Key Points DPPIV (CD26) is a new specific marker of CML LSC that aids CML diagnostics and the measurement, characterization, and purification of LSC. DPPIV on CML LSC degrades SDF-1 and thereby promotes the niche-escape of LSC, which may contribute to extramedullary myeloproliferation in CML.

The second generation BCR/ABL kinase inhibitor nilotinib is increasingly used for the treatment of imatinib‐resistant chronic myeloid leukemia (CML). So far, nilotinib is considered a well‐tolerated drug with little if any side effects, although an increase in the fasting glucose level has been reported. We examined a series of 24 consecutive CML patients treated with nilotinib in our center for the development of non‐hematologic adverse events. Three of these 24 CML patients developed a rapidly progressive peripheral arterial occlusive disease (PAOD) during treatment with nilotinib. In all three cases, PAOD required repeated angioplasty and/or multiple surgeries within a few months. No PAOD was known before nilotinib‐therapy in these patients, although all three had received imatinib. In two patients, pre‐existing risk factors predisposing for PAOD were known, and one of them had developed diabetes mellitus during nilotinib. In the other 21 patients treated with nilotinib in our center, one less severe PAOD, one myocardial infarction, one spinal infarction, one subdural hematoma, and one sudden death of unknown etiology were recorded. In summary, treatment with nilotinib may be associated with an increased risk of vascular adverse events, including PAOD development. In a subgroup of patients, these events are severe or even life‐threatening. Although the exact mechanisms remain unknown, we recommend screening for pre‐existing PAOD and for vascular risk factors such as diabetes mellitus in all patients before starting nilotinib and in the follow up during nilotinib‐therapy. Am. J. Hematol. 2011. © 2011 Wiley‐Liss, Inc.

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