Langerhans cell histiocytosis (LCH) is a rare protean disease that usually affects children. Few data are available for management of adult‐onset cases. A complete picture of the efficacy and safety of 2CdA (2‐chlorodeoxyadenosine, cladribine) is lacking. We report a retrospective multicentre study of 23 adult LCH (a‐LCH) patients who received single‐agent 2CdA and a systematic literature review. All had previously received systemic therapy (vinblastine, n  = 19). Response to 2CdA was evaluable in 22 cases. Overall response rate (ORR) was 91%. Complete response (CR) occurred in 11 cases (50%). Nine patients (39%) developed grade 3–4 neutropenia and/or severe infection. A literature review yielded 48 additional cases. A pooled analysis confirmed our findings (ORR: 88%, CR: 49%). CRs were rare with cumulative dose <50 mg/m². Disease progression rates were 20% and 30% at two and five years, respectively. Partial response (PR) to 2CdA was predictive of disease progression. Among eight re‐treated patients, five went into CR, two in PR, and one died. Single‐agent 2CdA is effective in reactivated a‐LCH, including at intermediate doses. Toxicity, significant but acceptable, warrants infectious prophylaxis. Complete responders may enter prolonged remission. Further studies are needed to determine 2CdA sequencing with other agents (vinblastine, cytarabine).

中文翻译：

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2CdA（克拉屈滨）对成年肺外成年朗格汉斯细胞组织细胞增生症的长期疗效和安全性：法国组织细胞增生症组的23例病例分析和系统的文献综述。

朗格汉斯细胞组织细胞增生症（LCH）是一种罕见的蛋白质病，通常会影响儿童。很少有数据可用于治疗成人发病。尚缺乏2CdA（2-氯脱氧腺苷，克拉屈滨）疗效和安全性的完整图片。我们报告了一项对23名接受单药2CdA的成年LCH（a-LCH）患者的回顾性多中心研究，并进行了系统的文献综述。所有人以前都接受过全身治疗（长春碱，n = 19）。22例患者对2CdA的反应可评估。总体响应率（ORR）为91％。11例（50％）发生完全缓解（CR）。9名患者（39％）发生3-4级中性粒细胞减少和/或严重感染。文献综述又产生了48个案例。汇总分析证实了我们的发现（ORR：88％，CR：49％）。累积剂量<50 mg / m ^2的CR很少见。两年和五年的疾病进展率分别为20％和30％。对2CdA的部分反应（PR）可预测疾病进展。在八名再次接受治疗的患者中，有五名进入CR，两名在PR中死亡，另一名死亡。单剂2CdA可有效地激活a-LCH，包括中等剂量。毒性很大，但是可以接受，可以预防感染。完全反应者可能会进入长期缓解期。还需要进一步的研究来确定与其他药物（长春碱，阿糖胞苷）的2CdA测序。