Morabito F, Stelitano C, Callea I, Filangeri M, Oliva B, Sculli G, Callea V, Nobile F, Brugiatelli M
Dipartimento di Emato-Oncologia, Azienda Ospedaliera Bianchi-Melacrino-Morelli, Reggio Calabra, Italy.
Haematologica. 1996 May-Jun;81(3):224-31.
Chlorambucil (CLB), 2-chlorodeoxyadenosine (2-CDA) and fludarabine (FAMP) are among the most widely used drugs in chronic lymphocytic leukemia (CLL). Therefore we evaluated in vitro sensitivity to these drugs and cross-resistance of purine analogs. In addition, we correlated the in vitro data with the main clinico-hematological variables and surface markers.
Eighty CLL samples obtained from 63 untreated and 17 treated CLL patients were tested in vitro with the MTT assay. Lethal dose (LD)50 values were calculated to determine sensitivity to CLB, 2-CDA and FAMP.
Samples were clustered either for a one-log increase of LD50 values or for LD50 threshold values of 3 microM for FAMP, 0.3 microM for 2-CDA and 7 microM for CLB, which correspond to the therapeutically achievable plasmatic levels of these drugs. A higher number of samples sensitive to 2-CDA were identified by the first approach; with the second method the relative order of sensitivity was FAMP > 2-CDA > CLB. Concerning 2-CDA and FAMP cross-resistance, out of 61 samples resistant to 2-CDA, 29.5% were sensitive to FAMP. Conversely, 13.9% out of 43 samples resistant to FAMP were sensitive to 2-CDA. No correlation was found between the main clinico-hematological features and the LD50 values of each drug either considering the whole series or only the untreated cases. In vitro drug sensitivity was also evaluated during the steady-state of the disease and at disease progression in six untreated cases. We observed a mean increase in the LD50 values of about 13, 38 and 22 times for CLB, FAMP and 2-CDA, respectively. Among the treated cases, the LD50 values of both purine analogs and CLB correlated with bone marrow histology. CLL cells expressing CD14, CD11c, CD11b, and FMC7 were more resistant in vitro to purine analogs but not to CLB.
This study suggests that i) the purine analogs exert a greater cytotoxic effect on CLL cells; ii) 2-CDA and FAMP are not cross-resistant in vitro in a percentage of CLL samples, iii) a possible change in LD50 values may be related to modification of the disease status, and iv) the expression of certain surface markers, which are CLL-unrestricted, identifies samples with higher in vitro resistance to purine analogs.
苯丁酸氮芥（CLB）、2-氯脱氧腺苷（2-CDA）和氟达拉滨（FAMP）是慢性淋巴细胞白血病（CLL）中最常用的药物。因此，我们评估了这些药物的体外敏感性以及嘌呤类似物的交叉耐药性。此外，我们将体外数据与主要临床血液学变量和表面标志物进行了关联。
从63例未经治疗和17例已治疗的CLL患者中获取80份CLL样本，采用MTT法进行体外检测。计算半数致死剂量（LD）50值以确定对CLB、2-CDA和FAMP的敏感性。
样本根据LD50值增加一个对数或根据FAMP的LD50阈值3 microM、2-CDA的0.3 microM和CLB的7 microM进行聚类，这些阈值对应于这些药物在治疗上可达到的血浆水平。第一种方法鉴定出对2-CDA敏感的样本数量更多；第二种方法的敏感性相对顺序为FAMP>2-CDA>CLB。关于2-CDA和FAMP的交叉耐药性，在61份对2-CDA耐药的样本中，29.5%对FAMP敏感。相反，在43份对FAMP耐药的样本中，13.9%对2-CDA敏感。无论是考虑整个系列还是仅考虑未经治疗的病例，主要临床血液学特征与每种药物的LD50值之间均未发现相关性。在6例未经治疗的病例中，还在疾病稳定期和疾病进展期评估了体外药物敏感性。我们观察到CLB、FAMP和2-CDA的LD50值分别平均增加了约13、38和22倍。在已治疗的病例中，嘌呤类似物和CLB的LD50值与骨髓组织学相关。表达CD14、CD11c、CD11b和FMC7的CLL细胞在体外对嘌呤类似物更耐药，但对CLB不耐药。
本研究表明，i）嘌呤类似物对CLL细胞具有更大的细胞毒性作用；ii）在一定比例的CLL样本中，2-CDA和FAMP在体外不存在交叉耐药性；iii）LD50值的可能变化可能与疾病状态的改变有关；iv）某些表面标志物的表达（这些标志物并非CLL所特有）可识别出体外对嘌呤类似物耐药性较高的样本。
