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Leukemia : normal and malignant hemopoiesis 36(7), 1825-1833 (2022). doi:10.1038/s41375-022-01589-y, Published by Springer Nature, London

BACKGROUND: The leukemia cells of approximately 95% of patients with chronic myeloid leukemia and 30%-50% of adult patients with acute lymphoblastic leukemia express the Bcr/Abl oncoprotein, which is the product of a fusion gene created by a chromosomal translocation [(9:22) (q34;q11)]. This oncoprotein expresses a constitutive tyrosine kinase activity that is crucial for its cellular transforming activity. In this study, we evaluated the antineoplastic activity of CGP57148B, which is a competitive inhibitor of the Bcr/Abl tyrosine kinase. METHODS: Nude mice were given an injection of the Bcr/Abl-positive human leukemia cell lines KU812 or MC3. Tumor-bearing mice were treated intraperitoneally or orally with CGP57148B according to three different schedules. In vitro drug wash-out experiments and in vivo molecular pharmacokinetic experiments were performed to optimize the in vivo treatment schedule. RESULTS: Treatment schedules administering CGP57148B once or twice per day produced some inhibition of tumor growth, but no tumor-bearing mouse was cured. A single administration of CGP57148B caused substantial (>50%) but short-lived (2-5 hours) inhibition of Bcr/Abl kinase activity. On the basis of the results from in vitro wash-out experiments, 20-21 hours was defined as the duration of continuous exposure needed to block cell proliferation and to induce apoptosis in these two leukemia cell lines. A treatment regimen assuring the continuous block of the Bcr/Abl phosphorylating activity that was administered over an 11-day period cured 87%-100% of treated mice. CONCLUSION: These data indicate that the continuous block of the oncogenic tyrosine kinase of Bcr/Abl protein is needed to produce important biologic effects in vivo

Tyrosine kinases (TKs) play a significant role in cancerogenesis and cancer cell function. Initial developments in this field go back to the early 80s, but the success story really started with the selective BCR-ABL inhibitor, imatinib. Owing to the cancer-driving role of BCR-ABL in chronic myeloid leukemia (CML), excellent response rates lead to fast FDA approval in both the first and second treatments of CML patients. Since then, numerous TKs were identified. TK inhibitors have been developed accordingly, and technology to test for ideal drug-target interactions has profoundly improved. By now, medical oncologists and hematologists struggle to have a pool of potential TK inhibitors, where the most efficient one could be picked out to treat a specific cancer patient, which might also help overcome the occurring resistance mechanisms against TK inhibitors. Whether disease eradication can be achieved via single or sequential TK inhibitor treatment(s) needs to be tested in the present and in the future.

The tyrosine kinase receptor c-Kit is critically involved in the modulation of nociceptive sensitivity in mice. Ablation of the c-Kit gene results in hyposensitivity to thermal pain, whereas activation of c-Kit produces hypersensitivity to noxious heat, without altering sensitivity to innocuous mechanical stimuli. In this study, we investigated the role of c-Kit signaling in human pain perception. We hypothesized that subjects treated with Imatinib or Nilotinib, potent inhibitors of tyrosine kinases including c-Kit but also Abl1, PDFGFRα, and PDFGFRβ, that are used to treat chronic myeloid leukemia (CML), would experience changes in thermal pain sensitivity. We examined 31 asymptomatic CML patients (14 male and 17 female) receiving Imatinib/Nilotinib treatment and compared them to 39 age- and sex-matched healthy controls (12 male and 27 female). We used cutaneous heat and cold stimulation to test normal and noxious thermal sensitivity, and a grating orientation task to assess tactile acuity. Thermal pain thresholds were significantly increased in the Imatinib/Nilotinib-treated group, whereas innocuous thermal and tactile thresholds were unchanged compared to those in the control group. In conclusion, our findings suggest that the biological effects of c-Kit inhibition are comparable in mice and humans in that c-Kit activity is required to regulate thermal pain sensitivity but does not affect innocuous thermal and mechanical sensation. The effect on experimental heat pain observed in our study is comparable to those of several common analgesics; thus modulation of the c-Kit pathway can be used to specifically modulate noxious heat and cold sensitivity in humans.

Chronic myeloid leukemia developing after transplantation of solid organs and concomitant immunosuppression is a rare but still significant clinical phenomenon. We here describe an additional case of a 62-year-old male patient developing CML after orthotopic heart transplantation and medication with cyclosporine A, mofetil-mycophenolate, and steroids. Initial antileukemic therapy was imatinib at a standard dose and within 15 months of therapy a complete cytogenetic response was noted. In this report we discuss the clinical implications of these rare but biologically important cases.

Titelblatt Gesamthabilitationsschrift, Die chronische myeloische Leukämie ist eine monoklonale Stammzellneoplasie. Der Identifikation einer reziproken chromosomalen Translokation (t(9;22)(q34;q11)), dem sogenannten Philadelphia Chromosom, bei nahezu allen Patienten mit CML, folgte die Entdeckung des Bcr-Abl Fusionstranskriptes bzw. des p210Bcr-Abl Fusionsproteins, einer onkogenen Tyrosinkinase. Umfangreiche zellbiologische und tierexperimentelle Studien bewiesen die kausale Bedeutung der p210Bcr-Abl Tyrosinkinase für die Leukämogenese der CML. Die ausschließliche Expression von p210Bcr-Abl in CML-Zellen führte zur Entwicklung spezifischer, zielgerichteter Therapieansätze, die unter dem Begriff targeted therapy bekannt geworden sind. Der spezifische Tyrosinkinaseinhibitor Imatinib hat in diesem Sinne zu einer drastischen Verbesserung der Therapie geführt. In präklinischen Modellen konnte die Effektivität dieser Substanz in Bezug auf die Hemmung der Proliferationsrate, der Rekonstitution der apoptose und der Tumorgrößenreduktion gezeigt werden. Sich anschließende klinische Studien zeigten eine hochsignifikante klinische Überlegenheit gegenüber der bisherigen Standardtherapie bestehend aus Interferon-alpha. Mittels quantitativer RT-PCR konnte bei Patienten in chronischer Phase eine langanhaltende und signifikante Reduktion von Bcr-Abl Fusiontranskripten gezeigt werden. Bereits vor der Initiierung klinischer Studien wurde mit der Identifizierung möglicher Resistenzmechanismen begonnen. In Zellkulturmodellen konnte die Amplifikation der t(9;22) Translokation und die konsekutive Überexpression von p210Bcr-Abl als ein Resistenzmechanismus identifiziert werden, der in der späteren klinischen Anwendung tatsächlich beobachtet wurde. Das Auftreten von Punktmutationen im Bereich der Imatinib-Bindungsstelle stellt einen weiteren Resistenzmechanismus mit signifikanter klinischer Relevanz dar. Das Auftreten von Rezidiven aufgrund unterschiedlicher Resistenzmechanismen belegt die Notwendigkeit der Therapieoptimierung. Neben der Dosissteigerung, der Kombination mit bisherigen antileukämieschen Substanzen, der Identifizierung von Hochrisikopatienten mit dem Ziel einer allogenen Stammzelltransplantation und der Entwicklung neuer Tyrosinkinaseinhibitoren besteht eine zusätzliche alternative Therapieoptionen in der Sammlung CD34+ Stammzellen bei Patienten in kompletter zytogenetischer Remission, gegebenenfalls gefolgt von einer autologen Stammzelltransplantation. In präliminären Ansätzen konnte hierbei die Durchführbarkeit einer kombinierten Gabe von G-CSF und Imatinib gezeigt werden., Chronic myeloid leukemia is a monoclonal stem cell disorder. The identification of a reciprocal chromosomal translocation ((t(9;22)(q34;q11)), known as the Philadelphia chromosome, in almost all patients with CML was followed by the dicovery of the Bcr-Abl fusiontranscript and the oncogenic p210Bcr-Abl fusionprotein with tyrosine kinase activity. Numerous in-vitro and in-vivo studies proofed the causative significance of the p210Bcr-Abl tyrosine kinase in the leukemogenesis of CML. The exclusive expression of p210Bcr-Abl in CML cells resulted in the development of specific, targeted therapeutic approaches known as targeted therapy . The specific tyrosine kinase inhibitor Imatinib resulted in a dramatic imrovement of therapy in this context. In preclinical models the efficacy of this substance to inhibit proliferation, to reconstitute apoptosis and to reduce tumor growth could be demonstrated. Consecutive clinical trials showed highly significant superiority of this substance over the previous standard therapy consisting in interferon-alpha. In patients with chronic phase CML a long lasting and significant reduction of Bcr-Abl fusiontranscripts could be shown with quantitative rt-PCR. Already before the initiation of clinical trials the identification of potential mechanisms of resistance started. In cell culture systems the amplification of the t(9;22) translocation and the consecutive overexpression of p210Bcr-Abl was observed and confirmed in the clinical setting later on. The occurence of pointmutations within the imatinib-binding region is an additional mechanism of clinical relevance. The emergence of relapses of leukemia underlines the importance of optimising the therapeutic options in CML. In addition to dose escalation, the combination of antileukemic substances and the identification of high risk patients eligable for allogeneic stem cell transplantation and the development of new tyrosine kinase inhibitors the collection of CD34+ stem cells, followed by autologous transplantation represents a therapeutic alternative. In this context preliminary approaches demonstrated the feasability of a combined administration of G-CSF and Imatinib.

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.

Leukemia : normal and malignant hemopoiesis 30(1), 57-64 (2016). doi:10.1038/leu.2015.270, Published by Nature Publ. Group, Basingstoke

Journal of cancer research and clinical oncology 143(8), 1585-1596 (2017). doi:10.1007/s00432-017-2402-x, Published by Springer, Berlin ; Heidelberg ; New York

International audience; This is a pivotal, multicenter, open-label study of moxetumomab pasudotox, a recombinant CD22-targeting immunotoxin, in hairy cell leukemia (HCL), a rare B cell malignancy with high CD22 expression. The study enrolled patients with relapsed/ refractory HCL who had ≥2 prior systemic therapies, including ≥1 purine nucleoside analog. Patients received moxetumomab pasudotox 40 µg/kg intravenously on days 1, 3, and 5 every 28 days for ≤6 cycles. Blinded independent central review determined disease response and minimal residual disease (MRD) status. Among 80 patients (79% males; median age, 60.0 years), durable complete response (CR) rate was 30%, CR rate was 41%, and objective response rate (CR and partial response) was 75%; 64 patients (80%) achieved hematologic remission. Among complete responders, 27 (85%) achieved MRD negativity by immunohistochemistry. The most frequent adverse events (AEs) were peripheral edema (39%), nausea (35%), fatigue (34%), and headache (33%). Treatment-related serious AEs of hemolytic uremic syndrome (7.5%) and capillary leak syndrome (5%) were reversible and generally manageable with supportive care and treatment discontinuation (6 patients; 7.5%). Moxetumomab pasudotox treatment achieved a high rate of independently assessed durable response and MRD eradication in heavily pretreated patients with HCL, with acceptable tolerability.

PURPOSE: The ENEST1st sub-analysis presents data based on Philadelphia chromosome (Ph) status, i.e., Ph+ and Ph-/BCR-ABL1 + chronic myeloid leukemia.METHODS: Patients received nilotinib 300 mg twice daily, up to 24 months.RESULTS: At screening, 983 patients were identified as Ph+ and 30 patients as Ph-/BCR-ABL + based on cytogenetic and RT-PCR assessment; 76 patients had unknown karyotype (excluded from this sub-analysis). In the Ph-/BCR-ABL1 + subgroup, no additional chromosomal aberrations were reported. In the Ph+ subgroup, 952 patients had safety and molecular assessments. In the Ph-/BCR-ABL1 + subgroup, 30 patients had safety assessments and 28 were followed up for molecular assessments. At 18 months, the molecular response (MR) 4 rate [MR4; BCR-ABL1 ≤0.01% on International Scale (IS)] was similar in the Ph-/BCR-ABL1+ (39.3%) and Ph+ subgroups (38.1%). By 24 months, the cumulative rates of major molecular response (BCR-ABL1IS≤0.1%;), MR4, and MR4.5(BCR-ABL1IS≤0.0032%) were 85.7, 60.7, and 50.0%, respectively, in the Ph-/BCR-ABL1 + subgroup, and 80.3, 54.7, and 38.3%, respectively, in the Ph+ subgroup. In both Ph-/BCR-ABL1 + and Ph+ subgroups, rash (20 and 22%), pruritus (16.7 and 16.7%), nasopharyngitis (13.3 and 10.4%), fatigue (10 and 14.2%), headache (10 and 15.8%), and nausea (6.7 vs 11.4%) were frequent non-hematologic adverse events, whereas hypophosphatemia (23.3 and 6.8%), anemia (10 and 6.5%), and thrombocytopenia (3.3 and 10.2%) were the common hematologic/biochemical laboratory events.CONCLUSION: Based on similar molecular response and safety results in both subgroups, we conclude that Ph-/BCR-ABL1 + patients benefit from nilotinib in the same way as Ph+ patients.

PURPOSE: Achievement of deep molecular response with a tyrosine kinase inhibitor in patients with chronic myeloid leukemia (CML) is required to attempt discontinuation of therapy in these patients. The current subanalysis from the Evaluating Nilotinib Efficacy and Safety in Clinical Trials as First-Line Treatment (ENEST1st) study evaluated whether age has an impact on the achievement of deeper molecular responses or safety with frontline nilotinib in patients with CML.METHODS: ENEST1st is an open-label, multicenter, single-arm, prospective study of nilotinib 300 mg twice daily in patients with newly diagnosed CML in chronic phase. The patients were stratified into the following 4 groups based on age: young (18-39 years), middle age (40-59 years), elderly (60-74 years), and old (≥75 years). The primary end point was the rate of molecular response 4 ([MR4] BCR-ABL1 ≤0.01% on the international scale) at 18 months from the initiation of nilotinib.RESULTS: Of the 1091 patients enrolled, 1089 were considered in the analysis, of whom, 23% (n = 243), 45% (n = 494), 27% (n = 300), and 5% (n = 52) were categorized as young, middle age, elderly, and old, respectively. At 18 months, the rates of MR4were 33.9% (95% confidence interval [CI], 27.8-40.0%) in the young, 39.6% (95% CI, 35.3-44.0%) in the middle-aged, 40.5% (95% CI, 34.8-46.1%) in the elderly, and 35.4% (95% CI, 21.9-48.9%) in the old patients. Although the incidence of adverse events was slightly different, no new specific safety signals were observed across the 4 age groups.CONCLUSIONS: This subanalysis of the ENEST1st study showed that age did not have a relevant impact on the deep molecular response rates associated with nilotinib therapy in newly diagnosed patients with CML and eventually on the eligibility of the patients to attempt treatment discontinuation.