Keisuke Tanaka, Anne Durandy, Yuki Bando, Hideki Muramatsu, Kazuhiro Tasaki, Seishi Ogawa, Hirokazu Kanegane, Fuminori Iwasaki, Shigeaki Nonoyama, Tzu Wen Yeh, Chikako Kamae, Toshihiko Shirakawa, Osamu Suzuki, Tomoyo Matsubara, Hideki Sano, Yuki Yuza, Osamu Ohara, and Noriko Mitsuiki
Background Activated phosphatidylinositol-3-OH kinase δ syndrome type 1 (APDS1) is a recently described primary immunodeficiency syndrome characterized by recurrent respiratory tract infections, lymphoid hyperplasia, and Herpesviridae infections caused by germline gain-of-function mutations of PIK3CD. Hematopoietic stem cell transplantation (HSCT) can be considered to ameliorate progressive immunodeficiency and associated malignancy, but appropriate indications, methods, and outcomes of HSCT for APDS1 remain undefined. Objective Our objective was to analyze the clinical manifestations, laboratory findings, prognosis, and treatment of APDS1 and explore appropriate indications and methods of HSCT. Methods We reviewed retrospectively the medical records of cohorts undergoing HSCT at collaborating facilities. Results Thirty-year overall survival was 86.1%, but event-free survival was 39.6%. Life-threatening events, such as severe infections or lymphoproliferation, were frequent in childhood and adolescence and were common indications for HSCT. Nine patients underwent HSCT with fludarabine-based reduced-intensity conditioning. Seven patients survived after frequent adverse complications and engraftment failure. Most symptoms improved after HSCT. Conclusion Patients with APDS1 showed variable clinical manifestations. Life-threatening progressive combined immunodeficiency and massive lymphoproliferation were common indications for HSCT. Fludarabine-based reduced-intensity conditioning–HSCT ameliorated clinical symptoms, but transplantation-related complications were frequent, including graft failure.