Optic pathway/hypothalamic gliomaに対するビンブラスチン治療—2症例報告

Weekly Vinblastine in Pediatric Optic Pathway/Hypothalamic Glioma:2 Cases Report

Ⅰ．はじめに

　Optic pathway glioma（OPG），そしてOPGにhypothalamic gliomaを併せたoptic pathway/hypothalamic glioma（OPHG）などの，完全切除が不能な部位に発生した小児低悪性度神経膠腫の治療・管理における化学療法の役割は，過去20年間で劇的に変化した¹²⁾．当初，化学療法は手術や放射線療法後の再発に対する救済療法としての選択肢であったが，放射線療法は晩期障害のリスクが高く，一方で，有効な化学療法レジメンが開発された結果，現在では，放射線学的または症候性に進行する切除不能なOPHGを含む小児低悪性度神経膠腫の第一選択治療は，化学療法と考えられている¹²⁾．

　ビンブラスチン単剤を毎週注射投与する治療法（weekly vinblastine［以下，ビンブラスチンの毎週投与］）は，OPHGを含む小児低悪性度神経膠腫における有効な治療法として海外で報告された^3,9,12)．最初は，カルボプラチンのアレルギーにて治療継続が困難になった患者への治療法として報告され⁹⁾，続いて，再発・進行性の低悪性度神経膠腫に対するphase Ⅱ studyで有効性が報告された³⁾．さらに，低悪性度神経膠腫に対するファーストラインの化学療法としての有効性も示されたが¹²⁾，本邦での治療報告論文は，われわれが渉猟し得た限りでは認められない．本稿では保険適用外薬として，1例ごとに院内institutional review board（IRB）で審査を受けて承認後に使用した，OPHGに対するビンブラスチンの毎週投与の治療経験を報告する．

　It is reported that vinblastine monotherapy has promising activity in patients with pediatric optic pathway/hypothalamic glioma（OPHG）who experienced treatment failure after initial treatment with standard chemotherapy. However, there have been no reports on vinblastine monotherapy against OPHG in Japan. Since vinblastine is an unauthorized drug under the Ministry of Health and Welfare, we used it after completing an in-hospital institutional review board application for each case. In the first case, a 6-year-old boy with recurrent OPHG with hydrocephalus was referred to our hospital. Weekly vinblastine was started at a dose of 6mg/m² and was then reduced to 5mg/m² and 4mg/m² sequentially due to hematotoxicity. After 11 cycles of vinblastine, improvement in hydrocephalus was observed. After 22 cycles of vinblastine, the best response was observed, and we continued treatment up to 35 cycles. Progression of the disease was observed after 47 cycles and then we changed treatment to another regimen after 48 cycles of vinblastine. In the second case, a 6-year-old boy with chemotherapy-naïve recurrent OPHG underwent chemotherapy with vincristine and carboplatin. After 9 treatment cycles with carboplatin, hypersensitivity was observed. Subsequently, he was treated using weekly vinblastine as per the same protocol as that in our first case. A moderate response was observed after 18 cycles of vinblastine. After 48 cycles of vinblastine, the best response was observed, and we completed treatment. In both cases, severe adverse events were not observed and the treatment was well-tolerated. Vinblastine administered once per week is well-tolerated and maintains quality of life in children with OPHG.