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对于一些慢性骨髓性白血病(chronic myeloid leukemia，CML)病患，在达到完整的分子生物学上缓解之后，或许可以停用imatinib mesylate(Gleevec)。于美国血液学会(ASH)第50届年会与展览会中发表的研究，确认了一篇先驱研究的结果，指出在停用imatinib之后可以持续有缓解效果，特别是事先已经使用干扰素治疗的病患。
主要作者、法国Victor Segalen CHU de Bordeaux大学H?matopo??se leuc?mique的Fran?ois-Xavier Mahon医师报告指出，停用imatinib是可行的，且不会主动导致复发。
Mahon医师表示，Imatinib大幅改善CML的存活，但是病患必须继续治疗一段未知的期间。
Imatinib是一种BCR-ABL酪胺酸激酶抑制物，可以在85%以上的CML病患诱导完整的细胞生成反应；不过，研究者指出，完整细胞生成反应的病患倾向在停用imatinib时复发，不到10%的病患达到分子生物学上的缓解，其定义为以即时定量聚合酶连锁反应侦测不出残余疾病。
之前，Mahon医师等人主导一个先驱研究，探索完整分子生物学上缓解之CML病患停用imatinib的可能性，在总共15名病患中，7人在6个月内复发，但他们可以在再度使用imatinib之后再度达到完整分子生物学上缓解，其他8个病患在停用imatinib之后持续缓解(平均追踪期为37个月)。
Mahon医师指出，那些未复发的病患全都事先接受了干扰素治疗。
目前这次试验包括了法国22家中心的69名病患，其中60人已经追踪超过1个月，平均年纪为62岁(范围为32–81岁)，有31人曾经接受过干扰素治疗，29人重新治疗；为了符合纳入标准，病患必须接受imatinib治疗且曾达到完整分子生物学反应，至少2年未侦测出BCR-ABL基因转录体。
目前，27名病患于停用imatinib之后复发，大部份的复发发生在停用后的最初6个月内，其中，13名病患曾经接受过干扰素，14名只接受过imatinib。
Mahon医师表示，在9个月时，46%的病患仍然属于缓解，其中53%的病患事先接受了干扰素治疗， 39%为重新治疗的病患。
Mahon医师也强调，全部的复发病患于再度使用imatinib之后仍有感受性，有些复发病患相当迅速地再度达到缓解，但有一些则比较缓慢。Mahon医师表示，虽然本研究的追踪期短，但先驱研究中的病患已经追踪了许多年，两试验的结果都确认了在停用imatinib之后持续有完整的分子反应，特别是那些接受过干扰素治疗的病患。
但是，在那些未事先接受干扰素治疗的病患中，超过半数复发，有20%在追踪6个月以上时仍无复发；Mahon医师结论表示，持续完整分子反应的病患可以停用imatinib治疗，即使是那些只用过imatinib的病患。
美国血液学会(ASH)第50届年会与展览会：摘要187。发表于2008年12月8日。
ASH 2008: Imatinib Can Be Discontinued in Some Patients With CML
By Roxanne Nelson
Medscape Medical News
For some patients with chronic myeloid leukemia (CML), it might be possible to discontinue imatinib mesylate (Gleevec) after they have achieved a complete molecular remission. Research presented here at the American Society of Hematology (ASH) 50th Annual Meeting and Exposition confirmed the results of a pilot study that demonstrated that remission can be sustained after imatinib is discontinued, particularly in patients who have been pretreated with interferon.
The discontinuation of imatinib is feasible and does not automatically lead to relapse, reported lead author, Francois-Xavier Mahon, MD, from Hematopoiese leucemique, Universite Victor Segalen CHU de Bordeaux, in France.
"Imatinib has greatly improved survival in CML," said Dr. Mahon, "but patients must continue on the treatment for an unknown period of time."
Imatinib, a BCR-ABL tyrosine kinase inhibitor, is able to induce a complete cytogenetic response in more than 85% of patients with CML. However, the researchers note that patients with a complete cytogenic response tend to relapse when imatinib is discontinued, and less than 10% of patients achieve a molecular remission, defined by an undetectable residual disease using real-time quantitative–polymerase chain reaction.
Previously, Dr. Mahon and colleagues conducted a pilot study and explored the feasibility of discontinuing imatinib in CML patients who had experienced a complete molecular response. Of the 15 patients included in the cohort, 7 relapsed within 6 months, but they were able to reattain a complete molecular response after imatinib was restarted. The other 8 patients remain in remission after the discontinuation of imatinib (median follow-up is 37 months).
The patients who did not relapse were all pretreated with interferon, Dr. Mahon pointed out.
The current trial looked at 69 patients from 22 centers in France and, of this group, 60 patients had follow-up for more than 1 month. They had a median age of 62 years (range, 32–81 years). Thirty one had been previously treated with interferon, and 29 were de novo. To meet the criteria for inclusion, the patients had to be receiving imatinib treatment and to have had a complete molecular response and undetectable BCR-ABL transcript for at least 2 years.
Currently, 27 patients have relapsed since the discontinuation of their imatinib, and most of the relapses were observed during the first 6 months of discontinuation. Of this group, 13 patients had received interferon and 14 had only received imatinib.
"At 9 months, 46% of patients are still in remission," said Dr. Mahon. "Fifty-three percent were pretreated with interferon and 39% are de novo patients."
Dr. Mahon also emphasized that all of the patients who relapsed were sensitive to imatinib after it was restarted. Some of the relapsed patients went back into remission very quickly, but for others, it is a slower process.
Although the follow-up in this study is short, patients in the pilot study have now been followed for several years. The results from both of these trials confirm that complete molecular response can be sustained after imatinib is discontinued. This is particularly true for patients who have been pretreated with interferon, said Dr. Mahon.
But among the patients who were not pretreated with interferon, over half have not relapsed, and 20% have reached a follow-up of 6 months or more without relapse. Dr. Mahon concluded that it is possible to stop imatinib treatment in patients who have a sustained complete molecular response, even in those who received single-agent treatment with imatinib.
American Society of Hematology (ASH) 50th Annual Meeting and Exposition: Abstract 187. Presented December 8, 2008.