In chronic myeloid leukaemia (CML), dendritic cells (DC) and leukaemic cells share a common progeny, leading to constitutive expression of putative tumour antigens, such as bcr/abl, in DC. In this phase-I/II study, autologous DC were used as a vaccine in patients with chronic phase bcr/abl+ CML, who had not achieved an adequate cytogenetic response after treatment with alpha-interferon or imatinib. Ten patients were enrolled, DC were generated from peripheral blood monocytes and vaccination consisted of four subcutaneous injections of increasing numbers of DC (1-50 x 10(6) cells per injection) on days 1, 2, 8 and 21. Vaccination was feasible and safe. Improvement of the cytogenetic/molecular response, as detected by fluorescence in situ hybridization of peripheral blood mononuclear cells (PBMC), was possibly related to vaccination in four of 10 patients. In three of these patients, T cells recognizing leukaemia-associated antigens became detectable. The proliferative capacity of PBMC in response to autologous DC increased after vaccination in all evaluable patients. We conclude that vaccination with autologous, non-irradiated 'leukaemic' DC is feasible, safe and induces anti-leukaemic T-cell responses in some CML patients. DC vaccination might be useful in CML as postremission therapy, i.e. after treatment with tyrosine kinase inhibitors.

Idiopathic hypereosinophilic syndrome (HES) is a rare myeloproliferative disorder characterized by sustained overproduction of eosinophils and organ involvement that can lead to chronic eosinophilic leukemia. HES is a clonal disorder characterized in some patients by constitutive activation of FIP1L1-PDGFRA. There is currently no approved therapy for HES. Nilotinib is a novel aminopyrimidine which potently inhibits Bcr-Abl, as well as the PDGF-R and c-Kit kinases. This Phase II study was designed to evaluate the safety and efficacy of nilotinib administered at an oral dose of 400 mg twice daily to patients with specific HES disease related criteria and with a clinical indication for treatment. Preliminary data are available for 11 patients. The median age is 63 (range 25–77) years. There were 10 males and 1 female. Extramedullary involvement was present in 6 (55%) patients at baseline. Treatment is ongoing for 4 (36%) patients and 7 (64%) have discontinued; 2 (18%) for adverse events; 3 (27%) for disease progression, and 1 (9%) for an administrative reason. There was one patient death due to neutropenic sepsis and endocarditis. Overall, 5 (45%) patients had investigator documented stable disease, and 1 (9%) patient a 51 year old male had a CR. Grade 3 or 4 adverse events included one patient each with rash, decreased hemoglobin, myalgia, arthralgia, pruritis, and diabetes mellitus. In summary, these data suggest that nilotinib has clinical activity and an acceptable safety and tolerability profile in patients with HES.

In order to detect T cells against several chronic myeloid leukaemia (CML)-associated antigens we used: (i) a novel T-cell assay [cytometric bead array (CBA)]; (ii) gamma-interferon enzyme-linked immunoSPOT (gamma-IFN-ELISpot); and (iii) tetramer staining in peripheral blood from CML patients. Peptide-specific cytokine release was detected by CBA in some patients, whereas standard gamma-IFN-ELISpot and tetramer staining were negative in the vast majority of cases. In CBA, peptide-specific cytokine release was predominantly tumour necrosis factor-alpha, raising questions about the responding cells and their functional status. CBA appears to be a new useful tool for the detection of leukaemia-reactive T cells.

T cells recognising leukemia-associated antigens are present in the T cell repertoire of a subgroup of patients with AML and CML. Difficulties in the detection of such leukemia-reactive T cells in peripheral blood samples of patients are mainly attributed to the low frequency of leukemia-specific T cells.

Background: In normal hemopoesis WT1 expression is restricted to early progenitors and is rapidly down-regulated in maturing blood cells. WT1 transcript quantification therefore may be an adjunct diagnostic method in CML patients (pts) that remain Bcr-Abl positive under treatment. Especially, in advanced CML pts WT1 transcript kinetics may precede a change in Bcr-Abl kinetics and may therefore be helpful to indicate early response to treatment. Nilotinib is a potent, highly selective, second generation Bcr-Abl inhibitor which in vitro is 30-fold more potent than imatinib and is currently studied in imatinib resistant or intolerant pts. Aim: The aim of this study was to compare kinetics of Bcr-Abl and WT1 transcripts in 33 CML pts with late chronic phase (CP) or advanced disease under treatment with nilotinib. Methods: All pts were treated as part of an ongoing phaseI/II clinical trial with nilotinib at a standard dose of 400 mg BID. 20 pts were in chronic phase (CP), 4 in accelerated phase (AP) and 9 in blast crisis (BC). Among the CP pts 4/20 were enrolled because of toxicity to prior imatinib treatment. WT1 and Bcr-Abl kinetics were expressed in relation to Abl expression. Data points were taken at baseline and every 4 weeks thereafter. Quantitative PCR was carried out by Taqman-analysis. Results: The median duration of nilotinib treatment was 8 months in CP pts, 4 in AP pts and 5.5 in BC pts. The follow up of all pts ranged between 3 and 13 months. All pts received imatinib prior to nilotinib and were Bcr-Abl positive at study entry. In CP samples WT1/Abl ratios (median:1.24x10−3) were 38 fold lower than Bcr-Abl/Abl (median:4.67x10−2) ratios at baseline (p≤0.014, t-test). However, in AP and BC pts no relevant difference of WT1/Abl and Bcr-Abl/Abl baseline levels were detectable. In BC patients a more rapid decline of WT1/Abl ratios compared to Bcr-Abl/Abl ratios was observed within the first four months of nilotinib therapy. In addition, in BC pts elevation of WT1 levels preceded hematologic relapses and was detectable earlier than elevation of Bcr-Abl/Abl ratios. Conclusions:In contrast to AP and BC pts in CP pts WT1/Abl ratios were significantly lower than Bcr-Abl/Abl ratios confirming the restriction of WT1 expression to early progenitors.In BC pts under nilotinib therapy WT1/Abl ratios may be an early marker of response as compared to Bcr-Abl/Abl ratios.A stable correlation of WT1/Abl and Bcr-Abl/Abl ratios was observed in AP pts under treatment.

T cells recognizing truly leukemia-specific antigens like bcr/abl or other leukemia-associated antigens such as proteinase-3 and WT-1 are present in the T cell repertoire of leukemia patients and several studies have suggested that anti-leukemic T cells might be of clinical relevance. Detection of these leukemia-reactive T cells in CML patients is generally hampered by their low frequency making in vitro prestimulation necessary in most cases. Furthermore, shaping of the T cell repertoire by deletion of high affinity leukemia-reactive T cells and functional unresponsiveness are likely to have additional influence on T cell detection in structural or functional assays.

Despite the remarkable clinical response rates to imatinib in the treatment of bcr-abl leukemic patients, pharmacokinetic data on this relatively novel substance are needed to improve our understanding of the emergence of resistance, the interindividual variations of clinical response and the clinical and biologic relevance of its main metabolite N-desmethyl-imatinib. We present here pharmacokinetic data obtained with a newly designed HPLC approach in 97 patients with chronic myeloid leukemia or acute lymphatic leukemia (ALL) under treatment with imatinib that allowed us to calculate the AUC (39.5 μg·h/ml for an oral dose of 400 mg daily), the t1/2 (18.2 h) and the peak concentration (1.92 μ/ml for an oral dose of 400 mg daily) of imatinib in plasma. In a subgroup of patients, the same parameters were analyzed for N-desmethyl-imatinib. We also provide data on the imatinib concentration in the cerebrospinal fluid (CSF) of ALL patients and demonstrate that oral administration of imatinib resulted only in a marginal flux across the blood-brain barrier. Finally, in an in vitro setting, we determined cellular concentrations of imatinib in HL-60 cells and showed an over-proportional uptake both in RPMI medium and in human plasma. Using an arithmetical approach combining all parameters obtained in imatinib-treated patients, we finally provide a conclusive approximation of basic pharmacokinetic data for both imatinib and its main metabolite N-desmethyl-imatinib.

Summary Therapy with imatinib mesylate is limited by cellular resistance in chronic myeloid leukaemia (CML). Further, the limited availability of matching stem cell donors or an unfavourable risk profile for allogeneic stem cell transplantation (SCT) reduces the number of therapeutic options in a number of patients. To assess the possibility of stem cell mobilization (SCM) during imatinib therapy we performed granulocyte colony‐stimulating factor (filgrastim)‐induced SCM and subsequent aphaeresis in 15 chronic phase and three accelerated phase CML patients. Aphaeresis was successful in 13 patients (72%) (≥2·0 × 10 6 CD34 + cells/kg body weight) and five (28%) harvests could be obtained, which were negative for BCR/ABL mRNA as assessed by nested‐reverse transcription polymerase chain reaction (RT‐PCR). All harvests, except one, were negative after first round RT‐PCR, implicating a low level of CML cell contamination. There was no significant change in peripheral BCR/ABL transcript load after SCM as assessed by quantitative real‐time RT‐PCR. Fifteen patients remained stable in complete cytogenetic remission (CCR) during a median observation period of 9·3 months. One patient achieved a molecular remission shortly after SCM. Another patient who exhibited rising BCR/ABL mRNA levels before SCM achieved CCR after autologous SCT with the generated harvest. One patient with a Philadelphia chromosome‐negative, BCR/ABL ‐positive CML showed a cytogenetic relapse 6 months after SCM. We conclude that filgrastim‐induced CD34 + cell aphaeresis under simultaneous imatinib medication is safe and feasible in CML patients. Additionally, we found evidence that this procedure could generate stem cell harvests that exhibit non‐detectable levels of BCR/ABL mRNA.

T cells recognizing truly leukemia-specific antigens like bcr/abl or other leukemia-associated antigens such as proteinase3 and WT1 have been demonstrated by several groups. In chronic myeloid leukemia (CML), DC and leukemic cells share a common progeny, leading to constitutive expression of putative tumor antigens such as bcr/abl in DC.

The selective tyrosine kinase inhibitor imatinib eradicates bcr-abl+ cells in chronic myeloid leukemia patients (pts). Although a previous clinical trial showed superiority of an imatinib therapy over an interferon-α containing regimen, a significant number of pts eventually relapse with leukemia because of either point mutations within the imatinib-binding site, amplification of the Philadelphia chromosome or other mechanisms, e.g. clonal evolution. AMN107 (Novartis Pharma AG) is a new anilino-pyrimidine derivative (MW: 529.5) structurally related to imatinib.

Previous clinical trials with the tyrosine kinase inhibitor imatinib in chronic‐phase Philadelphia chromosome‐positive chronic myelogenous leukemia (CML) resulted in 95% of hematologic and 60% major cytogenetic remissions in patients who failed a previous interferon‐α‐containing regimen. In an identical clinical trial setting with 39 chronic‐phase CML patients we achieved comparable cytogenetic response rates after a median follow up of 30.1 weeks, with an almost identical toxicity profile. In order to identify predictive markers for the therapeutical use of imatinib, we monitored apart from standard hematology parameters bcr/abl fusion transcripts by quantitative real‐time fluorescence RT‐PCR. As previous investigations demonstrated that the plasma protein α‐1 acid glycoprotein might inactivate circulating levels of free imatinib by protein binding with high affinity, we assessed plasma α‐1 acid glycoprotein concentrations in our study cohort as well. Median bcr/abl fusion transcripts declined gradually over the entire treatment period and became significantly lowered at month 3 after initiation of imatinib therapy. Further, we observed elevated pretreatment levels of α‐1 acid glycoprotein in patients who relapsed with leukemia, whereas initial bcr/abl mRNA copy numbers were not of predictive value. In addition, we provide data showing molecular response to this therapy in the vast majority of patients. Finally, our results support the hypothesis, that initially elevated plasma levels of α‐1 acid glycoprotein might serve as a predictive marker for the clinical outcome of treatment with imatinib. Am. J. Hematol. 73:249–255, 2003. © 2003 Wiley‐Liss, Inc.

Abstract. Imatinib (glivec®, formerly known as STI571) effectively blocks the ATP‐binding site of the bcr/abl fusion protein thereby inactivating selectively the tyrosine kinase activity of bcr/abl. Therefore, it is a promising drug in Philadelphia chromosome positive chronic myeloid leukemia showing high hematologic and cytogenetic response rates combined with a mild toxicity profile. Here we report two cases of squamous cell carcinoma of the skin, which appeared in the photoexposed areas in two elderly patients treated for advanced chronic myeloid leukemia with imatinib. The role of chemotherapy, chronic sun exposure and of possible additional risk factors such as human papillomavirus infection is discussed.

Imatinib mesylate blocks bcr/abl kinase activity effectively, and thus is a promising drug in Philadelphia chromosome positive leukemias. While under imatinib treatment high hematological and cytogenetic response rates could be observed, usually only mild non-hematological side-effects like skin rash, edema, and muscular cramps occur. Here we report two severe cases of acute generalized exanthematous pustulosis due to imatinib. In both patients the generalized pustular eruptions could be observed 12 wk after initiation of imatinib treatment. Numerous microbiological investigations excluded an infectious etiology, and histopathology of cutaneous lesions was consistent with acute generalized exanthematous pustulosis. Accordingly, withdrawal of imatinib led to a restitutio at integrum of the integument. Our report confirms another single observation of acute generalized exanthematous pustulosis in chronic myeloid leukemia under imatinib therapy, and confirms that this is a rare but proven adverse effect of imatinib.